What do you think?

???

forgot the picture

HPIM3418.JPG 2.jpg

If it’s an unconditioned space (looks like an attic) all flue piping should be type “B” double wall pipe.

This type of flue collector box generally will not meet code, and I agree it must be in double wall be vent in the attic

Okay, I’m going to go out on a limb here, “B” vent is needed at the minimum.:stuck_out_tongue: