JPH05106915A - Electric hot water maker - Google Patents

Abstract

PURPOSE:To reduce the space required for installation and, at the same time, finish boiling up in the last half of the time of midnight electric cost time zone by constituting a hot water storage tank of a plurality of tanks which are arranged in series and each of which has a heat generating body on the lower section. CONSTITUTION:A first hot water storage tank 44 into which the supply water flows directly and a second hot water storage tank 45 which has a hot water drawing port in the upper section are provided, and at the lower sections of the tanks 44, 45 a first and second heat generating bodies 46, 47 are respectively installed. The tanks 44, 45 are provided respectively with a first and second hot water temperature respectively with a first and second hot water temperature measuring means 48, 49 for measuring stored hot water temperature. Results of detection of those temperature measuring means 48, 49 and set temperature by a hot water temperature setting means 4 are given to a calculator 5, and the ON/OFF of electric current supply to respective heat generating bodies 46, 47 is controlled through a heat generation body controller 50. In this control, the boiling of the hot water is controlled to come in the last half of midnight electric power cost time zone according to the temperature of the supply water to the first hot water storage tank 44, With this arrangement the heat loss due to heat radiation is reduced and the supply of high temperature hot water is feasible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric water heater, and more particularly to boiling control of an electric water heater having a plurality of hot water storage tanks.

[0002]

2. Description of the Related Art FIG. 12 is an overall configuration diagram of a conventional boiling control device for an electric water heater. FIG. 13 is a circuit configuration diagram of its main part. In FIG. 12, reference numeral 1 denotes a hot water storage tank, which has a cylindrical shape because it has a high pressure during boiling. A heating element 2 is attached to the lower part of the hot water storage tank. The capacity of this heating element is determined so as to boil up to a constant temperature in the midnight power supply time (8 hours). For example, 3
70 liter water heater, water temperature 10 ℃, boiling temperature 8
If the boiling efficiency is 0.95, and the heating value per 1 kwH is 860 at 5 ° C, the capacity P of the heating element is

[0003]

[Equation 1]

[0004] In addition, the electricity rate is the same from 3.5kW to 4.4kW in the basic rate of midnight power, and is 4.5
Since it increases from kW or more, the maximum capacity of 4.4 kW in the zone with the same charge is generally adopted.

Reference numeral 3 is a hot water temperature measuring means for measuring the feed water temperature and the boiling water temperature, and 4 is a hot water temperature setting means for setting the boiling water temperature. Reference numeral 5 is a calculation means for calculating the energization start time based on the boiling water temperature set by the hot water temperature setting means 4 and the measured hot water temperature of the hot water temperature measuring means 3. 6 is a heating element control means,
ON / OFF of the heating element 2 is controlled based on the calculation result of the calculation means 5 and the measured hot water temperature of the hot water temperature measuring means. Reference numeral 7 is a power source for late-night power, and 8 is a late-night power detection means for detecting the presence or absence of supply of late-night power. Reference numeral 9 is a faucet for taking out boiling water.

In FIG. 13, reference numeral 11 denotes a microcomputer in the control circuit, which includes a CPU 12, a clock means 10, a memory 13, an input circuit 14, an output circuit 15, and A /
It is formed of a D converter 16 and an analog multiplexer 17. Reference numeral 18 denotes a heating element control circuit, which corresponds to the heating element control means 6 in FIG. 12, and includes resistors 19, 20 and a transistor 2.
1, relays 22 and 23 and diodes 24 and 25.

One end of the coil of the relay 22 is a positive terminal +
Connected to V and the other end via transistor 21 to GND
Is connected to the terminal, the base of the transistor 21 and the resistor 19
It is connected to the output circuit 15 via. The resistor 20 is connected between the base and the emitter of the transistor 21. One end of the normally-open contact of the relay 22 is connected to the positive electrode terminal + Va, and the other end is connected to the GND terminal via the coil of the relay 23. Diodes 24 and 25 are connected to both ends of each coil of the relay 22 and the relay 23.
The contacts of the relay 23 are connected in series to the heating element 2 and the midnight power supply 7.

