When I posted photos of my UDS with the extended air intake (page 18 of this forum) I had no idea that so many people would be giving it a try. I was toying with a theory about air flow (I really got enthused about it when I saw a video featuring the Slow Snail cooking team using smokers along this same principal), draft is draft regardless where it comes from. Due to problems with my back I have a problem bending from time to time so I was looking for something easier and to make using the smoker a little more fun.
You must have intake and exhaust to acheive combustion, the amount of heat depends on the amount of air flow, notice that the orginal BDS and UDS clones has multiple air inlets at the bottom while my verticle air intake is singular, however a potential problem with some of the smokers being made with this design that are not being able to keep temps regulated is that they may not have a sufficent size air inlet. The reason I went with the 2" exhaust tubing is you need to be able to match the flow capability of the combined air inlets used on the BDS & UDS clone smokers that have 3 or 4 valves mounted at the bottom. You simply can't move the same amount of air thru a single upright tube that is the same size as only one of the bottom inlet tubes. To match that capability you must either have the same number of inlets that are the same size or 1 large inlet capable of flowing the combined amount of air. I have 4 of these smokers and they all work really well, all have 2" inlets and the exhaust are 2 1/2", I can set the temps at 215 or 350 and it will hold for hours.
One of the key secrets is to make sure that all other air sources are closed, use a small hammer and fit the lid to the barrell so it fits securely.
The verticle intake creates more of a bellows effect by having a large volume of cool air confined in the intake tube thus forcing it into the bottom of the smoker. Once adjusted you can place you little finger in the opening of the inlet tube and feel the air flowing as its being drawn into the smoking chamber. I made one for a co-worker and he loves it, I gave one to my Father for Christmas and at 76 years old he's smoking ribs, bologna, and shoulders every couple of weeks. So if your having trouble getting temps up or stabilized you may want to evaluate your inlet tube size.
I must agree with N8man try to catch your temps on the way up, it takes too long sometimes for the temps to drop back to where you want it.
custom made mobile offset smoker
1 modified double barrel smoker
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