27
441 01 2611 06
Exploded View of Sub--Base for
Furnace ONLY
Figure 27
T
S
Plenum
J
K
H
R
L
P
1²
²²
²
2²
²²
²
Combustible
Floor Base
N
Hole in Floor
M
Setting the Base
Figure 28
Subbase
Insulation
Wood Screw Plenum
Furnace
Wood Floor
Sub--base for Combustible Floors -- Downflow Coil
Adapter Box
The s ubbase for combustible floors is required when a downflow
furnace, used with a downflow coil box, is set on combustible
flooring.
1. Cut the opening in the floor according to the dimensions in
Table 5 because thebase is equipped withlocating tabs that
center the base over the opening.
The opening in the base is 1
1
/
4
²shorter and 1
1
/
8
² narrower
than the minimum required size of the opening in the floor.
Thisisdoneto maintaina1”clearancebetweenthefloorand
the plenum.
2. Fabricate the plenum to the dimensions given in Table 5.
Note that the dimensions given are outside dimensions.
3. Setthebaseovertheopeninginthefloor,centeringtheopen-
inginthebase over the openingin the floor. Fastenthebase
to the floor with screws or nails. See Figure 29 and
Figure 30.
4. Droptheplenumthrough theopeninginthebase. Theflange
oftheplenumshouldrestontopofthecombustiblefloorbase.
Exploded View of Sub--Base for
Downflow Cased Coil
Figure 29
T
S
Plenum
J
K
H
R
L
P
1²
²²
²
2²
²²
²
Combustible
Floor Base
N
Hole in Floor
M
Setting the Base
Subbase
Insulation
Figure 30
Wood Screw Plenum
Coil Box
Wood Floor
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
heightofthesubbaseraisesthedownflowcoiloffthefloortoallow
easy installation of the c ondensate drain.
Condensate Line Raised by Base
Figure 31
25--20--52
Non--Combustible Floor
Set the furnace over the opening in the floor. If necessary, grout
around the base to seal airleaks between the baseand the floor.
Duct Connections
Inthedownflowposition,thereturn--airductmustbeconnectedto
onlythetopofthefurnace. Topreturnconnectionscanbemadeby
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