We have been doing some summer testing on our stoves. I have found that with the coal trol turned to 4 on the min., we burn about 6oz. of coal per hr. We have turned the min to 3 and burnt just over 4oz per hr. That's a great savings. Burn 24 hrs. on 9lbs of coal. Naturally, the min will vary because of different coal. At our shop we can burn on 3 and hold a fire, at our retail store (different coal) we need the setting at 5 or we will loose the fire.
Jerry