Water heater

Abstract

To provide a water heater capable of preventing proliferation of Legionella bacteria and the like.SOLUTION: A water heater includes: a hot water storage tank for storing hot water heated by a heat source; a hot water supply circuit for supplying hot water to a supply port from the hot water storage tank; return flow piping for returning the hot water in the hot water supply circuit to the hot water storage tank; a return pump provided in the return flow piping; and a control part. The control part executes a hot water storage tank sterilization mode in which the hot water temperature in the hot water storage tank is boiled to the temperature capable of sterilizing Legionella bacteria and the like, and sterilization of the hot water storage tank is performed for predetermined time, and a hot water supply circuit sterilization mode in which, after predetermined time is elapsed, the return pump is ON-controlled, the hot water in the hot water storage tank is circulated in the hot water supply circuit, and the hot water supply circuit is sterilized.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a water heater.

Background Art

[0002] Patent Document 1 discloses a water heater including a hot water storage tank that stores hot water heated by a heat source, a supply passage that supplies the hot water from the hot water storage tank to a supply port, a return passage that returns the hot water in the supply passage to the hot water storage tank, and a return pump provided in the return passage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a water heater capable of preventing the growth of Legionella bacteria and the like.

Means for Solving the Problems

[0005] The water heater in the present disclosure includes a hot water storage tank that stores hot water heated by a heat source, a hot water supply circuit that supplies the hot water from the hot water storage tank to a supply port, a return pipe that returns the hot water in the hot water supply circuit to the hot water storage tank, a return pump provided in the return pipe, and a control unit. The control unit executes a hot water storage tank sterilization mode in which the water temperature in the hot water storage tank is raised to a temperature at which sterilization of Legionella bacteria and the like is possible to sterilize the hot water storage tank for a predetermined time, and after the predetermined time has elapsed, executes a hot water supply circuit sterilization mode in which the return pump is controlled to be ON and the hot water in the hot water storage tank is circulated through the hot water supply circuit to sterilize the hot water supply circuit.

Effects of the Invention

[0006] According to the present disclosure, by executing the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode, the growth of Legionella bacteria and the like can be prevented.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] (Findings and the like underlying the present disclosure) When the inventors arrived at the present disclosure, there was a water heater including a hot water storage tank for storing hot water heated by a heat source, a supply passage for supplying the hot water from the hot water storage tank to a supply port, a return passage for returning the hot water in the supply passage to the hot water storage tank, and a return pump provided in the return passage. Since this water heater is configured to return the hot water in the supply passage to the hot water storage tank through the return passage, the inventors discovered the problem that it is necessary to prevent the growth of Legionella bacteria and the like in the return passage, and in order to solve this problem, they arrived at the configuration of the subject matter of the present disclosure. Therefore, the present disclosure provides a water heater capable of preventing the growth of Legionella bacteria and the like by executing the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode.

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. However, there may be cases where more detailed description than necessary is omitted. For example, there may be cases where detailed description of well-known matters or duplicate description of substantially the same configuration is omitted. Note that the attached drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0010] (Embodiments) [Configuration] FIG. 1 is a diagram showing the configuration of the water heater 1. As shown in Fig. 1, the water heater 1 includes a heat pump unit 2 and a hot water storage unit 3. The heat pump unit 2 includes a heat pump circuit 20. The heat pump circuit 20 includes a compressor 21, a four-way valve 22, a first heat exchanger 23, a decompression device 24, a second heat exchanger 25, and a blower fan 26. The compressor 21, the four-way valve 22, the first heat exchanger 23, the decompression device 24, and the second heat exchanger 25 are connected by a refrigerant pipe 27.

[0011] The hot water storage unit 3 includes a hot water storage tank 30. Connected to the hot water storage tank 30 are a boiling-up circuit 40, a hot water supply circuit 60, and a water supply circuit 70 for supplying city water to the hot water storage tank 30.

