Curious Water Heater Vent & Terminal

[Marc Morin]

I've not seen this gas appliance vent terminal before. The manufacture's web site offers little info. The Cat 1 water heater in the garage uses a 2-foot or so single wall vent connector that transitions to a vertical B-vent run which enters the exposed wood framing flooring overhead where the pipe transitions back to single wall and disappears. The vent pipe is thn routed up a 2nd level chimney chase where it exits the wall as pictured. This seems to be have a single wall collar, no thimble, likely single wall pipe in the wall...anyone seen this before? Of course, all in all--it looks completely wrong.

Thanks

[Rick Cantrell]

As you know, single wall should not pass through walls, floors, attics, or roofs.

[Lon Henderson]

As you know, single wall should not pass through walls, floors, attics, or roofs.
And you can't neck down from a larger flue to a smaller.

[Bob Harper]

CAT I appliances must terminate vertically unless power vented by sidewall.

This appears to be Al29-4C stainless steel special gas vent for CAT III & IV appliance venting. It is single walled uninsulated and not intended for CAT I venting. There is no approved way to attach it to the Bvent since it is not intended for this application. It is all wrong.

[Marc Morin]

It's crazy wrong...thanks!