Sears 8MPL075B12B1 Exploded View of Sub-Base for Furnace only, Adapter Box, Non-Combustible Floor

Exploded View of Sub-Base for

Furnace ONLY

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Combustible

FloorBase

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Subbase Furnac_

Insulation

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Wood Screw

Sub-base for Combustible Floors - Downflow Coil

Adapter Box

The subbase for combustible floors is required when a downflow

furnace, used with a downflowcoilbox,is set on combustible flooring.

1, Cut the opening in the floor according to the dimensions in Table 5 because the base is equipped with locating tabs that center the base over the opening.

The opening in the base is 11/4 "shorter and 11/8 " narrower

than the minimum required size of the opening in the floor. This is done to maintain a 1" clearance between the floor and

the plenum.

2.Fabricate the plenum to the dimensions given in Table 5. Note that the dimensions given are outside dimensions.

3.Set the base over the opening in the floor, centering the open- ing in the base over the opening in the floor. Fasten the base

to the floor with screws or nails. See Figure 29 and Figure 30.

Drop the plenum through the opening in the base. The flange of the plenum should rest on top of the combustible floor base.

Exploded View of Base for

Downflow Cased Coil

Combustible

Floor Base

25-21-46b

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Setting the Base

Subbase '_ /

Insulation II

WoodFloor

Plenum

25-20-46A

Consideration must be given to the height of the base to allow for

easy installation of the condensate drain. See Figure 31. This

subbase for combustible floors has been designed so that the height of the subbase raises the downflow coil off the floor to allow

easy installation of the condensate drain

Condensate Line Raised by Base

25-20-52

Non-Combustible Floor

Set the furnace over the opening in the floor. If necessary, grout around the base to seal air leaks between the base and the floor.

Duct Connections

In the downflow position, the return-air duct must be connected to only the top of the furnace. Top return connections can be made by removing the knockout panel in the furnace base. Return air con- nection through the side(s) or back of the furnace is NOT allowed.

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