COMFORT-AIRE GDD80A, Installation Instructions Manual

Page: 11 / 36

507712-01 Page 11 of 36 Issue 1642
Table 2. Combustible Flooring Base Opening Size
Cabinet
Width
Catalog
Number
Front to
Rear
Side to Side
in. mm in. mm
B Cabinet
(17.5”)
11M60 22 559 18-3/4 476
C Cabinet
(21”)
11M61 22 559 22-3/4 578
Figure 12
2. After opening is cut, set the combustible flooring base
into opening.
3. Check fiberglass strips on the combustible flooring
base to make sure they are properly glued and
positioned.
4. Lower supply air plenum into the combustible flooring
base until plenum 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.
Installation on Cooling Coil Cabinet
See Figure 13
NOTE : Downflow combustible flooring kit is not used.
1. Refer to reverse flow coil installation instructions for
correctly sized opening in floor and installation of
cabinet.
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.
Figure 13
Return Air Opening - Downflow Units
Return air may be brought in only through the top opening of
a furnace installed in the downflow position. The following
steps should be taken when installing plenum:
1. Bottom edge of plenum should be flanged with a
hemmed edge (See Figure 14 or 15).
2. Sealing strips should be used to ensure an airtight
seal between the cabinet and the plenum.
3. In all cases, plenum should be secured to top of
furnace using sheet metal screws.
4. Make certain that an adequate seal is made.
Figure 14
Figure 15