Integrated heat pump and water heating circuit

Abstract

An integrated heat pump and water heating circuit for space heating and cooling and heating domestic water. The circuit includes a first heat exchanger for the domestic water, a second heat exchanger for the source (heat source/sink) with a first dedicated expansion valve, and a third exchanger for the space with a second dedicated expansion valve. The circuit has four modes of operation. In the first mode, the space is cooled and heat is rejected to the source. In the second mode, the space is heated while heat is absorbed from the source. In the third mode, the circuit absorbs heat from the source and heats the water supply. In a fourth mode, the water supply is heated and the space is cooled simultaneously. In each mode, one heat exchanger is inactive, and the charge from the inactive heat exchanger is reclaimed to the suction side of the compressor.

What is claimed is: 
     
         1 . A heat pump and water heating circuit for a structure, wherein the structure has a heat pump source, a domestic water supply, and an space to be cooled and heated, the circuit comprising;
 a compressor having an inlet and an outlet;   a plurality of heat exchangers comprising:
 a first heat exchanger fluidly connectable to the structure's domestic water supply, the first heat exchanger operable as a condenser to heat the water supply; 
 a second heat exchanger fluidly connectable to the heat pump's source, the second heat exchanger being operable alternately as an evaporator and a condenser to selective reject heat to or absorb heat from the source; 
 a third heat exchanger fluidly connected to the space, the third heat exchanger being operable alternately as an evaporator and a condenser to selectively cool or heat the space; 
   a conduit assembly fluidly connecting the compressor and the plurality of heat exchangers to form a refrigerant circuit;   a first one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the second heat exchanger and only when the second heat exchanger is operating as an evaporator; and   a second one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the third heat exchanger and only when the third heat exchanger is operating as an evaporator; and   a valve assembly in the conduit assembly configured to direct refrigerant between the compressor and the heat exchangers selectively in four different paths to provide four operating modes including a first space-cooling-only mode, a second space-heating-only mode, a third water-heating-only mode, and a fourth mode in which the water supply is heated and the space is cooled simultaneously.   
     
     
         2 . The heat pump and water heating circuit of  claim 1  further comprising a desuperheater between the outlet of the compressor and the plurality of heat exchangers, wherein the desuperheater is fluidly connectable to the structure's domestic water supply. 
     
     
         3 . The heat pump and water heating circuit of  claim 1  wherein the each of the first and second expansion valves comprises an electronic expansion valve operable between a metering position in which refrigerant is metered into the heat exchanger and a closed position in which flow through the expansion valve is blocked, and wherein the valve assembly includes a check valve for each expansion valve configured to allow fluid to bypass the expansion valve. 
     
     
         4 . The heat pump and water heating circuit of  claim 1  wherein each of the first and second expansion valves comprises a mechanical expansion valve and a solenoid shut-off valve, and wherein the valve assembly includes a check valve for each expansion valve configured to allow fluid to bypass the expansion valve. 
     
     
         5 . The heat pump and water heating circuit of  claim 1  wherein the valve assembly comprises a diverting valve and a reversing valve. 
     
     
         6 . The heat pump and water heating circuit of  claim 1  wherein in any of the four modes of operation one of the plurality of heat exchangers is inactive and wherein the conduit assembly and the valve assembly are configured to direct refrigerant from the inactive heater exchanger to the suction side of the compressor whereby the charge from the inactive heater exchanger is reclaimed. 
     
     
         7 . The heat pump and water heating circuit of  claim 1  wherein the heat pump source is a water source. 
     
     
         8 . A method for providing air conditioning and water heating to a structure, wherein the structure has a heat pump source, a domestic water supply, and a space to be cooled and heated, the method comprising:
 selectively circulating refrigerant in a single refrigerant circuit, wherein the refrigerant circuit comprises a plurality of heat exchangers and a compressor interconnected by a conduit assembly, and wherein the circulating step includes directing refrigerant through four different fluid paths to provide four operating modes including a first space-cooling-only mode, a second space-heating-only mode, a third water-heating-only mode, and a fourth mode in which the domestic water supply is heated and the space is cooled simultaneously.   
     
     
         9 . The method of  claim 8  wherein the refrigerant circuit further comprises a desuperheater between the outlet of the compressor and the plurality of heat exchangers and wherein the desuperheater is fluidly connectable to the structure's water supply. 
     
     
         10 . The method of  claim 8  wherein the plurality of heat exchangers in the refrigerant circuit includes:
 a first heat exchanger fluidly connectable to the structure's domestic water supply, the first heat exchanger operable as a condenser to heat the water supply; 
 a second heat exchanger fluidly connectable to the heat pump's source, the second heat exchanger being operable alternately as an evaporator and a condenser to selective reject heat to or absorb heat from the source; and 
 a third heat exchanger fluidly connected to the space, the third exchanger being operable alternately as an evaporator and a condenser to selectively cool or heat the space. 
 
     
     
         11 . The method of  claim 10  wherein the refrigerant circuit further comprises:
 a first one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the second heat exchanger and only when the second heat exchanger is operating as an evaporator; and 
 a second one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the third heat exchanger and only when the third heat exchanger is operating as an evaporator. 
 
     
     
         12 . The method of  claim 11  wherein each of the first and second expansion valves comprises an electronic expansion valve operable between a metering position in which refrigerant is metered into the heat exchanger and a closed position in which flow through the expansion valve is blocked, and wherein the valve assembly includes a check valve for each electronic expansion valve configured to allow fluid to bypass the expansion valve. 
     
     
         13 . The method of  claim 11  wherein each of the first and second expansion valves comprises a mechanical expansion valve and a solenoid shut-off valve, and wherein the valve assembly includes a check valve for each expansion valve configured to allow fluid to bypass the expansion valve. 
     
     
         14 . The method of  claim 8  wherein the refrigerant circuit further comprises a valve assembly in the conduit assembly, and wherein valve assembly comprises a diverting valve and a reversing valve. 
     
     
         15 . The method of  claim 8  further wherein in any of the four modes of operation one of the plurality of heat exchangers is inactive and wherein the method further comprises reclaiming charge from the inactive heater exchanger to the suction side of the compressor.