gitcodered,Welcome to the forum where you can get an answer to any coal burning question. I read your post late last night,i either have a very thick skull or a brain stuck in slow gear,i just reread your post & believe you might have answered your own question. You state that the fire won't get hot enough with "ALL THAT ASH"from 24 hrs,coal likes a hot fire,lots of air from below the grates,& lots of coal above.Try a vigorous shaking every 12 hrs. ,watch for ash pan to glow ,load lots of fresh coal on top of strong fire.Stove size vs. nut size,stove will burn quicker as more air is getting thru,but will burn up quicker too.Nut will slow the fire down,giving a longer consistent fire,just make sure going from wood to coal that you close the air dampers in the door & only have the below grate air open.Some coal burning experts will be along to guide you further on your coal burning adventure.By the way this stove does have shaker grates ?? as coal does not like to be disturbed too much from above.