The resistor 26 is connected in series with the hot water temperature setting means 4 composed of a variable resistor, and both ends of the resistor 26 are positive terminal + V and GND.
It is connected to the terminal. Further, the connection between the resistor 26 and the hot water temperature setting means 4 is connected to the analog multiplexer 17. The resistor 27 is a temperature detecting means 3 including a thermistor.
Are connected in series, and both ends thereof are connected to the positive electrode terminal + V and the GND terminal. Further, the resistor 27 and the temperature detecting means 3
The connection part with is connected to the analog multiplexer 17.

Reference numeral 28 denotes a midnight power detecting circuit for detecting the midnight power, which corresponds to the midnight power detecting means 8 in FIG. 12, and includes resistors 29, 30, a diode 31, and a photocoupler 3.
It consists of 2. The light emitting side of the photocoupler 32 has a resistor 2
A photo diode 32 is connected in series to the power source 7 via a diode 9, and a diode 31 is connected in parallel to both ends of the photo coupler 32 on the light emitting side. One end on the light receiving side of the photocoupler 32 is connected to the positive electrode terminal + V via the resistor 30 and the other end is connected to the GND terminal, and the resistor 3 is connected.
The connection between 0 and the light receiving side of the photocoupler 32 is connected to the input circuit 14 in the microcomputer 11.

Next, the operation of the conventional boiling control device for an electric water heater will be described with reference to FIG. FIG. 14 is a flowchart of the heating element control stored in the memory 13 of the microcomputer 11. First, the control power is turned on, and at the same time, the presence / absence of a midnight power supply is detected (step 33). If power is supplied at midnight, the clock means 10
Then, the timer is started, the feed water temperature is measured in step 35, and the setting of the boiling temperature in the hot water storage tank is read in step 36. Next, in step 37, the net energization time required to boil from the water supply water temperature to the set temperature is calculated, and in step 38, from which time in the midnight power supply time zone the energization is started.

The supply water temperature is Tw (° C.) and the boiling temperature is T
(° C) and the capacity of the heating element 2 is P (kW), the net energizing time H (hr) is

[0012]

[Equation 2]

Is calculated by The midnight power supply time is generally 8 hours from 23:00 to 7:00 the next morning, and the energization start time Hp is Hp = 8−H. By controlling the boiling time in this way, the start time of energization changes according to the supply water temperature and the hot water temperature setting temperature, and boiling is performed during the off-peak time period, which is the original feature of the midnight power system. Since the boiling is done in the latter half of the midnight power hours, there is a feature that the loss due to heat dissipation is reduced.

Next, the clock means 10 in the microcomputer 11 determines whether or not the energization start time has come (step 39), and when the energization start time comes, the step 4
At 0, energization of the heating element 2 is started. Then step 4
1. Measure the hot water temperature in the hot water storage tank (measured value is Tm (° C)
Then, the set value T (° C.) of the boiling temperature is compared with the measured value Tm (° C.) of the hot water temperature (step 42), and when Tm reaches T, the heating element 2 is turned off (step 43), The control for one day is completed, and the next day is repeated from step 33.

[0015]

As described above, since the conventional electric water heater is configured to control boiling for a large-capacity hot water storage tank, it is installed in a cylindrical water heater. In this case, a space of about 1 m ² (1 m × 1 m) is required, and there is a problem that it cannot be installed in a place without this space.

The present invention has been made in order to solve the above problems, and the shape of the water heater main body is made thin so that it can be installed even in a space that cannot be installed in the cylindrical shape of a single hot water storage tank, and the boiling water is raised. It is an object of the present invention to provide a water heater capable of controlling the boiling time of the power supply so that it is in the latter half of the midnight power time zone and reducing heat loss until the supply of the midnight power is completed.

[0017]

An electric water heater according to a first aspect of the present invention detects a plurality of hot water storage tanks which are connected in series and each of which has a heating element at the bottom thereof, and boiling water temperature and feed water temperature. Based on the output of the temperature detecting means, the hot water temperature setting means for setting the boiling water temperature, the power source detecting means for detecting the presence or absence of the power source of the midnight power, the temperature detecting means, the hot water temperature setting means and the power source detecting means. It is provided with a calculation means for calculating a power supply start time for moving the power supply to the latter half of the midnight power time zone, and a heating element control means for controlling the power supply to the heating element based on the output of the calculation means. ..

