JP6682002B2 - Hot water storage type water heater, hot water supply method and program - Google Patents

Description

  The present invention relates to a hot water storage type hot water supply device, a hot water supply method, and a program.

  A hot water storage type hot water supply device is known in which hot water generated by heating water is stored in a hot water storage tank, and hot water is supplied from the hot water storage tank (for example, see Patent Document 1). Patent Document 1 describes a system in which water in a hot water storage tank is boiled and supplied by a heat pump. When the amount of heat stored in the hot water storage tank is insufficient, this system heats the water taken out from the hot water storage tank with a burner to supply hot water without re-boiling the water in the hot water storage tank over time.

JP, 2014-214958, A

  In the system described in Patent Document 1, a boiling operation in which the temperature of the hot water in the hot water storage tank is 60 ° C. is performed in order to suppress the growth of various bacteria in the hot water storage tank. Even if hot water of about 30 to 40 ° C., which is relatively high, is stored in the hot water storage tank, if the water in the hot water storage tank stays without boiling operation within a certain time, promptly It is necessary to start the boiling operation to raise the hot water temperature in the hot water storage tank to 60 ° C or higher. However, such an operation of boiling hot water at a relatively high temperature has lower energy consumption efficiency than an operation of boiling low temperature water. Therefore, there is room for improving the energy consumption efficiency of the hot water storage type water heater.

  The present invention has been made in view of the above circumstances, and an object thereof is to improve the energy consumption efficiency of a hot water storage water heater.

To achieve the above object, a hot water storage type hot water supply apparatus of the present invention includes a first heating means for generating the first hot water of the first temperature by heating water, and hot water storage tank for storing water and a first water A heat exchanger for preheating the city water by heat exchange between the first hot water taken from the hot water storage tank and the city water, and a second heat for heating the city water preheated by the heat exchanger and second heating means, when the amount of the first hot water supplied to the hot water outlet from the hot water storage tank within a predetermined time is less than the capacity of the hot water storage tank, and a control means for supplying a second hot water hot water port, The first heating means includes the water stored in the hot water storage tank and the first hot water when the amount of the first hot water supplied from the hot water storage tank to the hot water supply port is smaller than the capacity within a preset time. When the average temperature with the hot water becomes lower than the threshold value, the water taken from the hot water storage tank is heated to the first temperature. When the temperature of the water flowing into the first heating means exceeds the upper limit value, the control means stops the heating by the first heating means and operates the pump. The hot water in the lower part of the hot water storage tank is circulated to the upper part .

  According to the present invention, when the amount of the first hot water supplied from the hot water storage tank to the hot water supply port within the preset time is smaller than the capacity of the hot water storage tank, heat exchange with the first hot water taken from the hot water storage tank is performed. The city water preheated by is heated and supplied to the hot water supply port. Therefore, it is possible to lower the water temperature in the hot water storage tank while supplying the hot water by utilizing the heat quantity of the relatively high temperature hot water in the hot water storage tank. Thereby, the energy consumption efficiency of the hot water storage type water heater can be improved.

The figure which shows the structure of the hot water storage type water heater which concerns on Embodiment 1. Flow chart showing the control processing of the hot water supply switching valve Flow chart showing the operation process in the tank hot water supply mode Flow chart showing the operation process in the preheating hot water supply mode Diagram showing temperature change of water passing through heat exchanger The figure which shows the relationship between the primary side flow volume of a heat exchanger, and a secondary side flow volume. Flow chart showing heat treatment Flow chart showing the filling operation process Diagram for explaining actuator control Diagram for explaining control of the discharge switching valve Flow chart showing high temperature boiling operation processing The figure which shows the relationship between the incoming water temperature of a 1st heating unit, and COP. Diagram showing changes in hot water supply load, hot water storage tank heat storage capacity, and heating capacity The figure which shows the structure of the hot water storage type water heater which concerns on Embodiment 2.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1.
FIG. 1 shows the configuration of a hot water storage water heater 1000 according to the first embodiment. The hot water storage type water heater 1000 is a water heater that heats the water obtained from the water inlet 101 and supplies hot water from the hot water inlet 102. The water supply port 101 is a water supply end connected to the water supply system, and receives supply of city water as water supply from the water supply system. City water is tap water or tap water, for example. The hot water supply port 102 is a hot water supply end connected to a hot water utilization point represented by a hot water supply tap such as a faucet and a shower. In addition, the thick solid line in FIG. 1 shows a water distribution pipe, and the broken line shows a signal line.

  As shown in FIG. 1, the hot water storage type water heater 1000 includes a hot water storage unit 100 that stores hot water in a hot water storage tank 120, a first heating unit 210 that heats stored water in the hot water storage tank 120, and a hot water storage tank 120. Instead, it has a second heating unit 220 for heating and supplying hot water, and a terminal 40 for the user to set the hot water temperature.

(Configuration of hot water storage unit 100)
The hot water storage unit 100 includes a hot water storage tank 120 for storing water supplied through the water supply pipe 110 and hot water generated from the water, a circulation pump 130 for circulating the water stored in the hot water storage tank 120, and hot water of the hot water storage tank 120. A mixing valve 140 that mixes city water, a heat exchanger 160 that preheats city water by using the heat stored in the hot water storage tank 120, a hot water supply switching valve 180 that switches a flow path communicating with a hot water supply pipe 190, and a hot water storage unit 100 And a control unit 11 for controlling the constituent elements of.

  The water supply pipe 110 is connected to the water supply port 101 and the lower part of the hot water storage tank 120. A temperature sensor 111 for measuring the temperature of city water and a pressure reducing valve 112 for setting the pressure of the hot water storage tank 120 are attached to the water supply pipe 110. The temperature sensor 111 transmits a signal indicating the measurement result to the control unit 11. Further, the water supply pipe 110 is branched between the water supply port 101 and the pressure reducing valve 112 and is connected to the secondary side inlet of the heat exchanger 160. Further, the water supply pipe 110 is branched between the pressure reducing valve 112 and the hot water storage tank 120, and is connected to the suction port of the mixing valve 140. The water supply pipe 110 introduces city water from the water supply port 101 to the hot water storage tank 120, the heat exchanger 160, and the mixing valve 140.

  The hot water storage tank 120 has a capacity of 150 to 600 L and is, for example, a 300 L or 500 L tank. Water is normally stored in the hot water storage tank 120 until it is full. City water is supplied to the lower portion of the hot water storage tank 120 to form a low temperature layer, and hot water generated by the first heating unit 210 is supplied to the upper portion of the hot water storage tank 120 to form a high temperature layer. Due to the temperature gradient of these layers, thermal stratification is formed inside the hot water storage tank 120. On the surface of the hot water storage tank 120, a plurality of temperature sensors 121, 122, 123, 124 for measuring the temperature of hot water are attached in the height direction. These temperature sensors 121 to 124 send signals indicating the measurement results to the control unit 11.

  The suction port of the circulation pump 130 is connected to the lower part of the hot water storage tank 120 and the primary side outlet of the heat exchanger 160 via a suction switching valve 131. The suction switching valve 131 switches the flow path so that either the hot water storage tank 120 or the heat exchanger 160 and the circulation pump 130 are communicated with each other in accordance with a control command from the control unit 11. The discharge port of the circulation pump 130 is connected to the lower portion of the hot water storage tank 120 and the first heating unit 210 via the discharge switching valve 132. The discharge switching valve 132 switches the flow path so that either the hot water storage tank 120 or the first heating unit 210 and the circulation pump 130 communicate with each other in accordance with a control command from the control unit 11.

  The circulation pump 130 operates at a rotation speed according to a control command from the control unit 11 and sends out water, thereby generating a water flow flowing in a circulation path described later.

  The inlet of the mixing valve 140 is connected to the water supply pipe 110 and the upper part of the hot water storage tank 120, and the outlet of the mixing valve 140 is connected to the inlet of the hot water switching valve 180. Mixing valve 140 discharges hot water generated by mixing the hot water flowing out from the upper part of hot water storage tank 120 and city water to hot water supply switching valve 180. The mixing ratio of the mixing valve 140 is variable and follows the control command from the control unit 11. Further, a temperature sensor 141 that measures the temperature of the hot water taken out from the hot water storage tank 120 is attached to the water distribution pipe that connects the mixing valve 140 and the hot water storage tank 120. The temperature sensor 141 transmits a signal indicating the measurement result to the control unit 11.

