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VENTING GAS APPLIANCES

NFPA 54 CODE

Better Buildings: Better Business

Robert Parkhurst

March 3, 2017

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Objectives

• Standardize terminology

• Examine gas piping size and safety

• Simplify design rules

• Selection of table(s) for sizing of venting

– Category I appliances

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Starting Together

• National Fire Protection Association

– Over 300 on Laundry List of Codes

• NFPA 70

– Better know as NEC (National Electric Code)

• NFPA 54

– National Fuel Gas Code

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What Does It Address

• NFPA 54

– Requirements cover the installation and operation of fuel gas piping systems, appliances, equipment, and related accessories, with rules for piping systems materials and components, piping system testing and purging, combustion and ventilation air supply, and venting of gas-fired appliances and equipment.

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Chapter 3 Definitions

• Draft (?)

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Chapter 3 Definitions

• Vented Appliance (?)

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Chapter 3 Definitions

• Category I

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Chapter 3 Definitions

• Category IV

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Chapter 3 Definitions

• Category I

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Chapter 3 Definitions

• Fan Assisted

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Chapter 3 Definitions

Chimney Flue

Appliance Flue

Vent Connector

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Chapter 3 Definitions

L (lateral)H (height)

R (rise)

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Chapter 3 Definitions

• NA -- Not Applicable or Not Allowed

Vent configuration that is not allowed due to

potential for condensate formation or

pressurization of the venting system or that is not

applicable due to physical or geometric restraints.

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Chapter 5 Gas Piping

• Copper

– Type K or Type L

• Steel -- Black Iron Pipe

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Chapter 5 Gas Piping• CSST Corrugated Stainless Steel Tubing

– Safety

– Bonding

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Chapter 7 Gas Piping

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Chapter 6 Gas Piping Sizing

• Inlet Pressure

• Pressure Drop

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Chapter 6 Gas Piping Sizing

cubic feet per hour

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Chapter 9 Installation

• Combustion air requirements

• Not Category I

– Follow manufacturer’s instructions

• Category I

– Inside air if large enough volume

– Outside air is optional for small volumes

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Chapter 9 Installation

• Indoor Air Requirements

• 80000 Furnace and 40000 Water Heater

– 120 x 50 = 6000 ft3

– 800 ft2 @ 7 ½ ft ceiling

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Chapter 9 Installation

• Indoor Air Requirements <.4 ACH

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Chapter 9 Installation

• Indoor Air Requirements

– Tested at .3 ACH

• 80000 Fan Assisted Furnace

– 15/.3 x 80 = 4000

• 40000 Water Heater

– 21/.3 x 40 = 2800

• 6800 ft3 or about 907 ft2

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Chapter 12 Venting of Appliances

• Venting systems shall be designed and

constructed to convey all flue and vent

gases to the outdoors.

• Exceptions

– Ranges, cook tops

– Refrigerators

– Clothes Dryers (follow 10.4)

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Mechanical Draft Venting

• Install according to both the appliance

manufacturer’s and venting system

manufacturer’s instructions

• Seal all seams under positive pressure

• No mixing with natural venting

• Must have safety built in to shut off gas to

burners if venting system is not working

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Category IV Direct VentingIntake and Exhaust Pipes

• PVC allowed (140°F limit)

• Furnace/Water Heater/Boiler Manual

– Size of pipe and allowable lengths (support)

• Terminations

– Through wall or through roof

– 12” above grade or anticipated snow level

– In same pressure location

– Concentric venting kit

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Category IV Direct VentingIntake and Exhaust Pipes

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Category IV Direct VentingIntake and Exhaust Pipes

• Exhaust 12” from doors & windows

• Exhaust 3’ from intake of water heater

• Intake 3’ from water heater exhaust

• Intake 3’ from dryer exhaust

• 7’ above public walkways

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Category IV Direct VentingIntake and Exhaust Pipes

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Category IV Direct VentingIntake and Exhaust Pipes

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Venting of Category I AppliancesThe 70s

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Venting of Category I Appliances

• Masonry Chimneys

– Flue no smaller than appliance flue

– Flue no more than 7 times appliance flue

– Must be lined per NFPA 211

– Termination

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Venting of Category I Appliances

• Masonry Chimneys with Liner

– Liner sizing in Chapter 13 tables

– Labeled as for gas use only

• Space around liner can not be used for:

– Venting other appliances

– Combustion air

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Venting of Category I Appliances

• Gas Vents

– Termination

– 7x rule

– Not smaller

– Labeled in

chimney

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Chapter 13 Sizing of Category I

Venting Systems• Vent Connectors

– Slope ¼ in/ft upward to chimney/vent

– Not smaller than appliance flue

– Up to 2 sizes larger than appliance flue

– Length depends on type for single appliance

• Single wall 75% of vent height

• B-Vent 100% of vent height

– 18”/inch diameter for multiple appliances

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Chapter 13 Sizing of Category I

Venting Systems

• 13.1 Single Appliances Tables

– B-Vent or masonry chimney

– Type of connector

• Sizing based on:

– Height of vent/chimney

– Lateral length of connector

• 13.2 Multiple Appliances Tables

• Rise of connector for sizing not lateral

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Chapter 13 Sizing of Category I

Venting Systems

• Natural Draft Appliance

– Maximum BTU for size listed

• Fan Assisted Appliance

– Minimum BTU for size listed

– Maximum BTU for size listed

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13.1 (a) B Double-Wall Gas Vent

• B-Vent directly connected to appliance

• Corrugated Chimney Liners

– Max capacity reduced to 80% listed

• Single-wall Metal Connector from

appliance

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13.1 (b) B Double-Wall Gas Vent

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13.1 (c) Masonry Chimney

• Type B Double-Wall Connector from

appliance

• Single-wall Metal Connector from

appliance

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13.1 (d) Masonry Chimney

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Chapter 13 Elbows

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Table 13.1(a) B-Vent

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Table 13.1(b) B-Vent Single Connector

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Table 13.1(c) Masonry B-Vent Connector

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Table 13.1(d) Masonry Single Connector

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Table 13.1(c) and 13.1(d) Chimney Area

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13.2 (a) B Double-Wall Gas Vent

• B-Vent Connectors from appliances

• Corrugated Chimney Liners

– Max capacity reduced to 80% listed

• Single-wall Metal Connectors from

appliances

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13.2 (b) B Double-Wall Gas Vent

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13.2 (c) Masonry Chimney

• Type B Double-Wall Connectors from

appliances

• Single-wall Metal Connectors from

appliances

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13.2 (d) Masonry Chimney

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13.2 Common Connector

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Table 13.2(c) Masonry B-Vent Connector

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13.2(a) Vent Capacities

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13.2(b) Vent Capacities

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13.2(c) Vent Capacities

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13.2(d) Vent Capacities

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Sizing Examples

Single Appliance

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Questions

Thank You