JP2012057853A - Electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric water heater that completes boiling up at proper time every day, without a user taking time and effort to change boil-up completion time in each case, under the condition that used hours of hot water vary from day to day.SOLUTION: The electric water heater includes: a hot water storage tank; a heater which carries out a boiling-up operation for boiling up hot water in the hot water storage tank; a hot water residual quantity detector which detects a residual quantity of hot water in the hot water storage tank; a time-period divider which at least divides one day into a first time period and a second time period earlier than the first to manage time; an extra-boiling controller which carries out the boiling-up operation when the residual quantity of hot water reaches a predetermined value or less, at the first time period; a total-amount boiling-up controller which carries out the boiling-up operation so that a total amount of hot water in the hot water storage tank boils up, at the second time period; and a time-period division setter which enables the user to preset time when the first time period and the second time period are divided, in each schedule, such as date and day or term.

Description

  The present invention relates to an electric water heater.

  In electric water heaters, add hot water to prevent boiling out when the amount of hot water in the hot water storage tank is fully boiled (for example, at midnight) and when the remaining hot water volume falls below a specified value. There is known a technique of controlling by dividing a time zone (for example, daytime time zone) in which a hot water boiling operation is performed (see, for example, Patent Document 1).

Japanese Patent No. 399199

  However, for example, an electric water heater used in an environment where the hot water usage time varies depending on the day, such as a commercial water heater used in a store whose business hours vary depending on the day of the week, has the following problems. If the time to complete boiling of the hot water storage tank is set to a time later than the hot water start time (for example, the start time of the store's business hours), there will be enough hot water storage when hot water usage starts. There is a risk of running out of hot water. Therefore, in order to reliably prevent hot water from running out, it is necessary to complete the boiling of the hot water storage tank by the start time of hot water use. For this reason, if the completion time of boiling of the total amount was set according to the date when the hot water usage start time was earliest, on the day when the hot water usage start time was late, Until the start of use, energy is wasted due to heat loss from the hot water storage tank. In order to avoid this waste, every time the hot water use start time is changed, it is necessary for the user to set the completion time of the total boiling, which is complicated.

  The present invention has been made in order to solve the above-described problems. In an environment where the hot water usage time varies depending on the day, the user can take the effort to change the boiling completion time each time, without taking the user every day. An object is to provide an electric water heater that can complete boiling at an appropriate time every time.

  An electric water heater according to the present invention includes a hot water storage tank, heating means that is driven by electricity and performs a boiling operation for boiling hot water in the hot water storage tank, and a remaining hot water amount detection for detecting a remaining hot water amount or a remaining heat amount in the hot water storage tank. Means, a time zone dividing means for managing time by dividing at least a first day into a first time zone and a second time zone before that, and detected in the first time zone Boiling control means for performing boiling increase control to increase the amount of hot water in the hot water storage tank by performing a boiling operation when the remaining hot water volume or the residual heat volume becomes a predetermined value or less, and in the hot water storage tank in the second time zone The whole amount boiling control means for performing the whole amount boiling control that performs the boiling operation so that all of the hot and cold water is boiled, and the first time zone and the second time zone for each schedule such as date, day of the week or period, etc. Time The is one that has a time zone division setting means that can be set in advance.

  According to the present invention, in an environment where the hot water usage time varies depending on the day, boiling can be completed at an appropriate time every day without causing the user to change the boiling completion time each time. It becomes possible. For this reason, while running out of hot water reliably, energy saving can be achieved.

