Storage tank type hot water supply device

Abstract

To surely execute a boiling-up operation even when hot water / water is hardly sucked to a circulation pump by cavitation.SOLUTION: An error determination portion 410G detects occurrence of a prescribed error event which may occur by insufficient circulation of hot water / water in a heating circulation circuit 4 in starting a boiling-up operation. A state determination portion 410H determines whether the prescribed state which may cause cavitation of hot water / water exists at that timing or not, in starting the boiling-up operation. In a case when the occurrence of the prescribed error event is detected, and the prescribed state is determined, a heating control device 50 increases a rotation frequency of a heating circulation pump 19 by a driving motor 19m to be higher than an ordinary rotation frequency in an ordinary boiling-up operation. Thereby, sucking action of hot water to the heating circulation pump 19 can be enhanced by the increase of the rotation frequency, and the boiling-up operation can be surely executed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a storage type hot water supply device that supplies hot water to a hot water storage tank. [Background technology]

[0002] Conventionally, this type of hot water storage type hot water supply device has been provided with an antifreeze faucet to drain hot water from the water supply pipe and hot water supply pipe connected to the hot water storage tank to prevent freezing, as described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5275172 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional system, for example, if the antifreeze faucet is left in use at night to prevent freezing and automatic boiling operation is performed in the morning, the water is drained, so there is no water supply pressure in the hot water storage tank, and if the hot water temperature is high, it becomes difficult to dissolve air in the water, which can cause cavitation.When cavitation occurs, it becomes difficult to draw hot water into the circulation pump installed in the hot water circulation circuit to the hot water storage tank, making boiling operation difficult. [Means for solving the problem]

[0005] In order to solve the above problem, claim 1 of the present invention provides a hot water circulation circuit including a hot water storage tank for storing hot water, heating means for heating a refrigerant, a heat exchanger for exchanging heat between the refrigerant heated by the heating means and the hot water in the hot water storage tank, a supply pipe from the bottom of the hot water storage tank to the heat exchanger, and a return pipe from the heat exchanger to the top of the hot water storage tank, a circulation pump for circulating the hot water in the hot water circulation circuit, pump drive means for driving the circulation pump, and a hot water circulation system in which the hot water is introduced into the heat exchanger via the supply pipe and heated by heat exchange with the refrigerant by controlling the heating means and the pump drive means and driving the circulation pump at a predetermined normal rotation speed while heating by the heating means. A hot water storage type water heater having a control means for performing a boiling operation in which the hot water is supplied to the hot water storage tank through the return pipe, an error detection means for detecting the occurrence of a specified error event that may occur due to a failure of the hot water circulation in the hot water circulation circuit at the start of the boiling operation, and a state determination means for determining whether a specified state in which cavitation of the hot water may occur is reached at the start of the boiling operation, and when the error detection means detects the occurrence of the specified error event and the state determination means determines that the specified state is reached, the control means performs the boiling operation while driving the circulation pump at an increased rotation speed higher than the normal rotation speed.

[0006] In addition, in claim 2, when the error detection means detects the specified error event at the start of the boiling operation, the control means executes a retry process to terminate the boiling operation and then resume the boiling operation, and an error confirmation process to confirm the occurrence of the specified error event when the number of times the retry process is executed reaches a predetermined threshold, and when the error detection means detects the occurrence of the specified error event but the error confirmation process does not confirm the specified error event, and the state determination means determines that the specified state has been reached, the control means executes the boiling operation while driving the circulation pump at the increased rotation speed.

[0007] In addition, in claim 3, the control means further executes a standby process in which, after the boiling operation is terminated due to the detection of the specified error event, a specified standby time is set before the boiling operation is resumed by the retry process.

[0008] In claim 4, the predetermined state includes the actual time being in a specific time zone in the morning. [Effects of the Invention]

[0009] According to claim 1 of this invention, an error detection means and a state determination means are provided to address the occurrence of cavitation after the start of boiling operation due to the use of an antifreeze faucet, as described above. The error detection means detects the occurrence of a predetermined error event that may occur due to a failure of the hot water circulation circuit at the start of boiling operation. Examples of the predetermined error event include an abnormal overcurrent flowing through the motor driving the compressor of a heat pump-type heating means, an abnormally high boiling temperature detected downstream of the heat exchanger in the hot water circulation circuit, and an empty-heat state in which the circulation pump is rotating at a speed abnormally higher than the rotation speed command value. Meanwhile, the state determination means determines whether a predetermined state in which hot water cavitation may occur is present at the start of boiling operation. An example of the predetermined state is when the outside air temperature is below a predetermined value, a predetermined time condition is satisfied, and the hot water temperature in the hot water storage tank or the hot water circulation circuit is above a predetermined value. When the occurrence of the above-mentioned predetermined error event is detected and the state determination means determines that the predetermined state has been reached, it is presumed that the occurrence of the above-mentioned predetermined error event is due to the occurrence of cavitation resulting from the use of the antifreeze faucet. As a result, the control means increases the rotation speed of the circulation pump driven by the pump drive means to a higher rotation speed than the normal rotation speed during normal boiling operation. Even when cavitation makes it difficult for hot water to be drawn into the circulation pump, this increase in rotation speed strengthens the hot water drawing action into the circulation pump, ensuring reliable boiling operation.

[0010] According to claim 2, when a predetermined error event is detected, the retry process of terminating boiling operation and then restarting boiling operation is repeated until a predetermined threshold is reached. By increasing the rotation speed of the circulation pump immediately after detecting the occurrence of the predetermined error event and repeatedly attempting to terminate and restart boiling operation, it is possible to ensure that hot water is drawn into the circulation pump, and boiling operation can be performed more reliably. In this way, all possible measures can be taken to ensure the execution of boiling operation.

[0011] Furthermore, according to claim 3, during the retry process, the flow is as follows: end of boiling operation → wait for a predetermined time → resume boiling operation. By providing a predetermined waiting time between ending and resuming boiling operation, the effects of cavitation can be reduced and the success rate of boiling operation by retry process can be increased.

