Tempcast Leaking?

[shoeless]

Hello!

We have a Tempcast masonry stove that was completed about 18 months ago. It is covered with "cobb," a mixture of clay and sand on all sides except for the top. On top the concrete stove top is exposed. The galvanized double stovepipe goes straight up through a 24' ceiling and the stove draws and burns extremely well.

We initially seasoned the stove according to the manufacturer booklet. As we used it during winter 2006 obviously there was some steam leakage which I attributed to further curing of the stove, and also there was substantial cracking of the cobb covering. This last summer we had a layer of colored American Clay applied with all the cracks filled.

This winter we started it up and have had about 15 nice burns, usually in the morning and at night.

Yesterday we did a burn in the morning and in the early afternoon. At about 6, I loaded the fireplace for either a late-night burn or to be ready for the early morning. However there must have still been coals in the bottom of the stove as the fireplace started itself up.

The fire was a particularly hot one. About 45 minutes into the burn, we noticed a smoke smell. Then we noticed smoke coming from the top of the stove that kept increasing. As smoke started to build up in the house we went through and opened all the windows and pointed a fan out one upstairs to try to blow the smoke out.

The smoke kept increasing and before long there was a good deal of smoke pouring from the seams on top (the seams between the cobb and the fireplace itself. I ended up having to douse the fire by repeatedly throwing buckets of water in it, the house was filled with smoke and breathing had become problematic. The smoke coming from the top of the stove was white, and stopping the fire did not stop the smoke.

My question is, is it possible for a tempcast stove to develop a leak? Did our installer make a mistake by not finishing the top of the stove with cobb (I suspect that should not be a factor since there will always be little cracks where smoke could escape)?

And lastly, there's something in the back of my mind that recalls that the installation instructions called for pieces of cardboard to be between the stove and the cobb overlay, and that the cardboard eventually burns away - is it possible that 18 months into using our stove we only now got it hot enough to burn the cardboard and that this was what took place?

Any thoughts would be much appreciated. Obviously we are very upset because if the stove is actually leaking we have to tear massive amounts of cobb off the fireplace in order to patch any leaks and then pay to refinish. It almost makes me want to tear the whole thing out and put in a conventional freestanding soapstone stove!

Thank you thank you thank you in advance.

 

[d.hebert]

I have a Temp-Cast also and love it. I think the problem may be the exposed concrete top. There needs to be at least 2 inches of concrete poured on top of the two slabs of refractory cement that form the top of the heater core. If you did not do this I'm sure this is the problem. The concrete also must not touch the cob facing and must be separated by the ceramic batting provided in the kit. Hope this helps.

 

[boblee]

I bought a Tempcast corner unit with the bake oven a several years ago 1999 or 2000

I assembled the core about 90% and was almost finnished when I hurt myself .
I couldn't finnish the core at that time so it sat unfinnished for a few years .
During that time the core pieces started to shrink and the joints started coming apart then some of the pieces actually started to crumble and fall apart .

I emailed John Lagamba with photos of the crumbling core and he very graiciously replaced the complete unit with a new one.
All I had to do was pay for the freight I was very happy.

I'm now kind of glad that I wasn't able to finnish the fireplace in the first place as I wouldn't have known that there was anything wrong until after I had finnished the veneer . That would have rotted .

I asked John when I sent the photos what he thought was wrong.

He said that a short while after I had bought my core that he discovered that his refractory cement supplier was putting some kind of ingredient in the mix that didn't belong there and he either changed suppliers or had him change the mix , this might be the same problem your having now
You might want to take a closer look to see if you can spot an deteriation in the core

As costly as these units are they shouldn't fall apart and I'm sure John would probably replace your unit too he didn't hesitate with mine .

I do remember the instructions saying that the top of the core had to have a cap that might be all that's wrong with yours .

Bob

 

[Burn-1]

Shoeless most cob recipes have chopped straw in them. Does yours have any in it? If so then it may be that material pryolyzing which would obviously not be good.

 

[shoeless]

We did not add straw as we did not think havnig a combustible material would be appropriate.

Thanks for the replies, we ended up calling Tempcast and as per their instruction we burned the stove again the next day and ever since with no problem. I suspect that my initial suspicion was correct, that the cardboard between the stove and the cob covering had charred and thus created the smoke.

-Joe

 

[begreen]

Welcome shoeless & boblee. Can we talk you into posting some pictures of your installation? It would be great to see how they turned out.

 

[boblee]

I haven't started my second build yet but it will be this winter I hope.
I'm working on finding a more reliable cement and making some mods to the damper . Tempcast uses a chimney top damper I've decided to use one at the base of the unit that I can close after the fire goes out to hold more of the heat in the core instead of letting it go up the chimney to the chimney top damper which isn't much of a heat trap and I don't think it's very effective.

Bob

 

[Martin Strand III]

I have a TempCast 2000 (https://www.hearth.com/gallery/pics/fireplaces/source/tilestove.html) and am burning it for the 4th winter. I have never experienced leakage or smoke inside the room except when pulling an occasional overdone pizza out of the bakeoven. Id like to think the lack of leakage was from paying scrupulous attention to details of both core and facade construction: especially expansion joints, obliteration of air spaces in the brick and tile facade and the use of materials with all the same basic composition (all clay, where possible) to help keep everything expanding and contracting the same (to minimize cracks from thermal cycling).

I have a manual damper located at the base of the chimney at floor level which has worked well despite some "expert" recommendations that it be located high where it penetrates the ceiling.

Also, drying 3" - 4" thick pieces of split hardwood next to the unit (see photo ref. above) allows me to start a full stacked firebox with a match and just a little crumpled paper. The wood storage area, in burning season, stays 85* - 95* F as measured with my handy dandy little Maverick Infrared Laser BBQ Surface Thermometer (<$20).

Aye,
Marty