CN112856543A

CN112856543A - Hot water supply device

Info

Publication number: CN112856543A
Application number: CN202011093938.4A
Authority: CN
Inventors: 安川健一郎; 锅岛弘树; 立石真吾; 野村秀树; 金城贵信; 山西裕美; 长谷川良
Original assignee: Noritz Corp
Current assignee: Noritz Corp
Priority date: 2019-11-26
Filing date: 2020-10-14
Publication date: 2021-05-28
Anticipated expiration: 2040-10-14
Also published as: CN112856543B; JP2021085582A; US20210156593A1; JP7406077B2

Abstract

The invention aims to prevent high-temperature hot water from flowing out of a water faucet even if a circulation pump is in a turn-on failure. The hot water supply device includes: a first piping connected to the water inlet; a flow rate detector for detecting a flow rate of water in the first pipe; a heating mechanism for heating water; and a second pipe through which hot water flows. The second pipe is connected to the first pipe via a third pipe. The hot water supply device further includes a circulation pump disposed on a path of the first pipe and configured to send the hot water in the third pipe in a direction of the heating mechanism during operation, and a control device. The control device operates the circulation pump based on the execution command received from the real-time hot water circulation mode, and adjusts the heating temperature of the heating mechanism so that the temperature of the hot water becomes equal to or lower than the limit temperature when the setting of the hot water outflow temperature exceeds the limit temperature.

Description

Hot water supply device

Technical Field

The present disclosure relates to a hot water supply apparatus, and more particularly, to a safety function in a real-time hot water circulation mode.

Background

Some of the hot water supply devices have a so-called live hot water function of supplying hot water at an appropriate temperature immediately after the start of hot water supply even when the device is not used for a long time. The hot water supply device generally includes an inflow pipe, an outflow pipe, and a heating mechanism.

In a hot water supply device having a real-time hot water function, hot water is circulated through a pipe and a heating mechanism in the hot water supply device by a circulation pump (hereinafter, referred to as a "real-time hot water circulation mode"). The hot water supply device can supply hot water of an appropriate temperature immediately after starting to supply hot water by circulating the hot water in the device.

Depending on the country or region, a pipe connected to a hot water faucet and a pipe connected to a water faucet may be connected by a circulation pipe. In the real-time hot water circulation mode of the hot water supply device connected to the water distribution pipe having the above-described configuration, hot water circulates through the heating mechanism and the circulation pipe. Therefore, when the hot water is circulated at a high temperature, if the user twists the faucet for water, the hot water at a high temperature may flow out, which is dangerous. Therefore, a technology for improving safety in the real-time hot water circulation mode is required.

Regarding the real-time hot water circulation, for example, japanese patent laid-open No. 2007-003165 (patent document 1) discloses a real-time hot water unit "in which a temperature detector is provided between an electric heater of a return pipe and a second connection portion on an upstream side of a hot water supply pipe, and a high-temperature hot water outflow prevention member that stops operations of a circulation pump and the electric heater when a detected temperature of the temperature detector exceeds an upper limit temperature set to a temperature higher than a real-time hot water set temperature is included in a controller. (see [ abstract ])

Other examples of the real-time hot water circulation are disclosed in japanese patent laid-open publication No. 11-014142 (patent document 2).

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2007-003165

[ patent document 2] Japanese patent laid-open No. Hei 11-014142

Disclosure of Invention

[ problems to be solved by the invention ]

According to the techniques disclosed in patent documents 1 and 2, when the circulation pump fails to be turned ON (ON) in the live hot water circulation mode (a state in which the circulation pump cannot be stopped in an operating state), high-temperature hot water may flow out from the faucet for water. Therefore, there is a need for a technique that does not allow hot water of high temperature to flow out from a faucet for water even when an ON (ON) failure of a circulation pump occurs in a real-time hot water circulation mode.

The present disclosure has been made in view of the above-mentioned background, and an object of the present disclosure is to provide a technique for preventing high-temperature hot water from flowing out from a faucet for water even when an ON (ON) failure occurs in a circulation pump in a real-time hot water circulation mode.

[ means for solving problems ]

A hot water supply device according to an embodiment includes: a first piping connected to the water inlet; a flow rate detector for detecting a flow rate of water in the first pipe; a heating mechanism for heating the water flowing in from the first pipe; and a second pipe through which the hot water heated by the heating means flows. The second pipe is connected to the first pipe via an external third pipe. The hot water supply device further includes a circulation pump disposed on a path of the first pipe and configured to send the hot water in the third pipe in a direction of the heating mechanism during operation, and a control device. The control device operates the circulation pump based on the execution command received from the real-time hot water circulation mode, and adjusts the heating temperature of the heating mechanism so that the temperature of the hot water in the real-time hot water circulation mode becomes equal to or lower than the limit temperature when the setting of the hot water outflow temperature exceeds the predetermined limit temperature.

[ Effect of the invention ]

According to one embodiment, even when the ON (ON) failure of the circulation pump occurs in the real-time hot water circulation mode, the hot water at a high temperature does not flow out from the faucet for water.

The foregoing and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description, which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1 is a diagram showing an example of a hot water supply device 100 including a circulation port.

Fig. 2 is a diagram showing an example of the hot water supply apparatus 200 not including the circulation port.

Fig. 3 is a diagram showing an example of the configuration of the controller 250.

Fig. 4 is a diagram illustrating an example of an outline of the operation of the hot water supply apparatus 200 in the hot water supply mode.

Fig. 5 is a diagram showing an example of an outline of the operation of the hot water supply apparatus 200 in the real-time hot water circulation mode.

Fig. 6 is a diagram showing an example of an outline of the operation of the hot water supply apparatus 200 when the ON (ON) failure of the circulation pump 207 occurs in the real-time hot water circulation mode.

Fig. 7 is a diagram showing an example of the first operation of the hot water supply apparatus 200.

Fig. 8 is a diagram showing an example of the second operation of the hot water supply apparatus 200.

Fig. 9 is a diagram showing another example of the hot water supply apparatus 200 not including the circulation port.

[ description of reference numerals ]

100. 200: hot water supply device

101. 201: bypass servo

102. 108, 202, 901: flow detector

103. 105, 203: temperature detector

104. 204: heat exchanger

106. 206: water volume servo

107. 207: circulating pump

110: water supply pipe

111. 112, 113, 211, 213: port(s)

120. 130, 130: valve with a valve body

140: hot water supply plug

150. 250: controller

155. 160, 165, 170, 255, 260, 265, 280, 281, 282: route of travel

214. 902: valve with a valve body

301：CPU

302: memory device

303: electronic circuit

304: interface

305: bus line

306: informing device

307: remote controller

310: combustion mechanism

Detailed Description

Hereinafter, embodiments of the technical idea of the present disclosure will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. In the following description, the case where water or warm water enters a certain place is referred to as "inflow". In addition, the case where water or warm water goes out from a certain place is referred to as "outflow".

