Chimney thimble connection

[tabner]

I'm getting pretty fed up with installers who don't know anything about the new EPA stoves, take 3 weeks and 2 follow ups from me to send a quote, refuse to install dampers, etc. I'm leaning toward installing myself. Only connection I'm not sure about is this chimney thimble. These photos are of my oil boiler exhaust currently connected. Oil will be removed, chimney cleaned, and I will need to connect my double wall stove pipe here. This appears to be an 8" tile thimble? It seems about a 7.5" ID. That oil boiler pipe is 6" single wall. It appears my oil company has simply jammed rockwool to fill the gap and then hit it with some cement. Is this the correct way to attach my double wall when I install the stove? Or is there some type of adaptor needed?

 

[DAKSY]

See page 5

https://icc-rsf.com/wp-content/uploads/2020/07/ULTRABlack_CAT_SECTION_2020_EN.pdf

 

[tabner]

See page 5

https://icc-rsf.com/wp-content/uploads/2020/07/ULTRABlack_CAT_SECTION_2020_EN.pdf

Awesome! Thank you!

 

[bholler]

I'm getting pretty fed up with installers who don't know anything about the new EPA stoves, take 3 weeks and 2 follow ups from me to send a quote, refuse to install dampers, etc. I'm leaning toward installing myself. Only connection I'm not sure about is this chimney thimble. These photos are of my oil boiler exhaust currently connected. Oil will be removed, chimney cleaned, and I will need to connect my double wall stove pipe here. This appears to be an 8" tile thimble? It seems about a 7.5" ID. That oil boiler pipe is 6" single wall. It appears my oil company has simply jammed rockwool to fill the gap and then hit it with some cement. Is this the correct way to attach my double wall when I install the stove? Or is there some type of adaptor needed?

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Are you installing into an uninsulated clay lined chimney?

 

[tabner]

Are you installing into an uninsulated clay lined chimney?

Yes, right now that's the plan. It's an 8" square tile lined masonry chimney. it goes up through the center of the house through two floors and the attic.

 

[tabner]

It's kind of unusual because I have to go through a combustible wall and then there's about 10" gap and then you hit the masonry thimble in this picture. So I'm thinking insulated wall thimble, but then I also need the masonry adaptor, so im just not sure

 

[bholler]

Yes, right now that's the plan. It's an 8" square tile lined masonry chimney. it goes up through the center of the house through two floors and the attic.

I really don't see the point in double wall in that case. Once you hit the chimney you will be loosing heat really quickly.

Does the outside of the chimney have the required 2" clearance to combustibles?

 

[bholler]

It's kind of unusual because I have to go through a combustible wall and then there's about 10" gap and then you hit the masonry thimble in this picture. So I'm thinking insulated wall thimble, but then I also need the masonry adaptor, so im just not sure

Yes you need an insulated thimble no masonry adapter needed

 

[tabner]

I really don't see the point in double wall in that case. Once you hit the chimney you will be loosing heat really quickly.

Does the outside of the chimney have the required 2" clearance to combustibles?

The double wall is because it's sort of installed in a corner and I want to have the 6" wall clearance off the back of the stove. Hard to explain without a picture.

As far as 2" clearance. Interestingly neither of the installers that have looked at it have commented on that issue - yet again, I have little faith in them. I just checked it out with a flashlight and it's hard to tell, because you can only see up about three feet, which is where the first floor starts, and it looks like some metal flashing all around the chimney. But it looks like all joists and subfloor have been installed 3" plus away from the chimney, and they just used aluminum flashing to butt up against the cement, probably to stop drafts between floors. I bent back a piece of flashing and can just peek up there with a flashlight, can't see any lumber, just several feet of cement with several inches around it. House was built in 1987, and the original owner did use the chimney for a basement woodstove, likely they had the 2" clearance rule then?

Yes you need an insulated thimble no masonry adapter needed

The problem I'm having is 4" through the wall and then 10" gap between the wall and the chimney. None of the insulated thimbles I've seen extend that far.

 

[bholler]

The double wall is because it's sort of installed in a corner and I want to have the 6" wall clearance off the back of the stove. Hard to explain without a picture.

As far as 2" clearance. Interestingly neither of the installers that have looked at it have commented on that issue - yet again, I have little faith in them. I just checked it out with a flashlight and it's hard to tell, because you can only see up about three feet, which is where the first floor starts, and it looks like some metal flashing all around the chimney. But it looks like all joists and subfloor have been installed 3" plus away from the chimney, and they just used aluminum flashing to butt up against the cement, probably to stop drafts between floors. I bent back a piece of flashing and can just peek up there with a flashlight, can't see any lumber, just several feet of cement with several inches around it. House was built in 1987, and the original owner did use the chimney for a basement woodstove, likely they had the 2" clearance rule then?


The problem I'm having is 4" through the wall and then 10" gap between the wall and the chimney. None of the insulated thimbles I've seen extend that far.

You may need a custom extended thimble. If you actually have the required clearance that is great very few do even with new construction