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This section is used for residential installation or mobile home installation.
UNCONFINED SPACE:
An unconfined space has a minimum air volume of 50 cubic feet for each 1,000 BTU/Hr (4.8m
3
per
Kw) input rating of all appliances in space (Cubic feet equals Length x Width x Height of space).
Include adjoining rooms only if there are doorless passageways or ventilation grills between rooms.
CONFINED SPACE:
“The National Fuel Gas Code defines unusually tight construction 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.
“WARNING: If the area in which heater may be operated is smaller than that defined as an
unconfined space, provide adequate combustion and ventilation air by one of
methods
described in National Fuel Gas Code, ANSI Z223.1, 1992, Section 5.3”
NOTICE: Information on provisions for adequate combustion and ventilation air are located in
unvented room heater ‘s installation instructions. The unvented room heater’s instructions
must be followed exactly.
PRODUCING ADEQUATE VENTILATION
DETERMINING FRESH-AIR FLOW FOR
HEATER LOCATION
DETERMINE IF YOU HAVE UNUSUALLY TIGHT CONSTRUCTION OR UNCONFINED SPACE
Use this worksheet to determine if you have a confined or unconfined space.
SPACE:
Include
room in which you will install heater plus adjoining rooms with doorless
passageways or ventilation grills between rooms.
1. Determine the volume of space (length x width x height).
Length x Width x Height= ________ cu.ft. (volume of space)
EXAMPLE:
20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) =
2560 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or openings, add volume of these
rooms to total volume of space.
2. Divide the space volume by 50 cubic feet to determine maximum BTU/Hr space
can support.
________
(volume of space) / 50 cu. ft = (maximum BTU/Hr space can support)
EXAMPLE:
2560 cu. ft. (volume of space) / 50 cu. ft. = 51.2 or
51200 (maximum BTU/Hr space can support.)
