Heat pump water heater

Abstract

To provide a heat pump water heater advantageous to improvement of capacity responding to night-time shortage of hot water and more efficient utilization of surplus electric power for a boiling-up operation.SOLUTION: A heat pump water heater performs: a first boiling-up operation for boiling up hot water in a hot water storage tank with a first heating capacity by using electric power supplied from a commercial power supply in a first time zone; and a second boiling-up operation for boiling up the hot water in the hot water storage tank by using surplus electric power obtained by subtracting use electric power of the other apparatus from electric power supplied from a natural energy power generator in a second time zone. The second boiling-up operation includes a surplus electric power boiling-up mode of selecting a heating capacity that maximizes total electric power consumption used for the boiling-up operation in the second time zone from a plurality of different heating capacities. In the case of an operation in the surplus electric power boiling-up mode, the heating capacity in the first time zone is changed to a heating capacity larger than the first heating capacity, and the first boiling-up operation is performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a heat pump water heater. [Background technology]

[0002] As a conventional technique, Patent Document 1 discloses a control method for a water heater that changes the heating capacity during the day in order to utilize power generated by solar power generation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7108220 Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional storage-type water heater described in Patent Document 1, which is designed to utilize electricity generated by solar power generation, can effectively utilize surplus electricity during the day, but has the problem that it needs to reduce the amount of water heated at night, which reduces its ability to withstand hot water shortages when instantaneously supplying hot water.

[0005] The present disclosure has been made to solve the above-mentioned problems. The purpose of the present disclosure is to provide a heat pump water heater that is advantageous in achieving both improved resistance to hot water shortages at night and more effective use of surplus electricity for boiling water operation. [Means for solving the problem]

[0006] The heat pump water heater of the present disclosure comprises a hot water storage tank, a heating unit that heats hot water in the hot water storage tank, and a control unit that controls the heating unit, and performs a first heating operation in which hot water in the hot water storage tank is heated at a first heating capacity using electricity supplied from a commercial power source during a first time period, and a second heating operation in which, when electricity is supplied from a natural energy power generation device during a second time period other than the first time period, the hot water in the hot water storage tank is heated using surplus electricity obtained by subtracting the electricity used by other equipment from the supplied electricity.In the second heating operation, the control unit is able to select a heating capacity from among a plurality of different heating capacities, and has a surplus power heating mode that selects, depending on the amount of surplus electricity, a heating capacity from the plurality of heating capacities that will result in the largest total power consumption to be used for heating operation in the second time period.When operating in surplus power heating mode, the control unit changes the heating capacity during the first time period to a heating capacity greater than the first heating capacity and performs the first heating operation. In addition, the heat pump water heater of the present disclosure is a heat pump water heater that includes a hot water storage tank, a heating unit that heats hot water in the hot water storage tank, and a control unit that controls the heating unit, and performs a first heating operation in which hot water in the hot water storage tank is heated at a first heating capacity using electricity supplied from a commercial power source during a first time period, and a second heating operation in which hot water in the hot water storage tank is heated using surplus electricity obtained by subtracting the electricity used by other equipment from the supplied electricity when electricity is supplied from a natural energy power generation device during a second time period other than the first time period.In the second heating operation, the control unit is able to select a heating capacity from among a plurality of different heating capacities, and has a surplus power heating mode that selects a heating capacity from the plurality of heating capacities that will generate the largest total amount of heating heat in the second time period depending on the amount of surplus electricity, and when operating in surplus power heating mode, the control unit changes the heating capacity during the first time period to a heating capacity greater than the first heating capacity and performs the first heating operation. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a heat pump water heater that is advantageous in achieving both improved resistance to hot water shortages at night and more effective utilization of surplus electricity for boiling operation. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a heat pump hot water heater according to a first embodiment. [Figure 2] 4 is a flowchart showing a control operation in the first embodiment. [Figure 3] 10 is a flowchart showing a control operation in the second embodiment. [Figure 4] FIG. 2 is a conceptual diagram of operation in the first embodiment. [Figure 5] FIG. 2 is an image diagram showing the transition of daytime heating power consumption in the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of a display on a remote control device. [Figure 7] FIG. 10 is a diagram illustrating an example of a display on a remote control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. Common or corresponding elements in each drawing are designated by the same reference numerals, and descriptions thereof will be simplified or omitted. In the following description, terms such as "water," "hot water," "warm water," and "hot water" generally refer to liquid water, and may include cold water to boiling water. Furthermore, the configurations shown in the following embodiments are examples of the technical ideas of the present disclosure, and may be combined with other known technologies, or multiple technical ideas described in the present disclosure may be combined. Furthermore, parts of the configurations may be omitted or modified without departing from the spirit of the present disclosure.

