Built first fire in smoker today. It is a horizontal with a vertical. My temp are about 100 degrees different. Any suggestions??? I can get my horizontal to 500 no problem but vertical is about 200 then. I'm thinking that my exhaust is not large enough. The fire box opening is a 5 1/2 " opening, I used the calculator to figure opening between FB and CC. Used same opening for CC to vertical. I have a 3" exhaust. Any suggestions will be greatly appreciates