[0012] Furthermore, according to claim 4, for example, if an antifreeze faucet is used at night to prevent freezing, and boiling operation is performed in the morning while the faucet is in that state, the water drainage state caused by the use of the antifreeze faucet will prevent water supply pressure from being applied to the hot water storage tank, increasing the risk of cavitation. Therefore, by including the start of boiling operation in a specific time period in the morning as a condition for determining a predetermined state in which hot water cavitation may occur, boiling operation can be reliably performed in preparation for the user's use of hot water in the morning while the antifreeze faucet is in use. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram of an entire configuration of a hot water storage type hot water heater according to an embodiment of the present invention; [Figure 2] Functional block diagram showing the functional configuration of the heating control device [Figure 3] Side view showing the installation height of the heat pump unit and hot water tank [Figure 4] A flowchart showing a control procedure executed by the heating control device. [Figure 5] Overall schematic diagram of a storage-type hot water supply system during boiling operation [Figure 6]An explanatory diagram showing the number of retry errors until the error is confirmed [Figure 7] Overall schematic diagram of the storage type hot water heater during air bleeding and anti-freeze operation DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, an embodiment of the present invention will be described with reference to the drawings.

[0015] <Schematic circuit configuration> As shown in FIG. 1, a hot water storage type water heater 100 according to this embodiment includes a tank unit 1 having a hot water storage tank 2 for storing hot water, and a heat pump unit 3.

[0016] The heat pump unit 3 includes a water-refrigerant heat exchanger 15 (corresponding to a heat exchanger) and a heating circulation pump 19 (corresponding to a circulation pump) for heating the hot water in the hot water storage tank 2. The water-refrigerant heat exchanger 15 has a refrigerant-side flow path 15b through which the refrigerant flows and a water-side flow path 15a, and exchanges heat between the high-temperature, high-pressure refrigerant and the hot water in the hot water storage tank 2. That is, the water-side flow path 15a of the water-refrigerant heat exchanger 15 and the hot water storage tank 2 are connected in a ring shape by a heating supply pipe 5 (corresponding to a supply pipe) that runs from the bottom of the hot water storage tank 2 to the water-refrigerant heat exchanger 15, and a heating return pipe 6 (corresponding to a return pipe) that runs from the water-refrigerant heat exchanger 15 back to the top of the hot water storage tank 2, forming a heating circulation circuit 4 as a hot water circulation circuit spanning the tank unit 1 and the heat pump unit 3.

[0017] The heating supply pipe 5 is connected to the bottom of the hot water storage tank 2, and the heating return pipe 6 is connected to the top of the hot water storage tank 2. The heating circulation pump 19 is provided midway along the heating supply pipe 5 and circulates the hot water from the hot water storage tank 2 within the heating circulation circuit 4 while circulating the hot water from the heating supply pipe 5 to the heating return pipe 6 via the water-side flow path 15a. The heating circulation pump 19 is driven by a drive motor 19m (corresponding to a pump driving means). The heating supply pipe 5 is provided with an inlet water temperature sensor 23 that detects an inlet water temperature T1 of the hot water flowing into the water-side flow path 15a of the water-refrigerant heat exchanger 15, and the heating return pipe 6 is provided with a boiling temperature sensor 24 (corresponding to an error detection means) that detects a boiling temperature Tb of the hot water flowing out from the water-side flow path 15a toward the hot water storage tank 2.

[0018] In the tank unit 1, a plurality of hot water temperature sensors 12 are provided vertically on the side of the hot water storage tank 2 to detect the temperature Tw of the hot water in the hot water storage tank 2. A water supply pipe 7 that supplies water to the hot water storage tank 2 is connected to the bottom of the hot water storage tank 2, and a hot water outlet pipe 8 that discharges the stored high-temperature water is connected to the top of the hot water storage tank 2. A negative pressure intake valve 119 is provided on the hot water outlet pipe 8 to open and introduce air into the hot water storage tank 2 when negative pressure occurs inside the hot water storage tank 2, and a water supply bypass pipe 9 branches off from the water supply pipe 7. The negative pressure intake valve 119 also functions as an overpressure relief valve 119 that operates when the pressure inside the hot water storage tank 2 rises to a predetermined set pressure (e.g., 450 kPa) to discharge air that has accumulated in the top of the hot water storage tank 2.

[0019] Furthermore, there are provided a mixing valve 10 that mixes hot water from the hot water outlet pipe 8 with water from the water supply bypass pipe 9 to produce hot water at a set hot water supply temperature, a hot water supply pipe 108a that supplies the hot water mixed by the mixing valve 10 to the hot water supply terminal 125, and a hot water supply temperature sensor 11 that detects the hot water temperature in the hot water supply pipe 108a. A check valve 117 is provided midway in the water supply pipe 7, which reduces the city water pressure to a certain water supply pressure (for example, a set pressure value of 380 kPa) and prevents the hot water in the hot water storage tank 2 from flowing back upstream.

[0020] A hot water supply pipe 108b is provided on the hot water supply terminal 125 side of the hot water supply pipe 108a outside the tank unit 1, and a gas heat source device 130 capable of heating the hot water mixed in the mixing valve 10 is provided between these hot water supply pipes 108a and 108b. An antifreeze faucet 120 is buried underground below the freezing depth in the primary side pipe 121 of the check valve 117 outside the tank unit 1 and in the branch pipe 123 branching off from the hot water supply pipe 108b. The antifreeze faucet 120 is provided with an operating handle 120a, a drain outlet 120b, and a hot water discharge outlet 120c.

[0021] The heat pump unit 3 also includes a compressor 14 that compresses the refrigerant, a four-way valve 31, an electronic expansion valve 16 as a pressure reducer that reduces the pressure of the refrigerant after passing through the water-refrigerant heat exchanger 15, an air heat exchanger 17 as a heat source side heat exchanger that exchanges heat between the refrigerant and air that serves as a heat source, and an outdoor fan 67 that sends outside air to the air heat exchanger 17. The compressor 14, the four-way valve 31, a refrigerant-side flow path 15b of the water-refrigerant heat exchanger 15 through which the refrigerant discharged from the compressor 14 flows, the electronic expansion valve 16, and the air heat exchanger 17 are connected in a circular manner by refrigerant piping 18, thereby forming a refrigerant circulation circuit 30.

[0022] The four-way valve 31 is a valve with four ports, and switches which of the two ports for the remaining pipe sections 18a and 18c is connected to each of the two ports for the pipe sections 18b and 18d (which constitute the main refrigerant path) of the refrigerant pipe 18. The two ports for the pipe sections 18a and 18c are connected to each other by a secondary refrigerant path made up of the pipe sections 18a and 18c arranged in a loop, and the compressor 14 is provided on this secondary refrigerant path. The compressor 14 is driven by a drive motor 14m.

