99
AIR FOR COMBUSTION AND VENTILATION
WARNING: This heater shall not be installed in a conned space or unusually tight construction unless
provisions are provided for adequate combustion and ventilation air. Read the following instructions to ensure
proper fresh air for this and other fuel-burning appliances in your home.
Providing Adequate Ventilation
This heater shall not be installed in a room or space unless the required volume of indoor combustion air is provided
by the method described in the NATIONAL FUEL GAS CODE, ANSI Z223.1/NFPA 54, the INTERNATIONAL FUEL
GAS CODE, or applicable local codes.
The following are excerpts from National Fuel Gas Code, ANSI Z223.1/ NFPA 54. Air for Combustion and Ventilation.
All spaces in homes fall into one of the three following ventilation classications:
1. Unusually Tight Construction
2. Unconned Space
3. Conned Space
The information on pages 9 through 11 will help you classify your space and provide adequate ventilation.
Conned and Unconned Space
The National Fuel Gas Code, ANSI Z223.1/NFPA 54 denes a conned space as a space whose volume is less than
50 cu. ft. per 1,000 BTU/hr (4.8 m^3 per kw) of the aggregate input rating of all appliances installed in that space and
an unconned space as a space whose volume is not less than 50 cubic feet per 1,000 BTU/hr (4.8 m^3 per kw) of the
aggregate input rating of all appliances installed in that space. Rooms connecting directly with the space in which the
appliances are installed*, through openings not furnished with doors, are considered a part of the unconned space.
This heater shall not be installed in a conned space or unusually tight construction unless provisions are provided for
adequate combustion and ventilation air.
* Adjoining rooms are connecting only if there are doorless passageways or ventilation grills between them.
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 dened as construction where:
Walls and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating of
one perm (6×10
-11
kg per pa-sec-m
2
) or less with openings gasketed or sealed and
Weather stripping has been added on openable windows and on doors and
Caulking or sealants are applied to areas such as joints around window and door frames, between sole plates
and oors, between wall ceiling joints, between wall panels, at penetrations for plumbing, electrical, and gas
lines, and at other openings.
If your home meets all of the three criteria above, you must provide additional fresh air. See “Ventilation Air From
Outdoors”. If your home does not meet all of the three criteria above, proceed to “Determining Fresh-Air Flow For
Heater Location”.
a)
b)
c)
