Abstract: A heating system having buried, outwardly directed loops through which freon is routed for partaking of ground heat. The buried loops are inclined downwardly from an expansion valve and distributor with the loops each discharging into a central collector from where the freon vapor is directed to a liquid trap and thence a compressor. A medium-to-air heat exchanger is located in a cold air duct. A receiver tank stores liquid freon and supplies in a constant manner to the expansion valve.