Chiller Plant Control

SSAAFFEETTYY WWAARRNNIINNGGOnly qualified personnel should install and service the equipment. The installation, starting up, and servicing of heating, ventilating, and air-conditioningequipment can be hazardous and requires specific knowledge and training. Improperly installed, adjusted or altered equipment by an unqualified personcould result in death or serious injury. When working on the equipment, observe all precautions in the literature and on the tags, stickers, and labels thatare attached to the equipment.

August 2021 BBAASS--AAPPGG003377DD--EENN

Application Guide

Chiller Plant Controlfor the Tracer® SC+ System Controller

©2021 Trane BAS-APG037D-EN

IntroductionRead this manual thoroughly before operating or servicing this unit.

Warnings, Cautions, and NoticesSafety advisories appear throughout this manual as required. Your personal safety and theproper operation of this machine depend upon the strict observance of these precautions.

The three types of advisories are defined as follows:

WARNINGIndicates a potentially hazardous situation which, if not avoided, could result indeath or serious injury.

CAUTIONIndicates a potentially hazardous situation which, if not avoided, could result inminor or moderate injury. It could also be used to alert against unsafe practices.

NOTICEIndicates a situation that could result in equipment or property-damage onlyaccidents.

Important Environmental ConcernsScientific research has shown that certain man-made chemicals can affect the earth’s naturallyoccurring stratospheric ozone layer when released to the atmosphere. In particular, several of theidentified chemicals that may affect the ozone layer are refrigerants that contain Chlorine,Fluorine and Carbon (CFCs) and those containing Hydrogen, Chlorine, Fluorine and Carbon(HCFCs). Not all refrigerants containing these compounds have the same potential impact to theenvironment. Trane advocates the responsible handling of all refrigerants-including industryreplacements for CFCs and HCFCs such as saturated or unsaturated HFCs and HCFCs.

Important Responsible Refrigerant PracticesTrane believes that responsible refrigerant practices are important to the environment, ourcustomers, and the air conditioning industry. All technicians who handle refrigerants must becertified according to local rules. For the USA, the Federal Clean Air Act (Section 608) sets forththe requirements for handling, reclaiming, recovering and recycling of certain refrigerants andthe equipment that is used in these service procedures. In addition, some states or municipalitiesmay have additional requirements that must also be adhered to for responsible management ofrefrigerants. Know the applicable laws and follow them.

WWAARRNNIINNGGPPrrooppeerr FFiieelldd WWiirriinngg aanndd GGrroouunnddiinngg RReeqquuiirreedd!!FFaaiilluurree ttoo ffoollllooww ccooddee ccoouulldd rreessuulltt iinn ddeeaatthh oorr sseerriioouuss iinnjjuurryy..AAllll ffiieelldd wwiirriinngg MMUUSSTT bbee ppeerrffoorrmmeedd bbyy qquuaalliiffiieedd ppeerrssoonnnneell.. IImmpprrooppeerrllyy iinnssttaalllleedd aannddggrroouunnddeedd ffiieelldd wwiirriinngg ppoosseess FFIIRREE aanndd EELLEECCTTRROOCCUUTTIIOONN hhaazzaarrddss.. TToo aavvooiidd tthheessee hhaazzaarrddss,,yyoouu MMUUSSTT ffoollllooww rreeqquuiirreemmeennttss ffoorr ffiieelldd wwiirriinngg iinnssttaallllaattiioonn aanndd ggrroouunnddiinngg aass ddeessccrriibbeedd iinnNNEECC aanndd yyoouurr llooccaall//ssttaattee//nnaattiioonnaall eelleeccttrriiccaall ccooddeess..

BAS-APG037D-EN 3

WWAARRNNIINNGGPPeerrssoonnaall PPrrootteeccttiivvee EEqquuiippmmeenntt ((PPPPEE)) RReeqquuiirreedd!!FFaaiilluurree ttoo wweeaarr pprrooppeerr PPPPEE ffoorr tthhee jjoobb bbeeiinngg uunnddeerrttaakkeenn ccoouulldd rreessuulltt iinn ddeeaatthh oorr sseerriioouussiinnjjuurryy..TTeecchhnniicciiaannss,, iinn oorrddeerr ttoo pprrootteecctt tthheemmsseellvveess ffrroomm ppootteennttiiaall eelleeccttrriiccaall,, mmeecchhaanniiccaall,, aannddcchheemmiiccaall hhaazzaarrddss,, MMUUSSTT ffoollllooww pprreeccaauuttiioonnss iinn tthhiiss mmaannuuaall aanndd oonn tthhee ttaaggss,, ssttiicckkeerrss,, aannddllaabbeellss,, aass wweellll aass tthhee iinnssttrruuccttiioonnss bbeellooww::

•• BBeeffoorree iinnssttaalllliinngg//sseerrvviicciinngg tthhiiss uunniitt,, tteecchhnniicciiaannss MMUUSSTT ppuutt oonn aallll PPPPEE rreeqquuiirreedd ffoorrtthhee wwoorrkk bbeeiinngg uunnddeerrttaakkeenn ((EExxaammpplleess;; ccuutt rreessiissttaanntt gglloovveess//sslleeeevveess,, bbuuttyyll gglloovveess,,ssaaffeettyy ggllaasssseess,, hhaarrdd hhaatt//bbuummpp ccaapp,, ffaallll pprrootteeccttiioonn,, eelleeccttrriiccaall PPPPEE aanndd aarrcc ffllaasshhccllootthhiinngg)).. AALLWWAAYYSS rreeffeerr ttoo aapppprroopprriiaattee SSaaffeettyy DDaattaa SShheeeettss ((SSDDSS)) aanndd OOSSHHAAgguuiiddeelliinneess ffoorr pprrooppeerr PPPPEE..

•• WWhheenn wwoorrkkiinngg wwiitthh oorr aarroouunndd hhaazzaarrddoouuss cchheemmiiccaallss,, AALLWWAAYYSS rreeffeerr ttoo tthheeaapppprroopprriiaattee SSDDSS aanndd OOSSHHAA//GGHHSS ((GGlloobbaall HHaarrmmoonniizzeedd SSyysstteemm ooff CCllaassssiiffiiccaattiioonn aannddLLaabbeelllliinngg ooff CChheemmiiccaallss)) gguuiiddeelliinneess ffoorr iinnffoorrmmaattiioonn oonn aalllloowwaabbllee ppeerrssoonnaall eexxppoossuurreelleevveellss,, pprrooppeerr rreessppiirraattoorryy pprrootteeccttiioonn aanndd hhaannddlliinngg iinnssttrruuccttiioonnss..

•• IIff tthheerree iiss aa rriisskk ooff eenneerrggiizzeedd eelleeccttrriiccaall ccoonnttaacctt,, aarrcc,, oorr ffllaasshh,, tteecchhnniicciiaannss MMUUSSTT ppuuttoonn aallll PPPPEE iinn aaccccoorrddaannccee wwiitthh OOSSHHAA,, NNFFPPAA 7700EE,, oorr ootthheerr ccoouunnttrryy--ssppeecciiffiiccrreeqquuiirreemmeennttss ffoorr aarrcc ffllaasshh pprrootteeccttiioonn,, PPRRIIOORR ttoo sseerrvviicciinngg tthhee uunniitt.. NNEEVVEERR PPEERRFFOORRMMAANNYY SSWWIITTCCHHIINNGG,, DDIISSCCOONNNNEECCTTIINNGG,, OORR VVOOLLTTAAGGEE TTEESSTTIINNGG WWIITTHHOOUUTT PPRROOPPEERREELLEECCTTRRIICCAALL PPPPEE AANNDD AARRCC FFLLAASSHH CCLLOOTTHHIINNGG.. EENNSSUURREE EELLEECCTTRRIICCAALL MMEETTEERRSS AANNDDEEQQUUIIPPMMEENNTT AARREE PPRROOPPEERRLLYY RRAATTEEDD FFOORR IINNTTEENNDDEEDD VVOOLLTTAAGGEE..

WWAARRNNIINNGGFFoollllooww EEHHSS PPoolliicciieess!!FFaaiilluurree ttoo ffoollllooww iinnssttrruuccttiioonnss bbeellooww ccoouulldd rreessuulltt iinn ddeeaatthh oorr sseerriioouuss iinnjjuurryy..

•• AAllll TTrraannee ppeerrssoonnnneell mmuusstt ffoollllooww tthhee ccoommppaannyy’’ss EEnnvviirroonnmmeennttaall,, HHeeaalltthh aanndd SSaaffeettyy((EEHHSS)) ppoolliicciieess wwhheenn ppeerrffoorrmmiinngg wwoorrkk ssuucchh aass hhoott wwoorrkk,, eelleeccttrriiccaall,, ffaallll pprrootteeccttiioonn,,lloocckkoouutt//ttaaggoouutt,, rreeffrriiggeerraanntt hhaannddlliinngg,, eettcc.. WWhheerree llooccaall rreegguullaattiioonnss aarree mmoorreessttrriinnggeenntt tthhaann tthheessee ppoolliicciieess,, tthhoossee rreegguullaattiioonnss ssuuppeerrsseeddee tthheessee ppoolliicciieess..

•• NNoonn--TTrraannee ppeerrssoonnnneell sshhoouulldd aallwwaayyss ffoollllooww llooccaall rreegguullaattiioonnss..

CopyrightThis document and the information in it are the property of Trane, and may not be used orreproduced in whole or in part without written permission. Trane reserves the right to revise thispublication at any time, and to make changes to its content without obligation to notify anyperson of such revision or change.

TrademarksAll trademarks referenced in this document are the trademarks of their respective owners.

Revision History• Updated the Overview of this Guide, Chiller Plant Types, Selecting Hardware and Equipment,

Commissioning and Programming, Sequences of Operation, Special Applications,Troubleshooting Resources and Glossary chapters.

• Added Appendix: Communicating Information Between Multiple SCs as a new chapter.

• Minor edits to document.

IInnttrroodduuccttiioonn

4 BAS-APG037D-EN

Overview of this Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Description of the CPC Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

What’s New? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

End-users and Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Chiller Plant Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Chiller Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Refrigeration Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Types of Condensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Chiller Plant Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12All Chiller Plant Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Chiller Piping Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Constant Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Parallel Chillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Series Chillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Stepped Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Decoupled Loop (Primary-Secondary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Variable Primary Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Selecting Hardware and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Chiller Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Trane Chiller Controllers (UC800 and Symbio 800) . . . . . . . . . . . . . . . . . . . . . . . . . 21Tracer AdaptiView™. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21CH530 Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Third-Party Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Cooling Towers, Pumps, Isolation Valves, Sensors . . . . . . . . . . . . . . . . . . . . . . . . . 21

Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Differential Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Flowmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Control Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Cooling Towers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Commissioning and Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Commissioning Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Unit Control Commissioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24High Level Checkout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Point-to-Point Checkout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Configuration and Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26PC and Software Required for System Configuration . . . . . . . . . . . . . . . . . . . . . . . 26

Table of Contents

BAS-APG037D-EN 5

Installing Chillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Creating a Chiller Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Where to Find Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Creating the Chiller Plant in Tracer Synchrony . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Making Chiller Plant Configuration Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Sequences of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Chiller Plant System Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Chiller Plant Start-Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Soft Start Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Transitioning into and out of Soft Start Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Add Sequence in Soft Start Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Rapid Power Failure Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Checking for Rapid Power Failure Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Rapid Power Failure Recovery Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Ambient Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

System Chilled Water Request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Chiller Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Normal (Temperature-based) Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Efficiency-based Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Chiller Add . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Add Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Normal Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Soft Start Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Efficiency-based Add . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Chiller Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Chiller Subtract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Subtract Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Efficiency-based Subtract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Chiller Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Chiller Plant Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Chiller Setpoint Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Constant Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Stepped Flow, Variable Primary Flow, and Decoupled Loop. . . . . . . . . . . . . . . . . 55Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Unload at Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Chiller Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Base Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Peak Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

TTaabbllee ooff CCoonntteennttss

6 BAS-APG037D-EN

Swing Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Pony Chiller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Chiller Plant Control Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Chiller Available/Unavailable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Special Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Where to find TGP2 Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Enabling a Chiller Plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Variable Primary Flow Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Calculating flow across a chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62How to Control the Bypass Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Writing TGP2 Programs Across Multiple Tracer SC+ Controllers . . . . . . . . . . . . . . . . 64

Troubleshooting Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Sequence of Operations Flow Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Chiller Plant Enable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Soft Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Rapid Power Failure Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Ambient Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71System Pump Start. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72Add Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Chiller Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Subtract Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Chiller Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76System Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78System Pump Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

System Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Chiller Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Order of Events in Adding and Subtracting Chillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Appendix: Communicating Information Between Multiple SCs . . . . . . . . . . . . . . . 85Sharing Data Between Two Tracer SC+s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Sharing Data Using the Pull Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Sharing Data Using the Push Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

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BAS-APG037D-EN 7

Overview of this GuideTo effectively design or control a chiller plant, it is helpful to understand concepts that go beyondthe scope of the system controller and down to the level of component selection and plantdesign concepts. This guide provides detailed information about the configuration,programming, and sequence of operation for the Tracer SC+ chiller plant control (CPC)application.

Description of the CPC ApplicationThe CPC application is a software application built into Tracer SC+. The application permits youto configure a chiller plant for efficiency and reliability and provides a means for you to monitorand control the daily operation. Depending upon the many possible chiller plant configurationsand design differences, the CPC application can do the following:

• Provide overall chiller plant status information and alarms to local and remote Tracer SC+users.

• Enable or disable chiller plants.

• Start, stop, and monitor the status of system chilled water pumps.

• Calculate individual chilled water setpoints for individual chillers in series chiller plants.

• Request when chillers are added or subtracted according to building load requirements,chiller efficiency and user-specified add and subtract logic.

• Rotate chillers according to user-defined intervals.

• Remove chillers from the rotation in the event of failure or required service and reinstatechillers into the rotation when they are available.

What’s New?Beginning at Tracer SC+/Synchrony version 5.6, the following features were added to theexisting chiller plant control application. Refer to the dedicated sections of this manual foradditional information on each new feature.

The new eeffffiicciieennccyy--bbaasseedd ssttaaggiinngg aallggoorriitthhmm was added to allow users to control their chillerplant based on the best efficiency point for adding and subtracting chillers.

The pre-built cchhiilllleerr ppllaanntt ccoonnttrrooll ddaasshhbbooaarrdd was added to show key performance indicatorsand chiller plant efficiency in accordance with ASHRAE Guideline 22 (when instrumentedappropriately) without needing to build a custom graphic.

The llooww lliimmiitt ccyycclliinngg aavvooiiddaannccee function was added to delay the application from starting anadditional chiller when a chiller cycles off at low loads.

The ffeeeedd ffoorrwwaarrdd ccoonnttrrooll function makes it easier to understand when a chiller is going to startor stop so the associated control can proactively respond, like opening the minimum flow bypassto increase flows prior to starting a chiller.

The new ppoonnyy cchhiilllleerr designation allows the installer to easily identify a chiller as a “Pony”chiller, specifically defined to handle night loads or low load conditions.

The new ggrraapphhiiccaall uusseerr iinntteerrffaaccee eennhhaanncceemmeennttss simplify the system selection andconfiguration options for the installer setting up the chiller plant in Tracer Synchrony.

End-users and ObjectivesEnd-users who may benefit from the information in this guide:

• CCoonnttrrooll ssyysstteemm ddeessiiggnn eennggiinneeeerrss for help with plant design.

• PPiippee ffiitttteerrss,, mmeecchhaanniiccaall ccoonnttrraaccttoorrss,, eelleeccttrriicciiaannss for help with installation.

• BBAASS tteecchhnniicciiaannss for help with verification and equipment setup, programming,commissioning, and optimization of the chiller plant.

• AAiirr//wwaatteerr bbaallaannccee ccoonnttrraaccttoorrss for help with commissioning.

8 BAS-APG037D-EN

• BBuuiillddiinngg ooppeerraattoorrss for help with daily operation.

• SSeerrvviiccee tteecchhnniicciiaannss for help with troubleshooting.

Following are the high-level objectives for this guide:

• Identify the chiller plant type and have a general understanding of how it functions.

• Identify the chiller type and understand any non-standard operation it may entail.

• Identify and correct system design problems that may cause future system problems.

• Set up secondary controls and equipment related to the chiller plant.

• Set up the chiller plant in the Tracer Synchrony user interface.

• Perform standard chiller plant operational procedures.

• Understand and set up special applications such as variable primary flow systems.

• Troubleshoot the chiller plant related or unrelated to the system controller.

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BAS-APG037D-EN 9

Chiller Plant TypesThe purpose of this section is to provide a detailed description of chiller plants and theassociated chillers. the following topics are covered:

• Type of chillers and chiller plants that could be in your facilities.

• Why the chillers or chiller plants may have been selected for your facilities.

• Some of the overall characteristics of the chillers or chiller plants.

Chiller TypesRefrigeration Method

All refrigeration methods involve adding energy to a refrigerant, then releasing the stored energyand taking advantage of the ability of a refrigerant to absorb and reject heat while it changesfrom one state to another.

Vapor CompressionVapor compression chillers compress refrigerant vapor from low to high pressure. The highpressure vapor is passed through the condenser where the vapor is condensed. As it condenses,the refrigerant transfers heat to the air or cooling water, which ultimately rejects the heat to theatmosphere.

The refrigerant undergoes a pressure drop as it passes through an expansion device. Thepressure drop causes the liquid to vaporize and absorb heat from the water as the water passesthrough the chiller. There are four main types of vapor compression chillers (see Figure 1, p. 10in this section):

• RReecciipprrooccaattiinngg — Single compressor chillers are typically available in capacities up to 100tons. Multiple compressors can be installed in a single chiller to increase capacity to up to 200tons.

• SSccrroollll — Scroll compressors are 10 to 15 percent more efficient than reciprocatingcompressors and are more reliable because they have 60 percent fewer moving parts. Unitsup to 15 tons can be hermetically sealed and multiple compressors can be installed in a singlechiller to increase capacity to up to 200 tons.

• HHeelliiccaall--rroottaarryy ((ssccrreeww)) — Historically used in air compression and low-temperaturerefrigeration applications. Currently, helical-rotary compressors are widely used in medium-sized water chillers from 50 to 500 ton capacity.

