There was a floor furnace and there is now a FAU in the attic. The abandoned Transite flue has been used as a chase for CSST and Romex. It's also a path from the crawlspace to the attic. Do you ask them to seal it?

Well I put this in the wrong place. If a meddling moderator happens by, perhaps you can move it to residential.

Well I put this in the wrong place. If a meddling moderator happens by, perhaps you can move it to residential.