Lennox G61MPV Service Manual page 60

Details of Intake and Exhaust Piping Terminations for
Direct Vent Installations
NOTE − In Direct Vent installations, combustion air is tak-
en from outdoors and flue gases are discharged to out-
doors.
Intake and exhaust pipes 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. Figures 32 through 42 show typical termina-
tions.
1. 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.
2. 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 termina-
tions.
3. On roof terminations, the intake piping should termi-
nate straight down using two 90° elbows (See figure
32).
4. Exhaust piping must terminate straight out or up as
shown. A reducer may be required on the exhaust pip-
ing at the point where it exits the structure to improve
the velocity of exhaust away from the intake piping.
See table 38.
NOTE − Care must be taken to avoid recirculation of
exhaust back into intake pipe.
3"(76mm) MAX.
Inches(mm)
8" (203mm) MIN
12" (305mm) ABOVE
AVERAGE SNOW
ACCUMULATION
3" (76mm) OR
2" (51mm) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
DIRECT VENT ROOF TERMINATION KIT
(15F75 or 44J41)
FIGURE 32
SIZE TERMINATION
PIPE PER TABLE 38.
UNCONDITIONED
ATTIC SPACE
1/2" (13mm) FOAM
INSULATION IN
UNCONDITIONED
SPACE
Page 60
FIELD SUPPLIED WALL TERMINATION OR
(15F74) WALL RING TERMINATION KIT
NOTE − FIELD PROVIDED
REDUCER MAY BE
REQUIRED TO ADAPT
LARGER VENT PIPE SIZE
TO TERMINATION
C
A
1/2" (13mm) ARMAFLEX INSULATION
IN UNCONDITIONED SPACE
E
* WALL
SUPPORT
C
See venting table 37 for maximum venting lengths with this
arrangement.
* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219 mm).
NOTE − One wall support must be 6" (152 mm) from top of each pipe
(intake and exhaust)
2" (51mm)
Vent Pipe
A−Minimum clearance
above grade or average
12" (508MM)
snow accumulation
B−Maximum horizontal
separation between
6" (152MM)
intake and exhaust
C−Minimum from
8" (203MM)
end of exhaust to
inlet of intake
D−Maximum exhaust
12" (305MM)
pipe length
E−Maximum wall support
distance from top of each 6" (152MM)
pipe (intake/exhaust)
FIGURE 33
1/2" (13mm) ARMAFLEX
INSULATION IN UN-
CONDITIONED SPACE
SIZE TERMINATION
PER TABLE 38
D
B
STRAIGHT
APPPLICATION
D
B
A
EXTENDED
APPLICATION
3" (76mm)
Vent Pipe
12" (508MM)
6" (152MM)
8" (203MM)
20" (508MM)
6" (152MM)