[0010] Embodiment 1 FIG. 1 is a diagram illustrating a heat pump water heater according to a first embodiment. In this embodiment, the calorific value of hot water is calculated, for example, as the difference between the calorific value of hot water and the calorific value of water at the same temperature as the water supplied from the water source. Furthermore, in this embodiment, the calorific value of hot water may be described in units of the volume of hot water [L] converted into the calorific value of hot water at a predetermined reference hot water temperature. The reference hot water temperature may be, for example, 40°C. As shown in FIG. 1, the heat pump water heater according to this embodiment includes a heat pump unit 100 and a tank unit 200. The heat pump unit 100 includes components such as a compressor 1, a water-refrigerant heat exchanger 2, an expansion valve 3, and an air heat exchanger 4. These components are connected in a ring shape by piping or the like to form a refrigerant circuit 101 that circulates the refrigerant using the compressor 1. The water-refrigerant heat exchanger 2 exchanges heat between the water and the refrigerant and has a water inlet and an outlet. The water-refrigerant heat exchanger 2 heats the water flowing in through the inlet with the refrigerant and discharges the heated water through the outlet. The air heat exchanger 4 exchanges heat between the air and the refrigerant, and is equipped with a fan 5 that blows outside air.

[0011] The tank unit 200 includes a circulation pump 6a, a reheating pump 6b, a switching valve 7, a switching valve 8, a switching valve 9, a mixing valve 10, and a hot water storage tank 11. The circulation pump 6a circulates water (including heated water) through a hot water storage circuit 201 and a reheating circuit 202, which will be described later, and sends the water toward the inlet of the water-refrigerant heat exchanger 2, and constitutes a part of these circuits 201, 202. The heat pump unit 100 corresponds to a heating section that heats the hot water in the hot water storage tank 11.

[0012] Reheating pump 6b sends water from a bathtub (not shown) toward reheating heat exchanger 12. Switching valve 7 is configured, for example, by an electromagnetically driven four-way valve having four ports A, B, C, and D, and configures a switching mechanism that switches the flow path of heated water flowing out from the outlet of water-refrigerant heat exchanger 2 to switching valve 8 or low-temperature boiled water return port 11e of hot water storage tank 11.

[0013] The switching valve 8 is configured, for example, by an electromagnetically driven four-way valve having four ports E, F, G, and H, and constitutes a switching mechanism that causes water flowing in from port E to flow out to the return port 11c of the hot water storage tank 11, the high-temperature water inlet / outlet 11b, or the reheating heat exchanger 12. The switching valves 7 and 8 also constitute a switching mechanism that returns the hot water that flows out from the high-temperature water outlet 11a of the hot water storage tank 11 to the return port 11c.

[0014] The switching valve 9 is composed of an electromagnetically driven three-way valve or the like having three ports I, J, and K, and constitutes a switching mechanism that causes water flowing out from the outlet 11f of the hot water storage tank 11 or the reheating heat exchanger 12 to pass through the circulation pump 6a and flow into the water-refrigerant heat exchanger 2. The mixing valve 10 has three ports L, M, and N, and mixes water from the medium-temperature water outlet 11d of the hot water storage tank 11 and the water supply end, and causes the water to flow out to the hot water supply mixing section 15.

[0015] Hot water tank 11 stores heated water and includes high-temperature water outlet 11a located at its upper side, high-temperature water inlet 11b located at the top of hot water tank 11, reheating return port 11c located at an intermediate height of hot water tank 11, medium-temperature water outlet 11d located at an intermediate height of hot water tank 11, low-temperature boiled water return port 11e located at the bottom of hot water tank 11, outlet 11f located at the bottom of hot water tank 11, and water supply port 11g located at the lower side of hot water tank 11. Furthermore, each device mounted in tank unit 200 and water-refrigerant heat exchanger 2 are connected to each other via pipes 16a to 16h and 16j to 16q.

[0016] Specifically, the outlet of the water-refrigerant heat exchanger 2 is connected to port A of the switching valve 7 via pipe 16a. Port B of the switching valve 7 is connected to port E of the switching valve 8 via pipe 16b. Port F of the switching valve 8 is connected to the high-temperature water outlet 11a via pipes 16c and 16d. Port F is also connected to the primary-side inlet of the reheating heat exchanger 12 via pipes 16c and 16e. The primary-side outlet of the reheating heat exchanger 12 is connected to port J of the switching valve 9 via pipe 16f and to the medium-temperature water outlet 11d of the hot water storage tank 11 via pipe 16g. Port I of the switching valve 9 is connected to the outlet 11f via pipe 16h. Port K is connected to the suction port of the circulation pump 6a via pipe 16j. The discharge port of the circulation pump 6a is connected to the inlet of the water-refrigerant heat exchanger 2 via pipe 16k. Furthermore, the discharge port of the circulation pump 6a is connected to port C of the switching valve 7 via pipe 16l. Furthermore, port D of the switching valve 7 is connected to the low-temperature boiled water return port 11e of the hot water storage tank 11 via pipe 16m. Port H of the switching valve 8 is connected to the high-temperature water inlet / outlet 11b of the hot water storage tank 11 via pipes 16n and 16q. Port G is connected to the reheating return port 11c via pipe 16o. The water supply port 11g of the hot water storage tank 11 is connected to the water supply end via pipe 16p.

[0017] In the configuration of the above tank unit 200, the circulation pump 6a, the hot water storage tank 11, the piping 16a, 16b, 16h, 16j, 16k, 16m, 16n, 16q, the switching valve 7, the switching valve 8, and the switching valve 9 constitute a hot water storage circuit 201 that stores heated water flowing out from the water-refrigerant heat exchanger 2 in the hot water storage tank 11.

