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Intake Piping
This furnace may be installed in either direct vent or non-
direct vent applications. In non-direct vent applications,
when intake air will be drawn into the furnace from the
surrounding space, the indoor air quality must be considered.
Guidelines listed in Combustion, Dilution and Ventilation Air
section must be followed.
Follow the next two steps when installing the unit in Direct
Vent applications, where combustion air is taken from
outdoors and flue gases are discharged outdoors. The
provided air intake screen must not be used in direct
vent applications (outdoors).
1. Use cement or a sheet metal screw to secure the intake
pipe to the inlet air connector.
2. Route piping to outside of structure. Continue with
installation following instructions given in general guide
lines for piping terminations and intake and exhaust
piping terminations for direct vent sections. Refer to
Table 7A-7C for pipe sizes.
Follow the next two steps when installing the unit in Non-
Direct Vent applications where combustion air is taken
from indoors and flue gases are discharged outdoors.
1. Use field-provided materials and the factory-provided
air intake screen to route the intake piping. Maintain a
minimum clearance of 3" (76 mm) around the air intake
opening. The air intake opening (with the protective
screen) should always be directed forward, or sideways.
2. If intake air is drawn from a ventilated crawlspace
(Figure 25) or ventilated attic (Figure 24) the exhaust
vent length must not exceed those listed in Table 7C.
If 3" diameter pipe is used, reduce to 2" diameter pipe
to accommodate the debris screen.
3. Use a sheet metal screw to secure the intake pipe to
the connector, if desired.
Equipment in Confined Space
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
Figure 24
507052-04
General Guidelines for Vent Terminations
In Non-Direct Vent applications, combustion air is taken from
indoors and the flue gases are discharged to the outdoors.
This unit is then classified as a non-direct vent, Category
IV gas furnace.
In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the outdoors.
This unit is then classified as a direct vent, Category IV gas
furnace.
In both Non-Direct Vent and Direct Vent applications, the
vent termination is limited by local building codes. In the
absence of local codes, refer to the current National Fuel
Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current
CSA-B149 Natural Gas and Propane Installation Codes in
Canada for details.
Position termination according to location given in Figure 26
or 27. In addition, position termination so it is free from any
obstructions and 12" above the average snow accumulation.
At vent termination, care must be taken to maintain
protective coatings over building materials (prolonged
exposure to exhaust condensate can destroy protective
coatings). It is recommended that the exhaust outlet not be
located within 6 feet (1.8 m) of a condensing unit because
the condensate can damage the painted coating.
Issue 1621
Figure 25
Page 21 of 58
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