Patent ID: 8056348

Claim:
A method for controlling refrigerant charge in a reversible heat pump having a closed loop refrigerant circulation circuit and a refrigerant reservoir in operative association with said refrigerant circulation circuit for storing a volume of refrigerant, the heat pump operable in an air cooling only mode, an air heating only mode, an auxiliary water heating only mode, a combined air cooling and auxiliary water heating mode, and a combined air heating and auxiliary water heating mode; said method comprising the steps of: upon initiating operation in one of said modes, adjusting the initial volume of refrigerant in said refrigerant reservoir to a desired initial volume for said one of said modes, wherein if said one of said modes is a mode without water heating, selectively directing refrigerant in a liquid state from said refrigerant circulation circuit into said refrigerant reservoir to fill said refrigerant reservoir with liquid refrigerant, and wherein if said one of said modes is a mode with water heating, selectively directing refrigerant in a gaseous state from said refrigerant circulation circuit into said refrigerant reservoir to fill said refrigerant reservoir with gaseous refrigerant; sensing the compressor discharge temperature during operation in said one of said modes; comparing the sensed compressor discharge temperature to a preselected upper limit for compressor discharge temperature; if the sensed compressor discharge temperature exceeds the preselected upper limit for compressor discharge temperature, directing liquid refrigerant from said refrigeration reservoir into said refrigeration circulation circuit.