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19.2
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 uncon
fi
ned space.
The total uncon
fi
ned space: 800 + 1200 = 2000 cubic feet.
Maximum BTU/h: 2000x1000 = 40,000 BTU/h
50
19.3
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: 800x1000 = 16,000 BTU/h
50
If there are no more fuel burning appliances within this space then the 6,000 BTU/h input of the appliance is
suitable to be installed. This also assumes that the construction of this space is not unusually tight.
19.1A
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 suf
fi
cient combustion and circulation air
B)
Use a dehumidi
fi
er
C)
Do not use the unvented room appliance as a primary heat source
Without suf
fi
cient fresh air for proper operation, poor fuel combustion can result. Carbon Monoxide is a result
of poor combustion.
If additional fresh air is required, use one of the methods described in the National Fuel
Gas Code, ANSI Z223.1, Section 5.3 or the applicable local code.
Room Volume = Length x Width x Height
Max BTU/hr = Room Volume x 1000 / 50
LENGTH
HEIGHT
ROOM 2
ROOM 1
WIDTH
If for example:
The length of the rooms is 10 feet,
The width of Room 1 is 10 feet,
The width of Room 2 is 15 feet,
The height of the rooms is 8 feet.
The volume of Room 1: 10x10x8 = 800 cubic feet
The volume of Room 2: 10x15x8 = 1200 cubic feet
If there are no more fuel burning appliances within this space then the 6,000 BTU/h input of the appliance is
suitable to be installed. This also assumes that the construction of this space is not unusually tight.
