Combustion Air/ Vent Requirements - Dunkirk Q90-125 Installation, Operation & Maintenance Manual

Combustion Air/Vent Pipe Requirements
Boiler requires dedicated direct vent system. Direct vent
system, all air for combustion is taken directly from outside
atmosphere, and all fl ue products are discharged to outside
atmosphere.
Combustion air and vent pipe connections must terminate
together in same atmospheric pressure zone, either
through roof or sidewall (roof termination preferred). See
Figures 8 and 9 for required clearances.
Figure 8 - Roof Vent / Intake Terminations
12" (305mm)
Minimum
8" (203mm)
Minimum
Vent
12" (305mm)
Minimum Above
Anticipated Snow Line
Figure 10 - Concentric Vent Terminations
1" (26mm)
Maximum
Combustion Air

5 - COMBUSTION AIR/ VENT REQUIREMENTS

3" (76mm)
Maximum
15" (381mm)
Maximum
Combustion
Air
Vent
Figure 9 - Sidewall Vent/Intake Terminations
12" (305mm)
Minimum From
g
Overhan
See Snow &
Ice Page 23
• Avoid locations where
snow may drift and block
vent and combustion air.
• Ice or snow may cause
boiler to shut down if
vent or combustion air
becomes obstructed.
Combustion Air
If concentric vent termination is being used, refer to
Figure 10 for proper setup.
1" (26mm)
Maximum
* See Note
Below
Combustion Air
*Must be less than 4" or greater than 24" Horizontal distance
between end bells of each air intake to prevent fl ue gas recirculation.
11
3" (76mm)
Minimum
Separation
12" (305mm) Separation
Between Bottom Of
Combustion Air Intake
And Bottom Of Vent
Vent
Combustion Air
12" (305mm)
Minimum
Separation
Vent
Overhang
12" (305mm) Minimum
36"(0.9m) Minimum
Maintain 12"
clearance above
Maintain 12"(305mm)
Vent
highest anticipated
Clearance Above Highest
snow level or grade
Anticipated Snow Level
Or Grade