The hot water supply device generally includes a port through which tap water flows in, and a port through which heated warm water flows out. In some of the hot water supply devices, a circulation port for allowing the hot water flowing out from a port through which the heated hot water flows out to flow into the hot water supply device is provided in order to circulate the hot water in the hot water supply device in the real-time hot water circulation mode. Some hot water supply devices do not include a separate circulation port, and a port through which tap water flows also serves as a circulation port.

The control of the real-time hot water circulation mode according to the present embodiment is mainly suitably applicable to a hot water supply apparatus that does not include a separate port. First, the configuration of the hot water supply device including the port, the configuration of the hot water supply device not including the port, and the configuration of the controller controlling the hot water supply device will be described in order. Next, a method of controlling the hot water supply device according to the present embodiment will be described.

[ Structure of Hot Water supply device ]

Fig. 1 is a diagram showing an example of a hot water supply device 100 including a circulation port. The hot water supply device 100 includes a bypass servo (servo)101,

flow rate detectors

102 and 108,

temperature detectors

103 and 105, a heat exchanger 104, a water amount servo 106, a circulation pump 107,

ports

111, 112 and 113, and a controller 150.

The port 111 is connected to a water supply pipe 110 for supplying water. Water is supplied from the water supply pipe 110 to the hot water supply device 100 via the port 111. The water flows into the hot water supply device 100 by the pressure of the inlet water from the water supply pipe 110. Therefore, when the pipe in the hot water supply device 100 is filled with water or warm water, the flow of water from the water supply pipe 110 into the hot water supply device 100 is stopped. In addition, when the valve 130 is opened, the water flowing in from the water supply pipe 110 flows out from the hot water supply hydrant 140.

A part of the water flowing into the hot water supply apparatus 100 from the port 111 flows into the heat exchanger 104 through the path 155. A part of the water flowing into the hot water supply apparatus 100 from the port 111 flows out from the port 113 through the

paths

160 and 165. The path 155 is a path from the outlet of the bypass servo 101 to the inlet of the heat exchanger 104. The path 160 is a path from the exit of the bypass servo 101 to the point of merging of the paths 165. Path 165 is the path from the outlet of heat exchanger 104 to port 113.

The port 112 and the port 113 are connected to the same pipe. In the real-time hot water circulation mode, the warm water flowing out of the port 113 flows into the hot water supply apparatus 100 again from the port 112 and circulates through the heat exchanger 104.

The port 113 is connected to a pipe connected to the hot water supply plug 140. In the hot water supply mode, the hot water flowing out of the port 113 is supplied from the hot water supply plug 140 to the user. The hot water supply mode is an operation mode when the hot water heated by the heat exchanger 104 flows out from the hot water supply plug 140 (when the user uses the hot water). In the real-time hot water circulation mode, the warm water flowing out of the port 113 is circulated through the hot water supply device 100 via the port 112.

The bypass servo 101 adjusts the ratio of the amount of water flowing into the path 155 to the amount of water flowing into the path 160. For example, the bypass servo 101 has a plug using a stepping motor or the like, and the amount of water flowing into the passage 160 can be adjusted by the plug. The water flowing into the heat exchanger 104 through the path 155 becomes warm water heated by the heat exchanger 104. The water flowing into the path 160 is mixed with the warm water flowing out of the heat exchanger 104 in the path 165, and the temperature of the warm water is adjusted.

The flow rate detector 102 detects the amount of water flowing through the path 155. In an aspect, the flow detector 102 includes a water wheel or the like inside, and may detect the amount of water from the amount of rotation of the water wheel or the like. In this case, the flow rate detector 102 outputs a signal generated based on the amount of rotation of the water wheel or the like to the controller 150. The signal output to the controller 150 may be a digital signal or an analog signal. The controller 150 may presume the amount of water flowing through the path 155 based on the inputted signal and determine whether water flows through the path 155.

The temperature detector 103 detects the temperature of the water passing through the flow detector 102. As shown in fig. 1, water flowing from the water supply pipe 110 and warm water flowing through the path 170 by the circulation pump 107 flow into the flow rate detector 102. Therefore, when the hot water supply device 100 operates in the real-time hot water circulation mode, the temperature detector 103 detects the temperature of the hot water circulating through the path 155, the path 165, and the path 170. In addition, when the hot water supply device 100 is not operated in the real-time hot water circulation mode, the temperature detector 103 detects the temperature of water flowing into the hot water supply device 100 from the water supply pipe 110. The temperature detector 103 may detect the temperature of water or warm water mixed with warm water circulating through the path 155, the path 165, and the path 170, the water flowing from the water supply pipe 110 into the hot water supply device 100.

In some aspects, the temperature detector 103 may also be a thermistor (thermistor). In this case, the temperature detector 103 outputs a signal generated based on the temperature of the water passing through the flow detector 102 to the controller 150. The signal output to the controller 150 may be a digital signal or an analog signal. The controller 150 may detect the temperature of the water flowing in the path 155 based on the inputted signal.

The heat exchanger 104 (heating means) raises the temperature of the water flowing into the heat exchanger 104 using heat generated by a combustion means (not shown) or the like. In some aspects, the combustion mechanism may include a burner (burner) that generates heat by burning gas or oil, or the like. On the other hand, the heat exchanger 104 includes a tube having high thermal conductivity inside. Around the tube, a plate for transferring heat may be disposed. The combustion mechanism heats the tubes and the plates. The water is heated through the pipe to become warm water. Warm water flows out from path 165 toward port 113.

The temperature detector 105 detects the temperature of the warm water flowing in the path 165. When the valve 120 is opened, warm water via the path 165 flows out of the hot water feed spigot 140. Therefore, the temperature detector 105 can be said to directly detect the temperature of the warm water used by the user. In some aspects, the temperature detector 105 may also be a thermistor. In this case, the temperature detector 105 outputs a signal generated based on the temperature of the warm water flowing in the path 165 to the controller 150. The signal output to the controller 150 may be a digital signal or an analog signal. The controller 150 may detect the temperature of the warm water flowing in the path 165 based on the inputted signal.

