508145-01
Page 10 of 36
Issue 2128
Return Air Opening -- Downflow Units
The following steps should be taken when installing
plenum:
1. Bottom edge of plenum should be flanged with a
Figure 11.
SECURE FROM
OUTSIDE CABINET
HEMMED EDGE
PLENUM
SEALING STRIP
(Field Provided)
CABINET SIDE PANEL
Side View
2. Sealing strip should be used.
3. In all cases, plenum should be secured to top flanges
of furnace with sheet metal screws.
Figure 12.
INSIDE CABINET
HEMMED EDGE
FIBERGLASS
SEALING STRIP
(Field Provided)
CABINET SIDE
PANEL
PLENUM
Side View
SECURE FROM
4.
In closet installations, it may be impossible to install
sheet metal screws from the outside. In this case,
make plenum with a removable front and install screws
from the inside (see Figure 12).
5. Make certain that an adequate seal is made.
Cabinet
Width
Front to Rear
Side to Side
in
mm
in
mm
A (14-1/2”)
22
559
15-3/4
400
B (17-1/2”)
22
559
18-3/4
476
Table 2.
Combustible Floor Opening Size
Installation on Cooling Cabinet
1. Refer to reverse-flow coil installation instructions for
correctly sized opening in floor and installation of
cabinet.
NOTE:
Downflow combustible flooring kit is not used.
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 10.
UNIT
COOLING COIL
PLENUM
PROPERLY
SIZED FLOOR
OPENING
Figure 13.
Front
Back
Horizontal