[0012] The boiling-up circuit 40 is a circuit connecting the hot water storage tank 30 and the first heat exchanger 23. A heating pipe 41 for heating hot water is arranged in the hot water storage tank 30. At the outlet of the heating pipe 41, a first confluence part 42 and a circulation pump 43 are connected in sequence. The circulation pump 43 is connected to the first heat exchanger 23, and to the first heat exchanger 23, a flow rate sensor 44, a pressure sensor 45, a bubble separator 46, and a heater 47 are connected in sequence. The heater 47 is connected to a first connection port 48A of a first three-way valve 48, and the heating pipe 41 is connected to a second connection port 48B of the first three-way valve 48. A heat radiation panel 49 for heating is connected to a third connection port 48C of the first three-way valve 48, and the heat radiation panel 49 is connected to the first confluence part 42.

[0013] A plate-type heat exchanger or a double-pipe type heat exchanger is used for the first heat exchanger 23. In the first heat exchanger 23, heat exchange is performed between the refrigerant flowing through the heat pump circuit 20 and the heat medium of the boiling-up circuit 40.

[0014] A part of the heat pump circuit 20 and the boiling-up circuit 40 is housed in a first housing 51 and arranged outside the house. The remaining part of the hot water storage tank 30 and the boiling-up circuit 40 is housed in a second housing 52 and arranged, for example, in a basement mechanical room of the house.

[0015] The hot water supply circuit 60 includes a hot water supply pipe 61 for high-temperature water, and the hot water supply pipe 61 is connected to the upper part of the hot water storage tank 30. A first branch part 62 and a temperature control valve 63 are sequentially connected to the hot water supply pipe 61, and a hot water supply facility 64 such as a kitchen or a bath is connected to the temperature control valve 63.

[0016] The water supply circuit 70 includes a water supply pipe 71 for supplying city water to the hot water storage tank 30. A second branch part 72 and a second confluence part 73 are sequentially connected to the water supply pipe 71 from the upstream. The second branch part 72 and the temperature control valve 63 are connected by a branch water supply pipe 74 for supplying city water to the temperature control valve 63. In the present embodiment, the first branch part 62 and the second confluence part 73 are connected by a reflux pipe 75. The first branch part 62 is located between the temperature control valve 63 and the hot water storage tank 30. A return pump 76 and a check valve 77 are sequentially connected to the reflux pipe 75 from the upstream.

[0017] The hot water supply machine 1 includes a hot water storage tank 30 for storing hot water heated by a heat pump unit (heat source) 2, a hot water supply circuit 60 for supplying hot water from the hot water storage tank 30 to a hot water supply facility (supply port) 64 such as a kitchen or a bath, a reflux pipe 75 for returning the hot water in the hot water supply circuit 60 to the hot water storage tank 30, a return pump 76 provided in the reflux pipe 75, and a control unit 100. A sensor 81 for measuring the hot water temperature of the hot water storage tank 30 is attached to the hot water storage tank 30.

[0018] The control unit 100 executes a hot water storage tank sterilization mode TM and a hot water supply circuit sterilization mode KM. Each mode TM and KM is executed at a frequency of about once a week. In the hot water storage tank sterilization mode TM, the hot water temperature in the hot water storage tank 30 is boiled up to a temperature (60°C or higher) at which sterilization of Legionella bacteria and the like is possible, and sterilization inside the hot water storage tank 30 is performed for a predetermined time T. Further, in the hot water supply circuit sterilization mode KM, after the above-mentioned predetermined time T has elapsed, the return pump 76 is controlled to be ON, and the high-temperature hot water in the hot water storage tank 30 is circulated through the hot water supply circuit 60 to sterilize the inside of the hot water supply circuit 60. The ON time of the return pump 76 at this time is preset in consideration of the pipe length and stored in the storage unit 101 of the control unit 100. Further, the control unit 100 includes a correction unit 102 that corrects the ON time of the return pump 76 according to the measurement value of the sensor 81. For example, when the hot water temperature in the hot water storage tank 30 is high and the measurement value of the sensor 81 is high, the ON time of the return pump 76 may be corrected to be short, and when the measurement value of the sensor 81 is low, the ON time of the return pump 76 may be corrected to be long.

[0019] In addition to executing each mode TM and KM, the control unit 100 executes a control mode SM that ON / OFF controls the operation of the return pump 76 during the suspension of hot water supply to the hot water supply facility 64. The state of the suspension of hot water supply is detected by, for example, a flow sensor (not shown) disposed in the hot water supply circuit 60. The ON time and OFF time at this time are preset in consideration of the pipe length and stored in the storage unit 101 of the control unit 100. The correction unit 102 may correct the ON time in the control mode SM according to the measurement value of the sensor 81 in the same manner as described above.

