Rinnai M060C Installation And Operation Manual page 23

Two venting options are available: Direct Vent and Non-Direct Vent (Room Air).
Direct Vent (Concentric and Twin Pipe)
Option 1
Concentric Pipe
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.
Exhaust
Combustion
air
Option 2 Room Air
Exhaust
Rinnai M-Series Condensing Boiler Combi Manual
Combustion
air
See Room Air section for complete details.
Combustion
air
See Direct Vent section for complete details.
Twin Pipe
Combustion air and exhaust vent directly
through separate penetrations.
Exhaust
Exhaust
Combustion
air
Combustion air
Room air filter
(accessory)
23