• CCeennttrriiffuuggaall — Popular due to their high efficiency, high capacity, and reliability. Centrifugalchillers are also relatively low in cost and noise compared to other chiller types. They can bepre-fabricated in sizes from 100 to 3000 ton, but can also be built on site in sizes up to 8500tons.

10 BAS-APG037D-EN

Figure 1. Vapor compression compressor types

ScrollReciprocating

Helical-rotary Centrifugal

AbsorptionAbsorption water chillers use heat instead of a compressor to provide energy that drives therefrigeration cycle. Steam, hot water, burning oil, or natural gas are the most common energysources for these types of chillers. There are three main types of absorption chillers (see Figure2, p. 11 in this section).

• IInnddiirreecctt,, ssiinnggllee--eeffffeecctt absorption chillers operate on low-pressure steam (15 psig [894 kPa])or medium-temperature liquids (270°F [132°C]). In many applications, the energy source iswaste heat from process loads, cogeneration plants, or excess boiler capacity. As a result, thechillers are conservation devices that operate as the lead chiller to make use of energy thatmight otherwise be lost.

• DDoouubbllee--eeffffeecctt absorption chillers use medium-pressure steam (115 psig [894 kPa]) or high-temperature liquids (370°F [188°C]); a dedicated boiler is generally required.

• DDiirreecctt--ffiirreedd absorption chillers have an integral burner so they can burn one or more fossilfuels directly (natural gas, fuel oil, or liquid petroleum).They do not affect electrical peak-demand energy rates and they can also be used to produce hot water for heating, whichreduces boiler demand.

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BAS-APG037D-EN 11

Figure 2. Absorption chiller types

Double-EffectSingle-Effect

Direct-Fired

Types of CondensingWWaatteerr--CCoooolleedd HHeeaattiinngg

Water conveys heat from the refrigerant to the outside atmosphere in water-cooled condensingsystems, which range from 10 to 3000 ton cooling capacity. It is fundamentally a more efficientcondensing method than air-cooled condensing because the refrigerant condensing temperatureis based on the ambient wet-bulb temperature, which is lower than the ambient dry bulbtemperature. A lower condensing temperature requires lower condensing pressure, whichconsumes less energy.

Figure 3. Water-cooled condensing

However, water-cooled condensing efficiency is a smaller advantage in part-load conditions andwhen pump energy is considered. Likewise, installation and maintenance costs are higher withwater-cooled condensing.

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Air conveys heat from the refrigerant to the outside atmosphere in air-cooled condensingsystems, which range from 7.5 to 500 ton cooling capacity. While these systems arefundamentally less efficient than water-cooled condensing systems, they can be a better choicein smaller systems that are primarily under-utilized, where freezing is a factor due to the climateor where maintenance (condenser tube cleaning and tower mechanical service) is prohibitivelydifficult or expensive. For process applications such as computer centers that require cooling incold climates year-round, the ability to run in sub-freezing temperatures is sometimes the singledetermining factor in opting for an air-cooled condensing system.


12 BAS-APG037D-EN

Figure 4. Air-cooled condensing

Chiller Plant TypesThe name of a specific chiller plant type provides an idea of the piping configuration: the locationand types of pumps, valves, and sensors, and the principles of operation.

The type of chiller plant designed significantly affects:

• The up-front cost of labor, materials, and equipment.

• The energy efficiency of the plant once it is up and running.

• The performance and capacity limitations of the chiller plant.

• The ease or difficulty of programming, operating, maintaining, and troubleshooting thechiller plant.

If you are working with an existing chiller plant, it is imperative that you know the plant type inorder to properly configure the system controller and operate the plant.

Though there are an unlimited number of variations between one chiller plant and another, thereare four basic types:

• Constant Flow

• Stepped Flow

• Decoupled loop (primary/secondary)

• Variable Primary Flow

All Chiller Plant TypesA typical chiller plant consists of at least one chiller, one pump, piping to circulate chilled waterto the load, two temperature sensors (one for return water and one for supply water), andmultiple sensors and valves that permit monitoring and control of the plant. Figure 5, p. 13shows the basic arrangement of a generic chiller plant.

NNoottee:: Assume that “water” can refer to other fluids that are used in some applications.


BAS-APG037D-EN 13

Figure 5. Basic chiller plant

Chiller Piping ArrangementWhen a chiller plant has more than one chiller, the chillers can be piped in parallel or in series.

ParallelA parallel chiller arrangement has multiple chillers that are piped in parallel. The water pipesupstream of the chillers branch out into separate pipes that later rejoin downstream of thechillers.

Figure 6. Three parallel chillers

ManifoldingEach chiller in a parallel chiller plant can have a dedicated pump directly upstream from it or amanifold may exist that separates the pumps from the chillers. Manifolding can entail a morecomplicated control strategy, but usually provides redundancy of chiller pumps.


14 BAS-APG037D-EN

Figure 7. Three parallel chillers with dedicated pumps Figure 8. Three chillers with three manifolded pumps

SeriesA series chiller plant has two or more chillers that are piped in-line with each other. Water entersthe first chiller where it receives its first stage of cooling. It then enters the second chiller where itis chilled to an even lower temperature. System water will flow through every chiller in a seriesplant.

Figure 9. Series chillers

Constant FlowConstant flow plants always flow water through all chillers regardless of the operational status ofthe chiller. Here are some considerations for constant flow chiller plants:

• If parallel chillers are used, the Chilled Water Setpoint for running chillers must be calculatedto compensate for non-running chillers to maintain the System Chilled Water Setpoint.

• They are the least energy efficient of the plant types:

– Pump energy is wasted pumping through non-operational chillers.

– Operational chillers run at a higher duty cycle level to compensate for non-runningchillers.

• They have a relatively low first-cost because of minimal piping and equipment requirements.

• The most common usage for constant flow chiller plants are smaller facilities with twochillers.

• Chiller plants with only one chiller are considered to be constant flow.

• Three-way valves must be installed at the building load coils.

Parallel ChillersFor the chiller plant type shown in Figure 10, p. 15, only one pump runs at a time and it pumpswater through both chillers, even when they are not both running. For instance, if each chiller hasa maximum flow rate of 250 gpm (950 lpm), each pump must be able to pump 500 gpm (1900lpm).


BAS-APG037D-EN 15

• The primary advantage is protection against pump failure and lower equipment, materials,and labor costs.

• The disadvantages are low efficiency when fewer than all of the chillers are running at thesame time: pump energy is wasted by pumping water through chillers that are off, andoperational chillers must have lower set-points to compensate for warm water that passesthrough the non-operational chillers.

NNoottee:: You could also use a single pump with this configuration, but in that case, pump failureshuts down the plant.

Figure 10. Constant flow, parallel manifolded chillers

Series ChillersFor the chiller plant type illustrated in Figure 11, p. 15, there is one pump that runs all of the time.Typically the first chiller (closest to the pump outlet) has a chilled water setpoint that is higherthan the set-point of the next chiller.

Figure 11. Constant flow, series chillers


16 BAS-APG037D-EN

Stepped FlowStepped Flow plants only flow water through chillers that are running. Isolation valves ordedicated pumps are used to prevent flow through non-running chillers.

Following are considerations for stepped flow chiller plants:

• The System Chilled Water Setpoint is the Chilled Water Setpoint for all of the chillers.

• They are more efficient than constant flow chiller plants:

– They do not expend pump energy pumping water through non-running chillers.

– Running chillers do not need to compensate for non-running chillers.

• When comparing first cost to constant flow chiller plants with parallel chillers:

– Lower capacity pumps can be used, which are significantly less expensive.

– If the pumps are manifolded, isolation valves must be used.

– Manifolding pumps provides redundancy: a chiller is not paired with a pump, so anychiller can be run with any pump, and adding an extra pump provides even greaterredundancy.

• Typically, stepped flow chiller plants require higher first-cost than constant flow due toadditional equipment and installation requirements (pump, VFD, flowmeter, wiring, and soforth.).

• Three-way valves must be installed at the building load coils.

Figure 12. Parallel stepped flow examples

Decoupled Loop (Primary-Secondary)• The primary loop, also called the production loop, includes the chillers.

• The secondary loop, also called the distribution loop, contains the load.


BAS-APG037D-EN 17

Figure 13. Primary and secondary loops

In a decoupled loop, each loop has its own pump(s). As the name implies, each loop is anindependent system that has practically no controls-based connection to the other loop.

• The primary loop is responsible for maintaining the System Chilled Water SupplyTemperature. Chillers are added or subtracted according to the add and subtract logic in theCPC application. Pumps in the primary loop are constant speed pumps that run to maintainflow through the chiller(s).

• The secondary loop is responsible for distributing the chilled water through the building load.Pumps in the secondary loop are variable speed. They increase flow in response to decreasedpressure drop across the building load, and decrease flow in response to an increase inpressure drop across the load to ensure that enough, but not too much, chilled water is madeavailable to the load.

• Two-way valves must be installed at the building load coils.


18 BAS-APG037D-EN

Figure 14. Decoupled loop examples

• The bypass pipe mitigates the difference in flow rate between the primary and secondaryloops:

– As the load demand increases and the secondary loop pump speeds up, the secondarypump output will begin to exceed the primary loop flow rate. This causes warm returnwater to be drawn through the bypass to make up the flow deficit in the primary loop. Thisstate is commonly referred to as deficit flow.

Figure 15. Deficit flow example

– As the load demand decreases and the secondary loop pump slows down, the secondarypump output will begin to fall short of the primary loop flow rate. This causes excesschilled water flow to be diverted through the bypass. This state is commonly referred toas excess flow.


BAS-APG037D-EN 19

Figure 16. Excess flow example

Variable Primary FlowA Variable Primary Flow plant type is a variation of the Stepped Flow plant type. Rather thanusing a primary-secondary configuration with variable speed pumps on the secondary loop, onlya primary loop with variable speed pumps is used. Variable primary flow plants have a bypasspipe that is only used in low flow situations. The bypass pipe is sized for the minimum flow rateof the highest-capacity chiller in the plant. In addition, the bypass pipe must have a modulatingvalve installed to maintain minimum flow through the chillers' evaporators.


20 BAS-APG037D-EN

Figure 17. Basic variable primary flow examples

Notes about variable primary flow:

• Under typical operating conditions, the bypass valve is closed.

• Flow through the bypass can only go one direction (supply-to-return).

• Two-way valves must be used at the building load coils.

Advantages:

• Typically more efficient than constant flow or non-primary variable flow.


BAS-APG037D-EN 21

Selecting Hardware and EquipmentUse this section to help select controllers, sensors, or valves for your chiller plant. Theinformation here may help you select the hardware for your chiller plant or identify the hardwarethat has already been selected. The type of hardware used can significantly affect chiller plantperformance, efficiency, and ease of use.

Chiller ControllersThere are many possible chiller controllers made by Trane and other vendors. For detailedinformation, refer to the documentation provided with the controller.

Trane Chiller Controllers (UC800 and Symbio 800)The building design engineer selects the chillers in a chiller plant according to the needs of theparticular application in which they will be used. The controllers are bundled with the chillersbased on the chiller type; chillers and controllers cannot be selected separately.

Tracer AdaptiView™™The Tracer AdaptiView™ display provides a means for viewing data and for making operationalchanges on simplex and duplex CenTraVac chiller models. It uses the BACnet communicationprotocol by default, but can also be used with LonTalk networks with the addition of an LCI-C (aLonTalk Controller Interface for Chiller controllers).

CH530 ControllerThe Trane CH530 controller is widely used. It can use the BCI-C (BACnet Control Interface forChillers) in a BACnet network (at 76.8 Kbps on the MS/TP link) and using the nine BACnet pointtypes: AI, AO, AV, BI, BO, BV, MI, MO, and MV. It can also use the LCI-C (LonTalk CommunicationInterface for Chillers) in a LonTalk network.

NNoottee:: The LCI-C must have the correct firmware to communicate with the controller on the chiller.

Third-Party ChillerTracer SC+ supports third-party chillers that use either LonTalk or BACnet MS/TP or BACnet/IPprotocols. If the third-party chiller natively communicates using an alternate protocol (Modbus ora proprietary protocol), a gateway must be used to convert the alternate protocol to eitherBACnet or LonTalk protocols.

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When choosing the communication protocol, there are several important factors to consider:

• If it is an existing installation, determine the protocol that is currently in use. If the existinginstallation is wired for one protocol or the other, it is easier and more economical tocontinue with the same protocol.

• The protocol that is available at the lowest cost (for example, UC800 and Symbio 800controllers natively use BACnet protocol and can only use LonTalk with an additionalinterface).

• The protocol that is required by the design specification.

• Third-party integration considerations — some components in the system may work betterwith a specific protocol.

NNoottee:: Tracer SC+ can support BACnet and LonTalk protocols simultaneously; however, it issimpler, less costly, and easier to install a chiller plant that uses only one protocol.

Cooling Towers, Pumps, Isolation Valves, SensorsThese systems are typically managed by field-installed and programmed programmablecontrollers. The number and type of controllers is a factor when considering the number ofpoints on the devices. Frequently, controllers are split by subsystem type (for example, chilledwater system, condenser water system, cooling tower).

22 BAS-APG037D-EN

• MP580/MP581 - LonTalk controller - configured and programed using Rover (TGP)

• UC600 - BACnet controller - configured and programmed using Tracer TU (TGP2)

SensorsTemperature

TypesTemperature sensors measure System Chilled Water Return Temperature, System Chilled WaterSupply Temperature, condenser water temperature, outdoor air temperature, and air handlerdischarge air. Temperature sensors are inserted into thermowells where they measuretemperature in piping. they are used without thermowells for air temperature.

It is important to use very accurate sensors whenever possible due to the high cost of startingchillers. ASHRAE Guideline 22 provides guidance for selecting temperature sensors. Considerthe following:

• Most Trane controllers support thermistor inputs of 10,000 ohms @ 77°F (25°C).

• Some Trane controllers support RTD sensors, specified at 1000 ohms @ 0°C (385 curve).

• For all types of sensors, use conductive thermopaste when installing sensors in thermowells.

Differential Pressure

SwitchesDifferential pressure switches can be used for air or water. They must be the correct type for theapplication. They are typically used for:

• pump proof.

• proof of flow across chillers.

• supply or exhaust fan proof.

NNoottee:: In all cases, ensure that the switch fits the pressure range for the application.

TransmittersDifferential pressure transmitters can be used for air or water. They are typically used on thewater side for pressure drop across chiller bundles to calculate flow rate. They can be also usedon the secondary (distribution) loop differential pressure to determine the required run speed forthe variable frequency drives on chilled water pumps.

Current

Switches (Binary)Current switches are used for similar applications as the differential pressure switches. They areused primarily on pumps and fans. They measure the current through a conductor. Becausethese sensors measure current flow, they can detect mechanical failures such as shearedcouplers on pumps and broken fan belts.

Transmitters (Analog)Current transmitters are not typically used, but when used they can read the amperage at whicha device is operating. They can infer the operational status of a device, or, for example, report thecurrent draw of each power leg of a chiller.

Flowmeters

UltrasonicUltrasonic flowmeters are typically the most accurate but also the most expensive option formeasuring flow rate. They use an ultrasonic transducer, and as a result have no moving partsand are less likely to require service or maintenance.

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BAS-APG037D-EN 23

MechanicalMechanical flowmeters are available in many varieties. Among them, the most commonly usedin chiller plants are paddle wheel and turbine. They tend to be the least expensive but they arealso less accurate because they have moving parts and more likely to wear out. They also tend tobe more difficult to locate in the piping because they typically need long pipe runs ahead ofthem.

Pressure-BasedThese meters create a pressure drop across an orifice plate and use the differential pressuremeasurement across the pressure drop to determine the flow rate. Measuring the pressurereadings across a chiller bundle provides an accurate means of determining flow rate.

Control ValvesTypes

BallBall valves are used for shut off or modulating control applications, such as cooling or heatingcoils, on smaller diameter pipes.

GlobeGlobe valves are used for modulating control applications, such as cooling or heating coils, onlarger diameter pipes where ball valves cannot be used.

ButterflyButterfly valves are used on large-diameter piping in shut off applications, such as chillerisolation valves, and tower isolation valves. They are not typically used for modulatingapplications.

Two-Way and Three-WayTwo-way valves are typically used on stepped flow systems that modulate the flow based uponsystem pressure. Three-way valves are typically used on constant flow systems.

PumpsPumps move chilled water and condenser water through chilled water systems. They aretypically provided by the mechanical contractor and not the controls contractor. There are manyvarieties of pumps, but centrifugal pumps are most commonly used in chilled water systems.

Cooling TowersCooling towers are used only for water-cooled chillers. The condenser water loop is separatefrom the chilled water loop and removes heat from the refrigeration cycle. Closed loop systems,in which the water is sealed off from the atmosphere, are less common than open loop systems,which permit the condenser water to be exposed to the atmosphere. Open systems, becausethey are exposed to the environment, must use chemically treated water. In typical HVACapplications, cooling towers use electrically powered forced air rather than natural draft.

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24 BAS-APG037D-EN

Commissioning and ProgrammingUse the following as a checklist to prepare a chiller plant for operation.

Commissioning SummaryCommissioning and programming a chiller plant should include all of the following, which areexplained in this section and in other parts of this guide, as indicated.

1. Carefully review the entire sequence of operations in the design specification.

2. Become familiar with the control submittal.

3. Perform the unit control commissioning (see “Unit Control Commissioning,” p. 24).

4. Complete checkout of programs before you program the CPC application.

a. Read the entire sequence of operation.

b. Separate the sequence into small pieces, and then program and test each pieceseparately. For example, chilled water request turns on a pump, then add failures forpump, then add rotation.

c. Identify any existing programs you can download and use, and if so, download them.

5. Install the chillers and unit controllers into Tracer SC+ (see “Installing Chillers,” p. 26).

6. Create the chiller plant in Tracer Synchrony (see “Creating a Chiller Plant,” p. 30).

7. Write/install any required TGP2 programming to meet sequences of operation (see “SpecialApplications,” p. 60.)

8. Verify that the system meets all sequences of operation.

Unit Control CommissioningTest and commission each subsystem. Use the following as an example:

1. Enable a pump.

2. Fail the pump by turning off the disconnect.

3. Verify that the replacement pump started.

High Level Checkout1. Verify that the control installation has been completed.

