08.08.26-VariableAirHVACPresentation
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Transcript of 08.08.26-VariableAirHVACPresentation
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 1Version: 9/00
VAV SystemsJeff Wotnosky
Trane Sales Engineer
Raleigh, North Carolina
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 2Version: 9/00
VAV systems
Agenda
• What is Variable Air Volume (VAV)• Why(/Not) design VAV systems • What buildings utilize VAV• VAV system types and their components
• Changeover Bypass ( Varitrac)• True VAV ( Varitrane)• Single Zone VAV
• System control considerations• Leed and VAV• Questions?
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 3Version: 9/00
What is Variable Air Volume(VAV)What is Variable Air Volume(VAV) ? ?
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 4Version: 9/00
VAV SystemAir handler/Packaged UnitAir handler/Packaged Unit
buildingbuildingautomationautomationsystem (BAS)system (BAS)
VAVVAVterminalterminal
unitsunits
supplysupplyductworkductwork
returnreturnductworkductwork
supply-airsupply-airdiffusersdiffusers
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 5Version: 9/00
Characterstics of VAV systemsCharacterstics of VAV systems
Constant air temperature off AC UnitConstant air temperature off AC Unit
Vary the air volume as load requiresVary the air volume as load requires
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 6Version: 9/00
Why use VAV?
• Provides multiple zones of comfort
• Life cycle cost will be less than other HVAC Systems trying to accomplish similar comfort levels
• Load diversity• Smaller equipment ( lower AC unit first cost compared to
Constant Volume)• Less supply air ( less energy consumption)
• Able to adapt to changes in building use
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 7Version: 9/00
Why Not ??
• Higher first cost than comparable single zone • Controls, equipment, commissioning
• Increased maintenance cost• More pieces to look after• Terminal units might be located in occupied space
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 8Version: 9/00
Common places to use VAV systemsCommon places to use VAV systems
Commercial/Medical Office buildingsCommercial/Medical Office buildingsSchools ( all levels)Schools ( all levels)Houses of worshipHouses of worshipConference CentersConference Centers
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 9Version: 9/00
VAV System TypesVAV System Types
Changeover Bypass (Varitrac)Changeover Bypass (Varitrac)
“True VAV” (Varitrane)“True VAV” (Varitrane) Single Zone VAV Single Zone VAV
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VariTrac Changeover / Bypass System
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• Cost Effective way to zone Standard packaged Rooftop units or Split Systems
• Often Driven by Light Commercial contractors:• Used to “Package Rooftop Equipment”• Desire somewhat simple installations and want to get on
and off the job quickly.• Want to get a little more flexibility than their typical
applications
What is VariTrac?
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 12Version: 9/00
Changeover/Bypass VAV System Layout
EA
OA
RA
Constant volumeConstant volumeSupply fanSupply fan
VariTracVariTracdamperdamper
PA
bypass damperbypass damper
VAV to spaceVAV to spaceSA
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 13Version: 9/00
Where would you use VariTrac?• Ideal candidates for VariTrac Systems
are:• one-story office buildings, clinics, movie
theaters, strip malls, light manufacturing centers.
• Examples are offices within a church, school, or manufacturing facility seeking individual (zoned) temperature control.
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Light Commerical RTU
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Light Commercial Split System
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VariTrac Changeover Bypass System
Main unit options:-Voyager or Precedent RTU (ReliaTel)-Odyssey Split System (ReliaTel)-Existing Non-DDC w/opt. relay board (CCP)
VaiTrac or VariTraneUnits with reheat
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 17Version: 9/00
• Cooling only standard• Trane Controller
• Factory-installed, downloaded, and tested controller
• Remote reheat control• Round or Rectangular• Airside
• Pressure Dependent System (damper position control- no direct CFM measurement)
• Up to 1.75” system pressure
VariTrac Dampers
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 18Version: 9/00
Central Control Panel
• “Self-Configuring”• High Quality Installation• Repeatable Performance
• Up to 24 Zones• Optional touch screen user interface• PC-Free Setup for basic functions• Simple PC interface with Windows™ based
software• Interfaces with Main AHU via 2H/2C Control• Scheduling
• 2 Start/Stop Times• Schedule 4 Groups of Zones
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How is changeover achieved?
