Lennox 97G2DFV Installation Instructions Manual page 29

Warm air gas furnace downflow air discharge direct vent & non-direct vent
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Details of Exhaust Piping Terminations for Non-
Direct Vent Applications
Exhaust pipe may be routed either horizontally through
an outside wall or vertically through the roof. In attic or
closet installations, vertical termination through the roof
is preferred. Figure 39 through Figure 42 show typical
terminations.
1.
Exhaust piping must terminate straight out or up as
shown. The termination pipe must be sized as listed
in Table 9. The specified pipe size ensures proper
velocity required to move the exhaust gases away
from the building.
2.
On field supplied terminations for side wall exit,
exhaust piping may extend a maximum of 12 inches
(305 mm) for 2" PVC and 20" (508 mm) for 3" (76 mm)
PVC beyond the outside wall. See Figure 40.
3.
If exhaust piping must be run up a sidewall to position
above snow accumulation or other obstructions, piping
must be supported every 24" (610 mm) as shown in
Figure 41. When exhaust piping must be run up an
outside wall, any reduction in exhaust pipe size must
be done after the final elbow.
12" (305MM)
ABOVE AVE.
SNOW
ACCUMULATION
3" (76MM) OR
2" (51MM) PVC
PROVIDE SUPPORT
FOR EXHAUST LINES
Figure 39. Non-Direct Vent Roof Termination Kit
FIELD-PROVIDED
REDUCER MAY BE
REQUIRED TO
ADAPT DIFFERENT
VENT PIPE SIZE TO
TERMINATION
SIZE TERMINATION
PER EXHAUST PIPE
TERMINATION SIZE
REDUCTION TABLE
Figure 40. Non-Direct Vent Field Supplied Wall
Termination
508405-01
SIZE PER EXHAUST PIPE
TERMINATION SIZE
REDUCTION TABLE
UNCONDITIONED
ATTIC SPACE
Issue 2341
FIELD-PROVIDED
REDUCER MAY BE
REQUIRED TO
ADAPT DIFFERENT
VENT PIPE SIZE TO
TERMINATION
* Use wall support every 24" (610 mm). Use two supports of extension is greater than 24"
(610 mm) but less than 48" (1219 mm).
Figure 41. Non-Direct Vent Field Supplied Wall
Termination - Extended
* SIZE TERMINATION PIPE PER EXHAUST
PIPE TERMINATION SIZE REDUCTION TABLE
Minimum 12" (305mm)
above chimney top
plate or average snow
accumulation
INTAKE PIPE
INSULATION (optional)
SHEET
METAL TOP
PLATE
INSULATE
TO FORM
SEAL
NOTE: Do not discharge exhaust gases directly into any
chimney or vent stack. If vertical discharge through an existing
unused chimney or stack is required, insert piping inside
chimney until the pipe open end is above top of chimney and
terminate as illustrated. In any exterior portion of chimney, the
exhaust vent must be insulated.
Figure 42. Non-Direct Vent Application Using Existing
Chimney
SIZE TERMINATION
PER EXHAUST PIPE
TERMINATION SIZE
REDUCTION TABLE
STRAIGHT-CUT OR
ANGLE-CUT IN DIRECTION
OF ROOF SLOPE *
EXHAUST VENT
1/2" (13mm)
WEATHERPROOF
INSULATION
SHOULDER OF FITTINGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
EXTERIOR
PORTION OF
CHIMNEY
Page 29 of 53

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