cut main furnace casing to attach supply side air duct, humidifier,
or other accessories. All accessories MUST be connected external
to furnace main casing.
RETURN AIR CONNECTIONS
Never connect return-air ducts to the back of the furnace.
Return-air duct connections on furnace side(s) permitted in
upflow applications only. A failure to follow this warning
could result in fire, personal injury, or death.
Upflow Furnaces
The return-air duct must be connected to bottom, sides (left or
right), or a combination of bottom and side(s) of main furnace
casing. Bypass humidifier may be attached into unused side return
air portion of the furnace casing. DO NOT connect any portion of
return-air duct to back of furnace casing.
Downflow and Horizontal Furnaces
The return-air duct must be connected to return-air opening
provided. DO NOT cut into casing sides or back to attach any
portion of return-air duct. Bypass humidifier connections should
be made at ductwork or coil casing sides exterior to furnace.
Step 5—Filter Arrangement
Never operate unit without a filter or with filter access door
removed. Failure to follow this caution will result in inter-
mittent unit operation or performance satisfaction.
The air filter arrangement will vary due to application, furnace
orientation, and filter type. The filter may be installed in an
external Filter/Media cabinet (if provided) or the furnace blower
compartment. Factory supplied washable filters are shipped in the
blower compartment.
If a factory-supplied external Filter/Media cabinet is provided,
instructions for its application, assembly, and installation are
packaged with the cabinet. The Filter/Media cabinet can be used
with the factory-supplied washable filter or a factory-specified
high-efficiency disposable filter (see cabinet instructions).
If installing the filter in the furnace blower compartment, deter-
mine location for filter and relocate filter retaining wire, if
necessary. See Table 2 to determine correct filter size for desired
filter location. Table 2 indicates filter size, location, and quantity
shipped with this furnace. See Fig. 2 for location and size of
bottom and side return-air openings.
Use care when cutting support rods in filters to protect against
flying pieces and sharp rod ends. Wear safety glasses, gloves,
and appropiate protective clothing. Failure to follow this
caution will result in intermittent personal injury.
For airflow requirements above 1800 CFM, see Air Delivery
table in Product Data literature for specific use of single side
inlets. The use of both side inlets, a combination of 1 side and
the bottom, or the bottom only will ensure adequate return air
openings for airflow requirements above 1800 CFM. Failure
to follow this caution will result in intermittent unit operation
or performance satisfaction.
NOTE: Side return-air openings can ONLY be used in UPFLOW
configurations. Install filter(s) as shown in Fig. 24.
For bottom return-air applications, filter may need to be cut to fit
some furnace widths. Install filter as shown in Fig. 25.
NOTE: Remove and discard bottom closure panel when bottom
inlet is used.
Step 6—Bottom Closure Panel
These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. This panel MUST be in place when side
return air is used.
To remove bottom closure panel, perform following:
1. Tilt or raise furnace and remove 2 screws holding front filler
panel. (See Fig. 26.)
2. Rotate front filler panel downward to release holding tabs.
3. Remove bottom closure panel.
4. Reinstall front filler panel and screws.
Step 7—Gas Piping
Gas piping must be installed in accordance with national and local
codes. Refer to NFGC in the U.S. Canadian installations must be
made in accordance with NSCNGPIC and all authorities having
jurisdiction. Gas supply line should be a separate line running
directly from meter to furnace, if possible. Refer to Table 3 for
recommended gas pipe sizing. Risers must be used to connect to
furnace and to meter. Support all gas piping with appropriate
straps, hangers, etc. Use a minimum of 1 hanger every 6 ft. Joint
compound (pipe dope) should be applied sparingly and only to
male threads of joints. Pipe dope must be resistant to propane gas.
Table 2—Filter Information
AIR FILTER LOCATED IN BLOWER COMPARTMENT
Furnace
Casing
Width (In.)
Filter Size (In.)
Filter Type
Framed
Side Return Bottom Return
17-1/2 (1) 16 X 25 X 1† (1) 16 X 25 X 1† Cleanable
21 (1) 16 X 25 X 1* (1) 20 X 25 X 1† Cleanable
24-1/2 (1 or 2) 16 X 25 X 1* (1) 24 X 25 X 1† Cleanable
* Filters may be field modified by cutting filter material and support rods (3) in
filters. Alternate sizes can be ordered from your distributor or dealer.
† Factory-provided with furnace.
Fig. 24—Filter Installed for Side Inlet
A93045
FILTER
RETAINER
WASHABLE
FILTER
18
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