[0018] Furthermore, the circulation pump 6a, the reheating heat exchanger 12, the piping 16b, 16d, 16e, 16f, 16j, and 16o, the switching valve 7, the switching valve 8, and the switching valve 9 constitute a reheating circuit 202 that heats the water to be heated on the load side using the reheating heat exchanger 12. Although not shown in this embodiment, the water to be heated may be bathwater or circulating water for floor heating. The circulation pump 6a does not necessarily have to be installed in the tank unit 200 and may be mounted on the heat pump unit 100 side. Furthermore, the high-temperature water inlet / outlet 11b, the medium-temperature water outlet 11d of the hot water storage tank 11, the piping 16n and 16q, the mixing valve 10, and the hot water supply mixing unit 15 constitute a hot water supply circuit 203 that extracts hot water from the hot water storage tank 11 and supplies it to the bathtub or a hot water supply terminal.

[0019] The compressor 1 constituting the heat pump unit 100 is driven by a drive unit (not shown) equipped with, for example, an inverter-controlled DC brushless motor. This drive unit has a function of varying the pressure and temperature of the refrigerant discharged from the compressor 1. However, in the present disclosure, without using such a drive unit, for example, the heat pump unit 100 may be equipped with multiple compressors 1 and the pressure and temperature of the refrigerant may be varied by switching the number of compressors in operation. Furthermore, the compressor 1 may be equipped with a container such as a suction muffler disposed on its suction side to reduce refrigerant noise, or an oil separator for separating and recovering lubricating oil leaked to the discharge side of the compressor 1. Furthermore, the refrigerant used in the heat pump unit 100 is preferably a refrigerant capable of producing hot water at high temperatures, such as carbon dioxide, R410A, propane, or propylene, but the present disclosure is not limited to these refrigerants.

[0020] Next, the control system of the heat pump water heater will be described. Heat pump unit 100 includes inlet water temperature sensor 13a, which detects the temperature of water flowing into water-refrigerant heat exchanger 2; outlet hot water temperature sensor 13b, which detects the temperature of heated water flowing out of water-refrigerant heat exchanger 2; and outdoor air temperature sensor 13c, which detects the outdoor air temperature around heat pump unit 100. Outlet hot water temperature sensor 13b constitutes an outlet hot water temperature detection means for detecting the temperature of heated water near the outlet of water-refrigerant heat exchanger 2 (hereinafter referred to as the outlet hot water temperature). Refrigerant circuit 101 also includes discharge temperature sensor 13d, which detects the temperature of refrigerant discharged from compressor 1; suction temperature sensor 13e, which detects the temperature of refrigerant drawn into compressor 1; and evaporation temperature sensor 13f, which detects the temperature of refrigerant at the inlet or intermediate position of air heat exchanger 4. Tank unit 200 also includes multiple stored hot water temperature sensors 13g-13j, which are installed in various parts of hot water tank 11 and detect the water temperature in hot water tank 11 at their respective installation locations.

[0021] The heat pump water heater also includes a control device 14 and a control device 300, each equipped with a microcomputer having a memory and a processor. The control devices 14 and 300 receive the outputs of the temperature sensors 13a-13j and the operation details of a remote control device (remote controller) 51 operated by a user. The control devices 14 and 300 control the units 100 and 200, respectively, based on this input information. Specifically, they control the operating states of the compressor 1, the circulation pump 6a, and the reheating pump 6b, the opening of the expansion valve 3, the flow direction (switching position) of the switching valves 7, 8, and 9, and the mixing valve 10, and the like. The control devices 14 and 300 also perform a boiling operation, a reheating operation, and the like, as described below, while controlling the outlet hot water temperature and the heating capacity of the refrigerant circuit 101 during these operations.

[0022] The control device 300 and the remote control device 51 can communicate bidirectionally via wired or wireless communication. The remote control device 51 is an example of a user interface. The remote control device 51 has a display unit 51a that displays information and an operation unit 51b that is operated by a user. The remote control device 51 may also have a touch screen that functions as both the display unit 51a and the operation unit 51b. A person such as a user can remotely control the heat pump hot water heater and perform various settings by operating the remote control device 51. The display unit 51a functions as a notification unit that notifies a person such as a user of information. In this embodiment, the remote control device 51 includes the display unit 51a as notification unit. However, as a modified example, the remote control device 51 may also include other notification unit, such as a voice guidance device. The remote control device 51 may be installed on a wall in a kitchen, living room, bathroom, etc. Multiple remote control devices 51 may be capable of communicating with the control device 300. In addition to or instead of the remote control device 51, an external device such as a mobile terminal like a smartphone, a smart speaker, or a television may be configured to be used as a user interface. The control device 300 and the remote control device 51 or other user interfaces may be capable of communicating via the Internet or a local area network. In the following description, operations using the remote control device 51 may be substituted for operations using a user interface other than the remote control device 51.

[0023] In the present disclosure, the control device 14, the control device 300, and the remote control device 51 may cooperate to control the operation of the heat pump water heater. In the following description, any process described as being performed by the control device 300 may be performed solely by the control device 14, the control device 300, or the remote control device 51, or two or more of the control device 14, the control device 300, and the remote control device 51 may cooperate to perform the process. Furthermore, the control means for the heat pump water heater in the present disclosure is not limited to a configuration in which multiple control devices cooperate as in the present embodiment, but may be configured by a single control device. Furthermore, various calculation processes of the heat pump water heater may be performed by the control device 300, or calculations may be performed on a cloud connected to the control device 300 via a network, and operation instructions may be sent to the heat pump water heater.

