7
PREPARING FOR INSTALLATION
PRODUCING ADEQUATE 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 8 through 10 will help you classify your space and provide adequate
ventilation.
CONFINED AND UNCONFINED SPACE
A confined space is a space whose volume is less than 50 cu. ft. per 1,000 BTU/hr (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 cu. ft. per 1,000 BTU/hr (4.8 m³ 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 unconfined space. This heater shall not be installed in a confined 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 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
-11
kg per pa-sec-m²) or less with openings gasketed or sealed
b)
Weather stripping has been added on windows that can be opened and on doors
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” on page 9. If your home does not meet all of the three criteria
above, proceed to “Determining Fresh-Air Flow For Heater Location”.
CAUTION
: 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.
AIR FOR COMBUSTION AND VENTILATION