[0023] 1, the four-way valve 31 connects the piping 18a on the discharge side of the compressor 14 to the piping 18b on the inlet side of the water-refrigerant heat exchanger 15, causing the air heat exchanger 17 to function as an evaporator that evaporates the low-temperature, low-pressure refrigerant from the electronic expansion valve 16. The refrigerant in the refrigerant piping 18 is then released in the water-refrigerant heat exchanger 15 to generate hot water in the heating circuit 4. The generated hot water is supplied to the hot water storage tank 2 via the heating return pipe 6 by the flow of hot water in the heating circuit 4 induced by the heating circulation pump 19, thereby raising the temperature of the hot water in the hot water storage tank 2 (boiling operation). Alternatively, when the four-way valve 31 is switched to another state, the piping 18a connects to the piping 18d on the air heat exchanger 17 side, causing the air heat exchanger 17 to function as a condenser and melting frost formed on the air heat exchanger 17 (defrosting operation). The refrigerant circulation circuit 30 and the compressor 14, four-way valve 31, air heat exchanger 17, and electronic expansion valve 16 connected thereto correspond to the heating means.

[0024] A heat pump cycle is formed by circulating, for example, an R32 refrigerant in the refrigerant circulation circuit 30. A discharge temperature sensor 20 for detecting a refrigerant discharge temperature Tout of the refrigerant discharged from the compressor 14 is provided in the refrigerant pipe 18 between the compressor 14 and the refrigerant-side flow path 15b of the water-refrigerant heat exchanger 15, and an outside air temperature sensor 22 for detecting an outside air temperature Tair is provided on the air inlet side of the air heat exchanger 17.

[0025] The tank unit 1 is provided with a hot water storage control device 40 to which the detection results of the sensors 11 and 12 are input. Similarly, the heat pump unit 3 is provided with a heating control device 50 (corresponding to a control means) to which the detection results of the sensors 20, 22, 23, and 24 are input. The heating control device 50 and the hot water storage control device 40 are connected to each other so that they can communicate with each other, and control the operation of each device in the tank unit 1 and the heat pump unit 3 while cooperating with each other based on the detection results of the sensors 11, 12, 20, 22, 23, and 24, etc.

[0026] For example, the heating control device 50 controls the drive motor 19m of the heating circulation pump 19, the compressor 14, the four-way valve 31, the outdoor fan 67, the electronic expansion valve 16, etc., and performs heating using the heat pump unit 3 while driving the heating circulation pump 19 at a predetermined normal rotation speed (e.g., 3000 rpm), thereby performing a boiling operation in which hot water is introduced into the water-refrigerant heat exchanger 15 via the heating supply pipe 5 and heated by heat exchange with the refrigerant, and then supplied to the hot water storage tank 2 via the heating return pipe 6.

[0027] It is also possible that there is a master-slave relationship in terms of control between the heating control device 50 and the hot water storage control device 40, and that, for example, the hot water storage control device 40 outputs an operation command based on the detection results of sensors 11 and 12 to the heating control device 50, and the heating control device 50 controls the operation of each device in the heat pump unit 3 based on this operation command and the detection results of each sensor 20, 22, 23, and 24. The following description of this specification will take such a case as an example.

[0028] <Heating control device> Next, we will explain the heating control device 50 provided in the heat pump unit 3. Although detailed illustrations are omitted, the heating control device 50 includes a storage unit that stores various data and programs, and a control unit that performs calculation and control processing. The functional configuration of this heating control device 50 will be explained with reference to Figure 2.

[0029] As shown in FIG. 2, the heating control device 50 functionally includes a four-way valve control unit 410A, a compressor control unit 410B, an expansion valve control unit 410C, an outdoor fan control unit 410D, a pump control unit 410F, an error determination unit 410G, and a state determination unit 410H.

[0030] The heat pump unit 3 of this embodiment performs various controls based on an operation command output from the hot water storage control device 40. That is, the operation command output by the hot water storage control device 40 is input to the four-way valve control unit 410A. In response to the operation command, the four-way valve control unit 410A determines whether the heat pump unit 3 actually causes the air heat exchanger 17 to function as an evaporator or a condenser. The four-way valve control unit 410A outputs an open / close signal corresponding to the operation mode indicated by the operation command to the four-way valve 31, thereby switching the four-way valve 31.

[0031] Furthermore, the four-way valve control unit 410A outputs operation information corresponding to the determination result to the compressor control unit 410B, the expansion valve control unit 410C, the outdoor fan control unit 410D, and the pump control unit 410F. Note that this operation information includes the temperature Tw of the hot water in the hot water storage tank 2 detected by the hot water temperature sensor 12, an appropriately determined target boiling temperature Tbo, and the like.

[0032] In this example, the compressor control unit 410B receives the outside air temperature Tair detected by the outside air temperature sensor 22, the boiling temperature Tb detected by the boiling temperature sensor 24, and the operation information corresponding to the operation command of the hot water storage control device 40 (this may be input directly or indirectly; the same applies below). In this example, the compressor control unit 410B sets a target rotation speed for the compressor 14 based on the input outside air temperature Tair and boiling temperature Tb, and controls the rotation speed of the drive motor 14m of the compressor 14 to increase or decrease so as to achieve this target rotation speed. The compressor control unit 410B also includes a current detection unit 410Ba (corresponding to error detection means). The current detection unit 410Ba detects the current value of the drive motor 14m. The current detection unit 410Ba is configured, for example, by a shunt resistor or the like provided in the power supply circuit to the drive motor 14m.

[0033] The expansion valve control unit 410C receives the refrigerant discharge temperature Tout detected by the discharge temperature sensor 20 and the operation information corresponding to the operation command of the hot water storage control device 40. In this example, the expansion valve control unit 410C controls the opening degree of the electronic expansion valve 16 to increase or decrease so that the refrigerant discharge temperature Tout becomes a desired target temperature for control.

[0034] The outdoor fan control unit 410D receives as input the outdoor air temperature Tair detected by the outdoor air temperature sensor 22 and the operation information corresponding to the operation command of the hot water storage control device 40. In this example, the outdoor fan control unit 410D sets a target rotation speed of the outdoor fan 67 based on the input operation information and the outdoor air temperature Tair, and controls the rotation speed of the outdoor fan 67 to increase or decrease so as to reach the target rotation speed.

