Allied A97UH2E - Page 36

508433-01Issue 2345Page 36 of 70
Intake Piping
The A97UH2E 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 and 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 ue gases are discharged outdoors. The provided air intake screen must not be used in direct vent applications
(outdoors).
1. Use transition solvent 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 guidelines for
piping terminations and intake and exhaust piping terminations for direct vent sections. Refer to Table 13A through
Table 13C for pipe sizes.
Figure 21.
TYPICAL INTAKE PIPE CONNECTIONS IN UPFLOW DIRECT OR
NON-DIRECT VENT APPLICATIONS
2”
2”
2”
2”
or
AIR
INTAKE
2”
TRANSITION
3”
*2”
Pipe size determined in Table 5
or
* 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 22.
TYPICAL INTAKE PIPE CONNECTIONS IN HORIZONTAL DIRECT OR NON-DIRECT VENT
APPLICATION (RIGHT-HAND DISCHARGE SHOWN)
2”
2”
2”
2”
or
2”
AIR
INTAKE
TRANSITION
3”
*2”
*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.