  The heat exchanger 160 preheats the city water by exchanging heat between the hot water of the hot water storage tank 120 flowing to the primary side and the city water flowing to the secondary side. The primary side inlet of the heat exchanger 160 is connected to the upper part of the hot water storage tank 120, and the primary side outlet is connected to the suction port of the suction switching valve 131. A temperature sensor 161 for measuring the temperature of water flowing out from the primary side outlet is attached to the water distribution pipe connecting the primary side outlet and the intake switching valve 131. Further, the secondary inlet of the heat exchanger 160 is connected to the water supply pipe 110, and the water supply pipe 110 near the secondary inlet is provided with a flow rate sensor 163 for measuring the amount of water flowing into the secondary inlet. ing. Further, the secondary outlet of the heat exchanger 160 is connected to the second heating unit 220, and the water pipe near the secondary outlet has a temperature sensor 162 for measuring the temperature of the water flowing out from the secondary outlet. Is attached. The temperature sensors 161, 162 and the flow rate sensor 163 send a signal indicating the measurement result to the control unit 11.

  The intake port of the hot water supply switching valve 180 is connected to the discharge port of the mixing valve 140 and the second heating unit 220, and the discharge port of the hot water supply switching valve 180 is connected to the hot water supply pipe 190. The hot water supply switching valve 180 switches the supply source of the hot water introduced into the hot water supply pipe 190 to one of the hot water storage tank 120 and the second heating unit 220 in accordance with a control command from the control unit 11. A water pressure reducing valve 170 for setting the hot water supply pressure is attached to the water distribution pipe that guides the hot water from the second heating unit 220 to the hot water supply switching valve 180.

  The hot water supply pipe 190 is connected to the discharge port of the hot water supply switching valve 180 and the hot water supply port 102, and guides the hot water discharged from the hot water supply switching valve 180 to the hot water supply port 102. A temperature sensor 191 for measuring the temperature of the hot water supply and a flow rate sensor 192 for measuring the amount of hot water are attached to the hot water supply pipe 190. The temperature sensor 191 and the flow sensor 192 send a signal indicating the measurement result to the control unit 11.

  The control unit 11 includes a microprocessor that executes a program, a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read-Only Memory) that stores the program. The control unit 11 acquires the measurement results of the temperature sensors 111, 121 to 124, 141, 161, 162, 191 and the flow rate sensors 163, 192. Further, control unit 11 acquires information including hot water supply temperature from terminal 40. Then, the control unit 11 controls the rotation speed of the circulation pump 130, the flow path communicated with the intake switching valve 131, the discharge switching valve 132, and the hot water switching valve 180, and the mixing ratio of the mixing valve 140. Details of the control processing by the control unit 11 will be described later.

(Structure of the first heating unit 210)
The first heating unit 210 is a main heat source for generating hot water by heating the stored water in the hot water storage tank 120 with a heat pump. The first heating unit 210 is connected to the hot water storage unit 100 via a water inlet pipe for introducing water from the lower portion of the hot water storage tank 120 and a hot water outlet pipe for supplying the generated hot water to the upper portion of the hot water storage tank 120. The first heating unit 210 controls the refrigerant circulation path in which the compressor 211, the heat exchanger 212, the expansion valve 213, and the evaporator 214 are connected in this order by refrigerant pipes, and controls the components of the first heating unit 210. And a portion 21. As the refrigerant to be circulated in the refrigerant circulation path, for example, CO2, HFC, HC, and HFO can be used, but the refrigerant is not limited to this, and the kind of the refrigerant is arbitrary.

  The compressor 211 compresses the refrigerant and discharges it to the heat exchanger 212 as a high-temperature and high-pressure gas. The compressor 211 according to the present embodiment has an inverter and sets the rotation speed according to a control command from the control unit 21.

  The heat exchanger 212 heats the water on the secondary side to generate hot water by exchanging heat between the high temperature refrigerant on the primary side and the water on the secondary side. The secondary inlet of the heat exchanger 212 is connected to the discharge outlet of the discharge switching valve 132 via a water inlet pipe. The secondary outlet of the heat exchanger 212 is connected to the upper part of the hot water storage tank 120 via a hot water outlet pipe. The refrigerant flowing into the heat exchanger 212 becomes a low-temperature high-pressure liquid by being cooled, and is discharged to the expansion valve 213.

  The expansion valve 213 decompresses the refrigerant and discharges it as a low-temperature low-pressure liquid to the evaporator 214. The expansion valve 213 according to the present embodiment can adjust the opening degree, and according to an instruction from the control unit 21, adjusts the opening degree so that the suction temperature or the discharge temperature of the compressor 211 becomes a constant temperature.

  The evaporator 214 is a heat exchanger that exchanges heat between the outside air guided by a blower (not shown) and the refrigerant. The refrigerant flowing into the evaporator 214 becomes high-temperature and low-pressure gas by heat exchange with the outside air and is discharged to the suction port of the compressor 211.

  The control unit 21 includes a microprocessor that executes a program, a RAM, and an EEPROM that stores the program. The control unit 21 acquires information from the terminal 40. This information includes commands for starting and ending the heating operation by the first heating unit 210. Then, the control unit 21 adjusts the heating capacity of the first heating unit 210 by controlling the rotation speed of the compressor 211 and the opening degree of the expansion valve 213. This heating capacity may be kept constant by the control unit 21, or may be changed by the control unit 21 cooperating with the terminal 40 and the control unit 11.

(Structure of the second heating unit 220)
The second heating unit 220 is an auxiliary heat source that heats city water by burning fuel represented by gas and kerosene with a burner to generate hot water. The second heating unit 220 is connected to the hot water storage unit 100 via an inlet pipe for introducing the city water preheated by the heat exchanger 160 and an outlet pipe for supplying the generated hot water to the hot water supply switching valve 180. . In addition, the second heating unit 220 is connected to the bath 50 through a forward pipe that supplies hot water to the bath 50 and a return pipe that guides water from the bath 50.

  The second heating unit 220 includes a heat exchanger 221, which heats city water, a heat exchanger 222 and a pump 223, which supply hot water to the bathtub, and a controller 22 which controls the components of the second heating unit 220. ,have.

  The heat exchanger 221 heats the city water to generate hot water by exchanging heat between the exhaust gas generated by the combustion by the burner and the city water. A flow sensor 224 that measures the amount of city water flowing from the hot water storage unit 100 is attached to the water inlet pipe connected to the heat exchanger 221 and the hot water storage unit 100. The flow rate sensor 224 transmits a signal indicating the measurement result to the control unit 22. Further, a control valve 225 having a variable opening degree for controlling the amount of water is attached to the water inlet pipe between the flow rate sensor 224 and the heat exchanger 221. The control valve 225 adjusts the water flow rate according to a control command from the control unit 22.

  Further, the water supply pipe is connected to a bypass path that branches between the control valve 225 and the heat exchanger 221 and bypasses the heat exchanger 221. A bypass valve 226 having a variable opening degree, which is connected in parallel with the heat exchanger 221, is provided in the bypass passage. The bypass valve 226 sets the opening according to a control command from the control unit 22.

  Further, the hot water outlet pipe connected to the heat exchanger 221 and the hot water storage unit 100 joins with a bypass passage provided with a bypass valve 226. The hot water discharge pipe sends hot water discharged from the heat exchanger 221 and city water that has passed through the bypass passage to the hot water storage unit 100. A temperature sensor 228 for measuring the temperature of the mixed hot and cold water is attached to the tap water pipe. The temperature sensor 228 transmits a signal indicating the measurement result to the control unit 22. Further, the hot water supply pipe branches off downstream from the confluence portion with the bypass passage and is connected to the middle of the return pipe of the bathtub 50 via the hot water filling valve 227 with a variable opening degree. The filling valve 227 sets the opening degree according to a control command from the control unit 22.

