Page 11
Removing the Bottom Panel
FIGURE 10
Screw
Bottom Panel
Bottom Cap
Optional Return Air Base
(Upflow Applications Only −− For use with B, C and D cabinets only)
FIGURE 11
NOTE− Optional Side Return Air Filter Kits are not for use with RAB 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.
NOTE− Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.
1
Unit side return air
Opening
FRONT VIEW
SIDE VIEW
27−5/8 (702)
4
(102)
1
23 (584)
Overall
(Maximum)
OPTIONAL RAB
RETURN AIR BASE
23 (584)
7−1/4 (184)
7/8
(22)
3/4
(19)
1
22−7−16
(570)
Overall
(Maximum)
SIDE RETURN
AIR OPENINGS
(Either Side)
FURNACE
FRONT
14
(356)
AIR FLOW
5−5/8
(143)
1
Minimum
11 (279)
2
Maximum
14 (356)
21 (533) RAB−C (98M58)
24−1/2 (622) RAB−D (98M59)
17−1/2 (446) RAB−B (98M60)