PG96MSA: Installation, Start-up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
18
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. To remove bottom closure panel, see Fig. 24.
Horizontal Installation 
NOTE:  The furnace must be pitched forward as shown in Fig. 19 for
proper condensate drainage. 
The  furnace  can  be  installed  horizontally  in  an  attic  or  crawlspace  on
either the  left-hand (LH) or  right-hand  (RH)  side. The  furnace  can  be
hung  from  floor  joists,  rafters  or  trusses  or  installed  on  a
non-combustible platform, blocks, bricks or pad. 
Supply Air Connections 
For a furnace not equipped with a cooling coil, the outlet duct shall be
provided  with  a  removable  access  panel.  This  opening  shall  be
accessible when the furnace is installed and shall be of such a size that
the  heat  exchanger  can  be  viewed  for  possible  openings  using  light
assistance or a  probe  can  be  inserted for sampling  the  air stream. The
cover attachment shall prevent leaks. 
Connect  supply-air  duct  to  flanges  on  furnace  supply-air  outlet.  Bend
flange upward to 90° with wide duct pliers. See Fig. 20. The supply-air
duct  must  be  connected  to  ONLY  the  furnace  supply-outlet-air  duct
flanges or air conditioning coil casing (when used). DO NOT cut main
furnace  casing  side  to  attach  supply  air  duct,  humidifier,  or  other
accessories.  All  supply-side  accessories  MUST  be  connected  to  duct
external to furnace main casing. 
Return Air Connections 
The return-air duct may be connected to bottom of the furnace. The side
of  casing  that  faces  downward  may  also  be  used  for  return  air
connection. A combination of the bottom and downward facing side may
also be used. The upward facing side of the casing cannot be used as a
return air connection. See Fig. 23. 
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. To remove bottom closure panel, see Fig. 24.
Side Return Air Inlet 
These furnaces are shipped with bottom closure panel installed in bottom
return-air  opening. This  panel  MUST  be in place  when  side return  air
inlet(s) are used without a bottom return air inlet.
Not all horizontal furnaces are approved for side return air connections
See Fig. 23. Where required by code, seal bottom closure to furnace with
tape, mastic, or other durable sealing method.
Table 6 – Opening Dimensions - In. (mm)
FURNACE 
CASING WIDTH
IN. (mm) 
APPLICATION 
PLENUM OPENING  FLOOR OPENING 
A  B  C  D 
14–3/16
*
(360) 
*. Not all families have these models
Upflow Applications on Combustible or Noncombustible Flooring 
(subbase not required) 
12-11/16
(322) 
21-5/8
(549) 
13-5/16
(338) 
22-1/4
(565)
Downflow Applications on Noncombustible Flooring
 (subbase not required) 
12-9/16
(319) 
19
(483) 
13-3/16
(335) 
19-5/8
(498) 
Downflow applications on combustible flooring 
(subbase required) 
11-13/16
(300) 
19
(483) 
13-7/16
(341) 
20-5/8
(524) 
Downflow Applications on Combustible Flooring with coil assembly or 
coil box (subbase not required) 
12-5/16
(313) 
19
(483) 
13-5/16
(338) 
20
(508)
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
(524) 
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
(524) 
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) 
21-5/8
(549)
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
(524) 
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)