9
Blower Installation:
1.
Turn off all electrical supply circuits to the
furnace at the main service panel.
2.
Remove furnace front door and switch fur-
nace circuit breaker(s) to “OFF”.
3.
Disconnect the motor plug from the control
panel receptacle.
4.
Remove one screw from left side of blower
and three screws from right side of blower;
slide blower forward and remove.
5.
Install new blower ensuring the side flanges
engage under side mounting tabs (three on
one side, one on the other) and the long tab
in the rear.
6.
Replace screws previously removed from
blower.
7.
Switch circuit breaker(s) to “ON”, reinstall
furnace front door, and turn on electrical
supply circuits to the furnace.
Optional Plenum Connectors for
Downflow Systems
Plenum connectors are recommended for heated
air distribution in under-the-floor duct systems.
With this system, furnaces may be installed on
combustible flooring without a separate sub-
base. Also, the furnace rear mounting plate
(see Figure 3) supplied with the plenum connec-
tors is recommended for use with this type of
installation.
SELECTING PLENUM CONNECTOR
1.
Determine depth of floor cavity from sur-
face of floor to top of supply air duct (see
Figure 4).
2.
Select appropriate model from Table 4
which matches X-dimension of floor cavity.
To maximize air delivery, remove reducer
(C in Figure 4) to obtain largest open area
that will fit duct/floor construction.
NOTE: Plenum connectors may be
installed in any one of four positions.
TYPICAL INSTALLATION OF
DOWNFLOW SYSTEMS
The following steps describe installation in-
structions for an under-the-floor supply duct
system with a return air system that can be
either non-ducted or ducted. Plenum connec-
tors (Table 4) are recommended for this applica-
tion.
NOTE: Before installing this furnace, consider
all clearances for the installation and future
servicing of the furnace. Refer to Table 1.
Return Air and Filtering Systems
Furnaces may be installed with non-ducted or
ducted return air. For non-ducted return air
systems, either the optional grille and frame
assembly or the optional wall mount grille is
recommended. For ducted return air systems
with air conditioners or heat pumps, either pro-
viding an access panel in the duct or using the
A
B
19”
(483 mm)
19"
(483 mm)
TOP VIEW
X
Reducer
Felt Seal
Corner
Spacers
C
OPENING TO DUCT
A= 13-1/4" (337 mm)
B= 10-3/4" (274 mm)
WITH PLATE (C) REMOVED
OPENING BECOMES
13-1/4” x 13-1/4”
Figure 4. Plenum Connector Selection
x
SUPPLY AIR DUCT
FLOOR CAVITY
If “X”
Use Plenum
floor cavity is:
Connector Model
English
Metric (mm)
Order No.
7/8"
22
901987
2"
51
901988
4 1/4"
108
901989
6 1/4"
159
901990
8 1/4"
210
901991
10 1/4"
260
901992
12 1/4"
311
901993
Table 4. Floor Cavity Sizes