Question: Does having a large smoker mean you need ALOT of charcoal to heat it

If building a horizontal with side fire box, the size of the smoke chamber will be the main factor in how large of a fire it will take to heat it, along with efficiency of the overall design. Also, if you're building a standard horizontal, you'll need to add baffle/tuning plates to reduce cooking grate temperature variations. If you build a reverse flow, they give the most evenly heated smoke chamber/cooking grate.

If you haven'y already looked at the smoker build forums, I would suggest you check them out, as there are tons of very good build projects posted there:

Horizontal Reverse Flow Smokers

Horizontal Side Fire Box

If you like to tend a charcoal fire for smoking a pork butt,  beef chuck and other bulked-up cuts, but don't smoke ribs, brisket or other cuts with a large foot-print, then an inexpensive factory built vertical smoker may be the route to go, as they burn far less charcoal than a horizontal. My Brinkmann SNP 40" horizontal is capable of burning 2-3lbs/hr while my Brinkmann Gourmet vertical burns 1/2-2/3lb/hr in similar conditions. For economical use, verticals are the way to go, but they require some tricks when smoking relatively large cuts of meat like a 14 lb whole beef rib.

Good luck, great smokes!

Eric

Yeah i belive you will use more fuel. I use alot more lump in my chargriller than i do my ecb,your trying to heat a much larger space so you will need more heat to get the temp up and to keep it there.

the thickness of the steel will play a big part, a 20 x 48 in 14 gauge sheetmetal is gonna use more fuel than 20 x 48 in 1/4 inch steel pipe, with wind and colder temps the spread widens.

20 x 60 is big enough I would do a square firebox out of the thickest steel I could afford and or work with and just build it intending to burn wood and not use charcoal much at all.

Reverse flows are notorious fuel hogs, especailly if your water crutching it, IMO a good portion of the heat is just bringing the pit up to temp, once that metal gets hot you use less fuel to stay there, I would suspect the difference may be two or three lbs of charcoal to get up to temp but little or nothing to maintain if its nice thick steel.

if you have the ability to work with 1/2 go for it, usually the cost of steel ain't the problem its the weight, 1/4 steel is what most people consider a heavy gauge pit so anything thicker than that is a plus, these are usually the pits that even if neglected will last 30 years, with a little care they will last a lifetime. Obviously whatever you decide on the chamber size will dictate the size of the firebox, 20 x 20 on a 60 x 20 sounds good to me but I'm a pit buyer not a pit builder LOL. My pit is 24 x 54 with 24 x 24 side fire box, both my chamber and pipe are round like a tradional offset, a 20 x 20 sqaure firebox has more volume than a 20 x 20 round sfb so that might be overkill. There are alot of pit builder programs and stuff out there to check out to make sure you get all the sizing, the chamber size will give you a ballpark for firebox size and them two will give you an idea of exhaust size etc.