I am new to smoking. I just made an UDS. I am having trouble keeping the heat in the smoking range. I have 3 1" hole drilled in the bottom with 2 caps and the other one with a ball valve. for the top I am using a Weber dome cover from a 22.5 inch grill. I have been using the minion method for lighting the charcoal. Once the UDS is up to temp.225 I close all the vents and the temp continues to rise. Please help.