A friend at work has built his own smoker. He is having some issues getting it up to temp and I told him I knew right where to go to ask what he needs to do. I guess you would call it a RF - someone can tell me if I posted this in the wrong section. He was holding 225 the other night but couldn't get it above that - from looking at it and knowing what I know I think his exhaust in his cook chamber is too small. I may be wrong but please look at my pitiful drawing below for what he has. Is there a calculator for a build somewhere that I can refer him to? Thanks in advance!