[0035] The pump control unit 410F receives the boiling temperature Tb detected by the boiling temperature sensor 24, the outside air temperature Tair detected by the outside air temperature sensor 22, the inlet water temperature T1 detected by the inlet water temperature sensor 23, and the operation information corresponding to the operation command from the hot water storage control device 40. Based on these, the pump control unit 410F sets a target rotation speed for the drive motor 19m of the heating circulation pump 19 and controls the rotation speed of the drive motor 19m to increase or decrease so as to achieve this target rotation speed. The pump control unit 410F also includes a target rotation speed setting unit 410Fa, a drive signal output unit 410Fb, a frequency setting unit 410Fc, and a rotation speed detection unit 410Fd (corresponding to an error detection means). The rotation speed detection unit 410Fd detects the actual rotation speed of the drive motor 19m of the heating circulation pump 19. The target rotation speed setting section 410Fa, the drive signal output section 410Fb, and the frequency setting section 410Fc will be described in detail later.

[0036] The error determination unit 410G (corresponding to the error confirmation means) determines whether a predetermined error event (also referred to as a "retry error" in this specification as appropriate) that may occur due to insufficient circulation of hot water within the heating circulation circuit 4, or other error event that may occur due to failure of the various motors or sensors themselves, has occurred. The state determination unit 410H (corresponding to the state determination means) determines whether a predetermined state has occurred in which air may be trapped in the heating circulation pump 19 due to cavitation of hot water within the heating circulation circuit 4. Details of these will be described later. Determination information corresponding to the determination results by the error determination unit 410G and the state determination unit 410H is output to the four-way valve control unit 410A, compressor control unit 410B, expansion valve control unit 410C, outdoor fan control unit 410D, and pump control unit 410F.

[0037] <Background and Features of the Embodiment> As described above, in this embodiment, the antifreeze water valve 120 is provided to drain the hot water in the primary-side piping 121 and the hot water supply pipe 108b connected to the primary side of the hot water storage tank 2, thereby preventing freezing. In this configuration, for example, if the water boiling operation is performed in the morning while the antifreeze water valve 120 is in use to prevent freezing overnight, the water supply pressure in the hot water storage tank 2 is not applied due to the draining of the primary-side piping 121 caused by the use of the antifreeze water valve 120. This makes it difficult to dissolve air in the water when the hot water temperature is high, which may result in cavitation. In particular, the heating supply pipe 5 becomes negative pressure when the heating circulation pump 19 is driven, making cavitation more likely to occur. If cavitation occurs in the hot water, air may accumulate in the heating circulation pump 19, preventing the heating circulation pump 19 in the heating circulation circuit 4 to the hot water storage tank 2 from drawing in the hot water (i.e., air entrapment), which may make the boiling operation difficult.

[0038] Air entrapment is particularly likely to occur in the following cases. For example, when the hot water storage type hot water heater 100 is used in cold regions, as shown in FIG. 3, the heat pump unit 3 may be installed on a stand 60 to prevent it from being buried in snow, and the installation height may be increased by H (for example, about 1 m). Also, depending on the type of heat pump unit 3, the heating circulation pump 19 may be placed above the heat pump unit 3. In such cases, the head pressure of the hot water storage tank 2 is less likely to act on the heating circulation pump 19, and therefore, when no water supply pressure is applied to the hot water storage tank 2 due to the use of an antifreeze faucet 120, air entrapment due to cavitation is more likely to occur in the heating circulation pump 19.

[0039] Furthermore, if air is trapped due to cavitation, the heating circulation pump 19 will not be able to draw in hot or cold water, and an error will automatically occur, causing the heating circulation pump 19 to stop. As a result, if the outside temperature is low, the heating circulation circuit 4 may freeze, potentially damaging the appliance.

[0040] The main feature of this embodiment is that, in response to the above, when the retry error that may occur due to insufficient circulation of hot water in the heating circulation circuit 4 is detected at the start of the boiling operation, and when it is determined that a predetermined state in which air entrapment may occur is reached, the boiling operation is performed while driving the heating circulation pump 19 at an increased rotation speed that is higher than the normal rotation speed. To achieve this, the control method executed by the heating control device 50 of this embodiment will be described using the flowchart of FIG. 4 and the like.

[0041] 4 starts on the assumption that all boiling operations for one day (the day before the day on which this flow is executed in the morning) have been completed. First, in S5, the four-way valve control unit 410A of the heating control device 50 determines whether or not a boiling operation command has been received from the hot water storage control device 40. Until the boiling operation command is received, the determination is not satisfied (S5: No), and the process waits in a loop. Once the boiling operation command is received, the determination is satisfied (S5: Yes), and the process proceeds to S10.

[0042] In S10, the heating control device 50 resets the value of the retry count, which is the number of times a retry error has occurred.

[0043] In S15, pump control unit 410F of heating control device 50 starts a boiling operation while driving drive motor 19m of heating circulation pump 19 at a normal rotation speed. Specifically, target rotation speed setting unit 410Fa of pump control unit 410F sets target rotation speed N of heating circulation pump 19 to the normal rotation speed. As an example of the normal rotation speed, N is set to 3000 rpm. Then, drive signal output unit 410Fb generates a drive signal for rotating at target rotation speed N set by target rotation speed setting unit 410Fa and outputs the drive signal to drive motor 19m of heating circulation pump 19.

[0044] On the other hand, the four-way valve control unit 410A switches the four-way valve 31 so that the air heat exchanger 17 functions as an evaporator, the compressor control unit 410B drives the drive motor 14m of the compressor 14 and controls it to reach the target rotation speed, the expansion valve control unit 410C controls the opening of the electronic expansion valve 16 so that the refrigerant discharge temperature Tout reaches the desired target temperature for control, and the outdoor fan control unit 410D drives the outdoor fan 67 and controls it to reach the target rotation speed.

[0045] 5, in the heating circuit 4, hot water is circulated through the water-refrigerant heat exchanger 15, the heating return pipe 6, the hot water storage tank 2, the heating supply pipe 5, the water-refrigerant heat exchanger 15, and so on. Meanwhile, in the refrigerant circuit 30, the refrigerant is circulated through the water-refrigerant heat exchanger 15, the electronic expansion valve 16, the air heat exchanger 17, the compressor 14, the water-refrigerant heat exchanger 15, and so on. As a result, in the water-refrigerant heat exchanger 15, the refrigerant in flow path 15b releases heat to the hot water in flow path 15a to generate hot water. The generated hot water is supplied to the hot water storage tank 2, thereby increasing the temperature of the hot water in the hot water storage tank 2. Then, the process proceeds to S20.

[0046] In S20, the error determination unit 410G and the state determination unit 410H acquire various parameters that serve as criteria for detecting the occurrence of a retry error that may occur due to insufficient circulation of hot water or water in the heating circulation circuit 4, and various parameters that serve as criteria for determining whether a predetermined state in which air entrapment may occur has been reached. Examples of parameters for detecting the occurrence of a retry error include the current value of the drive current supplied to the drive motor 14m of the compressor 14, the boiling temperature Tb detected by the boiling temperature sensor 24, and the actual rotation speed of the drive motor 19m of the heating circulation pump 19. The current value of the drive motor 14m is detected by a current detection unit 410Ba of the compressor control unit 410B. The actual rotation speed of the drive motor 19m is detected by a rotation speed detection unit 410Fd of the pump control unit 410F. Examples of parameters for determining a predetermined state in which air entrapment may occur include the outside air temperature Tair detected by the outside air temperature sensor 22, the hot water temperature Tw in the hot water storage tank 2 detected by the hot water storage temperature sensor 12, the inlet water temperature T1 detected by the inlet water temperature sensor 23, the time when the boiling operation command was received, etc. Then, the process proceeds to S25.

[0047] In S25, the error determination unit 410G determines whether a retry error has occurred based on the values ​​of the parameters acquired in S20. A retry error is issued when at least one of the following three abnormalities (A), (B), and (C) is detected among various detectable abnormalities.

[0048] (A) Overcurrent abnormality This is the case where the current value of the drive motor 14m of the compressor 14 detected by the current detection unit 410Ba of the compressor control unit 410B is abnormally high. For example, when the current value is equal to or greater than a predetermined threshold value (for example, 15 A), an overcurrent abnormality is detected.

[0049] (B) Boiling temperature high temperature abnormality This is the case when the boiling temperature Tb detected by the boiling temperature sensor 24 is relatively high. For example, when the boiling temperature Tb continues to be equal to or higher than a predetermined threshold value (e.g., 75°C) for a predetermined time (e.g., 3 seconds), a high boiling temperature abnormality is detected.

[0050] (C) Dry firing abnormality This is the case when the actual rotation speed of the drive motor 19m detected by the rotation speed detection unit 410Fd of the pump control unit 410F is abnormally high. For example, when the heating circulation pump 19 is driven at a duty ratio corresponding to a specific command rotation speed, if there is no water (in the case of dry heating), the load is small, so the actual rotation speed of the drive motor 19m becomes abnormally higher than the specific command rotation speed compared to when there is water. Therefore, if the difference between the actual rotation speed and the specific command rotation speed is equal to or greater than a predetermined threshold (e.g., 1000 rpm), a dry heating abnormality is detected.

[0051] If the error determination unit 410G detects at least one of the above (A), (B), and (C) abnormalities and a retry error occurs (S25: Yes), the process proceeds to S30. On the other hand, if a retry error does not occur (S25: No), the process returns to S20.

[0052] In S30, the boiling operation is stopped by the heating control device 50. Specifically, a stop signal (which may be a drive signal with a target rotation speed of 0) is generated by the drive signal output unit 410Fb of the pump control unit 410F and output to the drive motor 19m of the heating circulation pump 19, stopping the circulation of hot water within the heating circulation circuit 4. In addition, the compressor control unit 410B stops the compressor 14, and the outdoor fan control unit 410D stops the outdoor fan 67. This stops the circulation of the refrigerant within the refrigerant circulation circuit 30.

[0053] In S35, the state determination unit 410H determines whether or not a predetermined state in which air entrapment may occur is reached based on the values ​​of the parameters acquired in S20. The predetermined state refers to a case in which all of the following three conditions (D), (E), and (F) are satisfied.

[0054] (D) Outside temperature conditions The outside air temperature Tair is low. Specifically, the condition is, for example, Tair<−10° C.

[0055] (E) Hot water temperature conditions The hot water temperature Tw or the inlet water temperature T1 detected by the inlet water temperature sensor 23 as the temperature of the hot water in the hot water storage tank 2 is relatively high. Specifically, the condition is, for example, Tw≧25[°C] or T1≧25[°C].

[0056] (F) Time Conditions The condition is that the time (actual time) when the boiling operation command is received is within a specific time period in the morning (for example, from the predicted boiling start time to 7:00). The predicted boiling start time is, for example, the morning boiling start time predicted by the hot water storage control device 40 or the heating control device 50 based on learning from past user usage records.

[0057] If the state determination unit 410H determines that the predetermined state is satisfied, that is, all three of the conditions (D), (E), and (F) are satisfied (S35: Yes), the process proceeds to S40. On the other hand, if the predetermined state is not satisfied (at least one of the conditions (D), (E), and (F) is not satisfied) (S35: No), the process proceeds to S70, which will be described later.

[0058] In S40, the error determination unit 410G determines whether the number of retry errors (retry count value) occurring under a predetermined condition has reached a predetermined number. The predetermined number is a threshold value that is set in advance for each type of error. For example, as shown in FIG. 6(a), if a retry error occurs due to an overcurrent abnormality, the predetermined number is set to four. As shown in FIG. 6(b), if a retry error occurs due to a high boiling temperature abnormality, the predetermined number is set to six. As shown in FIG. 6(c), if a retry error occurs due to an empty-heat abnormality, the predetermined number is set to four. If the number of retry errors has reached the predetermined number (S40: Yes), the process proceeds to S45. On the other hand, if the number of retry errors has not reached the predetermined number (S40: No), the process proceeds to S60, which will be described later. It should be noted that a retry error may occur even when the specified state is not met. In this case, if the number of retry errors reaches a specified number, operation is locked out until a specified operation is performed to ensure safety (see S70, S75, and S80 described below).

[0059] In S45, the error determination unit 410G determines whether a retry error has occurred under a predetermined condition. Specifically, as shown in FIG. 6(a), if a retry error occurs due to an overcurrent abnormality, the error is determined when the retry error has occurred four times. Also, as shown in FIG. 6(b), if a retry error occurs due to a high boiling temperature abnormality, the error is determined when the retry error has occurred six times. Also, as shown in FIG. 6(c), if a retry error occurs due to an empty-heating abnormality, the error is determined when the retry error has occurred four times. Then, the process proceeds to S50. Note that S45 corresponds to an error determination process that determines the occurrence of a predetermined error event when the number of retry processes reaches a predetermined threshold. Furthermore, the error determination unit 410G that executes S45 corresponds to an error determination means that determines the occurrence of a predetermined error event that may occur due to insufficient hot water circulation in the hot water circulation circuit after the start of boiling operation.

[0060] In S47, the heating control device 50 stops the boiling operation and waits for a predetermined waiting time T. As an example, T is set to 15 min. Note that S47 corresponds to a waiting process that sets a predetermined waiting time after the boiling operation is finished.

