Here is the way I start my UDS using RO lump. I have an elcheapo brand chimney starter & only have about two layers of charcoal covering the bottom. I start it using the side burner on my gas grill. When it is all burning, I pour it in the center of the unlit charcoal in my basket & lower it into my UDS. I then put my grates in place & close the lid. I have all 3 of my 3/4" bottom vents open. When my internal temp hits around 180*, I cap one vent. At 200*, I cap the second. At 220*, I close the ball valve about half & it will settle in between 240-250*. At 250*, I only have the ball valve open between 1/4-1/2 depending on wind, temp, etc. Once temps over shoot your target point & your fire mass gets too big, it is hard to bring the temps back down. Also, my drum reacts very slowly to changes in vent settings, so be sure to give it 15-25 mins after opening/closing a vent to be sure what the final effect will be.
A leaky lid can be a problem. I had leaks around my lid & would see temps creep up during a long cook. I could close all bottom vents & still run 230*. Try loosely rolling some heavy duty foil & place it around the lip of your drum. Put your lid on slowly & press down gently. This will help seal most of the air leaks around your lid & let you know if that is a problem or not.
Jim Sewell -- GBA Vice President, Master Judge, Contest Rep & GBA Webmaster