Combustion Air And Vent Pipe - UTICA BOILERS UB90-200 Installation, Operation & Maintenance Manual

Connections And Termination
To prevent damage to gas burner and ensure
proper operation of unit, installer must clean
and remove all shavings from interior of all
PVC pipe used on air intake.
Boilers require dedicated direct vent system. All air for
combustion is taken directly from outdoors through
combustion air intake pipe. All fl ue products are discharged
to outdoors through vent pipe. Install vent system in
accordance with these instructions.
See Figures 1 – 2
1.
Requirements, for standard two-pipe roof and sidewall
terminations and Figures 3 – 5 for concentric
vent terminations (roof termination is preferred).
Combustion air and vent pipes must terminate
together in same atmospheric pressure zone as shown.
Construction through which vent and air intake pipes
may be installed is minimum ¼" and maximum 24"
thickness.
Combustion air and vent pipe fi ttings must conform
2.
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 standards
D2564 (PVC) or D2235 (ABS).
In Canada construct all combustion air and vent pipes
for this unit of CSA or ULC certifi ed 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.
Combustion air and vent piping connections on boiler
3.
are 2", but must increase to 3". Due to potential for
fl ue gas temperatures over 155°F, fi rst 5 feet of vent
pipe must be CPVC (furnished), remaining vent pipe
can be PVC. If any elbows are employed within fi rst
2 ½' of vent, they must be CPVC. Two 30" pieces of 2"
CPVC pipe and one 2" CPVC coupling are furnished with
boiler. (Figure #11)

COMBUSTION AIR AND VENT PIPE

NOTICE
"Combustion Air and Vent Pipe
Length of pipe is counted from boiler jacket (air intake
pipe) or from vent tee (vent pipe). First fi ve feet of "Total
Equivalent Length" of vent pipe must be CPVC.
Reduce maximum vent length 5 feet per each additional
elbow.
Combustion air and vent piping to be pitched back to
4.
boiler at minimum ¼" per foot (21mm/m) from intake
and vent terminals so that all moisture in combustion
air and vent piping drains to boiler. Pipes must be
pitched continuously with no sags or low spots where
moisture can accumulate and block the fl ow of air
or fl ue gas. Combustion air and vent pipes must be
airtight and watertight.
Figure 11 - Combustion Air & Vent Piping
Exhaust transition from 2" pipe to 3" pipe
must be made in vertical run. (Transition
pieces not included.)
3 in. Pipe
Minimum Venting
6 ft. (1.8 m) in length
13
NOTICE
3 in. Pipe
Maximum Venting
60 ft. (18.3 m) in length and
up to four (4) 90° elbows