# 47860A005
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operation. All venting must be in accordance with the codes
having jurisdiction in the area and these instructions.
G1D91BT, G1D93BT, and CG90TB models can be installed
as either direct vent or non-direct vent units. A direct vent
(two pipe) installation requires that all the air necessary for
combustion be supplied from outside the dwelling through
an air intake pipe. A non-direct vent (one pipe) installation
uses air from inside the dwelling for combustion.
The furnace is shipped with the air inlet pipe terminated to
the top panel for either inside or outside combustion air. An
inlet air restrictor plate (see Figure 2) is supplied with this
furnace and can be found in the plastic bag containing these
Installation Instructions and the User’s Information Manual.
This inlet restrictor plate must be used in all installations
using inside air for combustion (non-direct vent).
To install the inlet restrictor plate:
1. Install the restrictor plate in the inlet pipe collar in the
top panel of the furnace.
2. Insert a 3" section of PVC pipe (field supplied) into the
collar. Use high temperature RTV sealant to attach
PVC pipe to collar.
3. Attach a 90° elbow (field supplied) to the PVC pipe.
Use high temperature RTV sealant to attach elbow to
PVC pipe.
Two different sized inlet restrictor plates are supplied with
the furnace (2" and 3"). Use the proper restrictor plate for
the furnace model.
Contaminated Combustion Air
Excessive exposure to contaminated combustion air will
result in safety and performance related problems. The
recommended source of combustion air is outdoor air.
However, the use of indoor air in most applications is
acceptable if the following guidelines are followed:
1. If the furnace is installed in a confined space, it is
recommended that the necessary combustion air come
from the outdoors by way of an attic, crawl space, air
duct, or direct opening.
2. If indoor combustion air is used, there must be no
exposure to the substances listed in Item 5.
3. All provisions for indoor combustion air must meet the
requirements for combustion air indicated in the
National Fuel Gas Code, ANSI Z223.1/NFPA 54
(latest edition), and/or any applicable local codes. In
Canada, see CSA B149.1, Natural Gas and Propane
Installation Codes (latest edition).
4. The following types of installation may require
outdoor
air
for combustion, due to chemical exposures:
•
Commercial buildings
•
Buildings with indoor pools
•
Furnaces installed in laundry rooms
•
Furnaces installed in hobby or craft rooms
•
Furnaces installed near chemical storage areas
5. Exposure to the following substances in the combustion
air supply may also require
outdoor air
for combustion:
•
Permanent wave solutions
•
Chlorinated waxes and cleaners
•
Chlorine-based swimming pool chemicals
•
Water softening chemicals
•
Deicing salts or chemicals
•
Carbon tetrachloride
•
Halogen-type refrigerants
•
Cleaning solvents (such as perchloroethylene)
•
Printing inks, paint removers, varnishes, etc.
•
Cements and glues
•
Antistatic fabric softeners for clothes dryers
•
Masonry acid washing materials
•
Chlorinated laundry products
•
Hydrochloric acid
Venting
The high efficiency of this furnace is accomplished by the
removal of both sensible and latent heat from the flue
gases. The removal of latent heat results in the condensa-
tion of moisture in the flue gases. This condensation occurs
in the secondary heat exchanger and in the vent system.
Therefore, this furnace requires special venting consider-
ations and the instructions must be followed to insure proper
Also included in the plastic bag containing the inlet air
restriction plate is a flue pipe screen (see Figure 2). In all
installations, this screen should be installed at the termina-
tion of the flue pipe and is designed to keep objects out of
the flue pipe.
Flue Pipe Screen
The flue pipe screen should be
installed at the termination of the flue
pipe in all installations.
Figure 2
Inlet Air Restrictor Plate
The inlet air restrictor plate
must
be
installed in all installations using inside
air for combustion (non-direct vent).