It is a block diagram which shows Embodiment 1 of the electric water heater of this invention. It is an external view of the remote control in Embodiment 1 of this invention. It is an external view of the remote control in Embodiment 1 of this invention. It is an external view of the remote control in Embodiment 1 of this invention. It is a figure which shows an example of the relationship between the amount of hot water in the hot water storage tank and boiling timing in Embodiment 1 of this invention. It is a figure which shows an example of the relationship between the amount of hot water in a hot water storage tank, and a boiling timing. It is a figure which shows an example of the relationship between the amount of hot water in the hot water storage tank and boiling timing in Embodiment 2 of this invention. It is a figure which shows an example of the relationship between the amount of residual heat in a hot water storage tank, and a boiling timing when a regular holiday is set in Embodiment 3 of this invention. It is a flowchart of the routine which a water heater control part performs when the day or the next day is set as a regular holiday in Embodiment 4 of this invention. It is an external view of the remote control in Embodiment 5 of this invention. It is a figure which shows an example of the relationship between the amount of hot water in the hot water storage tank and boiling timing in Embodiment 5 of this invention. It is a figure which shows an example of the relationship between the amount of hot water in the hot water storage tank and boiling timing in Embodiment 5 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing Embodiment 1 of an electric water heater according to the present invention. As shown in FIG. 1, a hot water storage tank 11 is provided inside the electric water heater main body 10. A hot water supply pipe 21 is connected to the lower part of the hot water storage tank 11, and a hot water supply pipe 22 is connected to the upper part of the hot water storage tank 11. The hot water supply pipe 22 is connected to a hot water outlet such as a faucet or a shower, for example, and functions to send hot water in the hot water storage tank 11 to the hot water outlet. When hot water in the hot water storage tank 11 is sent to the outside through the hot water supply pipe 22, water is supplied to the hot water storage tank 11 from the water supply pipe 21 correspondingly. Thereby, the quantity of the hot water in the hot water storage tank 11 is always kept constant.

  The hot water storage tank 11 is connected to the heat pump unit 200 (heating means) by a heating circulation circuit 23 equipped with a water pump (not shown). During the boiling operation for boiling hot water, the heat pump unit 200 and the heating circulation circuit 23 are driven. In this boiling operation, the water taken out from the lower part of the hot water storage tank 11 is sent to the heat pump unit 200 via the heating circuit 23, and hot water is boiled by giving heat to the water from the refrigerant of the heat pump. The boiled hot water is sent to the hot water storage tank 11 through the heating circulation circuit 23 and flows into the hot water storage tank 11 from above. By such a boiling operation, hot water is stored from the upper part to the lower part in the hot water storage tank 11.

  In the hot water storage tank 11, temperature sensors 41, 42, 43, and 44 are installed at locations where the amount of hot water stored is 0 L, 150 L, 300 L, and 400 L, respectively. The temperature information of each part detected by these temperature sensors 41, 42, 43, 44 is transmitted to a water heater controller 31 provided inside the electric water heater main body 10. The water heater controller 31 can calculate the remaining hot water amount (hot water storage amount) and the residual heat amount (heat storage amount) in the hot water storage tank 11 based on the detection results of the temperature sensors 41, 42, 43, 44. The hot water supply controller 31 stores various set values such as a hot water supply temperature, and controls the start and end of the boiling operation.

  There are generally two types of boiling control in an electric water heater. One is full-boiling control in which the boiling operation is performed so that the entire amount of the hot water storage tank 11 is boiled up in the late-night time period (within the non-business hours in the commercial hot water supply system) where the electricity rate is low. The other is heating control for performing a boiling operation in order to prevent running out of hot water during daytime hours (business hours for commercial water heaters). In this embodiment, a commercial water heater will be described as an example.

  The water heater control unit 31 in the present embodiment has a clock function for measuring time, a calendar function for determining a date and a day of the week, a function for storing business hours (first time zone) for each day of the week, and the like. A day is divided into business hours and non-business hours (second time zone) to manage time.

  A remote controller 100 (operation unit) is connected to the water heater controller 31 so that they can communicate with each other. The operation of setting business hours for each day of the week can be performed using the remote controller 100. 2 to 4 are external views of remote controller 100 according to Embodiment 1 of the present invention. As shown in FIG. 2, the remote controller 100 includes a display unit 101, a date / time setting switch 111, a business hours setting switch 112, a selection switch 113, and a determination switch 114.

  In a normal state, the hot water supply temperature, the current time, and the like are displayed on the display unit 101 of the remote controller 100. When the date / time setting switch 111 is pressed, a date / time setting screen is displayed on the display unit 101 as shown in FIG. When the selection switch 113 is pressed in this state, the date displayed on the date setting screen changes. The current time and date managed by the clock function and calendar function of the water heater control unit 31 are rewritten by pressing the determination switch 114 when the displayed date and time is matched with the current accurate date and time.