2. Verify that the electrical installation has been completed.

3. Verify that the mechanical installation has been completed.

4. Verify that the Trane Service Department has completed or is scheduled for factory chillerstartup.

5. Apply power to the controllers; for example the MP580s or UC400s. To be initially completedonly by the electrician responsible for the electrical installation.

6. Program points (or download the configuration) to the controllers.

7. Perform point-to-point checkout.

Point-to-Point CheckoutIImmppoorrttaanntt:: Do not energize equipment until both the electrical and mechanical contractors

confirm that it is safe to do so.

1. Verify temperature sensors. Typically short out sensor or other physical verification of thesensor wiring in the absence of a running application. In particular, make sure that eachsensor is physically terminated and installed in the correct place per its configuration.

2. Verify correct pump operation:

NNoottee:: Pump verification should have been performed by the electrical or mechanical contractor,but must be rechecked by the BAS technician during point-to-point checkout.

BAS-APG037D-EN 25

a. Confirm with mechanical and electrical contractor that pump(s) are ready to run.

b. Verify manual isolation valves are open.

c. Turn on the pump disconnect switch.

d. “Bump the Pump” to check the pump rotation: place the hand/off/auto switch to HANDoperation momentarily to verify that it is rotating in the correct direction as indicated bythe arrow on the pump housing.

e. Place the pump hand/off/auto switch on AUTO.

f. Confirm that the control start/stop command is in working operation. For constant volumepumps, override the start/stop command to START to verify; similarly, for variable speedpumps, override the start/stop command to START, and then override the speedreference to 50 percent and 100 percent, verifying each speed.

g. Calibrate and verify the pump proof operation - check both on and off states. For DPpressure switch or a current switch, a normally open (NO) contact is always used, whichmeans the switch is open when there is no flow and closed when there is measurableflow. The purpose of this calibration procedure is to establish the minimum measurableflow.

i. Start the pump.

ii. For variable speed pumps, make sure the pump is running at the motor minimum-rated speed.

iii. Adjust the sensor until the contact opens, and then adjust it slightly in the otherdirection until the contact closes again.

NNoottee:: When using DP switches, ensure that any pet cocks used for isolating the DP switch areopen and if there is another device, such as a pressure gauge sharing common pipework, make sure that any other valves are configured properly to ensure a differentialpressure reading across the DP switch.

h. For variable frequency pumps, verify the analog output scale (typically 4-20 mA) iscorrectly mapped to the analog input scale on the variable frequency drive.

IImmppoorrttaanntt:: It is possible to configure the output scale according to the frequency (0 to 50/60Hz) or percentage (0 to 100%). It is important to make sure that all programsand equipment keys use the same scale selection.

3. Verify cooling towers:

Verify the operation of the fans in the cooling tower(s) in the same way as pumps are verifiedusing a current switch.

IImmppoorrttaanntt:: Do not switch a fan from high speed to low speed instantaneously! Switching a fanfrom high speed to low speed instantaneously can destroy the drive gear. Turn thefan off and wait for it to slow down before turning it on at low speed.

4. Isolation valves:

a. Open-Closed valves:

i. Send the OPEN command to the valve.

ii. Visually verify the valve opened (inspect the valve indicator).

iii. If optional in switches are used, verify the open in switch responded appropriately.

iv. Send the CLOSED command to the valve.

v. Visually verify the valve closed (inspect the valve indicator).

vi. If optional in switches are used, verify the closed in switch responded appropriately.

b. Modulating valves

i. Drive open and verify.

ii. If optional in switches or position feedback are used, verify the open in switchresponded appropriately.

iii. Drive closed and verify.

CCoommmmiissssiioonniinngg aanndd PPrrooggrraammmmiinngg

26 BAS-APG037D-EN

iv. If optional in switches or position feedback are used, verify the closed in switchresponded appropriately.

v. Drive to 50% open and verify.

vi. If position feedback is used, verify the correct valve position is appropriately reported.

5. Have the Trane Service Department perform a factory startup of each chiller.

Configuration and ProgrammingUse this section when installing chillers into Tracer SC+, creating a chiller template, and creatinga chiller plant.

PC and Software Required for System ConfigurationTo configure your system, you must use a PC with the following software installed:

Requirement Purpose Where to Get It

The most recent version of webbrowsers are tested with each newfirmware release and will providethe best user experience. Utilizationof other operating systems andbrowsers may work given ouradherence to web standards, butthis is not recommended/supported.Microsoft®®Windows 10

• Google Chrome

• Mozilla Firefox

• Microsoft Edge (chromium)Apple®®Mac OS (most recentversion)

• Google Chrome

• Mozilla Firefox

Tracer Synchrony providesinformation in HTML pages forviewing in an internet browser.

Download and install from MicrosoftCorporation or Mozilla, respectively.

Tracer TU Service Tool with acontroller basic license and a chillerlicense.

The tool is needed to performmanyfunctions, such as configuring allTrane BACnet devices, downloadingTracer Synchrony software updates,accessing Tracer Graphics Editor,and creating TGP2 programs.

Obtain from your Trane salesrepresentative.

Tracer TU Service Tool USB driver.

The driver is required forcommunication directly between thePC Universal Serial Bus and TracerSC+, Symbio 800 controller, or theUC800 controller.

Installed with Tracer TU Service tool.

The Rover Service Tool.

The tool is needed to configureLonTalk® unit controllers, managethe LonTalk network, and create TGPprograms for the Tracer MP580 and581 programmable controller.


KestrelView Software.The tool is used to configure theCH530 controller used on mostTrane chillers using an LCI-C.


Unlisted third-party software.

For systems with configurable/programmable components forwhich the tools listed elsewhere inthis table cannot be used.

Obtain from the manufacturer or thevendor of the third-partycomponents.

Installing ChillersTo install chillers in Tracer SC+:

1. Ensure that the communication wiring is properly completed.

2. Verify that the power has been applied to the controllers.


BAS-APG037D-EN 27

3. For BACnet chillers:

• For Trane BCI-C chillers, verify that the rotary address is set.

• For Trane UC800 or Symbio 800 chillers that communicate on the MS/TP link or BACnet/IP,verify that the rotary address is set and the BACnet device ID is unique within the facility.

• For non-Trane BACnet controllers, verify that the BACnet Device ID is unique within thefacility.

• For all BACnet MS/TP chillers, ensure that all devices in the link have the same baud rate.

4. For LonTalk chillers, commission the LonTalk link using the Rover Service Tool or a third-party LonTalk network management tool.

5. Initiate chiller discovery on the Discover Devices page in the system controller user interfacefor the appropriate communication link.

6. After the chillers have been discovered, click IInnssttaallll DDeevviicceess , which opens the DDeeffiinneeEEqquuiippmmeenntt ffoorr DDeevviicceess page.

They will either be automatically assigned to a template, or they will need to be manuallyassigned:

• Trane chillers that have been automatically assigned will appear in the Ready to Installsection of the page. Other than optionally changing the names of the chillers, you should notneed to make any other adjustments to these chillers.

• Chillers that need to be manually assigned to a template will appear in the Define forInstallation section of the page. You must manually assign a template or map the objectsusing one of these two methods:

– Identify, locate, and select an existing template and apply the template to the chiller. Theexisting templates would have to have been created within this system controller orwould need to have been imported before the chiller was discovered. You must be certainthat the device and the template completely match to use this option. If you are notcertain that they match, use the next option instead.

– Create a new template by selecting the chiller, then select AAccttiioonnss >> CCrreeaattee TTeemmppllaatteefrom the device page. You can start with an existing template using the Select ExistingTemplate button and then make modifications to individual keys as needed, or you createa new template and map all of the keys one at a time. Table 1, p. 27 shows therecommended mapping for a generic chiller and what the applications use the data for.

IImmppoorrttaanntt:: It is important to make sure that you select the correct equipment family andequipment type or the chiller will not appear in the right place or be availableto be added to the chiller plant.

After a chiller is assigned to a template or the mapping process is completed, the chillerwill be moved to the Ready to Install section.

7. Click IInnssttaallll to complete the chiller installation.

Table 1. Recommended chiller template mappings

TracerSynchronyKey Name

Point Type Enumerations Usage Used By Notes

Active Cool/HeatSetpoint

TemperatureAnalog Input — Status

Chiller StatusPage

This value is alsodisplayed.

Active CurrentLimit Setpoint Analog Input — Status

ChillerConfigurationPage, CPCapplication

Used by CPCwhen unload atstart is enabled

Actual RunningCapacity Analog Input — Status


Used by CPC for“Subtract onCapacity”


28 BAS-APG037D-EN

Table 1. Recommended chiller template mappings (continued)



Capacity Limited Binary Inputinactive = Not

Limitedactive = Limited

StatusChiller Status

Page

Chiller Auto StopCommand BAS

(a)Binary Output Inactive = Stop

Active = AutoConfiguration

Chiller StatusPage, CPCapplication

Used by CPC tocontrol thechiller on or offbased on systemloads. This is theonly requiredmapping whencreating a chillerobject.

Chilled WaterSetpoint Analog Output — Configuration

Chiller Status,Page, ChillerConfigurationPage, CPC

application, CPCStatus Page

Used by CPC tocontrol thechiller chilledwater setpointfor each chiller.CPC willcalculate theappropriatesetpoint basedon the plant typeand systemchilled watersupply setpoint.

Chiller ModeCommand BAS

Multi-stateOutput

1 = Cooling2 = Heating

3 =Ice Building4 = Free Cool

ConfigurationChiller

ConfigurationPage

Chiller RunningState

Binary Input Inactive = OffActive = On Status

Chiller StatusPage

Binary value forchillercompressorstatus, this isnot used bychiller plantcontrol.

CondenserWater EnteringTemperature

Analog Input — StatusChiller Status

Page

CondenserWater FlowStatus


Page

CondenserWater LeavingTemperature


Page

Cooling Type Multi-stateInput

1 =WaterCooled

2 = Air CooledStatus

ChillerConfiguration

Page

Current LimitSetpoint Analog Output — Configuration


Used by CPCwhen unload atstart is enabled

Diagnostic LastMessage Binary Input String Status

Chiller StatusPage

DiagnosticPresent

Binary Input

Inactive =Normal

Active = InAlarm


Page


BAS-APG037D-EN 29

Table 1. Recommended chiller template mappings (continued)



DiagnosticShutdownPresent

Binary Input

Inactive =Normal

Active = InAlarm

StatusChiller StatusPage, CPCapplication

This value ismonitored bythe CPCapplication andwhen true failsthe chiller in theCPC application.

EvaporatorEntering WaterTemperature


Page

EvaporatorLeaving WaterTemperature

Analog Input — Status

Chiller StatusPage, CPCStatus Page,

CPC application.

Used by CPCapplication todetermine thechilled watersetpoint forseries chillerplants.

EvaporatorWater FlowStatus

Binary InputInactive = No

FlowActive = Flow


Used by CPC todetermine if thechilled waterflow has provenwhen CPCcontrols a chillerpump.

Local SetpointControl

Binary Input

Inactive =Remote controlActive = Local

control


Page

MaximumCapacity Binary Input Inactive = Off

Active = On StatusChiller Status

Page

Tells the userwhen the chilleris at maximumcapacity

Operating Mode Multi-stateInput

1 = Cooling2 = Heating

3 = Ice Building4 = Free Cool


Page

Outdoor AirTemperature Analog Input — Status

Chiller StatusPage

In some casesthe user maywant to use thisvalue for thefacility outdoorair temperature

Reset Diagnostic Binary OutputInactive =Normal

Active = ResetConfiguration

ChillerConfiguration

Page

Run Enabled Binary Input

Inactive = RunNot EnabledActive = RunEnabled


Page

Running Mode Multi-stateInput

1 = Chiller Off2 = Chiller InStart Mode3 = Chiller InRun Mode

4 = Chiller InPre-Shutdown

Mode5 = Chiller InService Mode


The CPCapplicationconsiders startand run to berunning all othermodes arestopped.


30 BAS-APG037D-EN

Creating a Chiller PlantWhere to Find Information

Before creating a chiller plant at the Tracer Synchrony user interface, review the followingrequirements:

Table 2. Where to find configuration information

Required Information Where to Find It — If Applicable

Chiller plant type “Chiller Plant Types,” p. 12

Performance specifications of the chillers related totonnage capacity and flow. Chiller documentation

If there is more than one chiller:

• What will be the chiller add logic parameters? “Add Logic,” p. 48

• Are the chillers parallel or series? “Three parallel chillers,” p. 13

• What will be the subtract method and subtract logicparameters?

“Subtract Logic,” p. 51

• What will be the rotation method? “Chiller Rotation,” p. 56

If there are three or more chillers, what roles will beassigned to the chillers: base, swing, or peak? Plant design

Does the CPC application need to control a systempump? Plant design

Will the chiller plant be using any of the following features?

• Efficiency-based Staging“Enable Efficiency-based Add Logic,” p. 39“Enable Efficiency-based Subtract Logic,” p. 39

• Ambient Temperature Lockout “Ambient Lockout,” p. 45

• Rapid Power Failure Recovery “Rapid Power Failure Recovery,” p. 45

• Soft Start “Soft Start Mode,” p. 43

• Feed Forward Control“Feed Forward Add Signal Time,” p. 39“Feed Forward Subtract Signal Time,” p. 39

• Limit Low Load Cycling “Limit Low Load Cycling,” p. 39

The names and logical locations of the references to be used for the following parameters:

• System Chilled Water SetpointLook for the design setpoint for the plant on thesequences of operation section of the designspecification.

• System Chilled Water Supply TemperatureIn the controls submittal or programmable controllerwhere the sensor is wired.

• System Chilled Water Return TemperatureIn the controls submittal or programmable controllerwhere the sensor is wired.

How quickly and at what notification class will the CPC application post system or chiller failures.

How the chiller plant should operate in the event of asystem or chiller failure.

“System Alarms,” p. 80 section and “Chiller Alarms,” p.81 section, Troubleshooting Resources chapter.

NNoottee:: The list above is general in nature. You will need to provide additional details when settingup the chiller plant. The settings can be changed after the plant is created, if necessary.


BAS-APG037D-EN 31

Creating the Chiller Plant in Tracer SynchronyTo create a chiller plant:

Tracer Synchrony leads you through the process of creating a chiller plant for your facility bynavigating through a series of steps and pages, often referred to as a "setup wizard."

• Create Chiller Plant – Define

• Create Chiller Plant – Select Chiller Plant Type

• Create Chiller Plant – Select the Chiller Plant Configuration

• Create Chiller Plant – Setup Chillers

• Create Chiller Plant – Configure Add/Subtract Methods

• Create Chiller Plant – System Setup

• Create Chiller Plant – Summary

Log in to Tracer Synchrony and navigate to SSyysstteemmss > CChhiilllleerr PPllaannttss > CCrreeaattee CChhiilllleerr PPllaanntt tostart the process. Complete each page in the process, and then click finish to save the chillerplant.

Define Chiller Plant

Figure 18. Create Chiller Plant—Define

Name, DescriptionProvide a name and meaningful description of the chiller plant.

UUssee CChhiilllleerr PPllaanntt ttoo ssttaarrtt uupp aanndd sshhuutt ddoowwnn ssyysstteemm cchhiilllleedd wwaatteerr ppuummppss

Select whether chiller plant control starts/stops the system (secondary) pumps of a primary/secondary chiller system. This selection is not application to the remaining plant types.

Enable Ambient Temperature Lockout FunctionSelect whether chiller plant control is disabled when the ambient temperature is below theambient lockout temperature.

After completing the setup wizard, the Ambient Temperature Lockout settings are presented inthe configuration options of chiller plant control. Edit the setpoint below which chiller operation


32 BAS-APG037D-EN

is locked out. Edit the deadband above which chiller plant operation is permitted (setpoint +deadband). For reference, the ambient temperature is displayed in the same grouping.

Figure 19. Ambient Temperature Lockout

Supports Rapid Power FailureSelect whether chiller plant control picks up where it left off after power failure. Left unchecked,chiller plant control will instead of sequence through the progression, observing all timers.

Enable Soft StartSelect whether chiller plant control delays staging of additional chillers upon enabling of theplant. The staging algorithm considers rate of change, interval timer, and deadband.

After completing the setup wizard, the Soft Start settings are presented in the configurationoptions of chiller plant control. Refer to the Soft Start section of this manual for additionalinformation on each of the settings.

Figure 20. Soft Start

Select the Chiller Plant TypeUse the radio buttons provided to select the chiller plant type.


BAS-APG037D-EN 33

Figure 21. Select the Chiller Plant Type

Select the Chiller Plant ConfigurationUse the radio buttons to select whether the configuration of the chiller plant is parallel or series.Identify the number of chillers for this plant and the pump configuration. Based on the type,number, and pump configuration, the available selections on the following setup pages will varyslightly.

Figure 22. Select the Chiller Plant Configuration


34 BAS-APG037D-EN

From each drop-down list, select the name of each chiller. When applicable, select the binarypump control (output) reference as well.

The order defined on this page is the order the chillers will appear on the dashboard graphic.

Figure 23. Chiller Plant Sequencer – Variable Primary Flow Chiller Plant

Setup Chillers

Configure MembersThe Chiller Type and Compressor type were determined automatically by the Tracer SC+ uponinstallation of the chiller controller.

Chilled Water Setpoint MinimumEdit the minimum chilled water setpoint for each chiller, as sent to the chiller by the chiller plantcontrol application. Separately (locally), each chiller has a minimum allowable setpoint.

Unload at StartWhen checked, chiller plant control will demand limit the running chiller(s) at the Unload CurrentLimit until the next chiller is added.

Unload Current LimitSee above.

Chiller Design CapacityCarefully enter the design (nameplate) capacity of each chiller. These values must be correct formost chiller plant control functionality to be accurate, especially for efficiency-based staging.

Total Run HoursEdit the run hours appropriately for existing chillers with run hours greater than zero.

Sequence TypesSelect from the available sequence types, then designate the chiller identified as such. Forexample, If Chiller 1 is the Swing Chiller, check the box for Swing Chiller, then Chiller 1 from thedrop-down list.


