Thermo Products OH5-85DXE Duct WORK/AIR Conditioning, Filters Mounted External to Furnace

All installations and services must be performed by qualified service personnel.

C. DUCT WORK/AIR CONDITIONING:

If the furnace is used in connection with summer air conditioning (cooling), the furnace should be installed parallel with or on the upstream side of the evaporator coil to avoid condensation in the furnace heat exchanger. If the cooling unit is installed with a parallel flow arrangement, dampers or other means used to control flow of air should be provided to prevent chilled air from entering the furnace. If such a damper is manually operated, it must be equipped with a means to prevent operation of either unit, unless the damper is in the full heat or cool position.

The duct system should again follow the current design standard of Air Conditioning Contractors of America (ACCA) or ASHRAE Fundamentals volume.The most common location for the A-shaped coil (A style) is shown in Fig. 2.

Fig 2: Acceptable locations for the air conditioner evaporator coil.

NOTICE: The minimum coil pan clearance for a sectional or drum type heat exchanger is three inches unless specified otherwise by the individual coil manufacturer.

D. FILTERS MOUNTED EXTERNAL TO FURNACE

On highboy furnaces, it is necessary to cut the return air opening in the side or rear casing, depending upon the needs of the specific installation.

The filter rack provided with the furnace, refer to Fig. 5, will serve as a template to scribe a mark for the return air opening on the casing. Place the filter rack on a side casing approximately one inch up from the bottom of the furnace and centered from side to side. Place the securing flange against the casing when locating the return air opening. For your convenience, (4) locator knock-outs have been placed at the proper locations on both the left and right side casings.

PLEASE NOTE: While scribing the return air opening, the filter rack can be held in position by tape or similar temporary means.

Position the open end of the filter rack so as to provide access for filter replacement. Once the filter rack is positioned correctly, scribe a line along the inside of the securing flange on three of the sides. To scribe a line on the fourth side (the open end), use the open end support as a guide.

Remove the filter rack and cut the return air opening in the casing. Now the filter rack can be anchored to the furnace with screws or pop-rivets through the securing flange of the filter rack.

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