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9
W415-1016 / B / 03.13.12
3.0 INSTALLATION
3.1 COMBUSTION AND VENTILATION AIR PROVISIONS
17.1A
This appliance shall not be installed in a confi ned space or unusually tight construction unless provisions are
provided for adequate combustion and ventilation air.
The National Fuel Gas Code, ANSI Z223.1 / NFPA 54 defi nes a confi ned space as a space whose volume is
less than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the aggregate input rating of all appliances
installed in that space and an unconfi ned space as a space whose volume is not less than 50 cubic feet per
1,000 Btu per hour (4.8 m3 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 unconfi ned space.
The WHVF31 is rated at 20,000 BTUs per hour for natural gas and propane and therefore requires a minimum
unconfi ned space of 1000 cubic feet.
3.2 DETERMINING CONFINED OR UNCONFINED SPACE
To determine the volume of the room where the appliance is to be installed, multiply the width x the length x
the ceiling height of that room measured in feet. If any adjoining rooms are connected by grilles or openings
such as kitchen pass-throughs, etc., the volume of those rooms may be added to the total.
Multiply the room volume by 1000 and divide this amount by 50 to determine the maximum BTU/hr that the
space can support with adequate combustion and ventilation air.
A
dd the Btu/hr of all fuel burning appliances located within the space such as gas furnace, gas water
appliance, etc. Do not include direct vent gas appliances which draw their input and output air from and to the
outdoors.
Unusually tight construction is defi ned as construction where:
A) Walls and ceilings exposed to the outside atmosphere have a continuous water vapour retarder with a
rating of 1 perm (6 x 10-11 kg per pa-sec-m2) or less 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 fl oors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical,
and gas lines, and at other openings.
A
n unvented room appliance is recommended for use as a secondary heat source rather than as a primary
source. Gas combustion produces water vapour which could occur at the rate of approximately one ounce of
water for every 1,000 BTU/hr of gas input. During the cold weather season, indoor humidity levels tend to be
low. Consequently, this water vapour can enhance the living space. However if a problem should occur:
A) Ensure suffi cient combustion and circulation air
B) Use a dehumidifi er
C) Do not use the unvented room appliance as a primary heat source
!
WARNING
IF THE AREA IN WHICH THE APPLIANCE 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 , AIR FOR COMBUSTION AND VENTILATION, OR THE
APPLICABLE LOCAL CODE.
IF THE AREA IN WHICH THE APPLIANCE MAY BE OPERATED DOES NOT MEET THE REQUIRED VOLUME
FOR INDOOR COMBUSTION AIR, COMBUSTION AND VENTILATION AIR SHALL BE PROVIDED BY ONE
OF THE METHODS DESCRIBED IN THE ANSI Z223.1 / NFPA 54, THE INTERNATIONAL FUEL GAS CODE,
OR APPLICABLE LOCAL CODES.
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