BAS-APG037D-EN 35

Base ChillerThe base chiller is always the first chiller on and the last chiller off (For example, if the chillerplant is enabled, the base chiller is enabled).

Peak ChillerThe peak chiller is always the last chiller enabled and the first chiller to be disabled. Often, thepeak chiller is an older or less efficient chiller that should run only if necessary.

Swing ChillerA swing chiller is 1/3 to 2/3 the size of the other chillers in the plant. It is the first chiller (if no baseexists) to be enabled and then alternates (enabled/disabled) with the remaining chillers in theplant. The purpose of a swing chiller system is to match the cooling capacity more closelygenerated by the chiller plant to the cooling load.

Pony ChillerA pony chiller is used at night or low-load conditions in lieu of applying the other chillers in theplant. The pony chiller is normally smaller than the others and sized to handle the low loadconditions. The pony chiller can also be configured to be added as the last chiller in the sequencewhen additional capacity is needed.

Figure 24. Chiller plant sequencer – variable primary flow chiller plant — Setup chillers

With pony chiller selected, provide these additional configuration settings.

Pony Mode EnableAssign a binary reference to allow or prohibit pony chiller operation.


36 BAS-APG037D-EN

Figure 25. Pony Chiller

Pony Chiller Available for Additional CoolingWhen selected, the chiller plant control can add the pony chiller as the last chiller in the sequencewhen additional capacity is needed. Otherwise, the pony chiller is used exclusively as the low-load capacity provider.

Stop Pony Chiller Before Starting Other ChillersWhen selected, chiller plant control will stop the pony chiller before starting the next chiller. Thisconfiguration is used when the flow requirements for each chiller do not favor simultaneousoperation of the pony chiller with another (larger) chiller.

Capacity for Transition to Pony ModeThe transition from the last (larger) chiller to the pony chiller occurs based on the capacity ofeach. Pont chiller operation begins when the capacity of the chiller will be at least the configuredpercentage. At 80%, the transition from the last chiller (assume 400 Tons) to the pony chiller(assume 100 Tons) will occur when the required capacity is 80 Tons (80% of the 100-Ton ponychiller).

Efficiency SettingsSelect from Pure Water, Ethylene Glycol, Propylene Glycol, or other. For pure water, the remaincooling configuration parameters are not used. For Ethylene Glycol and Propylene Glycol,provide the coolant percentage for accurate operation of the application. For all other coolanttypes, select the percentage, specific heat, and specific gravity of that coolant.

Figure 26. Efficiency Settings


BAS-APG037D-EN 37

Cooling Tower Water Return TemperatureProvide the analog reference for the water temperature returning to the cooling tower. Thistemperature is necessary to calculate the fractional lift, required only for efficiency-basedstaging.

Compressor Speed ControlCarefully configured the compressor speed control as either fixed or variable speed, dependingon the capabilities of the actual chiller. This selection is used by chiller plant control to determinethe coefficients pertaining to the efficiency calculations used to determine the staging logic.

CPC Calculates Fractional LiftFor most applications, check the box to allow chiller plant control to calculate fractional lift basedon the current plant conditions compared to the design conditions. Alternately, leave thecalculation check box unchecked, and provide the referenced fractional lift value. Enter thedesign conditions for the condenser and evaporator leaving water temperatures.

Minimum Load LimitFor efficiency-based staging only, chiller plant control will automatically request chillersubtraction when the capacity falls below the minimum load limit, regardless of the plantefficiency.

Maximum Load LimitFor efficiency-based staging only, chiller plant control will automatically request chiller additionwhen the capacity reaches the maximum load limit, regardless of the plant efficiency.

Setup Chillers

Advanced SettingsChiller Lockout

Optionally, provide a binary reference to prevent the chiller from running or being considered inthe chiller plant control sequence.

Auto Reset Failure

When selected, a chiller plant diagnostic will automatically be reset when the correspondingchiller diagnostic has been reset. If left unchecked, each diagnostic must be independently reset.

Verify Running Mode on Chiller Start

Optionally, provide a binary feedback reference to confirm when the (third-party) chiller hasstarted. Normally, the chiller plant control application automatically completes the proper pointreference for Trane chillers.

Primary Chiller Failure Input

As defined by the prior reference the primary chiller failure input status is reported according tothat reference.

Optional Chiller Failure Input

Optionally, provide an additional failure input to confirm chiller start operation. when either theprimary or optional input report a failure, the status will be reported as such.

Unit Power Consumption

Optionally, provide the analog reference to the power consumption (such as kW) of the chiller.When provided, this value will be reported automatically on the chiller dashboard graphic. Thisvalue is not required for efficiency-based staging, only reporting purposes.

Evaporator Water Flow Rate

Optionally, provide the analog reference to the water flow rate (such as GPM) of the chiller. Whenprovided, this value will be reported automatically on the chiller dashboard graphic. This value isnot required for efficiency-based staging, only reporting purposes.


38 BAS-APG037D-EN

AlarmsFailed to Confirm Chilled Water Flow Rate

Optionally, select disable, or provide a binary reference to disable alarming associated with thefailed confirmation of water flow through the chiller. When disabled, all alarms for this purposewill be suppressed.

Failed to Confirm Chiller Running Enable

Optionally, select disable, or provide a binary reference to disable alarming associated with thefailed confirmation of run status of the chiller. When disabled, all alarms for this purpose will besuppressed.

Failed to Confirm Chiller Off Enable

Optionally, select disable, or provide a binary reference to disable alarming associated with thefailed confirmation of off status of the chiller. When disabled, all alarms for this purpose will besuppressed.

Failed to Confirm Chilled Water Flow Off Enable

Optionally, select disable, or provide a binary reference to disable alarming associated with thefailed confirmation of controlling the water flow through the chiller to off. When disabled, allalarms for this purpose will be suppressed.

Figure 27. Setup chiller

Configure Add/Subtract Methods

Add Chiller LogicAdd Delay Time

Once chiller plant control has determined that chiller addition is appropriate, the applicationdelays starting that chiller for this period, during which the conditions required to add the chillermust remain true for the duration.

Reference Point for Adding

Optionally, provide a binary reference to request chiller addition. When true, the binary referenceinitiates the request of a chiller addition, at which point chiller plant control will consider allapplicable timers before starting the chiller. In prior versions, this point was referred to as theAdd Input.


BAS-APG037D-EN 39

Use Temperature Deadband for Adding

When selected, chiller plant control will consider the difference (deadband) between the SystemChilled Water Supply Temperature and System Chilled Water Setpoint to determine when to adda chiller. When the difference exceeds the defined deadband, chiller plant control begins theprocess to add a chiller. When a binary reference is also provided for adding a chiller, chillerplant control will begin the process to add a chiller when either the reference or deadbandcondition is true.

Enable Efficiency-based Add Logic

When selected, chiller plant control will consider efficiency to determine when to request anadditional chiller. For additional information on efficiency-based staging, refer to add andsubtract sections on this document. Efficiency-based add logic can be combined withtemperature deadband (see above) and/or the binary add request (see above) to determine therequest for an additional chiller. If all three are provided/selected, chiller plant control will beginthe process to add a chiller when any of the conditions are true.

Feed Forward Add Signal Time

With the feed forward functionality, the application provides advance notification that a chillerwill be added. Edit this time to provide the desired amount of notice prior to the staging change.Refer to the Details page in Tracer Synchrony for additional information on this function.

Limit Low Load Cycling

When checked, the Low Limit Cycling Delay Time appears and can be edited. When the chiller isthe only running chiller is not in alarm, the chiller may cycle on/off at low loads. Instead ofimmediately proceeding with the add request, chiller plant control delays the request until thecycling delay time expires. This allows ample time for the cycling chiller to maintain the chilledwater supply temperature before initiating an add request.

Subtract Chiller LogicSubtract Delay Time

Once chiller plant control has determined that chiller subtraction is appropriate, the applicationdelays stopping that chiller for this period, during which the conditions required to subtract thechiller must remain true for the duration.

Reference Point for Subtracting

Optionally, provide a binary reference to request chiller subtraction. When true, the binaryreference initiates the request of a chiller subtraction, at which point chiller plant control willconsider all applicable timers before stopping the chiller. In prior versions, this point wasreferred to as the Subtract Input.

Enable Efficiency-based Subtract Logic

When selected, chiller plant control will consider efficiency to determine when to subtract achiller. For additional information on efficiency-based staging, refer to add and subtract sectionson this document. Efficiency-based subtract logic can be combined with the existingtemperature, capacity, and flow logic and/or the binary subtract request (see above) to determinethe request to subtract a chiller. Chiller plant control will begin the process to subtract a chillerwhen any of the conditions are true.

Feed Forward Subtract Signal Time

With the feed forward functionality, the application provides advance notification that a chillerwill be added. Edit this time to provide the desired amount of notice prior to the staging change.Refer to the Details page in Tracer Synchrony for additional information on this function.


40 BAS-APG037D-EN

Figure 28. Chiller Plant Sequencer – Variable Primary Flow Chiller Plant – Configure Add/Subtract Methods

System Setup

SetupChiller Plant Minimum On/Off Time

Edit the duration the chiller plant will remain enabled before it can be disabled. This is also theduration the plant must remain disabled before it can be enabled.

Chiller Start Interval

Edit the amount of time that chiller plant control will suspend all other staging considerationsfollowing the addition of a chiller. This allows ample time for the system to react/stabilize beforeinitiating another step.

System Chilled Water Setpoint

Edit or provide reference to the chilled water setpoint for the system.

Chiller Shutdown Delay Time

Edit the amount of time that chiller plant control will suspend all other staging considerationsfollowing the subtraction of a chiller. This allows ample time for the system to react/stabilizebefore initiating another step.

RotationSelect from the available rotation options. Rotation replaces the identified chiller with the nextchiller (not already running). If selected, rotation can be initiated on a specific day of the week ata specific time, after a fixed number of days at a specific time, or after a specific number of runhours. Alternately, provide reference to a binary point that – when true – requests rotation.

Enable Forced Rotation

When selected, the application will force rotation as soon as one of the conditions specific aboveis true. When left unchecked, the application will rotate chillers when convenient based on add/subtract and other considerations.


BAS-APG037D-EN 41

PumpsSystem Chilled Water Request

Provide the binary reference to request system (secondary) chilled water pump operation. Thispoint is controlled by chiller plant control only when the application is configured to Use ChillerPlant to start up and shut down system chilled water pumps (see first page of setup wizard).

System Chilled Water Flow

Provide the binary reference to the system (secondary) chilled water pump status.

Pump Speed

Provide the analog reference to the chilled water pump speed for each chiller.

Pump Status

Provide the binary reference to the chilled water pump status for each chiller.

SensorsSystem Chilled Water Supply Temperature

Provide the analog reference to the sensor value of the system chilled water supply temperature.This reference is required for all types and configurations.

System Chilled Water Return Temperature

Provide the analog reference to the sensor value of the system chilled water return temperature.This reference is required for all types and configurations.

Figure 29. System setup

InstrumentationFlowMeter

Provide the analog reference to the flow meter of the system. This value is required forefficiency-based staging, and useful for dashboard information for all other system types.

Plant Power Consumption Inputs

To provide accurate data for the chiller plant dashboard and related calculations, select all powerinputs that pertain the to chiller plant, including pumps, tower fans, and supporting equipment.Do not include the chillers in this list, as those are identified separately. Begin by selecting thereference icon, then include all plant power points.


42 BAS-APG037D-EN

Event NotificationsFail chiller plant on system chilled water failures

When selected, provide feedback references for chilled water failures in the Alarms section of thesetup page of the wizard. When left unchecked, no references are required.

Control Feedback Delay Time

Edit the delay time for all feedback tolerance before chiller plant control acts on the failure.

System Failures Class

Select the alarm class for all chiller plant system failures.

Chiller Failures Class

Select the alarm class for all chiller failures.

Figure 30. System setup

Making Chiller Plant Configuration ChangesTo make changes to the chiller plant configuration in the CPC application:

NNoottee:: You must disable the chiller plant and change System Mode to Off before you can changePlant Type or specify new referencers for System Chilled Water Pump Request.

This optional parameter indicates whether or not the CPC application is configured to control achilled water pump using its referencer. If the CPC application is not configured to control asystem pump, this point will not appear on the chiller plant status page or System Chilled WaterFlow (Status).

1. Log in to Tracer Synchrony and navigate to SSyysstteemmss >> CChhiilllleerr PPllaanntt CCoonnttrrooll.

2. Within the Chiller Plant Control section, click the name of the chiller plant.

3. Click ccoonnffiigguurraattiioonn.

4. Make your preferred changes to the available configuration parameters.


BAS-APG037D-EN 43

Sequences of OperationThis sections describes the Chiller Plant Control (CPC) sequences of operation. You may find ituseful to use the sequences to create job submittals or other documents.

NNoottee:: For more detailed sequences of operation including operational flowcharts, see“Troubleshooting Resources,” p. 66.

Chiller Plant SystemModesWhen controlled by the CPC application, a Chiller Plant is in one of the following modes:

• OOffff - The chiller plant is not producing or circulating chilled water.

• NNoorrmmaall - The chiller plant is enabled with at least one chiller running (see “Chiller Plant Start-Up,” p. 43).

• SSoofftt SSttaarrtt - The chiller plant is running, but the normal add chiller logic is not being used (see“Soft Start Mode,” p. 43).

• AAmmbbiieenntt LLoocckkoouutt - The chiller plant is not running because ambient lockout conditions arepresent (see “Ambient Lockout,” p. 45).

• SShhuuttddoowwnn iinn PPrrooggrreessss - The chiller plant is shutting down in an orderly fashion (see theCChhiilllleerr PPllaanntt SShhuuttddoowwnn section in this chapter).

• RRaappiidd PPoowweerr FFaaiilluurree RReeccoovveerryy - The chiller plant is recovering from a power failure (see“Rapid Power Failure Recovery,” p. 45).

• PPoonnyy - The chiller plant is enabled with the pony chiller running.

• PPoonnyy SSoofftt SSttaarrtt - The chiller plant is running with the pony chiller running, but the normaladd logic is not being used (see “Soft Start Mode,” p. 43).

Chiller Plant Start-UpThe startup sequence begins whenever the Chiller Plant Enable value is transitioned fromdisabled to enabled. Typically, there is a point referencer or program on a schedule that is turnedon to enable or disable the chiller plant.

1. Chiller Plant Enable is set to Enabled.

2. The CPC application checks for Soft Start, Rapid Power Failure Recovery, and AmbientLockout requirements:

• If the Soft Start Function is enabled and the System Chilled Water Supply Temperature ishigher than the System Chilled Water Setpoint plus the Soft Start Deadband (Temperature),then System Mode is changed to Soft Start .

• If the Rapid Power Failure Recovery function is enabled and the current Number of ChillersRunning is less than the Number of Chillers Running prior to power failure, then SystemMode is changed to Rapid Power Failure Recovery.

• If the Ambient Lockout Function is enabled and the Outdoor Air Temperature is lower thanthe Ambient Lockout Setpoint, then System Mode is changed to Ambient Lockout .

3. If the CPC application is configured to start up and shut down system chilled water pumps, achilled water request is initiated.

4. The CPC application starts the first chiller in the sequence.

Soft Start ModeSoft Start mode prevents excess capacity from being brought online at startup.

Transitioning into and out of Soft Start ModeAfter a long off period, warm standing water in the chilled water piping will incorrectly indicate ahigh chilled water demand. Using the standard Add logic, the chiller plant will bring capacityonline that exceeds the actual demand.

44 BAS-APG037D-EN

However, if all of the following statements are true, the chiller plant will enter Soft Start mode:

• Enable Soft Start is selected in the chiller plant configuration

• The system requests chilled water from a chiller plant that is enabled, but the System Mode isOff

• The System Chilled Water Return Temperature is higher than the sum of the System ChilledWater Setpoint and the Soft Start Deadband (Temperature)

The following figure shows how the System Mode transitions from Off to Soft Start to Normal asthe System Chilled Water Return Temperature drops. The example uses the following values:

• System Chilled Water Setpoint is 47.5°F (8.6°C)

• Soft Start Deadband (Temperature) is 17.5°F (9.7°C)

Figure 31. Transitioning into and out of soft start mode

Soft Start

System

Chilled W

ater Return Tem

perature

(18.3 °C)65.0°F

System Chilled47.5°F

Water Setpoint(8.6 °C)

Add Temperature Deadband

Soft Start Deadband (Temperature)

45.0°F(7.2 °C)NormalOff

(System Mode)

Add Sequence in Soft Start ModeWhen System Mode is Soft Start, the CPC application adds chillers according to the followingsequence:

NNoottee:: The add logic in Soft Start mode is different from the add logic in normal mode.

1. The CPC application performs a chilled water request.

2. The CPC application continuously monitors the System Chilled Water Return Temperature todetermine whether to add the next stage of cooling capacity:

• FFiirrsstt ssttaaggee:: the first chiller is started in current-limited mode.

• SSeeccoonndd ssttaaggee:: the first chiller is released from current-limited mode.

• TThhiirrdd ssttaaggee:: the second chiller is started in current-limited mode.

• FFoouurrtthh ssttaaggee:: the second chiller is released from current-limited mode.

3. If the temperature is decreasing at a slower rate than the Soft Start Minimum Cooldown Rate(user specified) over the duration of the Add Delay Timer, the next stage of cooling is added.

4. If the System Chilled Water Supply Temperature is decreasing at a faster rate than the SoftStart Minimum Cool down Rate, no additional action is taken.

SSeeqquueenncceess ooff OOppeerraattiioonn

BAS-APG037D-EN 45

NNoottee:: All subtract logic is suspended when the SystemMode is Soft Start.

5. Soft Start mode is deactivated when the System Chilled Water Supply Temperature dropsbelow the System Chilled Water Supply Temperature plus the Add Temperature Deadband.

Rapid Power Failure RecoveryRapid Power Failure is a feature that permits the chiller plant to quickly recover from a loss ofpower to the system controller. It bypasses the Add Delay Timer and Start Interval Timer thatwould otherwise delay the plant from being restored to the capacity it had before power failure.

Checking for Rapid Power Failure RecoveryFor the System Mode to enter Rapid Power Failure Recovery, all of the following conditions mustall be true:

• Enable Rapid Power Failure Recovery must have been selected in the chiller plantconfiguration.