  When the business hours setting switch 112 is pressed, a business hours setting screen is displayed on the display unit 101 as shown in FIG. Immediately after the display of the business hours setting screen, the mode for selecting the day of the week to change the setting is set. When the selection switch 113 is pressed in this day selection mode to select the day of the week and the decision switch 114 is pressed, the mode is shifted to a mode for setting the business hours of the selected day of the week. In this business hours setting mode, first the start time of business hours is set, and then the end time of business hours is set. In these settings, the displayed time changes when the selection switch 113 is pressed, and the time is determined by pressing the decision switch 114.

  Information on the business hours for each day of the week set by the above-described method is stored in the water heater controller 31. During the non-business hours, the water heater control unit 31 performs the whole amount boiling control. That is, the hot water supply controller 31 is not operated so that the entire amount in the hot water storage tank 11 is boiled at the start time of the next business hours based on the stored business hours information for each day of the week. A boiling operation (operation of the heat pump unit 200 and the heating circulation circuit 23) is performed during the time. More specifically, the water heater controller 31 first calculates the time required for boiling the entire amount based on the amount of remaining hot water or the amount of remaining heat in the hot water storage tank 11 and the heating rate of the heat pump unit 200. And the water heater control part 31 starts a boiling operation from the time which goes back only the time required for boiling up the whole quantity with respect to the start time of the next business hours. By such control, even if the business hours vary depending on the day of the week, the entire amount in the hot water storage tank 11 can be brought to a state of boiling just at the start time according to the business hours of each day of the week. .

  On the other hand, during business hours, the water heater control unit 31 performs boiling point control for preventing hot water from running out. That is, during business hours, the hot water supply controller 31 determines that the amount of remaining hot water in the hot water storage tank 11 equal to or higher than a predetermined temperature (for example, 45 ° C.) is less than a predetermined amount (hereinafter referred to as “minimum hot water storage amount”). First, a boiling operation is performed to increase the amount of hot water in the hot water storage tank 11. If the minimum amount of stored hot water is too large, energy consumption is wasted, and if it is too small, hot water may be insufficient. For this reason, it is desirable that the minimum hot water storage amount can be set from the remote controller 100 so that the user can select an optimal minimum hot water storage amount. Similarly, it is desirable that the amount of hot water at the completion of the reheating operation (hereinafter referred to as “the amount of reheated hot water”) can be set from the remote controller 100 as well.

  FIG. 5 is a diagram showing an example of the relationship between the amount of remaining hot water in hot water storage tank 11 and the boiling timing in Embodiment 1 of the present invention. In the example shown in FIG. 5, the minimum hot water storage amount is 300L, the boiling hot water amount is 400L, and the full hot water amount (capacity of the hot water storage tank 11) is 550L. At the start time of business hours, boiling of the entire amount is just completed, and the remaining hot water amount is 550 L which is the amount of full hot water. As hot water is used during business hours, the amount of hot water decreases. When the remaining hot water amount becomes less than the minimum hot water storage amount of 300 L, a boiling operation for increasing boiling is started, and the remaining hot water amount increases. Then, when the amount of remaining hot water reaches 400 L, which is the amount of hot water that has been heated up, the boiling operation for heating up is completed.

  As described above, according to the present embodiment, even if the business hours start time (hot water use start time) varies depending on the day of the week, the user does not change the setting each time, and the business hours of each day of the week. According to the start time, the entire amount in the hot water storage tank 11 can be brought into a state of boiling just at the start time of the business hours. For this reason, since the completion time of all-boiling is too early with respect to the business hours start time, and no heat loss occurs unnecessarily from the hot water storage tank 11, energy consumption can be suppressed. On the contrary, there is no case where hot water is insufficient due to the completion of boiling up in time for the start of business hours. In addition, since it is not necessary for the user to set the completion time for boiling the whole amount, the burden on the user is reduced and the operability is improved.

  In the present embodiment, the case where the heat pump unit 200 is used as the heating means for boiling the hot water in the hot water storage tank 11 has been described. However, the present invention uses other heating means such as a heater, gas, or solar power. It is also applicable to. In the present embodiment, the method for setting the date and business hours has been specifically described. However, the present invention is not limited to the described method, and other methods can be applied.

  Further, in the present embodiment, the case where the day is controlled by being divided into the first time zone (business hours) and the second time zone (non-business hours) before that is described as an example. In the present invention, one day may be divided into three or more time zones for control. In this embodiment, the case where the time zone division is set for each day of the week has been described as an example. However, in the present invention, the time zone division is set for each date or the time zone division is set for each period. It is also applicable to the case where The period can be set by the start date and end date, or by the number of weeks, months, and the like.

