Patent ID: 8402780
Filing Date: 2013-03-26
Classification: F25B

Abstract:
1. A direct exchange geothermal heat pump system comprising: refrigerant tubing including a liquid tubing coupled to a vapor tubing, a sub-surface portion of the liquid tubing together with a sub-surface portion of the vapor tubing defining an exterior geothermal heat exchanger; a refrigerant disposed in the refrigerant tubing and having a refrigerant weight; a first compressor having a first compressor suction line fluidly communicating with the refrigerant tubing and a first compressor discharge line; an interior heat exchanger disposed in the refrigerant tubing and having a first end fluidly communicating with first compressor discharge line and a second end fluidly communicating with the exterior geothermal heat exchanger; an initial oil charge equal to a factory recommended volume of oil for the first compressor; and an extra oil charge having a weight of at least 7% of the refrigerant weight.