Navien NHB-055 Installation & Operation Manual page 47

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.
* 12" (300mm) above the highest anticipated snow level, or as
required by local codes, whichever is greater.
Concentric Sidewall Venting
Combustion Air
Vent
Combustion Air
Vent
Maintain 12"
(300 mm)
1" (25 mm) min.
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" (900 mm) min.
Intake Air
Concentric Roof Venting
Vent
Combustion Air
Combustion Air
Vent
Exhaust Gas
12" (300 mm) min
From any
obstruction
(above, below,
left, or right)
Maintain 12" (300 mm) min
(18" (450 mm) min for Canada)
Clearance above highest
anticipated snow level. Maximum
of 24" (600 mm) above roof
Venting the Boiler 47