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This heater shall not be installed in a confined space or unusually
tight construction unless provisions are provided for adequate
combustion and ventilation air.
The
National Fuel Gas Code, ANSI Z223.1
defines a confined space
as a space whose volume is less than 50 cubic feet per 1,000 Btu per
hour (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 per hour (4.8
m3
per kw) of the aggregate input rating of all appliances installed in
that space. Rooms communicating directly with the space in which
the appliances are installed, through openings not furnished with
doors, are considered a part of the unconfined space.
The following example is for determining the volume of a typical
area in which the VFP30 may be located and for determining if
this area fits the definition of an unconfined space.
The maximum input of the VFP30 is 32,000 Btu per hour. Based
on the 50 cubic feet per 1,000 Btu per hour formula, the
minimum
area that is an unconfined space for installation of the VFP30 is
1,600 cubic feet, 50 cubic feet x 32 = 1,600 cubic feet. To determine
the cubic feet of the area in which the VFP30 is to be installed,
measure the length, width and height of the area. Example: The
area measures 17 feet in length, 12 feet in width and 8 feet in
height, the area is 1,632 cubic feet. The VFP30 can be installed
in this unconfined space with no requirement to provide additional
combustion and ventilation air.
PROVISIONS FOR ADEqUATE COMBUSTION & VENTILATION AIR
Warning:
If the area in which the heater 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.
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 the VFP30 heater is installed in a building of unusually tight
construction, adequate air for combustion, ventilation and dilu
-
tion of flue gases shall be provided in accordance with ANSI
Z223.1/NFPA54.