[0024] Next, the boiling operation of the heat pump water heater will be described. In the boiling operation, the refrigerant circuit 101 and the hot water circuit 201 are operated to heat low-temperature water flowing out from the outlet 11f at the bottom of the hot water storage tank 11 using the refrigerant circuit 101, and the high-temperature heated water flowing out from the outlet of the water-refrigerant heat exchanger 2 is returned to the hot water storage tank 11 through the high-temperature water inlet / outlet 11b at the top of the hot water storage tank 11.

[0025] More specifically, in the refrigerant circuit 101, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 drops in temperature while releasing heat to the water flowing through the water-refrigerant heat exchanger 2. At this time, if the high-pressure side refrigerant pressure is equal to or lower than the critical pressure, the refrigerant releases heat while liquefying. The high-pressure, low-temperature refrigerant flowing out of the water-refrigerant heat exchanger 2 is reduced in pressure to a low-pressure gas-liquid two-phase state by passing through the expansion valve 3. This refrigerant then absorbs heat from the outside air while flowing through the air heat exchanger 4, thereby evaporating and gasifying. The low-pressure refrigerant flowing out of the air heat exchanger 4 is drawn into the compressor 1 and circulated, forming a refrigeration cycle.

[0026] On the hot water storage circuit 201 side, the switching valve 7 interconnects the pipes 16a and 16b, the switching valve 8 interconnects the pipes 16b and 16n, and the switching valve 9 interconnects the pipes 16h and 16j, thereby switching to the hot water storage circuit 201. When the circulation pump 6a operates, water in the hot water storage tank 11 is introduced from the outlet 11f at the bottom of the hot water storage tank 11 through the pipes 16h, 16j, and 16k into the water-refrigerant heat exchanger 2. The water is heated (boiled) by the gas refrigerant in the water-refrigerant heat exchanger 2, becomes heated water, and flows out of the water-refrigerant heat exchanger 2. The heated water passes through the pipes 16a, the switching valve 7, the pipes 16b, the switching valve 8, the pipes 16n, and the pipes 16q, and flows into the hot water storage tank 11 from the high-temperature water inlet / outlet 11b of the hot water storage tank 11. In this way, when the boiling operation is performed, hot water is stored while maintaining a temperature distribution state in which the upper part of the hot water storage tank 11 has high temperature water and the lower part has low temperature water.

[0027] Next, we will explain the temperature control of the heated water and the heating capacity control of the refrigerant circuit 101 that are performed during the heating operation. First, temperature control involves feedback control of the rotation speed of the circulation pump 6a so that the hot water outlet temperature of the water-refrigerant heat exchanger 2, detected by the hot water outlet temperature sensor 13b, is equal to a predetermined target hot water outlet temperature. This feedback control is performed periodically at a fixed time interval T2. During the heating operation, hot water is stored with the target hot water outlet temperature set to a predetermined target hot water outlet temperature. The target hot water outlet temperature is set based on the operation of the remote control device 51, or is set to ensure a sufficient heat storage capacity (hot water storage capacity) calculated from past hot water usage, and is set to fall within a predetermined range (e.g., 55°C to 90°C). The target hot water outlet temperature may be set by either the control device 14, the control device 300, or the remote control device 51.

[0028] The temperature control described above only controls the flow rate of heated water entering and exiting the water-refrigerant heat exchanger 2, so the maximum hot water outlet temperature achieved by the temperature control depends on the heating capacity of the refrigerant circuit 101. Therefore, the refrigerant circuit 101 is required to have a heating capacity sufficient to achieve the target hot water outlet temperature, even if it is set to the maximum value within the set range (90°C in the above example). For this reason, the heating capacity control sets a target value (target heating capacity) for the heating capacity that satisfies the above requirement based on, for example, the amount of hot water (remaining hot water) in the hot water storage tank 11, the outside air temperature, the water supply temperature, etc., and controls the rotation speed of the compressor 1 so that the actual heating capacity of the refrigerant circuit 101 matches the target heating capacity. Controlling the heating capacity in this manner ensures that the hot water temperature required by the water heater can be stably maintained regardless of changes in the target hot water outlet temperature setting and external conditions. The heating capacity control is periodically executed at a fixed time interval T1. Furthermore, the rotation speed of the compressor 1 is set to an upper and lower limit from the perspective of durability.

[0029] In addition, in the present disclosure, not only a supercritical heat pump unit in which the refrigerant pressure is equal to or higher than the critical pressure, but also a heat pump unit that operates at a pressure lower than the critical pressure may be used as the heat pump unit 100. In this case, chlorofluorocarbon gas, ammonia, etc. may be used as the refrigerant.

[0030] The heat pump water heater of this embodiment can perform a first heating operation and a second heating operation. The first heating operation is an operation in which hot water in the hot water storage tank 11 is heated at a first heating capacity using power supplied from a commercial power source during a first time period. The first time period corresponds to a nighttime period.

[0031] The second heating operation is an operation in which, when power is supplied from a natural energy power generation device during a second time period other than the first time period, surplus power obtained by subtracting the power used by other devices in the home from the supplied power is used to heat water in the hot water storage tank 11. The natural energy power generation device is, for example, a solar power generation device. The second time period corresponds to daytime hours.

