292278-UIM-A-0108
6
Unitary Products Group
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 stay within the velocity rating of the fil-
ter(s), it is recommended that 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 perfor-
mance data tables in this manual.
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 blockoff panel that can
be removed by performing the following steps:
1.
Lay the furnace on its back.
2.
Remove the screws from the toe plate and remove the toe plate.
3.
Pull the base plate out of the furnace and re-install the toe plate.
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:
When an external mounted filter rack is being used see
the instructions provided with that accessory for proper hole cut size.
SECTION IV: FILTERS
FILTER INSTALLATION
All applications require the use of a filter. Replacement filter size is
shown in Table 4.
Filters must be installed external to the furnace cabinet.
DO NOT
attempt to install filters inside the furnace.
NOTES:
1. Air velocity through throwaway type filters may not exceed 300 feet
per minute. All velocities over this require the use of high velocity fil-
ters.
2. Air flows above 1800 CFM require either return from two sides or
one side plus bottom.
SIDE RETURN - FILTER INSTALLATION
Locate and mark the side return opening. Refer to Figure 1 for dimen-
sions of the cutout.
Install the side filter rack following the instructions provided with that
accessory. If a filter(s) is provided at another location in the return air
system, the ductwork may be directly attached to the furnace side
panel.If not provided with the furnace, an accessory filter rack is avail-
able for mounting the filter external to the cabinet.
FIGURE 1:
Dimensions
30-7/8
21-1/2
13-7/8
7
11
7/8
23-3/4
7/8
30-1/8
26-1/2
24-5/8
A
40
26-1/2
25-3/8
28-3/8
21-1/2
11
8
1-1/2” GAS
PIPE ENTRY
7/8” JUNCTION
BOX HOLE
T-STAT WIRING
7/8” K.O.
CONDENSATE
DRAIN 7/8” K.O.
OPTIONAL RETURN AIR
CUT-OUT (either side)
FOR USE WITH
EXTERNAL FILTER
FRAME
LEFT SIDE
FRONT
RIGHT SIDE
26-3/4
1-3/8
1-1/4
C
24-3/8
20
5/8
5/8
B
24-17/16
2
D
BOTTOM IMAGE
RETURN END
TOP IMAGE
SUPPLY END
1-1/2” GAS
PIPE ENTRY
7/8” JUNCTION
BOX HOLE
T-STAT WIRING
7/8” K.O.
CONDENSATE
DRAIN 7/8” K.O.
BTUH (kW)
Input
CFM
(m
3
/min)
Cabinet
Size
Cabinet Dimension
A (in.)
A (cm)
B (in.)
B (cm)
C (in.)
C (cm)
D (in.)
D (cm)
60 (17.6)
1200 (34.0)
B
17-1/2
44.4
16-1/4
41.3
14-1/2
36.8
8-1/2
21.6
80 (23.4)
1200 (34.0)
B
17-1/2
44.4
16-1/4
41.3
11
36.8
8-1/2
21.6
80 (23.4)
1600 (45.3)
C
21
53.3
19-3/4
50.2
18
45.7
8-7/8
22.5
100 (29.3)
1600 (45.3)
C
21
53.3
19-3/4
50.2
18
45.7
8-7/8
22.5
100 (29.3)
2000 (56.6)
C
21
53.3
19-3/4
50.2
18
45.7
8-7/8
22.5
120 (35.2)
2000 (56.6)
D
24-1/2
62.2
23-1/4
59.4
21-1/2
54.6
10-5/8
27.0
TABLE 4:
Recommended Filter Sizes
Input
BTU/H (kW)
CFM
(m
3
/min)
Cabinet
Size
Side Return
Filter in. (cm)
Bottom Return
Filter in. (cm)
60 (17.8)
1200 (34.0)
B
16 x 25 (41 x 64) 16 x 25 (41 x 64)
80 (23.4)
1200 (34.0)
B
16 x 25 (41 x 64) 16 x 25 (41 x 64)
80 (23.4)
1600 (45.3)
C
16 x 25 (41 x 64) 20 x 25 (51 x 64)
100 (29.3) 1600 (45.3)
C
16 x 25 (41 x 64) 20 x 25 (51 x 64)
100 (29.3) 2000 (56.6)
C
16 x 25 (41 x 64) 20 x 25 (51 x 64)
120 (35.1) 2000 (56.6)
D
(2) 16 x 25
(2) (41 x 64)
22 x 25 (56 x 64)