• Voting• CCP polls UCM’s
• On a minimum calls for changeover the CCP will disable heat or cool and enable heat or cool
• CCP then communicates to UCM’s new control mode and UCM’s control to different setpoints
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 20Version: 9/00
True VAV System – (Varitrane)Air handler/Packaged UnitAir handler/Packaged Unit
buildingbuildingautomationautomationsystem (BAS)system (BAS)
VAVVAVterminalterminal
unitsunits
supplysupplyductworkductwork
returnreturnductworkductwork
supply-airsupply-airdiffusersdiffusers
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 21Version: 9/00
True Variable-Air-Volume SystemTrue Variable-Air-Volume System
EA
OA
RA
variable-variable-speed drivespeed drive
supplysupplyfanfan
coolingcoolingcoilcoil
thermostatthermostat
VAVVAVboxbox
PA
SA
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 22Version: 9/00
VAV Terminal UnitsVAV Terminal Units
Fan-poweredFan-poweredVAV terminal unitVAV terminal unit
Dual-ductDual-ductVAV terminal unitVAV terminal unit
Single-duct, cooling-Single-duct, cooling-onlyonlyVAV terminal unitVAV terminal unit
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 23Version: 9/00
VCCFVCCF
• Single duct• Cooling only• No auxiliary heat
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VCCFVCCF
primaryprimaryairair
supplysupplyairair
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VCWFVCWF
• Single Duct w/hot water reheat• Hot Water Coils
• 1 & 2 row coils• Built in access panel for
cleaning
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VCWFVCWF
primaryprimaryairair
supplysupplyairair
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VCEFVCEF
• Single duct w/electric reheat• 8 different voltages• Up to 3 stages of heat• Interlocking door
disconnect• Heater line fuse• Magnetic or mercury
contactors• Element removal
through control enclosure
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 28Version: 9/00
Terminal Reheat SystemTerminal Reheat System
EA
PA
OA
RA
supplysupplyfanfan
coolingcoolingcoilcoil
reheatreheatcoilcoil
thermostatthermostat
SA
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 29Version: 9/00
parallel,parallel,fan-powered VAV fan-powered VAV terminal unitterminal unit
Fan-Powered VAVFan-Powered VAV
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Parallel, Fan-Powered Parallel, Fan-Powered
primary primary airair
supplysupplyairair
terminal terminal mixing fanmixing fan
plenumplenumairair
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Parallel Fan-Powered VAV
cool primary airfrom rooftop unit
warm air recirculatedfrom ceiling plenum(first stage of heat)
heating coil(second stage of heat)
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supplysupplyairair
terminal terminal mixing fanmixing fan
plenumplenumairair
Series, Fan-PoweredSeries, Fan-Powered
(Electrically Commutated Motors – ECM’s )(Electrically Commutated Motors – ECM’s )
primary primary airair
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 33Version: 9/00
Parallel vs. SeriesParallel vs. Series
• Intermittent fan• Fan only runs in the
heat mode (Variable Volume to the space)
• Fan is the first stage of heat
• Fan CFM < Max Cooling• Most energy efficient
design• Sound in space will vary
• Continuous fan• Fan runs continuously
in the occupied mode (constant volume to the space)
• Fan CFM = Max Cooling• Less energy efficient
system design• Smaller main supply
fan?• ECM Motors• Sound remains same
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 34Version: 9/00
fan-powered VAV
Series Versus Parallel
MinneapolisLos AngelesAtlanta40
60
80
100
120
140
HV
AC
en
erg
y c
on
su
mp
tion
,%
of
base
parallel FPVAVVAV reheat series FPVAV with ECM
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 35Version: 9/00
Fan Powered Units: Cooling Fan Powered Units: Cooling OnlyOnly
• Plenum Air provides “free” reheat from lights, etc.• Parallel units (only
when fan energized)• Series (increases as air
valve closes)
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 36Version: 9/00
Fan Powered Units: Cooling Fan Powered Units: Cooling with Hot Water Reheatwith Hot Water Reheat
• Model VPWF/LPWF (Parallel)• Reheat coil mounted on plenum
inlet (optional discharge)
• Model VSWF, LSWF (Series)• Reheat coil mounted on
discharge
• Coil Offerings• 1 Row• 2 Row
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Fan Powered Units: Cooling Fan Powered Units: Cooling with Electric Reheatwith Electric Reheat
• Model VPEF / LPEF(Parallel)• Discharge mounted• UL listed
• Model VSEF/ LSEF (Series)• Discharge mounted• UL listed
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 38Version: 9/00
Fan Powered Units: Electric Fan Powered Units: Electric Heater OptionsHeater Options
• 8 different voltages• 2 stages of heat (plus the
fan as stage 1)• Interlocking door
disconnect• Heater line fuse• Air flow switch• Magnetic or mercury
contactors
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 39Version: 9/00
Differences between VariTrac and VariTrane
• VariTrac• Used in Smaller buildings seeking cost-effective zone control• Simpler System Control• Less expensive than VariTrane• Smaller Constant Volume AHU/RTU (Typically 15 tons or less)• Up to 24 zones• Pressure Dependent
• VariTrane • Used in Larger Buildings seeking ideal occupant comfort• Very Flexible System Control (more complex sequences)• Larger Variable Volume AHU/RTU equipment (up to 130 Tons)• Up to 120+ zones• 30% fan energy savings over CV• Pressure Independent
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VAV System TypesVAV System Types
Single Zone VAV Single Zone VAV
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Single Zone VAVSingle Zone VAV
AHU is your VAV Box !! AHU is your VAV Box !!
