Hearthstone iii Top Stones...Cement?

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Nov 23, 2021
Hi Everyone. I picked up a barely used little Hearthstone iii this year and we have been using it with great success after a thorough cleaning. We recently replaced the door/glass gaskets. After a day of 65+MPH winds and crazy gusting, I got some back-drafts out of the top of the stove that scared the life out of me. We have good draft and venting, that has all been examined. This is the fully manual model from the mid-1980s. Stove was inspected (twice), and this was chalked up to the extreme conditions and to the fact I really can't get this stove over 400/450 degrees because it is so small.

The top three stones have channels by which they connect. I believe they were sealed with cement at one point it time, but after removing them for transport and cleaning they now come apart easily. I feel like I want to cement them back together by placing a small amount of cement in the channels where they insert and connect.

Does any one have any experience with this? Stove guy that was here said to add a gasket around the top casting where the stones lay, so I have done that....I'm thinking that the stones may have even been cemented in there at one point in time.

Thoughts? Suggestions?

Thank you!

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Contact your local Hearthstone dealer. Hearthstone uses its own brand of stove cement & it is available in caulking gun sized tubes. Not cheap, but it works very well. I have re-cemented a half dozen or so Hearthstone stoves using their product. It cleans up with water if you get it before it dries.
Thanks Bob for your reply!

I did read about their special cement that contains fiberglass I believe? What are your thoughts about the gasket under the 3 top stones? Should I just cement them in place in the cast instead? I like the idea of being to at least remove the 3 together for the opportunity for future replacement if needed....but I also want this thing to be TIGHT. Thanks again- Stephanie
Hearthstone cement is sold by Woodmans
Not this stove, but did you see the Kevlar_vw posting on the rebuild of a Hearthstone II?
Soooooo My "local" (2 hours away as I'm in the middle of nowhere, just as I like it), dealer called Hearthstone and they said to lay a thin bead of "any" cement around the top cast edge and lay the stones. They didn't tell them what to relay to me re: BETWEEN the stones. I already laid a gasket...wondering if I should take it out and use cement. They (Hearthstone Factory) said to use Rutland or whatever I want..... FYI I've been burning it for 3 months with nothing there at all...until the 65 MPH winds and backdraft issue which caused me to start investigating further.
Hearthstone cement is sold by Woodmans
Not this stove, but did you see the Kevlar_vw posting on the rebuild of a Hearthstone II?
Thank you for reposting I did read it. I see channels in the stone on that post too on the sides and obviously that is filled with cement. The guy who inspected the stove told me to lay a gasket so I did.... but now I am feeling like I want to rip it our and just cement the **** out if it.....Argh.
Well boys……I’m down the rabbit hole now! Removed the top cast and replaced the top internal gasket at the top of the firebox which was essentially disintegrated…..So feeling good about that. Does anyone know what the whitish compacted material is that the top cast is lined with? I’m headed to the stove shop this week sometime. I see another gasket on the bottom, it also looks crunchy. I love the look of this stove, but I need bigger so when I sell it I want to feel good about it’s condition when I do. Man this is a labor of love…..

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