Odd sized masonry thimble?

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arngnick

Member
Feb 15, 2013
245
Mansfield, PA
I am struggling with connecting to my thimle. I have a standard 8 inch masonry chimney that is outside. My thimble seems to be an odd size 6.5" inside and slightly larger than 8 on the outside diameter.

Is this an odd size thimble that I should replace with something that would be more accepting? Or is there a good way to adapt to this...(6" is to small 7" is slightly to large and 8" almost fits on the outside of the thimble)
 
Do you know what brand pipe this is? If not, can you post a picture? It might be designed to use an adapter for the connector pipe.
 
I cannot get a picture. I am currently hooked to it using a flashing adapter (my flue temps stay low) It is a clay thimble run through a poured wall. the inside measurement is 6.5" and the outside is slightly more than 8".
 
I cannot get a picture. I am currently hooked to it using a flashing adapter (my flue temps stay low) It is a clay thimble run through a poured wall. the inside measurement is 6.5" and the outside is slightly more than 8".

For clarification: By inside and outside I mean inside diameter and outside diameter.
 
In that case I think I would just pack around the connector pipe with some stove gasket material for a tighter seal.
 
What I have is working, I just want to know the correct way it should be done. I have an 8 inch pipe going almost around it with flashing that bridges the gap. I may just find something that fits and weld a flue box with the proper size pipe that fits inside. Or I could always replace the flue with something that is more standard. Just seems to be odd size no standard size pipe will fit.
 
Hard to say. It doesn't sound like an intended connection. Again, a picture is worth a lot here. There could be issues that are not ok that we are not seeing. Is this single wall pipe? If so how are clearances to combustibles?
 
My flue temps run 400 on the high side. The thimble is clay and I have an 8" single wall pipe goint to it. Combustables are at least 30" away.
 
(broken image removed)\

It is one of these through a poured wall with the measurementslisted above.
 
Did you ever find a solution to this? I have the exact same problem. My only other issue is that the stove has an 8" outlet. When I came into this, the 90deg elbow was just jammed into the thimble and leaky as can be. I have made it a little better by undoing a section of 8" stove pipe and sliding it into the wall. I have an 8" to 6" reducer that pokes into that for a much better seal. I just need something that will work better until we run a new chimney straight out of the roof.
 
I have not...I plan to do some more research and replcae the timble soon. Let me know how you make out.
 
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