Air For Combustion
and Ventilation
WARNING: This firebox shall not be installed in a confined space or unusually tight con- struction unless provisions are provided for adequate combus- tion and ventilation air. Read the following instructions to insure proper fresh air for this and other
Today’s homes are built more energy efficient than ever. New materials, increased insulation and new construction methods help reduce heat loss in homes. Home owners weather strip and caulk around windows and doors to keep the cold air out and the warm air in. During heating months, home owners want their homes as airtight as possible. While it is good to make your home energy effi- cient, your home needs to breathe. Fresh air must enter your home. All
Exhaust fans, fireboxes, clothes dryers and fuel burning appliances draw air from the house to operate. You must provide adequate fresh air for these appliances. This will insure proper venting of vented
PROVIDING ADEQUATE
VENTILATION
The following are excerpts from National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation.
All spaces in homes fall into one of the three fol- lowing ventilation classifications:
1.Unusually Tight Construction
2.Unconfined Space
3.Confined Space
The information on pages 7 through 9 will help you classify your space and provide adequate ventilation.
Unusually Tight Construction
The air that leaks around doors and windows may provide enough fresh air for combustion and ventilation. However, in buildings of unusually tight construction, you must provide additional fresh air.
Unusually tight construction is defined as construction where:
a.walls and ceilings exposed to the out- side atmosphere have a continuous water vapor retarder with a rating of one perm (6 x
b.weather stripping has been added on openable windows and doors and
c.caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between
If your home meets all of the three criteria above, you must provide additional fresh air. See Ventilation Air From Outdoors, page 9.
If your home does not meet all of the three criteria above, proceed to Determining
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1/NFPA 54 defines a confined space as a space whose volume is less than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space and an unconfined space as a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space. Rooms com- municating directly with the space in which the appliances are installed*, through openings not furnished with doors, are considered a part of the unconfined space.
*Adjoining rooms are communicating only if there are doorless passageways or ventilation grills between them.