[0032] The control device 300 has a surplus power boil-up mode. In the surplus power boil-up mode, a heating capacity can be selected from among a plurality of different heating capacities in the second boil-up operation. Then, depending on the amount of surplus power, the control device 300 selects from the plurality of heating capacities the heating capacity that maximizes the total amount of power consumed in the boil-up operation during the second time period. This allows for more effective use of surplus power, resulting in significant improvements in utility costs.

[0033] Furthermore, when operating in the surplus power boil-up mode, the control device 300 changes the heating capacity in the first time slot to a heating capacity greater than the first heating capacity and performs the first boil-up operation, thereby improving resistance to hot water shortages at night.

[0034] Fig. 2 is a flowchart showing the control operation in the first embodiment. In step S1 of Fig. 2, the control device 300 acquires predicted information on the electric power load in the home for the next day before starting the water heating operation in the first time slot. The electric power load in the home means the electric power load used by the electric appliances in the home other than the heat pump hot water heater.

[0035] For the predicted information on the power load within the home, actual data obtained from a smart meter or a HEMS (Home Energy Management System) controller may be used, or the data may be input by the user, or a general value may be used as a fixed value.

[0036] Next, in step S2, the surplus power for each hour of the next day is calculated based on the load prediction information acquired in step S1. The surplus power is calculated using the following formula. Surplus power = Solar power generation - In-house power load (1)

[0037] The solar-generated power used to calculate surplus power may be actual data acquired by the control device 300 via a power conditioner, or a predicted value based on meteorological data, weather forecast information, postal code (longitude and latitude information), etc. acquired by the control device 300 via a network.

[0038] The relationship between the surplus power calculated by equation (1) and the power consumption of the heat pump water heater is Surplus electricity > Power consumption by heat pump water heaters (2) When this occurs, operation will be performed in surplus power heating mode.

[0039] In the second boiling operation, one of a plurality of different heating capacities can be selected. There is no upper limit to the number of selectable heating capacities, and the number of selectable heating capacities is not limited. However, for the sake of explanation, the operation will be described assuming that the heat pump water heater is capable of selecting from three heating capacities: first heating capacity, second heating capacity, and third heating capacity.

[0040] A supplement to the power consumption of a heat pump water heater in equation (2) is provided. The power consumption of a heat pump water heater tends to vary depending on the heating capacity. Although there are differences depending on the specifications and there are peaks, generally the lower the heating capacity, the lower the power consumption tends to be. Therefore, if the heating capacity is set low, it may be possible to operate within the range of surplus power even when there is little surplus power.

[0041] Fig. 4 is a conceptual diagram of operation in the first embodiment. Fig. 5 is an image diagram showing the transition of daytime power consumption for water heating in the first embodiment. In step S3, as shown in Fig. 4, surplus times t1, t2, and t3 (corresponding to the first heating capacity, the second heating capacity, and the third heating capacity, respectively) during which power consumption at each heating capacity is within the surplus power range are calculated. Using the surplus times t1, t2, and t3, in steps S4 to S6, the amount of power consumption to be used for water heating at each heating capacity is calculated using the following formula, and the relative magnitudes of these calculations are compared to select the heating capacity that results in the largest calculated value for the amount of power consumption to be used for water heating in the second time slot. Power consumption at first heating capacity = surplus time t1 × power consumption at first heating capacity (3) Power consumption at second heating capacity = surplus time t2 × power consumption at second heating capacity (4) Power consumption at the third heating capacity = surplus time t3 × power consumption at the third heating capacity (5)

[0042] The magnitude relationships between equations (3), (4), and (5) are compared, and the heating capacity that results in the greatest amount of power consumption is adopted as the heating capacity for the second boiling operation. By adopting the heating capacity that results in the greatest amount of power consumption, it is possible to make greater use of surplus power, which is beneficial to the user in terms of utility costs.

[0043] In step S4, it is determined whether the energy consumption for boiling water at the first heating capacity in the second time period is greater than the energy consumption for boiling water at the second heating capacity or the third heating capacity. If the answer is Yes in step S4, the process proceeds to step S7. If the answer is No in step S4, the process proceeds to step S5.

[0044] In step S5, it is determined whether the energy consumption for boiling water at the second heating capacity in the second time period is greater than the energy consumption for boiling water at the first heating capacity or the third heating capacity. If the answer is Yes in step S5, the process proceeds to step S8. If the answer is No in step S5, the process proceeds to step S6.

[0045] In step S6, it is determined whether the energy consumption for boiling at the third heating capacity in the second time slot is greater than the energy consumption for boiling at the first heating capacity or the second heating capacity. If the answer is Yes in step S6, the process proceeds to step S9.

[0046] In steps S7 to S9, the target amount of hot water storage to be heated during the night of that day is determined. Heat pump water heaters generally learn the user's usage load and heat the target amount of hot water storage based on the learning results during the night when electricity rates are low. Therefore, when operating in surplus power heating mode during the daytime the following day, it is necessary to subtract the amount to be heated during the daytime the following day from the target amount of hot water storage for the nighttime and ensure free capacity in hot water storage tank 11. The amount to be heated in surplus power heating mode is calculated using the following formula. Excess boiling amount at first heating capacity = Excess time t1 × First heating capacity (6) Excess boiling amount at the second heating capacity = Excess time t2 × Second heating capacity (7) Excess boiling amount at the third heating capacity = Excess time t3 × Third heating capacity (8)

[0047] Here, the corrected target hot water storage capacity is calculated by subtracting one of the excess boiling amounts in the above equations (6) to (8) corresponding to the heating capacity determined using equations (3), (4), and (5) from the target hot water storage capacity. The calculation formula is as follows.

