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4. WATER VAPOR: A BY-PRODUCT OF UNVENTED ROOM HEATERS
Water vapor is a by-product of gas combustion. An unvented room heater produces approximately 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 dehumidifier may be used to help lower the water vapor content of
he air.
3. Do not use an unvented room heater as the primary heat source
5. AIR FOR COMBUSTION AND VENTILATION
WARNING:
This heater shall not be installed in a confined space or unusually tight construction
unless provisions are provided for adequate combustion and ventilation air. Read the following
instructions to ensure proper fresh air for this and other fuel-burning appliances in your home.
Providing Adequate Ventilation
This heater shall not be installed in a room or space unless the required volume of indoor combustion air
is provided by the method described in the NATIONAL FUEL GAS CODE, ANSI Z223.1/NFPA 54, the
INTERNATIONAL FUEL GAS CODE, or applicable local codes. The following are excerpts from National
Fuel Gas Code, ANSI Z223.1/ NFPA 54. Air for Combustion and Ventilation. All spaces in homes fall into
one of the three following ventilation classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
The information on the followed pages will help you classify your space and provide adequate ventilation.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223 .1/NFPA 54 defines a confined space as a space whose volume
is less than 50 cu. ft. per 1,000 BTU/hr (4.8 m
3
per kw) of the aggregate input rating of all appliances
installed in that space and an unconfined space as a space whose volume is not less than 50 cubic feet
per 1,000 BTU/hr (4.8 m
3
per kw) of the aggregate input rating of all appliances installed in that space.
Rooms connecting directly with the space in which the appliances are installed, through openings not
furnished with doors, are considered a part of the unconfined space.
This heater shall not be installed in a confined space or unusually tight construction unless provisions are
provided for adequate combustion and ventilation air. Adjoining rooms are connecting only if there are
odorless passageways or ventilation grills between them.
Summary of Contents for WDFT060-VF-IR
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