Lennox EL296DFV Installation Instructions Manual page 28

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.
NOTE - Flue gas may be slightly acidic and may adversely
affect some building materials. If any vent termination is
used and the flue gasses may impinge on the building ma­
terial, a corrosion-resistant shield (minimum 24 inches
square) should be used to protect the wall surface. If the
optional tee is used, the protective shield is recommended.
The shield should be constructed using wood, plastic,
sheet metal or other suitable material. All seams, joints,
cracks, etc. in the affected area should be sealed using an
appropriate sealant. See figure 43.
Intake and exhaust pipes may be routed either horizontally
through an outside wall or vertically through the roof. In at­
tic or closet installations, vertical termination through the
roof is preferred. Figures 35 through 42 show typical ter­
minations.
1 - Vent terminations are not required to be in the same
pressure zone. You may exit the intake on one side of
the structure and the exhaust on another side (figure
36). You may exit the exhaust out the roof and the in­
take out the side of the structure (figure 37).
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.
NOTE - When venting in different pressure zones, the
maximum separation requirement of intake and ex­
haust pipe DOES NOT apply.
3 - On roof terminations, the intake piping should termi­
nate straight down using two 90° elbows (See figure
35).
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 10.
TABLE 10
EXHAUST PIPE TERMINATION SIZE REDUCTION
EL296
MODEL
*045 and *070
*090
110
*EL296DFV-045, -070 and -090 units with the flush-mount termina­
tion must use the 1-1/2"accelerator supplied with the kit.
5 - On field-supplied terminations for side wall exit, ex­
haust piping may extend a maximum of 12 inches
(305mm) for 2" PVC and 20 inches (508mm) for 3"
(76mm) PVC beyond the outside wall. Intake piping
should be as short as possible. See figure 43.
NOTE - Care must be taken to avoid recirculation of
exhaust back into intake pipe.
Termination
Pipe Size
1-1/2" (38mm)
2" (51mm)
2" (51mm)
Page 28
6 - On field supplied terminations, a minimum distance
between the end of the exhaust pipe and the end of
the intake pipe without a termination elbow is 8" and a
minimum distance of 6" with a termination elbow. See
figure 43.
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 35
Exiting Exhaust and Intake Vent
(different pressure zone)
Exhaust
Furnace
Pipe
FIGURE 36
Exiting Exhaust and Intake Vent
(different pressure zone)
Roof T erminated
Exhaust Pipe
Furnace
FIGURE 37
SIZE TERMINATION
PIPE PER TABLE 10.
UNCONDITIONED
ATTIC SPACE
Inlet Air
(Minimum 12in.
(305 mm) Above
grade or snow
accumulation)
Inlet Air
(Minimum 12in.
(305 mm) Above
grade or snow
accumulation)