I.
LOCATION
A.
General
CAUTION:
Do not install furnace in a corrosive or
contaminated atmosphere. Make sure all combustion and
circulating air requirements are met.
CAUTION:
Do not use this furnace during construction
when adhesives, sealers, and/or new carpets are being
installed and curing. If the furnace is required during
construction, use clean outside air for combustion and
ventilation. Compounds of chlorine and fluorine, when
burned in combustion air, form acids which will cause
corrosion of the heat exchangers and metal vent system.
Some of these compounds are released from paneling and
dry wall adhesives, paints, thinners, masonry cleaning
materials, and many other solvents commonly used in the
construction process.
Excessive exposure to contaminated combustion air will
result in safety and performance related problems.
This furnace must be installed so the electrical components are
protected from water.
Locate furnace as near the center of the air distribution system and
chimney or vent as possible. The furnace should be installed as
level as possible. When a furnace is installed so that supply ducts
carry air to areas outside the space containing the furnace, return
air must also be handled by a duct(s) sealed to the furnace casing
and terminating outside the space containing the furnace.
Provide ample space for servicing and cleaning. Always comply
with minimum fire protection clearances shown on unit clearance
label. This furnace shall not be installed directly on carpeting, tile,
or any combustible material other than wood flooring.
B.
Location Relative to Cooling Equipment
The cooling coil must be installed parallel with or on downstream
side of furnace to avoid condensation in heat exchangers. When
installed parallel with a furnace, dampers or other means used to
control the flow of air must prevent chilled air from entering
furnace. If dampers are manually operated, they must be equipped
with means to prevent operation of either unit unless damper is in
full-heat or full-cool position.
C.
Hazardous Locations
When furnace is installed in a residential garage, it must be
installed so that burners and ignition source are located at least 18
in. above the floor. The furnace should be protected from physical
damage by vehicles. When furnace is installed in public garages,
airplane hangars, or other buildings having hazardous atmo-
spheres, the unit must be installed in accordance with recom-
mended good practice requirements of the National Fire Protection
Association, Inc.
II.
AIR FOR COMBUSTION AND VENTILATION
Provisions for adequate combustion and ventilation air must be
provided in accordance with Section 5.3, Air for Combustion and
Ventilation, of the NFGC or applicable provisions of the local
building codes.
Canadian installations must be in accordance with NSCNGPIC
and all authorities having jurisdiction.
CAUTION:
Air for combustion must not be contami-
nated by halogen compounds, which include fluoride,
chloride, bromide, and iodide. These elements are found
in aerosol sprays, detergents, bleaches, cleaning solvents,
salts, air fresheners, and other household products.
All fuel-burning equipment must be supplied with air for combus-
tion of fuel. Sufficient air MUST be provided to ensure there will
not be a negative pressure in the equipment room or space. In
addition, a positive seal MUST be made between furnace cabinet
and return-air duct to prevent pulling air from burner area and draft
safeguard opening into the circulating air.
CAUTION:
The operation of exhaust fans, kitchen ven-
tilation fans, clothes dryers, or fireplaces could create a
negative air pressure condition at the furnace. Make-up
air must be provided for these devices, in addition to that
required by the furnace.
Combustion air requirements are determined by whether furnace is
in an UNCONFINED or CONFINED space.
A.
Unconfined Space
An unconfined space must have at least 50 cu ft for each 1000
Btuh of input for all appliances (such as furnaces, clothes dryer,
water heaters, etc.) in the space.
For Example:
330AAV FURNACE HIGH-FIRE
INPUT BTUH
MINIMUM SQ FT WITH
7-1/2 FT CEILING
40,000
267
60,000
400
80,000
534
100,000
667
120,000
800
133,000
887
If the unconfined space is of unusually tight construction, air for
combustion and ventilation MUST come from either the outdoors
or spaces freely communicating with the outdoors. Combustion
and ventilation openings must be sized the same as for a confined
space as defined below. Return air must not be taken from the
room unless an equal or greater amount of air is supplied to the
room.
B.
Confined Space
A confined space is defined as a space whose volume is less than
50 cu ft per 1000 Btuh of total input ratings of all appliances
installed in that space. A confined space MUST have provisions
for supplying air for combustion, ventilation, and dilution of flue
gases using 1 of the following methods. (See Fig. 3 and Table 2.)
NOTE:
In determining free area of an opening, the blocking
effect of louvers, grilles, and screens must be considered. If free
area of louver or grille design is unknown, assume that wood
louvers have a 20 percent free area and metal louvers or grilles
have a 60 percent free area. Screens, when used, must not be
smaller than 1/4-in. mesh. Louvers and grilles must be constructed
so they cannot be closed.
The size of the openings depends upon whether air comes from
outside of the structure or an unconfined space inside the structure.
1. All air from inside the structure requires 2 openings (for
structures not usually tight):
a. Each opening MUST have at least 1 sq in. of free area
per 1000 Btuh of total input for all equipment within the
confined space, but not less than 100 sq in. per opening.
(See Fig. 3 and Table 2.) The minimum dimension of air
openings shall not be less than 3 in.
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