508134-01
Issue 2045
Page 30 of 56
Intake Piping
The A93DF1E / 92G1DFE 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 flue 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 11A and Table 11B 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 as shown
in Figure 24. Maintain a minimum clearance of 3”
(76mm) 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 attic (Figure 25)
or ventilated crawlspace (Figure 26) the exhaust vent
length must not exceed those listed in Table 11B. If
3” diameter pipe is used, reduce to 2” diameter pipe
at the termination point to accommodate the debris
screen.
3.
Use a sheet metal screw to secure the intake pipe to
the connector, if desired.
AIR
INTAKE
SCREEN
(Provided)
NOTE
- Air intake screen and elbow may be rotated, so that
screen may be positioned to face forward or to either side.
Figure 24. Typical Air Intake Pipe Connections
Non-Direct Vent Applications
If this unit is being installed in an application with
combustion air coming in from a space serviced by an
exhaust fan, power exhaust fan, or other device which
may create a negative pressure in the space, take care
when sizing the inlet air opening. The inlet air opening
must be sized to accommodate the maximum volume
of exhausted air as well as the maximum volume of
combustion air required for all gas appliances serviced
by this space.
CAUTION
Ventilation Louvers
Inlet Air
(Minimum 12 in.
(305mm) above
Attic Floor)
Roof Terminated
Exhaust Pipe
Furnace
*Intake Debris
Screen
(Provided)
* See Maximum Vent Lengths table
NOTE-The inlet and outlet air openings shall each have a
free area of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) per hour of the total input rating of all equipment
in the enclosure.
Figure 25.
Equipment in Confined Space
(Inlet Air from Ventilated Attic and Outlet Air to
Outside)