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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 7 for pipe sizes.
Follow the next 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 as shown
in Figure 24. 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.
Page 18 of 53
Pipe size determined in table 7.
2"
2"
3"
TRANSITION
*2"
* When transitioning up in pipe size, use the shortest length of 2" PVC pipe possible.
NOTE: Exhaust pipe and intake pipe must be the same diameter.
Figure 23. Typical Intake Pipe Connections (Direct Vent Applications)
2"
2"
2"
or
NOTE: 1-1/2" Vent Pipe
Diameter Allowed Only
on 045/070 Units
1-1/2"
or
TRANSITION
*2"
*2"
2.
If intake air is drawn from a ventilated attic (Figure
25) or ventilated crawlspace (Figure 26) the exhaust
vent length must not exceed those listed in Table 8. If
3" diameter pipe is used, reduce to 2" diameter pipe
at the termination point to accommodate the debris
screen.
3.
Use cement to secure the intake pipe to the connector,
if desired.
NOTE: Debris screen and elbow may be rotated so that the
screen may be positioned to face forward or to either side.
Figure 24. Typical Air Intake Pipe Connections
Issue 1933
INTAKE
EXHAUST
TOP VIEW
TRANSITION
*2"
3"
(Provided)
Non-Direct Vent Applications
Intake
Debris
Screen
507735-03
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