The water amount servo 106 adjusts the amount of warm water flowing out from the port 113. For example, the water amount servo 106 has a plug using a stepping motor or the like, and the amount of hot water flowing out from the port 113 can be adjusted by the plug.

When the valve 120 is opened, warm water flowing out of the port 113 flows out of the hot water supply plug 140. In addition, when the valve 120 is closed and the hot water supply apparatus 100 is operated in the real-time hot water circulation mode, the hot water flowing out of the port 113 flows into the port 112.

The circulation pump 107 circulates the warm water flowing from the port 112 through the heat exchanger 104. In one aspect, the circulation pump 107 may be a pump driven by a Direct Current (DC) motor or the like. In this case, the DC motor of the circulation pump 107 may be controlled by the controller 150.

The flow rate detector 108 detects the amount of warm water flowing through the path 170. In an aspect, the flow detector 108 includes a water wheel or the like inside, and may detect the amount of water from the amount of rotation of the water wheel or the like. In this case, the flow rate detector 108 outputs a signal generated based on the amount of rotation of the water wheel or the like to the controller 150. The signal output to the controller 150 may be a digital signal or an analog signal. The controller 150 may presume the amount of warm water of the path 170 based on the inputted signal and determine whether warm water flows through the path 170.

The controller 150 controls the entire hot water supply device 100. Specifically, the controller 150 obtains signals output from the

flow rate detectors

102 and 108 to estimate the amount of water in each path, and obtains signals output from the

temperature detectors

103 and 105 to estimate the temperature of water or hot water flowing through each path. Further, the controller 150 can adjust the flow rate and temperature of the water or the hot water by controlling various actuators (the bypass servo 101, the water amount servo 106, the circulation pump 107, the heat exchanger 104, and the like). In one aspect, the controller 150 may be disposed inside the hot water supply apparatus 100 or may be disposed outside the hot water supply apparatus 100.

Next, an outline of operations in the hot water supply mode and the real-time hot water circulation mode of the hot water supply device 100 will be described. The operation of the hot water supply apparatus 100 when the circulation pump 107 fails when the hot water supply apparatus 100 is operating in the real-time hot water circulation mode will also be described.

In the hot water supply mode, the hot water supply apparatus 100 heats water flowing in from the water supply pipe 110 by the heat exchanger 104, and causes warm water to flow out from the port 113. When the valve 120 is opened, the warm water flowing out of the port 113 flows out of the hot water supply plug 140. In the hot water supply mode, the circulation pump 107 is stopped, and the hot water flowing out of the port 113 does not flow into the passage 170 or flows into the passage 170 only in a small amount.

In the real-time hot water circulation mode, the hot water supply device 100 heats water flowing in from the water supply pipe 110 by the heat exchanger 104 and causes warm water to flow out from the port 113. In the real-time hot water circulation mode, the circulation pump 107 operates to discharge the hot water flowing out of the port 113 to the path 170 side. When the valve 120 is closed, the warm water flowing out of the port 113 is discharged by the circulation pump 107 and flows into the path 170. When the warm water during circulation reaches a temperature preset by the controller 150, the circulation pump 107 is stopped. The warm water is not gradually circulated in the hot water supply device 100 based on the stop of the circulation pump 107.

In the real-time hot water circulation mode, the circulation pump 107 may have an ON (ON) failure and no longer receive control from the controller 150. When the circulation pump 107 is in the ON (ON) failure state, although the temperature of the warm water during circulation reaches the temperature preset by the controller 150, the circulation pump 107 does not stop, and thus the warm water continues to circulate.

The controller 150 stores the state of the operation mode of the hot water supply device 100 (hot water supply mode, real-time hot water circulation mode, etc.) in an internal memory, and acquires the detection result of the water amount in the path 170 from the flow rate detector 108. Therefore, in a state where the operation mode of the hot water supply apparatus 100 is not the real-time hot water circulation mode, the controller 150 may determine that the ON (ON) failure of the circulation pump 107 occurs based ON the amount of water flowing through the path 170 being equal to or greater than a predetermined threshold value. The controller 150 may notify the user of the occurrence of a failure of the circulation pump 107 using a notification device or the like. As described above, the hot water supply device 100 including the circulation port can detect the ON (ON) failure of the circulation pump 107 in the real-time hot water circulation mode.

Fig. 2 is a diagram showing an example of the hot water supply apparatus 200 not including the circulation port. The hot water supply device 200 includes a bypass servo 201, a flow rate detector 202,

temperature detectors

203 and 205, a heat exchanger 204, a water amount servo 206, a circulation pump 207,

ports

211 and 213, and a controller 250.

The bypass servo 201, the flow rate detector 202, the temperature detector 203, the temperature detector 205, the heat exchanger 204, the water amount servo 206, the circulation pump 207, the port 211, the port 213, and the controller 250 of the hot water supply apparatus 200 correspond to the bypass servo 101, the flow rate detector 102, the temperature detector 103, the temperature detector 105, the heat exchanger 104, the water amount servo 106, the circulation pump 107, the port 111, the port 113, and the controller 150 of the hot water supply apparatus 100, respectively. Each of the

paths

255, 260, and 265 corresponds to each of the

paths

155, 160, and 165.

It is understood that the hot water supply device 200 does not include a circulation port and does not include a path corresponding to the path 170, as compared to the hot water supply device 100. Instead, the hot water supply device 200 includes a circulation pump 207 on the upstream side of the bypass servo 201. The difference in the structure of the hot water supply device 100 and the hot water supply device 200 is caused by the difference in the structure of the waterway apparatus in a country, a region, or the like.

As shown in fig. 2, in a waterway facility in a certain country or region, a path 280 through which water flowing in from the water supply pipe 110 flows and a path 281 through which warm water flowing out from the hot water supply device 200 flows are connected via a path 282. A backflow prevention valve 214 is provided in the passage 282. Valve 214 is a valve to prevent water from flowing from path 280 into path 281.

It is assumed that in the waterway apparatus having the above-described configuration, warm water is circulated through the hot water supply device 200 via the port 211 and the port 213. Therefore, the hot water supply device 200 does not include a circulation port connected to a path branched from the path 281. Since the hot water supply device 200 needs to circulate the hot water through the path 281 and the path 260, the circulation pump 207 is provided on the downstream side of the port 211.

Next, an outline of the operation of the hot water supply mode and the real-time hot water circulation mode of the hot water supply device 200 will be described. A problem of the hot water supply apparatus 200 when the ON (ON) failure of the circulation pump 207 occurs in the live hot water circulation mode will be described.

