I used google to see what methods the pros used. It boiled down to 2 principles= Reverse circulation and heat retention. A lot of people will tell you about controlling the air with inlet and outlet dampers and using gas to supplement the coals.But it is all a workaround for a piss poor design.
Originally Posted by hurtinhvac
Use the reverse circulation design with thick metal and you will have a super smoker.
Google "reverse flow smoker", and remember the thicker the metal the more heat it will retain. Stay away from 50 gallon barrel type designs.
Some Talk, Some Do
"keeping condensing pressures low and evaporator pressures high"
"Some customers are more interested in comfort than energy savings"