Chimney Flue considerations

[spiderrinaldi]

Hello all,

I have another thread going for my Pompeii oven build, but I wanted to post a few questions outside of that thread as it would help others find answers easier.

Questions:
1. Since my oven is going to be enclosed, and weather proof, does it make any sense to buy a Stainless Steel Chimney. There is obviously a big difference in price between an aluminum pipe and SS. Obviously, I figure the rain cap should be SS because that will be exposed to the elements. I just don't see a reason to spend the extra money.

2. Double wall or single wall? Again, a big difference in price. If I understand correctly, the difference between the two is related to insulation of the pipe. I understand double provides insulation, but how important is insulation in the venting system? Is it primarily for clearance purposes, meaning you could have the pipe sit closer to the enclosure walls? Since you would be using a heat tolerant enclosure wall, like a cement board, does this really matter too much? And can you simply angle the pipe away from the walls to solve this problem?

Thanks for all your help.

[Tonyp]

Re: Chimney Flue considerations

Hi Spiderrinaldi,

The insulation helps the flue stay hot throughout it's length so it drafts better and keeps creosote from forming by cooling gases. I suspect that with the short straight runs for most pizza ovens and the pretty hot burn in the oven this is not an issue. The insulation then would be primarily for clearance to combustible material. A single wall needs 18" clearance while a double wall only 6". You could certainly build your enclosure with all your combustible material a safe distance from the pipe and use the steel single wall pipe. Be careful though because cement board that is very close to single wall pipe will get nearly as hot as the pipe.

If you plan to extend the pipe through a roof you will also need to consider the combustible situation there with regard to construction and finishing the roof.

[spiderrinaldi]

Re: Chimney Flue considerations

Thanks Tony. As I think about the SS vs. Alum. question, I realize that part of the pipe will most likely still protrude out of the enclosure, so I would probably want to get stainless steel. I guess, I should have thought of that before I posted.