Provisions For Adequate Combustion And Ventilation Air - Empire Comfort Systems VFD20MS30N-1 Installation Instructions And Owner's Manual

PROVISIONS FOR ADEQUATE COMBUSTION & VENTILATION AIR
This heater shall not be installed in a confined space or unusually
tight construction unless provisions are provided for adequate
combustion and ventilation air.
A confined space is an area with volume less than 50 cubic feet per
1,000 Btuh of the combined input rates of all appliances 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 combus-
tion 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 appliances in the space.
The following example is for determining the volume of a typical
area in which the VFD30 may be located and for determining if this
area fits the definition of an unconfined space.
The maximum input of the VFD30 is 25,000 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 VFD30 is
1,250 cubic feet, 50 cubic feet x 25 = 1,250 cubic feet. To determine
the cubic feet of the area in which the VFD30 is to be installed,
measure the length, width and height of the area. Example: The
area measures 16 feet in length, 10 feet in width and 8 feet in
height, the area is 1,280 cubic feet. The VFD30 can be installed
in this unconfined space with no requirement to provide additional
combustion and ventilation air.
42605-3-0621
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 com-
bustion and ventilation air by one of the methods described
in the 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 VFD30 heater is installed in a building of unusually tight con-
struction, adequate air for combustion, ventilation and dilution of flue
gases shall be provided in accordance with ANSI Z223.1/NFPA54.
WARNING
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