JP2001108304A - Electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve a problem in a conventional electric water heater that boiling up is effected during a daytime band to a temperature same as the boil-up temperature in a nighttime band even when remaining hot-water in a hot-water storage tank is enough in the quantity of the same until the nighttime band is started whereby a charge for electric power becomes expensive. SOLUTION: The energization of a heating means is stopped from the beginning of a daytime band until the beginning of a nighttime band or when 10 hours have elapsed after the beginning of the daytime band while the boil-up temperature in the daytime band is lowered to 70 deg.C, lower than the boil-up temperature of 90 deg.C in the nighttime band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of boiling water in an electric water heater.

[0002]

2. Description of the Related Art FIG. 8 is a system configuration diagram of a conventional electric water heater, FIG. 9 is a block diagram thereof, and FIG. 10 is a flowchart of the boiling control. In FIG. 8, reference numeral 1 denotes an electric water heater main body, which includes a hot water storage tank 2, a pressure reducing valve 3 for keeping the pressure of the hot water storage tank 2 constant, and a relief valve 4. A water supply port is provided at a lower part of the hot water storage tank 2, and a water supply port is provided at an upper part. Hot water from the water supply port is mixed with water to be used at an appropriate temperature. A heating element 5 for heating water in the hot water storage tank 2 and a temperature sensor 6 for detecting a boiling temperature of hot water in the hot water storage tank 2 and a supply water temperature are attached to a lower portion of the hot water storage tank 2. I have. The temperature sensor 6 can detect the boiling temperature and the supply water temperature, and can detect the amount of remaining hot water in the hot water storage tank 2 from the detected temperatures. Reference numeral 7 denotes a control unit for detecting a power supply time period (daytime time period and night time time period) and controlling boiling of hot water in the hot water storage tank 2, and 8 is an operation unit for setting a boiling temperature and the like. As shown in FIG. 9, the control unit 7 controls energization to the heating element 5 based on a detection value of the temperature sensor 6 and an input value from the operation unit 8.

[0003] Next, regarding the operation of the conventional electric water heater,
This will be described with reference to the flowchart of FIG. When the energization control is started (S1), the control unit 7 detects an energization time zone (S2). Here, the energizing time zone is a daytime zone and a nighttime zone, the daytime zone is from 7:00 am to 11:00 pm, and the night time zone is from 11:00 pm to 7:00 in the next morning. If it is not the daytime zone (S3), that is, if it is the nighttime zone,
The heating element 5 is energized (S6), and when the temperature sensor 6 detects that the hot water in the hot water storage tank 2 has reached the boiling temperature T ° C. (90 ° C.) (S12), energization of the heating element 5 is performed. It stops (S9) and ends the energization control (S10).

In the daytime time zone (S3), the temperature sensor 6 detects the temperature of the mounting portion of the temperature sensor 6 of the hot water storage tank 2, that is, the presence or absence of remaining hot water (S4). When detecting a low temperature equal to or less than the value, the control unit 7 determines that the remaining hot water amount has become equal to or less than the predetermined amount (S5), and
To the power supply (S6). When the temperature sensor 6 detects that the temperature has risen to T ° C., the power supply is stopped (S9),
The energization control ends (S10). When it is determined that the remaining hot water amount is equal to or more than the predetermined amount (S5), the process returns to the detection of the energizing time zone (S2) without performing boiling.

[0005]

The conventional electric water heater is
As described above, in the daytime, when it is determined from the detection value of the temperature sensor 6 that the amount of remaining hot water has become smaller than the temperature sensor 6 mounting portion, boiling is immediately started to prevent running out of hot water in the hot water storage tank 2. So that the temperature sensor 6 is
If it is installed in the lower part, after the evening when hot water is used a lot in the day, the low temperature is immediately detected and the water is frequently heated. In addition, it was heated to the same temperature as the temperature at night. However, even after the evening when hot water is consumed,
It is often sufficient to use the remaining hot water in the tank until the start of the night hours, and it is not always necessary to fill the tank with hot water. In other words, conventional electric water heaters unnecessarily boil a lot during the daytime hours when the electricity bill is high, and hardly boil during the night hours when the electricity bill is low.
There was a problem that the electricity bill was high. Also, in the summer season when the amount of hot water used is small, it is similarly heated,
There was a problem that the electricity bill was high.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and controls the power supply to the heating element during the daytime when the electricity bill is high so that the electricity bill is low and the hot water runs out. It is an object of the present invention to provide an electric water heater that can prevent the occurrence of water.

[0007]

An electric water heater according to the present invention comprises a hot water storage tank, heating means for heating water in the hot water storage tank, and a temperature sensor for detecting a boiling temperature, a remaining hot water amount, and a feed water temperature. A power supply time zone detecting means for discriminating between a daytime time zone and a night time zone, for a predetermined time until the start of the night time zone in the daytime time zone, while limiting the power supply to the heating means, and in the daytime time zone. The boiling temperature is set lower than the boiling temperature in the night time zone.