[0061] In S50, the heating control device 50 executes an air purging operation (corresponding to an air purging operation) to remove air from the hot water in the heating circulation circuit 4. In the air purging operation, while heating is not being performed by the heat pump unit 3, the heating circulation pump 19 is driven at a predetermined rotation speed (corresponding to a first rotation speed) under predetermined time conditions (corresponding to a first time condition) to circulate the hot water in the heating circulation circuit 4, thereby removing air from the hot water in the heating circulation circuit 4.

[0062] The predetermined time condition is set by the frequency setting unit 410Fc to, for example, 30 minutes continuously or without a time limit, and the rotation speed is set by the target rotation speed setting unit 410Fa to, for example, 5500 [rpm].

[0063] Then, drive signal output unit 410Fb generates a drive signal for rotating at target rotation speed N set by target rotation speed setting unit 410Fa under the predetermined time conditions set by frequency setting unit 410Fc, and outputs the drive signal to drive motor 19m of heating circulation pump 19. As a result, as shown in FIG. 7 , heating circulation pump 19 is driven in the manner described above, causing hot water to pass through water-refrigerant heat exchanger 15 → heating return pipe 6 → hot water storage tank 2 → heating supply pipe 5 → water-refrigerant heat exchanger 15 → ..., circulating hot water within heating circulation circuit 4. This circulation of hot water occurs when compressor 14 of heat pump unit 3 is not operating and refrigerant is not circulating within refrigerant circulation circuit 30, i.e., when no heating is performed from the refrigerant side. This allows air to be removed from heating circulation circuit 4 solely by circulating hot water. Then, the process proceeds to S55.

[0064] Note that removing air from within the heating circulation circuit 4 by the above-mentioned air venting operation refers to accumulating air in the upper part of the hot water storage tank 2. That is, during the air venting operation, the air in the heating circulation circuit 4 can be sent to the hot water storage tank 2 by operating the above-mentioned heating circulation pump 19 at high speed. At that time, the sent air remains in the upper part of the hot water storage tank 2 and is not sucked back into the heating circulation pump 19. The air that has accumulated in the upper part of the hot water storage tank 2 by the air venting operation in this way is eventually discharged from the overpressure relief valve 119 when the overpressure relief valve 119 is activated by a pressure increase caused by a temperature increase in the hot water storage tank 2 during boiling operation, or from the hot water outlet pipe 8 when hot water is supplied.

[0065] In S55, the heating control device 50 drives the heating circulation pump 19 while heating by the heat pump unit 3 is prohibited, thereby performing anti-freeze operation to circulate hot water within the heating circulation circuit 4 and prevent freezing of the heating circulation circuit 4. In the anti-freeze operation, the heating circulation pump 19 is driven under predetermined time conditions (corresponding to second time conditions) that are less frequent than the time conditions of the air bleeding operation, at a rotation speed (corresponding to a second rotation speed) that is lower than the rotation speed in the air bleeding operation and higher than the normal rotation speed, thereby circulating hot water within the heating circulation circuit 4, thereby preventing freezing of the heating circulation circuit 4.

[0066] The predetermined time condition is, for example, set by the frequency setting unit 410Fc as follows: when the heating circulation pump 19 alternately deactivates and activates, the ratio of the deactivation time ts to the activation time td is ts = 9 minutes, td = 1 minute, i.e., ts:td = 9:1. In other words, in this case, the heating circulation pump 19 repeats a cycle of 9 minutes deactivation + 1 minute activation (activation for only 1 minute out of 10 minutes). The rotation speed is set by the target rotation speed setting unit 410Fa to, for example, 4500 rpm. The initial deactivation time ts in the freeze prevention operation may be a standby process in which a predetermined standby time is set after the boiling operation is completed. In this case, step S47 may be unnecessary.

[0067] Then, drive signal output unit 410Fb generates a drive signal for rotating at target rotation speed N set by target rotation speed setting unit 410Fa under the predetermined time conditions set by frequency setting unit 410Fc, and outputs the drive signal to drive motor 19m of heating circulation pump 19. As a result, as shown in Fig. 7, heating circulation pump 19 is driven in the above-described manner, and hot water is circulated within heating circulation circuit 4 while passing through water-refrigerant heat exchanger 15 → heating return pipe 6 → hot water storage tank 2 → heating supply pipe 5 → water-refrigerant heat exchanger 15 → ... in this order. This circulation of hot water is performed when compressor 14 of heat pump unit 3 is not operating and refrigerant is not circulating within refrigerant circulation circuit 30, i.e., when heating from the refrigerant side is not performed, thereby preventing freezing within heating circulation circuit 4 by circulating hot water only.

[0068] The freeze prevention operation is stopped, for example, when a predetermined operation period (for example, 6 hours) has elapsed, when a predetermined operation end time (for example, 5:30) has arrived, or when the start time of the first automatic boiling operation of the scheduled boiling operation on the day (the day on which this flow is executed in the morning) approaches. After that, the process returns to S5.

[0069] In S60, the heating control device 50 stops the boiling operation and waits for a predetermined waiting time T. As an example, T is set to 15 min. Note that S60 corresponds to a waiting process that provides a predetermined waiting time before restarting the boiling operation by retry processing after the boiling operation has ended due to the detection of a predetermined error event.

[0070] In S65, the pump control unit 410F of the heating control device 50 restarts the boiling operation while driving the drive motor 19m of the heating circulation pump 19 at an increased rotation speed that is higher than the normal rotation speed. Specifically, the target rotation speed setting unit 410Fa of the pump control unit 410F sets the target rotation speed N of the heating circulation pump 19 to an increased rotation speed that is higher than the normal rotation speed. As an example, N is set to 5000 rpm. Then, the drive signal output unit 410Fb generates a drive signal for rotating the heating circulation pump 19 at the target rotation speed N set by the target rotation speed setting unit 410Fa and outputs the drive signal to the drive motor 19m of the heating circulation pump 19. Meanwhile, the compressor control unit 410B restarts driving the compressor 14, the expansion valve control unit 410C restarts controlling the aperture of the electronic expansion valve 16, and the outdoor fan control unit 410D restarts driving the outdoor fan 67. As a result, the boiling operation is restarted (retried) while driving the heating circulation pump 19 at an increased rotation speed. After that, the process proceeds to S90, which will be described later. Note that, if a predetermined error event is detected by the error detection means at the start of the boiling operation, this S65 corresponds to a retry process in which the boiling operation is terminated and then restarted.

