jeephammer has the right of things. Home in the dirt is easier to heat AND way easier to cool. When we built the cabin we put a Water Furnace in and I've been very satisfied with the efficiency. Excess heat from the condenser pre-heats the hot water and the coils are always sheltered from the outdoors and the attendant grime and pollutants. Been in the house 25 + years and replaced the first unit at about 16 yrs. Compared to propane/outdoor heat pump, it has paid for itself several times.