  The heat exchanger 222 heats the water to generate hot water by exchanging heat between the exhaust gas generated by the combustion by the burner and the water. The return pipe connected to the heat exchanger 222 and the bath 50 is branched in the middle to be connected to the hot water pipe, and a pump 223 is attached between the connection part with the hot water pipe and the heat exchanger 222. There is. The pump 223 operates at a rotation speed according to a control command from the control unit 22, and sends the water discharged from the water filling valve 227 or the water taken out from the bath 50 to the heat exchanger 222. The hot water generated by the heat exchanger 222 is supplied to the bathtub 50 through the return pipe.

  The control unit 22 includes a microprocessor that executes a program, a RAM, and an EEPROM that stores the program. The control unit 22 acquires the measurement result from the flow rate sensor 224 and acquires the information from the terminal 40. This information includes the hot water supply temperature input to the terminal 40, the start command of the filling operation, and the start command of the reheating operation. Then, the control unit 22 instructs the burner to start and end combustion, and controls the opening degrees of the control valve 225, the bypass valve 226, and the water filling valve 227, and the rotation speed of the pump 223. Details of the control processing by the control unit 22 will be described later.

  Next, various operations executed by the hot water storage type water heater 1000 will be described. These operations are realized by the control units 11, 21, 22 and the terminal 40 cooperating by communication via a signal line.

(Hot water storage operation)
The hot water storage operation is a boiling operation in which the first heating unit 210 heats the stored water in the hot water storage tank 120 to generate hot water. The hot water storage operation starts according to the amount of heat stored in the hot water storage tank 120.

  Regarding the heat storage amount of the hot water storage tank 120, the control unit 11 calculates the heat storage amount effective for the hot water supply load among the heat storage amounts of the hot water in the hot water storage tank 120 based on the measurement results of the temperature sensors 121 to 124. Obtainable. For example, when a relatively small amount of general hot water supply load occurs, the thermal energy of the hot water in the hot water storage tank 120 is used by mixing the hot water and city water. Therefore, the heat storage amount is calculated by integrating the difference between the measurement results of the temperature sensors 121 to 124 and the reference value with respect to the volume of the hot water storage tank 120, using the reference value of the thermal energy as the temperature of the city water. The reference value may be a predetermined value. Further, for example, when the hot water supply temperature set by the user is 40 ° C., the hot water of 38 ° C. stored in the hot water storage tank 120 cannot be used, so that the temperature of the hot water stored in the hot water storage tank 120 is equal to or higher than a specific temperature. The heat storage amount may be calculated by integrating only the hot water. The specific temperature may be a predetermined value such as 45 ° C., or may be a value determined according to the hot water supply temperature. The hot water supply load means the demand for hot water supply, and the general hot water supply load may be a hot water supply load other than the hot water supply load due to the hot water filling operation and the reheating operation.

  The control unit 11 monitors the heat storage amount of the hot water storage tank 120 calculated from the measurement results of the temperature sensors 121 to 124, and starts the hot water storage operation when the heat storage amount falls below a preset specific threshold value. Specifically, the control unit 11 causes the first heating unit 210 to generate hot water in cooperation with the terminal 40 and the control unit 21. The threshold value for starting the hot water storage operation corresponds to, for example, 10% of the maximum heat storage amount of the hot water storage tank 120.

  In the hot water storage operation, the terminal 40 determines the target temperature of hot water to be generated according to the hot water supply temperature set by the user. Here, heat is radiated from the surface of the hot water storage tank 120 between the time when the hot water is boiled in the first heating unit 210 and the time when the hot water is actually supplied from the hot water supply port 102, and the mixing ratio of city water is mixed by the mixing valve 140. May not be set to zero. Therefore, terminal 40 according to the present embodiment obtains the target temperature by adding a fixed value to the set hot water supply temperature. For example, when the hot water supply temperature is set to 40 ° C., a positive value is set to A and (40 + A) ° C. is calculated as the target temperature. Then, the terminal 40 transmits the target temperature to the control unit 11.

  When the hot water storage operation is started, the control unit 11 controls the suction switching valve 131 so that the lower portion of the hot water storage tank 120 and the suction port of the circulation pump 130 communicate with each other, and the discharge port of the circulation pump 130 and the first heating unit 210 are connected to each other. The discharge switching valve 132 is controlled so as to communicate with each other. As a result, as shown by the solid line arrow in FIG. 1, from the lower part of the hot water storage tank 120 to the upper part of the hot water storage tank 120 via the suction switching valve 131, the circulation pump 130, the discharge switching valve 132, and the heat exchanger 212. A circulation path is formed back to.

  Then, the control unit 11 operates the circulation pump 130 to send the low-temperature water existing under the hot water storage tank 120 to the heat exchanger 212. Thereby, the hot water generated by the first heating unit 210 is supplied to the upper part of the hot water storage tank 120. The control unit 11 adjusts the rotation speed of the circulation pump 130 so that hot water having a target temperature is generated when the circulation pump 130 is operated.

  Then, when the heat storage amount of hot water storage tank 120 reaches the target hot water storage amount, control unit 11 stops the hot water storage operation. The target hot water storage amount is calculated, for example, from the difference between the hot water supply load predicted to occur from the present time to a specific time in the future and the current heat storage amount of the hot water storage tank 120. The future hot water supply load is preferably estimated by learning from the actual hot water supply load in the past several days. The actually generated hot water supply load is an integrated value of the hot water supply amounts measured by the flow rate sensor 192, and an integrated value of the difference between the hot water supply temperature measured by the temperature sensor 191 and the temperature of city water measured by the temperature sensor 111. Calculated from

  It should be noted that control unit 11 may execute the hot water storage operation during a specific time period regardless of the amount of heat stored in hot water storage tank 120. The specific time period is, for example, a time period when the electricity rate at midnight is low, or a time period when surplus of the generated electric power generated by the power generator installed together with the hot water storage water heater 1000 occurs.

(Control processing of hot water supply switching valve 180)
Next, the control process of the hot water supply switching valve 180 by the control unit 11 will be described with reference to FIG. The control process shown in FIG. 2 is repeatedly executed at regular intervals. The fixed period is, for example, 1 minute.

  First, the control unit 11 determines whether or not the heat storage amount of the hot water storage tank 120 exceeds a preset threshold value (step S1).

  This threshold value corresponds to, for example, the maximum load as one hot water supply load among the hot water supply loads that have occurred in the past several days of the general hot water supply load. In addition, the control unit 11 determines that the heat storage amount exceeds the threshold value when the measurement result by any of the temperature sensors 121 to 124 is higher than (hot water supply temperature + B) ° C., where B is a constant positive value. Good. Further, among the general hot water supply loads, a load having a relatively large value, as represented by a single shower load, may be adopted as the threshold value. The shower load for one time is, for example, 50 L at 40 ° C. conversion. Furthermore, the control unit 11 may use a threshold value set by the user for the terminal 40. The threshold value for controlling the hot water supply switching valve 180 is generally larger than the threshold value for starting the hot water storage operation, and corresponds to, for example, 30% of the maximum heat storage amount of the hot water storage tank 120.

  When it is determined that the heat storage amount exceeds the threshold value (step S1; Yes), the control unit 11 controls the hot water supply switching valve 180 so that the hot water supply port 102 and the discharge port of the mixing valve 140 communicate with each other to set the operation mode. The tank hot water supply mode is set (step S2). The tank hot water supply mode is an operation mode in which hot water in the hot water storage tank 120 is supplied from the hot water supply port 102. Details of the tank hot water supply mode will be described later.

  On the other hand, when it is determined that the heat storage amount does not exceed the threshold value (step S1; No), the control unit 11 controls the hot water supply switching valve 180 so that the hot water supply port 102 and the discharge port of the pressure reducing valve 170 communicate with each other, The operation mode is set to the preheating hot water supply mode (step S3). The preheating hot water supply mode is an operation mode in which hot water generated by the second heating unit 220 from city water preheated by the heat exchanger 160 is supplied from the hot water supply port 102. Details of the preheating hot water supply mode will be described later.