An electric water heater according to a second aspect of the present invention is the electric water heater according to the first aspect of the present invention, in which an upper heating element is provided above a hot water storage tank near a hot water inlet of a plurality of hot water storage tanks, and an energization start time is calculated by a calculation means. Based on the calculation result, first, the upper heating element is energized, and then the lower heating element of the hot water storage tank near the hot water inlet and the heating element of the hot water supply side hot water storage tank are sequentially switched to be energized.

In the electric water heater according to the third aspect of the present invention, in the second aspect of the present invention, when the temperature of the hot water in the portion where the boiling has been completed has dropped more than a certain temperature, the heating element is energized during the boiling. Is stopped and the heating element in the part where the hot water temperature has dropped is re-energized.

The electric water heater according to a fourth aspect of the present invention is the electric water heater according to the first aspect of the present invention, which is provided with additional heating setting means for setting additional heating, and has a plurality of hot water storage tanks that generate heat from the upper portion of the hot water storage tank near the tap. When a body is provided and additional heating is set within the power supply time, heating by the upper heating element is prioritized.

[0021]

In the first aspect of the present invention, the hot water storage tank is composed of a plurality of tanks which are connected in series and each of which has a heating element at the bottom thereof. The depth is thinner than that of a hot water storage tank.

In the second aspect of the invention, the upper heating element is provided above the hot water storage tank near the hot water intake port of the plurality of hot water storage tanks, the energization start time is calculated by the calculation means, and the upper heat generation is performed based on the calculation result. Since the body is energized, in addition to the effect of the first aspect, the temperature of the hot water near the hot water sampling port reaches the set temperature in a short time after the time when the power is turned on.

In the third aspect of the invention, when the hot water temperature at the portion where boiling has been completed has fallen below a certain temperature,
Since power supply to the heating element during boiling is stopped and power is supplied again to the heating element in the portion where the hot water temperature has dropped, in addition to the function of the second aspect of the invention, a drop in hot water temperature above a certain temperature is prevented.

In the fourth aspect of the invention, the additional heating setting means is provided, and the upper heating element is provided above the hot water storage tank near the hot water inlet. When the additional heating is set within the power supply time, heating by the upper heating element is performed. If you want to use the hot water urgently, you can set the additional heating so that the hot water temperature near the hot water inlet reaches the set temperature in a short time.

[0025]

【Example】

Example 1. An embodiment of the present invention will be described below.
FIG. 1 is a block diagram showing a configuration of a water heater shown in the case where a plurality of tanks is two according to an embodiment of the present invention.
In the figure, the same reference numerals as those in FIG. 12 indicate the same or corresponding parts, 44 is a first hot water storage tank into which water is directly supplied, 45 is connected in series with the upper part of the first hot water storage tank 44, and has a hot water inlet in the upper part A second hot water storage tank, 46 is a first heating element attached to the lower portion of the first hot water storage tank 44, and 47 is a second heating element attached to the lower portion of the second hot water storage tank 45. As in the case of the conventional example, when the total capacity of the hot water storage tank is 370 l and the capacity of the heating element is 4.4 kW, the capacity of the first and second hot water storage tanks is 185 l (= 370 /
2), and the capacities of the first heating element 46 and the second heating element 47 are 2.2 kW (= 4.4 / 2). For example, if the height of the hot water storage tank is 370 l and the hot water storage tank capacity is 370 l and the hot water storage tank is composed of two hot water storage tanks, the diameter can be improved by approximately 70%, that is, the hot water storage tank can be thinned by approximately 30%.

Reference numeral 48 is a first hot water temperature measuring means for measuring the supplied water temperature and hot water temperature, 49 is a second hot water temperature measuring means for measuring the hot water temperature of the second hot water storage tank, and 50 is a computing means 5 and the first hot water temperature measuring means. The heating element control means controls ON / OFF of the first heating element 46 and the second heating element 47 based on the outputs of the hot water temperature measuring means 48 and the second hot water temperature measuring means 49.