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Application for Single Zone VAVApplication for Single Zone VAV
Large areas Large areas ( conference rooms, assembly halls…)( conference rooms, assembly halls…)
Control air flow off room sensor Control air flow off room sensor
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 43Version: 9/00
ControlsControls
Unit controls
System controls
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Unit ControlsUnit Controls
• Pneumatic Controls - about 5%(PN**)
• No- controls- field installation of others controllers- about 5% (ENON)
• Factory Installation of others Controls- about 20% (FM0*)• DDC Controls - around 70% (DD**)
• Trane DDC (Communicates to a Trane-Trane-Trane System)
• Trane LonTalk DDC (designed to talk a language which is not proprietary to Trane)
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 45Version: 9/00
VAV systems
Optimized System Controls
• Optimal start• Optimal stop• Fan-pressure optimization• Supply-air-temperature reset• Ventilation optimization
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 46Version: 9/00
occupied hours
Optimal Start
6 AM noon 6 PMmid mid
systemon
systemoff
occupiedheating
setpoint
unoccupiedheating
setpoint
optimalstart
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 47Version: 9/00
occupied hours
Optimal Stop
6 AM noon 6 PMmid mid
systemon
systemoff
optimalstop
drift belowoccupiedsetpoint
occupiedheating
setpoint
unoccupiedheating
setpoint
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 48Version: 9/00
communicating BAS
VAV boxes
staticpressuresensor
PPsupplyfan
Fan-Pressure Optimization
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surge
fan-pressure optimization
Part-Load Energy Savings
airflow
sta
tic p
ressu
re
1000 rpm800 rpmfan-pressure optimization
energy savings
duct static pressure control
900 rpm
input power
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 50Version: 9/00
ASHRAE Standard 62.1-2004
Dynamic Reset of OA
• May reset OA intake flow (or zone OA flow) in response to:• Variations in zone population
(demand-controlled ventilation, or DCV)• Variations in ventilation efficiency
due to changes in airflow (ventilation reset)
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 51Version: 9/00
ventilation optimization
Zone Level: DCV
lounge restroom
storage office
office conference rm computer roomreception area ele
vato
rs
vestibule corridor
CO2
CO2
mechroom
OCC
OCCAHU
BAS
TOD TOD
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 52Version: 9/00
ventilation optimization
System Level: Ventilation Reset
OA
CO2 OCC OCC
• Required ventilation (TOD, OCC, CO2)• Actual primary airflow (flow sensor)
DDC/VAV terminals
SA RA
rooftop unitwith controls
• Reset outdoor airflow (Traq™ damper)
communicating BAS• New OA setpoint
…per ASHRAE 62
CO2TOD TOD
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 53Version: 9/00
rooftop VAV system
HVAC Energy Savings
MinneapolisLos AngelesAtlanta0
20
40
60
80
100
HV
AC
en
erg
y c
on
su
mp
tion
,%
of
base
optimized controlsconventional system
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 54Version: 9/00
Trane Control Systems Architecture
BuildingControl Unit
AH541MP580/1
CentralControl Panel 2
MP501/3
ReliaTel™
ZN5XX
VV550
Tracer™ Summit(Workstation Software)
Tracker™
ZN517ZN510/1ZN524
CentralControl Panel 3
ReliaTel™
MP503
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 55Version: 9/00
VAV systems
Sustaining Performance
• Centralized alarming, diagnostics, trending
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 56Version: 9/00
VAV systems
Sustaining Performance
• Centralized alarming, diagnostics, trending• Building operations, energy management,
commissioning, validation
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VAV systems
Sustaining Performance
• Centralized alarming, diagnostics, trending• Facility management services• Periodic commissioning and calibration
parallel, fan-poweredVAV terminal unit
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 58Version: 9/00
VAV systems
Sustaining Performance
• Centralized alarming, diagnostics, trending• Facility management services• Periodic commissioning and calibration• Wireless zone sensors
for flexibility
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• EA credit 1: Optimize Energy Performance
• TRACE 700 (90.1-2004, App G)
• EQ credit 1: Outdoor-Air Delivery Monitoring
• Ventilation optimization in Tracer Summit • CO2 sensors only in
densely-occupied zones• Traq dampers in IntelliPak
rooftop unit
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 60Version: 9/00
Summary
• What is Variable Air Volume (VAV)• Why(/Not) design VAV systems • What buildings utilize VAV• VAV system types and their components
• Changeover Bypass ( Varitrac)• True VAV ( Varitrane)• Single Zone VAV
• System control considerations• Leed and VAV
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 61Version: 9/00
VAV systems
QUESTIONS ??
American Standard, Inc. 2000 - All Rights Reserved File Name - Page 62Version: 9/00
VAV systems
THANK YOU
• Jeff Wotnosky – Trane Company
• 919-781-0458