  Then, control unit 11 ends the control process for hot water supply switching valve 180.

(Tank hot water supply mode operation processing)
Next, the operation process of the tank hot water supply mode executed by the control unit 11 will be described with reference to FIG. The process shown in FIG. 3 starts when the operation mode is set to the tank hot water supply mode.

  First, the control unit 11 determines whether the hot water supply flow rate exceeds a threshold value (step S11). Specifically, when the hot water tap connected to hot water inlet 102 is opened, the amount of hot water measured by flow rate sensor 192 becomes greater than zero. The control unit 11 determines whether or not the value measured by the flow rate sensor 192 is equal to or higher than a certain threshold value that can be stably detected.

  When it is determined that the hot water supply flow rate does not exceed the threshold value (step S11; No), the control unit 11 repeats the determination of step S11. On the other hand, when it is determined that the hot water supply flow rate exceeds the threshold value (step S11; Yes), the controller 11 controls the mixing valve 140 to adjust the hot water supply temperature (step S12). Specifically, control unit 11 controls the mixing ratio of mixing valve 140 such that the hot water supply temperature measured by temperature sensor 191 is equal to the hot water supply temperature set in terminal 40. Here, when hot water flows from the upper part of the hot water storage tank 120 to the mixing valve 140, low temperature city water flows into the lower part of the hot water storage tank 120 through the pressure reducing valve 112.

  Next, control unit 11 determines whether or not the hot water supply flow rate is smaller than the threshold value (step S13). This threshold is equal to the threshold used in step S11.

  When it is determined that the hot water supply flow rate is smaller than the threshold value (step S13; Yes), the control unit 11 enters a standby state and repeats the processing from step S11. On the other hand, when it is determined that the hot water supply flow rate is not smaller than the threshold value (step S13; No), the control unit 11 repeats the processing from step S12.

  When the operation processing in the tank hot water supply mode is being executed, hot water supply switching valve 180 connects mixing valve 140 and hot water supply opening 102 to form a flow path connecting second heating unit 220 and hot water supply opening 102. Cut off. Therefore, the city water does not flow into the second heating unit 220, and the city water is not heated by the second heating unit 220.

(Preheated hot water supply mode operation processing)
Next, the operation process of the preheating hot water supply mode executed by the control unit 11 will be described with reference to FIG. This operation process is a process of preheating the city water by the heat exchanger 160. The process shown in FIG. 4 starts when the operation mode is set to the preheating hot water supply mode.

  First, the control unit 11 switches the flow path communicating with the suction switching valve 131 to the heat exchanger 160 side (step S21). Next, the control unit 11 switches the flow path communicating with the discharge switching valve 132 to the hot water storage tank 120 side (step S22). As a result, as shown by the broken line arrow in FIG. 1, the hot water storage tank 120 is passed from the upper portion of the hot water storage tank 120 via the heat exchanger 160, the suction switching valve 131, the circulation pump 130, and the discharge switching valve 132. A circulation path that returns to the bottom is formed.

  Next, the control unit 11 determines whether or not the preheating flow rate measured by the flow rate sensor 163 exceeds the threshold value (step S23). This preheat flow rate is the amount of water flowing into the second heating unit 220 through the secondary side of the heat exchanger 160, and increases when the hot water tap is opened. The threshold value for determining the preheating flow rate corresponds to a certain amount of water that the flow rate sensor 163 can stably detect.

  When it is determined that the preheating flow rate does not exceed the threshold value (step S23; No), the control unit 11 repeats the determination of step S23. On the other hand, when it is determined that the preheating flow rate exceeds the threshold value (step S23; Yes), the control unit 11 controls the circulation pump 130 to generate the water flow in the circulation path and adjust the preheating temperature (step S24). When the water flow is generated in the circulation path, the hot water flowing out from the upper portion of the hot water storage tank 120 is cooled by passing through the primary side of the heat exchanger 160, and returns to the lower portion of the hot water storage tank 120. In addition, the control unit 11 sets the difference between the temperature of the city water measured by the temperature sensor 111 and the temperature of the primary outlet measured by the temperature sensor 161 to be equal to a preset target value. The preheating temperature is adjusted by controlling the rotation speed of the circulation pump 130.

  The adjustment of the preheating temperature will be described with reference to FIG. FIG. 5 shows the temperature change of the water flowing through the heat exchanger 160. In FIG. 5, the line L1 shows the temperature change of the water flowing through the primary side flow path, and when the water flows from the primary side inlet to the primary side outlet, the water temperature changes along the solid line arrow. Tw1i corresponds to the temperature of water flowing into the primary side inlet, and Tw1o corresponds to the temperature of water flowing out from the primary side outlet. The line L2 indicates the temperature change of the water flowing through the secondary side flow path, and when the water flows from the secondary side inlet to the secondary side outlet, the water temperature changes along the broken line arrow. Tw2i corresponds to the temperature of water flowing into the secondary side inlet, and Tw2o corresponds to the temperature of water flowing out from the secondary side outlet.

  Here, the control unit 11 controls the rotation speed of the circulation pump 130 so that ΔTwL, which is the difference between Tw1o and Tw2i shown in FIG. 5, becomes equal to the target value.

  For example, when the flow rate on the secondary side is small and the flow rate on the primary side is excessive, Tw1o becomes high, and the temperature of the water flowing into the lower portion of the hot water storage tank 120 becomes high. Since it is desirable that the temperature of the water flowing into the lower part of the hot water storage tank 120 is low to some extent, the control unit 11 reduces the rotation speed of the circulation pump 130 in this case to bring ΔTwL close to the target value. On the other hand, when the flow rate on the secondary side is large and the flow rate on the primary side is too small, Tw1o becomes low, and the city water cannot be sufficiently preheated. In this case, the control unit 11 increases the rotation speed of the circulation pump 130 to bring ΔTwL close to the target value.

  That is, when the rotation speed of the circulation pump 130 is controlled according to ΔTwL, the flow rate on the primary side can be set to an appropriate flow rate in consideration of the amount of preheat and the efficiency of heat exchange according to the flow rate on the secondary side. . By properly adjusting ΔTwL, it is possible to lower the water temperature in the lower portion of the hot water storage tank 120 and lower the water inlet temperature of the first heating unit 210 when the boiling operation is subsequently performed. As a result, the energy consumption efficiency of the boiling operation can be improved. In particular, when the refrigerant flowing in the refrigerant circuit of the first heating unit 210 is CO2, the energy consumption efficiency can be significantly improved by lowering the incoming water temperature. Furthermore, since the heat exchanger 160 gives the city water an appropriate amount of heat according to the flow rate on the secondary side, the heat stored in the hot water storage tank 120 can be effectively used.

  The control of the rotation speed of the circulation pump 130 is performed by instructing the circulation pump 130 of the rotation speed according to the flow rate on the secondary side, as shown in FIG. 6, instead of adjusting the preheating temperature shown in FIG. May be performed by doing. Since the rotation speed of the circulation pump 130 and the flow rate on the primary side are substantially proportional to each other, the flow rate on the primary side can be made appropriate according to the flow rate on the secondary side by such an instruction.

  Returning to FIG. 4, following step S24, the control unit 11 determines whether the preheating flow rate is smaller than the threshold value (step S25). This threshold is equal to the threshold used in step S23.

  When it is determined that the preheating flow rate is not smaller than the threshold value (step S25; No), the control unit 11 repeats the processing from step S24. On the other hand, when it is determined that the preheating flow rate is smaller than the threshold value (step S25; Yes), the control unit 11 enters the standby state and repeats the processing from step S23.

(Heating operation processing)
Next, the heating operation process executed by the controller 22 of the second heating unit 220 in the preheating hot water supply mode will be described with reference to FIG. 7.

  First, the control unit 22 determines whether the flow rate of the second heating unit 220 exceeds the threshold value (step S31). Specifically, the control unit 22 determines whether or not the measured value by the flow rate sensor 224 exceeds a certain flow rate that can be stably detected by the flow rate sensor 224.

