Sounds like a fascinating system to develop! What are the details of your grandmother's house? Sq. Ft., floor plan, how many floors, age, insulation, windows, etc.
Just FYI, Willburt Mfg. still makes a residential coal stoker for bituminous.
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. It might be a little big, depending on the size of the house. You'd also have to find a boiler to stick it in. That would be a lot of work, but could be really neat.
We live up by Rockford, IL. Our house is new, well insulated, and about 2800 sq.ft. Pretty easy to heat with our 90%+ natural gas hot air. I just HATE hot air, though. Got spoiled years ago living on the east coast with hot water and steam heated homes. My grand plan is to custom build a home one of these years with multiple zone hot water combined with a dedicated, properly engineered A/C system for the summer. Trying to cool a 2 story house in the summer by using the heat ductwork is an excercise in futility.
I'm trying to figure out a good way to install a stove, and convince the wife that the gas fireplace we have would really look better with a stove plugged into it. It's not working so far....
The other side of the issue is anthracite is $$$ here ($300/ton bagged Blaschak). I can get Illinois bituminous for $88/ton down by Peoria, but nothing will burn it well enough until someone comes out with a small stoker (like the current crop of anthracite stoker stoves). I hear one is being developed by anthracite stove company here, but a year or two away yet.
Too bad they quit making the Warm Morning heaters. Lots of them in Indiana when I was young. They burn that cr*p coal pretty well.