No one has a coal furnace in their home
Not my concern if they don’t want to burn a little coal to stay affordably warm in the winter. Perhaps they are two lazy to keep it stoked and the ashes cleaned.
Tractor Supply has several models from which to choose, starting at about $800.
http://www.tractorsupply.com/en/store/united-states-stove-wonderluxe-wood-coal-stove
Heat a standard suburban home about $1400
http://www.tractorsupply.com/en/store/united-states-stove-hot-blast-warm-air-furnace-2500-sq-ft
Or a 3000 sq ft home or business for under $2400.
http://www.tractorsupply.com/en/store/united-states-stove-multifuel-furnace