[0008] Further, a hot water storage tank, a heating means for heating water in the hot water storage tank, a temperature sensor for detecting a boiling temperature, a remaining hot water amount, and a supply water temperature, and a power supply for discriminating between daytime and nighttime hours. A time zone detecting means, for limiting a power supply to the heating means for a predetermined time until the start of a night time zone in a daytime time zone, and changing the predetermined time in accordance with the temperature of the water supply water. .

Further, the boiling temperature in the daytime period is changed according to the temperature of the water supply water.

[0010] Further, an operation unit for setting a time for limiting the energization of the heating means is provided.

Further, the electric water heater according to the present invention is provided with a plurality of temperature sensors for detecting the amount of remaining hot water, and changes the time for restricting energization to the heating means in accordance with the amount of remaining hot water and the temperature of the supply water. It is.

Further, a plurality of temperature sensors for detecting the remaining hot water amount and a storage means for storing the past remaining hot water amount are provided, and a time for limiting the energization to the heating means is changed according to the past remaining hot water amount and the temperature of the supply water. It is something to do.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1, 8, and 9. FIG. FIG. 1 is a flowchart of the boiling control of the electric water heater in the first embodiment. 8 and 9
Has been described as a system configuration diagram and a block diagram of a conventional electric water heater, but since the configuration of the electric water heater in the first embodiment is the same, the description will be omitted, and only the boiling control will be described.

When the energization control is started (S1), the control unit 7
Detects the energization time zone (S2). Here, the energization time zone is a daytime zone and a night time zone, and the daytime zone is 7
From time to 11:00 p.m., the night time zone is from 11:00 p.m. to the next morning 7
Until time. If it is not the daytime zone, that is, if it is the nighttime zone (S3), the power supply to the heating element 5 is started (S1).
1) When the temperature sensor 6 detects that the hot water in the hot water storage tank 2 has reached the boiling temperature T ° C (for example, 90 ° C) (S12), the power supply to the heating element 5 is stopped (S9), and the power supply control is performed. Is completed (S10).

If it is during the daytime (S3), the temperature sensor 6 detects the temperature of the mounting portion of the temperature sensor 6 of the hot water storage tank 2, that is, the presence or absence of remaining hot water (S4). When a low temperature equal to or lower than the predetermined value is detected, the controller 7 determines that the remaining hot water amount has become equal to or lower than the predetermined amount (S5), and starts energization of the heating element 5 (S6).

Next, it is determined whether or not a predetermined time (for example, 10 hours) has elapsed since the start of the daytime period, that is, whether or not 5:00 in the evening has passed (S7). If it is determined that 10 hours have elapsed since the start of the daytime, the power supply is stopped regardless of the boiling temperature (S9), and the power supply control is terminated (S10). If 10 hours have not elapsed, the boiling is continued and the temperature sensor 6 detects T1 ° C. (for example, 7 ° C.).
When it is detected that the heating element has been heated to 0 ° C.) (S8), the power supply to the heating element 5 is stopped (S9), and the power supply control is terminated (S10). Here, the boiling temperature T1 is set lower than the boiling temperature T in the night time zone. If 10 hours have elapsed since the start of the daytime during boiling (S7), the power supply is stopped regardless of the boiling temperature (S7).
9) The energization control ends (S10).

As described above, according to the electric water heater in the first embodiment, even in the daytime, the heating element is used for 6 hours from 5:00 in the evening to 11:00 when the nighttime starts. When the power is not supplied to the heater 5 and the heating is performed during the daytime, the heating temperature is controlled to be lower than the boiling temperature during the nighttime. It reduces electricity costs while preventing running out of hot water.

As a means for heating the hot water in the hot water storage tank 2, a heat pump type heat exchanger may be used instead of the heating element 5. Further, in the above description, the boiling temperature, the supply water temperature, and the remaining hot water amount are detected by one temperature sensor 6, but separate temperature sensors may be provided.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS. 2, 8, and 9. FIG. FIG.
Fig. 4 is a flowchart of the control of boiling the electric water heater in the second embodiment. 8 and 9 have been described as a system configuration diagram and a block diagram of a conventional electric water heater, but since the configuration of the electric water heater in the second embodiment is the same, the description is omitted, and the boiling control is omitted. Will be described only.