  When determining that the flow rate does not exceed the threshold value (step S31; No), the control unit 22 repeats the determination of step S31. On the other hand, when determining that the flow rate exceeds the threshold value (step S31; Yes), the control unit 22 ignites the burner (step S32). Thereby, heat exchange by the heat exchanger 221 is started, and the city water flowing into the heat exchanger 221 is heated.

  Next, the control unit 22 controls the burner, the adjusting valve 225 and the bypass valve 226 to adjust the hot water supply temperature (step S33). Specifically, the control unit 22 obtains the temperature of the hot water flowing out of the heat exchanger 221 from the temperature sensor 228, and controls the burner combustion amount so that this temperature approaches the target value. Further, the control unit 22 controls the opening amount of the control valve 225 to control the amount of water flowing into the second heating unit 220, and controls the opening amount of the bypass valve 226 to control the amount of water flowing to the bypass passage. Adjust to make hot water temperature equal to the set value.

  The hot water whose hot water supply temperature has been adjusted by the second heating unit 220 returns to the hot water storage unit 100 through the hot water discharge pipe, is decompressed by the pressure reducing valve 170, and then is supplied from the hot water supply port 102 via the hot water supply switching valve 180.

  Next, the control unit 22 determines whether the flow rate of the second heating unit 220 is smaller than the threshold value (step S34). This threshold is equal to the threshold used in step S31. When it is determined that the flow rate is not smaller than the threshold value (step S34; No), the control unit 22 repeats the processing from step S32. On the other hand, when it is determined that the flow rate is smaller than the threshold value (step S34; Yes), the control unit 22 extinguishes the burner (step S35), enters the standby state, and repeats the processing from step S31.

  When the operation process in the preheated hot water supply mode is being executed, hot water supply switching valve 180 connects decompression valve 170 and hot water supply inlet 102 to shut off the flow path connecting mixing valve 140 and hot water supply inlet 102. . Therefore, the hot water of hot water storage tank 120 is not supplied to hot water supply port 102.

  Further, in the operation process of the preheating hot water supply mode by the control unit 11, the adjustment of the rotation speed of the circulation pump 130 may be realized by adjusting the temperature of the city water after preheating measured by the temperature sensor 162 to the target value. Good. When the rotation speed of the circulation pump 130 increases, the heat exchange amount of the heat exchanger 160 increases and the preheating temperature increases. The higher the preheating temperature, the smaller the heating amount to be heated by the second heating unit 220 for the same hot water supply temperature, so that the fuel consumption amount can be saved. On the other hand, if the preheating temperature becomes excessively high, the incoming water temperature of the second heating unit 220 becomes high, and the hot water supply temperature cannot be adjusted by the second heating unit 220, or the combustion may stop. Therefore, for example, the control unit 11 may adjust the rotation speed of the circulation pump 130 so that the target value of the preheating temperature becomes equal to the upper limit value of the incoming water temperature of the second heating unit 220. This upper limit is, for example, 30 ° C.

  Further, if the flow rate on the primary side of the heat exchanger 160 is controlled so that the preheating temperature becomes equal to the target value, compared to the case where ΔTwL shown in FIG. The temperature of the water returned to the hot water storage tank 120 becomes high, and the water entering temperature of the first heating unit 210 becomes high during the subsequent boiling operation. If a refrigerant that condenses on the high pressure side, such as HFC, HC, HFO, etc., is adopted, compared to a refrigerant that does not condense on the high pressure side and enters a supercritical state, such as CO2, energy consumption efficiency increases with increasing water temperature. Is less likely to decrease. Therefore, the method of controlling the flow rate on the primary side so that the preheating temperature becomes equal to the target value is particularly effective when a refrigerant that condenses on the high pressure side is used.

(Water filling operation processing)
Next, the filling operation processing executed by the control unit 22 will be described with reference to FIG. The filling operation is an operation of supplying a fixed amount of hot water to the bathtub 50. When an instruction to start the filling operation is input to the terminal 40, the terminal 40 transmits a filling instruction to the control unit 22 and the filling operation is started.

  First, the control unit 22 determines whether or not there is a filling instruction from the terminal 40 (step S41). When it is determined that there is no filling command (step S41; No), the control unit 22 enters the standby state and repeats the determination of step S41.

  On the other hand, when it is determined that the water filling command has been issued (step S41; Yes), the control unit 22 opens the water filling valve 227 (step S42) and ignites the burner (step S43). As a result, the preheated city water flows into the second heating unit 220, passes through the control valve 225, and then branches, one of which is heated by the heat exchanger 221 and the other of which joins after passing through the bypass passage. . Then, the combined hot water passes through the hot water filling valve 227 and is supplied to the bathtub 50 from both the outgoing pipe and the return pipe.

  Next, the control unit 22 controls the burner, the adjusting valve 225 and the bypass valve 226 to adjust the hot water supply temperature (step S44). Specifically, control unit 22 controls the combustion amount of the burner so that the hot water supply temperature measured by temperature sensor 228 becomes equal to the preset target value of the hot water filling temperature. The control unit 22 also controls the opening degree of the control valve 225 to control the amount of water flowing into the second heating unit 220. Further, control unit 22 controls the opening degree of bypass valve 226 to adjust the amount of water flowing in the bypass passage so that the hot water supply temperature is equal to the target value.

  Next, the control unit 22 determines whether or not the hot water supply amount exceeds the hot water filling target value (step S45). This hot water supply amount can be obtained by integrating the measurement values of the flow rate sensor 224. The control unit 22 may use the output of the water level sensor that detects the water level of the bathtub 50 to determine whether the amount of hot water supply exceeds the target value for filling water.

  When it is determined that the hot water supply amount does not exceed the target filling value (step S45; No), the control unit 22 repeats the processing from step S42. On the other hand, when determining that the amount of hot water supply exceeds the target value for filling water (step S45; Yes), the control unit 22 extinguishes the burner (step S46) and closes the filling valve 227 (step S47). Then, the control unit 22 ends the hot water filling operation process.

  When the hot water filling operation is executed, the control unit 11 of the hot water storage unit 100 executes the operation process of the preheating hot water supply mode shown in FIG. 4 regardless of the amount of heat stored in the hot water storage tank 120. As a result, the capacity of the hot water storage tank 120 does not require the amount of hot water for filling. Therefore, the hot water storage type water heater 1000 can be configured using the hot water storage tank 120 having a small capacity.

  Further, when a general hot water supply load occurs during the hot water filling operation, the tank hot water supply mode operation is executed at the same time as the hot water filling operation when the heat storage amount of the hot water storage tank 120 is larger than a preset threshold value. When the amount is smaller than this threshold value, the preheating hot water supply mode operation is executed at the same time as the hot water filling operation.

(Additional heating / warm operation)
Next, the additional heating / heat retention operation executed by the control unit 22 will be described. When a warming command to keep the hot water of the bathtub 50 at a constant temperature is input to the terminal 40, or when a reheating command to reheat the hot water stored in the bathtub 50 is input, the control unit 22 Perform reheating / heat retention operation.

  In the reheating / warming operation, the control unit 22 closes the hot water filling valve 227 and operates the pump 223. As a result, a water flow is generated from the bathtub 50 in the circulation path that returns to the bathtub 50 through the return pipe, the pump 223, the heat exchanger 222, and the forward pipe. Then, the control unit 22 ignites the burner and causes the heat exchanger 222 to reheat the hot water. In the reheating / heat-retaining operation, the operation process in the preheating hot water supply mode is not executed.

(Simultaneous operation of hot water storage operation and preheating hot water supply mode operation)
Next, a case where the hot water storage operation and the preheating hot water supply mode operation are simultaneously performed will be described. This simultaneous operation is started when the operation in the preheated hot water supply mode is started during the hot water storage operation, or when the hot water storage operation is started during the operation in the preheated hot water supply mode.

  FIG. 9 shows an actuator control method for hot water storage unit 100 when the simultaneous operation is executed. Generally, the flow rate on the secondary side of the heat exchanger 160 is about 15 to 20 L / min at the maximum, and the flow rate on the primary side also increases according to the flow rate on the secondary side. On the other hand, the amount of water flowing into the first heating unit 210 during the hot water storage operation is about 1.15 L when the city water temperature in winter is 9 ° C., the hot water storage temperature is 65 ° C., and the heating capacity is 4.5 kW. / Min.

