507769-05G / 31-5000656
Page 9 of 55
Issue 2223
Figure 8.
Equipment in Confined Space
(Inlet Air from Ventilated Attic and Outlet Air to
Outside)
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 9.
Equipment in Confined Space
(Inlet Air from Ventilated Crawl Space and Outlet Air
to Outside)
Roof Terminated
Exhaust Pipe
Furnace
Ventilation
Louvers
(Crawl Space)
*Intake Debris Screen Provided
Inlet Air
Minimum
12 in. (305mm)
above Crawl
Space Floor
Coupling or
3 in. to 2 in.
Transition
(Field 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.
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
Installation
Setting Equipment
Do not install the furnace on its front, back or in the
horizontal position. See Figure 11. Do no connect the
return air ducts to the back of the furnace. Doing so
will adversely affect the operation of the safety control
devices, which could result in personal injury or death.
CAUTION
Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection,
condensate trap and drain connections, and installation
and service clearances [24 inches (610 mm) at unit front].
The unit must be level from side to side. Tilt the unit slightly
(maximum 1/2 in. from level) from back to front to aid in the
draining of the heat exchanger. See Figure 12.
Shipping Bolt Removal
Units with a 1/2 hp & 3/4 hp blower motors are equipped
with three flexible legs and one rigid leg. The rigid leg
is equipped with a shipping bolt and a flat white plastic
washer (rather than the rubber mounting grommet used
with a flexible mounting leg). See Figure 10. The bolt and
washer must be removed before the furnace is placed into
operation. After the bolt and washer have been removed,
the rigid leg will not touch the blower housing.
Figure 10.
RIGID LEG
(Remove shipping bolt
and washer)
Units with 1/2 or 3/4 HP Blower Motor
NOTE:
These units may be equipped with a shipping pad
under the blower housing. Remove the shipping pad prior
to operation.
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or
alcove installations are shown in Figure 13.
Blower access panel must be securely in place when
blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into
living space resulting in personal injury or death.
WARNING