When the energization control is started (S1), the control unit 7
Detects the energization time zone (S2). If it is not the daytime zone, that is, if it is the nighttime zone (S3), the heating element 5 is energized (S11), and the hot water in the hot water storage tank 2 reaches the boiling temperature T ° C (eg, 90 ° C). Is detected by the temperature sensor 6 (S12), the power supply to the heating element 5 is stopped (S9), and the power supply control is terminated (S10). The boiling control in this night time zone is performed in the first embodiment.
Is the same as

If it is during the daytime (S3), the temperature sensor 6 detects the temperature of the mounting portion of the temperature sensor 6 of the hot water storage tank 2, that is, the presence or absence of the remaining hot water (S4). When a low temperature equal to or lower than the predetermined value is detected, the controller 7 determines that the remaining hot water amount has become equal to or lower than the predetermined amount (S5), and detects the temperature of the water supplied to the hot water storage tank 2 with the temperature sensor 6 (S1).
3), energization of the heating element 5 is started (S6).

If the feed water temperature detected by the temperature sensor 6 is equal to or lower than a predetermined temperature (for example, 15 ° C.) (S14), it is determined whether or not a predetermined time (for example, 10 hours) has elapsed since the start of the daytime, that is, in the evening. It is determined whether 5:00 has passed (S7), and if it is determined that 10 hours have passed,
Power supply is stopped regardless of the boiling temperature (S9), and power supply control is stopped (S10). If 10 hours have not elapsed, energization is continued, and when the temperature sensor 6 detects that the boiling temperature has reached T1 ° C. (for example, 70 ° C.) (S
8) The energization of the heating element 5 is stopped (S9), and the energization control is ended (S10). Here, the boiling temperature T1 is set lower than the boiling temperature T in the night time zone. If 10 hours have passed since the start of the daytime during the boiling (S7), the power supply is stopped at that time (S7).
9) The energization control ends (S10).

When the supply water temperature is equal to or higher than the predetermined temperature (15 ° C.) (S14), the amount of hot water in the hot water storage tank 2 is reduced, so that it is not necessary to boil a large amount during the daytime. Therefore, control is performed as follows. It is determined whether or not a predetermined time (for example, 5 hours) has elapsed since the start of the daytime zone, that is, whether or not 12:00 has passed (S15).
If the time has elapsed, the power supply is stopped regardless of the boiling temperature (S9), and the power supply control is stopped (S10). Here, the predetermined time (5 hours) is shorter than the case where the temperature of the supply water is low, and is set so that the time for stopping the power supply is longer.

If five hours have not passed, (S
15), energization is continued, and the temperature sensor 6 raises the boiling temperature T2.
When it is detected that the temperature reaches 50 ° C. (50 ° C.) (S16), the power supply to the heating element 5 is stopped (S9), and the power supply control is terminated (S10). The boiling temperature T2 is set lower than the boiling temperature T in the nighttime zone, and further lower than the boiling temperature T1 when the temperature of the water supply water is low. If 5 hours have passed since the start of the daytime during the boiling (S
15) At that time, the energization is stopped (S9), and the energization control is ended (S10).

As described above, in the second embodiment, the boiling temperature in the daytime zone is controlled to be lower than the boiling temperature in the nighttime zone, and even in the daytime zone, after 5 o'clock in the evening. For example, the heating element 5 is not energized, and when the temperature of the water supply water is high, the time limit for energizing the heating element in the daytime period is made longer to lower the boiling temperature. Therefore, in summer when the temperature of the water supply water is high, the power supply to the heating element during the daytime is reduced, and the electricity bill can be further reduced while preventing the hot water from running out.

Embodiment 3 FIG. Next, a third embodiment of the present invention will be described with reference to FIGS. 3, 8, and 9. FIG. FIG.
FIG. 9 is a flowchart of the control of boiling the electric water heater in the third embodiment. 8 and 9 are described as a system configuration diagram and a block diagram of a conventional electric water heater, however, the configuration of the electric water heater in the third embodiment is also substantially the same, The difference is that a setting means is provided. Hereinafter, the boiling control will be described with reference to the flowchart of FIG.

The energization control is started (S1), and the user operates the operation unit 8 to set an energizable time (for example, 7 hours) (S17). The control unit 7 detects the energization time zone (S
2) If it is not during the daytime, that is, if it is during the nighttime (S3), the power supply to the heating element 5 is started (S11).
The hot water in the hot water storage tank 2 is heated to a temperature T ° C (for example, 90 ° C).
° C) is reached by the temperature sensor 6 (S1
2) The energization of the heating element 5 is stopped (S9), and the energization control ends (S10).

If it is during the daytime (S3), the temperature sensor 6 detects the temperature of the mounting portion of the temperature sensor 6 of the hot water storage tank 2, that is, the presence or absence of remaining hot water (S4). When a low temperature equal to or lower than the predetermined value is detected, the controller 7 determines that the remaining hot water amount has become equal to or lower than the predetermined amount (S5), and starts energization of the heating element 5 (S6).