[0071] In S70, the error determination unit 410G determines whether the number of retry errors occurring in a non-predetermined state (retry count value) has reached a predetermined number. The predetermined number is set in advance as a threshold value for each type of error. For example, as shown in the above-mentioned Figures 6(a), 6(b), and 6(c), it may be set to the same value as the threshold value for the number of retry errors occurring in a predetermined state. If the number of retry errors occurring has reached the predetermined number (S70: Yes), the process proceeds to S75. On the other hand, if the number of retry errors occurring has not reached the predetermined number (S70: No), the process proceeds to S85, which will be described later.

[0072] In S75, the error determination unit 410G determines that a retry error has occurred in a non-predetermined state.

[0073] In S80, operation is forcibly stopped (locked out) by the heating control device 50. Specifically, a stop signal is generated by the drive signal output unit 410Fb of the pump control unit 410F and output to the drive motor 19m of the heating circulation pump 19, stopping the circulation of hot water within the heating circulation circuit 4. Furthermore, the compressor control unit 410B stops the compressor 14, and the outdoor fan control unit 410D stops the outdoor fan 67. This stops the circulation of the refrigerant within the refrigerant circulation circuit 30.

[0074] In S85, the pump control unit 410F of the heating control device 50 restarts the boiling operation while driving the drive motor 19m of the heating circulation pump 19 at the normal rotation speed. Specifically, the target rotation speed setting unit 410Fa of the pump control unit 410F sets the target rotation speed N of the heating circulation pump 19 to the normal rotation speed. As an example, N is set to 3000 rpm. Then, the drive signal output unit 410Fb generates a drive signal for rotating the heating circulation pump 19 at the target rotation speed N set by the target rotation speed setting unit 410Fa and outputs the drive signal to the drive motor 19m of the heating circulation pump 19. Meanwhile, the compressor control unit 410B restarts driving the compressor 14, the expansion valve control unit 410C restarts controlling the aperture of the electronic expansion valve 16, and the outdoor fan control unit 410D restarts driving the outdoor fan 67. As a result, the boiling operation is restarted (retried) while driving the heating circulation pump 19 at the normal rotation speed. Then it moves to the S90.

[0075] In S90, the heating control device 50 determines whether the boiling temperature Tb detected by the boiling temperature sensor 24 has reached the target boiling temperature Tbo. If the target boiling temperature Tbo has not been reached (S90: No), the process returns to S20. On the other hand, if the target boiling temperature Tbo has been reached (S90: Yes), the process proceeds to S95.

[0076] In S95, the heating control device 50 ends the boiling operation. Specifically, the drive signal output unit 410Fb of the pump control unit 410F generates a stop signal and outputs it to the drive motor 19m of the heating circulation pump 19, stopping the circulation of hot water within the heating circulation circuit 4. Furthermore, the compressor control unit 410B stops the compressor 14, and the outdoor fan control unit 410D stops the outdoor fan 67. This stops the circulation of the refrigerant within the refrigerant circulation circuit 30. This ends the flow chart.

[0077] <Effects of the embodiment> As described above, in this embodiment, in order to deal with the occurrence of cavitation after the start of boiling operation due to the use of the antifreeze faucet 120 as described above, an error determination unit 410G and a status determination unit 410H are provided in the heating control device 50.

[0078] At the start of the boiling operation, the error determination unit 410G detects the occurrence of a retry error that can occur due to insufficient circulation of hot water within the heating circulation circuit 4. Examples of retry errors include a state in which an abnormal overcurrent flows through the drive motor 14m of the compressor 14 provided in the heat pump unit 3, a state in which the boiling temperature Tb detected downstream of the water-refrigerant heat exchanger 15 in the heating circulation circuit 4 is abnormally high, and a dry-heat state in which the heating circulation pump 19 is rotating at a rotation speed abnormally higher than the rotation speed command value.

[0079] On the other hand, the state determination unit 410H determines whether or not a predetermined state is reached at the start of the boiling operation in which cavitation of hot water can occur. An example of the predetermined state is when the outside air temperature Tair is below a predetermined value (e.g., -10°C), a predetermined time condition (e.g., a specific time period in the morning) is satisfied, and the temperature of hot water in the hot water storage tank 2 or the heating circulation circuit 4 is equal to or higher than a predetermined value (e.g., 25°C).

[0080] If the occurrence of the retry error is detected and the result of the determination by state determination unit 410H is that the predetermined state has been reached, it is presumed that the occurrence of the retry error is due to the occurrence of cavitation caused by the water being drained due to the use of antifreeze faucet 120. As a result, heating control device 50 increases the rotation speed of heating circulation pump 19 by drive motor 19m to an increased rotation speed that is higher than the normal rotation speed during normal boiling operation.

[0081] As a result, even if cavitation makes it difficult to draw hot water into the heating circulation pump 19, the increase in the rotation speed can strengthen the drawing action of hot water into the heating circulation pump 19, so that boiling operation can be performed reliably.

[0082] Furthermore, particularly in this embodiment, when a retry error is detected, the retry process of ending the boiling operation and then restarting the boiling operation is repeated up to a predetermined threshold. By increasing the rotation speed of the heating circulation pump 19 immediately after detecting the occurrence of a retry error and repeatedly attempting to end and restart the boiling operation, it is possible to ensure that hot water is drawn into the heating circulation pump 19, and the boiling operation can be performed more reliably. In this way, all possible measures can be taken to ensure the execution of the boiling operation.

[0083] In particular, in this embodiment, during retry processing, the flow is as follows: end of boiling operation → wait for a predetermined time → resume boiling operation. By providing a predetermined waiting time between ending and resuming boiling operation, the effects of cavitation can be reduced and the success rate of boiling operation through retry processing can be increased.

[0084] Furthermore, particularly in this embodiment, if the antifreeze faucet 120 is used at night to prevent freezing, and the boiling operation is performed in the morning while the antifreeze faucet 120 is still in this state, there is a greater risk of cavitation occurring because the water supply pressure is not applied to the hot water storage tank 2 due to the drainage state caused by the use of the antifreeze faucet 120. For this reason, by including the start of boiling operation as a specific time period in the morning as a condition for determining a predetermined state in which hot water cavitation may occur, boiling operation can be reliably performed in preparation for the user's use of hot water in the morning while the antifreeze faucet 120 is in use.

[0085] <Modification> The present invention is not limited to the above-described embodiments, and can be modified within the scope of the present invention.

