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AIR FOR COMBUSTION AND VENTILATION
Providing adequate ventilation
The following is excerpts from National Fuel Gas Code. NFPA 54/ANSI Z223.1, 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 7 through 11 will help you classify your space and provide ad-
equate 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 (6x10
with openings gasketed or sealed and
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 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, page 11.
If your home does not meet all of the three criteria above, proceed to page 9.
Confined Space and Unconfined Space
The National Fuel Gas Code (ANSI Z223.1, 1992 Section 5.3) defines a confined space as a
space whose volume is less than 50 cubic feet per 1,000 BTU per hour (4.8m
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 (4.8m
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.
-11
8
per pa-sec-m
2
) or less
3
per kw) of the
3
per kw) of
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