I had a smokehouse burn one time. Classic stack fire it was loud and hot. Burned up about 100 lbs of king strips and for me it was a huge loss. Not the smoker but the fish. I now clean the pipe a couple times a year.
Cleaning the stack and insides is always a good idea, especially if your smoker was built by an Einstein who put the stack in the middle of the top!!! Never put the stack in the top of the smoker!
It acts like a reflux still and condensation in the stack falls back on your product! YUCK!!!!!!!!!!!!!!!!!!! Or you end up with tin foil boats to catch it and that wastes space and gives the opportunity to spill that wonderful essence... the same one Wright's puts in a bottle and sells to the incredibly gullible. YUCK again...
The stack should come out of the back very near the top! A trap with a drain is a very good idea.
