Installation Manual

Demand Duo™ H-Series Installation and Operation Manual 19
Three types of venting options are available:
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
Exhaust
Combustion
air
Combustion
air
Combustion
air
Combustion
air
Exhaust
Direct Vent
Non-Direct (Room Air) Vent
Multiple water heaters sharing a combustion air
header and a separate exhaust header that vents
directly through separate penetrations to
Combustion Air
Exhaust
Exhaust
Room Air
For Combustion
Twin Pipe
Combustion air and exhaust vent directly
through separate penetrations.
Room air is used for combustion while exhaust vents to the outside.
Multiple water heaters using room air for
combustion while sharing an exhaust
header that vents directly to the outside.
Direct Vent (Concentric Pipe and Twin Pipe)
1
Non-Direct Vent (Room Air)
2
Common Vent (Indoor Units Only. Direct Vent and Non-Direct/Room Air Vent)
3
Figure 8
Figure 9
Figure 10
Figure 11 Figure 12