Embodiment 2. FIG.
Next, the second embodiment of the present invention will be described with reference to FIG. 6 and FIG. 7. The description will focus on the differences from the first embodiment described above, and the description of the same matters will be omitted. .

  FIG. 6 is a diagram illustrating an example of the relationship between the amount of remaining hot water in the hot water storage tank 11 and the boiling timing. As shown in FIG. 6, when the amount of remaining hot water at the start time of non-business hours is small and the non-business time is not set sufficiently long with respect to the heating speed of the heat pump unit 200, If the boiling operation is started from the start time, it may not be possible to complete the boiling up at the start time of business hours. In such a case, in the present invention, the boiling operation may be continued until the end of the non-business hours (that is, after the business hours are started), and the entire amount of the hot water storage tank 11 may be boiled.

  On the other hand, in Embodiment 2 of the present invention, the amount of remaining hot water at the start time of the non-business hours is small, and the non-business hours are not set sufficiently long with respect to the boiling rate of the heat pump unit 200. However, the following control is performed in order to ensure that all the boiling is completed at the start time of business hours. Prior to non-business hours (that is, during business hours), the water heater control unit 31 completes boiling up by the start time of the next business hours when the boiling operation is started from the non-business hours start time. Predict whether or not. This prediction is performed based on the amount of remaining hot water or remaining heat in the hot water storage tank 11 detected by the temperature sensors 41, 42, 43, and 44 and the length of non-business hours. That is, when the remaining amount of hot water in the hot water storage tank 11 or the amount of residual heat and the heating speed of the heat pump unit 200 are calculated, the time required for boiling the entire amount is calculated, and when the time exceeds the length of non-business hours If the boiling operation is started from the start time of the non-business hours, it is determined that the total amount of boiling is not completed by the start time of the next business hours. And when the hot water supply controller 31 determines that the boiling operation is started from the non-business hours start time and the boiling of the entire amount is not completed by the start time of the next business hours, the non-business hours start time The boiling operation starts from before.

  FIG. 7 is a diagram showing an example of the relationship between the amount of hot water in the hot water storage tank 11 and the boiling timing in Embodiment 2 of the present invention. In the example shown in FIG. 7, when the water heater control unit 31 starts the boiling operation from the start time of the non-business hours, it is determined that the boiling is not completed by the start time of the next business hours, and the non-business hours This is an example in the case where the boiling operation is started from the point A which is a time point before the start time.

  As shown in FIG. 7, the rate of increase in the amount of hot water in the hot water storage tank 11 between point A and the non-business hours start time (the slope of B in FIG. 7) is slower than during non-business hours. . This is because hot water is used during business hours and hot water is supplied from the hot water storage tank 11 to the outside. The slope of B in FIG. 7 can be predicted by subtracting the use speed of hot water in the hot water storage tank 11 by hot water supply from the boiling speed of the heat pump unit 200.

  When the water heater control unit 31 starts the boiling operation from the non-business hours start time, it is determined that the boiling of the entire amount is not completed by the start time of the next business hours, and the boiling operation is started from the business hours. In this case, it is desirable to control as follows. First, based on the history of the amount of remaining hot water in the hot water storage tank 11 during business hours, the hot water use speed in the hot water storage tank 11 due to hot water supply (the slope of C in FIG. 7) is calculated. Next, based on the calculated hot water usage rate and the boiling rate of the heat pump unit 200, the rate of increase in the amount of hot water in the hot water storage tank 11 when the boiling operation is started within business hours (in FIG. B slope) is predicted. Then, the boiling operation is started from the point A in FIG. 7, which is the intersection of B in FIG. 7 and C in FIG. By controlling in this way, it is possible to bring the entire amount in the hot water storage tank 11 into a state of boiling just at the start time of the next business hours.

  According to the second embodiment described above, even when the non-business hours are short, the boiling of the entire amount can be reliably completed at the next business hours start time. For this reason, the risk that hot water runs out can be reliably suppressed regardless of how the business hours are set.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG. 8. The description will focus on the differences from the above-described embodiment, and a description of the same matters will be omitted.

