interlocked with the boiler to prevent boiler operation if the dampers are closed.
Combustion air openings must never be blocked or obstructed in any manner.
The boiler room must be at a positive or neutral pressure relative to the outdoors. A negative in the boiler room will result in downdraft problems and incomplete combustion due to the lack of air.
WARNING!
Failure to provide an adequate air supply will result in boiler damage and hazardous conditions in the building (fire and asphyxiation hazard as well as equipment damage).
1.6.1COMBUSTION AIR OPENINGS:
The design of combustion air openings MUST comply with local and/or State codes or the authority having jurisdiction. As a minimum, combustion air openings to the boiler room shall be provided as follows:
Note:
Combustion air provided solely from an indoor source is discouraged. No dimension for a round or rectangular opening shall be less than 3”.
Two Permanent Opening Method
One opening starting within 12” of the top of the boiler room and one starting within 12” of the bottom of the boiler room shall be provided. The openings shall be open directly to the outside or ducted directly to the outside.
When directly open to the outside or ducted to the outside by vertical ducts, each opening or duct shall have a minimum fee open area of 1 in2 per 4000 BTU total input rating of the boiler(s) in the room.
If ducted to the outside through horizontal ducts, each opening or duct shall have a minimum free area of 1 in2 per 2000 BTU total input rating of the boiler(s) in the room.
5
Date: 8-4-2010
Revision: 0
Form: 2396
One Permanent Opening Method
One opening commencing within 12” of the top of the room shall be provided. The opening shall be directly to the outside or shall be ducted to the outside with a horizontal or vertical duct.
The opening or duct shall have a minimum free area of:
1 in2 / 3000 BTU /hour of the total input ratting of all appliances (boilers) in the room.
Not less than the sum of the areas of all vent connectors in the room. A “vent connector” is defined as the pipe or duct that connects a fuel burning appliance to a vent or chimney.
Additional area must be provided for other air consuming equipment in the room.
Mechanical Air Supply Systems
The combustion air supply may be provided by a mechanical air supply system. If utilized, the combustion air must be provided from the outside at a minimum rate of 0.35 ft3/min. for every 1000 Btu/hr. input for all appliances located in the space.
If exhaust fans are utilized, additional air shall be provided to replace the exhausted air.
Each boiler and other appliance must be interlocked to prevent operation when the mechanical air supply system is not in operation.
If the combustion air is provided by a buildings mechanical ventilation system, the system shall be sized to provide the specified combustion air in addition to the ventilation air requirements.
1.6.2LOUVERS, GRILLES, AND SCREENS
Louvers and Grilles:
The required size of openings for combustion, ventilation, and dilution air shall e based on the net free area of each opening. Where the free area through a design of louver, grille, or screen is know, it shall be used in calculating the size opening required to provide the free area
