You are both right Tomturbomatic and Laundress regarding coal burning. Coal is still available here, mostly in 50 lb. bags or by bulk but it is screened, washed and oil treated, so there is no black dust, and not that cheap. Anthricite is the preferred coal as Bituminous is stinky and smoky. I am guessing the smoke/gas is nowhere as warm as wood, thats why it will not go up the chimney unless its cold outside. My coal stove's smoke pipe was always cool to the touch, all the heat radiated from the bottom so there was no danger of a chimney fire. Most of the old gravity furnaces were either one big outlet or several smaller ducts coming from the top of huge thing that looked like a gigantic tin can going to all directions in the house, thus the octopus. Many people did replace the coal grates with an oil or gas burner, but it was terribly inefficient. The new thing around here is a pellet stove. There are several factories that take the wood waste from sawmills and compress them into small pellets, think rabbit food, only bigger. These stoves are direct vented thru a wall, produce a ton of heat, are very efficient and the pellets are cheap. But they require electricity, so no power, no heat. Before my grandfather retired from the railroad, he bought a couple of the caboose pot bellied coal stoves (I have one in storage) before they swapped to kerosene. So I always will have another option. The only electric with a side heater I ever remembered seeing was my aunts Magee. I never had a clue Frigidaire ever made them.