Smoke coming out of stone barbeque no draft

[newimaging]

After building the pizza oven, and having great success, we put together this stone barbeque. The smoker part on the right side works perfect, as the chimney has good draft. The barbeque itself however has a small hole in the center with probably 6 feet of rise on a chimney pipe, but I think the hole and pipe is just to small to handle all the smoke when fat drips.
Do you guys think I should knock out some bricks in the back and build up a bigger chimney ? Is there a formula on how big the chimney has to be ?
Thanks for any ideas.

Christian

[newimaging]

So I added a new chimney to the back side of it now, knocked out some bricks, but still have smoke coming out the front. Now I`ll try to add some hight to it I guess.
I haven`t seen any barbeques yet that have a cover over it.

[Nic The Landscaper]

I think your smoke issue is coming from the lack of a smoke chamber or area for the smoke to collect. The smoke chamber also defines the volume that the vacuum of the flue acts upon. So if you add a dropped lip or step along the front edge of your brick arch this will create your smoke chamber.

In terms of flue/chimney sizing there are minimum standards for fireplaces that should work for your situation. A flue opening should be a minimum of 15% of the opening of your fireplace. So lets say your opening is 3' x 3' or 9 square feet. 15% of 9 square is 1.35 square feet which is 1.15' x 1.15'. multiply this by 12" and it tells you what your minimum nominal inside dimension is for optimal draw. that dimension is about 14" by 14". a 12"x18" flue would also get you pretty close to this same ratio. The height is so variable depending on region elevation etc that it is difficult to really discuss. A minimum for a fireplace area the size we are discussing is really about 5 to 6 feet and will always extend at least 24" above any surrounding combustibles.

Hope this helps a little.

[neilsteven11]

Cleaning the smoke chamber on your chimney is fairly straightforward. I think your burner is not adjusted correctly. You need to have the crack repaired by a qualified mason.

[newimaging]

I tore the old chimney back off, made the whole a lot bigger and will build a larger one now based on your formula, I also made the opening in the front a lot smaller as you can tell by the pictures, and closed the arc on the top. I just got married this weekend, so had to take a short break from cement work will let you know once its done. Here is a temp picture.

[Nic The Landscaper]

Wow!! I think that looks way cooler now and I bet it will pump that smoke out of there!!