Originally Posted by SmokeMaster85
I Build smokers for a living an your stack should be 1/3 of the length of the smoker , and the diameter should be 20% of the tank diameter.
I am not sure that would hold true for every situation. Your smokers are probably very good and that holds true for your design but there may be some exceptions. For example my Oklahoma Joe has a Chamber/tank length of 35" and the diameter is 17", so the stack should be 11.6" x 5.25"?? The above referenced calculator says my stack should be 25.7" x 3". The stack on mine is actually 17" x 3". It works great. But I may add some length to get the smoke away from the face like Lightfoot did to his.
The thing about smoke and heat is that it rises. So if your stack is 10" or 30" in length it shouldn't make that much of a difference at the temperatures we usually smoke at. However, I believe the diameter does make a difference in the amount or volume of smoke that is allowed to escape the chamber. The baffle is used to regulate how much volume you want to allow to escape. ie. changing the diameter of the pipe end. Obviously if your stack is to small in diameter you will have issues. A 2" dia. stack would not be good. I think that the diameter probably should be around 15% the dia. of the tank.
With that said, the damper or baffle, as we all know, is also used to control the heat. The fire chamber needs air to burn the fuel so the baffle there is used to regulate the air intake thus the temperature. So the two work in tandem to control the heat and the length of time the smoke stays in the chamber.
I personally don't believe the length of the stack really makes that much of a difference. The diameter is what determines the amount of smoke and heat released. The temp control is critical and I find that the fire box baffle is the primary way to control that. However, if you completely close the stack baffle you won't have air flow and your fire will die eventually.
The real secret to a great smoke is to know your smoker and learn what it takes to get the results you want. A few mods can mean the difference between great meat and outstanding meat. In my humble, uneducated opinion, the science is simple. Heat and smoke want to go up and they will find a way to do that. Determine the route and velocity you want to allow that heat and smoke to take and put your meat in its path.
That is just my 2 cents worth and about all it's worth.
Edited by Doyne - 6/4/14 at 8:00am