• The chiller plant was running with at least one chiller when the power failed.

• The Number of Chillers Running value is less than the actual number of chillers currentlyrunning.

Rapid Power Failure Recovery OperationIf Rapid Power Failure Recovery is found to be necessary, refer to the following sequence ofoperation:

1. If the CPC application is configured to start up and shut down the system chilled water pump,a chilled water request is performed.

2. The CPC application determines the number (according to its internal count) of chillers thatwere running before the power failure.

3. The CPC application checks with each chiller controller to determine how many of them arecurrently commanded to Auto (run).

4. Compare the number of chillers in Step 3 in the “,”section, to the number of chillers in Step 2.

• If the number of chillers between the two steps matches, no additional action is requiredand the chiller plant System Mode changes to Normal.

• If the number of chillers between the two steps does not match, continue to Step 5 below;this indicates that some of the chillers that were running before the power failure to thesystem controller were stopped when the power failed.

5. Begin commanding chillers On (and their pumps, if controlled by the CPC application) one byone until the required number of running chillers is satisfied, in the following order:

1. Base chiller

2. Normal chillers

3. Peak chiller

NNoottee:: The Add Delay Timer and Start Interval Timer are ignored during Rapid Power FailureRecovery.

Ambient LockoutIf used, Ambient Lockout conserves energy by disabling the chiller plant when the outside airtemperature is less than the specified Ambient Temperature Lockout Setpoint. Ambient Lockoutreleases the chiller plant when the outside air temperature rises above the Ambient TemperatureLockout Setpoint plus the specified Ambient Temperature Lockout Deadband Setpoint. Thealgorithm is illustrated in Figure 32, p. 46 with the following example values:

• Ambient Temperature Lockout Setpoint is 50°F (10°C)

• Ambient Temperature Lockout Deadband Setpoint is 2°F (1.1°C)

• The ambient temperature at which System Mode transitions out of ambient lockout is thesum of the two values above: 50+2=52°F (10 + 1.1 = 11.1°C)


46 BAS-APG037D-EN

Figure 32. Ambient temperature lockout

The following steps describe the basic sequence of operation for the Ambient Lockout feature:

NNoottee:: The Ambient Lockout feature must be selected for the chiller plant and an outsidetemperature reference must be defined.

1. The CPC application monitors the Outdoor Air Temperature.

2. If the Outdoor Air Temperature falls below the Ambient Lockout Setpoint, System Mode ischanged to Ambient Lockout.

3. All chillers and pumps are shut down in an orderly fashion.

4. If the Outdoor Air Temperature rises above the Ambient Lockout Setpoint plus the AmbientTemperature Lockout Deadband Setpoint, System Mode changes to Normal.

System Chilled Water RequestThis section applies if the CPC application is configured to control system chilled water pumps.During initial plant setup, Use Chiller Plant to start up and shut down system chilled water pumpsmust be selected and references to System Chilled Water Pump Request and System ChilledWater Flow Status must be configured.

NNoottee:: For more information about system failure alarms identified in this sequence, see “SystemAlarms,” p. 80.

1. The CPC application commands the System Chilled Water Pump Request On, whichcommands on the system pump.

2. If the command is unsuccessful for the duration of the (Control) Feedback Delay Time, thesystem alarm Failed to Command System Pump On will be active.

3. If there is a referencer set up for System Chilled Water Flow (Status), the system attempts toconfirm flow.

4. If flow cannot be confirmed within the (Control) Feedback Delay Time, the system alarmFailed to Confirm System Chilled Water Flow On will be active.

5. After flow is confirmed, the CPC application can begin the chiller start sequence.

Chiller StagingSelect from two different pre-engineered staging methods – normal (temperature-based) stagingor efficiency-based staging. While normal staging has existed in the product for several years,the efficiency-based alternative was added beginning at v5.6.

Normal (Temperature-based) StagingThe traditional chiller staging method is based on the System Chilled Water Supply Temperatureand System Chilled Water Setpoint. When all applicable timers are satisfied and the system


BAS-APG037D-EN 47

chilled water supply temperature is greater than the setpoint plus Add Temperature Deadband,the application initiates the addition of the next chiller. Subtraction logic considers one of threemethods, namely subtraction based on temperature, chiller/plant capacity, or flow.

Efficiency-based StagingThe efficiency of variable capacity chillers is non-linear and dependent on the load of the chilleras well as system conditions. The maximum efficiency normally occurs at part-load operation,regardless of the conditions. As the efficiency of the chiller begins to decrease, the stagingalgorithm in chiller plant control normally adds/subtracts to optimize the total system efficiency.With the data available to the application, the algorithm considers the current system efficiencyto the would-be efficiency (after addition/subtraction) to determine the ideal point at which theapplication initiates staging. Based on user preference, the application can be configured to alsoconsider the system chilled water supply temperature and setpoint in addition to the efficiency,or allow staging exclusively based on efficiency.

Figure 33. Efficiency-based staging logic

Chiller efficiency is a function of both fractional lift and fractional load. Lift is defined as thepressure differential between the chiller evaporator refrigerant and condenser refrigerant. It canalso be measured as the temperature differential between the leaving chilled water and leavingcondenser water. Water temperature will be used from this point forward for all references to lift.Fractional lift is the operating lift of a chiller divided by its design lift – a value normally between0 and 1. Fractional load is the operating load (Tons) of a chiller divided by its design load – avalue normally between 0 and 1. Efficiency can be measured in several different units, includingkW/Ton, kW/kW, EIR, and COP. The coefficient of performance (COP) is a ratio of kW of coolingprovided to kW input required. Higher COP of a chiller indicates higher efficiency. COP will beused throughout this document when referring to the efficiency.


48 BAS-APG037D-EN

Figure 34. Efficiency lift

Chiller Add1. The CPC application waits for the following conditions to occur:

• The Start Interval Timer must be at 0.

• The Chiller Shutdown Delay Timer must be at 0.

• Add Request Exist must be True. This should happen because the System Chilled WaterSupply Temperature is greater than the sum of the System Chilled Water Setpoint and theAdd Temperature Deadband.

2. The CPC application starts the Add Delay Timer and waits for it to expire.

• If the Add Request Exist does not remain True for the duration of the Add Delay Timer, theAdd Delay Timer is reset and the CPC application goes back to Step 1 of this sequence.

• If the Add Request Exist remains True for the duration of the Add Delay Timer, the CPCapplication begins the Chiller Start sequence for the next chiller to be added.

Add LogicThe logic used to determine when to add a chiller depends upon which mode the chiller plant isin. Chillers can be added when System Mode is Normal or Soft Start.

Normal ModeThe add logic in the CPC application compares the System Chilled Water Supply Temperature tothe System Chilled Water Setpoint plus the Add Temperature Deadband. If the System ChilledWater Supply Temperature exceeds the Chilled Water Setpoint plus the Add TemperatureDeadband, an add request is generated. If desired, you can specify a referencer for Add Input,which will generate an add request any time the referenced value is true. In either case, therequest must exist continuously for the duration of the Add Delay Time before a chiller can beadded. The request logic algorithm is illustrated in “Add Logic,” p. 48 with the followingexample values:

• System Chilled Water Setpoint is 45°F (7.2°C)

• Add Temperature Deadband is 2.5°F (1.4°C)


BAS-APG037D-EN 49

• Add Delay Time is 10 minutes

Figure 35. Add request logic

Add Delay Timer starts

Add Delay Timer resets

System Chilled Water Setpoint

Add Delay Time(10 minutes)

Chiller is added

Add Temperature Deadband 2.5°F (1.4°C)

47.5°F(8.6 °C)

45.0°F(7.2°C)

Soft Start ModeThe add logic in Soft Start mode differs from the one used in Normal mode. In Soft Start mode,the CPC application monitors the System Chilled Water Return Temperature. If this temperatureis not decreasing quickly enough, more cooling capacity is needed. The CPC application monitorshow much the System Chilled Water Return Temperature changes every minute. If the change isnot greater than the Soft Start Minimum Cooldown Rate, the Add Delay Timer begins. The actualcool down rate must be less than the Soft Start Minimum Cooldown Rate for the duration of theAdd Delay Time before the CPC application will issue an add request. The soft start modealgorithm is illustrated in Figure 36, p. 49 with the following example values:

• Soft Start Minimum Cooldown Rate is 0.5°F/min. (0.28°C/min.)

• Start Interval Soft Start Time is 10 minutes

NNoottee:: If both an add request and a subtract request are present, the add request takesprecedence.

Figure 36. Soft start

Add Delay Timer starts

Add Delay Timer stops Chiller is

started

System Return Water Cooling RateStart Interval Soft Start

Time

Soft Start Minimum Cooldown Rate(setpoint)

0.5°F/min.(0.28°C/min.)

Efficiency-based AddWhen configured for efficiency-based staging, the CPC application adds chillers based onmaximum chiller/plant efficiency. Since the maximum efficiency of the chiller occurs at part-loadoperation, the application compares the current overall efficiency of the chiller plant to thewould-be efficiency if the application added a chiller. You can configure the CPC application toexclusively consider efficiency for all staging decisions or select whether temperature shall be an


50 BAS-APG037D-EN

additional consideration, in which case staging shall occur either based on efficiency ortemperature logic. Like the Normal (temperature-based) Mode, you can also specify a referencerfor Reference Point for Adding, which will generate an add request any time the referenced valueis true. In all cases, the request must be true for the duration of the Add Delay Time before theapplication can request an additional chiller.

While the shape and magnitude of the efficiency curves vary based on many factors, thealgorithm in the CPC application calculates the maximum efficiency based on those factors for allchillers/plants/types. Check the box in the setup of the CPC application to also considertemperature for staging logic.


Chiller StartNNoottee:: For more information about chiller alarms identified in this sequence, see “Chiller

Alarms,” p. 81.

1. The CPC application suspends the add and subtract logic.

2. If there is a chiller pump referenced:

a. The pump is commanded on.

b. If the command is unsuccessful within the (Control) Feedback Delay Time, the chilleralarm Failed to command chiller pump on will be active.

c. If there is a referencer set up to confirm flow through the chiller, the CPC applicationattempts to confirm flow.

d. If flow cannot be confirmed within the (Control) Feedback Delay Time, the chiller alarmFailed to confirm chilled water flow will be active.

3. The CPC application commands the chiller on (Auto).

4. If the command is unsuccessful within the (Control) Feedback Delay Time, the chiller alarmFailed to command chiller on will be active.

5. The CPC application initiates the Start Interval Timer. When the timer expires, add andsubtract logic is available.


BAS-APG037D-EN 51

Chiller SubtractNNoottee:: Subtract is invalid when only one chiller is on.

1. CPC application waits the following conditions to occur:

• The Start Interval Timer must be at 0.

• The Chiller Shutdown Delay Timer must be at 0.

• Add Request Exist must be False.

• Subtract Request Exists must be True; this should happen because the subtract logic hasbeen satisfied to its requirements.

2. CPC application starts the Subtract Delay Timer and waits for it to expire.

• If the values of Add Request Exist or Subtract Request Exists change, even momentarily,during the Subtract Delay Time, the Subtract Delay Timer is reset and the CPC applicationgoes back to Step 1.

• If neither the Add Request Exist nor the Subtract Request Exists changes value during theSubtract Delay Time, the CPC application begins the Chiller Stop sequence (see “ChillerStop,” p. 54) for the next chiller to be subtracted.

Subtract LogicTemperature

SSuubbttrraacctt oonn tteemmppeerraattuurree: Whenever the System Delta Temperature is less than the SubtractDelta Temperature, a subtract request is generated. If preferred, you can specify a referencer forSubtract Input, which generates a subtract request any time the referenced value is true. In eithercase, the request must exist continuously for the duration of the Subtract Delay Time before achiller can be subtracted.

• The Subtract Delta Temperature is calculated using the following formulas:

– For sstteeppppeedd flow systems, Subtract Delta Temperature =

DDT x (1 –CTS

) — STDCCE

– For ccoonnssttaanntt flow systems, Subtract Delta Temperature =

DDT x (CCE — CTS)— STD

TCC

Where:

DDT Design Delta Temperature

CTS Cooling Capacity To Subtract

CCE Cooling Capacity Running/Enabled

STD Subtract TemperatureDeadband

TCC Total Cooling Capacity

• The temperature subtract algorithm is illustrated in the following figure with example values:

– Subtract Delta Temperature is 6.2°F (3.4°C)

– Design Delta Temperature is 10°F (5.5°C)

– Subtract Delay Time is 20 minutes


52 BAS-APG037D-EN

Figure 38. Chiller subtract based on temperature

Subtract Delay Timer starts

System Chilled Water Delta Temperature

Design Delta Temperature

Subtract Delta Temperature

Subtract Delay Time

Chiller is subtracted

10°F (5.5°C)

Subtract Delay Timer reset

6.2°F (3.4°C)

0°F (0°C)

CapacitySSuubbttrraacctt oonn ccaappaacciittyy: The CPC application calculates the capacity of the running chillers, andthen compares it to the capacity after the next chiller were to be subtracted. When the EstimatedPlant Capacity After Subtraction ≤ Subtract RLA Setpoint subtract request is generated. Ifpreferred , you can specify a referencer for Subtract Input, which will generate a subtract requestany time the referenced value is true. In either case, the request must exist continuously for theduration of the Subtract Delay Time before a chiller can be subtracted.

Estimated Plant Capacity After Subtraction is the estimated average load of the remainingchillers after the next chiller is subtracted. It is calculated as illustrated in the following figure.

Figure 39. Formula for estimated plant capacity after subtraction

Chiller 4(OFF)

Chiller 3(ON)

Chiller 2(ON)

Chiller 1(ON)

CCE is Cooling Capacity Enabled—the sum of the

design capacity of all running chillers

CTS is Cooling Capacity To Subtract—the design capacity of just the next chiller to be subtracted

=Estimated Plant

Capacity After Subtraction

RLA (for each chiller) is the current run load amps of a chiller expressed as a percentage of the chiller’s maximum allowable amperage. If you are using a non-Trane chiller, make sure that the RLA can be reported as a value between 0 and 100 or you will not be able to use the Subtract on Capacity method.CDC (for each chiller) is the chiller design capacity.

((RLA/100) x CDC) + ((RLA/100) x CDC) + ((RLA/100) x CDC) + ((RLA/100) x CDC) + ...

CCE - CTS


BAS-APG037D-EN 53

Figure 40. Chiller subtract based on capacity

Estimated Plant Capacity After Subtraction

SubtractTimer starts

SubtractTimer resets

Chiller is subtracted

Desired Average Capacity After SubtractionSubtract Delay Time

(20 minutes)

FlowSSuubbttrraacctt oonn ffllooww: Based on the measured flow through the bypass pipe. If the flow in the excessdirection exceeds the flow capacity of the chiller to be subtracted (plus a deadband), a subtractrequest is generated. If preferred, you can specify a referencer for Subtract Input, which willgenerate a subtract request any time the referenced value is true. In either case, the request mustexist continuously for the duration of the Subtract Delay Time before a chiller can be subtracted.

• The Flow Required to Subtract is calculated using the following equation:

– Flow Required to Subtract =

FTS x (1 +SEF

)100

FTS Flow to Subtract

SEF Subtract Excess Flow Percent

The following figure shows a subtract request based on flow.

Figure 41. Chiller Subtract based on Flow

Chiller is subtractedFlow Required to Subtract

Subtract Timer starts

Subtract Timer resets

Subtract Delay Time

1080 gpm (62 L/s)


54 BAS-APG037D-EN

Efficiency-based SubtractWhen configured for efficiency-based staging, the CPC application subtracts chillers based onmaximum chiller/plant efficiency. Since the maximum efficiency of the chiller occurs at part-loadoperation, the application compares the current overall efficiency of the chiller plant to thewould-be efficiency if the application subtracted a chiller. You can configure the CPC applicationto exclusively consider efficiency for all staging decisions or select whether temperature shall bean additional consideration, in which case staging shall occur either based on efficiency ortemperature logic. Like the Normal (temperature-based) Mode, you can also specify a referencerfor Reference Point for Subtracting, which will generate a subtract request any time thereferenced value is true. In all cases, the request must be true for the duration of the SubtractDelay Time before the application can request chiller subtraction.

While the shape and magnitude of the efficiency curves vary based on many factors, thealgorithm in the CPC application calculates the maximum efficiency based on those factors for allchillers/plants/types. Check the box in the setup of the CPC application to also considertemperature for staging logic.


Chiller StopNNoottee:: For more information about chiller alarms identified in this sequence, see “Chiller

Alarms,” p. 81.

1. The CPC application suspends the add and subtract logic.

2. The CPC application commands the chiller to Off.

3. If the command is unsuccessful within the (Control) Feedback Delay Time, the chiller alarmFailed to command chiller off will be enabled.

4. If there is a referenced chiller pump, the chiller pump is commanded Off.

5. If the command is unsuccessful within the (Control) Feedback Delay Time, the chiller alarmFailed to command chiller pump off will be enabled.

6. The CPC application waits for flow Off verification. If flow is not confirmed Off within the(Control) Feedback Delay Time, the chiller alarm Failed to confirm chiller chilled water flowoff will be enabled.


BAS-APG037D-EN 55

Chiller Plant ShutdownNNoottee:: For more information about failure alarms identified in this sequence, see “System

Alarms,” p. 80 or “Chiller Alarms,” p. 81.

1. Chiller Plant Enable is set to Disabled.

2. The CPC application performs the Chiller Stop sequence for each enabled chiller in thereverse of the startup order.

3. The CPC application verifies chiller communication status is up. If communication is lost, theSystemMode remains at Shutdown in Progress and waits for communication to be restored.

4. The CPC application checks to make sure all of the chillers are off. If all chillers are not offwithin the (Control) Feedback Delay Time, the chiller alarm Failed to confirm chiller off willpost, and System Mode remains at Shutdown in Progress.

5. If the CPC application is configured to control the system chilled water pump, the SystemChilled Water Request is commanded Off. If the command is unsuccessful within the(Control) Feedback Delay Time, the system alarm Failed to Command System Pump Off willbe enabled, and SystemMode remains at Shutdown in Progress.

