Just a line here quick if its any help.
If you bought coal from us this year chances are it is South Tamaqua area coal.....depending when you bought it. Right now that is what Im burning in my EFM and I am set at 4 feed and 4.75 or so on the air. I was at 4 and a half air for awhile but I was still getting unburnt coal.
Right now I dont think I can get the ash any better. Once in a while I can find a small piece of unburnt coal.... but I really have to dig around to find it.
My fire always seems to have a very nicely formed ring on it.... gets even better when it fires harder.
Thats been my expirience anyhow if it helps.