[0020] [Boiling-up operation] The control unit 100 drives the compressor 21 of the heat pump circuit 20 and the circulation pump 43 of the boiling-up circuit 40. When the compressor 21 of the heat pump circuit 20 is driven, high-temperature and high-pressure refrigerant flows into the first heat exchanger 23 through the four-way valve 22. This refrigerant is decompressed by the decompression device 24 and evaporated in the second heat exchanger 25 to become low-temperature and low-pressure refrigerant, and then returns to the suction port of the compressor 21 through the four-way valve 22. When the circulation pump 43 of the boiling-up circuit 40 is driven, the heat medium flows through the first heat exchanger 23, refluxes to the heating pipe 41 in the hot water storage tank 30, and returns to the suction port of the circulation pump 43 through the first confluence portion 42.

[0021] In the first heat exchanger 23, heat exchange is performed between the refrigerant flowing through the heat pump circuit 20 and the heat medium flowing through the boiling-up circuit 40, and the high-temperature heat medium refluxes to the heating pipe 41, and the water in the hot water storage tank 30 is boiled up.

[0022] [Hot water supply operation] In the hot water supply device 64, for example, when a faucet (supply port) is opened, the hot water in the hot water storage tank 30 passes through the hot water supply pipe 61, through the first branch portion 62, and reaches the temperature control valve 63. In the temperature control valve 63, the hot water in the hot water storage tank 30 supplied through the hot water supply pipe 61 is mixed with the city water supplied through the branch water supply pipe 74, and after temperature adjustment, it is supplied from the faucet.

[0023] [Sterilization operation] When the hot water storage tank 30 has not been boiled up for a certain period, when the measured value of the sensor 81 attached to the hot water storage tank 30 falls below 60 to 65 °C, due to the decrease in the hot water temperature of the hot water storage tank 30, the generation of Legionella bacteria and the like is a problem.

[0024] In the present embodiment, the control unit 100 periodically executes the hot water storage tank sterilization mode TM about once a week, and then executes the hot water supply circuit sterilization mode KM. First, the hot water storage tank 30 is forcibly boiled up. The hot water storage tank sterilization mode TM boils up the hot water storage tank 30 to 60 °C or higher at which sterilization of Legionella bacteria and the like is possible, and sterilizes the hot water storage tank 30 for a predetermined time T. Further, in the hot water supply circuit sterilization mode KM, after the predetermined time T has elapsed, the return pump 76 is controlled to be ON, and the high-temperature hot water in the hot water storage tank 30 is circulated through the hot water supply circuit 60 to sterilize the hot water supply circuit 60.

[0025] In the present embodiment, since the hot water storage tank 30 can be sterilized in the hot water storage tank sterilization mode TM, and in the hot water supply circuit sterilization mode KM, the hot water temperature in the hot water supply pipe 61 can be raised to a temperature range at which sterilization of Legionella bacteria and the like is possible, the hot water supply pipe 61 can be sterilized.

[0026] During the execution of the hot water storage tank sterilization mode TM and the hot water supply circuit sterilization mode KM, the control unit 100 may display "sterilization in progress" on the display unit (not shown) of the remote controller. If "sterilization in progress" or the like is displayed on the display unit (not shown), the user can recognize whether the hot water storage tank sterilization mode TM is being executed or the hot water supply circuit sterilization mode KM is being executed, and the usability is improved.

[0027] [Pipe length] FIG. 2 is a diagram showing the relationship between the pipe length and the ON time (predetermined time T) of the return pump 76 in the hot water supply circuit sterilization mode KM. The pipe length (m) is the total value of the pipe length of the hot water supply pipe 61, the pipe length of the reflux pipe 75, and the pipe length of the water supply pipe 71 from the second confluence portion 73 to the hot water storage tank 30. The discharge capacity of the return pump 76 is set to 5 liters / minute. The ON time (minutes) of the return pump 76 is set as the time required to circulate at least 5 rounds of the total pipe length of a part of the hot water supply pipe 61, the reflux pipe 75, and the water supply pipe 71, taking into account the heat dissipation to the pipe.