In the hot water supply mode, the hot water supply device 200 heats water flowing in from the water supply pipe 110 by the heat exchanger 204 and allows warm water to flow out from the port 213. When the valve 120 is opened, the warm water flowing out of the port 213 flows out of the hot water supply plug 140. When the warm water flowing through the passage 281 flows out from the hot water supply plug 140, no water pressure is applied to the valve 214, and therefore the warm water does not flow into the passage 280 from the passage 281, or only a small amount of warm water flows into the passage 280 from the passage 281.

In the real-time hot water circulation mode, the hot water supply device 200 heats water flowing in from the water supply pipe 110 by the heat exchanger 204 and allows warm water to flow out from the port 213. In the real-time hot water circulation mode, the circulation pump 207 is operated to flow warm water from the port 211 in the direction of the path 255. As long as the valve 120 is closed, a force of flowing into the port 211 acts on the warm water flowing out from the port 213 by the circulation pump 207. Therefore, the warm water flowing out of the port 213 flows into the port 211 through the path 281, the path 282, and the path 280. As a result, the warm water circulates through the path 280, the path 255, the heat exchanger 204, the path 265, the path 281, and the path 282.

When the temperature of the warm water during circulation reaches a temperature preset by the controller 250, the circulation pump 207 is stopped. The warm water is not gradually circulated in the hot water supply device 200 based on the stop of the circulation pump 207.

When the circulation pump 207 is in the ON (ON) failure state, although the temperature of the warm water during circulation reaches the temperature preset by the controller 250, the circulation pump 207 is not stopped, and thus the warm water continues to circulate.

The hot water supply apparatus 100 can detect the ON (ON) failure of the circulation pump 107, but the hot water supply apparatus 200 cannot clearly detect the ON (ON) failure of the circulation pump 207 in terms of the apparatus structure. The reason why the hot water supply apparatus 200 cannot detect the ON (ON) failure of the circulation pump 207 is that the paths before and after the circulation pump 207 have both functions of the water inlet path in the hot water supply mode and the circulation path in the live hot water circulation mode.

As shown in fig. 2, the controller 250 needs to use the detection result of the flow rate detector 202 in order to determine whether the circulation pump 207 is malfunctioning. When the flow detector 202 does not detect the flow of water or warm water after the real-time hot water circulation mode is ended, the controller 250 may determine that the circulation pump 207 is normally stopped. However, conversely, when the flow detector 202 detects the flow of water or warm water after the real-time hot water circulation mode is ended, the controller 250 cannot determine whether the ON (ON) failure of the circulation pump 207 occurs. The reason is that: even if the circulation pump 207 is normally turned OFF (OFF), when the user opens the valve 120 to allow warm water to flow out of the hot water supply plug in the hot water supply mode, the flow rate detector 202 detects the flow of water or warm water since water flows into the hot water supply device 200 from the water supply pipe 110. In this way, the hot water supply apparatus 200 not including the circulation port cannot clearly determine whether an ON (ON) failure of the circulation pump 207 has occurred or whether only the user uses hot water, using only the detection result of the flow rate detector 202.

If the circulation pump 207 fails when the hot water supply device 200 circulates hot water in the live hot water circulation mode with a high temperature setting, the hot water having a high temperature continues to circulate through the path 280 even after the live hot water circulation mode is completed. In this state, if the user opens the valve 130, hot water having a high temperature flows out from the hot water supply plug 140, which may cause danger. Therefore, in order to avoid this, the hot water supply apparatus 200 ensures the safety of the user by a control method described later.

[ Structure of controller ]

Fig. 3 is a diagram showing an example of the configuration of the controller 250. Controller 250 includes a Central Processing Unit (CPU) 301, memory 302, electronic circuitry 303, an interface 304, and a bus 305. The controller 250 controls the hot water supply device 200 in communication with various sensors and actuators of the hot water supply device 200. In addition, the controller 250 notifies the user of information related to the hot water supply apparatus 200 by the notification device 306. Further, the controller 250 may control the hot water supply apparatus 200 based on the user's input received by the remote controller 307.

The CPU 301 executes various programs read in the memory 302, or refers to data. In some aspects, the CPU 301 may be an embedded CPU, a Field-Programmable Gate Array (FPGA), a combination thereof, or the like. The CPU 301 may execute programs to realize various functions of the hot water supply apparatus 200. For example, the CPU 301 may include an ON/OFF operation (ON/OFF) of an operation switch of the hot water supply device 200, a setting of a hot water supply temperature, various time reservation settings (also referred to as "timer settings"), and the like. The CPU 301 controls the motor, the combustion mechanism, and the like in the hot water supply apparatus 200 based on these settings.

The memory 302 stores programs executed by the CPU 301 and data referred to by the CPU 301. In some aspects, Dynamic Random Access Memory (DRAM) or Static Random Access Memory (SRAM) may also be used as Memory 302.

The electronic circuit 303 is a circuit having a dedicated function. The electronic circuit 303 may perform specific processing such as data conversion or control of an actuator instead of the CPU 301. In some aspects, the electronic Circuit 303 may include at least one Application Specific Integrated Circuit (ASIC), at least one field programmable gate array, or a combination thereof.

The interface 304 performs input/output of signals with an external device. The CPU 301 may control other devices via the interface 304. The interface 304 may be connected with at least the combustion mechanism 310, the circulation pump 207, the temperature detector 203, and the temperature detector 205 of the heat exchanger 204, the flow detector 202, the bypass servo 201, and the water amount servo 206. Further, the interface 304 may be connected to the notification device 306 and the remote controller 307.

In some aspects, interface 304 may comprise a wired interface, a wireless interface, or a combination thereof that inputs/outputs or transceives any form of signal. On the other hand, the interface 304 can transmit and receive data using a communication Protocol such as a Transmission Control Protocol/Internet Protocol (TCP/IP) or a User Datagram Protocol (UDP), among other devices, the notification device 306, the remote controller 307, and other arbitrary devices. In addition, the interface 304 may also communicate with a cloud service or the like. The bus 305 connects the CPU 301, the memory 302, the electronic circuit 303, and the interface 304 to each other.

The notification device 306 may include at least one speaker, at least one display, a communication device for at least one other device, or a combination thereof. For example, notification device 306 may notify remote controller 307 that various settings have been received or that the operation of receiving a reservation (e.g., boiling water) has ended. In addition, when an abnormality occurs in the hot water supply device 200, the notification device 306 may notify the occurrence of the abnormality.

