507281-06
Page 24 of 58
Issue 1724
Figure 28. Typical Air Intake Pipe Connections
Upflow Non-Direct Vent Applications
NOTE:
Debris screen and elbow may be rotated, so that screen
may be positioned to face forward or to either side.
Figure 29. Typical Air Intake Pipe Connections
Horizontal Non-Direct Vent Applications
(Horizontal Right-Hand Air Discharge Application
Shown)
NOTE:
Debris screen may be positioned straight
out (preferred) or with an elbow rotated to face
down.
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.
3. Use field-provided materials and the factory-provided
air intake screen to route the intake piping as shown in
Figure 28 or Figure 29. 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 to either side in the
upflow position, and either straight out or downward in
the horizontal position.
The air intake piping must not terminate too close
to the flooring or a platform. Ensure that the intake
air inlet will not be obstructed by loose insulation
or other items that may clog the debris screen.
4. If intake air is drawn from a ventilated attic (Figure
30) or ventilated crawlspace (Figure 31) the exhaust
vent length must not exceed those listed in Table 5C.
If 3” diameter pipe is used, reduce to 2” diameter pipe
at the termination point to accommodate the debris
screen.
5. Use a sheet metal screw to secure the intake pipe to
the connector, if desired.
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 exhaust air as well as the maximum volume of
combustion air required for all gas appliances serviced
by this space.
CAUTION
Figure 30.
Equipment in Confined Space
(Inlet Air from Ventilated Attic and Outlet Air to
Outside)
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.
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