tried the combustioneer 77 a few days ago just to play with it. Changed oil in transmission and hooked up. Started fire and was leaning on stove checking things out and kept feeling a small tingle. Got out meter and was getting 48 volts off of it. Power cord wasnt the greatest so replaced it next day and now much better, I can read 80 volts to ground ...haha So obviously I am going to rewire it completely now. I was also getting alot of smoke back in the hopper , which I understand is a problem when low on coal, but for now I have rolled it back off of the lauchpad and going to completely rebuild before the next fire. As for the big unit, it will be a summer install with new chimney and coal cellar. Thanks for asking Ill keep you updated! Hopefully by next year I will be one of the elite coal only burners!