  Therefore, it is necessary to operate the circulation pump 130 to independently control the amount of water entering the first heating unit 210 and the amount of inflow on the primary side of the heat exchanger 160. Further, it is necessary to send a part of the primary side water used for preheating to the first heating unit 210 and return the rest to the hot water storage tank 120.

  Therefore, as shown in FIG. 9, the control unit 11 controls the rotation speed of the circulation pump 130 so that the temperature difference ΔTwL becomes equal to the target value. Further, the control unit 11 controls the suction switching valve 131 so that the flow path connected to the heat exchanger 160 is fully opened. Further, control unit 11 controls the opening degree of discharge switching valve 132 so that the hot water outlet temperature becomes equal to the target value by adjusting the boiling flow rate of first heating unit 210.

  FIG. 10 shows the relationship between the opening degree of the discharge switching valve 132 and the flow rate. In FIG. 10, a line L11 indicates the flow rate from the discharge switching valve 132 to the hot water storage tank 120 side, and a line L12 indicates the flow rate from the discharge switching valve 132 to the first heating unit 210 side. As shown in FIG. 10, when the opening step of the discharge switching valve 132 changes from zero to a maximum of 100, the total of the flow rate on the hot water storage tank 120 side and the flow rate on the first heating unit 210 side becomes 100%. Then, the flow rate ratio changes.

  Therefore, when the actuator is controlled as shown in FIG. 9, the circulation pump 130 adjusts the flow rate required for the primary side of the heat exchanger 160, and the discharge switching valve 132 is boiled by the first heating unit 210. The ratio of the flow rate required for raising and the remaining flow rate returning to the hot water storage tank 120 will be adjusted.

(High temperature boiling operation process)
Next, the high temperature boiling operation process of the hot water storage tank 120 will be described with reference to FIG.

  If the stored water in the hot water storage tank 120 stays in the hot water storage tank 120 for a long time, various bacteria may propagate in the stored water, which is not preferable. If city water is sterilized with chlorine, the propagation of various bacteria is suppressed, but once heated, the water temperature of about 20 to 45 ° C., for example, may cause Legionella bacteria to reproduce. When the hot water storage tank 120 is a closed type and clean city water is constantly supplied, it can be said that there is almost no possibility that bacteria will propagate. However, considering an unexpected situation due to some external factor, when the temperature stays at a temperature at which miscellaneous bacteria can grow for a long period of time, the hot water in the hot water storage tank 120 is heated again to a high temperature at which it can be sterilized. There is a need to. This temperature is, for example, 60 ° C. or higher.

  Therefore, hot water storage type water heater 1000 according to the present embodiment executes the high temperature boiling operation shown in FIG. 11. The high temperature boiling operation is started when the hot water storage type water heater 1000 becomes operable. It is desirable to execute this high-temperature boiling operation in a time period before a large load of hot water supply occurs. This time period is, for example, a time period of 15:00 to 18:00.

  First, control unit 11 determines whether or not the amount of hot water supplied from hot water storage tank 120 to hot water supply port 102 within a preset time exceeds the capacity of hot water storage tank 120 (step S51). That is, control unit 11 determines whether hot water in hot water storage tank 120 is retained. This retention means that the water is stored in the hot water storage tank 120 for a relatively long time set in advance without being reheated. The preset time is 72 hours, for example.

  The amount of hot water discharged from the hot water storage tank 120 to the hot water supply port 102 is calculated by integrating the hot water supply flow rate measured by the flow rate sensor 192 and then measuring the hot water discharge temperature from the hot water storage tank 120 by the temperature sensor 141 and the temperature sensor 111. It can be obtained by estimating the mixing ratio of the mixing valve 140 from the relationship between the temperature of the city water and the hot water supply temperature measured by the temperature sensor 191. The amount of hot water discharged may be obtained by providing a flow rate sensor on the water pipe connecting the upper part of hot water storage tank 120 and the inlet of mixing valve 140 and integrating the measured values of this flow rate sensor.

  When the determination in step S51 is negative (step S51; No), the control unit 11 determines that the water in the hot water storage tank 120 does not stay, and ends the high temperature boiling operation without boiling the hot water. .

  On the other hand, when the determination in step S51 is affirmative (step S51; Yes), control unit 11 determines that water is retained in hot water storage tank 120 for a long time, and controls hot water supply switching valve 180. Thus, hot water supply port 102 and second heating unit 220 are communicated with each other. Then, control unit 11 sets the operation mode to the preheating hot water supply mode (step S52).

  Next, the control unit 11 determines whether or not the current time is before the specific time of midnight (step S53). The specific time is set in advance as, for example, 23:00 when the electricity rate becomes low.

  When it is determined that the current time is before the specific time (step S53; Yes), the control unit 11 determines whether the heat storage amount of the hot water storage tank 120 is smaller than the threshold value (step S54). This threshold value is equal to the threshold value for starting the hot water storage operation.

  When it is determined that the heat storage amount is not lower than the threshold value (step S54; No), the control unit 11 repeats the processing from step S53. On the other hand, when it is determined that the heat storage amount is lower than the threshold value (step S54; Yes), the control unit 11 determines whether the hot water storage temperature of the hot water storage tank 120 is lower than a specific temperature (step S55). Here, the hot water storage temperature of the hot water storage tank 120 is an average temperature of water in the hot water storage tank 120, and can be obtained from the measured values of the temperature sensors 121 to 124.

  The specific temperature used for the determination in step S55 will be described with reference to FIG. FIG. 12 shows the relationship between the incoming water temperature of the first heating unit 210 and COP (Coefficient Of Performance) as energy consumption efficiency. However, the boiling temperature is a preset constant temperature, for example, 65 ° C. The higher the incoming water temperature of the first heating unit 210, the higher the refrigerant temperature at the condenser outlet and the lower the COP. Therefore, if the high temperature boiling operation is executed in a state where the hot water having a relatively high temperature remains in the hot water storage tank 120, the COP becomes low.

  By the way, the hot water storage type water heater 1000 according to the present embodiment mainly consumes electric power to boil the hot water, and the shortage of hot water is generated by the combustion-type second heating unit 220. Electric power is generated, for example, by burning fossil fuel in a thermal power plant. Here, the primary energy efficiency can be used to evaluate the first heating unit 210 with the same evaluation index as the second heating unit 220 that directly inputs the fuel.

  The primary energy efficiency of the electricity finally consumed at home is about 36.9% with respect to the fossil fuel input at the power plant. The heat pump type first heating unit 210 can absorb heat from the atmosphere and obtain hot water supply heat that is equal to or higher than the input electric energy. Therefore, the primary energy efficiency of the first heating unit 210 can be obtained by multiplying the primary energy efficiency of electric energy by COP.

  On the other hand, the hot water supply combustion efficiency of the combustion-type second heating unit 220 is about 95% even with high efficiency. Since the second heating unit 220 directly inputs the fossil fuel, its combustion efficiency can be regarded as the primary energy efficiency of hot water supply.

  Therefore, in order for the primary energy efficiency of the first heating unit 210 to be higher than the primary energy efficiency of the second heating unit 220, COP may be greater than 2.57 (= 95 / 36.9).

  Specifically, as shown in FIG. 12, from the relationship between the water input temperature of the first heating unit 210 and the COP, the water input temperature Twi at which the primary energy efficiency of the first heating unit 210 becomes equal to that of the second heating unit 220. Can be asked. Then, the specific temperature used in the determination of step S55 in FIG. 11 may be set as the water temperature Twi.

  When it is determined that the hot water storage temperature is not lower than the specific temperature (step S55; No), the control unit 11 repeats the processing from step S53. Thus, the operation process in the preheating hot water supply mode is executed. As a result, the water temperature in the hot water storage tank 120 decreases. As a result, it is possible to improve the energy efficiency when the additional heating operation (step S56) and the subsequent heating operation (step S57) are executed.

  On the other hand, when it is determined that the hot water storage temperature is lower than the specific temperature (step S55; Yes), the control unit 11 executes the high temperature boiling operation of the hot water storage tank 120 (step S56). This high-temperature boiling operation is an operation in which the boiling temperature is set to, for example, 65 ° C., which is higher than the boiling temperature in the hot water storage operation, and the amount of heat required on the day is predicted and boiling is performed. After that, the control unit 11 repeats the processing from step S53.

  When it is determined in step S53 that the current time is not before the specific time of midnight (step S53; No), the control unit 11 executes the high temperature boiling operation (step S57). In this high-temperature boiling operation, the entire amount of the hot water storage tank 120 is heated to a temperature at which it can be sterilized, regardless of the hot water supply load expected on the next day. The high temperature boiling operation is executed in place of the hot water storage operation executed at midnight.

  Here, when the boiling temperature is set to 65 ° C., the hot water storage operation is executed, and the amount of heat stored in the hot water storage tank 120 increases, the water inlet temperature of the first heating unit 210 gradually rises. In the first heating unit 210 of the heat pump type, it is conceivable that when the temperature of the incoming water rises, the pressure on the high-pressure side rises and exceeds the allowable pressure.

  Therefore, for example, when the incoming water temperature of the first heating unit 210 exceeds the upper limit value of 50 ° C., the operation of the compressor 211 is stopped, only the circulation pump 130 is operated, and the temperature of the bottom of the hot water storage tank 120 is 60 ° C. The hot water in the lower part of the hot water storage tank 120 may be circulated to the upper part. In this case, since the compressor 211 is stopped, the heating by the first heating unit 210 is not executed, but the hot water in the upper part of the hot water storage tank 120 and the low temperature water in the lower part are mixed, and the temperature of the entire hot water storage tank 120 is reduced. The temperature may be 60 ° C or higher.

  When the temperature of the entire hot water storage tank 120 becomes equal to or higher than the sterilizable temperature, the control unit 11 ends the high temperature boiling operation process.

(Example of driving operation)
Next, an example in which the hot water supply load, the amount of heat stored in the hot water storage tank 120, and the heating capacities of the first heating unit 210 and the second heating unit 220 change over a day will be described with reference to FIG.

  The heat storage amount of the hot water storage tank 120 is increased by executing the hot water storage operation during the midnight time when the electricity rate is low. The heat storage amount at the end time of the midnight time zone may be the maximum value capable of storing heat in the hot water storage tank 120, or may correspond to the expected hot water supply load. In the example shown in FIG. 13, the end time of the midnight time zone is 7:00.

  From 7:00 to 18:00, general hot water supply load occurs in the bathroom and faucet of the kitchen. Since this general hot water supply load is smaller than the hot water supply load generated by bathing, the operation process in the tank hot water supply mode is executed. During the time when the general hot water supply load is not generated, the heat storage amount is gradually reduced due to the heat radiation from the hot water storage tank 120.

  The filling operation is executed around 19:00. At this time, since the operation process of the preheated hot water supply mode is executed, the reduction of the heat storage amount of the hot water storage tank 120 and the heating by the second heating unit 220 occur at the same time. When the hot water filling operation is executed, the amount of heat stored in hot water storage tank 120 is significantly reduced and becomes lower than threshold value TH1 for controlling hot water supply switching valve 180. That is, the operation mode shifts from the tank hot water supply mode to the preheat hot water supply mode. After that, a general hot water supply load represented by a shower occurs, but the operation processing in the preheated hot water supply mode continues until the heat storage amount of the hot water storage tank 120 falls below the threshold value TH2 for executing the hot water storage operation.

  When the general hot water supply load is continuously generated and the heat storage amount of the hot water storage tank 120 falls below the threshold value TH2, the first heating unit 210 starts the hot water storage operation. If the general hot water supply load occurs before the heat storage amount becomes larger than the threshold value TH2, the operation process in the preheat hot water supply mode is executed. The target value of the heat storage amount of hot water storage tank 120 is set to the hot water supply load that is expected to occur after the current time on the day. This target value is usually smaller than the target value for hot water storage operation during the midnight time.

  When a general hot water supply load occurs after the hot water storage operation ends, the tank hot water supply mode operation is executed when the heat storage amount of the hot water storage tank 120 is larger than the threshold value TH1, and the preheat hot water supply mode operation is executed when the heat storage amount is smaller than the threshold value TH1. To be done. It is desirable to control the heat storage amount so that it becomes the lowest at 24:00, which is the end time of the day, but if the occurrence of a general hot water supply load is predicted after 24:00, at 24:00 The heat storage amount may be left to some extent.

  As described above, in hot water storage water heater 1000 according to the present embodiment, even if water stays in hot water storage tank 120 for a long time and it is necessary to perform the high temperature boiling operation, the operation in the preheating hot water supply mode is performed. By executing the above, the heat storage of the hot water storage tank 120 can be utilized.

  Further, hot-water storage type hot water supply device 1000 executes an operation process in the preheated hot-water supply mode to execute the high temperature boiling operation after the water temperature of hot water storage tank 120 decreases. Therefore, when the high-temperature boiling operation is executed, the incoming water temperature of the heat pump type first heating unit 210 can be lowered. Therefore, the overall primary energy efficiency can be increased.

  Further, hot water storage type hot water supply device 1000 executes a high temperature boiling operation that increases the amount of heat stored in hot water storage tank 120 under conditions that require sterilization. Therefore, the amount of increase of the medium temperature water is small, and the energy consumption efficiency of the high temperature boiling operation executed at midnight of the day can be increased. In the high-temperature boiling operation at midnight, of the total amount stored in the hot water storage tank 120, the remaining hot water that cannot be boiled in the high-temperature boiling operation may be boiled.

  Further, when the amount of heat storage in hot water storage tank 120 is sufficient to cover the general hot water supply load, hot water is directly supplied from hot water storage tank 120 to hot water supply port 102, and low-temperature city water flows into the lower portion of hot water storage tank 120. Therefore, the energy consumption efficiency of the first heating unit 210 during the hot water storage operation can be increased. In particular, when CO2 is used as the refrigerant, the high pressure side becomes a supercritical cycle, and the energy consumption efficiency becomes higher as the water inlet temperature of the first heating unit 210 becomes lower, which is effective.

  Further, the hot water storage unit 100 has a flow rate sensor 163 that measures the flow rate of city water, and the second heating unit 220 has a flow rate sensor 224 that measures the flow rate of inflowing city water. Therefore, when preheating the city water flowing into the second heating unit 220 with the hot water storage unit 100, there is no need for communication between the control unit 11 of the hot water storage unit 100 and the control unit 22 of the second heating unit 220, and they are independent of each other. Then, the actuators of the hot water storage unit 100 and the second heating unit 220 can be controlled.

Embodiment 2.
Next, the second embodiment will be described focusing on the differences from the above-described first embodiment. In addition, about the same or equivalent structure as the said Embodiment 1, the same code | symbol is used and the description is abbreviate | omitted or simplified. Hot water storage water heater 1000 according to the present embodiment differs from that according to the first embodiment in that its constituent elements are controlled by one controller that executes a program.

  FIG. 14 shows the configuration of hot water storage type water heater 1000 according to the present embodiment. As shown in FIG. 14, hot water storage type water heater 1000 has controller 60 that controls hot water storage unit 100, first heating unit 210, and second heating unit 220.

  The controller 60 is configured as a computer including a processor 61, a main storage unit 62, an auxiliary storage unit 63, an input unit 64, an output unit 65, and a communication unit 66. The main storage unit 62, the auxiliary storage unit 63, the input unit 64, the output unit 65, and the communication unit 66 are all connected to the processor 61 via an internal bus 67.

  The processor 61 includes an MPU (Micro Processing Unit). By executing the program 68 stored in the auxiliary storage unit 63, the processor 61 exhibits the same function as that of the control units 11, 21, 22 according to the first embodiment.

  The main storage unit 62 includes a RAM (Random Access Memory). The main storage unit 62 loads the program 68 from the auxiliary storage unit 63. The main storage unit 62 is used as a work area of the processor 61.