  In the present embodiment, the user can set in advance a regular holiday (no boiling-up execution day). The operation for setting a fixed holiday can be performed using the remote controller 100, and information on the set fixed holiday is stored in the water heater controller 31. The fixed holiday setting may be specified by date, it may be specified by day of the week, or it can be specified by week and day of the week, such as what day of the week. It may be.

  FIG. 8 is a diagram showing an example of the relationship between the amount of residual heat in the hot water storage tank 11 and the boiling timing when a regular holiday is set in the third embodiment of the present invention. When the regular holiday is set, the water heater control unit 31 omits the execution of the full amount heating control and the boiling increase control for the regular holiday. That is, as shown in FIG. 8, the hot water heater control unit 31, after the business hours on the day before a regular holiday ends, until the start of boiling all the amount in preparation for the business hours start time on the day after the regular holiday, Regardless of the decrease in the amount of residual heat, no boiling operation is performed.

  According to the third embodiment described above, since the hot water boiling is automatically stopped on a regular holiday without the user changing the setting every day, wasteful energy consumption is maintained while maintaining the operability of the user. It becomes possible to suppress.

Embodiment 4 FIG.
Next, the fourth embodiment of the present invention will be described with reference to FIG. 9. The description will focus on the differences from the above-described embodiment, and the description of the same matters will be omitted.

  In the present embodiment, as in the third embodiment described above, the user can set a fixed holiday in advance. Further, in the present embodiment, when the current day or the next day is set as a regular holiday, the fact is displayed on the display unit 101 (notification unit) of the remote controller 100 to alert the user. FIG. 9 is a flowchart of a routine executed by the water heater controller 31 when the current day or the next day is set as a regular holiday.

  In step S1, it is determined whether today is set as a regular holiday. If today is set as a regular holiday, the process proceeds to step S2, and if today is not set as a regular holiday, the process proceeds to step S5.

  In step S2, the display unit 101 of the remote controller 100 displays that today is set as a regular holiday and that the setting of today's regular holiday is canceled by pressing any switch on the remote controller 100. Proceed to step S3.

  In step S3, it is determined whether or not the switches 111 to 114 of the remote controller 100 are operated. If any switch is operated, the process proceeds to step S4. If none of the switches are operated, the process returns to step S1. Here, the reason for returning to step S1 is that if the date is changed while today is a fixed holiday, the determination in step S1 is required again. In step S4, today's fixed holiday setting is canceled and a message to that effect is displayed on the display unit 101 of the remote controller 100, and the process proceeds to step S5.

  In step S5, it is determined whether or not the next day is set as a regular holiday. If the next day is set as a regular holiday, the process proceeds to step S6. If the next day is not set as a regular holiday, the process ends. In step S6, the fact that the next day is set as a regular holiday is displayed on the display unit 101 of the remote controller 100, and then the process ends.

  According to the fourth embodiment described above, since it is possible to alert the user that the current day or the next day is set as a regular holiday, it is necessary to cancel the regular holiday setting for temporary business or the like. When there is, it can be surely prevented that the user forgets to cancel it. That is, the day before the day when the temporary operation was originally performed is displayed on the display unit 101 of the remote controller 100 to the effect that the next day is set as a fixed holiday. The next day's fixed holiday setting can be canceled without forgetting it. For this reason, it is possible to complete the boiling of all the hot water in the hot water storage tank 11 by the business start time on a special business day.

  Also, if you forget to cancel the fixed holiday setting by the previous day, you can quickly and easily cancel the fixed holiday setting by operating any switch on the remote control 100 on the day of the temporary business day Then, the boiling of the hot water storage tank 11 can be started. For this reason, it becomes possible to improve a user's operativity.

Embodiment 5 FIG.
Next, the fifth embodiment of the present invention will be described with reference to FIG. 10 to FIG. 12, but the description will focus on the differences from the above-described embodiment, and the description of the same matters will be omitted.

