How much lit charcoal are you starting with? I had this same issue in one of non-insulated verticals. I start with more lit coals and I don't have this problem anymore. Don't worry about the cold air from the intake because the hot air should rise not the cold air. Just my .02 but I have never built a smoker so I may not even know what I am talking about... Also, try without the heat diverter. I was told that it was only really necessary if you were cooking hot and fast to help you from having to add water all the time.
Shirley Fabrication (on order)
Abe's Smokers 48" Entertainer
Custom 20x52 vertical
Texas Smokemaster offset
Brinkmann Mini WSM
Jimmy (jumbo mini)
Thermopop & Thermapen (both red)
HeaterMeter with Roto Damper & blower, Maverick ET-732 (x2)
Last edited by pjtexas1; 03-02-2014 at 04:20 PM..
Reason: more questions