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PRODUCING ADEQUATE
VENTILATION
This section is for residential or manufactured (mobile) installation
“This heater shall not be installed in a confined space or unusually tight construction unless pro-
visions are adequate combustion and ventilation air.”
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 (4.8m
3
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 (4.8m
3
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.
“WARNING: IF THE AREA IN WHICH THE HEATER MAY BE OPERATED IS
SMALLER THAN THAT DEFINED AS AN UNCONFINED SPACE OR IF THE
BUILDING IS OF UNUSUALLY TIGHT CONSTRUCTION, PROVIDE ADEQUATE
COMBUSTION AND VENTILATION AIR BY ONE OF THE METHODS DESCRIBED
IN THE NATIONAL FUEL GAS CODE, ANSI Z223.1/NFPA 54, SECTION 5.3 OR
APPLICABLE LOCAL CODES.”
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 1 perm (6 x 10
-11
kg per pa-sec-m
2
) or less with openings gasketed or sealed;
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.
NOTE: SOME AREAS IN THE UNITED STATES HAVE HIGHER REQUIREMENTS
FOR CUBIC FEET PER 1000 BTU/ HOUR INPUT. (EX. CINCINNATI, OHIO CODES
REQUIRE 70 CUBIC FEET). CHECK YOUR LOCAL CODE BEFORE
INSTALLATION.
DETERMINING FRESH-AIR FLOW FOR
HEATER LOCATION
DETERMINE IF YOU HAVE A CONFINED OR UNCONFINED SPACE
Use this worksheet to determine if you have confined or unconfined space.
SPACE: Includes the room in which you will install heater plus adjoining rooms with
doorless passageways or ventilation grills between the rooms.
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