space between drop flues and arch brick?

[owarzecha]

So I am wondering what is the ideal space between the drop flues and the Arch brick. also should the arch be sloped or should that space be constant along the entire length of pan? see attached for diagram of the build.

[whalems]

I have been told 1/2". That is what I went with. Also in your desing I see that your stack comes out the back. Most commercial made rigs extend there arch a little longer and come straight up out of the top. I could think that would keep the heat up on your pans better. I am no expert just thinking out loud :) Hope that helps, Mike

[Paperman]

If the flue areas math works right I would try and get them as close to the bottom as possible. Logic would reason that any gas that skims along the bottom is not giving up its heat to the pan.

[xulgiy]

I ran my homemade rig (2x5) with a square back wall that came right up to the flues for two years. Trying to get better efficiency, I sloped it last year and now have about a 12 inch drop from back to front. I'm not sure why, but the efficiency went way up. So...yes, I'd slope it.