The remote controller 307 is a controller prepared separately from the main body of the hot water supply apparatus 200, and receives inputs of various operations by a user and outputs the received inputs to the controller 250. In one aspect, the remote controller 307 may be integrated with the hot water supply apparatus 200. The operation of the hot water supply apparatus 200 described with reference to fig. 4 to 8 may be realized by controlling the hot water supply apparatus 200 by the controller 250 shown in fig. 3. The operations shown in fig. 4 to 8 ensure the safety of the user when the circulation pump 207 of the hot water supply apparatus 200 described with reference to fig. 2 has an ON (ON) failure.

[ outline of operation of the hot water supply device 200 in the Hot Water supply mode ]

Fig. 4 is a diagram illustrating an example of an outline of the operation of the hot water supply apparatus 200 in the hot water supply mode. With reference to fig. 4, how the CPU 301 controls the hot water supply apparatus 200 based on the temperature setting and the setting of the operation mode that are input from the remote controller 307 will be described.

First, the operation of the hot water supply apparatus 200 in the hot water supply mode will be described. The hot water supply mode is generally a mode in which the user uses the hot water flowing out of the hot water supply plug 140. In the case where the hot water supply apparatus 200 is operated in the hot water supply mode, when the valve 120 is opened, the warm water heated by the heat exchanger 204 flows out of the hot water supply hydrant 140. Water is supplied from the water supply pipe 110 to the hot water supply device 200 at any time while using the hot water heated by the hot water supply device 200. Arrow 400 in the figure indicates the flow of water and hot water in the hot water supply mode.

Next, the operation of the CPU 301 when the remote controller 307 receives an operation to set the temperature when the hot water supply apparatus 200 is operated in the hot water supply mode will be described. When the remote controller 307 receives an input of a high temperature setting (for example, a setting to 70 ℃) when the hot water supply apparatus 200 operates in the hot water supply mode, the CPU 301 controls the heat exchanger 204 so that the temperature of the hot water flowing out of the hot water supply apparatus 200 becomes the temperature as the received setting.

The hot water supply mode is a mode on the premise of using hot water, and it is assumed that hot water that the user understands as high temperature flows out from the hot water supply plug 140. As indicated by arrow 400, when valve 120 is opened, the warm water flowing out of port 213 does not flow into port 211. Therefore, since the possibility of the user being scalded is considered to be low, the CPU 301 controls the hot water supply device 200 so that the temperature of the hot water becomes the temperature setting received.

Next, the operation of the CPU 301 when the remote controller 307 receives an input operation in the real-time hot water circulation mode when the hot water supply apparatus 200 is operated in the hot water supply mode will be described. The CPU 301 may take two actions.

In the first operation, when receiving an input operation of the real-time hot water circulation mode, the CPU 301 determines whether or not the temperature setting of the hot water flowing out from the hot water supply apparatus 200 at present is equal to or higher than a predetermined limit temperature (Th 1). When it is determined that the temperature of the hot water flowing out of the hot water supply device 200 at present is equal to or higher than the predetermined limit temperature (Th1), the CPU 301 changes the temperature setting to the temperature of the limit temperature (Th 1). When it is determined that the temperature setting of the hot water flowing out of the hot water supply device 200 at present is less than the predetermined limit temperature (Th1), the CPU 301 does not change the temperature setting. Next, the CPU 301 shifts the hot water supply device 200 to the real-time hot water circulation mode in a state where the set temperature is equal to or lower than the limit temperature (Th 1).

The limiting temperature (Th1) here is, for example, about 48 ℃. The temperature of 48 ℃ is an example, and the example of the limit temperature (Th1) is not limited thereto. The temperature limit (Th1) may be a temperature at which the user does not scald when using the hot water flowing out of the hot water supply plug 140.

By operating the hot water supply device 200 based ON the first operation, even when the ON (ON) failure of the circulation pump 207 occurs, the user opens the valve 130 (expecting the supply of water) and warm water flows out from the hot water supply plug 140, and the temperature of the warm water is not higher than the limit temperature (Th1), so that the user is not scalded.

In one aspect, CPU 301 may return the set temperature to the original temperature in a state where flow rate detector 202 no longer detects the flow of warm water (in a state where it is confirmed that circulation pump 207 has stopped) after the real-time hot water circulation mode is ended.

In the second operation, when the input operation of the real-time hot water circulation mode is received, the CPU 301 determines whether or not the temperature setting of the hot water flowing out from the hot water supply apparatus 200 at present is equal to or higher than a predetermined limit temperature (Th 1).

When it is determined that the temperature setting of the hot water flowing out of the hot water supply device 200 at present exceeds the predetermined limit temperature (Th1), the CPU 301 does not shift the hot water supply device 200 to the real-time hot water circulation mode. When it is determined that the temperature of the hot water flowing out of the hot water supply device 200 at present is equal to or lower than a predetermined limit temperature (Th1), the CPU 301 shifts the hot water supply device 200 to the real-time hot water circulation mode. In one aspect, the CPU 301 may notify the user that the hot water supply apparatus 200 cannot be switched to the real-time hot water circulation mode from the notification apparatus 306 without switching the hot water supply apparatus 200 to the real-time hot water circulation mode.

By operating the hot water supply device 200 based on the second operation, the hot water supply device 200 does not transit to the real-time hot water circulation mode at the set temperature exceeding the limit temperature (Th 1). Therefore, even if the hot water supply apparatus 200 is in the real-time hot water circulation mode, the circulation pump 207 is turned ON (ON) in failure, and the user is not scalded.

[ outline of operation of the hot water supply apparatus 200 in the real-time hot water circulation mode ]

Fig. 5 is a diagram showing an example of an outline of the operation of the hot water supply apparatus 200 in the real-time hot water circulation mode. With reference to fig. 5, the operation at the end of the real-time hot water circulation mode in the first operation described in fig. 4 will be described.

First, the operation of the hot water supply apparatus 200 in the real-time hot water circulation mode will be described. The circulation pump 207 is operated in the real-time hot water circulation mode. In addition, the hot water supply tap 140 is not normally used by the user and the valve 120 is closed. Therefore, the warm water circulates in the hot water supply apparatus 200 in the flow direction indicated by the arrow 500.

Next, the operation of the hot water supply apparatus 200 at the end of the real-time hot water circulation mode will be described. The CPU 301 causes the hot water supply apparatus 200 to end the real-time hot water circulation mode, based on the temperature of the hot water during circulation reaching the set temperature. The CPU 301 may determine whether the temperature of the warm water during the cycle has reached the set temperature based on the detection result of the temperature detector 203 or the temperature detector 205.

