I ran across this on an inspection the other day. I called the installer of this unit and he told me this was correct. You can see by the picture that the secondary air vent pipe and the furnace gas exhaust pipe have been joined before they exit the exterior wall of the home. The lower pipe is the air vent pipe and the upper is the exhaust pipe. It seems to me that this is not okay. Comments?
Yep, Mike’s got it.
A concentric vent kit: