Thank you again for the quick reply, but I'm still a bit mystified and have a couple questions.
1. I control the dampers, so why does the lower vent need to be so much larger than the higher vent? What is the effect on the air flow that I am trying to create with this 80/20 split that I cannot otherwise control with dampers?
When folks used a calculator that is on the web, some had FB that got extremely hot while the CC didn't get hot.... The FB air inlet was split so the upper air inlet could move "heat/smoke" from the FB to the CC WITHOUT adding air to the fire... That solved their problems... an inlet to adjust the heat of the fire and an air inlet to add air flow to the smoker without adding additional heat... ALSO, the FB/CC opening was enlarged to allow for better air flow...
2. Is the total area of the vents the maximum or minimum size needed to allow for efficient air flow?
The numbers seem to work satisfactorily as they are... Since the air inlets are adjustable, it really makes no difference on the size you start with because they don't end up there... The numbers are a very good compromise for building a great smoker...
3. Is the ratio of width to height of the vents significant? Example, at 80% my lower vent has to be 21" (and some change), should I proceed with a 7" x 3" vent, or is there a ratio like 3:1 I should be targeting?
The lower air inlets work best when installed below the wood grate in the FB... 5-6" if space under the grate works well... more if you want... less, not so desirable.... not enough ash storage....
And again, thank you for the instructions, links, and answers you have provided. You have already saved my smoker from being a complete disaster!
The numbers have been calculated and tested by members for years... Periodically an improvement will come along and the tutorial is adjusted to reflect the improvement...
The tutorial is not perfect... numbers can be tweaked as folks wish... The basic smoker works very well....
