I am switching to a propane heat source, and have a 5-year old Harman PF100 Pellet Pro Furnace that burns wood pellets, with heating capacity of 2,500 sq. ft. and BTU range to 112,000 BTU. Features automatic ignition, total automatic operation with wall mounted temperature control. Extra large ash pan allows 2 to 3 tons of pellets to be burned before emptying. Dual heat exchangers. Can be installed as a stand-alone hot air heating system or incorporated into existing hot air systems. Direct vent system can use outside air for combustion, chimney not required