I can load good dry wood on hot bed of coals and shut the air completely down all the way. Yes for a few minutes the stove sits there and does nothing. I can come back later and the stove is roaring with the air complete shut and stove top temps are in the 700 to 800 range. I am thinking this is because with the air shut down all the way allows the stove to heat up easier with the hot coal bed. If the air is wide open or the door is cracked the air flow is much greater in the stove making it harder for heat to come up in the stove. With air shut the coals will heat the wood up and eventually take off and once it takes off the heat comes up in the stove very fast because there is such low air flow thru the stove. As wood burning is about the heat in the stove. I think we look more at burning causes heat but a better way to focus on it is the heat will allow the wood to burn as once the off gasing starts from the wood being heated up the burning will take off really fast. As the hot coal bed will be the source of the heat at the input air setting being completely closed and very little air flow allowing that coal bed to heat the wood much better.