Water Vapor: A By-Product Of Unvented Room Heaters; Provisions For Adequate Combustion & Ventilation Air - Empire Comfort Systems VFLL38FP30L Installation Instructions And Owner's Manual

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 ounce (30ml) of water
for every 1,000 BTU's (.3KW's) 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.
PROVISIONS FOR ADEQUATE COMBUSTION & VENTILATION AIR
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 Z23.1/
NFPA 54, the International Fuel Gas Code, or applicable local
codes.
Installation in a Confined Space
A confined space is an area with volume less than 50 cubic
feet per 1,000 Btuh of the combined input rates of all fireplaces
drawing combustion air from that space. Small areas such as
equipment rooms are confined spaces. Furnaces installed in
a confined space which supply heated air to areas outside the
space must draw return air from outside the space through tightly
sealed return air ducts. A confined space must have 2 openings
into the space for combustion air. One opening must be within
12 inches of the ceiling and the other must be within 12 inches
of the floor. The required sizing of these openings is determined
by whether inside or outside air is used to support combustion,
the method by which the air is brought to the space (vertical or
horizontal duct) and by the total input rate of all fireplaces in the
space.
Unusually Tight Construction
The air that leaks around doors and windows may provide
enough fresh air for combustion and ventilation. However, in
buildings of unusually tight construction, you must provide
additional fresh air.
Unusually tight construction is defined as construction
where:
a. Walls and ceilings exposed to the outside atmosphere
have a continuous water vapor retarder with a rating of
one perm 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
floors, between wall-ceiling joints, between wall panels, at
penetrations for plumbing, electrical, and gas lines, and at
other openings.
If your home meets all of the three criteria above, you must
provide additional fresh air. See "Ventilation Air From
Outdoors," page 14.
Determining if you Have a Confined or Unconfined Space
Use this worksheet to determine if you have a confined or
unconfined space.
Space: Includes the room in which you will install fireplace plus
any adjoining rooms with doorless passageways or ventilation
grills between the rooms.
34846-2-1016
The following steps will help insure that water vapor does not
become a problem.
1. Be sure the heater is sized properly for the application, includ-
ing 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 the air.
3. Do not use an unvented room heater as the primary heat
source.
1. Determine the volume of the space (length x width x height).
Length x Width x Height =
space)
Example: Space size 16 ft. (length) x 10 ft. (width) x 8 ft.
(ceiling height) = 1,280 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with
grills or openings, add the volume of these rooms to the total
volume of the space.
2. Divide the space volume by 50 cubic feet to determine the
maximum BTU/Hr the space can support.
(volume of space) ÷ 50 cu. ft. = (maximum
BTU/Hr the space can support)
Example: 1,280 cu. ft. (volume of space) ÷ 50 cu. ft. = 25.6 or
25,600 (maximum BTU/Hr the space can support)
3. Add the BTU/Hr of all fuel burning fireplaces in the space.
Vent-free fireplace
Gas water fireplace
Gas furnace
Vented gas fireplace
Gas fireplace logs
Other gas fireplaces*
Total
Example: Vented gas fireplace
Vent-free fireplace + 18,000
Total
*Do not include direct-vent gas fireplaces. Direct vent draws
combustion air from the outdoors and vents to the outdoors.
4. Compare the maximum BTU/Hr the space can support with
the actual amount of BTU/Hr used.
BTU/Hr (maximum the space can support)
BTU/Hr (actual amount of BTU/Hr used)
Example:
25,600 BTU/Hr (maximum the space can support)
38,000 BTU/Hr (actual amount of BTU/Hr used)
If the area in which the fireplace 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 applicable local codes.
cu. ft. (volume of
BTU/Hr
BTU/Hr
BTU/Hr
BTU/Hr
BTU/Hr
+ BTU/Hr
= BTU/Hr
20,000 BTU/Hr
BTU/Hr
= 38,000 BTU/Hr
WARNING
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