I went to my local coal yard about 3miles from my home and got 100lbs of nut coal for free to try out. That was the biggest they had so since it was free decided why not, right? Anyhow today I threw in about half of a 5gal bucket in on a hot bed of coals and let it be. Now I had a few small pcs of wood left in there from lastnight. This was around 1pm, I went out tonight before work around 8pm and the coal was pretty much burnt up. I thought it would have lasted longer? Well I added about the same amount tonight and filled the firebox about 1/3 to MAYBE half the way up with wood. Im hoping to see some good results with this. Coal is really cheap around me. I can get 1 scoop which is 800lbs for about $20! Thats nut coal. I will continue to tinker with it and load more and more each time. I have my temp set at 180 with a 5 degree diff. If it stays cold enough I will have more time to play. But if it works I will be taking my dump truck and getting me a ton and mixing from here on out as long as I still live in this house.