Questions about stack placement

[fefish]

Made 120 gallon reverse flow about 2 years ago, and have finally used it enough to start to wrap my head around it. As you can see from the picture, the stack comes off even with the bottom rack. I did this because the bottom rack was most important to me at the time, and I heard a well respected pit builder put his there. However, as many of you already know, the top rack is 50 or so degrees hotter than the bottom rack. The builder I’m talking about doesn’t use multiple racks though.

I have several questions about this, if you can indulge me.

If I add a stack near the top, will that make the entire cooking chamber identical temperature throughout?

How far up near the top should I put it?

Should the stack extend down into the chamber at all?

Would there be any conceivable reason or benefit to leaving the stack in the side and adding the one in the top and having dual exhausts(other than the obvious hp gain, and good sound)? Would I be able to throttle them to make the temperature even throughout?

Any thoughts or ideas are greatly appreciated. I’m really curious to find out the little nuances and any detailed info that may accompany your method or reasoning. Thanks

Smoker 1.jpg

• fefish
• Sep 6, 2017

 

[daveomak]

I looked for your "smoker build" thread and couldn't find one....

Looks to me like the FB/CC opening is too small... poor air flow causes very high temps in the FB with little air going to the CC...
The exhaust stack should have been installed into a plenum that was between the upper and lower cooking racks.....

A upper air inlet, above the door to the FB, would certainly help.. The inlets to the FB do much better if they are holes with a slide damper, like below....



Check your build against the numbers in this tutorial....

https://www.smokingmeatforums.com/t...eady-to-use-rev5-6-19-15.172425/#post_1264161

.....

 

[fefish]

Thanks for super quick reply Dave! I’ll check the numbers tomorrow versus what I have.

As far as the upper air inlet goes, I don’t actually “smoke”, I burn clean fire with both fire box doors wide open. Does that count as having upper air inlet or do I need to put more holes in the top of the firebox too? Thanks

 

[daveomak]

With both doors open indicates there is a design problem... You have no fire control or temp control with both or any doors open... Your smoker should be air tight... no air leaks, and controlled using the air inlets...
Woody G seems happy with how the numbers work... Check out his build thead....
https://www.smokingmeatforums.com/threads/short-fat-120-gallon-build.238321/page-7#post-1641495