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EN
W415-0297 / R / 02.23.21
9
installation
3.0 installation
3.1 determining confi ned or unconfi ned 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.
Add 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 air from the outdoors and expel their exhaust 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
B) Weather stripping has been added on openable windows and doors
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.
An 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. Without suffi cient fresh air for proper operation, poor fuel
combustion can result. Carbon Monoxide is a result of poor fuel
combustion.
If additional fresh air is required, use one of the methods
described in the National Fuel Gas Code, ANSI Z223.1 / NFPA54
or the applicable local code.
Room Volume = Length x Width x Height
Max BTU/hr = Room Volume x 1000 / 50
If for example:
The length of the rooms is 5 feet (1.5m),
The width of Room 1 is 10 feet (3.1m),
The width of Room 2 is 15 feet (4.6m),
The height of the rooms is 8 feet (2.4m).
Volume of Room 1: 5x10x8 = 400 cubic feet (11.16 cubic meters)
Volume of Room 2: 5x15x8 = 600 cubic feet (16.56 cubic meters)
EXAMPLE 1:
In this example, because there is no door to the adjoining room, the volume of the adjoining room may be added to the
volume of the room with the heater to get a total unconfi ned space.
The total unconfi ned space: 400 ft
3
(11.3m
3
)+ 600 ft
3
(17m
3
) = 1000 cubic feet (28.3m
3
).
Maximum BTU/h: [(1000x1000) ÷ 50] = 20,000 BTU/h
HEIGHT
ROOM 1
ROOM 2
WIDTH
LENGTH
• If the area in which the appliance may be operated is smaller than that defi ned as an unconfi ned 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.
!
WARNING
If there are no more fuel burning appliances within this space then the 30,000 BTU/h input of the appliance is suit-
able to be installed. This also assumes that the construction of this space is not unusually tight.
This would be considered a confi ned space since it can not support the 30,000 BTU/h input of the appliance and
it would be necessary to provide adequate combustion and ventilation air to Room 1.
EXAMPLE 2:
If in this example a solid door separates Room 1 from Room 2, the volume of Room 2 could not be used. In this case the
maximum BTU/h would be:
Maximum BTU/h: [(400x1000) ÷50] = 8,000 BTU/h
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