Abstract: A direct expansion ground source heat pump operable in heating mode and cooling mode. The heat pump comprises an outdoor coil, an indoor coil and a compressor. The outdoor coil and the indoor coil are coupled to the compressor through a reversing valve and the compressor provides a refrigerant flow through the coils. The indoor coil and outdoor coil are coupled together through a controllable valve. The outdoor coil comprises two coil circuits. In heating mode both ground coil circuits are active, while in cooling mode, the heat pump utilizes one of the coil circuits and alternates between coil circuits each compressor cycle.

Abstract: A ground source heat pump comprising an indoor coil circuit and an outdoor coil circuit utilizes a scroll compressor to pressurize the refrigerant. The outdoor coil may comprise ground coils formed from copper tubing into a spiral configuration. A charge control device controls the volume of refrigerant in the system in heating and cooling modes. A restrictor in parallel with a thermal expansion valve permits a base flow of refrigerant into the outdoor coil in heating mode. An accumulator is provided with a level switch controlling a solenoide value connected in parallel to a thermal expansion value feedig the indoor coil. The scroll compressor includes a discharge port operating in conjunction with a solenoid valve to trap high pressure refrigerant in the condenser circuit during compressor off cycles. Means for closing off one of the ground coils to reduce the effective length of the outdoor coil is provided.