Hi guys,
I've scratched my head on this image for a good hour. It makes no sense to me.
There zero chance B is the inside diameter and 17" if A is the outside square and is 10-1/8" it's just physically impossible. I don't have my chimney yet but i need to cut the hole for it. So I need to know what size diameter hole i need to fit this thimble in nicely. It's not something I can fix later as I'm having someone with a core drill come and do it. This diagram from Selkirk doesn't make me comfortable. What i know is the inside diameter of chimney is 6" I can't even find the outside diameter info on it but i'm assuming is 2" of insulation and might be 8" so if you add 1/8 for 2 layers of steal and another 2" for air clearance, i could guess that it's the 10-1/8 and maybe they just got the diagram wrong. But like i said. I can't make a mistake on this one so asking for anyone who has already installed one of these, what size hole did you drill?
I've scratched my head on this image for a good hour. It makes no sense to me.
There zero chance B is the inside diameter and 17" if A is the outside square and is 10-1/8" it's just physically impossible. I don't have my chimney yet but i need to cut the hole for it. So I need to know what size diameter hole i need to fit this thimble in nicely. It's not something I can fix later as I'm having someone with a core drill come and do it. This diagram from Selkirk doesn't make me comfortable. What i know is the inside diameter of chimney is 6" I can't even find the outside diameter info on it but i'm assuming is 2" of insulation and might be 8" so if you add 1/8 for 2 layers of steal and another 2" for air clearance, i could guess that it's the 10-1/8 and maybe they just got the diagram wrong. But like i said. I can't make a mistake on this one so asking for anyone who has already installed one of these, what size hole did you drill?
![[Hearth.com] What size hole to drill for 6" chimney? [Hearth.com] What size hole to drill for 6" chimney?](https://www.hearth.com/talk/data/attachments/248/248865-320bf8a0f5fedb95245faaf33f9163a4.jpg?hash=To8BnENK7Z)
![[Hearth.com] What size hole to drill for 6" chimney? [Hearth.com] What size hole to drill for 6" chimney?](https://www.hearth.com/talk/data/attachments/248/248895-99ecad764ef40fd602ae5864703fc071.jpg?hash=d1QD4t-LiX)
![[Hearth.com] What size hole to drill for 6" chimney? [Hearth.com] What size hole to drill for 6" chimney?](https://www.hearth.com/talk/data/attachments/248/248896-d69a12b07373fef465d78f63bfc169c1.jpg?hash=XxuVubxN1t)