[0028] If the pipe length is about 5 m, the required operation time (predetermined time T: ON time) may be about 30 to 40 seconds. As the pipe length increases, the required operation time becomes longer. When the pipe length reaches 55 m, the required operation time exceeds 6 minutes. That is, the predetermined time T changes according to the pipe length (m), and desirably, it is set as the time required to circulate at least 5 rounds within the pipe length for which the return pump 76 is ON-controlled to circulate hot water.

[0029] [Reflux operation] When the above-described hot water supply operation stops, at least the temperature of the hot water remaining in the hot water supply pipe 61 decreases due to the influence of the ambient temperature. When the hot water supply operation is restarted after the hot water supply operation has stopped for a long time, cold water may be supplied to the faucet (supply port) through the hot water supply pipe 61, and the user may feel discomfort. In the present embodiment, the control unit 100 controls the operation of the return pump 76 to be ON and OFF during the stop of the hot water supply from the supply port, and executes the control mode SM. The ON time of the return pump 76 is set as the time required to circulate the hot water supply pipe 61 about 5 rounds.

[0030] When the return pump 76 is turned on, the hot water remaining in the hot water supply pipe 61 enters the hot water storage tank 30 from the second confluence part 73 through the return pipe 75, and the high-temperature hot water from the upper part of the hot water storage tank 30 returns to the hot water supply pipe 61. According to this, the water temperature in the hot water supply pipe 61 is kept at a high temperature. Therefore, when the hot water supply operation resumes after being stopped for a long time, cold water is not supplied to the faucet (supply port) through the hot water supply pipe 61, and high-temperature hot water is supplied to the faucet (supply port) from the start of the resumption of the hot water supply operation.

[0031] Also, the ON time of the return pump 76 is set to a time sufficient to circulate through the hot water supply pipe 61 at least five times. Since the operation of the return pump 76 is stopped during the other OFF time, the power consumption can be suppressed.

[0032] That is, in the present embodiment, both heat preservation in the hot water supply pipe 61 during hot water supply stop and suppression of power consumption can be achieved.

[0033] Also, in the present embodiment, when the water in the hot water storage tank 30 has not been boiled up for a certain period, before controlling the return pump 76 to be turned on and off, the control unit 100 forcibly boils up the water in the hot water storage tank 30. Therefore, at the same time as turning on the return pump 76, hot water with a high water temperature can be supplied from the hot water storage tank 30 to the hot water supply pipe 61, the ON time of the return pump 76 can be shortened, and power consumption can be suppressed.

[0034] In the control mode SM, the control unit 100 may correct the ON time of the return pump 76 according to the measured value of the sensor 81. When the water temperature in the hot water storage tank 30 is higher than a predetermined temperature, the ON time of the return pump 76 is corrected to be shorter than a preset predetermined time T. When the water temperature is lower than the predetermined temperature, the ON time of the return pump 76 is corrected to be longer than the set predetermined time T. When the water temperature in the hot water storage tank 30 is high, the return pump 76 may be stopped immediately.

[0035] As described above, the above embodiments have been described as examples disclosed in the present application. However, the technology in the present disclosure is not limited to this, and it can also be applied to embodiments with changes, replacements, additions, omissions, etc. In addition, it is also possible to combine the components described in the above embodiments to form a new embodiment.

[0036] In this embodiment, the heat pump circuit 20 is used as the heat source, but heaters, gas appliances, etc. can be applied as the heat source.

[0037] (Supplementary Note) With the description of the above embodiments, the following technologies are disclosed.

[0038] (Technology 1) A hot water storage tank for storing hot water heated by a heat source, a hot water supply circuit for supplying hot water from the hot water storage tank to a supply port, a reflux pipe for returning the hot water in the hot water supply circuit to the hot water storage tank, a return pump provided in the reflux pipe, and a control unit. The control unit boils the hot water temperature in the hot water storage tank to a temperature capable of sterilizing Legionella bacteria and other bacteria, and performs a hot water storage tank sterilization mode for sterilizing the hot water storage tank for a predetermined time. After the predetermined time has elapsed, the return pump is controlled to be ON, and the hot water in the hot water storage tank is circulated through the hot water supply circuit to sterilize the inside of the hot water supply circuit, and a hot water supply circuit sterilization mode is executed. According to this, sterilization of the inside of the hot water supply circuit becomes possible together with sterilization of the hot water storage tank.