FIG. 2 is a circuit diagram showing a circuit structure of a main part. The same reference numerals as those in FIGS. 12 and 13 denote the same or corresponding parts, 18 is a first heating element control circuit, and 51 is a second.
The second heating element control circuit for controlling ON / OFF of the heating element is the same as the configuration of the first heating element control circuit 18. Reference numerals 52 and 53 are resistors, which are connected in series to the hot water temperature measuring means 48 and 49, respectively, and the connecting portions thereof are the microcomputer 1
It is connected to the analog multiplexer 17 in 1.
The other ends of the resistors 52 and 53 are connected to the positive terminal + V. The other ends of the hot water temperature measuring means 48, 49 are connected to the GND terminal.

Next, the operation will be described. FIG. 3 is a flowchart showing the operation of the water heater of the present invention, and the same reference numerals as in FIG. 14 indicate the same or corresponding parts. When the switch (not shown) is turned on, the control circuit operates, and in step 33, it is detected whether or not the midnight power is supplied. When the energization start time is reached in step 39, energization of the first and second heating elements is started in step 54, and then the hot water temperature measuring means 48 measures the hot water temperature in step 55 on the first hot water storage tank side. .. It is determined whether this measured hot water temperature Tm1 is higher than the hot water temperature T read in step 36 (step 5
6) When the temperature becomes higher, the power supply to the first heating element 46 is stopped in step 57. Also, in step 56, the measured hot water temperature Tm
If 1 is less than the set hot water temperature T, the process is repeated from step 55.

Similar to the first hot water storage tank 44, step 5
When power supply to the second heating element is started in step 4, step 5
At 8, the hot water temperature measuring means 49 measures the hot water temperature. It is determined whether or not the measured hot water temperature Tm1 is higher than the hot water temperature T read in step 36 (step 59), and if it becomes higher, the power supply to the second heating element 47 is stopped in step 60. If the measured hot water temperature Tm2 is equal to or lower than the set hot water temperature T in step 59, the process is repeated from step 58.

The hot water heater in this embodiment is constructed as described above, and since the hot water storage tank, which was conventionally constituted by one hot water storage tank, is constituted by a plurality of hot water storage tanks, the installation space can be made thin and at the bottom of each hot water storage tank. Since the total capacity of the attached heating elements was the same as the conventional example, the power distribution equipment for the water heater was also the same, and the boiling was set to the latter half of the midnight power time zone according to the temperature of the water supplied to the first hot water storage tank. The feature is that loss due to heat dissipation can be reduced.

Example 2. 4, 5 and 6 are views showing a second embodiment of the present invention. In this embodiment, as shown in FIG. 4, a third heating element 61 attached to the upper part of the second hot water storage tank is provided. The third hot water temperature measuring means 62 is provided.
FIG. 5 is a circuit diagram showing a circuit configuration of a main part. 63 is a resistor, which is connected in series with the third hot water temperature measuring means 62, and the connecting part is connected to the analog multiplexer 17 in the microcomputer 11. There is. The other end of the resistor 63 is connected to the positive terminal + V, and the other end of the third hot water temperature measuring means 62 is G
It is connected to the ND terminal. 64 is the third heating element 61
The control circuit controls the supply of power to the control circuit and has the same configuration as 18. The capacities of the first and second heating elements and the capacity of the third heating element in the present invention are 4.4 kW, which is the same as in the conventional example.

Next, the operation of the second embodiment will be described. FIG. 6 is a flowchart showing the operation of the water heater of the present invention. When the switch (not shown) is turned on, the control circuit operates, and in step 33, it is detected whether or not the midnight power is supplied. When the energization start time is reached in step 39, energization to the third heating element is started in step 65,
Next, at step 66, the third hot water temperature measuring means 62 measures the hot water temperature Tm3. Next, it is determined whether the measured hot water temperature Tm3 is higher than the set temperature T read in step 36 (step 67).
Then, the third heating element is turned off and the second heating element is turned on (step 69).

Next, the second hot water temperature measuring means 49 measures the hot water temperature Tm2 (step 70), and it is judged whether or not the hot water temperature Tm2 becomes higher than the set temperature T read in step 36 (step 71). ), When the temperature becomes higher, the second heating element is turned off in step 72 and the first heating element is turned on (step 73). Next, the first hot water temperature measuring means 48 measures the hot water temperature Tm1 (step 74).
It is determined whether or not m1 is higher than the set temperature T read in step 36 (step 75), and when it becomes higher, the first heating element is turned off in step 76. Step 7
When 6 is completed, the boiling control on the current day is stopped, and the boiling control on the next day is repeated from step 33.

