Page 9
Downflow Installation
Downflow unit installs in three ways: on non−combustible
flooring, on combustible flooring using an additive base, or
on a reverse−flow cooling cabinet. Do not drag the unit
across the floor.
Installation on Non−Combustible Flooring
1 − Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply connec-
tions, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances.
See table 1 for correct floor opening size.
2 − Flange warm air plenum and lower the plenum into the
opening.
3 − Set the unit over the plenum and seal the plenum to
the unit.
3 − Ensure that the seal is adequate.
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Model No.
Front to Rear
Side to Side
in
.
mm
in.
mm
A Cabinet (14.5")
19 − 3/4
502
13 − 1/4
337
B Cabinet (17.5")
19 − 3/4
502
16 − 1/4
413
C Cabinet (21")
19 − 3/4
502
19 − 3/4
502
D Cabinet (24.5")
19 − 3/4
502
23 − 1/4
591
NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See figure 1.
Installation on Combustible Flooring
1 − When unit is installed on a combustible floor, an addi-
tive base must be installed between the furnace and
the floor. The base must be ordered separately for the
following cabinet sizes:
D
A
cabinet
14.5"
− #
11M59
D
B
cabinet
17.5"
− #
11M60
D
C
cabinet
−
21"
#
11M61
D
D
cabinet
24.5"
− #
11M62
See table 2 for opening size to cut in floor.
CAUTION
The furnace and additive base shall not be installed
directly on carpeting, tile, or other combustible ma-
terial other than wood flooring.
The furnace and additive base shall not be installed
directly on carpeting, tile, or other combustible ma-
terial other than wood flooring.
TABLE 2
ADDITIVE BASE FLOOR OPENING SIZE
Model No.
Front to Rear
Side to Side
in.
mm
in.
mm
A Cabinet (14.5")
22
559
15 − 3/4
400
B Cabinet (17.5")
22
559
18 − 3/4
476
C Cabinet (21")
22
559
22 − 3/4
578
D Cabinet (24.5")
22
559
25 − 3/4
654
NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
unit opening. See figure 1.
2 − After opening is cut, set additive base into opening.
3 − Check fiberglass strips on additive base to make sure
they are properly glued and positioned.
4 − Lower supply air plenum into additive base until ple-
num flanges seal against fiberglass strips.
NOTE − Be careful not to damage fiberglass strips.
Check for a tight seal.
5 − Set the furnace over the plenum.
6 − Ensure that the seal between the furnace and plenum
is adequate.
G50DF(X)UNIT
SUPPLY AIR PLENUM
ADDITIVE BASE
PROPERLY
SIZED FLOOR
OPENING
FIGURE 6
Installation on Cooling Cabinet
1 − Refer to reverse−flow coil installation instructions for
correctly sized opening in floor and installation of cabi-
net.
2 − When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
