Rinnai Tankless Water Heater Installation and Operation Manual
37
1. Direct Vent
(Concentric Pipe)
Concentric Pipe Overview
Combustion air and exhaust vent directly
through a single concentric connection.
Hot exhaust exits through the interior tube,
while combustion air enters through the
outer layer.
Combustion
air
Exhaust
Combustion
air
Concentric Pipe Termination Clearances
Inside
Corner
12 in.
(0.30 m)
12 in.
(0.30 m)
60 in. (1.52 m) ver�cally
between terminals
60 in. (1.52 m)
Note: 24 in. (0.61 m)
to wall or parapet
12 in. (0.30 m)
All terminations (horizontal and/or vertical) must terminate 12 in. (0.30 m) above grade or anticipated
snow level.
Figure 23: Concentric Pipe
Figure 24: Between terminals at
different levels
Figure 25: Between terminals at same
level
Figure 22: Concentric Pipe Termination Clearances
Corner
