035-19624-001 Rev. A (0104)
Unitary Products Group
5
If a matching cooling coil is used, it may be placed directly on the fur-
nace outlet and sealed to prevent leakage. Follow the coil instructions
for installing the supply plenum. On all installations without a coil, a
removable access panel is recommended in the outlet duct such that
smoke or reflected light would be observable inside the casing to indi-
cate the presence of leaks in the heat exchanger. This access cover
shall be attached in such a manner as to prevent leaks.
RESIDENTIAL AND NON HUD MODULAR HOME
RETURN PLENUM CONNECTION
Return air may enter the furnace through the side(s) or bottom depend-
ing on the type of application. Return air may not be connected into the
rear panel of the unit. In order to achieve the airflow indicated, it is rec-
ommended those applications over 1800 CFM (57 m³/min) use return
air from two sides, one side and the bottom or bottom only. For single
return application, see data and notes on blower performance data
tables in this manual.
The return duct may be attached to the furnace by S-cleat, bend tabs or
other approved methods. Be sure to seal the duct to the furnace to pre-
vent air leakage.
The furnace must have a return duct system and the return duct system
must terminate outside the area containing the furnace.
BOTTOM RETURN AND ATTIC INSTALLATIONS
Bottom return applications normally pull return air through a base plat-
form or return air plenum. Be sure the return platform structure or return
air plenum is suitable to support the weight of the furnace.
The furnace base is equipped with a rectangular perforated panel that
can be removed by performing the following steps:
1.
Lay the furnace on its back.
2.
Push the panel out from inside the blower compartment.
3.
Bend the 3/4” flanges that will be used to attach the return air ple-
num using the scribe marks in the furnace base. Refer to Figure 1
“Bottom Image Return End” and Figure 2 for flange locations.
4.
Be sure to seal the furnace to plenum connections to prevent air
leakage. Refer to Figure 1 for unit and plenum dimensions.
Attic installations must meet all minimum clearances to combustibles
and have floor support with required service accessibility.
IMPORTANT:
if an external mounted filter rack is being used see the
instructions provided with that accessory for proper hole cut size.
The supply air temperature MUST NEVER exceed the Maximum
Supply Air Temperature, specified on the nameplate.
Operating the furnace above the maximum supply air temperature
will cause the heat exchanger to overheat, causing premature heat
exchanger failure. Improper duct sizing, dirty air filters, incorrect
manifold pressure, incorrect gas orifice and a faulty limit switch can
cause the furnace to operate above the maximum supply air tem-
perature. Refer to sections II, III and IX for additional information on
correcting the problem.
FIGURE 1:
Dimensions
20
6-3/8
1-1/4
2-3/4
6-1/8
B
A
28-1/2
6-7/8
9-7/8
20-5/8
1-3/4
14-1/2
22-3/4
B
20
A
C
28-1/2
23
3/4
6
1-3/4
4-1/8
3-1/8
8-7/8
45
T’STAT
WIRING
7/8” K.O.
3/4”
FLANGE
TOP IMAGE
SUPPLY END
BOTTOM IMAGE
RETURN END
CONDENSATE
DRAIN
OPTIONAL SIDE
RETURN CUT-OUT
WITH K.O.
REMOVED
BTUH (kW)
High / Low Fire Inpu
BTUH (kW)
High / Low Fire Output CFM (m
3
/min)
Cabinet
Size
Cabinet Dimension
Air Intake
A
A (cm)
B
B (cm)
C
C (cm)
D
D (cm)
60/39 (17.6/11.4)
55/36 (16.1/11.4)
1200 (33.98)
B
17-1/2
44.4
16-1/4
41.3
13-1/8
33.3
7-1/2
19.1
80/52 (23.4/15.2)
75/48 (21.9/14.1)
1600 (45.31)
C
21
53.3
19-3/4
50.1
16-1/2
41.9
9-1/4
23.5
100/65 (29.3/19.1)
95/60 (27.8/17.6)
2000 (56.63)
C
21
53.3
19-3/4
50.1
16-1/2
41.9
9-1/4
23.5
120/78 (35.1/22.9)
112/72 (32.8/21.1)
2000 (56.63)
D
24-1/2
62.2
23-1/8
58.7
20-1/8
51.1
10-7/8
27.6
GAS PIPE ENTRY
1-1/4 X 2-1/2
(ALL GAS PIPE
ARE 1/2” NPT)
CONNECTIONS
7/8 JUNCTION
BOX HOLE
LEFT SIDE
FRONT
RIGHT SIDE
FRONT
FRONT
(EITHER SIDE)
FIGURE 2:
Furnace Base Rectangular Perforated Panel
There are 8 Tabs to be cut
along this seam around the
rectangular panel.
Removable rectangular
base panel.
Scribe marks in base panel.
Bend sheet metal down on
these marks to form the 3/4”
flanges.
