508144-01
Page 10 of 42
Issue 2128
Figure 10. Optional Return Air Base
(Upflow Applications Only - For Use with A, B, C and D Cabinets)
FRONT VIEW
1
Unit side return air
Opening
SIDE VIEW
3−1/4
(83)
1
23 (584)
Overall
(Maximum)
(584)
23
3/4
(19)
1
22−7/16
(570)
Overall
(Maximum)
SIDE RETURN
AIR OPENINGS
(Either Side)
5−5/8
(143)
1
Minimum
11 (279)
2
Maximum
14 (356)
(683)
26−7/8
7−1/4
(184)
FURNACE
FRONT
AIR FLOW
IF BASE
IS USED
WITHOUT
IAQ CABINET,
A SINGLE
RETURN AIR
PLENUM
MUST
COVER BOTH
UNIT AND
RETURN
AIR BASE
OPENINGS
INDOOR AIR
QUALITY
CABINET
AIR BASE
OPTIONAL
RETURN
17-1/2 (446) B Width (68W62)
21 (533) C Width (68W63)
24-1/2 (622) D Width (68W64)
14-1/2 (368) A Width (65W75)
NOTE:
Optional Side Return Air Filter Kits are not for use with Return Air Base.
1
Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in. (584 x 279 mm).
The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air opening.
The size of the opening must not extend beyond the markings on the furnace cabinet.
² To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.
Horizontal Applications
The furnace can be installed in horizontal applications.
Order horizontal suspension kit (51W10) from Allied Air, or
use equivalent suspension method.
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or
alcove installations are shown in Figure 13.
This furnace may be installed in either an attic or a crawl
space. Either suspend the furnace from roof rafters or floor
joists, as shown in Figure 12, or install the furnace on a
platform, as shown in Figure 14.
Figure 12. Typical Horizontal Application Unit
Suspended in Attic or Crawl Space
Bracket
Bottom Cap
Metal Strap
3/16 inch
Air Flow
Removing the Bottom Panel
Remove the two screws that secure the bottom cap to the
furnace. Pivot the bottom cap down to release the bottom
panel. Once the bottom panel has been removed, reinstall
the bottom cap. See Figure 11.
Figure 11. Removing the Bottom Panel