NFPA 54 National Fuel Gas

Code

BoilerManufacture

r

ANSI Standards

LocalCodes

Vent Manufacture

r

Understanding ANSI StandardsUnderstanding ANSI StandardsUnderstanding ANSI StandardsUnderstanding ANSI Standards

Negative Positive

Non-condensing

Condensing

VENTINGVENTING

II

IIII

IVStatic Pressure in Vent

Above Dew Point

Below Dew Point

Understanding ANSI StandardsUnderstanding ANSI StandardsUnderstanding ANSI StandardsUnderstanding ANSI Standards

Negative Positive

Non-condensing

Condensing

VENTINGVENTING

II

IIII

IV

NFGC Airtight

AirtightCorrosion Resistant

Corrosion Resistant

Make sure the

equipment and venting

system match.

Determine the type of equipment installed (Category I, II, III, or IV).

Vent category specifies whether the vent system operates under a negative pressure or a positive pressure, and if the products of combustion condense into a liquid in the flue.

(ANSI) Vent System Categories

(ANSI) Vent System Categories

IV

III

II

I

Appliance Designation

•AtmosphericDraft Diverter

•Fan Assisted

Negative Positive

Non-Condensing

Condensing

•Forced Draft

•Fan Assisted•Fan Assisted

•Fan Assisted

Check that the proper venting material is used (B-vent, pressure stack, AL29-4C etc.).

IV

III

II

I

•Forced DraftUL103 P-Stack

Welded Steel

•AtmosphericB-Vent

Masonry

•Fan AssistedB-Vent

Masonry (interior)

Acceptable Vent Material

AL29-4C double wall

•Fan Assisted

(86 – 90 % efficiency)

•Condensing

(90+ efficiency)

AL29-4C single wall

CPVC (tested with appliance)

(85 – 90 % efficiency)

AL29-4C double wall

•Direct VentAL29-4C double wall

Check appliance draft requirements. Codes require that the draft must meet the

manufacturers specifications.

-0.05” -0.06” -0.08”

-0.02” -0.03” -0.03”

0.00” -0.01” -0.01”

-0.14” -0.17” -0.20”

20’

6’10’

50’

1,000 MBH

Fan Assist Cat. I (10” B-Vent) 95°F 60°F 25°F

Chimney Pressures - Steady StateChimney Pressures - Steady State

Vertical Venting with a Metal Chimney System and Inside Air

Futera II

Category I

Futera III

Category II

Modulating Boiler SystemModulating Boiler SystemModulating Boiler SystemModulating Boiler System

-0.13

-0.12

-0.11

-0.1

-0.09

-0.08

-0.07

-0.06

-0.05

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

Ap

plian

ce

Ou

tlet

Pre

ssu

re (

in.

W.C

.)

Blr

1 s

tart

s

Blr

2 s

tart

s

Blr

3 s

tart

s

Blr

4 s

tart

s

Blr

2 s

top

s

Blr

3 s

top

s

Blr

4 s

top

s

Vent = 30’ vert./10’ horiz., 18” diam.

4 Fan-assisted Cat I boilers with 1,000 MBH input each

Constant ambient of 60°F

Draft variations in a modulating boiler system

Barometric DampersBarometric Dampers

• Draft Hoods and Barometric Dampers will maintain

the boiler’s operating efficiency, but now excess air

will be needed to be pulled into the equipment room.

– Consider automatic dampers, or a– Modulating exhaust system, or– Modulating dampers

Horizontal Vent using Inside Air

Futera II

Category I

Side Wall Venting using Inside Air

Futera II

Category III

Z223.1-51-2002 (Venting of Equipment)10.3.4.6 Mechanical Draft Systems.

The exit terminals of mechanical draft systems shall be not less than 7ft above grade where located adjacent to public walkways.

PublicWalkway

Not less

than 7’

Side wall ventingSide wall venting

Z223.1-56 (Venting of Equipment)7.8 Venting System Location.

(a) A Venting system shall terminate at least 3 ft (0.9 m) above any forced air inlet located within 10 ft (3.1 m).

Exception No. 1: This provision shall not apply to the combustion air intake of a direct-vent appliance.

Exception No. 2: This provision shall not apply to the separation of circulating air inlet and flue gas discharge of listed outdoor appliances.

Forced AirInlet

If Lessthan 10’

3’ Min.

Side wall ventingSide wall venting

Alexander Conca

Z223.1-56 (Venting of Equipment)7.8 Venting System Location.