[0048] First corrected target hot water storage amount = target hot water storage amount - excess boiling amount at first heating capacity (9) Second corrected target hot water storage amount = target hot water storage amount - excess boiling amount at second heating capacity (10) Third corrected target hot water storage amount = target hot water storage amount - excess boiling amount at third heating capacity (11)

[0049] In the first boiling operation, the control device 300 performs the boiling operation with any one of the corrected target hot water storage amounts (9) to (11) above.

[0050] The calculations in steps S1 to S9 may be performed by the control device 300 of the heat pump water heater, or may be performed on a cloud connected to the control device 300 via a network, and operating instructions may be sent to the heat pump water heater.

[0051] Additionally, when the surplus power boiling mode is in operation, the heating capacity of the first boiling operation at night is changed from the first heating capacity to the fourth heating capacity, which has a higher heating capacity. When surplus boiling is performed the following day, the amount of hot water that should have been stored during the night is reduced, which reduces the instantaneous hot water shortage resistance. Therefore, by setting the heating capacity at night higher, the amount of hot water boiled per hour increases, which reduces the decrease in hot water shortage resistance.

[0052] Embodiment 2 Fig. 3 is a flowchart showing the control operation in embodiment 2. Fig. 3 is the same as Fig. 2 except that steps S4 to S6 in Fig. 2 are replaced with steps S11 to S13.

[0053] The basic calculation flow in the second embodiment shown in FIG. 3 is the same as that in the first embodiment shown in FIG. 1, but the method of selecting the heating capacity in the second time slot in steps S11 to S13 differs from that in the first embodiment.

[0054] To explain the specific difference, the heating capacity is selected not by the amount of power consumed for heating, but by comparing the amount of water to be heated (i.e., the amount of heat generated by heating) calculated by equations (6), (7), and (8), and the heating capacity that results in the largest calculated amount of water to be heated in the second time period is adopted as the heating capacity for the second heating operation. Adopting the heating capacity that results in the largest amount of water to be heated is beneficial for users who want to use surplus power to boil as much water as possible and keep hot water in the hot water storage tank 11.

[0055] In step S11, it is determined whether the amount of hot water boiled at the first heating capacity during the second time period is greater than the amount of hot water boiled at the second or third heating capacity. If the answer is Yes in step S11, the process proceeds to step S7. If the answer is No in step S11, the process proceeds to step S12.

[0056] In step S12, it is determined whether the amount of hot water boiled at the second heating capacity during the second time period is greater than the amount of hot water boiled at the first or third heating capacity. If the answer is Yes in step S12, the process proceeds to step S8. If the answer is No in step S12, the process proceeds to step S13.

[0057] In step S13, it is determined whether the amount of hot water boiled at the third heating capacity during the second time period is greater than the amount of hot water boiled at the first or second heating capacity. If the answer is Yes in step S13, the process proceeds to step S9.

[0058] Other than the method of selecting the heating capacity, the operation is the same as that of the first embodiment shown in FIG. 2, and therefore a description thereof will be omitted.

[0059] The control device 300 may select the lowest heating capacity if the total power consumption used for the water heating operation in the second time slot is the same for multiple heating capacities. In other words, if the calculated value of the total power consumption used for the water heating operation in the second time slot is the same for the first heating capacity, the second heating capacity, and the third heating capacity, the control device 300 may select the lowest heating capacity. As mentioned above, the power consumption consumed by a heat pump water heater tends to vary depending on the heating capacity, and generally, the lower the heating capacity, the lower the power consumption. Therefore, selecting the lowest heating capacity reduces the power consumption related to the water heating operation, which is beneficial for the user in terms of utility bills.

[0060] If the total amount of heat generated during the second time period is the same for multiple heating capacities, the lowest heating capacity may be selected. As mentioned above, selecting the lowest heating capacity reduces the amount of power consumed for heating operation, which is beneficial for the user in terms of utility costs.

[0061] The heat pump water heater may be configured so that the user can select whether to operate in surplus power heating mode using an external device such as a remote control or a mobile terminal. This allows the user to freely set or cancel the setting. This has the advantage that if the user does not want to use surplus hot water because they will be using a large amount of hot water the next morning, they can cancel the setting and use hot water without worrying about running out of hot water.

[0062] As shown in Figure 4, the control device 300 preferably controls the first boiling operation so that the end time of the boiling operation in the first time slot is the same regardless of the heating capacity. The higher the heating capacity, the shorter the time required for the boiling operation. By delaying the boiling time to make up for the shortened time and aligning the end times, heat radiation from the hot water storage tank can be suppressed for the shortened boiling time, and the amount of heat required for boiling can be reduced accordingly, which is beneficial to the user in terms of utility costs.

