I wondered if the amount of steam being generated from a pan in a Kamado is enough to even make a difference to the air pressure beyond the expansion of gases due to burning the charcoal.
Does anyone have any idea how to test this or has this already been done?
OK, so I did some digging....
With the Classic II, I typically can fill the fire box with about 5 lbs of charcoal. 5 lbs of coal generates roughly 10 lbs of CO2. 1 lb of CO2 fits into a square of roughly 24.6". Therefore 5 lbs of lump produces 80 cubic feet of CO2. Since a 5 lb burn at 275 will generally take let's say 12-13 hours, the Kamado in theory should be throwing out 7 cubic feet/hour or 0.11 CFM of CO2 through a 1" square opening.
With these rates, I don't see why there should be any effective back pressure inside the Kamado due to steam since the top opening looks like it can easily handle the CFM. The flow is in reality higher due to the open vent at the bottom.
Sorry, hope I'm not rubbing anyone the wrong way, but my theory is that the heat rising out of the top vent is most likely pulling the pressure out of the Kamado faster than pressure can build in it unless the top is almost totally closed.