Boiler manual: • Installation •
Before installing boiler (continued)
Combustion and ventilation air openings |
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Figure 3 Combustion and ventilation air openings | |
| — Boiler room below grade |
Adequate combustion and ventilation air must be provided to assure proper combustion and prevent possibility of flue gas leakage and carbon monoxide emissions, causing severe personal injury or death.
Do not install an exhaust fan in boiler room. Incor- rect burner operation can result.
When combustion and ventilation air enters through side wall openings, ensure that the open- ings comply with the requirements of Figure 3 and Figure 4.
Opening sizes must comply with state, provincial or local codes. In the absence of local requirements, use the National Fuel Gas Code, ANSI/NFPA 54). The following information is taken from ANSI/NFPA 54. For details and information not addressed below, refer to the standard.
Combustion air openings to inside
Required volume of interior spaces
ANSI/NFPA 54 allows combustion air to be supplied through openings to interior spaces if the volume of the connected interior spaces meets the minimum volume required by the standard.
The minimum volume of interior spaces can be taken as 50 cubic feet per 1,000 Btuh of all appliances in the spaces, or the minimum volume can be calculated using the formulas given in ANSI/NFPA 54. Excep- tion: If the air infiltration rate for the spaces is known to be less than
0.40air changes per hour, the minimum volume must be calculated as specified in the standard.
Inside air opening sizes and locations
For spaces that provide the minimum volume required by ANSI/ NFPA 54, the air openings must be sized per the following:
Combining spaces on the same story — Each opening shall have a minimum free area of 1 in2/1000 Btuh (2200 mm2/kW) of the total input rating of all appliances in the space but not less than 100 in2 (0.06 m2). One opening shall commence within 12 inches (300 mm) of the top, and one opening shall commence within 12 inches (300
mm)of the bottom, of the enclosure. The minimum dimension of air openings shall be not less than 3 inches (80 mm).
Combining spaces in different stories — The volumes of spaces in different stories shall be considered as communicating spaces where such spaces are connected by one or more openings in doors or floors having a total minimum free area of 2 in2/1000 Btuh (4400 mm2/kW) of total input rating of all appliances.
Part No.
Figure 4 Combustion and ventilation air openings
—Boiler room partially or completely above grade
Combustion air openings to outside
Outdoor combustion air can be taken through per- manent openings (TWO or ONE), as described in the following. The minimum dimension of air openings shall not be less than 3 inches (80 mm).
Outside openings: TWO permanent openings method
Two permanent openings, one commencing within 12 inches (300 mm) of the top and one commencing within 12 inches (300 mm) of the bottom of the enclo- sure shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that
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