[0063] The target amount of hot water to be heated in the first time slot is changed before the start of the hot water heating operation depending on whether operation in surplus power boiling mode will be performed during the daytime of the following day. If surplus power boiling mode is performed, the new target amount of hot water to be heated is determined by subtracting the second target amount of hot water expected to be generated during the second time slot from the first target amount of hot water to be heated, which is the target amount of hot water to be heated when not performed. This refers to the operation described in steps S7 to S9 in Figures 2 and 3. By subtracting the amount of hot water to be heated during the daytime of the following day from the target amount of hot water stored at night in advance, the total amount of hot water to be heated for the day can be set as the user's learning amount, and there is no loss of hot water, which is beneficial to the user in terms of utility costs.

[0064] If the amount of hot water to be heated during the day the following day is not subtracted in advance from the target amount of hot water stored at night, the amount of hot water heated during the day will exceed the learned amount, resulting in a loss of hot water. Also, if the amount of hot water stored increases, the water temperature entering the heat pump during heating will rise, resulting in inefficient operation, so it is better to subtract the amount of hot water to be heated during the day the following day from the target amount of hot water stored at night in advance.

[0065] When operation in surplus power boiling mode is being performed during the second time slot, or when operation in surplus power boiling mode is scheduled for the second time slot, it is desirable to display this information on the remote control device 51 or an external device such as a mobile terminal to notify the user. Because heat pump water heaters are primarily operated at night when electricity rates are low, performing boiling operation during the daytime can cause users to feel uncomfortable and lead to inquiries to the manufacturer. FIG. 6 is a diagram showing an example of a display on the remote control device 51. By displaying on the remote control device 51 or an external device such as a mobile terminal that operation is being performed in surplus power boiling mode, as shown in FIG. 6, it is possible to prevent user misunderstanding and suppress unnecessary inquiries from the user.

[0066] If operation in the surplus power heating mode during the second time slot is possible, this may be displayed on the remote control device 51 or an external device such as a mobile terminal, allowing the user to select whether or not to perform the operation. Fig. 7 is a diagram showing an example of the display on the remote control device 51. As shown in Fig. 7, a notification is sent to the mobile terminal or the like via the display on the remote control device 51 or an app, etc., allowing the user to select whether or not to perform the operation. This can prevent the user from forgetting to set the mode.

[0067] Various aspects of the present disclosure are summarized below as appendices.

[0068] (Appendix 1) A hot water tank and a heating unit that heats the hot water in the hot water storage tank; a control unit that controls the heating unit, A heat pump water heater that performs a first heating operation in which hot water in the hot water storage tank is heated at a first heating capacity using power supplied from a commercial power source during a first time period, and a second heating operation in which, when power is supplied from a natural energy power generation device during a second time period other than the first time period, surplus power obtained by subtracting power used by other devices from the supplied power is used to heat hot water in the hot water storage tank, The control unit is capable of selecting a heating capacity from a plurality of different heating capacities in the second boiling-up operation, and is equipped with a surplus power boiling-up mode in which, according to the magnitude of the surplus power, a heating capacity from the plurality of heating capacities that results in the largest total amount of power consumed in the boiling-up operation in the second time period is selected, When operating in the surplus power boiling mode, the control unit changes the heating capacity during the first time period to a heating capacity greater than the first heating capacity, and performs the first boiling operation. (Appendix 2) A hot water tank and a heating unit that heats the hot water in the hot water storage tank; a control unit that controls the heating unit, A heat pump water heater that performs a first heating operation in which hot water in the hot water storage tank is heated at a first heating capacity using power supplied from a commercial power source during a first time period, and a second heating operation in which, when power is supplied from a natural energy power generation device during a second time period other than the first time period, surplus power obtained by subtracting power used by other devices from the supplied power is used to heat hot water in the hot water storage tank, The control unit is capable of selecting a heating capacity from among a plurality of different heating capacities in the second boiling operation, and is equipped with a surplus power boiling mode in which, according to the magnitude of the surplus power, a heating capacity from among the plurality of heating capacities that generates the largest total amount of boiling heat in the second time period is selected; When operating in the surplus power boiling mode, the control unit changes the heating capacity during the first time period to a heating capacity greater than the first heating capacity, and performs the first boiling operation. (Appendix 3) A heat pump water heater according to claim 1, wherein if the total power consumption used for the boiling operation during the second time period is the same for multiple heating capacities, the lowest heating capacity is selected. (Appendix 4) The heat pump hot water heater according to claim 2, wherein when a total amount of heat generated in the second time period is the same for a plurality of heating capacities, the lowest heating capacity is selected. (Appendix 5) A heat pump water heater according to any one of appendices 1 to 4, configured so that a user can select whether or not to operate in the surplus power heating mode using an external device such as a remote control or a mobile terminal. (Appendix 6) A heat pump water heater described in any one of Appendix 1 to Appendix 5, wherein the control unit controls the first boiling operation so that the end time of the boiling operation in the first time slot is the same regardless of the heating capacity. (Appendix 7) A heat pump water heater described in any one of Appendix 1 to Appendix 6, in which the target amount of hot water to be heated during the first time period is changed before the start of the heating operation depending on whether operation in the surplus power heating mode will be performed during the daytime the next day, and if heating in the surplus power heating mode is performed, the new target amount of hot water to be heated is a third amount of hot water to be heated, which is the first target amount of hot water to be heated, which is the target amount of hot water to be heated when heating in the surplus power heating mode is not performed, minus the second target amount of hot water expected to be generated during the second time period. (Appendix 8) A heat pump water heater according to any one of appendices 1 to 7, wherein when operation in the surplus power heating mode is being performed during the second time period, or when operation in the surplus power heating mode is scheduled during the second time period, an external device such as a remote control or a mobile terminal displays this information to notify the user. (Appendix 9) A heat pump water heater described in any one of Appendix 1 to Appendix 8, wherein if operation in the surplus power heating mode during the second time period is possible, this is displayed on an external device such as a remote control or a mobile terminal, and the user is allowed to choose whether or not to operate in the mode. [Explanation of symbols]