In the second embodiment, as described above, each heating element has a capacity of 4.4 kW, which is the same as that of the conventional example, and the heating is performed from the third heating element, then the second heating element. In order to boil with the heating element of No. 1 and finally with the first heating element, and to boil from the upper part of the second hot water storage tank 45, for example, the mounting position of the third heating element is set to the second hot water storage tank. Assuming 50l from the top of the tank, the time t1 for boiling 50l is

[0035]

[Equation 3]

In contrast to the conventional example, which takes 8 hours, the present invention takes about 1 hour, which is a characteristic that hot water can be taken in a short time.

Example 3. FIG. 7 is a flow chart showing the operation of the third embodiment of the present invention. The overall configuration is shown in Figure 4,
The circuit diagram of the main part is the same as that of FIG. In FIG. 7, reference numeral 77 denotes a step for determining whether or not the measured temperature Tm3 of the third hot water temperature measuring means 62 has dropped from the set temperature T of the hot water temperature setting means 4 by a constant temperature, for example, 10 ° C. or more. Then, the power supply to the second heating element attached to the lower portion of the second hot water storage tank 45 is stopped (step 72), and step 65 is repeated. If the third hot water temperature measuring means 62 does not fall below the set temperature T by 10 ° C. or more in step 77, the process proceeds to step 71.

Reference numeral 78 indicates that the measured temperature Tm2 of the second hot water temperature measuring means 49 is a constant temperature than the set temperature T of the hot water temperature setting means 4,
For example, in the step of determining whether or not the temperature has dropped by 10 ° C. or more, if the temperature has dropped, the power supply to the first heating element attached to the lower portion of the first hot water storage tank 44 is stopped (step 76), and step 69 Repeat from. If the second hot water temperature measuring means 49 has not dropped from the set temperature T by 10 ° C. or more in step 78, the process proceeds to step 77a. Step 77
At a, it is determined whether or not Tm3 has dropped from T by a constant temperature (10 ° C.) or more. If it has fallen, energization to the first heating element is stopped and the process is repeated from step 65. If it has not descended, move to step 75.

In the third embodiment, boiling is started from the upper part of the second hot water storage tank 45 near the hot water inlet, and then the lower part of
The water is boiled to the first hot water storage tank to obtain the hot water at the set temperature in a short time, and even if there is hot water taken during the boiling and the boiled water is used Since the hot water temperature measuring means 62 and 49 measure the hot water and boil them again when the temperature drops by a constant temperature, the hot water temperature of the hot water temperature T set within the midnight power supply time zone can be reliably obtained. is there.

Example 4. 8, 9 and 10 are diagrams showing a fourth embodiment of the present invention. In this embodiment, as shown in FIG. 8, the third heating element 61 is arbitrarily prioritized to be set for boiling. The additional heating setting means 79 that can be used is provided. FIG. 9 is a circuit diagram of the main part of the fourth embodiment, in which 80 is a switch corresponding to the additional heating setting means 79, and 81 is a resistance. Each of them is connected in series, and the connecting portion is connected to the input circuit 14 in the microcomputer 11. The other end of the resistor 81 is connected to the positive electrode terminal + V, and the other end of the switch 80 is connected to the GND terminal.

FIG. 10 is a flow chart showing the operation of the fourth embodiment of the present invention. The case where the capacities of the first and second heating elements are set to 2.2 kW as in the first embodiment will be described. In FIG. 10, reference numeral 82 is a step for determining whether or not the switch 80 corresponding to the additional heating setting means 79 is set. If additional heating is set in step 82, the boiling by the third heating element is preferentially performed, and then the boiling by the first and second heating elements is performed. If additional heating is set during boiling in the first and second heating elements, stop the first and second boiling and preferentially perform boiling in the third heating element. ing.

Example 5. FIG. 11 is a flow chart showing the operation of the fifth embodiment of the present invention. As in the second embodiment, the capacities of the first and second heating elements are set to 4.4 kW, the boiling is performed from the third heating element, and the second and first heating elements are boiled in order. If additional heating is set during boiling, the power supply to the heating element during boiling is stopped, and the third
Repeat from the boiling by the heating element. In the fourth and fifth embodiments, when the hot water is to be used urgently, the boiling of the upper part of the second tank is prioritized by the third heating element only when the additional heating is set. There is a feature that can be used.