The CPU 301 causes the hot water supply apparatus 200 to end the real-time hot water circulation mode in the following order. As a first step, the CPU 301 changes the operation mode of the hot water supply apparatus 200 stored in the memory 302 from the real-time hot water circulation mode to another mode (standby mode or the like). As a second step, the CPU 301 stops the circulation pump 207. As a third step, the CPU 301 periodically refers to the detection value of the flow rate detector 202 for a predetermined period until the flow rate of the hot water detected by the flow rate detector 202 becomes equal to or less than a predetermined threshold value. As a fourth step, the CPU 301 determines that the circulation pump 207 is stopped, based on the fact that the flow rate of the hot water detected by the flow rate detector 202 becomes equal to or less than a predetermined threshold value (based on the flow termination of the determined arrow 500) for a predetermined period. As a fifth step, when the set temperature input by the user is equal to or higher than the limit temperature (Th1), the CPU 301 returns the set temperature to the original temperature (returns the current set temperature to the set temperature input by the user).

Fig. 6 is a diagram showing an example of an outline of the operation of the hot water supply apparatus 200 when the ON (ON) failure of the circulation pump 207 occurs in the real-time hot water circulation mode. With reference to fig. 6, the operation at the end of the real-time hot water circulation mode when the ON (ON) failure of circulation pump 207 occurs in the first operation described in fig. 4 will be described.

The first to third steps are the same as those described with reference to fig. 5. In the fourth step, when the circulation pump 207 has an ON (ON) failure, the circulation pump 207 continues to operate, and therefore the flow rate of the hot water detected by the flow rate detector 202 does not become equal to or less than a predetermined threshold value for a predetermined period of time. If the circulation pump 207 has an ON (ON) failure, warm water flows out from the hot water supply plug 140 as indicated by an arrow 600 when the user opens the valve 120. When the warm water continues to flow even after the lapse of the certain period of time as described above, the CPU 301 determines that the circulation pump 207 has an ON (ON) failure. As a fifth step, the CPU 301 causes the notification device 306 to notify a message that the delivery circulation pump 207 has failed. The user can find an abnormality in the hot water supply device 200 by referring to the notification content from the notification device 306, and can communicate with a service person or the like.

[ operation sequence of the Hot Water supply device 200 ]

Fig. 7 is a diagram showing an example of the first operation of the hot water supply apparatus 200 in the real-time hot water circulation mode. The processing shown in fig. 7 is a processing flow of the CPU 301 when the first operation described in fig. 4 to 6 is realized. In some aspect, the CPU 301 may read a program to perform the processing of fig. 7 from the memory 302 and execute the program. On the other hand, a part or all of the processing may be realized in the form of a combination of circuit elements configured to execute the processing.

In step S705, when entering the real-time hot water circulation mode, the CPU 301 sets the set temperature of hot water supply to the limit temperature (Th1) or less. When the original set temperature (T) exceeds the limit temperature (Th1), the CPU 301 changes the set temperature from the original set temperature (T) to the limit temperature (Th 1). If not, the CPU 301 maintains the set temperature at the original set temperature (T). When the set temperature is changed to the limit temperature (Th1), the CPU 301 stores the original information of the set temperature (T) in the memory 302 for the processing of step S745.

In step S710, the CPU 301 outputs an ON (ON) instruction to the circulation pump 207. When an ON (ON) command is input from CPU 301, circulation pump 207 operates to circulate warm water. In some aspects, the turn-ON (ON) command may be a digital signal or may be an analog signal. ON the other hand, the CPU 301 may output an ON (ON) command to the electronic circuit 303, and the electronic circuit 303 to which the ON (ON) command is input directly controls the circulation pump 207.

In step S715, if it is determined that the temperature of the hot water during the cycle has reached the set temperature based on the detection results of the

temperature detectors

203 and 205, the CPU 301 changes the state of the hot water supply device 200 to the real-time hot water cycle end. In step S705, when the CPU 301 sets the set temperature to the limit temperature (Th1), the CPU 301 changes the state of the hot water supply device 200 to the real-time hot water circulation end based on the temperature of the hot water during the circulation reaching the limit temperature (Th 1).

In one aspect, the CPU 301 may store the state of the hot water supply device 200 (hot water supply standby, hot water supply in progress, real-time hot water standby, real-time hot water circulation in progress, real-time hot water circulation end, and the like) in the memory 302. In this case, the CPU 301 manages the state of the hot water supply apparatus 200 by rewriting the state of the hot water supply apparatus 200 in the memory 302.

In step S720, the CPU 301 outputs an OFF (OFF) instruction to the circulation pump 207. The circulation pump 207 is stopped when a disconnection (OFF) instruction is input from the CPU 301. If the circulation pump 207 is stopped, the warm water in the circulation process is not circulated soon. In some aspects, the OFF command may be a digital signal or an analog signal. On the other hand, CPU 301 may output an OFF command to electronic circuit 303, and electronic circuit 303 having the OFF command input thereto may stop circulation pump 207.

In step S725, the CPU 301 determines whether the counter is equal to or less than the upper limit value (N). The CPU 301 determines whether a predetermined period (count number N) has elapsed from the start of counting based on the value of the counter. The value of the counter is used to determine whether the processing of step S735 has timed out. When the determined counter is equal to or less than the upper limit value (N) (YES in step S725), the CPU 301 proceeds to step S730. If not (NO in step S725), the CPU 301 proceeds to step S750.

In step S730, the CPU 301 increments. In step S735, the CPU 301 determines whether the flow rate detector 202 no longer detects water flow. That is, the CPU 301 determines whether or not the circulation of the warm water has stopped. If it is determined that the flow rate detector 202 is no longer detecting water flow (YES in step S735), the CPU 301 proceeds to step S740. If not (NO in step S735), the CPU 301 moves control to step S725.

In step S740, the CPU 301 determines that the circulation pump 207 has normally stopped, and releases the limitation of the set temperature. In step S705, when the CPU 301 has changed the set temperature from the original set temperature (T) to the limit temperature (Th1), the CPU 301 returns the set temperature to the original set temperature (T).

In step S745, the CPU 301 controls the heat exchanger 204 so that the hot water has the original set temperature (T). In step S750, CPU 301 determines that circulation pump 207 is not normally stopped, and outputs an alarm from notification device 306.

