Navien NCB-180 Installation & Operation Manual page 43

Non-concentric Sidewall Venting – Air is drawn from a different
●
location that is at least 12 in (300 mm) away from the exhaust
termination. Try to minimize the length of the intake air pipe
with this venting.
Concentric Sidewall Venting
●
Combustion Air
Vent
42 Venting the Boiler
Combustion Air
Vent
Maintain 12"
1" (25mm) min.
(300mm) min*
* Clearance above
highest anticipated
snow level or grade.
2 in or 3 in Two-pipe Vertical Venting – Intake and exhaust pipes
●
do not have to terminate in the same area.
36" (900mm) min.
Intake Air
Concentric Roof Venting
●
Vent
Combustion Air
Combustion Air
Vent
Exhaust Gas
12" (300mm) min
From any
obstruction
(above, below,
left, or right)
Maintain 12" (300mm) min
(18" (450mm) min for Canada)
Clearance above highest
anticipated snow level. Maximum
of 24" (600mm) above roof