13
Viii. coMBUstioN air aND VeNt PiPe
connEctIons and tERMInatIon
IMpoRtant:
To prevent damage to the gas burner
and ensure proper operation of the unit, installer
must clean and remove all shavings from the inte-
rior of all PVC pipe used on the air intake.
For boilers connected to gas vents or chimneys, vent
installations shall be in accordance with part 7, Vent-
ing of Equipment, of the National Fuel Gas Code, ANSI
Z223.1-latest revision, CSA-B149.1 and B149.2, and
applicable provisions of the local building codes.
Provisions for combustion and ventilation air must be
in accordance with section 5.3, Air For Combustion
and Ventilation, of the National Fuel Gas Code, ANSI
Z223.1-latest revision, CSA-B149.1 and B149.2, or
applicable provisions of the local building code.
These boilers require a dedicated direct vent system.
All air for combustion is taken directly from outdoors
through the combustion air intake pipe. All flue prod
-
ucts are discharged to the outdoors through the vent
pipe.
1. See
Figures #1 – #2
in Section V,
“Combustion Air
and Vent Pipe Requirements,”
for standard two-pipe
roof and sidewall terminations and
Figures #3 – #5
(same section) for concentric vent terminations (roof
termination is preferred). Combustion air and vent
pipes must terminate together in same atmospher-
ic pressure zone as shown. Construction through
which vent and air intake pipes may be installed is a
minimum ¼” and maximum 24” thickness.
2. Combustion air and vent pipe fittings must conform
to one of the following American National Standards
Institute (ANSI) and American Society for Testing and
Materials (ASTM) standards:
• D1784 (schedule-40 CPVC)
• D1785 (schedule-40 PVC)
• D2665 (PVC-DWV)
• D2241 (SDR-21 and SDR-26 PVC)
• D2661 (ABS-DWV)
• F628 (schedule-40 ABS).
Pipe cement and primer must conform to ASTM stan-
dards D2564 (PVC) or D2235 (ABS).
In Canada construct all combustion air and vent pipes
for this unit of CSA or ULC certified schedule-40
CPVC, schedule-40 PVC, PVC-DWV or ABS-DWV
pipe and pipe cement. SDR pipe is NOT approved in
Canada.
For Canadian installations all plastic venting material
must be listed to ULC S636.
3. Combustion air and vent piping connections on
boiler are 2”, but must increase to 3”. Due to po-
tential for flue gas temperatures over 155°F, the
first 5 feet of vent pipe must be CPVC (furnished),
the remaining vent pipe can be PVC. If any el-
bows are employed within the first 2 ½’ of vent,
they must be CPVC. Two 30” pieces of 2” CPVC
pipe and one 2” CPVC coupling are furnished with
the boiler.
(
Figure #11
)
Figure #11
combustion air & Vent piping
3 in. Pipe
Minimum Venting
3 in. Pipe
Maximum Venting
6 ft. in length plus four (4)
90° elbows
60 ft. in length and up to
four (4) 90° elbows
notE:
The exhaust transition from 2” pipe to 3”
pipe must be made in a vertical run. (Transition
pieces not included.)
The length of pipe is counted from the boiler jacket
(air intake pipe) or from vent tee (vent pipe). The first
five feet of “Total Equivalent Length” of vent pipe must
be CPVC.
Reduce the maximum vent length 5 feet per each ad-
ditional elbow.
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