6. The CPC application waits for system flow off verification. If flow is not confirmed off withinthe (Control) Feedback Delay Time, the system alarm Failed to Confirm System Chilled WaterFlow Off will be enabled, and System Mode remains at Shutdown in Progress.

7. If no system alarms are present upon completion of the sequence, System Mode is changedto Off.

Chiller Setpoint CalculationsThis section describes how the CPC application calculates the System Chilled Water Setpointbased on Plant Type and chiller arrangement.

Constant FlowThe CPC application calculates a different Chilled Water Setpoint for each chiller based on thefollowing equation:

• Chilled Water Setpoint =

SSP— (RWT x (1 — (CCE/TCC)))

(CCE/TCC)

SSP System Chilled Water Setpoint

RWT System Chilled Water Return Temperature

CCE Cooling Capacity Enabled

TCC Total Cooling Capacity Running

Stepped Flow, Variable Primary Flow, and Decoupled LoopFor Stepped Flow, Variable Primary Flow, and Decoupled Loop, each chiller’s Chilled WaterSetpoint is the same as the System Chilled Water Setpoint.

SeriesIf a Plant Type is Series, the CPC application calculates and sends a unique Chilled WaterSetpoint to each of the chillers based upon the System Chilled Water Setpoint, the position of thechiller (which is indicated by the series index number) to each chiller. The calculation for eachrunning chiller is shown here:


56 BAS-APG037D-EN

Figure 43. Series chilled water setpoints

1CCE

–CDC---------------1-

Chilled Water RWT – SSP + SSP

Chiller Index 1Setpoint for =

1CCE

–CDC1--------------------------------------

+CDC2- RWT –SSP + SSP

Chilled Water

Chiller Index 2=Setpoint for

1CCE

–CDC1-------------------------------

CDC2+ +------------------------------

CDC3- RWT –SSP + SSPChilled Water

Chiller Index 3=Setpoint for

( )( ) ( )

( ( )) ( )

( ( )) ( )

Where:

CDC Chiller design capacity

CCE Cooling Capacity Enabled

RWT System Chilled Water Return Temperature

SSP System Chilled Water Setpoint

NNoottee:: The calculation is only performed for the chillers that are running; the chiller designcapacity for non-running chillers is subsequently not added into the equation.

Unload at Start• Before the CPC application adds an additional chiller, it can unload any operating chillers.

Older chiller controllers often had difficulties responding to the flow discontinuities caused bystarting additional chillers. Unloading the running chillers helped to alleviate this problem.Variable primary flow systems may also benefit from unloading the chillers because of theflow fluctuations that can occur with this type of piping system.

• The mechanism for unloading at start is to current limit the actively running chiller or chillers.One minute before adding a chiller, the CPC application unloads all chillers designated tounload at start. These chillers remain unloaded until the chiller being enabled is proven to beOn.

Chiller RotationChillers are sequenced so that the last chiller enabled is the first to be disabled. Rotating thechiller sequence occurs manually or at operator-defined intervals.

Rotations can occur at one of the following operator-defined intervals:

• NNeevveerr - Chillers will always have the same sequence numbers.

• DDaayy ooff tthhee WWeeeekk - Chillers will rotate on a user-specified day and time once per week.

• FFiixxeedd NNuummbbeerr ooff DDaayyss - Chillers will rotate after the number of days specified has elapsed.

• RRuunn HHoouurrss - Chillers rotate to attempt to even out the amount of time each chiller runs. Whenany chiller reaches the user-defined run hours setpoint (which is measured only from the lastrotation), the CPC application can re-sequence the chillers, if necessary, to put the chiller withthe least total run hours into a higher-use position in the sequence.

• RRoottaattiioonnaall IInnppuutt - Chillers rotate when the specified reference commands them to rotate.

NNoottee:: When the System Mode is Enabled, at least one chiller is running.

An operator entry determines whether the chillers are immediately enabled or disabled tocomply with the new sequence after a rotation occurs. If forced rotation is disabled, the CPC


BAS-APG037D-EN 57

application waits for normal variations in the system load to adjust the sequence of chillers. Ifforced rotation is enabled, the chillers are forced to comply with the new sequence immediately.

There are four sequence types for chillers:

• Base chillers

• Peak chillers

• Swing chillers

• Pony chillers

All other chillers are considered “Normal” chillers, and they follow a scheduled rotationalsequence. Only one chiller of each special type is allowed by the CPC application. However, allthree special types can exist in the same chiller plant.

Base ChillerThe base chiller is always the first chiller on and the last chiller off (For example, if the chillerplant is enabled, the base chiller is enabled).

Peak ChillerThe peak chiller is always the last chiller enabled and the first chiller to be disabled. Often, thepeak chiller is an older or less efficient chiller that should run only if absolutely necessary.

Swing ChillerA swing chiller is 1/3 to 2/3 the size of the other chillers in the plant. It is the first chiller (if no baseexists) to be enabled and then alternates (enabled/disabled) with the remaining chillers in theplant. The purpose of a swing chiller system is to more closely match the cooling capacitygenerated by the chiller plant to the cooling load.

Pony ChillerA pony chiller is used at night or low-load conditions in lieu of applying the other chillers in theplant. The pony chiller is normally smaller than the others and sized to handle the low loadconditions. The pony chiller can also be configured to be added as the last chiller in the sequencewhen additional capacity is needed.

Chiller Plant Control SequencingThe table below shows the order in which the CPC application would sequence a plant with allthree special types and two normal chillers. See also “Order of Events in Adding and SubtractingChillers,” p. 82.

Table 3. Steps of capacity in a typical chiller plant

Step Chiller 1(Base)

Chiller 3(Swing) Chiller 4 (#1) Chiller 5 (#2) Chiller 2

(Peak)

1 ON OFF OFF OFF OFF

2 ON ON OFF OFF OFF

3 ON OFF ON OFF OFF

4 ON ON ON OFF OFF

5 ON OFF ON ON OFF

6 ON ON ON ON OFF

7 ON ON ON ON ON


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Pony Example 1Pony Chiller Mode Command FALSE

Pony Available for Additional Cooling FALSE

Low Load Load 1 Load 2 Load 3 Load 4

Peak Chiller

Chiller 2

Chiller 1

Pony Chiller

Pony Example 2Pony Chiller Mode Command TRUE

Pony Available for Additional Cooling FALSE


Peak Chiller

Chiller 2

Chiller 1

Pony Chiller

Pony Example 3Pony Chiller Mode Command FALSE

Pony Available for Additional Cooling TRUE


Peak Chiller

Chiller 2

Chiller 1

Pony Chiller

Pony Example 4Pony Chiller Mode Command TRUE

Pony Available for Additional Cooling TRUE


Peak Chiller

Chiller 2

Chiller 1

Pony Chiller

Chiller Available/UnavailableThere are four available modes for a chiller:

• AAvvaaiillaabbllee - available by the user and Lockout is False; this is the only mode in which the CPCapplication can try to control the chiller.

• UUnnaavvaaiillaabbllee - unavailable by the user and Lockout is False.

• LLoocckkoouutt - available by user and Lockout is True.

• UUnnaavvaaiillaabbllee//LLoocckkoouutt - unavailable by the user and the Lockout is True.

This feature allows an operator to take a chiller out of the sequence by selecting a button on astatus screen. For example, if maintenance is required for a chiller, this feature can be used totemporarily remove the chiller from the sequence. This prevents CPC application from trying toenable the chiller and marking it as failed during the time it is down for maintenance. After the


BAS-APG037D-EN 59

maintenance is completed, the chiller is made available again by selecting a button on the statusscreen.

A chiller can also be made unavailable (locked out) by referencing another point in the system.For example, a heat exchanger can be controlled as a chiller by the CPC application and it wouldbe available to provide cooling capacity when conditions allow it. It would be locked out whenconditions are not suitable. (For a heat exchanger to be used as a chiller, it must be installed as achiller object in Tracer SC+.)


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Special ApplicationsNo two chiller plants are alike, and all chiller plants require at least some customized orspecialized control considerations. Essentially all specialization relies upon using customprograms. Tracer SC+ uses the second generation Tracer Graphics Programming (TGP2)language to accommodate special applications.

Where to find TGP2 ProgramsTGP2 programs, including programs for chiller plant control, are available in the PPSConfigurator.

Enabling a Chiller PlantEnabling the chiller plant allows the plant to begin the sequence that will determine theappropriate system mode and ultimately start the chiller plant if conditions meet therequirements for startup. Possible methods to turn on a chiller plant:

• MMaannuuaall oovveerrrriiddee - A user can turn the chiller plan on and leave it on indefinitely. Thismethod is not preferred because it is energy inefficient and/or requires constant operatorintervention.

• PPllaaccee tthhee cchhiilllleerr ppllaanntt iinn aa sscchheedduullee -The schedule can be made according to knownbuilding operation hours. This method is not preferred because 1) it requires a lot of operatorintervention (change of schedules); 2) It is virtually impossible to run the chiller plant outsideof the schedule, for instance if a tenant initiates a timed override from a thermostat, or if thearea needs to go into a night cooling mode, it cannot do so.

• CCoonnttrrooll tthhee cchhiilllleerr ppllaanntt wwiitthh tthhee TTrriimm//RReessppoonndd aapppplliiccaattiioonn iinn TTrraacceerr SSCC++ - Use the Trim/Respond application in Tracer SC+/Synchrony to enable chiller plant operation. From withinthe setup of the application, select/edit the predefined condition by which the applicationenables and disable chiller plant operation.

Figure 44. Enable chiller plant with Trim/Respond application

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Variable Primary Flow SystemsVariable primary flow systems require some additional custom programming to manage lowflow conditions in a chiller, which are not managed by the CPC application. Low flow conditionsat a chiller occur as the following sequence of events occurs:

• Cooling demand decreases.

• Chilled water valves on the cooling coils begin to close.

• Differential pressure across the load increases.

• Primary pump speed decreases to maintain the differential pressure setpoint.

• Chilled water flow through the chiller decreases.

If the flow rate is allowed to drop below the minimum design flow rate of the chiller while thechiller is running, the chiller could be severely damaged.

To prevent the flow rate reduction below the point where damage is caused, the bypass valve isopened to allow some of the supply water to bypass the load and go back through the systempump and the chiller(s). The pressure differential measured across the load drops as a result ofthe supply water bypassing the load, and the system pump speeds up to maintain the differentialpressure setpoint, which results in a higher flow rate through the chiller(s).

EExxaammpplleeThe following figure illustrates a variable primary flow chiller plant in which the low demand hascaused the chilled water valves on the load to start modulating closed, such that the differentialpressure across the entire load has increased, causing the chilled water pump to slow down tomaintain the system chilled water differential pressure setpoint. As a result, the flow through therunning chiller, has dropped to 480 gpm (30.3 l/sec.).The minimum flow setpoint for the chiller is500 gpm (31.6 l/sec.); therefore in this scenario, the flow rate must be increased by 20 gpm toprevent potential damage to the chiller.

Figure 45. Variable primary low flow scenario Part 1 — Initial condition

SSppeecciiaall AApppplliiccaattiioonnss

62 BAS-APG037D-EN

Figure 46, p. 62 shows how the chiller plant overcomes the low flow condition. A TGP2 programis required to monitor the chilled water flow through the chillers (the flow rate is calculated fromthe differential pressure across the chillers). When a low flow condition is detected, the programwill begin to modulate the bypass valve open, which permits chilled water to bypass the load.This diverted flow causes a drop in the differential pressure across the load. As a result thechilled water pump must speed up to maintain the system differential pressure setpoint.

The end result is that the flow rate through the chiller is sufficient to satisfy the chiller minimumflow setpoint. In this case, the initial 480 gpm (30.3 l/sec.) flow rate was increased by 20 gpm (1.3l/sec) to achieve the minimum 500 gpm (31.6 l/sec.) flow rate through the chiller. Likewise, as theload increases, the differential pressure across the load will decrease, which causes the pump tospeed up and increase the flow through the chillers. When the flow through the chillers begins toexceed the minimum flow setpoint of the chiller, the bypass valve begins to modulate closed.

Figure 46. Variable primary low flow scenario Part 2 — Resolution

Calculating flow across a chillerThe flow rate across a chiller (q1) can be calculated using a DP flow meter. The followinginformation about the chiller can be found in the job submittal:

• Design pressure (Delta P)(dp2)

• Design flow rate (q2)

With the above information, measure the flow rate (dp1), and then enter into the followingequation:

The following figure shows what the equation looks like as a TGP2 program.


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Figure 47. TGP2 program for calculating flow across a chiller

The equation above can be implemented using a formula block in TGP2 as shown in Figure 48, p.63.

Figure 48. TGP2 formula block with flow expression

How to Control the Bypass ValveWWiitthh oonnee cchhiilllleerr

The basic logic for opening the bypass valve in a variable primary flow chiller plant with a singlechiller is as follows:

The programmable controller continuously monitors the flow rate across the chiller. As long asthe flow rate is greater than the chiller minimum flow rate requirement, the programmablecontroller sends an analog value of 0 to the bypass valve, and the valve stays closed.

If the flow rate drops below the chiller minimum flow rate requirement, the programmablecontroller performs a PID calculation and sends a value to the bypass valve to open it to thecalculated percentage. As the bypass valve opens, the differential pressure across the load drops,which causes the system pump to speed up. The program in the following figure incorporatesthe flow rate calculations in the above sequence to control the bypass valve.

Figure 49. TGP2 program for controlling the bypass valve


64 BAS-APG037D-EN

WWiitthh mmoorree tthhaann oonnee cchhiilllleerr

Figure 50, p. 64 shows the basic logic for opening the bypass valve when there is more than onechiller in the variable primary flow chiller plant. It is similar to the logic for a single chiller.

Figure 50. TGP2 program for monitoring multiple chillers and controlling the bypass valve

Writing TGP2 Programs Across Multiple Tracer SC+ ControllersIn systems with multiple Tracer SC+ system controllers, it may be necessary to gather largequantities of data from several individual system controllers and use the data in the systemcontroller in which the chiller plant is configured. Examples include chilled water requests andmaximum valve position data used to determine when to enable a chiller plant.

It may be intuitive to pass data from each point directly to the system controller with the chillerplant. However this approach would be more labor intensive and possibly more complicatedthan it need be. Figure 51, p. 65 shows how chilled water requests can be passed from SC+ 1 andSC+ 2 to SC+ 3 without passing all of the data between controllers.


BAS-APG037D-EN 65

Figure 51. Example programming TGP2 with multiple Tracer SC+ system controllers


66 BAS-APG037D-EN

Troubleshooting ResourcesThis section provides general information that may help troubleshoot problems that you mayencounter while setting up or operating the CPC application.

Sequence of Operations Flow ChartsThe following charts provide detailed information about the logical flow of each operationhandled by the Tracer SC+ CPC application. The flow charts are designed with two different usesin mind.

• FFoorr ggeenneerraall iinnffoorrmmaattiioonnaall ppuurrppoosseess: Review each flowchart, starting with “SystemOverview,” p. 66, and use it as a logical hub to see how all of the sub-modules areinterconnected. The flowcharts are potentially more detailed and informative than thesequences of operation, and provide a graphical view of the processes that some users mayfind easier to follow.

• FFoorr ttrroouubblleesshhoooottiinngg: End-users who are more experienced can go directly to the individualsub-modules and compare the flowchart to the actual behavior of the system.

System OverviewThe System Overview flow chart provides an overview of the entire process that the CPCapplication follows every time it runs (once per minute). Decision points are not shown in thisflowchart and can be assumed based upon the process conditions at any given time. Return tothis flowchart after each module if you are new to CPC, and then use it to determine where to gonext.

BAS-APG037D-EN 67

Figure 52. System overview flowchart

Chiller Plant EnableTypically a TGP2 program tells the CPC application to enable the chiller plant, which begins thesequence to determine what system mode the chiller plant will be in and implements the startupactions, if needed. This flowchart describes how this module determines which system mode thechiller plant should be in after it has been enabled.

TTrroouubblleesshhoooottiinngg RReessoouurrcceess

68 BAS-APG037D-EN

Figure 53. Chiller plant enable

Soft StartThe Checking for Soft Start flowchart illustrates how the CPC application determines whether thesystem settings and conditions are appropriate to change the System Mode to Soft Start.Possible outcomes of this sequence are to require Soft Start mode or not require Soft Startmode. See also “Soft Start Mode,” p. 43.


BAS-APG037D-EN 69

Figure 54. Checking for soft start

Rapid Power Failure RecoveryThe Checking for Rapid Power Failure Recovery flowchart, shown below, describes how the CPCapplication checks whether to set System Mode to Rapid Power Failure Recovery. The followingflowchart illustrates how Rapid Power Failure Recovery starts chillers when required. See also“Rapid Power Failure Recovery,” p. 45.


70 BAS-APG037D-EN

Figure 55. Checking for rapid power failure recovery


BAS-APG037D-EN 71

Figure 56. Rapid power failure recovery mode

Ambient LockoutThe Checking for ambient lockout flowchart shown below illustrates how the CPC applicationdetermines whether to change System Mode to Ambient Lockout. See also “AmbientLockout,” p. 45.


72 BAS-APG037D-EN

Figure 57. Checking for ambient lockout

System Pump StartThe System pump start flowchart shown below illustrates how the CPC application determineswhether it controls and monitors the system pump, how it starts the pump, and how it mightrespond to any system pump alarms that may occur during startup. See also “System ChilledWater Request,” p. 46.


BAS-APG037D-EN 73

Figure 58. System pump start

Add ChillerThe Add chiller flowchart illustrates how the CPC application continuously applies the add logicto the current chiller plant status and determines when the next chiller will be started. Possibleoutcomes of this sequence are for the chiller plant to start the next chiller or not start the chiller,and continue to run the logic. See also “Add Logic,” p. 48.


74 BAS-APG037D-EN

Figure 59. Add chiller

Chiller StartThe Chiller start sequence flowchart show below illustrates how the CPC application starts thechiller chilled water pump (if applicable) and the chiller, and how it responds to any alarms thatmay occur during the chiller start sequence. See also “Chiller Add,” p. 48.