Fig. 8 is a diagram showing an example of the second operation of the hot water supply apparatus 200. The processing shown in fig. 8 is a processing flow of the CPU 301 when the second operation described in fig. 4 is implemented. In some aspect, the CPU 301 may read a program to perform the processing of fig. 8 from the memory 302 and execute the program. In another aspect, some or all of the processing may be implemented in the form of a combination of circuit elements configured to perform the processing.

In step S805, the CPU 301 sets the state of the hot water supply device 200 to the hot water supply standby mode. In step S810, the CPU 301 accepts a command for real-time hot water ON (ON). In some aspect, the CPU 301 may accept a command for real-time hot water ON (ON) based ON the real-time hot water switch of the remote controller 307 having been pressed. ON the other hand, the CPU 301 may receive a command for turning ON (ON) the hot water in real time by pressing a button or the like of the hot water supply apparatus 200 itself.

In step S815, when entering the real-time hot water circulation mode, the CPU 301 determines whether or not the set temperature of hot water supply is equal to or lower than the limit temperature (Th 1). When it is determined that the set temperature of the hot water supply is equal to or lower than the limit temperature (Th1) (YES in step S815), the CPU 301 proceeds to step S820. If not (NO in step S815), the CPU 301 moves control to step S810. In one aspect, when returning control to step S810, the CPU 301 may notify the user that the real-time hot water circulation mode is not entered from the notification device 306.

In step S820, the CPU 301 sets the state of the hot water supply device 200 to the real-time hot water standby mode. In step S825, the CPU 301 determines whether the hot water supply device 200 satisfies the combustion start condition. The combustion start condition includes, for example, whether or not the current temperature of the hot water is lower than a set temperature, whether or not the circulation pump 207 reacts. When having determined that the hot water supply device 200 satisfies the combustion start condition (YES in step S825), the CPU 301 proceeds to step S830. If not (NO in step S825), the CPU 301 proceeds to step S820. In one aspect, when returning control to step S820, CPU 301 may notify the user that hot water supply device 200 does not satisfy the combustion start condition from notification device 306.

In step S830, the CPU 301 outputs an ON (ON) instruction to the circulation pump 207. When an ON (ON) command is input from CPU 301, circulation pump 207 operates to circulate warm water.

In step S835, after the start of the real-time hot water circulation, the CPU 301 sets the upper limit of the set temperature of the hot water supply to the limit temperature (Th1) or less. That is, when the hot water supply device 200 is operating in the real-time hot water circulation mode, the CPU 301 does not receive an input of a temperature setting higher than the limit temperature (Th 1).

In step S840, the CPU 301 also sets the state of the hot water supply apparatus 200 to the real-time hot water circulation end based on the temperature of the hot water during circulation reaching the set temperature. In step S845, the CPU 301 outputs an OFF (OFF) instruction to the circulation pump 207. The circulation pump 207 is stopped when a disconnection (OFF) instruction is input from the CPU 301. In step S850, the CPU 301 cancels the upper limit setting of the set temperature of hot water supply set in step S835. After the upper limit setting of the set temperature is released, the CPU 301 may accept input of a temperature setting higher than the limit temperature (Th 1).

[ other device structures ]

Fig. 9 is a diagram showing another example of the hot water supply device not including the circulation port. The hot water supply device 900 includes a bypass path upstream and downstream of the circulation pump 207, a flow rate detector 901 provided in the bypass path, and a backflow prevention valve 902, as compared with the hot water supply device 200.

With the hot water supply apparatus 900 including the flow rate detector 901, the controller 250 can determine whether the circulation pump 207 is out of order or the user opens the valve 120 to allow the warm water to flow out of the hot water supply plug 140 when the flow rate detector 202 detects the flow of water or warm water after the real-time hot water circulation mode is finished.

Specifically, in a case where the controller 250 sets the circulation pump 207 OFF (OFF), when the flow rate detector 202 detects water flow and the flow rate detector 901 does not detect water flow, the controller 250 may determine that an ON (ON) failure of the circulation pump 207 occurs. The reason is that: during the operation of the circulation pump 207, water or warm water is sucked in by the circulation pump 207 and flows into the circulation pump 207 preferentially over the flow rate detector 901, and as a result, the flow rate detector 901 detects almost no water flow.

Conversely, when the controller 250 turns the circulation pump 207 OFF (OFF), and when both the flow rate detector 202 and the flow rate detector 901 detect water flow, the controller 250 may determine that the circulation pump 207 has not failed to turn ON (ON) (the user opens the valve 120 to allow warm water to flow out of the hot water supply plug 140). The reason is that: when the circulation pump 207 is stopped and the user opens the valve 120 to cause the hot water to flow out from the hot water supply plug 140, the water or the hot water does not preferentially flow into the circulation pump 207, and as a result, the water or the hot water also flows into the flow rate detector 901.

As described above, the hot water supply device 200 according to the present embodiment heats hot water in a range of a predetermined limit temperature or less in the real-time hot water circulation mode. Alternatively, when the set temperature of the hot water supply exceeds a predetermined limit temperature, the hot water supply device 200 does not shift to the real-time hot water circulation mode. By the control, the temperature of the warm water in the real-time hot water circulation mode and at the end of the real-time hot water circulation mode is limited to a temperature at which the user is not scalded. Therefore, even if the user opens the valve 130 when the circulation pump 207 malfunctions, the user is not burned.

The features of the technique disclosed as above can be summarized as follows.

(structure 1) a hot water supply device according to an embodiment includes: a first piping connected to the water inlet; a flow rate detector for detecting a flow rate of water in the first pipe; a heating mechanism for heating the water flowing in from the first pipe; and a second pipe through which the hot water heated by the heating means flows. The second pipe is connected to the first pipe via an external third pipe. The hot water supply device further includes a circulation pump disposed on a path of the first pipe and configured to send warm water in the third pipe in a direction toward the heating mechanism when the hot water supply device is operated, and a control device configured to control the circulation pump and the heating mechanism. The control device operates the circulation pump based on the execution command received from the real-time hot water circulation mode, and adjusts the heating temperature of the heating mechanism so that the temperature of the hot water in the real-time hot water circulation mode becomes equal to or lower than the limit temperature when the setting of the hot water outflow temperature exceeds the predetermined limit temperature.

