My folks have been running a DF520 since early 1980's with large coal bin, and they are considering selling the house in a year or so. The house is well insulated so they only burn 4 or less tons a year. They wanted to replace the boiler with a more efficient oil boiler for the sale of the house. Does having the DF520 (oil/coal) make it harder to sell a house in the Doylestown PA area? I told them we could sell the used DF520 if this was the option they preferred. Of course, if I move down there and buy the house I would keep it!