Chimney materials

[lwood]

I couldn't find anything on all the different materials used for the chimney. Is it just stainless steel or flue tiles? Or are their other alternatives? Can I use galvanized sheet metal?

[dmun]

Can I use galvanized sheet metal?

Ordinary galvaninized stove pipe will rust out in a season or two. You could have a vent welded up out of heavy gage steel, but remember, it will get really hot on the outside unless it's insulated and enclosed.

[nissanneill]

lwood,
if you check out my chimney, I have used a stainless for the void and because I had some galvanised 8" flue just lying around waiting for a use, I incorporated it into the build. It won't last as long as stainless steel, but I expect 15+ years out of it as i got over 25 years from the same material in my slow combustion heater flue.
Others on the forum get much less time out of galvanised steel, but like many goods, there are different thicknesses and grades available.
Getting a nice 16g 8" flue rolled out of 36 stainless would be my choice but I imagine that it would cost megabucks when compared to what I have used.
People also criticise galv for toxic gas emissions but it is outside the oven and in the outdoors, so if any are produced, they will not be of any consequence
Your location, application, and envirinment will also dictate what you use, but I see the choices as:
• Galvanised steel, • Stainless steel, (grades 304 or 316), • terracotta flue (either, square, rectangular or round, • brick, • stone, or a combination of several.
I personally feel that the round flues draw better as they heat up quicker and have less drag coefficient than brick, stone or even terracotta (which would be my second choice if I could find the suitable size and shape required).
Another choice would be a plastic liner (thinner the better) and wrapped in chicken wire and then plastered with refractory material. I would vibrate the inside of the flue to ensure a nice clean smooth inner surface and then remove the plastic once dry. This way you can make your own size, shape and style flue/chimney. Other options would be to use a plastic sheet wrapped around a metal flue which would make the stripping out of the pattern (metal flue) easier and then pull out the plastic to expose your chimney.
Anything is possible, all you need is an idea and then to just go for it.

Neill

[lwood]

Just checking, stainless steel and insulating perlcrete is the way I think I'll go. Lighter weight, long lasting, easier to install, and want to finish it all the way to the ceiling with a broken tile design.. Thanks for the input

[ThisOldGarageNJ]

lwood,

Just make sure the pericrete will have enough structural support, you may want to give it a final render of stucco for stability as pericrete is only strong in compression...

Cheers
Mark

[lwood]

Hi Mark,
The chimney will be supported, from lateral movement, by a poured concrete roof 5 feet above the oven. My main concern is weight. Will the weight of the pericrete be too much for the archway? Thanks John

[ThisOldGarageNJ]

lwood,
I built my chimney out of fire brick and i havent had any problems.. It shoud easily take that weight,, here is a pic before i was finished, I added one more course after that, so at 9 lbs a brick x 20 =180 lbs... As long as your arch is cured and solid you should be golden,,

Cheers
Mark