chimney materials

[beammeup]

I am building my oven in Thailand and I am back to the materials problem. I can not get double walled insulated pipe or a terra cotta liner for my chimney. I could weld my own pipe but would like a simpler solution. Can I just use firebrick without a liner? I do need to go through a outdoor porch roof. There are no codes in Thailand. Can I use single walled pipe incased in firebrick?
Thanks in advance.

[beammeup]

Any ideas would be appreciated. I will probably end up welding my own pipe, maybe stainless, If I feel very adventureus I may try to weld an inner and outer pipe and fill it with vermiculite.

[dmun]

Refractory flue tile IS firebrick - made out of the same hard fired material. If you built your flue out of firebrick, and kept the two inch clearance to combustibles, you should be fine, if you surrounded the firebrick inner flue with a masonry outer liner, spaced by a half inch air gap, you would be better than code. Sometimes you have to improvise, but once you go inside the house, you have to keep fire safety first in mind.

[beammeup]

Originally Posted by dmun

Refractory flue tile IS firebrick - made out of the same hard fired material. If you built your flue out of firebrick, and kept the two inch clearance to combustibles, you should be fine, if you surrounded the firebrick inner flue with a masonry outer liner, spaced by a half inch air gap, you would be better than code. Sometimes you have to improvise, but once you go inside the house, you have to keep fire safety first in mind.

Thanks Dmun, perhaps firebrick halves as the liner and Insulation brick as the outer to save weight?

[dmun]

Insulation brick will absorb water, and crack when freezing - Oops, you're in Thailand. It's still not the best for exterior use. Two layers of splits (half thickness firebricks) with an air space between would be ideal: much more water resistant, and stronger, as well as light.

[beammeup]

Originally Posted by dmun

Insulation brick will absorb water, and crack when freezing - Oops, you're in Thailand. It's still not the best for exterior use. Two layers of splits (half thickness firebricks) with an air space between would be ideal: much more water resistant, and stronger, as well as light.

Great information thanks!

[james]

Hey Beam,

As you can you find single-wall steel chimney pipe, one option would be to connect your brick oven vent directly to the single wall pipe, then insulate that pipe according to best practices, up through your house. You could construct a chamber using firebrick, around the single-wall pipe, leaving space for insulation. The insulation would have to be high heat resistant, and thick enough, relative to it relative eficiency. That is the basic principle behind modern double-wall pipe; they just use high tech insulation.

As a side note, you buy single wall steel pipe for your pizza oven in Italy; and the insualation is up to you. This, in the land of stone buildings.

David, what do you think?
James

[dmun]

The only problem I can envision is that wood smoke by-products are corrosive, and can rust out steel at high temperatures. That's why the old sheet metal barrel stoves you see are a lacework of rust. If you could get stainless single wall pipe, or thicker pipe from a metal suppler (tubing comes in a huge variety of thicknesses and materials) then I'd be more comfortable with this approach.

Again, it's in the house. In a freestanding masonry garden structure, then anything goes.

[beammeup]

My oven is outside but under a patio roof 1 meter from the edge so I will either go through the roof or if I use pipe I will use 2 45 deg sections and go outside the roof but attach to the edge for support (not sure how that would affect the draft). As you can imagine it gets quite warm here so I want to reduce the heat from the pipe so I might put a layor of bricks up to the first 45 around the pipe and pour vermiculite between the pipe and brick or just have an air gap. I may also use fire brick inside then brick outside as discussed earlier.

[Alan]

When I filled my oven surround, I ended up filling the body of the chimney about halfway up. I have a plain terra cotta flue pipe and about 3 or 4 inch space between the pipe and walls. With the oven fired, the outside is completely cool up to the level of the vermiculite. Above the vermiculite, the outside definitely gets warm. So your plan to pour vermiculite into the space is probably a good one.