Dunkirk DWB Series - Manual (Page 18)

18
WARNING
Vent extending through exterior wall shall not
terminate adjacent to wall or below building
extensions such as eaves, balconies, parapets or
decks. Failure to comply could result in death or
serious injury.
!
Table 3 - Combustion Air and Vent Pipe Fittings
6 - COMBUSTION AIR AND VENT PIPING OF DIRECT VENT AND CATEGORY III
10. If the horizontal vent must go through a crawl space or
other unheated space, the cool temperatures will likely
cause the fl ue gases to continuously condense inside
the vent pipe. Do not insulate the vent pipe. It must be
visible for monthly inspection. Insure that the vent pipe
is properly pitched away from the boiler, with no low
spots, so that condensate in the vent will drain away
from the boiler. An insulated enclosure or chase, with
access for inspection and servicing of the vent, may
be required to prevent freezing of liquid condensate.
Consult the vent pipe manufacturer’s instructions for
specifi c guidelines.
11. At beginning of each heating season and monthly
during the heating season, check all vent pipes and
vent terminal to make sure there are no obstructions.
Periodically clean the screen in the vent terminal.
Equivalent Length of Venting Components:
5 ft. equivalent for a 3” 90° elbow.
2 1/2 ft. equivalent for a 3” 45° elbow.
Type Item Diameter Min Lenght Max Lenght Material Standards
Direct vent
Vent 3” 5 ft 65 ft
AL294C Stainless
Steel, Aluminum
UL1738,
ULC S636
Air intake 3” 5 ft 65 ft
Stainelss Steel,
PVC, CPVC, PP,
Aluminum
ANSI/ASTM
D2564, ANSI/
ASTM F493, UL
1738/ULC636-08
Category III Vent 3” 5 ft 65 ft
AL294C Stainless
Steel, Aluminum
UL1738,
ULC S636