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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
California 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 USA
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient out
door air for combustion. Infiltration provided all the air that was
needed. In today's homes, tight construction practices make it
necessary to bring in air from outside for combustion. Take into
account that exhaust fans, appliance vents, chimneys, and
fireplaces force additional air that could be used for combus
tion out of the house. Unless outside air is brought into the
house for combustion, negative pressure (outside pressure is
greater than inside pressure) will build to the point that a down
draft can occur in the furnace vent pipe or chimney. As a result,
combustion gases enter the living space creating a potentially
dangerous situation.
In the absence of local codes concerning air for combustion
and ventilation, use the guidelines and procedures in this
section to install G24M furnaces to ensure efficient and safe
operation. You must consider combustion air needs and re
quirements for exhaust vents and gas piping. A portion of this
information has been reprinted with permission from the Na
tional Fuel Gas Code (ANSIZ223.1). This reprinted material
is not the complete and official position of the ANSI on the ref
erenced subject, which is represented only by the standard in
its entirety.
In Canada, refer to the standard CAN/CGA B149.1 and
B149.2 installation codes.
CAUTION
Do not install furnace in a corrosive or contaminated
atmosphere. Meet all combustion and ventilation air
requirements, as well as all local codes.
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
California 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 USA
All gasfired appliances require air for the combustion pro
cess. If sufficient combustion air is not available, the fur
nace or other appliance will operate inefficiently and un
safely. Enough air must be provided to meet the needs of all
fuelburning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, ex
haust fans, or clothes dryers are used at the same time as
the furnace, much more air is required to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result 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
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air
from outside section.
