First fire, efficiency is so great
I add 2" lining by ceramic clay on the bottom( not walls) this afternoon.
I bought much less clay than needed for walls
The clay was still wet and I lighted the pit at 13:45.
I used my controller of Golden-Tiger with 50 CFM fan.
First I used manual mode. In 10 minutes it reached to 160C(320F)
Then I turned it to automatic control and set target pit temperature at 150C(302F).It fluctuated a while and then stayed at 155C(311F).
At 16:00 I turned it to manual mode by mistake and when I found it and the pit reached to 190C (374F). I turned it to automatic again and changed target to 105C(221F). It droped to 105C around 17:30. and then kept at 105C, occassionally 104C. It is 23:30 now and it is still 105C.
I put in about 2 lbs charcoal(lump).
It is too late and I do not know how much charcoal is left.
I will leave it there and go to bed.
But one thing is clear, 2 lbs keeps the pit at >105C for 9.5 hours already.
and must be longer, I will lose final data.