Navien NPN Installation & Operation Manual page 38

Clearances for sidewall terminations
Multiple-unit, concentric wall terminals: Space each
concentric wall terminal at least 12 in (30 cm) apart,
regardless of the orientation. A concentric wall
terminal must also be at least 12 in (30 cm) away
from the inside corner of a wall. If the adjacent wall
is less than 12 in (30 cm) in length, the minimum
required distance away from the inside corner will
be equal to the length of the adjacent wall.
To inside
corner
12" 12"
Between terminals
at the same level
[NPN-160U/180U/199U]
12" 12"
To To
inside inside
corner corner
[NPN-120E/160E/180E/199E]
12" 12"
Between terminals Between terminals
at the same level at the same level
2" 2" 36"
36"
To To
ventilated or ventilated or
unventilated unventilated
soffit, eve soffit, eve
vent, deck, vent, deck,
or porch or porch
60" 60"
Vertically Vertically
between between
terminals terminals
Clearances for rooftop terminations
The minimum spacing required between multiple
concentric terminals on different levels of a rooftop
is 60 in (150 cm).
60" 60"
60" 60"
[NPN-160U/180U/199U]
Installing the Water Heater 37