Ever have a terra cotta flue liner crack?

[Fio]

I did.

Last weekend, My brother heard a loud "Pop" while the fire was burning. The next day, there was a vertical crack on the flue liner, all the way from the bottom to the top. Luckily, it is located in the back of the oven, so it can't be seen.

I attribute it to the fact that the very HOT fire we were burning was burning soot, and perhaps the soot in the chimney caught fire.

At any rate, I patched it with furnace cement, and it's perfectly OK. I've fired the oven twice since then.

[dmun]

The flue tiles are refractory material, just like firebricks. They are not supposed to crack, and when they do, it's because they are cemented to common masonry that expands at a different rate.

Chimney cleaners talk about cracked liners, so I guess it must happen.

[james]

Fio,

Are you planningon enclosing your flue liner with any insulation and/or decorative housing? You could seal your crack with your handing fireplace caulk, then wrap/hide the liner.

James

[Chris]

The upper section of my two-section flue liner cracked yesterday just before my second pizza party. I had a roaring fire inside that began shooting flames up into the flue.

It was a thin crack, running from top to bottom. The upper liner is bonded to the liner below with refractory mortar, and it not attached to anything else. As far as I can tell, the lower liner is intact.

I have metal studs surrounding the flue, waiting for hardibacker and stucco. Should I replace the inexpensive liner section? I could cut it out with a diamond saw and put a new one on. I'm slightly worried that I'll either crack the lower liner, or break the mortar bond of the lower liner to the vent arch.

I could also go get some furnace caulk, if I knew where to find it. I bet the caulk is more expensive than the liner!

Would refractory mortar work if I mixed it nice and thin?

Should I just fill the chimney enclosure with perlite and forget about it?

[Xabia Jim]

What is a flue liner for....?

It prevents noxious gases from escaping to indoor areass and prevents fires from starting in nearby materials (like wood stud walls). I would guess that in many outdoor wood fired ovens there is little chance of either of these issues being a problem.

If it's part of an occupied structure, I'd evaluate it a little more....but a crack is not a big problem with a masonry oven....you will probably have them!

Forget it, or patch it and be happy!

my 2 cents
Jim