Page 6
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of Cal-
ifornia to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient
outdoor air for combustion. Infiltration provided all the air
that was needed. In today’s homes, tight construction prac-
tices make it necessary to bring in air from outside for com-
bustion. Take into account that exhaust fans, appliance
vents, chimneys, and fireplaces force additional air that
could be used for combustion out of the house. Unless out-
side air is brought into the house for combustion, negative
pressure (outside pressure is greater than inside pressure)
will build to the point that a downdraft can occur in the fur-
nace vent pipe or chimney. As a result, combustion gases
enter the living space creating a potentially dangerous situ-
ation.
In the absence of local codes concerning air for combus-
tion and ventilation, use the guidelines and procedures in
this section to install G60UHV(X) furnaces to ensure effi-
cient and safe operation. You must consider combustion
air needs and requirements for exhaust vents and gas pip-
ing. A portion of this information has been reprinted with
permission from the National Fuel Gas Code
(ANSI-Z223.1). This reprinted material is not the complete
and official position of the ANSI on the referenced subject,
which is represented only by the standard in its entirety.
In Canada, refer to the standard CSA B149 installation
codes.
CAUTION
Do not install the furnace in a corrosive or contami-
nated atmosphere. Meet all combustion and ventila-
tion air requirements, as well as all local codes.
CAUTION
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rust-
ing and premature heat exchanger failure. Excessive
exposure to contaminated combustion air will result
in safety and performance related problems. Avoid
exposure to the following substances in the com-
bustion air supply:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
All gas-fired appliances require air for the combustion pro-
cess. If sufficient combustion air is not available, the fur-
nace or other appliances will operate inefficiently and un-
safely. Enough air must be provided to meet the needs of
all fuel-burning appliances and appliances such as ex-
haust fans which force air out of the house. When fire-
places, exhaust fans, or clothes dryers are used at the
same time as the furnace, much more air is necessary to
ensure proper combustion and to prevent a downdraft. In-
sufficient air causes incomplete combustion which can re-
sult in carbon monoxide.
In addition to providing combustion air, fresh outdoor air di-
lutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents
and other contaminants which can corrode furnace compo-
nents.
The requirements for providing air for combustion and ven-
tilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m
3
) per 1,000 Btu (.29 kW) per hour of the com-
bined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be un-
confined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
