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View Full Version : How do I size my smoker exhaust?


S-L-A-C-K-E-R
09-20-2010, 09:15 AM
So, here's my big thread on my brick bbq pit that I'm trying to modify for smoking...

http://www.bbq-brethren.com/forum/showthread.php?t=88895

Here's my question.

I think I have determined (with the help of all of you on the board) that the chimney is way too big for what I'm trying to do. Plus, the opening is at the very top of the cooking chamber so all of the hot air is just pouring right out before I can get any heat built up.

So, my idea to fix the problem is to put a sheet of stainless in the chimney and stick some pipes in it that are sticking down into the cooking chamber (See attached pic).

My hopes are that the hot air will rise to the top and stay in the cooking chamber and the relativley cooler air will be what leaves since the exhaust openings are low.

My big question is ... what size pipe should I use? Obviously, the opening was too big before. I don't want to make the mistake of making the new openings too small.

Anyone know of any good rules of thumb or calculations for sizing the exhaust?

45420

D.F. Expat
09-20-2010, 09:26 AM
Any room for a ball valve on the pipe?

S-L-A-C-K-E-R
09-20-2010, 09:33 AM
Any room for a ball valve on the pipe?

That's a really good idea. I was thinking of putting a damper on the end of the pipe somehow. I didn't even think of just putting a valve in the pipe. There should probably be enough room. I'm going to look into it. :thumb:

S-L-A-C-K-E-R
09-20-2010, 10:13 AM
Any room for a ball valve on the pipe?

well. it looks like I could fit one. but they are a bit expensive. So, I'm not sure if that's going to work.

Lake Dogs
09-20-2010, 01:49 PM
I'm thinking a damper will do it, both to regulate the temperature as well as the smoke.

Honestly, a piece of 3/4" plywood cut to a little bigger than the opening should do
nicely. With the opening that large, you'll probably never open it up past 1/2 way...