Operation & Installation Manual 09/2002

Horizontal Furnaces

Connect supply-air duct to supply air opening on furnace. The supply-air duct attachment must ONLY be connected to furnace supply/outlet or air conditioning coil casing (when used). DO NOT 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

The furnace and its return air system shall be designed and installed so that negative pressure created by the air circulating fan cannot affect another appliance’s combustion air supply or act to mix products of combustion with circulating air. The air circulating fan of the furnace, if installed in an enclosure communicating with another fuel-burning appliance not of the direct-vent type, shall be operable only when any door or panel covering an opening in the furnace fan compartment or in a return air plenum on ducts is in the closed position.

Table 2—Filter Information

AIR FILTER LOCATED IN BLOWER COMPARTMENT

FURNACE

CASING

WIDTH (IN.)

17-1/2

FILTER SIZE (IN.)*

Side Return

(1) 16 X 25 X 1†

Bottom Return

FILTER

TYPE

(1) 16 X 25 X 1† Cleanable

21

24-1/2

(1) 16 X 25 X 1 (1) 20 X 25 X 1† Cleanable

(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 and additional filters may be ordered from your dealer.

† Factory-provided with furnace.

Use care when cutting support rods in filters to protect against flying pieces and sharp rod ends. Wear safety glasses, gloves, and appropriate protective clothing. Failure to follow this caution could result in personal injury.

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

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.

NOTE: Side return-air openings can ONLY be used in UPFLOW configurations. Install filter(s) as shown in Fig. 23. Bottom return-air opening may be used with all 4 orientations. Filter may need to be cut to fit some furnace widths. Install filter as shown in

Fig. 24.

WASHABLE

FILTER

FILTER

RETAINER

Never operate unit without a filter or with filter access door removed. Failure to follow this warning can cause fire, personal injury, or death.

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, determine 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.

18

A93045

Fig. 23—Filter Installed for Side Inlet

NOTE: Remove and discard bottom closure panel when bottom inlet is used.

Step 6—Bottom Closure Panel

This furnace is shipped with bottom enclosure 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 the following:

1. Tilt or raise furnace and remove 2 screws holding front filler panel. (See Fig. 25.)

2. Rotate front filler panel downward to release holding tabs.

3. Remove bottom closure panel.

4. Reinstall front filler panel and screws.