  The auxiliary storage unit 63 is configured to include a nonvolatile memory such as an HDD (Hard Disk Drive) or a flash memory. The auxiliary storage unit 63 stores, in addition to the program 68, various data used for the processing of the processor 61.

  The input unit 64 includes, for example, an input key and a capacitance type pointing device. The input unit 64 acquires the information input by the user and notifies the processor 61 of the information. The output unit 65 includes a display device represented by an LCD (Liquid Crystal Display), for example. The output unit 65 forms a touch screen by being integrally formed with the pointing device that forms the input unit 64, for example. Since terminal 40 corresponds to a user interface of hot water storage type water heater 1000, controller 60 may be configured by omitting input unit 64 and output unit 65.

  The communication unit 66 includes a communication interface circuit for communicating with an external device. The communication unit 66 notifies the processor 61 of information included in a signal received from the outside, and transmits a signal for transmitting the information output from the processor 61 to an external device. The information acquired from the outside by the communication unit 66 includes the measurement results of the sensors of the hot water storage unit 100, the first heating unit 210, and the second heating unit 220. The information transmitted to the outside by the communication unit 66 includes instructions for the pumps and valves of the hot water storage unit 100, the first heating unit 210, and the second heating unit 220.

  In the present embodiment, hot water storage unit 100 is configured by omitting control unit 11 (see FIG. 1), and first heating unit 210 is configured by omitting control unit 21 (see FIG. 1). The heating unit 220 is configured by omitting the control unit 22 (see FIG. 1).

  As described above, hot-water storage hot water supply device 1000 according to the present embodiment has controller 60 that controls its constituent elements. This facilitates maintenance and management of the program executed by the controller 60.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

  For example, the flow rate sensor 163 that measures the flow rate on the secondary side of the heat exchanger 160 may be provided near the secondary side outlet instead of near the secondary side inlet.

  Further, the user may be allowed to input a command to start the high temperature boiling operation from the terminal 40. For example, in a home equipped with a solar power generation device, there may be a case where fine weather occurs and surplus power is generated during the day. In this case, for example, if it is predicted that the hot water storage tank 120 needs to be sterilized within 24 hours after the current time, the terminal 40 notifies the user that the high temperature boiling operation needs to be performed, and the surplus power is used. High temperature boiling operation may be promoted. As a result, it is possible to suppress an increase in running cost even when the input power increases due to the execution of the high temperature boiling operation.

  Further, a controller of a HEMS (Home Energy Management System) including hot water storage type hot water supply device 1000 may predict the generation of surplus power, and may instruct hot water storage type hot water supply device 1000 to perform a high temperature boiling operation for sterilization.

  Further, the programs stored in the EEPROMs of the control units 11, 21, 22 and the program 68 stored in the auxiliary storage unit 63 are stored in a flexible disk, a CD-ROM (Compact Disk Read-Only Memory), a DVD ( Digital Versatile Disk) and MO (Magneto-Optical disk), which are stored in a computer-readable recording medium and distributed, and the programs are installed in a computer to configure an apparatus that executes the above-described processing. You can

  Alternatively, the program may be stored in a disk device included in a server device on a communication network typified by the Internet, and may be superimposed on a carrier wave and downloaded to a computer, for example.

  The above-described processing can also be achieved by starting and executing the program while transferring the program through a network typified by the Internet.

  Further, the above-described processing can be achieved by causing all or part of the program to be executed on the server device and executing the program while the computer transmits and receives information regarding the processing via the communication network.

  When the OS (Operating System) shares the above functions or when the OS and applications cooperate with each other, only the parts other than the OS may be stored in a medium and distributed. Also, it may be downloaded to a computer.

  Further, the means for realizing the function of hot water storage type water heater 1000 is not limited to software, and a part or all of the means may be realized by dedicated hardware. For example, if a circuit represented by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) is used, power saving of the hot water storage water heater 1000 can be achieved.

  The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Further, the above-described embodiments are for explaining the present invention, and do not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the scope of the claims. Various modifications made within the scope of the claims and the scope of the invention equivalent thereto are considered to be within the scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a technique of supplying hot water generated by heating city water.

  1000 hot water storage type water heater, 11 control part, 100 hot water storage unit, 101 water supply port, 102 hot water supply port, 110 water supply pipe, 111, 121-124, 141, 161, 162, 191 temperature sensor, 112, 170 pressure reducing valve, 120 hot water storage Tank, 130 circulation pump, 131 intake switching valve, 132 discharge switching valve, 140 mixing valve, 160 heat exchanger, 163, 192 flow rate sensor, 180 hot water supply switching valve, 190 hot water supply pipe, 210 first heating unit, 21 control unit, 211 compressor, 212 heat exchanger, 213 expansion valve, 214 evaporator, 220 second heating unit, 22 control unit, 221, 222 heat exchanger, 223 pump, 224 flow rate sensor, 225 control valve, 226 bypass valve, 227 Hot water valve, 228 Temperature sensor, 40 terminal, 50 bathtub, 60 controller, 61 processor, 62 main storage unit, 63 auxiliary storage unit, 64 input unit, 65 output unit, 66 communication unit, 67 internal bus, 68 program, L1, L2, L11, L12 line.

Claims (4)

A first heating means for generating the first hot water of the first temperature by heating water,
A hot water storage tank for storing the said water first water,
A heat exchanger that preheats the city water by heat exchange between the first hot water taken from the hot water storage tank and the city water;
Second heating means for heating the city water preheated by the heat exchanger to generate second hot water ;
Control means for supplying the second hot water to the hot water supply port when the amount of the first hot water supplied from the hot water storage tank to the hot water supply port within a preset time is smaller than the capacity of the hot water storage tank; Equipped with
The first heating means stores water stored in the hot water storage tank when the amount of the first hot water supplied from the hot water storage tank to the hot water supply port within the preset time is smaller than the capacity. And when the average temperature of the first hot water is lower than a threshold value, the water taken from the hot water storage tank is heated to generate the first hot water having a second temperature higher than the first temperature,
When the temperature of the water flowing into the first heating means exceeds the upper limit value, the control means stops the heating by the first heating means and operates the pump to move the hot water in the lower part of the hot water storage tank to the upper part. A hot-water storage water heater that circulates . The threshold is a temperature at which the primary energy efficiency of the first heating means becomes equal to the primary energy efficiency of the second heating means,
The hot water storage type water heater according to claim 1 . A hot water storage step of storing a first hot water of the first temperature produced by heating the intake water from the hot water storage tank to the hot water storage tank,
When the amount of the first hot water supplied from the hot water storage tank to the hot water supply port within a preset time is smaller than the capacity of the hot water storage tank, the first hot water taken from the hot water storage tank and city water A hot water supply step of preheating the city water by heat exchange and supplying the second hot water generated by heating the preheated city water to the hot water supply port;
When the average temperature of the water stored in the hot water storage tank and the first hot water becomes lower than a threshold value, the water taken from the hot water storage tank is heated to increase the first temperature of the second temperature higher than the first temperature. A generating step for generating hot water,
When the temperature of the water flowing into the heating means for generating the first hot water exceeds the upper limit value, the heating by the heating means is stopped and the pump is operated to circulate the hot water in the lower part of the hot water storage tank to the upper part. Circulation step,
Hot water supply method including. The hot-water storage type water heater with a hot water storage tank,
The first hot water having a first temperature generated by heating the water taken from the hot water storage tank is stored in the hot water storage tank,
If the amount of the first hot water supplied to the hot water storage tank or al supply sprue within the preset time is smaller than the capacity of the hot water storage tank, the first hot water and city that intake from the previous SL hot water storage tank The city water is preheated by heat exchange with water, and the second hot water generated by heating the preheated city water is supplied to the hot water supply port,
When the average temperature of the water stored in the hot water storage tank and the first hot water becomes lower than a threshold value, the water taken from the hot water storage tank is heated to increase the first temperature of the second temperature higher than the first temperature. Generate hot water,
When the temperature of the water flowing into the heating means for generating the first hot water exceeds the upper limit value, the heating by the heating means is stopped and the pump is operated to circulate the hot water in the lower part of the hot water storage tank to the upper part. ,
A program that lets you do things.

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