[0069] 2 water-refrigerant heat exchanger, 3 expansion valve, 4 air heat exchanger, 5 fan, 6a circulation pump, 6b reheating pump, 7 changeover valve, 8 changeover valve, 9 changeover valve, 10 mixing valve, 11 hot water storage tank, 11a high temperature water outlet, 11b high temperature water inlet / outlet, 11c return port, 11d medium temperature water outlet, 11e low temperature boiled water return port, 11f outlet, 11g water supply port, 12 reheating heat exchanger, 13a inlet water temperature sensor, 13b hot water outlet temperature sensor, 13c outside air temperature sensor, 13d discharge temperature sensor, 13e suction temperature sensor, 13f evaporation temperature sensor, 13g-13j hot water storage temperature sensors, 14 control device, 15 hot water supply mixing section, 16a to 16h, 16j to 16q piping, 51 remote control device, 51a display unit, 51b operation unit, 100 heat pump unit, 101 refrigerant circuit, 200 tank unit, 201 hot water storage circuit, 203 hot water supply circuit, 300 control device

Claims

1. A hot water tank and a heating unit that heats the hot water in the hot water storage tank; a control unit that controls the heating unit, A heat pump water heater that performs a first heating operation in which hot water in the hot water storage tank is heated at a first heating capacity using power supplied from a commercial power source during a first time period, and a second heating operation in which, when power is supplied from a natural energy power generation device during a second time period other than the first time period, surplus power obtained by subtracting power used by other devices from the supplied power is used to heat hot water in the hot water storage tank, The control unit is capable of selecting a heating capacity from a plurality of different heating capacities in the second boiling-up operation, and is equipped with a surplus power boiling-up mode in which, according to the magnitude of the surplus power, a heating capacity from the plurality of heating capacities that results in the largest total amount of power consumed in the boiling-up operation in the second time period is selected, When operating in the surplus power boiling mode, the control unit changes the heating capacity during the first time period to a heating capacity greater than the first heating capacity, and performs the first boiling operation.

2. A hot water tank and a heating unit that heats the hot water in the hot water storage tank; a control unit that controls the heating unit, A heat pump water heater that performs a first heating operation in which hot water in the hot water storage tank is heated at a first heating capacity using power supplied from a commercial power source during a first time period, and a second heating operation in which, when power is supplied from a natural energy power generation device during a second time period other than the first time period, surplus power obtained by subtracting power used by other devices from the supplied power is used to heat hot water in the hot water storage tank, The control unit is capable of selecting a heating capacity from a plurality of different heating capacities in the second boiling operation, and is equipped with a surplus power boiling mode in which, according to the magnitude of the surplus power, a heating capacity from the plurality of heating capacities that generates the largest total amount of boiling heat in the second time period is selected, When operating in the surplus power boiling mode, the control unit changes the heating capacity during the first time period to a heating capacity greater than the first heating capacity, and performs the first boiling operation.

3. The heat pump hot water supply device according to claim 1 , wherein when the total amount of power consumption used for the water heating operation in the second time period is the same for a plurality of heating capacities, the lowest heating capacity is selected.

4. The heat pump hot water heater according to claim 2 , wherein when a total amount of heat generated in the second time period is the same for a plurality of heating capacities, the lowest heating capacity is selected.

5. The heat pump hot water heater according to any one of claims 1 to 4, wherein a user can select whether to operate in the surplus power heating mode using an external device such as a remote control or a mobile terminal.

6. 5. The heat pump water heater according to claim 1, wherein the control unit controls the first heating operation so that the end time of the heating operation in the first time period is the same regardless of the heating capacity.

7. A heat pump water heater as described in any one of claims 1 to 4, wherein the target amount of hot water to be heated during the first time period is changed before the start of the heating operation depending on whether operation in the surplus power heating mode will be performed during the daytime the next day, and when heating in the surplus power heating mode is performed, the new target amount of hot water to be heated is set to a third amount of hot water to be heated, which is the first target amount of hot water to be heated, which is the target amount of hot water to be heated when heating in the surplus power heating mode is not performed, minus the second target amount of hot water expected to be generated during the second time period.

8. A heat pump water heater as described in any one of claims 1 to 4, wherein when operation in the surplus power heating mode is being performed during the second time period, or when operation in the surplus power heating mode is scheduled during the second time period, this fact is displayed on an external device such as a remote control or a mobile terminal to notify the user.

9. A heat pump water heater as described in any one of claims 1 to 4, wherein if operation in the surplus power heating mode during the second time period is possible, this is displayed on an external device such as a remote control or a mobile terminal, and the user is allowed to choose whether or not to operate it.

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