Clearances to Horizontal
Vent Terminal
Structure
Minimum Clearances for Vent
Terminal Location (all directions
unless specified)
Forced air inlet within 10 ft (3.1M)*
3 ft (0.9M) above
Combustion air inlet of another appliance
6 ft (1.8M)
Door, window, or gravity air inlet (any building opening)
4 ft (1.2M) horizontally
4 ft (1.2M) below
1 ft (305mm) above
Electric meter, gas meter ** and relief equipment
U.S. - 4 ft (1.2M) horizontally
Canada - 6 ft (1.8M)
Gas regulator **
3 ft (0.9M) horizontally
Adjoining building or parapet
6 ft (1.8M)
Adjacent public walkways
7 ft (2.1M) above
Grade (ground level)
3 ft (0.9M) above***
*Does not apply to the inlet of a direct vent appliance. **Do not terminate the vent directly above
a gas meter or service regulator. *** Consider local snow depth conditions. The vent must be at
least 6” (152mm) higher than anticipated snow depth.
2. Install the vent pipe and combustion air pipe runs (from the heater
to near the location selected through the wall).
Use the type of pipe specified in Paragraph 7.2.1.1, page 13.
Comply with the requirements in Paragraph 7.2.1.2 and 7.2.1.3, pages
14-15, when attaching pipes to the heater and installing the condensate
drain connection in the vent.
Overall vent length must comply with the table in Paragraph 7.2.1.4,
page 16.
Make all joints according to the instructions in Paragraph 7.2.1.6, page
16. Extend the runs close to the wall location selected in Step 1 above.
Provide 1/4” per foot (6mm per 305mm) downward pitch of the vent
pipe toward the heater for condensate to drain (
NOTE
: The vent pipe
will extend through the wall after the concentric adapter box is installed.
The indoor combustion air pipe will end at the concentric adapter box.)
Support pipes as required in Paragraph 7.2.1.7, page 17.
3. Prepare a 9” diameter clearance hole through the outside wall for
the 8” diameter combustion air pipe
.
Outside wall construction thickness should be 1” (25mm) minimum and 48”
(1219mm) maximum. Position the box against the wall. Being sure that the
location and box orientation are correct, mark the location where the com
-
bustion air pipe will extend through the wall. Cut a 9” diameter hole so that
the 8” pipe will be centered through the 9” opening.
4. Prepare the concentric adapter box.
4a) Determine the length of the 8” diameter combustion air pipe and
attach it to the box.
Comply with the requirements in
FIGURE 16
. Determine the length of the
pipe by measuring the wall thickness,
plus
4 to 16” (102-406 mm) beyond
the wall,
minus
the width of the pipe crimp which will be cut off.
•
•
•
•
•
So that the 8” inlet air guard will fit properly, cut the crimp off the end of the
combustion air pipe. Turn the combustion air pipe so that the seam will be
toward the top side of the box and slide it on the collar. Attach the combus
-
tion air pipe to the collar with sheetmetal screws. Seal the joint and seam
with sealant or tape.
Form I-UEAS, P/N 221232 R6, Page 21
