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.
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openings in doors or floors having free area of at least 2 
in.2/1,000 BTUh (4,400 mm2/kW) of total input rating of all gas 
appliances.
2. An  attic  or  crawlspace  may  be  considered  a  space  that  freely
communicates  with  the  outdoors  provided  there  are  adequate
permanent  ventilation  openings  directly  to  outdoors  having  free
area of at least 1-in.2/4,000 BTUh of total input rating for all gas
appliances in the space.
3. In spaces that use the Indoor Combustion Air Method, infiltration
should  be  adequate  to  provide  air  for  combustion,  permanent
ventilation and  dilution of flue  gases.  However, in  buildings with
unusually  tight  construction,  additional  air  MUST  be  provided
using  the  methods  described  in  the  Outdoor  Combustion  Air
Method section. 
4. Unusually tight construction is defined as Construction with:
a. Walls and ceilings exposed to the outdoors have a continuous, 
sealed vapor barrier. Openings are gasketed or sealed and
b. Doors and openable windows are weatherstripped and
c. Other openings are caulked or sealed. These include joints 
around window and door frames, between sole plates and floors, 
between wall-ceiling joints, between wall panels, at penetrations 
for plumbing, electrical and gas lines, etc. 
Combination of Indoor and Outdoor Air
1. Indoor  openings  shall  comply  with  the  Indoor  Combustion  Air
Method below and,
2. Outdoor  openings  shall  be  located  as  required  in  the  Outdoor
Combustion Air Method mentioned previously and,
3. Outdoor openings shall be sized as follows:
a. Calculate the Ratio of all Indoor Space volume divided by 
required volume for Indoor Combustion Air Method below.
b. Outdoor opening size reduction Factor is 1 minus the Ratio in a. 
above.
c. Minimum size of Outdoor openings shall be the size required in 
Outdoor Combustion Air Method above multiplied by reduction 
Factor in b. above. The minimum dimension of air openings shall 
be not less than 3 in. (80 mm). 
CONDENSATE TRAP 
Condensate Trap - Upflow Orientation
When the furnace is installed in the upflow position, it is not necessary
to relocate the condensate trap or associated tubing. Refer to Fig. 8 for
upflow condensate trap information. Refer to Condensate Drain section
for information how to install the condensate drain.
A11307
Fig. 8 – Upflow Trap Configuration
(Appearance may vary)
Condensate Trap - Downflow Orientation.
When the furnace is installed in the downflow position, the condensate
trap will be initially located at the upper left corner of the collector box,
as  received  from  the  factory.  See  the  top  image  in  Fig. 9.  When  the
furnace  is  installed  in  the  downflow  orientation,  the  condensate  trap
must be relocated for proper condensate drainage. See the bottom image
in Fig. 9. 
A11587
Fig. 9 – Downflow Trap Configuration
(Appearance may vary)
A230046
Condensate Trap
Relief Port
Collector Box
Plugs
Pressure Switch 
Port
Condensate Trap
Outlet
Condensate Trap
Relief Port
Collector Box 
Plug
Vent Elbow
Vent Elbow Clamp
Vent Pipe Clamp
UPFLOW TRAP CONFIGURATION
1 & 2 Stage Units