BAS-APG037D-EN 75

Figure 60. Chiller start sequence

Subtract ChillerThe Subtract Chiller flow chart, shown below, illustrates how the CPC application continuouslyapplies the appropriate subtract logic to the current chiller plant status and determines when tosubtract the next chiller. Possible outcomes of this sequence are for the chiller plant to subtractthe next chiller or not subtract the chiller, and continue to run the logic. See also “SubtractLogic,” p. 51.


76 BAS-APG037D-EN

Figure 61. Subtract chiller

Chiller StopThe Chiller stop sequence flowchart, shown below, illustrates how the CPC application stops thechiller chilled water pump (if applicable) and the chiller and how it responds to any alarms thatmay occur during the chiller stop sequence. See also “Chiller Stop,” p. 54.


BAS-APG037D-EN 77

Figure 62. Chiller stop sequence


78 BAS-APG037D-EN

System DisableThe System Disable flowchart, shown below, illustrates how the CPC application shuts down theentire chiller plant. See also “Chiller Plant Shutdown,” p. 55.

Figure 63. System disable

System Pump StopThe System pump stop sequence flowchart, shown below, illustrates how the CPC applicationstops the system chilled water pump and how it responds to any alarms that may occur duringthe system pump stop sequence. See also “Chiller Plant Shutdown,” p. 55.


BAS-APG037D-EN 79

Figure 64. System pump stop sequence


80 BAS-APG037D-EN

System AlarmsThe following table lists all of the system failure alarms that can be generated by the CPCapplication and how the application will operate as a consequence when they occur. Failures thatinvolve chilled water flow have two different possible responses depending upon the value ofSystem Chilled Water Request Failures Enabled.

NNoottee:: Control failures (such as "Failed to control...") will occur when the Tracer SC+ cannot writethe command to the configured point, typically due to a loss of communication.Confirmation failures (such as "Failed to confirm...") will occur if the control has beensuccessfully issued, but the returned status does not match the expected result.

Table 4. Chiller Plant control responses to system alarms

Failure Message OccursWhenValue of System ChilledWater Request

Failures Enabled

Enabled Disabled

Failed to CommandSystem Pump On

CPC application wasunable to command thereferenced point for theduration of the (Control)Feedback Delay Time

• Retry the command

• Do not start thechillers

• Suspend the logic tocheck for flow

• Clear the alarm whencommand successfulor plant disabled

• Retry command

• Continue startsequence

• Suspend logic tocheck for flow

Failed to Confirm SystemChilled Water Flow On

CPC application wasunable to confirm flow onfor the duration of the

(Control) Feedback DelayTime

• Do not start chillers

• Continue to monitorflow

• Clear when flow isproven and plant willcontinue startsequence

• Continue startsequence

• Clear when flow isproven

Failed to CommandSystem Pump Off


• Continue to try to turn off until the plant is enabled

• Suspend logic to check for flow off

• Clear when command successful

Failed to Confirm SystemChilled Water Flow Off

CPC application wasunable to confirm flow offfor the duration of the

(Control) Feedback DelayTime

• Notify only

• Clear alarm when flow is proven off

System Chilled WaterFlow Lost

CPC application detected aloss of flow for the

duration of the (Control)Feedback Delay Time

• Turn off all chillers

• Leave system pumpon

• Continue to monitorflow

• Clear when flow isproven then startadding chillers

• Continue operation asnormal

• Clear when flow isproven

System Chilled WaterSupply Sensor Failure

Any time the SystemChilled Water SupplyTemperature is not

updated within 15 minutesor when the value is out ofrange, this failure occurs

• Suspend temperature based add and subtract logicand soft start function

• Clear the alarm when the System Chilled WaterSupply Temperature is updated with a valid value


BAS-APG037D-EN 81

Table 4. Chiller Plant control responses to system alarms (continued)

Failure Message OccursWhenValue of System ChilledWater Request

Failures Enabled

Enabled Disabled

System Chilled WaterReturn Sensor Failure

Any time the SystemChilled Water ReturnTemperature is notupdated within 15

minutes, or when thevalue is out of range, this

failure occurs

• Suspend temperature based subtract logic and softstart function

• Clear the alarm when the System Chilled WaterReturn Temperature is updated with a valid value

Failed to Read BypassFlow

Any time the System(Chilled Water) BypassFlow is not updated within15 minutes, or when thevalue is out of range, this

failure occurs

• Suspend flow based subtract logic

• Clear the alarm when the System (Chilled Water)Bypass Flow is updated with a valid value

All Chillers Have FailedThis failure will occur anytime all available chillers

are failed

• System chilled water request remains on

• Clear when at least one chiller is not failed

All Chillers are UnavailableThis message will occurany time all chillers are

unavailable

• System chilled water request remains on

• Clear when at least one chiller is available and is notfailed

Chiller AlarmsThe following table lists all of the chiller failure alarms that can be generated in the CPCapplication and how the application will operate as a consequence when they occur. Somecommands have two different possible responses depending upon the value of Auto ResetFailure setting.

Table 5. CPC application responses to chiller alarms

Failure Message OccursWhen...Value of Auto Reset Failure

Disabled1 Enabled

Failed to command chillerpump on


• Fail Chiller/Pump pair • Retry command aslong as the CPCapplication requeststhe chiller

• Continue the chillerstart sequence

• Clear when the chilleris requested off orwhen the command issuccessful

Failed to confirm chilledwater flow

CPC application wasunable to confirm flow

through the chiller for theduration of the (Control)Feedback Delay Time

• Fail Chiller/Pump pair • Continue chiller startsequence

• Clear when the chilleris requested off orwhen flow exists


1. Requires a manual reset on the chiller plant control Status page.

82 BAS-APG037D-EN

Table 5. CPC application responses to chiller alarms (continued)

Failure Message OccursWhen...Value of Auto Reset Failure

Disabled2 Enabled

Failed to command chilleron

CPC application wasunable to command thechiller member on for theduration of the (Control)Feedback Delay Time

• Fair Chiller/Pump pair • Retry command aslong as CPCapplication requeststhe chiller

• Continue the startsequence

• Clear when the chilleris requested off orwhen the command issuccessful

Failed to confirm chillerrunning

CPC application wasunable to confirm chillerrunning mode start afterenabling the chiller for theduration of the (Control)Feedback Delay Time

• Fail Chiller/Pump pair

• Check to see ifanother chiller can bestarted without delay

• Clear when the plantis disabled or thechiller starts

Failed to command chilleroff

CPC application wasunable to command thechiller member off for theduration of the (Control)Feedback Delay Time

• Fail Chiller/Pump pair • Continue to issue stopcommand untilrequested on again

Failed to confirm chiller off

CPC application wasunable to confirm a

compressor start afterenabling the chiller for theduration of the (Control)Feedback Delay Time

• Fail Chiller/Pump pair • Continue normaloperation; clear whenit goes off orcommanded to runagain

Failed to command chillerpump off


• Fail Chiller/Pump pair • Retry command aslong as chiller is off

• Clears when chiller isturned on

Failed to confirm chiller-chilled water flow off

CPC application wasunable to confirm flow offthrough the chiller for theduration of the (Control)Feedback Delay Time

• Continue normal operation

• Clear if the chiller is commanded on

Chiller Manual ResetActive

This alarm will appear anytime the chiller diagnosticshutdown property is

active

• Fail Chiller/Pump pair • Fail Chiller/Pump pair

• Clears whendiagnostic shutdownis inactive

Optional chiller failureinput active

This alarm will appear anytime the optional failureinput reference is true

• Fail Chiller/Pump pair • Fail chiller/pump pair;clear when inputclears

Comm LostThis alarm will appear anytime Tracer SC+ detects aloss in communication

• Fail Chiller/Pump pair

• Clear when communication is restored

Order of Events in Adding and Subtracting ChillersThe charts in Figure 65, p. 83 detail the sequence of events that would occur when a chiller plant(with up to five chillers, base, swing, normal 1, normal 2, and peak) is subjected to a continuousadd request from the time it is enabled until it is fully loaded.

Figure 66, p. 84 shows the same chiller plant that begins as fully loaded, and then subjected to acontinuous subtract request until it is disabled.


2. Requires a manual reset on the chiller plant control Status page.

BAS-APG037D-EN 83

NNoottee:: The charts cannot be adapted to any number of chillers in the plant, but the principles ofthe add and subtract sequences can be applied in general regardless of the size of theplant.

Figure 65. Detailed chiller add sequence for up to five chillers


84 BAS-APG037D-EN

Figure 66. Detailed chiller subtract sequence for up to five chillers


BAS-APG037D-EN 85

Appendix: Communicating Information BetweenMultiple SCs

Systems with chiller plants are typically large enough to have multiple system controllers. As aresult, it may be necessary to use a TGP2 program to pass information between SC+s. Someexamples are:

• Chilled water requests

• Maximum Valve positions

• Occupancy status of a piece of equipment

There are two general methods to pass information: push or pull:

• PPuusshh - With this method, SC+ 1 sends information as often as configured and SC+ 2 waits forthe information to be sent.

– Because SC+ 2 does not initiate the transmission of information, it uses the heartbeattimer to determine when or if the information has taken too long to be sent before thepoint on SC+ 2 enters the fault state.

– Recommended practice is to generate a fault after SC+ 2 does not receive the thirdconsecutive transmission: For example, set up the SC+ 1 to send the data every twominutes and set the heartbeat timer on SC+ 2 to six minutes.

– This method is slower to respond to a fault condition but may be preferable because it isless likely to trigger an unnecessary fault.

• PPuullll - With this method, SC+ 2 pulls the value from SC+ 1 at every update interval.

– Because SC+ 2 initiates the exchange of information, a fault is generated at the firstopportunity for an update.

– It is a potentially faster way to generate a fault and thus would be used in cases where arapid response is required.

Sharing Data Between Two Tracer SC+sTo set up communication between Tracer SC+ controllers, it is necessary to create points in eachcontroller. The following procedures describe both the “Pull” and “Push” methods, using achiller plant scenario.

Sharing Data Using the Pull MethodUse the following procedure to set up a reference for a chilled water request from SC+ 1, whichdoes not have the chiller plant in it, to SC+ 2, which does have the chiller plant. The assumptionis that SC+ 1 and SC+ 2 are already properly configured to communicate with each other.

1. Create a binary value point in SC+ 1 that indicates the chilled water request. The value wouldtypically be controlled by a TGP2 program.

2. At the Tracer Synchrony user interface, click DDeevviicceess from the left navigation menu. TheDDeevviicceess page opens.

3. Click on the AApppplliiccaattiioonn SSCC tab. Locate and record the device ID; save for a later step. (Seethe following figure.)

86 BAS-APG037D-EN

Figure 67. Locate the device ID

4. Navigate to the DDeettaaiillss tab of the point that you created in step 1, and locate the instancenumber (see the following figure). Record the instance number for a later step.

Figure 68. Point details page (locating the instance number)

5. End you session with Tracer SC+ 1.

6. Log in to Tracer SC+ 2.

7. Click PPooiinnttss from the left-navigation menu.

8. On the PPooiinnttss page, click Create Point. Create a binary input point in SC+ 2 and name it “SC+1Chilled Water Request” or a similar meaningful name.

9. Click SSeelleecctt eexxtteerrnnaall BBAACCnneett rreeffeerreennccee..

10. Enter the device ID, point type, and instance number that you recorded in an earlier step (seethe following figure). Select VVaalluuee from the property drop-down list.

11. Click AAppppllyy to return to the CCrreeaattee PPooiinntt page.

12. Set the update interval for the binary input point. The interval should be how often you wantSC+2 to request the chilled water request status.

• An interval of 1 to 5 minutes is recommended for BACnet IP data sharing.• An interval of 5 to 15 minutes is recommended for BACnet MS/TP data sharing.

AAppppeennddiixx:: CCoommmmuunniiccaattiinngg IInnffoorrmmaattiioonn BBeettwweeeenn MMuullttiippllee SSCCss

BAS-APG037D-EN 87

13. Enter any other preferred point data, then click SSaavvee.

The chilled water request from SC+ 1 is now available to be used in SC+ 2 as needed.

Figure 69. Setting up an external reference

Sharing Data Using the Push MethodThe following example of a "push" method is a chilled water request. SC+ 1 is the controller thatreceives the request from some device connected to it. SC+ 2 is the controller that must receivethe request to start its chiller plant.

By using this method, the output point can be configured to send the data at a rate that is fasterthan the heartbeat interval on the receiving value object. This allows for multiple attempts to bemade at sending the data before the value point enters a fault state.

1. At the Tracer Synchrony user interface, click PPooiinnttss from the left navigation menu. ThePPooiinnttss page opens.

2. Click the CCrreeaattee PPooiinntt button, then select BBiinnaarryy VVaalluuee.

3. Enter the following information in the fields as shown in the following figure.

• Name – Chilled water request (user specified)– Heartbeat – enable (to detect communication failures)– Heartbeat Interval – 15 minutes (recommended range is 30 seconds to 12 hours)

NNoottee:: The point will enter a fault state if not written to within the heartbeat interval.This value should be a multiple of the update interval of the point in the sourcedevice.

4. Enter preferred data in the remaining fields.

5. Click SSaavvee.


88 BAS-APG037D-EN

Figure 70. Configuring a Binary Value point

6. Obtain the SC+ 2 Device ID and point instance number of the binary value you create aboveas described in “Sharing Data Using the Pull Method.” Save for a later step.

7. End your session with SC+ 2, and log in to Tracer SC+ 1.

8. Create a binary output point.

a. From the PPooiinnttss page, click CCrreeaattee PPooiinntt, and select BBiinnaarryy OOuuttppuutt.

b. Click the reference icon. The SSeelleecctt DDaattaa SSoouurrccee dialog box opens.

c. Select EExxtteerrnnaall BBAACCnneett RReeffeerreennccee.

d. Enter the SC+ 2 Device ID and point instance number that you recorded in an earlier step.Select Value from the property drop-down list.

e. Click AAppppllyy to return to the CCrreeaattee PPooiinntt page.

f. Enter any other preferred data, then click SSaavvee.


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Glossary

The following terms apply specifically to chiller plant control and the Chiller Plant Control (CPC)application with Tracer SC+. In some cases there is more than one name with the same meaningon different screens in the user interface. The differences are indicated by (parentheses) and/or aslashes "/" in terms.

AAActive Chiller AlarmsIndicates any chiller plant alarms present for the individual chillers. It does not specify the exact nature of the alarm.

Active Chiller Plant System AlarmsIndicates system-level alarms within the CPC application, such as system sensors or system pump failures.

Add Chiller LogicThe parameters used to determine when to add a chiller to the chiller plant, including the Add Delay Time, AddTemperature Deadband, and Chiller Start Interval. You can also specify an Add Input referencer.

Active Cool/Heat Setpoint TemperatureTypically indicates the Chilled Water Setpoint or the Evaporator Leaving Water Temperature Setpoint for a chiller,but in cases of chillers that support heating, this value could indicate the hot water setpoint.

Add Delay TimeThe length of time that an add chiller request must be present before chiller plant control will enable the next chiller.The add request must be present continuously for the entire Add Delay Time.

Add Delay TimerThe point indicates the amount of time remaining before a chiller will be added. It is active whenever Add RequestExist is active. An additional chiller will not be added until this timer expires.

Add InputThe name of an optional user-specified referencer (a binary output from a TGP2 program) that is used to initiate anadd request.

Add Request ExistA binary input that Indicates whether there is a current request to add a chiller in the CPC application. The point isprimarily used as a status indicator in graphics, TGP,or third-party integrators.

Add TemperatureThe sum of the System Chilled Water Setpoint and the Add Temperature Deadband.

Add Temperature DeadbandIndicates by howmany degrees the System Chilled Water Supply Temperaturemust exceed the System ChilledWater Setpoint before an add request is generated.

All Chillers are UnavailableAn informational-only system warning that is True whenever all chillers in the chiller plant are either unavailable orlocked out.

All Chillers Have FailedA system alarm that indicates that all chillers in the chiller plant are failed.

Ambient Temperature Lockout Status/ActiveIndicates whether ambient lockout is currently locking out the chiller plant. When the value is Lockout or Active, theSystem Mode should be Ambient Lockout. No chillers or system pumps can be activated, even if the system isenabled.

Ambient Temperature Lockout Deadband SetpointThe user-defined number of degrees above the Ambient Temperature Lockout Setpoint that the temperature mustreach before the ambient lockout function will be disabled.

Ambient Temperature Lockout Function(ality)Indicates whether Enable Ambient Temperature Lockout has been selected on the chiller plant configuration page.

Ambient Temperature Lockout SensorThe current temperature reading on the ambient lockout sensor. This is the value used to initiate and end theambient lockout function and is typically Outdoor Air Temperature.

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Ambient Temperature Lockout SetpointThe user-defined temperature below which ambient temperature lockout function will be enabled.

Auto Reset FailureIf selected, permits the CPC application to reset some chiller failures if certain conditions are met. See “ChillerAlarms,” p. 81.

BBase ChillerAlways the first chiller to start and the last chiller to stop. Unless the base chiller cannot be run, it will always runwhen the chiller plant is enabled.

CChilledWater SetpointThe temperature of water that an individual chiller is trying to reach at the temperature sensor at or near its outlet.

Chiller Being Added or SubtractedIndicates the index number of the chiller that is actively being added or subtracted. If the value is 0, there are nochillers being added or subtracted.

Chiller Index NumberThe number assigned to the chiller when the chiller is added to the chiller plant. It is a unique identifier that is usedto reference chiller plant member list data. An index number can only be assigned once for any given chiller plant.(For instance if an index number is assigned to a chiller and the chiller is removed, and then added again, it will get anumber that has never been assigned to another chiller.)

Chiller Shutdown Delay TimeThe user-defined amount of time provided to permit a newly started chiller to come up to setpoint before apreviously running chiller is shut down. This delay is only used on a two-step add or subtract process involving aswing chiller, or during forced rotation. See “Order of Events in Adding and Subtracting Chillers,” p. 82.

Chiller Shutdown DelayTimerIf a value is present, it indicates howmuch time remains before a previously running chiller will be shutdown.

Chiller Start IntervalThe length of time that must pass after a chiller is started before the CPC application can activate the add or subtractlogic. This interval allows the flow rate and temperatures in the chiller plant to stabilize.

