Originally Posted by HogFan
Diffusers will always be less efficient. On some cooks I use them and others I don't. I started out using a 16" perforated pizza pan but now I use a 14" solid pizza pan with 1/2" holes drilled in it. I used it on a 15lb brisket smoke for Thanksgiving. I don't yet have a 3rd rack to lay the diffuser on and haven't made any type of holder to keep the diffuser a couple of inches off the charcoal basket so I didn't quite fill the charcoal basket so the diffuser would lay flat on the basket. I opted for a low and slow overnight smoke after 16 hours, I ran out of fuel and the brisket wasn't quite done. I added fuel and the brisket still turned out fantastic.
So what was the difference using a diffuser? The temperature is more consistent from the center of the drum to the outside. The end of the flat seemed to get more heat and cooked more evenly with the point.
I have never found it to be "less efficient"...I have never noticed my UDS using more fuel with one than without, although I have never weighed the charcoal before and the leftover, and calculated lbs per hour or anything like that.
......but it does remove a lot of radiant heating from the equation