I've read most of this thread. I built a standard, basic UDS with a ball vale on bottom and flat lid w/ 3/4" holes in top. My fire basket is 13.5" round an my grate is 24" above. No water pan or defuser or anything fancy. I need to post pictures, but haven't gotten around to it yet.
I've read over and over that the outside of the drum is ~30* hotter than the middle. Well, after my first pork butt took way too long to cook, I checked my Spicewine and Maverick thermometer in boiling water. Both were dead on 212*. Tonight I did a fatty. The Spicewine on the side, about 1" below the grate was nearly exactly the same to 5* hotter than the Maverick was reading in the middle of the grate stuck in a potato about 1/2" above the grate.
I'm more than happy with this results. I'm just trying to get an correlation between the side and the center, so I can stop worrying about the thermometer in the middle. But, I'm left scratching my head since its almost a scientific law that the middle is hotter. Maybe I'm just lucky?
Proudly Smoking on a UDS, PBC &
Accidental Winner of the 2012 "Saucy" Throwdown.