Lennox EL297UH045XV36B Unit Information page 71

Details of Intake and Exhaust Piping Terminations for
Direct Vent Installations
NOTE - In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged to outdoors.
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 material, a corrosion-re-
sistant 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 35.
Intake and exhaust pipes may be routed either horizontal-
ly through an outside wall or vertically through the roof. In
attic or closet installations, vertical termination through the
roof is preferred. FIGURE 32 through FIGURE 40 show
typical terminations.
1 - Intake and exhaust 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 33). You may exit the
exhaust out the roof and the intake out the side of
the structure (FIGURE 34).
2 - Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to
illustrations). Maximum separation is 3" (76MM)
on roof terminations and 6" (152MM) on side wall
terminations.
NOTE - When venting in different pressure zones,
the maximum separation requirement of intake and
exhaust pipe DOES NOT apply.
3 - On roof terminations, the intake piping should
terminate straight down using two 90° elbows
(FIGURE 32).
4 - Exhaust piping must terminate straight out or up as
shown. A reducer may be required on the exhaust
piping at the point where it exits the structure to
improve the velocity of exhaust away from the
intake piping. See TABLE 25.
NOTE - Care must be taken to avoid recirculation of
exhaust back into intake pipe.
5 - On field-supplied terminations for side wall exit,
exhaust 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 35.
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 35.
7 - If intake and exhaust piping must be run up a side
wall to position above snow accumulation or other
obstructions, piping must be supported. At least
one bracket must be used within 6" from the top of
the elbow and then every 24" (610mm) as shown
in FIGURE 35, to prevent any movement in any
direction. When exhaust and intake piping must
be run up an outside wall, the exhaust piping must
be terminated with pipe sized per TABLE 25 The
intake piping may be equipped with a 90° elbow
turndown. Using turndown will add 5 feet (1.5m) to
the equivalent length of the pipe.
8 - A multiple furnace installation may use a group
of up to four terminations assembled together
horizontally, as shown in FIGURE 39.
EXHAUST PIPE TERMINATION SIZE REDUCTION
EL297UHV MODEL
*045 and 070
*090
110
135
*EL297UHV-045, -070 and -090 units with the flush mount termination
must use the 1-1/2"accelerator supplied with the kit.
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
Exiting Exhaust and Intake Vent
(different pressure zone)
Exhaust
Pipe
Exiting Exhaust and Intake Vent
(different pressure zone)
Roof T erminated
Exhaust Pipe
Page 71
TABLE 25
Termination Pipe Size
1-1/2" (38MM)
2" (51MM)
2" (51MM)
2" (51MM)
3"(76mm) MAX.
UNCONDITIONED
ATTIC SPACE
(15F75 or 44J41)
FIGURE 32
Inlet Air
Furnace
(Minimum 12 in.
305 MM) above
grade or snow
accumulation
FIGURE 33
Inlet Air
(Minimum 12 in.
Furnace
305 MM) above
grade or snow
accumulation
FIGURE 34