Chillers Running Out of SequenceIndicates if the chillers in the chiller plant are running in a different sequence than currently configured. Thisproperty is typically True after a rotation occurs and Enable Forced Rotation is not selected.

Chiller Failure ExistsIndicates whether the CPC application is unable to properly control a chiller. The point is primarily used as a statusindicator in graphics, TGP2, or third-party integrators.

Chiller Failure ResetA point that allows chiller failures that are within the CPC application to be reset by an external source. The point isprimarily used in graphics, TGP, or third-party integrators.

Chiller Failure(s)/(Alarm Notification) ClassThe event notification class that will be used to for routing chiller alarms in the CPC application.

Chiller Manual Reset ActiveThis alarm will appear any time the chiller diagnostic shutdown property is active.

Chiller Plant EnableThe value (Enabled or Disabled) of this point determines whether the chiller plant is allowed to run. This point can bemanually operated, but it is typically referenced to a TGP2 program that determines when to enable or disable thechiller plant (See “Enabling a Chiller Plant,” p. 60).

ChilledWater Supply TemperatureSee System Chilled Water Supply Temperature.

Comm LostThis alarm will appear any timeTracer Synchrony detects a loss in communication.

Constant FlowOne of four user-selectable plant types. (See “Constant Flow,” p. 14).

(Control) Feedback Delay TimeThe amount of time the CPC application waits for system pumps, chiller pumps, the chiller compressor, or chilledwater flow status to proven before generating a system or chiller alarm.

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(Control) Feedback Delay TimerHowmuch time remains of the (Control) Feedback Delay Time before an alarm is generated.

Cooling Capacity Running/EnabledThe sum of the cooling capacities of each chiller that is currently running.

Cooling Capacity To SubtractIndicates the cooling capacity of the chiller that is next in line to be subtracted.

Current OperationA multi-state input that indicates the current status of the CPC application. The point is primarily used in graphics,TGP, or third-party integrators.

CW setpointSee Chilled Water Setpoint.

CW tempThe actual chilled water supply temperature for a chiller as read by a temperature sensor downstream from thechiller. This is the same as the Evaporator Leaving Water Temperature.

DDecoupled System (Primary-Secondary)One of four user-selectable plant types. (See “Primary and secondary loops,” p. 17).

DescriptionThe user-assigned description of the chiller plant. This field appears on the chiller Configuration page.

Design Delta TemperatureThis value should be the actual design ΔTof the chillers in the system. It is the difference between the entering andleaving chilled water temperatures that the chillers can achieve when they are fully loaded.

EEfficiency-based StagingWhen configured for efficiency-based staging, the CPC application adds chillers based on maximum chiller/plantefficiency. Since the maximum efficiency of the chiller occurs at part-load operation, the application compares thecurrent overall efficiency of the chiller plant to the would-be efficiency if the application added a chiller.

Enable Forced RotationA check box that can be selected when a chiller plant is created or edited. If it is selected, the chillers willimmediately conform to the new sequence when changed. If not selected, the new sequence will take effect basedon loading or when the chiller plant is shut down.

Enable Ambient Temperature LockoutA check box that can be selected when a chiller plant is created or edited. If it is selected, the ambient lockoutfeature will be used for the chiller plant. See “Ambient Lockout,” p. 45.

Enable Rapid Power Failure RecoveryA check box that can be selected when a chiller plant is created or edited. If it is selected, the rapid power failurerecovery feature will be enabled for the chiller plant. See “Rapid Power Failure Recovery,” p. 45.

Enable Soft StartA check box that can be selected when a chiller plant is created or edited. If is selected, the soft start feature will beused for the chiller plant. See “Soft Start Mode,” p. 43.

Estimated Plant Capacity After SubtractionIndicates howmuch cooling capacity will be left after the next chiller to be subtracted is subtracted from the plant.

Excess Flow PercentageSpecifies howmuch excess flow must still remain even after the next chiller is subtracted, as a percentage of thecapacity of the chiller to be subtracted. This ensures that a small increase in demand after chiller subtraction will notcause an add request.

FFacility Outdoor Air TemperatureAn analog input that is automatically created by Tracer Synchrony. It can be configured on the Installation/OutdoorAir Conditions page.

Fail Chiller on AlarmAn option that, if selected, will fail the chiller if any alarm conditions occur.

Fail chiller plant on system chilled water failuresAn option that, if selected, will fail the entire chiller plant if a system failure is detected. Examples include systempump failure to confirm “on” or System Chilled Water Supply Sensor Failure active.

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Failed to command chiller offCPC application was unable to command the chiller member off for the duration of the Feedback Delay Time.

Failed to command chiller onCPC application was unable to command the chiller member on for the duration of the Feedback Delay Time.

Failed to command chiller pump offCPC application was unable to command the referenced point for the duration of the Feedback Delay Time.

Failed to command chiller pump onCPC application was unable to command the referenced point for the duration of the Feedback Delay Time.

Failed to Command System Pump OffIndicates that the CPC application attempted to command the system pump off, but the command was unable to besent. This failure cannot occur if the System Chilled Water Pump Reference is not referenced by the CPC application.The failure typically occurs when the referenced controller is offline.

Failed to Command System Pump OnIndicates that the CPC application attempted to command the system pump on, but the command was unable to besent. This failure cannot occur if the System Chilled Water Pump Reference is not referenced by the CPC application.The failure typically occurs when the referenced controller is offline.

Failed to confirm chilled water flowCPC application was unable to confirm flow through the chiller for the duration of the Feedback Delay Time.

Failed to confirm chiller chilled water flow offCPC application was unable to confirm flow off through the chiller for the duration of the Feedback Delay Time.

Failed to confirm chiller offCPC application was unable to confirm a chiller turned off after commanding it off for the chiller for the duration ofthe Feedback Delay Time.

Failed to confirm chiller runningCPC application was unable to confirm chiller running mode start after enabling the chiller for the duration of theFeedback Delay Time.

Failed to Confirm System ChilledWater Flow OffA system alarm that indicates that the CPC application attempted to confirm that the flow is stopped, but was unableto confirm that flow actually did stop. This failure cannot occur if the System Chilled Water Flow (Status) is notreferenced by the CPC application.

Failed to Confirm System ChilledWater Flow OnA system alarm that indicates that the CPC application attempted to confirm system flow, but was unable to confirmthat flow actually did start. This failure cannot occur if the System Chilled Water Flow (Status) is not.

Failed to Read Bypass FlowA system alarm that indicates that the CPC application attempted to read the bypass flow, but was unable to get areading. Can only appear on system type Decoupled System (Primary-Secondary).

Feedback DelayTimeSee (Control) Feedback Delay Time.

Flow Required to SubtractThe determining factor for subtracting a chiller on Decoupled System (Primary-Secondary) plants with flow subtractmethod. The value is the sum of the design flow of the next chiller to be subtracted and the Excess Flow Percentage.

Forced Rotation EnabledSee Enable Forced Rotation.

IIndex Number of Chiller to be AddedThe index number of the chiller that will be added after the Add Delay Timer expires.

Index Number of Chiller to be SubtractedThe index number of the chiller that will be subtracted after the Subtract Delay Timer expires.

LLast Rotation TimeIndicates the date and time of the most recent chiller rotation.

MMinimum Cooldown RateSee Soft Start Minimum Cooldown Rate.

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NNameThe user-assigned name of the chiller plant. This field is editable on the chiller Configuration page when the SystemMode is Off.

Name of Chiller to be AddedIndicates the name of the next chiller that will be added.

Name of Chiller to be SubtractedIndicates the name of the next chiller that will be subtracted.

Next Rotation TimeIndicates when the next chiller rotation will occur, if the rotation setting is Day of week or Fixed number of days.

Number of Chillers RunningIndicates the number of chillers that are currently running.

OOperating StatusIndicates the actual active activity that is occurring within the CPC application. The following table represents thevalues that can be seen in TGP2 when referencing the property:

Description Value

Disabled 1

Disabling 2

Dispatch 3

Turning SystemWater Request On 4

Waiting for System Chilled Water Flow 5

Unload 6

Turning Chiller Pump On 7

Waiting for Chiller Chilled Water Flow On 8

Turning Chiller On 9

Verifying Chiller On 10

Turning Chiller Off 11

Verifying Chiller Off 12

Turning Chiller Pump Off 13

Turning SystemWater Request Off 14

Verifying System Chilled Water Flow Off 15

Optional chiller failure input activeThis alarm will appear any time the optional failure input reference is true.

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PPlant TypeOne of four possible values: constant flow, stepped flow, variable primary flow, or decoupled loop. (See “ChillerPlant Types,” p. 12). The following values can be seen in TGP2 when referencing the Plant Type value. The numberof types increases to account for different subtract methods:

Description Value

Constant Flow -Water always flows through all chillers (Subtract on Temperature) 1

Constant Flow -Water always flows through all chillers (Subtract on Capacity) 2

Stepped Flow -Water flows though running chillers only (Subtract on Temperature) 3

Stepped Flow -Water flows though running chillers only (Subtract on Capacity) 4

Decoupled System (Primary-Secondary) - Water flows through running chillers only(Subtract on Temperature) 5

Decoupled System (Primary-Secondary) - Water flows through running chillers only(Subtract on Flow) 6

Decoupled System (Primary-Secondary) - Water flows through running chillers only(Subtract on Capacity) 7

Variable Primary Flow - Variable water flows through chillers 8

Pony ChillerA pony chiller is used at night or low-load conditions in lieu of applying the other chillers in the plant. The pony chilleris normally smaller than the others and sized to handle the low load conditions. The pony chiller can also beconfigured to be added as the last chiller in the sequence when additional capacity is needed.

Power Failure Recovery FunctionIndicates whether or not Supports Rapid Power Failure Recovery is selected on the configuration page.

Primary Chiller Failure InputThis is the reference Chiller Plant Control will use to determine failures in a chiller. When a failure occurs, CPC will failthe chiller and take it out of the sequence. By default, CPC will reference the "Diagnostic Shutdown Present" of TraneChillers.

RRapid Power Failure RecoveryA feature within the CPC application to quickly return the chiller plant to the operating status it was in before powerfailed. It bypasses delay periods that would otherwise be enforced during normal operation.

Request PendingRequest Pending Indicates whether there is an add request, subtract request, or no changes required:

Description Value

None 1

Add 2

Subtract 3

RLARun load amps.

Rotation InputIf a referencer is used to initiate chiller rotation, it allows an external referencer, such as a TGP2 program or agraphic to initiate the rotation. The plant will only initiate a rotation on a change of value from False to True.

Rotation TimeIndicates the time of day that the next rotation will occur, if the rotation setting is Day of week or Fixed number ofdays.

SSeries Chiller PlantIndicates whether the CPC application has been configured for a series chiller plant. This property will determinewhether or not the series chilled water setpoint calculation is used to calculate the individual setpoints for eachchiller.

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Series Index NumberIn a series chiller plant, the user-specified number that indicates the actual physical position of the chiller. lower-numbered chillers are ahead of, or upstream from the higher-numbered chillers.

SetpointSee Ambient Temperature Lockout Setpoint, Add Temperature Deadband, Minimum Cooldown Rate Setpoint,Subtract Flow Setpoint, Subtract RLA Setpoint, System Chilled Water Setpoint, and System ΔT Setpoint.

Soft Start Deadband (Temperature)The number of degrees that is added to the System Chilled Water Setpoint to indicate when it is necessary to use thesoft start feature. See “Soft Start Mode,” p. 43.

Soft Start FunctionA feature within the CPC application to prevent excess capacity from being brought online when the chiller plant isenabled and the system chilled water supply temperature is not near its setpoint.

Soft Start Minimum Cooldown RateThe minimum rate at which the System Chilled Water Return Temperaturemust drop to prevent the system fromadding another chiller during soft start mode.

Start Interval Normal TimeThe amount of time the CPC application must wait before looking to see if there is an add or subtract request.

Start Interval Soft Start TimeThe amount of time the CPC application must wait before starting a chiller during a soft start.

Start Interval TimerHowmuch of the Start Interval Normal Time or the Start Interval Soft Start Time remains, whichever reflects thecurrent mode.

Stepped FlowOne of four user-selectable plant types. (See “Stepped Flow,” p. 16.)

Subtract Chiller LogicThe equations used to determine when to subtract a chiller from the chiller plant. The equations depend upon theSubtract Method, and includes some combination of Design Delta Temperature, Subtract Temperature Deadband,Subtract Delay Time, System (Chilled Water) Bypass Flow, Excess Flow Percentage, (Chiller) Running Capacity, andEstimated Plant Capacity After Subtraction. You can also specify a Subtract Input referencer.

Subtract Delay TimeThe length of time that a subtract chiller request must be present before the CPC application will subtract the nextchiller. The subtract request must be present continuously for the entire Subtract Delay Time.

Subtract Delay TimerThe point indicates the amount of time remaining before a chiller will be subtracted. It is active whenever SubtractRequest Exists is active. A chiller will not be added until this timer expires.

Subtract Delta TemperatureWhen Subtract Method is Subtract on Temperature, this calculated value determines when a chiller can besubtracted. It applies to the temperature difference between the System Chilled Water Return Temperature and theSystem Chilled Water Supply Temperature.

Subtract Excess Flow PercentSee Excess Flow Percentage.

Subtract Flow SetpointWhen Plant Type is Decoupled System (Primary-Secondary) and Subtract Method is Subtract on Flow, thiscalculated value determines when a chiller can be subtracted. It represents the sum of the design flow of the chillerto be subtracted and its Excess Flow Percentage.

Subtract InputThe name of an optional user-specified referencer (a binary output from a TGP2 program) that is used to initiate asubtract request.

Subtract MethodOne of three possible ways that the CPC application can use to determine when to subtract a chiller: Temperature,Capacity, or Flow. Not all methods are available for all plant types. (See “Chiller Subtract,” p. 51.)

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Subtract RLA SetpointWhen Subtract Method is Subtract on Capacity, this setpoint value determines when a chiller can be subtracted.When the Estimated Plant Capacity After Subtraction is less than the Subtract RLA Setpoint, a subtract request willbe generated.

Subtract Request ExistsA binary input that Indicates whether there is a current request to subtract a chiller in the CPC application. The pointis primarily used as a status indicator in graphics, TGP, or third-party integrators.

Subtract Temperature DeadbandThis user-defined value is used in the calculation of the Subtract Delta Temperature. It prevents an immediate addrequest from occurring after a subtraction.

Supports Rapid Power Failure RecoveryA user-selected option that indicates whether the chiller plant should be used with the Rapid Power Failure Recoveryfunction after a power failure.

System (ChilledWater) Bypass FlowA measurement of the excess flow going through the bypass pipe on Decoupled System (Primary-Secondary) planttypes, which indicates unneeded capacity in the chiller plant.

System ChilledWater Delta TemperatureIndicates the current difference between the System Chilled Water Return Temperature and the System ChilledWater Supply Temperature.

System ChilledWater Flow (Status)The value of this point indicates whether or not the system flow is detected. It is an optionally referenced property.

System ChilledWater Flow LostAn alarm that indicates that the system failed to confirm flow when the CPC application attempted to start a systempump. This alarm can only occur if a system pump and a system flow sensor are referenced.

System ChilledWater Flow SensorA point that represents the system chilled water flow. It will only be used if System Chilled Water Flow Sensor Existsis True.

System ChilledWater Flow Sensor ExistsThis optional parameter indicates whether or not the CPC application is configured with a chilled water flow sensor.

System ChilledWater Pump RequestThis optional parameter indicates whether or not the CPC application is configured to control a chilled water pumpusing its referencer. If the CPC application is not configured to control a system pump, this point will not appear onthe chiller plant status page.

System ChilledWater Request Failures EnabledIndicates how the CPC application responds to system failures. If enabled, the CPC application will fail the entirechiller plant on a system failure. If it is disabled, the CPC application will attempt to continue to run all unaffectedportions of the chiller plant, based upon the nature of the nature of the failure(s).

System ChilledWater Return Sensor FailureIndicates whether or not the system chilled water return sensor is currently failed or not.

System ChilledWater Return TemperatureThe temperature reading of the water that is returning from the building load to the chillers.

System ChilledWater SetpointThe net temperature of water that the chiller plant is trying to reach at a temperature sensor on a common chilledwater pipe downstream from all of the chillers. This value is not always the same as the Chilled Water Setpoint for anindividual chiller.

System ChilledWater Supply Sensor FailureIndicates whether or not the system chilled water return sensor is currently failed or not.

System ChilledWater Supply TemperatureThe temperature reading of the water that is being supplied by the chiller plant to the building load.

System Failures ClassThe event notification class that will be used to for routing system alarms in the CPC application.

SystemModeName of a point on the chiller plant status page, under status. Values can be Normal, Ambient Lockout, Soft Start,Rapid Power Failure Recovery, Shutdown in Progress, or Off.

System ReturnWater Cooling RateThe rate at which the return water temperature is decreasing in degrees per minute.

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TTotal Cooling CapacityThe sum of the cooling capacities of all of the chillers in the chiller plant.

UUse Chiller Plant to start up and shut down system chilled water pumpsA check box on the Create/Edit Chiller Plant page that permits you to use the CPC application to control the systemchilled water pump(s). If it is not selected, the option will not be available when creating a chiller plant.

VVerify Running Mode on Chiller StartEnabled by default, this option is available for each chiller member and will dictate whether CPC will verifycompressor status when starting a chiller or not. This option can be enabled/disabled or referenced to another pointin the system. A good use of this feature is when chillers need to run in low load situations to move water but do notneed to chill the loop.

WWhenWill a Chiller Be Added?Indicates the conditions that must be present before a chiller is added.

WhenWill A Chiller Be Subtracted?Indicates the conditions that must be present before a chiller is subtracted.

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Trane - by Trane Technologies (NYSE: TT), a global innovator - creates comfortable, energy efficientindoor environments for commercial and residential applications. For more information, please visittrane.com or tranetechnologies.com.

Trane has a policy of continuous product and product data improvements and reserves the right to change design and specifications withoutnotice. We are committed to using environmentally conscious print practices.

BAS-APG037D-EN 20 Aug 2021

Supersedes BAS-APG037C-EN (May 2020) ©2021 Trane

Chiller Plant Control

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