20
440 01 4201 03
Specifications subject to change without notice.
humidifier, or other accessories. All supply
−
side accessories
MUST be connected to duct external to furnace casing.
Return Air Connections
!
WARNING
FIRE HAZARD
A failure to follow this warning could cause personal injury,
death and/or property damage.
Never connect return
−
air ducts to the back of the furnace.
Follow instructions below.
The return
−
air duct must be connected to return
−
air opening
(bottom inlet) as shown in
sides (left or right). Bypass humidifier connections should be
made at ductwork or coil casing sides exterior to furnace. (See
)
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel installed
in bottom return
−
air opening. Remove and discard this panel
when bottom return air is used in downflow applications. To
remove bottom closure panel, perform the following:
1. Tilt or raise furnace and remove four (4) screws holding
bottom plate panel. (See
2. Remove bottom plate.
3. Remove bottom closure panel.
4. Reinstall bottom plate and screws.
Figure 22
Duct Flanges
A10493
UPFLOW
DOWNFLOW
HORIZONTAL
YES
NO
NO
YES
YES
YES
NO
120
°
MIN
YES
120
°
MIN
YES
120
°
MIN
90
°
90
°
PERFORATED
DISCHARGE DUCT
FLANGE
Table 5
Opening Dimensions
−
in. (mm)
FURNACE
CASING WIDTH
IN. (mm)
APPLICATION
PLENUM OPENING
FLOOR OPENING
A
B
C
D
17–1/2
(445)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
16
(406)
21
−
5/8
(549)
16
−
5/8
(422)
22
−
1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
15
−
7/8
(403)
19
(483)
16
−
1/2
(419)
19
−
5/8
(498)
Downflow applications on combustible flooring (subbase required)
15
−
1/8
(384)
19
(483)
16
−
3/4
(425)
20
−
5/8
(600)
Downflow Applications on Combustible Flooring with Coil Assembly or coil
box (subbase not required)
15
−
1/2
(394)
19
(483)
16
−
1/2
(419)
20
(508)
21
(533)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
19
−
1/2
(495)
21
−
5/8
(549)
20
−
1/8
(511)
22
−
1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
19
−
3/8
(492)
19
(483)
20
(508)
19
−
5/8
(498)
Downflow applications on combustible flooring
(subbase required)
18
−
5/8
(473)
19
(483)
20
−
1/4
(514)
20
−
5/8
(600)
Downflow Applications on Combustible Flooring with Coil Assembly or coil
box (subbase not required)
19
(483)
19
(483)
20
(508)
20
(508)
24
−
1/2
(622)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
23
(584)
21
−
1/8
(537)
23
−
5/8
(600)
22
−
1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
22
−
7/8
(581)
19
(483)
23
−
1/2
(597)
19
−
5/8
(498)
Downflow applications on Combustible flooring
(subbase required)
22
−
1/8
(562)
19
(483)
23
−
3/4
(603)
20
−
5/8
(600)
Downflow Applications on Combustible Flooring with Coil Assembly or
coil box (subbase not required)
22
−
1/2
(572)
19
(483)
23
−
1/2
(597)
20
(508)