[0086] For example, in the above embodiment, when a retry error is confirmed to have occurred in a predetermined state, the air vent operation is performed after a predetermined standby time has elapsed, and then the freeze prevention operation is performed. However, this is not limited to this. For example, when a retry error is confirmed to have occurred in a predetermined state, the freeze prevention operation may be performed after a predetermined standby time has elapsed without performing the air vent operation. In this case, due to the standby process, while the heating circulation pump 19 is stopped after the boiling operation is stopped, some head pressure from the hot water storage tank 2 acts on the inlet side of the heating circulation pump 19, causing some air to escape from the heating circulation pump 19 to the outlet side. When the heating circulation pump 19 is then driven in the freeze prevention operation, a small amount of hot water flows. As described above, the heating circulation pump 19 is repeatedly and intermittently operated during the freeze prevention operation. Therefore, cavitation may occur when the heating circulation pump 19 is subsequently driven. However, when the heating circulation pump 19 is subsequently stopped, some air from the heating circulation pump 19 escapes again to the outlet side of the heating circulation pump 19, causing a small amount of hot water to flow when the heating circulation pump 19 is driven again. By repeating this operation, hot water is circulated little by little intermittently in the heating circulation circuit 4. In this way, even if the air bleeding operation is not performed, the anti-freeze operation circulates at least the hot water in the heating circulation circuit 4, thereby preventing freezing due to low temperatures and damage to the appliances.

[0087] In the above-described modified example, the initial non-driving time ts in the freeze prevention operation may be a standby process in which a predetermined standby time is set after the boiling operation is completed. In this case, step S47 may be unnecessary.

[0088] Although not particularly provided in the above embodiment, an air vent valve may be provided in the heating circulation circuit 4 or the hot water storage tank 2.

[0089] Furthermore, for example, the heat pump cycle may be an ejector cycle using an ejector as a pressure reducer.

[0090] In the above embodiment, the heat source unit is an air-source heat pump that has an outdoor fan 67 that blows outside air while passing a refrigerant through the air heat exchanger 17 as a heat source-side heat exchanger, and exchanges heat between the outside air as a heat source and the refrigerant, but the present invention is not limited to this. That is, the heat source unit may be configured such that water or antifreeze liquid is supplied to the heat source-side heat exchanger, and the liquid exchanges heat with the refrigerant in the heat source-side heat exchanger. Alternatively, a heat source-side heat exchanger may be provided underground or in a relatively large-capacity water source, and heat may be exchanged between the underground or the water source and the refrigerant through the heat source-side heat exchanger.Furthermore, a combined heat source configuration may be provided, which includes a heat pump circuit using heat from the underground or the water source and another heat pump circuit using air heat. Furthermore, in place of the liquid, the outside air, or the water source, other substances (for example, gases including smoke, exhaust fumes, and various high-temperature gases, or fluid solids including hot sand, dust, and various particles) may be passed through the heat source side heat exchanger, as long as they are capable of exchanging heat with the refrigerant in the heat source side heat exchanger, or heat from sunlight, reflected light, or other radiation may be supplied to the heat source side heat exchanger. [Explanation of symbols]

[0091] 1 Tank Unit 2 Hot water tank 3 Heat pump unit 4 Heating circulation circuit (hot water circulation circuit) 5 Heating supply pipe (supply pipe) 6 Heating return pipe (return pipe) 12 Hot water temperature sensor 14 Compressor (heating means) 14m drive motor 15 Water refrigerant heat exchanger (heat exchanger) 16 Electronic expansion valve (heating means) 17 Air heat exchanger (heating means) 19 Heating circulation pump (circulation pump) 19m Drive motor (pump drive means) 22 Outside air temperature sensor 23 Inlet water temperature sensor 24 Boiling temperature sensor (error detection means) 30 Refrigerant circulation circuit (heating means) 31 Four-way valve (heating means) 40 Hot water storage control device 50 Heating control device (control means) 100 Storage-type hot water heater 410Ba Current detection unit (error detection means) 410F pump control unit 410Fd Rotation speed detection unit (error detection means) 410G Error determination unit (error determination means) 410H Status determination unit (status determination means) T1 Inlet water temperature Tair Outside temperature Tb boiling temperature Tout Refrigerant discharge temperature

Claims

1. A hot water storage tank for storing hot water; A heating means for heating the refrigerant; a heat exchanger for exchanging heat between the refrigerant heated by the heating means and the hot water in the hot water storage tank; A hot water circulation circuit including a forward pipe from the lower part of the hot water storage tank toward the heat exchanger and a return pipe from the heat exchanger back to the upper part of the hot water storage tank; A circulation pump that circulates the hot and cold water in the hot and cold water circulation circuit; A pump driving means for driving the circulation pump; a control means for controlling the heating means and the pump drive means, and driving the circulation pump at a predetermined normal rotation speed while heating is performed by the heating means, thereby executing a boiling operation in which the hot water introduced into the heat exchanger via the supply pipe and heated by heat exchange with the refrigerant is supplied to the hot water storage tank via the return pipe; In a hot water storage type hot water supply device having An error detection means for detecting the occurrence of a predetermined error event that may occur due to a circulation failure of the hot water in the hot water circulation circuit at the start of the boiling operation; A state determination means for determining whether or not the water is in a predetermined state in which cavitation may occur at the start of the boiling operation; having The control means When the error detection means detects the occurrence of the predetermined error event and the state determination means determines that the predetermined state has occurred, the boiling operation is performed while driving the circulation pump at an increased rotation speed higher than the normal rotation speed. A storage type hot water supply device characterized by the above.

2. The control means When the error detection means detects the predetermined error event at the start of the boiling operation, a retry process is performed to end the boiling operation and then resume the boiling operation; an error determination process for determining the occurrence of the predetermined error event when the number of times the retry process is executed reaches a predetermined threshold; Run and, When the error detection means detects the occurrence of the predetermined error event but the error determination process does not determine the occurrence of the predetermined error event, and when the state determination means determines that the predetermined state has been reached, the boiling operation is performed while driving the circulation pump at the increased rotation speed.

2. The storage type hot water supply device according to claim 1 .

3. The control means further comprises: After the boiling operation is terminated due to the detection of the predetermined error event, a standby process is executed to provide a predetermined standby time before the boiling operation is resumed by the retry process.

3. The storage type hot water supply device according to claim 2.

4. The predetermined state is Including that the actual time is a specific time period in the morning 4. The storage type hot water supply device according to claim 1, wherein the storage type hot water supply device is a storage tank type hot water supply device.

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