  In the present embodiment, in addition to the setting of business hours for each day of the week described in the first embodiment, the user can set business hours for holidays in advance. The operation of setting business hours for holidays can be performed using the remote controller 100, and information on the set business hours for holidays is stored in the water heater controller 31. FIG. 10 is an external view of remote controller 100 according to Embodiment 5 of the present invention. As shown in FIG. 10, the remote control 100 (operation unit) is provided with a holiday setting switch 115 (accepting means). When this holiday setting switch 115 is pressed, the water heater control unit 31 sets the start time and end time of business hours for the next day from the normal time set for each day of the week to the time set for holidays. Change to

  FIGS. 11 and 12 are diagrams each showing an example of the relationship between the amount of hot water in the hot water storage tank 11 and the boiling timing in Embodiment 5 of the present invention. Here, the business hours on weekdays are set from 11:00 to 19:00, and the business hours on holidays are set from 10:00 to 20:00. FIG. 11 shows a case where the holiday setting switch 115 is not pressed on the previous day. If the holiday setting switch 115 is not pushed on the previous day, as shown in FIG. 11, the boiling of the hot water storage tank 11 is completed at 11 o'clock which is set as the business hours start time on weekdays. The raising operation is executed. On the other hand, when the holiday setting switch 115 is pressed on the previous day, as shown in FIG. 12, the boiling of the hot water storage tank 11 is completed at 10 o'clock, which is set as the business hours start time for holidays. In addition, the boiling operation is performed.

  According to the fifth embodiment described above, the time of a time zone division (business hours, etc.) for a special day that occasionally appears, such as a public holiday, is set in advance, and becomes the day before that special day. In some cases, the time zone classification of the next day can be changed to the time for that special day with a simple operation. For this reason, it becomes possible to improve a user's operativity.

  In the above-described fifth embodiment, when the holiday setting switch 115 is pressed, the water heater control unit 31 changes the time zone classification of the next day to the time zone division for the holidays, but the next day The user may specify a specific date thereafter, and the time zone division of the designated date may be changed to the holiday time zone division.

DESCRIPTION OF SYMBOLS 10 Electric water heater main body 11 Hot water storage tank 21 Water supply pipe 22 Hot water supply pipe 23 Heating circulation circuit 31 Water heater control part 41,42,43,44 Temperature sensor 100 Remote control 101 Display part 111 Date setting switch 112 Business hour setting switch 113 Selection switch 114 Decision switch 115 Holiday setting switch 200 Heat pump unit

Claims (6)

A hot water storage tank,
Heating means that is driven by electricity and performs a boiling operation of boiling hot water in the hot water storage tank;
A remaining hot water amount detecting means for detecting a remaining hot water amount or a remaining heat amount in the hot water storage tank;
A time zone dividing means for managing the time by dividing at least one day into a first time zone and a second time zone before the first time zone;
In the first time zone, when the detected amount of remaining hot water or the amount of remaining heat becomes equal to or less than a predetermined value, the boiling increase control is performed to increase the amount of hot water in the hot water storage tank by performing a boiling operation. Means,
A total amount boiling control means for performing full amount boiling control for performing a boiling operation so that all the hot water in the hot water storage tank is boiled in the second time zone;
A time zone division setting unit that allows a user to set in advance a time for dividing the first time zone and the second time zone for each schedule such as date, day of the week, or period;
An electric water heater characterized by comprising. Prior to the second time zone, the boiling operation was started from the start time of the second time zone based on the detection result of the remaining hot water amount detecting means and the length of the second time zone. A predicting means for predicting whether or not boiling of the hot water storage tank is completed by the start time of the first time zone,
The total amount boiling control means starts boiling operation before the start time of the second time zone when the prediction result of the prediction means is negative. Electric water heater. A heating non-execution date setting means that allows the user to set a boiling non-execution date in advance,
3. The electric water heater according to claim 1, wherein execution of the total amount boiling control and the boiling increase control is omitted on the set boiling non-execution date.   4. The electric water heater according to claim 3, further comprising a notifying unit for notifying that when the current day or the next day is set as the non-running day. An operation unit having a plurality of switches;
When the current day is set as the non-executable boiling date, a release unit that cancels the setting of the non-performing date of the current day when any of the plurality of switches is operated,
The electric water heater according to claim 3 or 4, further comprising: Separate from the time set by the time zone division setting means, second time zone division setting means that allows a user to set in advance a time for dividing the first time zone and the second time zone. When,
The first time zone and the second time zone of the specified date on or after the next day are set by the second time zone classification setting means from the time set by the time zone classification setting means. An operation unit having a receiving means for receiving an instruction to change to a set time;
The electric water heater according to any one of claims 1 to 5, further comprising:

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