Duct System

B − Rear Return Air (Refer to figure 6)

REAR RETURN AIR FILTER BOX INSTALLATION

Size and install supply and return air duct system using in- dustry-approved standards that result in a quiet and low- static system with uniform air distribution.

UNIT

FILTER

ACCESS

PANEL

ADHESIVE-BACKED

FOAM TAPE

(Apply to filter box)

FILTER

ACCESS

PANEL

RETURN AIR

FILTER BOX

FOUR FILTERS (Filters may be also installed through top of frame)

Supply Air Plenum

Furnaces installed without a cooling coil require the installa- tion of a removable access panel in the supply air duct. The access panel should be large enough to permit inspection (ei- ther by smoke or reflected light) of the heat exchanger for leaks after installation. The furnace access panel must al- ways be in place when the furnace is operating and it must not allow leaks into the supply air duct system.

In applications requiring air conditioning, see installation instructions provided with C17-090/120 evaporator coil for supply air plenum size and connection.

Return Air Plenum

Return air must not be drawn from a room where this furnace, or any other gas appliance (i.e., a water heat- er), is installed. When return air is drawn from a room, a negative pressure is created in the room. If a gas ap- pliance is operating in a room with negative pressure, the flue products can be pulled back down the vent pipe and into the room. This reverse flow of the flue gas may result in incomplete combustion and the formation of carbon

REPOSITION REAR PANEL WITH FLANGES AS SHOWN. (Seal air-tight with adhesive-backed foam tape.)

FIGURE 6

1 − Determine the location of the furnace/filter box. NOTE − Filter box can be installed with right or left side filter access or top-rear filter access. Allow enough room when positioning the furnace for filter access.

2 − Remove the bottom-rear panel from the furnace and re-install on the bottom of the furnace as shown. Seal air-tight with adhesive-backed foam tape.

3 − Apply adhesive-backed foam tape to the filter box (side facing furnace) all around the opening. Refer to figure 6.

4 − Position the filter box over the furnace return air open- ing. The top of the filter box should be in the

tion and the filter box and the furnace edges flush at the sides and bottom.

5 − Fasten using self-drilling self-tapping screws provided with the filter box. Use the frame clearance holes as a guide.

6 − Install the four filters and the filter access door.

7 − Size the return air plenum to fit the filter box and then seal the joint air tight.

monoxide gas. This toxic gas might then be distributed throughout the house by the furnace duct system.

Size and install return air plenum as indicated in previous section.

Blower Motor / Drive Installation

A − Motor Installation

Refer to figure 7.

1 − Check the box on the rating plate to indicate which of the drive kits are being installed.

2 − Secure the blower motor to the motor base with the hardware provided.

3 − Slide the motor pulley onto the motor shaft and align with the blower pulley.

4 − Install the belt.

5 − Refer to

blower RPM setting and the following section for ad- justing belt tension.

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