Question about bricks for vent

[Frances]

This may be a really dumb question, but why can you use regular bricks for the walls of the vent? Won't they get too hot touching the sides of the dome?

If you cast a vent out of concrete, would this be regular concrete or the heat resistant kind? (And if not why not?)

I can't find any double (or tripple) walled chimneys around here, so would it work with a single walled metal one? I thought I'd wrap it in insulation and cover it with chicken wire and mortar like the oven afterwards.

And while I'm asking questions (just thinking ahead a bit here) what does a clay flue liner look like? What does it do?

Building the dome I can visualise, but the chimney/vent bit is still a bit of a blank

Frances

[dmun]

This is what a refractory flue tile looks like:



They are square (or rectangular) in the US, they are round like drain tile (but made of refractory material) in Europe. They should be available anywhere that sells firebrick, for masons building fireplaces. The flue tile is supported by the entry of your oven, and has freestanding brick (or other masonry material) built around it. The advantage to using flue tiles is that they will last a lifetime, where metal stove pipe will corrode with the hot, acidic environment that flues produce.

If your oven is outside, and freestanding, a metal flue may do fine, particularly if you arrange it so it can be pulled out and replaced when it rusts out. If it's inside, you have to adhere to building code, meaning engineered flue systems, or proper lined masonry chimneys.

As for the transition from entry arch to flue, I built mine out of firebrick, and I recommend this. Fire brick isn't that much more expensive than red common brick, and it's easier to cut into the strange shape that a funnel requires.