I got my UDS put together over the weekend and I had to fire it up to see how it held temperature. When I fired it up, I used about a half a fire box of Cowboy lump, I used a half a starter full of Cowboy lump and pre-lit it with a oxy/acc torch until about half white. I then dumped the starter onto the top of the unlit coals in the basket, spreading them around the top evenly.
I put the top on and watched as the temp gauge started to climb, when the temp got to 180 degrees, I closed one intake vent with a cap. When the temp got to 200 degrees, I closed the other vent with a cap. When the temp got to 210 degrees, I closed the gate valve to half open.
The problem is that within 15 minutes I had 230-240 degrees and climbing fast, so I closed the ball valve all the way and watched as the temp continued to climb. It started climbing slower, but never did stop, my digital temp gauge went off the chart, and my analog gauge below the rack did the same. I figure they were both over 500 degrees with all vents closed.
HERE IS WHAT I HAVE:
Normal drum size,
3-3/4 inch vents 2 inches up from the bottom,
1 of the vents rises up the side 2 foot with a ball valve on the top,
1 three inch vent stack about 5 inches high out of the center of the top,
18 inch Weber charcoal rack with 8 inch expanded metal sides, and it sits 3 inches off the bottom of the barrel.
Top is an older off brand that is a Weber style but larger, it sits over the barrel sides by about 2 inches all the way around, I had no (or very little) smoke leaking from the fit around the top of the barrel and the top, the rubber seal I put on seemed to fit and seal well.
Any idea's on what is wrong, and why I can not keep the temps down? I am no expert, but I am guessing I lit too much charcoal in the starter, and it in turn lit too much of the Cowboy lump when I placed it in and spread it around?
Shouldn't the temps have gone down after closing all the vents? An hour after all vents were closed it was still pegging the needle of my turkey fryer gauge. I pulled the new digital out because I did not want to break it.