Starting a build with 250 gallon propane tank. Been working with Dave on this and has been a huge help, especially understanding the math and terminology parts. Here is what I have so far: Volume of the Cook Chamber.... Use the Inside Diameter of the tank... Diameter X Diameter X 0.7854 X Length = Volume in cubic inches / 231 = Volume in gallons 60147 / 260 Volume in cubic inches X 0.004 = FB/CC opening in square inches 240.58 Volume in cubic inches X 0.004 = Area under the RF plate in square inches 240.58 Volume in cubic inches X 0.004 = Area required at the end of the RF plate in square inches 240.58 Volume in cubic inches X 0.33 = minimum volume of the Fire Box 19848.51 Length of Tank 88" Diameter of Tank 30" Vol in CC 60147 FB-CC opening 241 FB Vol 19849 Air Intake 60 ESV 1316 Dia of Stack 7" ID x 34" stack Segment area 241 Segment height 11.5 FB size I'll make is 30hx30hx32d I know oversized and figure the deep ash drawer would lose some of it's "space". Otherwise should be good. Picking up a trailer 8x18 which I'll be building a roof and walls for "kitchen". Going to try for competition cooking as well as parties.