Dunkirk DCC-150 - Twin Pipe Systems

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6 - COMBUSTION AIR AND VENT PIPING
Twin Pipe Maximum Vent Lengths
125/150 165/205
3" [80 mm] 3" [80 mm] 2" [ 50 mm]
Intake Vent L1 49 ft 100 ft 85 ft
Exhaust Vent L2 51 ft 100 ft 85 ft
Combined Vent L1+L2 100 ft 200 ft 170 ft
Single Wall Elbows - Equivalent Length

3" 2"
45° bend 0.82 ft [0.25 m] 3 ft [0.91m]
90° bend 1.64 ft [0.50 m] 5 ft [1.5 m]
NOTE: Two pipe separated ue can run horizontal or vertical.
FIGURE 6-7 - Twin Pipe Separated Horizontal Flue
Termination
6.8 Twin Pipe Systems
Twin pipe venting allows exhaust ue and intake ue to be
separated from each other. Fresh air is drawn in at a different
area from the ue terminal location.
A. Twin Pipe CPVC System
CPVC is approved for boiler exhaust. CPVC or PVC are both
approved for air intake.
To transition from Coaxial at the top of the boiler to Twin Pipe
CPVC/PVC a kit is available.
B. Twin Pipe Polypropylene System
Single wall polypropylene is used for both exhaust and air
intake piping.
To transition from Coaxial at the top of the boiler to Twin Pipe
polypropylene venting an adapter kit is available.
C. Twin Pipe Separated Flue
Exhaust and combustion air intake are not located in same
general location.
D. Twin Pipe - Common Atmospheric Zone
Termination
FIGURE 6-8 - Twin Pipe on Roof Combustion Air On
Sidewall
Vent Terminal
Combustion Air
Ground
Level
Combustion Air
FIGURE 6-9 - Twin Pipe Flue On Sidewall, Combustion
Air On Roof
240011947 REV B, [03/31/2018]
12" (305mm)
Anticipated Snow Line
Vent - T Terminal