how big of a fire box will I need for 110 gallon smoker welding two 55 drums together at the open ends and how big of a chimney will I need thought about going 3 inch exhaust pipe or 4 inch and how long of a chimney will I need for good air flow for an conventional offset smoker would like to use a round fire box to Match barrel thought about useing a 30 gallon grease barrel or cut a 55 down
