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Exhaust and intake exits must be in same pressure
zone. Do not exit one through the roof and one on the
side. Also, do not exit the intake on one side and the
exhaust on another side of the house or structure.
4 − Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to il
lustrations). Maximum separation is 3" (76mm) on
roof terminations and 6" (152mm) on side wall ter
minations.
5 − Exhaust piping must terminate straight out or up as
shown. In rooftop applications, a 2" X 1−1/2" reducer for
2" venting, 3" x 2" reducer for 3" venting must be used
on the exhaust piping after it exits the structure to im
prove the velocity of exhaust away from the intake pip
ing.
On roof terminations, the intake piping should termi
nate straight down using two 90
elbows (See figure
21).
FIGURE 21
ROOF TERMINATION KIT
(15F75) LB−49107CC for 2 (51) Venting
(44J41) LB−65678A for 3 (76) Venting
UNCONDITIONED
ATTIC SPACE
1/2 (13) FOAM
INSULATION IN
UNCONDITIONED
SPACE
3 x 2 (76 x 51) OR
2 x 1−1/2 (51 x 38)
PVC REDUCER
3(76) MAX.
12 (305) ABOVE
AVERAGE SNOW
ACCUMULATION
3 (76) OR
2 (51) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
8 (203) MIN
Inches(mm)
IMPORTANT
Do not use screens or perforated metal in intake
and exhaust terminations. Doing so will cause
freeze−ups and may block the terminations.
NOTE − If winter design temperature is below 32
F (0
C), ex
haust piping must be insulated with 1/2" (13mm), Armaflex or
equivalent when run through unheated space. Do not leave
any surface area of exhaust pipe open to outside air; exterior
exhaust pipe must be insulated with 1/2" (13mm) Armaflex or
equivalent. In extreme cold climate areas, 3/4" (19mm) Arma
flex or equivalent is recommended. Insulation on outside runs
of exhaust pipe must be painted or wrapped to protect insula
tion from deterioration.
NOTE − During extremely cold temperatures, below
approximately 20
F (6.67
C), units with long runs of vent
pipe through unconditioned space, even when insulated,
may form ice in the exhaust termination that prevents the
unit from operating properly. Longer run times of at least 5
minutes will alleviate most icing problems. Also, a heating
cable may be installed on exhaust piping and termination to
prevent freeze−ups. Heating cable installation kit is avail
able from Lennox. See Condensate Piping section for part
numbers.
NOTE − Care must be taken to avoid re−circulation of ex
haust back into intake pipe.
6 − On field supplied terminations for side wall exits, ex
haust piping should extend a minimum of 12" (305mm)
beyond the outside wall. Intake piping should be as
short as possible. See figure 22.
FIGURE 22
1/2 (13) ARMAFLEX
INSULATION IN
UNCONDITIONED SPACE
2 (51) PVC
1−1/2 (38) PVC
12 (305) MIN.
2 X 1−1/2
(51 x 38)
PVC REDUCER
1/2 (13) ARMAFLEX
INSULATION
6 (152)
MAXIMUM
2 (51) PVC
COUPLING
8 (203)
MINIMUM
OUTSIDE
WALL
Inches (mm)
TOP VIEW
WALL RING KIT
(15J74) LB−49107CB for 2 (50.8) Venting
7 − On field supplied terminations, a minimum separation
distance between the end of the exhaust pipe and the
end of the intake pipe is 8" (203mm).
8 − If intake and exhaust piping must be run up a side wall
to position above snow accumulation or other obstruc
tions, piping must be supported every 3 ft. (.91m) as
shown in figure 28. Refer to figures 26 and 27 for prop
er piping method. WTK wall termination kit must be ex
tended for use in this application. See figure 31 or use
kit WTKX shown in figure 32. When exhaust and in
take piping must be run up an outside wall, the exhaust
piping is reduced to 1−1/2" (38mm) after the final el
bow. The intake piping may be equipped with a 90
el
bow turndown. Using turndown will add 5ft. (1.5m) to
the equivalent length of the pipe.