[0043]

According to the first aspect of the present invention, since the hot water storage tank is composed of a plurality of tanks connected in series and each provided with a heating element at the bottom, when the hot water storage tanks have the same height, 1 The depth is thinner than in the case of a book hot water storage tank, and it can be installed in a space where a single hot water storage tank cannot be installed in a cylindrical shape, and boiling control can be performed so that the energization time is in the latter half of the midnight power time zone.

In the second aspect of the invention, the upper heating element is provided above the hot water storage tank near the hot water intake port of the plurality of hot water storage tanks, the energization start time is calculated by the calculating means, and the upper heat generation is performed based on the calculation result. Since the body is energized, in addition to the effect of the first invention, hot water can be taken in a short time after the energization start time.

In the third aspect of the invention, when there is a decrease in the hot water temperature of a certain temperature or more,
Since power supply to the heating element during boiling is stopped and power is supplied again to the heating element in the portion where the temperature has dropped, in addition to the effect of the second invention, an extreme drop in the constant temperature of the hot water is prevented and set. Hot water at the boiling temperature can be reliably obtained.

In the fourth aspect of the present invention, when the additional heating setting means is provided and the upper heating element is provided in the upper part of the hot water storage tank near the hot water inlet, and when additional heating is set within the power supply time, the upper heating element is used. First, because heating is prioritized
In addition to the effects of the invention, when hot water is used urgently, if additional heating is set, hot water at the set temperature can be used in a short time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a main part of the embodiment shown in FIG.

FIG. 3 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

5 is a circuit diagram showing a circuit configuration of a main part of the embodiment shown in FIG.

6 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 7 is a flowchart showing the operation of the third exemplary embodiment of the present invention.

FIG. 8 is a block diagram showing a fourth embodiment of the present invention.

9 is a circuit diagram showing a circuit configuration of a main part of the embodiment shown in FIG.

10 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 11 is a flowchart showing the operation of the fifth exemplary embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a conventional electric water heater.

FIG. 13 is a circuit diagram showing a circuit configuration of a main part of a conventional electric water heater.

FIG. 14 is a flowchart showing the operation of a conventional electric water heater.

[Explanation of symbols]

 4 hot water temperature setting means 5 computing means 7 midnight electric power source 8 power supply detecting means 44 first hot water storage tank 45 second hot water storage tank 46 first heating element 47 second heating element 48 first hot water temperature measuring means 49 2 hot water temperature measuring means 50 heating element control means 61 third heating element 62 third hot water temperature measuring means 79 additional heating setting means

Claims (4)

[Claims] 1. A plurality of hot water storage tanks, which are connected in series and each provided with a heating element at the bottom, temperature detecting means for detecting boiling water temperature and feed water temperature, and hot water temperature setting means for setting boiling water temperature. A power supply detecting means for detecting the presence / absence of a power source for the midnight power, and a power supply start time for moving the power supply to the latter half of the midnight power time zone based on the outputs of the temperature detecting means, the hot water temperature setting means and the power supply detecting means An electric water heater, comprising: a calculation unit that calculates a value and a heating element control unit that controls energization of the heating element based on the output of the calculation unit. 2. An upper heating element is provided above a hot water storage tank near a hot water inlet of a plurality of hot water storage tanks, an energization start time is calculated by a calculation means, and the upper heating element is first set on the basis of the calculation result. 2. The electric water heater according to claim 1, wherein electricity is applied, and then the heating element in the lower part of the hot water storage tank near the hot water inlet and the heating element in the hot water storage tank on the upstream side of water supply are sequentially switched to be energized. 3. When the temperature of the hot water in the portion where boiling has been completed has dropped below a certain temperature, power supply to the heating element is stopped during boiling, and heat is generated in the portion where there is a decrease in hot water temperature. The electric water heater according to claim 2, wherein the body is re-energized. 4. An additional heating setting means for setting additional heating is provided, and an upper heating element is provided above the hot water storage tank near the hot water inlet of the plurality of hot water storage tanks, and the additional heating is performed within the power supply time. When set, the heating by the upper heating element is prioritized.
The described electric water heater.