18
18-IN. (457.2 mm)
MINIMUM TO BURNERS
A93044
Fig. 17 -- Installation in a Garage
NON-DIRECT VENT (1-PIPE) APPLICATION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in intermittent
unit operation.
Do not install furnace in a corrosive or contaminated
atmosphere. Make sure all combustion and circulating air
requirements are met.
CAUTION
!
Refer to the AIR FOR COMBUSTION AND VENTILATION
section for details.
AIR FOR COMBUSTION AND
VENTILATION
Provisions for adequate combustion, ventilation, and dilution air
must be provided in accordance with:
S
U.S. Installations:
Section 9.3 NFPA 54/ANSI Z223.1--2009,
Air for Combustion and Ventilation and applicable provisions
of the local building codes.
S
Canadian Installations:
Part 8 of CAN/CS----B149.1--05.
Venting Systems and Air Supply for Appliances and all
authorities having jurisdiction.
FURNACE CORROSION HAZARD
Failure to follow this warning could result in reduced furnace
component life.
Air for combustion must not be contaminated by halogen
compounds, which include fluoride, chloride, bromide, and
iodide. These elements could corrode heat exchangers and
shorten furnace life. Air contaminants are found in aerosol
sprays, detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products.
!
WARNING
The following types of furnace installations may require
OUTDOOR AIR for combustion due to chemical exposures:
S
Commercial buildings
S
Buildings with indoor pools
S
Laundry rooms
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Hobby or craft rooms, and
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Chemical storage areas
If air is exposed to the following substances, it should not be
used for combustion air, and outdoor air may be required
for combustion:
S
Permanent wave solutions
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Chlorinated waxes and cleaners
S
Chlorine based swimming pool chemicals
S
Water softening chemicals
S
De-icing salts or chemicals
S
Carbon tetrachloride
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Halogen type refrigerants
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Cleaning solvents (such as perchloroethylene)
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Printing inks, paint removers, varnishes, etc.
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Hydrochloric acid
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Cements and glues
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Antistatic fabric softeners for clothes dryers
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Masonry acid washing materials
All fuel-burning equipment must be supplied with air for fuel
combustion. Sufficient air
must
be provided to avoid negative
pressure in the equipment room or space. A positive seal
must
be
made between the furnace cabinet and the return-air duct to
prevent pulling air from the burner area and from draft
safeguard opening.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury
or death.
The operation of exhaust fans, kitchen ventilation fans, clothes
dryers, attic exhaust fans or fireplaces could create a
NEGATIVE PRESSURE CONDITION at the furnace.
Make-up air MUST be provided for the ventilation devices, in
addition to that required by the furnace. Refer to the Carbon
Monoxide Poisoning Hazard warning in the venting section of
these instructions to determine if an adequate amount of
make-up air is available.
!
WARNING
The requirements for combustion and ventilation air depend upon
whether or not the furnace is located in a space having a volume
of at least 50 cubic feet per 1,000 Btuh input rating for all gas
appliances installed in the space.
S
Spaces having less than 50 cubic feet per 1,000 Btuh require
the
OUTDOOR COMBUSTION AIR
METHOD.
S
Spaces having at least 50 cubic feet per 1,000 Btuh may use
the
INDOOR COMBUSTION AIR, STANDARD or
KNOWN AIR INFILTRATION
METHOD.
Outdoor Combustion Air
Method
1. Provide the space with sufficient air for proper
combustion, ventilation, and dilution of flue gases using
permanent horizontal or vertical duct(s) or opening(s)
directly communicating with the outdoors or spaces that
freely communicate with the outdoors.
2. Fig. 18 illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air openings to the outdoors.
a. One opening
MUST
commence within 12 in. (305
mm) of the ceiling and the second opening MUST
commence within 12 in. (305 mm) of the floor.
b. Size openings and ducts per Fig. 18 and Table 1.
c. TWO HORIZONTAL DUCTS require 1 square inch of
free area per 2,000 Btuh (1,100 mm
2
/kW) of combined
input for all gas appliances in the space per Fig. 18 and
Table 1.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
square inch of free area per 4,000 Btuh (550 mm
2
/kW)
for combined input of all gas appliances in the space
per Fig. 18 and Table 1.
3. ONE OUTDOOR OPENING requires:
a. 1 square inch of free area per 3,000 Btuh (734 mm
2
/kW)
for combined input of all gas appliances in the space
per Table 1 and 11.
58MEC
