Do you know what the BTU rating is? They range widely and without knoing that it's impossible to say what you'll be able to do with it. In any event any coal stove that works well is going to save you money.
There's two types of coal appliances, stokers and hand fired units. Hand fired would be the type you are looking at. A stoker is automatic self feeding.
Within stokers there is two subsets. Hot air and boilers. Generally the hot air are smaller like Leisure Lines products. http://www.leisurelinestoves.com/698400.html
Lastly you have the "big dogs" which are boilers made by EFM, Keystoker and a few others. These are intended for whole house heating. Price varies and it's not cheap. At least $6000 and probably more than that. It's a lifetime investment though and well worth it if you want to go that route. It WILL outlast you.
Here's ours, 25 years old, runs 24/7/365 and isn't stopping any time soon.