(b) The venting system of other than a direct-vent appliance shall terminate at least 4 ft (1.2 m) below, 4 ft (1.2 m) horizontally from, or 1 ft (30 cm) above any door, window, or gravity air inlet into any building. The bottom of the vent terminal shall be located at least 12 in. (30 cm) above grade.

Gravity Air Inlet

Gravity Air Inlet

GravityAirInlet

4’Min.

12”Min.

4’Min.

Side wall ventingSide wall venting

Z223.1-56 (Venting of Equipment)

As required for Clearance to Combustibles or Snow Load.

As required forClearance toCombustibles

ParapetRoof

Rooftop ventingRooftop ventingRooftop ventingRooftop venting

2 feet above anything within 10 feet & no less than 3 feet above roof

Common Code ViolationsCommon Code ViolationsNFPA 54 c99 Sec. 7.6.1(d)NFPA 54 c99 Sec. 7.6.1(d)

The total horizontal distance of a vent plus the The total horizontal distance of a vent plus the horizontal vent connector serving Category 1 horizontal vent connector serving Category 1 appliancesappliances Shall Not Be Greater Than 75%Shall Not Be Greater Than 75% of the of the vertical height of the vent.vertical height of the vent.

Common Code ViolationsCommon Code ViolationsNFPA 54 c99 Sec. 10.2.2,4,5NFPA 54 c99 Sec. 10.2.2,4,5

The length of the common vent connector, offset, The length of the common vent connector, offset, and breechingand breeching Shall Not Exceed 1 1/2 ft. (18”)Shall Not Exceed 1 1/2 ft. (18”) for for each inch of common vent diameter.each inch of common vent diameter.

DiameterDiameter

Not Greater than 1.5 Ft. per Not Greater than 1.5 Ft. per Every Inch of DiameterEvery Inch of Diameter

Common Code ViolationsCommon Code ViolationsNFPA 54 c99 Sec. 10.2.8, 15NFPA 54 c99 Sec. 10.2.8, 15

The flow area of the vertical ventThe flow area of the vertical vent Shall Not Exceed Shall Not Exceed Seven (7) TimesSeven (7) Times the flow area of the smallest listed the flow area of the smallest listed appliance.appliance.

Not Greater than 7 times Not Greater than 7 times the smallest Outlet Cross the smallest Outlet Cross Sectional AreaSectional Area

Smallest DiameterSmallest Diameter

Common Code ViolationsCommon Code ViolationsNFPA 54 Z223.1NFPA 54 Z223.1

Connector Rise Not Adequate for Breeching DiameterConnector Rise Not Adequate for Breeching Diameter

RiserRiser

3 Ft. Minimum Vertical Rise on 8900 Units3 Ft. Minimum Vertical Rise on 8900 Units

5 Ft. Minimum Vertical Rise on 8800 Units5 Ft. Minimum Vertical Rise on 8800 Units

Common Code ViolationsCommon Code ViolationsNFPA 54 v99 Sec. 7.10.4(b)NFPA 54 v99 Sec. 7.10.4(b)

Vent Connectors serving equipment vented by Vent Connectors serving equipment vented by natural draftnatural draft Shall Not Be Connected Into Any Shall Not Be Connected Into Any PortionPortion of mechanical draft systems under positive of mechanical draft systems under positive pressure.pressure.

Common Code ViolationsCommon Code ViolationsNFPA 54 c99 Sec. 7.3.4(b)NFPA 54 c99 Sec. 7.3.4(b)

Forced draft systems and all portions of induced Forced draft systems and all portions of induced draft systems under positive pressure shall be draft systems under positive pressure shall be designed and installed so as to prevent leakage designed and installed so as to prevent leakage of flue gasses into the building.of flue gasses into the building.

Combustion AirCombustion Air

Make sure the proper amount of combustion air is available.

  

Air from Outside or Inside the BuildingNFPA 54 - National Fuel Gas Code, Outside Air for Combustion National Fire Protection Association, NFPA Gas fuels:

Minimum No. openings required 2

Indoor opening, sq. in./Btu h 1/1000

Outdoor opening, sq. in./Btu h 1/4000

Vertical ducts, sq. in./Btu h 1/4000

Horizontal ducts, sq. in./Btu h 1/2000

Ducts same as opening yes

Louver & grill free area opening

CFM per 1000 BTU’s (atmospheric) .50

CFM per 1000 BTU’s (fan assist)without barometric .27

with barometric .35

- Single Outdoor opening: 1/3000