507867-02
Page 11 of 54
Issue 2128
Figure 13.
Upflow Applications
Installation Clearances
Top
Right Side
Left Side
Bottom (floor)
Top/Plenum
1 in. (25 mm)
*Front
0
Back
0
Sides
0†
Vent
0
Floor
0‡
* Front clearance in alcove installation must be 24 in. (610
mm). Maintain a minimum of 24 in. (610 mm) for front service
access.
† Allow proper clearances to accommodate condensate trap.
‡ For installations on a combustible floor, do not install
the furnace directly on carpeting, tile or other combustible
materials other than wood flooring.
Furnace applications which include side return air and a
condensate trap installed on the same side of the cabinet
(trap can be installed remotely within 5 ft.) require either a
return air base or field-fabricated transition to accommodate
an optional IAQ accessory taller than 14.5”. See Figure 14.
Figure 14. Side Return Air
(with Transition and Filter)
NOTE:
C20 (5 Ton) size units installed in upflow
applications that require air volumes of 1800 cfm (850 L/s)
or greater must have one of the following:
•
Single side return air with transition, to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter.
(Required to maintain proper air velocity.)
•
Single side return air with optional “RAB”
R
eturn
A
ir
B
ase.
•
Bottom return air.
•
Return air from both sides.
•
Bottom and one side return air.
FRONT VIEW
SIDE VIEW
1
Unit side return air
Opening
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)
CONDENSATE
TRAP
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 of air and over (W x H): 23 x 11 in. (584 x279 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.
Figure 15.
Optional Return Air Base (Upflow Applications Only)
