Storage type heat pump hot water supplying apparatus

Abstract

A storage type heat pump hot water supplying apparatus includes: control circuitry to control a compressor frequency and a pump rotational speed, the compressor frequency being an operating frequency of the compressor, the pump rotational speed being a rotational speed of a water pump. The control circuitry is configured to control, in a heat accumulating operation for accumulating hot water in the hot water storage tank, the pump rotational speed so that the actual hot water discharge temperature becomes equal to a target hot water discharge temperature. The heat accumulating operation includes a first operation and a second operation after the first operation. The compressor frequency in the first operation is higher than the compressor frequency in the second operation. The target hot water discharge temperature in the first operation is lower than the target hot water discharge temperature in the second operation.

1 . A storage type heat pump hot water supplying apparatus, comprising:
 a heat source machine including a compressor to compress refrigerant and a water heat exchanger to exchange heat between water and the refrigerant compressed by the compressor;   a hot water storage tank to store hot water heated by the heat source machine;   a water circuit including a feed path connecting a lower part of the hot water storage tank to a water inlet of the water heat exchanger, a return path connecting a water outlet of the water heat exchanger to an upper part of the hot water storage tank, and a water pump provided in the feed path or the return path;   a temperature sensor to detect an actual hot water discharge temperature, the actual hot water discharge temperature being a temperature of hot water flowing out of the water heat exchanger; and   control circuitry to control a compressor frequency and a pump rotational speed, the compressor frequency being an operating frequency of the compressor, the pump rotational speed being a rotational speed of the water pump,   wherein the control circuitry is configured to control, in a heat accumulating operation for accumulating hot water in the hot water storage tank, the pump rotational speed so that the actual hot water discharge temperature becomes equal to a target hot water discharge temperature,   wherein the heat accumulating operation includes a first operation and a second operation after the first operation,   wherein the compressor frequency in the first operation is higher than the compressor frequency in the second operation, and   wherein the target hot water discharge temperature in the first operation is lower than the target hot water discharge temperature in the second operation.   
     
     
         2 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the pump rotational speed in the first operation is higher than the pump rotational speed in the second operation. 
     
     
         3 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the target hot water discharge temperature is kept constant within a period from a start of the first operation to an end of the first operation. 
     
     
         4 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the target hot water discharge temperature is increased in a stepwise manner within a period from a start of the first operation to an end of the first operation. 
     
     
         5 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the target hot water discharge temperature is continuously increased within a period from a start of the first operation to an end of the first operation. 
     
     
         6 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the compressor frequency is kept constant within the period from the start of the first operation to the end of the first operation. 
     
     
         7 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the compressor frequency is reduced in a stepwise manner within the period from the start of the first operation to the end of the first operation. 
     
     
         8 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the compressor frequency is continuously reduced within the period from the start of the first operation to the end of the first operation. 
     
     
         9 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the heat source machine further includes an air heat exchanger to exchange heat between outdoor air and the refrigerant, and a blower to send air to the air heat exchanger,
 wherein the control circuitry sets a rotational speed of the blower in the first operation to be higher than a rotational speed of the blower in the second operation.   
     
     
         10 . The storage type heat pump hot water supplying apparatus according to  claim 1 , wherein the heat accumulating operation including the first operation and the second operation is a daytime heat accumulating operation performed in daytime hours being hours including daytime of a day, and
 in a nighttime heat accumulating operation performed in nighttime hours being hours other than the daytime hours of the day, the control circuitry executes the second operation by omitting the first operation.