Heat pump apparatus and hot water supply system

Abstract

A heat pump apparatus according to the present disclosure is a heat pump apparatus for supplying heat for hot water storage operation to raise a temperature of water in a hot water storage tank. The heat pump apparatus includes a constant speed compressor, a first heat exchanger for exchanging heat between refrigerant compressed by the constant speed compressor and a heat medium, a variable speed compressor, and a second heat exchanger for exchanging heat between refrigerant compressed by the variable speed compressor and the heat medium downstream of the first heat exchanger. A hot water supply system according to the present disclosure includes the heat pump apparatus, the hot water storage tank, and a water heat exchanger for exchanging heat between the heat medium flowed out of the heat pump apparatus and water stored in the hot water storage tank.

1 . A heat pump apparatus for supplying heat for hot water storage operation to raise a temperature of water in a hot water storage tank, the heat pump apparatus comprising:
 a constant speed compressor;   a first heat exchanger for exchanging heat between refrigerant compressed by the constant speed compressor and a heat medium;   a variable speed compressor; and   a second heat exchanger for exchanging heat between refrigerant compressed by the variable speed compressor and the heat medium downstream of the first heat exchanger.   
     
     
         2 . The heat pump apparatus according to  claim 1 , further comprising processing circuitry capable of receiving information about a stored hot water temperature which is the temperature of water in the hot water storage tank, wherein
 the processing circuitry is configured to actuate both the variable speed compressor and the constant speed compressor to start the hot water storage operation in a case where the stored hot water temperature before the hot water storage operation is started is lower than a reference, and actuate the variable speed compressor to start the hot water storage operation without actuating the constant speed compressor in a case where the stored hot water temperature before the hot water storage operation is started is more than or equal to the reference.   
     
     
         3 . The heat pump apparatus according to  claim 1 , further comprising:
 a heat pump outlet temperature sensor for sensing a heat pump outlet temperature which is a temperature of the heat medium flowing out of the heat pump apparatus; and   processing circuitry configured to adjust a rotation speed of the variable speed compressor such that the heat pump outlet temperature does not exceed an upper limit value while the hot water storage operation is executed.   
     
     
         4 . The heat pump apparatus according to  claim 1 , further comprising:
 a heat pump inlet temperature obtainer configured to sense or estimate a heat pump inlet temperature which is a temperature of the heat medium flowing into the heat pump apparatus; and   processing circuitry configured to stop the constant speed compressor and continue actuating the variable speed compressor when the heat pump inlet temperature reaches a reference while the hot water storage operation in which both the variable speed compressor and the constant speed compressor are actuated is executed.   
     
     
         5 . The heat pump apparatus according to  claim 4 , wherein the heat pump inlet temperature obtainer is configured to estimate the heat pump inlet temperature using information about a stored hot water temperature which is the temperature of water in the hot water storage tank. 
     
     
         6 . The heat pump apparatus according to  claim 1 , further comprising processing circuitry configured to stop the constant speed compressor and continue actuating the variable speed compressor when a rotation speed of the variable speed compressor decreases to a lower limit value while the hot water storage operation in which both the variable speed compressor and the constant speed compressor are actuated is executed. 
     
     
         7 . The heat pump apparatus according to  claim 1 , further comprising processing circuitry configured to increase a rotation speed of the variable speed compressor when stopping the constant speed compressor while the hot water storage operation in which both the variable speed compressor and the constant speed compressor are actuated is executed. 
     
     
         8 . The heat pump apparatus according to  claim 1 , wherein the refrigerant is a combustible refrigerant. 
     
     
         9 . A hot water supply system comprising:
 the heat pump apparatus according to  claim 1 ;   the hot water storage tank; and   a water heat exchanger for exchanging heat between the heat medium flowed out of the heat pump apparatus and water stored in the hot water storage tank.   
     
     
         10 . The hot water supply system according to  claim 9 , comprising:
 an outlet provided for the hot water storage tank;   a tank outgoing tube for connecting the outlet to a water inlet of the water heat exchanger provided outside the hot water storage tank;   an inlet provided for the hot water storage tank at a position above the outlet;   a tank return tube for connecting a water outlet of the water heat exchanger to the inlet;   a stored hot water temperature sensor installed in the hot water storage tank at a position of a height between the outlet and the inlet; and   processing circuitry configured to estimate a heat pump inlet temperature which is a temperature of the heat medium flowing into the heat pump apparatus using a result sensed by the stored hot water temperature sensor.   
     
     
         11 . A hot water supply system comprising:
 the heat pump apparatus according to  claim 1 ;   the hot water storage tank;   an outgoing water path for causing water flowed out of the hot water storage tank to flow into the first heat exchanger of the heat pump apparatus as the heat medium; and   a return water path for causing the water which is the heat medium flowed out of the second heat exchanger of the heat pump apparatus to flow into the hot water storage tank.