Firebox size and burn time
Thought I would chime in on the firebox size and burn time discussion. I build 12" tall by 14" diameter fireboxes for my UDS's. I did two 9 lbs. pork shoulders last weekend, and I started the UDS at 4:00pm.....it was still at temp (245 degrees F)at 7:00am the next morning. So, that's 15 hours. I pulled the pork, and let the cooker go for another hour, and then shut it down. So, that was 16 hours.
When I opened it up the next day to do a little cleanout.....I still had 3-4 inches of unburnt coals in the firebox.
I usually fill it up to about an inch from the top, and then make a small well in the middle. I usually put 12-15 glowing coals right in the center in about an 8-inch circle, with a couple 2-3 diameter wood chunks on the edge for smoke.