Concentric Vent
Concentric venting describes any coaxial "pipe in pipe" venting design where the intake air and exhaust gas both vent through a shared assembly.
It can provide an aesthetic installation with a single wall or roof penetration.
Concentric venting may be used with several types of water heaters, including direct vent, power direct vent, and tankless water heaters.
However, the material of the concentric venting may be different depending on the water heater.
Concentric venting may be used for the full vent run (from water heater to outside of the home) for certain models that are exclusively designed for concentric venting,
such as a direct vent water heater or concentric vent tankless model.
A concentric vent termination may be used on a power direct vent tank or tankless water heater to get the same benefit of a single wall or roof penetration with an aesthetic vent termination.
In that installation separate intake and exhaust vent pipes are run between the water heater and interior wall, and only the wall penetration and termination are concentric piping.
We recommend that you consult a professional plumbing contractor for installation.