Combustion Air And Vent Pipe - Dunkirk Q90-125 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.
1. Figures 8 and 9 "Combustion Air and Vent Pipe
Requirements, for standard two-pipe roof and sidewall
terminations and Figures 10, 11, and 12 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.
2. Combustion air and vent pipe fi ttings must conform
to one of the following American National Standards
Institute (ANSI) and American Society for Testing and
Materials (ASTM) standards:
Table 3 - Combustion air and vent pipe fi ttings
must conform with the following:
Item Material
PVC schedule 40
PVC - DWV
CPVC schedule 40
Vent Pipe
SDR-21 & SDR-26 PVC
and Fittings
ABS-DWV
Schedule 40
PVC
Pipe
Cement/ CPVC
Primer
Schedule 40 ABS
• IPEX is approved vent manufacturer in Canada listed
to ULC-S636.
• IPEX System 636 Cements and Primers are approved
in Canada listed to ULC-S636.
Use of cellular core PVC (ASTM F891), cellular core CPVC, or Radel
(Polyphenolsulfone) in venting systems shall be prohibited.
WARNING
!
Use of cellular core PVC for venting fl ue gas could result
in death, serious injury.

6 - COMBUSTION AIR AND VENT PIPE

Standards
ANSI/ASTM D1785
ANSI/ASTM D2665
ANSI/ASTM D1784/
F441
ANSI/ASTM D2241
ANSI/ASTM D2661
ANSI/ASTM F628
ANSI/ASTM D2564
ANSI/ASTM F493
ANSI/ASTM D2235
®
13
3. Combustion air and vent piping connections on boiler
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. See Figure 13.
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.
4. Combustion air and vent piping to be pitched back to
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 13 - Combustion Air & Vent Piping
Combustion Air and Vent Pipe Equivalent Length
3 in. Pipe
Minimum Venting
6 ft. (1.8 m) in length
1 - 90° elbow = 5 ft (1.6 m)
1 - 45° elbow = 3.5 ft (1.1 m)
1- 2" x 3" adapter = 0 ft (0 m)
3 in. Pipe
Maximum Venting
60 ft. (18.3 m) in length and
up to four (4) 90° elbows