ALL FURNACE INSTALLATIONS
MUST COMPLY WITH THE
NATIONAL FUEL GAS CODE,
CAN/CSA B149.1 (CANADA) AND
LOCAL CODES TO PROVIDE ADE-
QUATE COMBUSTION AND VENTI-
LATION AIR FOR THE FURNACE.
FAILURE TO DO SO CAN RESULT
IN EXPLOSION, FIRE, PROPERTY
DAMAGE, CARBON MONOXIDE
POISONING, PERSONAL INJURY
OR DEATH.
Combustion air requirements are
determined by whether the furnace
is in an open (unconfined) area or in
a confined space such as a closet or
small room.
FURNACE LOCATED IN AN
UNCONFINED SPACE
Using indoor air for combustion.
An unconfined space must have at
least 50 cubic feet for each 1,000
BTUH of the total input for all
appliances in the space. Here are a
few examples of the room sizes
required for different inputs. The
sizes are based on 8 foot ceilings.
See Table 2.
If the open space containing the fur-
nace is in a building constructed to
severely limit outside air infiltration
(contemporary energy efficient con-
struction methods), outside air may
still be required for the furnace to
operate and vent properly. Outside
air openings should be sized the
same as for a confined space.
COMBUSTION AIR
ALWAYS PROVIDE THIS FUR-
NACE AND ANY OTHER FUEL
BURNING APPLIANCE WITH
ENOUGH FRESH AIR FOR
PROPER COMBUSTION AND
VENTILATION OF THE FLUE
GASES. MOST BUILDING
CODES REQUIRE THAT OUT-
SIDE AIR BE SUPPLIED INTO
THE FURNACE AREA. FAIL-
URE TO DO SO CAN CAUSE
DEATH FROM CARBON
MONOXIDE POISONING.
Provide adequate facilities for com-
bustion and ventilation air in accor-
dance with section 5.3, Air for
Combustion and Ventilation of the
National Fuel Gas Code, ANSI
Z223.1 - latest edition; CAN/CGA
B149.1 and .2, or applicable provi-
sions of the local building codes.
These combustion and ventilation
facilities must not be obstructed.
IMPORTANT: Air for combustion and
ventilation must not come from a
corrosive atmosphere. Any furnace
failure due to corrosive elements in
the atmosphere is excluded from
warranty coverage.
The following types of installation (but
not limited to the following) REQUIRE
OUTDOOR AIR for combustion, due
to chemical exposures:
• Commercial buildings
• Buildings with indoor pools
• Furnaces installed in laundry
rooms
• Furnaces in hobby or craft rooms
• Furnaces installed near chemical
storage areas.
Exposure to the following substances
in the combustion air supply (but not
limited to the following) also
REQUIRE OUTDOOR AIR for com-
bustion:
• Permanent wave solutions
• Chlorinated waxes and cleaners
• Chlorine-based swimming pool
chemicals
• Water softening chemicals
• De-icing salts or chemicals
• Carbon Tetrachloride
• Halogen type refrigerants
• Cleaning solvents (such as per-
chloroethylene)
• Printing inks, paint removers,
varnishes, etc.
•
Hydrochloric acid
• Cements and glues
• Anti-static fabric softeners for
clothes dryers
• Masonry acid washing materials
Combustion air must be free of acid
forming chemicals such as sulphur,
fluorine, and chlorine. These ele-
ments are found in aerosol sprays,
detergents, bleaches, cleaning sol-
vents, air fresheners, paint and var-
nish removers, refrigerants and many
other commercial and household
products. Vapors from these products
when burned in a gas flame form acid
compounds. The acid compounds
increase the dew point temperature
of the flue products and produce
highly corrosive condensate.
TABLE 2
UNCONFINED SPACE DIMENSIONS
BTUH Minimum Sq. Feet Typical Room Size
Input With 8 foot Ceiling
60,000
375
15' x 25' OR 19' x 20'
75,000
469
15' x 32' OR 20' x 24'
90,000
563
20' x 28' OR 24' x 24'
105,000
657
20' x 33' OR 26' x 25'
120,000
750
25' x 30' OR 24' x 32'
!
WARNING
!
WARNING
NON-DIRECT VENT PIPE INSTALLATION
(FOR VERTICAL TERMINATIONS ONLY)
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