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AIR FOR COMBUSTION AND VENTILATION
Providing Adequate Ventilation
Determining
AIR FOR COMBUSTION AND VENTILATION
WARNING: This heater shall not be installed in a confined space or unusually tight construction un- less provisions are provided for adequate combus- tion and ventilation air. Read the following instruc- tions to insure proper fresh air for this and other fuel- burning appliances in your home.
Today’s homes are built more energy efficient than ever. New materi- als, 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 efficient, your home needs to breathe. Fresh air must enter your home. All
Exhaust fans, fireplaces, 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 following ventilation classifications:
1.Unusually Tight Construction
2.Unconfined Space
3.Confined Space
The information on pages 4 and 5 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 outside 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 Out- doors, page 5.
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 communicating 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.
DETERMINING FRESH-AIR FLOW FOR HEATER LOCATION
Determining if You Have a Confined or Unconfined Space
Use this work sheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install heater plus any adjoining rooms with doorless passageways or ventilation grills between the rooms.
1.Determine the volume of the space (length x width x height). Length x Width x Height = ___________ cu. ft. (volume of space)
Example: Space size 22 ft. (length) x 18 ft. (width) x 8 ft. (ceiling height) = 3168 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or open- ings, add the volume of these rooms to the total volume of the space.
2.Multiply the space volume by 20 to determine the maximum Btu/Hr the space can support.
__________ (volume of space) x 20 = (Maximum Btu/Hr the space
can support)
Example: 2560 cu. ft. (volume of space) x 20 = 51,200 (maximum Btu/Hr the space can support)
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