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200213-01B
Water vapor is a by-product of gas combus-
tion. An unvented room heater produces ap-
proximately one (1) ounce (30 mL) of water for
every 1,000 BTUs (0.3 KWs) of gas input per
hour. Unvented room heaters are recommended
as supplemental heat (a room) rather than a
primary heat source (an entire house). In most
supplemental heat applications, the water vapor
does not create a problem. In most applications,
the water vapor enhances the low humidity
atmosphere experienced during cold weather.
The following steps will help ensure that water
vapor does not become a problem.
1. Be sure the heater is sized properly for the
application, including ample combustion
air and circulation air.
2. If high humidity is experienced, a dehu-
midifier may be used to help lower the
water vapor content of the air.
3. Do not use an unvented room heater as
the primary heat source.
AIR FOR COMBUSTION AND VENTILATION
WARNING: This heater shall
not be installed in a confined
space or unusually tight con-
struction unless provisions are
provided for adequate combus-
tion and ventilation air. Read the
following instructions to insure
proper fresh air for this and other
fuel-burning appliances in your
home.
Today’s homes are built more energy efficient
than ever. New materials, increased insulation
and new construction methods help reduce
heat loss in homes. Home owners weather
strip and caulk around windows and doors
to keep the cold air out and the warm air in.
During heating months, home owners want
their homes as airtight as possible.
While it is good to make your home energy
efficient, your home needs to breathe. Fresh
air must enter your home. All fuel-burning ap-
pliances need fresh air for proper combustion
and ventilation.
Exhaust fans, fireplaces, clothes dryers and
fuel burning appliances draw air from the
house to operate. You must provide adequate
fresh air for these appliances. This will insure
proper venting of vented fuel-burning appli-
ances.
WATER VAPOR: A BY-PRODUCT OF
UNVENTED ROOM HEATERS
WARNING: This heater shall
not be installed in a room or
space unless the required vol-
ume of indoor combustion air
is provided by the method de-
scribed in the National Fuel Gas
Code, ANSI Z223.1/NFPA 54, the
International Fuel Gas Code, or
applicable local codes.
WARNING: If the area in which
the heater may be operated does
not meet the required volume for
indoor combustion air, combus-
tion and ventilation air shall be
provided by one of the methods
described in the National Fuel
Gas Code, ANSI Z223.1/NFPA 54,
the International Fuel Gas Code,
or applicable local codes.
