You do have over fire air which is bled off from the primary air through those two gaps front and back. That is probably why there is a need to supply more primary air to get enough heat.larryfoster wrote:I have no over fire air all day, BTW.
Only under fire
The best way would be to close those gaps and supply secondary air separately as Lightning and KY speedracer have done.
Once volatiles have been burnt off a fan will only make things worse as it calls for heat and blows over the bed of coals and just cools things off. The coke remaining needs under fire air at that point.