(structure 2) a hot water supply apparatus according to another embodiment includes: a first piping connected to the water inlet; a flow rate detector for detecting a flow rate of water in the first pipe; a heating mechanism for heating the water flowing in from the first pipe; and a second pipe through which the hot water heated by the heating means flows. The second pipe is connected to the first pipe via an external third pipe. The hot water supply device further includes a circulation pump disposed on a path of the first pipe and configured to send warm water in the third pipe in a direction toward the heating mechanism when the hot water supply device is operated, and a control device configured to control the circulation pump and the heating mechanism. The control device determines whether the hot water outflow temperature is set to be equal to or lower than a predetermined limit temperature based on the reception of the execution command of the real-time hot water circulation mode, and operates the hot water supply device in the real-time hot water circulation mode based on the hot water outflow temperature set to be equal to or lower than the limit temperature.

(configuration 3) the hot water supply apparatus according to the aspect includes, in addition to the configuration 2, a notification device that notifies a user of information, and the notification device notifies the user that the real-time hot water circulation mode is not entered, based on the setting of the hot water outflow temperature exceeding the limit temperature.

(structure 4) the hot water supply apparatus according to still another embodiment includes: a first piping connected to the water inlet; a flow rate detector for detecting a flow rate of water in the first pipe; a heating mechanism for heating the water flowing in from the first pipe; and a second pipe through which the hot water heated by the heating means flows. The second pipe is connected to the first pipe via an external third pipe. The hot water supply device further includes a circulation pump disposed on a path of the first pipe and configured to send warm water in the third pipe in a direction toward the heating mechanism when the hot water supply device is operated, and a control device configured to control the circulation pump and the heating mechanism. The control device stops the circulation pump and ends the real-time hot water circulation mode based on the fact that the hot water supply device is operating in the real-time hot water circulation mode, so that the temperature of the hot water during circulation is equal to or lower than a predetermined limit temperature, determines that the circulation of the hot water is ended based on the fact that the detected amount of the flow rate obtained by the flow rate detector is less than the first flow rate after the real-time hot water circulation mode is ended, and releases the limit of the heating temperature of the heating mechanism based on the determined end of the circulation of the hot water.

(structure 5) the hot water supply device according to an aspect includes a memory for storing settings of the hot water supply device in addition to the structure 4, and the control device receives an input of a setting of a hot water outflow temperature from the remote controller and saves the input setting of the hot water outflow temperature in the memory. The releasing of the limitation of the heating temperature of the heating mechanism includes: when an input of a temperature setting exceeding the limit temperature is received, after the real-time hot water circulation mode is ended, the heating temperature of the heating means is increased based on the setting of the hot water outflow temperature read from the memory.

(configuration 6) the hot water supply device according to the aspect includes, in addition to configuration 4, a notification device that notifies a user of information, and the notification device notifies a failure that the circulation pump does not stop, that is, a failure of the hot water supply device, based on a fact that a detected amount of the flow rate obtained by the flow rate detector is less than the first flow rate even if a predetermined time has elapsed from the end of the real-time hot water circulation mode.

(structure 7) the hot water supply apparatus according to an aspect includes, in addition to the structure 4: a fourth pipe that bypasses the circulation pump on the upstream side and the downstream side of the circulation pump in the first pipe; and another flow rate detector provided on a path of the fourth pipe, wherein the control device detects a failure of the circulation pump based on the fact that the flow rate detected by the another flow rate detector is less than the second flow rate when the real-time hot water circulation mode is ended and the detected flow rate by the flow rate detector is equal to or greater than the first flow rate.

(structure 8) the hot water supply apparatus according to the aspect of the present invention is configured such that, in addition to any one of the structures 1 to 7, the temperature is limited to the maximum set temperature of the hot water in the real-time hot water circulation mode.

(structure 9) in the hot water supply apparatus according to the aspect, in addition to any one of the structures 1 to 8, a valve is disposed in a path of the third pipe, and the valve regulates a flow of the hot water in the third pipe in a direction from the second pipe to the first pipe.

(structure 10) the hot water supply apparatus according to an aspect of the present invention includes, in addition to any one of structures 1 to 9: a fifth pipe connecting the downstream side of the circulation pump in the first pipe and the second pipe; and a flow rate adjusting device that adjusts the amount of water that flows from the first pipe into the second pipe via the fifth pipe.

The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, rather than the description above, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein. The invention described in the embodiments and the modifications may be implemented alone or in combination as much as possible.

Claims

1. A hot water supply apparatus comprising:

a first pipe connected to the water inlet;

a flow rate detector that detects a flow rate of water in the first pipe;

a heating mechanism that heats water flowing in from the first pipe; and

a second pipe through which the hot water heated by the heating means flows,

the second pipe is connected to the first pipe via an external third pipe,

the hot water supply apparatus further includes:

a circulation pump disposed on a path of the first pipe and configured to send warm water in the third pipe in a direction of the heating mechanism during operation; and

a control device for controlling the circulation pump and the heating mechanism,

the control device makes the circulating pump work based on the execution command of receiving the real-time hot water circulating mode,

when the hot water outflow temperature is set to exceed a predetermined limit temperature, the heating temperature of the heating means is adjusted so that the temperature of the hot water in the real-time hot water circulation mode becomes equal to or lower than the limit temperature.

2. A hot water supply apparatus comprising:

a first pipe connected to the water inlet;

a flow rate detector that detects a flow rate of water in the first pipe;

a heating mechanism that heats water flowing in from the first pipe; and

a second pipe through which the hot water heated by the heating means flows,

the second pipe is connected to the first pipe via an external third pipe,

the hot water supply apparatus further includes:

the control device judges whether the hot water outflow temperature is set to be equal to or lower than a predetermined limit temperature based on the reception of the execution command of the real-time hot water circulation mode,

operating the hot water supply device in a real-time hot water circulation mode based on the setting of the hot water outflow temperature to be below the limit temperature.

3. A hot water supply apparatus comprising:

a first pipe connected to the water inlet;

a flow rate detector that detects a flow rate of water in the first pipe;

a heating mechanism that heats water flowing in from the first pipe; and

a second pipe through which the hot water heated by the heating means flows,

the second pipe is connected to the first pipe via an external third pipe,

the hot water supply apparatus further includes:

the control device limits the heating temperature of the heating mechanism based on the fact that the hot water supply device operates in a real-time hot water circulation mode so that the temperature of the hot water in the circulation process is less than or equal to a predetermined limit temperature,

stopping the circulating pump, ending the real-time hot water circulation mode,

determining that the circulation of the warm water is completed based on a detected amount of the flow rate obtained by the flow rate detector being less than a first flow rate after the real-time hot water circulation mode is completed,

and releasing the limitation of the heating temperature of the heating mechanism based on the judgment that the circulation of the warm water is finished.