A refrigerant circuit heat pump system selectively operable in each of an air cooling only mode, an air heating only mode, a liquid heating only mode, a combined air cooling and liquid heating mode, and a combined air heating and liquid heating mode, comprising:
- a refrigerant compressor having a suction port and a discharge port;
- a selectively positionable reversing valve having a first port, a second port, a third port and a fourth port, said reversing valve being positionable in a first position for coupling the first port and the second port in fluid flow communication and the third port and the fourth port in fluid flow communication, said reversing valve being positionable in a second position for coupling the first port and the third port in fluid flow communication and the second port and the fourth port in fluid flow communication;
- a refrigerant circuit providing a closed loop refrigerant circulation flow path, said refrigerant circuit having a first refrigerant line establishing a flow path between the discharge port of said compressor and the first port of said reversing valve, a second refrigerant line establishing a flow path between the second port of said reversing valve and the third port of said reversing valve, and a third refrigerant line establishing a flow path between the fourth port of said reversing valve and the suction port of said compressor;
- an outdoor heat exchanger operatively associated with the second refrigerant line and adapted for passing refrigerant through the second refrigerant line in heat exchange relationship with ambient air;
- an indoor heat exchanger operatively associated with the second refrigerant line and adapted for passing refrigerant through the second refrigerant line in heat exchange relationship with the air from a comfort zone, said indoor heat exchanger disposed downstream of said outdoor exchanger with respect to refrigerant flow in the air cooling only mode and upstream of the outdoor heat exchanger with respect to refrigerant flow through the second refrigerant line in the air heating only mode;
- a refrigerant to liquid heat exchanger operatively associated with the first refrigerant line and adapted for passing refrigerant through the first refrigerant line in heat exchange relationship with a liquid;
- a selectively positionable refrigerant to liquid heat exchanger bypass valve operatively associated with the first refrigerant line, said refrigerant to liquid heat exchanger bypass valve having a first position wherein said refrigerant passing through the first refrigerant line from said compressor is directed to the first port of said reversing valve without passing through said refrigerant to liquid heat exchanger and a second position wherein said refrigerant passing through the first refrigerant line from said compressor is directed through said refrigerant to liquid heat exchanger prior to passing to the first port of said reversing valve;
- an outdoor heat exchanger bypass valve operatively associated with the second refrigerant line at a location upstream of said outdoor heat exchanger with respect to refrigerant flow when said heat pump system is operating in the air cooling only mode, said outdoor heat exchanger bypass valve having a first position wherein said refrigerant passing through the second refrigerant line from the second port of said reversing valve is directed to pass through said outdoor heat exchanger and a second position wherein said refrigerant passing through the second refrigerant line from the second port of said reversing valve is directed to bypass said outdoor heat exchanger;
- an indoor heat exchanger bypass valve operatively associated with the second refrigerant line at a location upstream of said indoor heat exchanger with respect to refrigerant flow when said heat pump system is operating in the air heating only mode, said indoor heat exchanger bypass valve having a first position wherein said refrigerant passing through the second refrigerant line from the third port of said reversing valve is directed to pass through said indoor heat exchanger and a second position wherein said refrigerant passing through the second refrigerant line from the third port of said reversing valve is directed to bypass said indoor heat exchanger;
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- a suction line bypass circuit for directing refrigerant flow from said indoor heat exchanger bypass valve to said indoor heat exchanger when said heat pump system is operating in the combined air heating and liquid heating mode.