Gas Fireplace Flue Type?

Gas fireplace flue question. There was no label on the flue pipe that I could see. I’m not sure if it’s a “type B” flue. I could not find any similar pictures of this type of flue to help identify. Pictures are from the attic. It’s 1" from combustable material. Any insight would be appreciated!


looks like b from here
i never second guess unlabeled vents
consult a competent plumber or hvac tech to conclusively verify
from your posts finding 1 maybe difficult

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I agree with Bear. Did you get a picture of the top? That may help.

the cap may b
the flue pipe is what is in question & i wouldn’t ever rely on a cap or other component for flue id
just how i roll & no offense meant

Often the cap comes right off with a slight twist and the view gets better…no offense taken…thanks.

That spiral duct would have me calling that out in a heart beat. I don’t believe fireplace flues are spiral.

We had some back in the 80’s (and maybe early 90’s) that were triple-wall where the out side pipe was spiral.

Well, I never did here in Northern Maine where 75% use wood, gas, and pellets.
But I have seen plenty of spiral ducts used on commercial buildings just like it.

This is the best photo I have of the cap. Flew my drone to get the roof.

I literally cannot find anywhere any information about this type of flue. I’ll just recommend a chimney sweep identify it.

Edit: I found it. It’s single wall galvanized spiral ducting. Writing it up.

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Excellent, Jacob!

Where did you find it?

What was the diameter of the exterior of the pipe?

I actually just googled the type of pipe you said was common in your area and compared a ton of “spiral stove pipes” to the one I have pictures of. Did a process of elimination; double and triple wall stove pipes are stainless and single wall is galvanized. The pictures of the galvanized pictures looked exactly like what is in this house.
The size of the stove pipe is 8".

This is what I was having a issue with.

That tells the story fairly well. The triple wall diameter was 12"…as I recall.

P.S. you may want to report that it appears to be single wall…

Ooooo yes, good point. Thanks! You’re the man as always.

Another picture farther away.

Outer dimension is 4" larger then inside diameter of chimney (8inch chimney is 12" on outside).


Still 2" to combustibles haha. I couldn’t imagine someone put in a single wall like this.

Ya, triple wall needs 2" clearance…

If this is triple wall. Could be double? Double would need 6" then…