[0039] (Technology 2) The ON time of the return pump is set to be at least the time for circulating five times within the pipe length for circulating hot water by controlling the return pump to be ON. The hot water supply machine according to Technology 1. According to this, sterilization of the inside of the hot water supply circuit becomes possible together with sterilization of the hot water storage tank.

[0040] (Technology 3) The hot water supply machine according to Technology 1, further comprising a sensor for measuring the hot water temperature in the hot water storage tank, and the control unit comprising a correction unit for correcting the ON time of the return pump according to the measured value of the sensor. According to this, by correcting the ON time of the return pump, appropriate sterilization can be achieved regardless of whether the hot water temperature in the hot water storage tank is high or low.

[0041] (Technical 4) The hot water supply apparatus according to Technical 1, wherein the control unit displays on a display unit of a remote controller that the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode are being executed. According to this, the user can recognize whether the hot water storage tank sterilization mode or the hot water supply circuit sterilization mode is being executed, improving usability.

[0042] (Technical 5) The hot water supply apparatus according to Technical 1, wherein the control unit controls ON and OFF of the return pump during stoppage of hot water supply from the supply port. According to this, during stoppage of hot water supply, it is possible to achieve both heat retention in the hot water supply pipe and suppression of power consumption.

[0043] (Technical 6) The hot water supply apparatus according to any one of Technical 1 to 5, wherein when the hot water storage tank has not been boiled up for a certain period, after forcibly boiling up the hot water storage tank, the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode are executed. According to this, a sterilization effect can be surely achieved by the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode.

[0044] (Technical 7) The hot water supply apparatus according to Technical 6, wherein the boiling-up temperature is 60°C or higher. According to this, a sterilization effect can be surely achieved by the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode.

Industrial Applicability

[0045] The present invention can be used for a hot water supply apparatus including a reflux pipe for returning hot water in a hot water supply circuit to a hot water storage tank and a return pump provided in the reflux pipe.

Explanation of Signs

[0046] 1 Hot water supply apparatus 2 Heat pump unit 3 Hot water storage unit 20 Heat pump circuit 30 Hot water storage tank 40 Rising circuit 51 First housing 52 Second housing 60 Hot water supply circuit 61 Hot water supply pipe 63 Temperature control valve 70 Water supply circuit 71 Water supply pipe 74 Branch water supply pipe 75 Return pipe 76 Return pump 100 Control unit 101 Memory unit 102 Correction unit

Claims

1. A hot water storage tank for storing hot water heated by a heat source, a hot water supply circuit for supplying hot water from the hot water storage tank to a supply port, a reflux pipe for returning the hot water in the hot water supply circuit to the hot water storage tank, a return pump provided in the reflux pipe, and a control unit, wherein the control unit executes a hot water storage tank sterilization mode in which the hot water temperature in the hot water storage tank is raised to a temperature at which sterilization of Legionella bacteria and the like is possible, and the hot water storage tank is sterilized for a predetermined time, and after the predetermined time has elapsed, controls the return pump to be ON, circulates the hot water in the hot water storage tank through the hot water supply circuit, and executes a hot water supply circuit sterilization mode for sterilizing the inside of the hot water supply circuit, a hot water supply machine.

2. The ON time of the return pump is set to a time for circulating at least 5 times within the pipe length for circulating hot water by controlling the return pump to be ON, The hot water supply machine according to Claim 1.

3. Comprising a sensor for measuring the hot water temperature in the hot water storage tank, wherein the control unit comprises a correction unit for correcting the ON time of the return pump according to the measured value of the sensor, The hot water supply machine according to Claim 1.

4. The control unit displays on the display unit of the remote control that the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode are being executed, The hot water supply machine according to Claim 1.

5. The control unit controls the return pump to be ON and OFF during the stop of hot water supply from the supply port, The hot water supply machine according to Claim 1.

6. The control unit when the hot water storage tank has not been boiled up for a certain period, forcibly boils up the hot water storage tank and then executes the hot water storage tank sterilization mode and the hot water supply circuit sterilization mode, The hot water supply machine according to any one of Claims 1 to 5.

7. The boiling-up temperature is 60°C or higher, The hot water supply machine according to Claim 6.

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