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FIGURE 28
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
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 mate
rial, a corrosion-resistant shield (minimum 24 inches
square) should be used to protect the wall surface. If the op
tional 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 appropri
ate sealant. See figure 32.
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 29 through 36 show typical termina
tions.
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 30). You may exit the exhaust out the roof
and the intake out the side of the structure (figure 31).
2. Intake and exhaust pipes should be placed as close to
gether as possible at termination end (refer to illustra
tions). Maximum separation is 3” (76mm) on roof ter
minations and 6” (152mm) on side wall terminations.
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
29).
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 27.
NOTE
- Care must be taken to avoid recirculation of ex
haust back into intake pipe.
TABLE 27
EXHAUST PIPE TERMINATION SIZE REDUCTION
SLP98DFV
MODEL
Exhaust Pipe Size
Termination Pipe Size
*070
2”, 2-1/2” or 3”
1-1/2”
*090
2”, 2-1/2” or 3”
2”
110
2”, 2-1/2” or 3”
2”
*SLP98DF -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 32.
