PG92MSA: 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.
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A170123
Fig. 24 – Removing Bottom Closure Panel (2 Screws)
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 only side return
air is used. Where required by code, seal bottom closure to furnace with
tape, mastic or other durable sealing method.
Side return-air openings can only be used in UPFLOW
configurations. Do not use side return-air openings in
DOWNFLOW or HORIZONTAL configurations. See Fig. 22, Fig. 23, 
and Fig. 24.
Downflow Installation 
NOTE:  The  furnace  must  be  pitched  as  shown  in  Fig. 19  for  proper
condensate drainage. 
Supply Air Connections 
NOTE: For downflow applications, this furnace is approved for use on
combustible  flooring  when any  one  of  the  following  three  accessories
are used: 
• Manufacturer’s approved downflow combustible floor subbase
• Manufacturer’s approved cased evaporator coil
• Manufacturer’s approved evaporator coil casing
1. Determine application being installed from Table 6.
2. Construct hole in floor per Table 6 and Fig. 25.
3. Construct plenum to dimensions specified in Table 6 and Fig. 25.
4. If  downflow  subbase  is  used,  install  as  shown.  If  manufacturer’s
cased  evaporator  coil  or  coil  casing  is  used,  install  as  shown  in
Fig. 25. 
NOTE: It is recommended that the perforated supply-air duct flanges be
completely  removed  from  furnace  when  installing  the  furnace  on  a
factory-supplied cased  coil  or coil  box. To  remove  the supply-air  duct
flange,  use  wide  duct pliers  or  hand  seamers  to  bend  flange back and
forth until it breaks off. Be careful of sharp edges. See Fig. 20. 
Connect  supply-air  duct  to  supply-air  outlet  on  furnace.  Bend  flange
inward past 90° with  wide duct pliers See Fig. 20. The supply-air duct
must be connected to ONLY the furnace supply outlet or air conditioning
coil  casing  (when  used).  When  installed  on  combustible  material,
supply-air  duct  must  be  connected  to  ONLY  the  factory-approved
accessory  subbase,  or  a  factory-approved  air  conditioning  coil  casing.
DO  NOT  cut  main  furnace  casing  to  attach  supply  side  air  duct,
humidifier, or other accessories. All supply-side accessories  MUST be
connected to duct external to furnace casing. 
Return Air Connections 
The  return-air  duct  must  be  connected  to  return-air  opening  (bottom
inlet). DO NOT cut into casing sides (left or right). Bypass humidifier
connections should be made at ductwork or coil casing sides exterior to
furnace. See Fig. 22.
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
CAUTION
!
EQUIPMENT OR PROPERTY DAMAGE
Failure  to  follow  this  caution  could  result  in  equipment  or  property
damage
When furnace is installed in a downflow application, make sure water
lines and other sources of water cannot drip or fail in such a way that
water  can  collect  on  the  blower  motor,  wiring,  and  furnace  control
board.
CAUTION
!
CUT HAZARD
Failure to follow this caution may result in personal injury. 
Sheet  metal  parts may have  sharp  edges or  burrs.  Use  care and wear
appropriate  protective  clothing,  safety  glasses  and  gloves  when
handling parts, and servicing furnaces. 
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. 
WARNING
!
FIRE, EXPLOSION, AND CARBON MONOXIDE 
POISONING HAZARD
Failure to follow this warning could result in personal injury, death, or
property damage.
Do  not  install  the  furnace  on  its  back  or  hang  furnace  with  control
compartment  facing  downward.  Safety  control  operation  will  be
adversely  affected.  Never  connect  return-air  ducts  to  the  back  of  the
furnace.
CAUTION
!
MINOR PROPERTY HAZARD
Failure to follow this caution may result in minor property damage.
Local  codes  may  require  a  drain  pan  under  entire  furnace  and
condensate  trap  when  a  condensing  furnace  is  used  in  an  attic
application or over a finished ceiling.