Next, it is determined whether the set energizable time (7 hours) has elapsed since the start of the daytime zone, that is, whether it has passed 2:00 pm (S18). When it is determined that seven hours have elapsed from the start of the daytime, the power supply is stopped regardless of the boiling temperature (S9), and the power supply control is terminated (S10). If seven hours have not elapsed, the boiling is continued and the temperature sensor 6 detects T1 ° C. (70 ° C.).
° C) (S8), the energization of the heating element 5 is stopped (S9), and the energization control is terminated (S8).
10). If seven hours have elapsed since the start of the daytime during boiling (S18), the power supply is stopped regardless of the boiling temperature (S9), and the power supply control ends (S10).

In the above description, the power supply restriction time is set by setting the time during which power can be supplied from the start of the daytime time zone. However, the power supply restriction time may be directly set. Alternatively, a time at which energization is stopped may be set. Each time the energization control is started, S
Although the user sets the power supply restriction time at 17, the power supply restriction time set by the user in the past may be stored, and the power supply restriction time may be read. Furthermore, the energization limit time may be changed during energization control (for example, during a night time zone).

As described above, according to the electric water heater in the third embodiment, the user himself / herself can limit the energizing time to the heating element during the daytime on the basis of the usual hot water usage. The power supply to the heating element can be reduced according to the user's lifestyle, and the electricity bill can be saved while further preventing running out of hot water.

Embodiment 4 FIG. In each of the above-described embodiments, the power supply to the heating element 5 is stopped after a predetermined time has elapsed after the daytime time zone has started, and no boiling is performed. Only in such a case, boiling may be performed. For example, a plurality of temperature sensors are provided on the side surface of the hot water storage tank 2 so that the amount of remaining hot water can be detected more finely. Even during the daytime period, the power supply is restricted (for example, from 5:00 pm to 11:00 pm). When the amount of remaining hot water is extremely small, the heating element 5 is energized to perform boiling. If the boiling control is performed in this manner, the electricity bill can be saved and running out of hot water can be reliably prevented.

Embodiment 5 FIG. Next, a fifth embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a flowchart of the control of boiling the electric water heater in the fifth embodiment. 5 and 6 are a system configuration diagram and a block diagram of an electric water heater according to a fifth embodiment. The basic configuration is a system configuration diagram and a block diagram of a conventional electric water heater shown in FIGS. It is almost the same, except that another temperature sensor 6a for detecting the amount of remaining hot water in the hot water storage tank 2 is added. Temperature sensor 6
“a” is attached to the upper part of the hot water storage tank 2 from the temperature sensor 6, and the temperature sensor 6 a can detect that the amount of remaining hot water in the hot water storage tank 2 is smaller than that of the temperature sensor 6.
Therefore, since the parts configuration is the same, the description will be omitted, and only the boiling control will be described.

When the energization control is started (S1), the control unit 7
Detects the energization time zone (S2). If it is not the daytime zone, that is, if it is the nighttime zone (S3), the power supply to the heating element 5 is started (S11), and the temperature of the hot water in the hot water storage tank 2 reaches the boiling temperature T ° C (for example, 90 ° C). When the temperature sensor 6 detects this (S12), the power supply to the heating element 5 is stopped (S9), and the power supply control ends. (S10)

If it is during the daytime (S3), the temperature sensor 6 detects the temperature of the mounting portion of the temperature sensor 6 of the hot water storage tank 2, that is, the presence or absence of the remaining hot water (S4). When detecting a low temperature below a predetermined value, the control unit 7
And the remaining hot water amount in the hot water storage tank 2 becomes a predetermined value Q1 (for example, 300
L) It is determined that the temperature has become below (S5), the temperature of the water supplied to the hot water storage tank 2 is detected by the temperature sensor 6 (S13), and the power supply to the heating element 5 is started. (S6)

The temperature sensor 6a determines that the amount of remaining hot water is Q2 (for example, 2
00L) or less (S19), the amount of hot water in the hot water storage tank 2 is large, and it is necessary to boil a large amount during the daytime. Therefore, it is determined whether or not a predetermined time (for example, 10 hours) has elapsed since the start of the daytime period, that is, whether or not 5:00 has passed in the evening (S7). The energization is stopped irrespective of the temperature rise (S9), and the energization control is stopped (S1).
0). If 10 hours have not elapsed, the power supply to the heating element 5 is continued, and the temperature sensor 6 detects the boiling temperature T3.
(For example, 80 ° C.) (S2
1) The energization of the heating element 5 is stopped (S9), and the energization control is terminated (S10). If 10 hours have passed since the start of the daytime during the boiling (S7), the power supply to the heating element 5 is stopped at that time (S9), and the power supply control is terminated (S10).

On the other hand, if the temperature sensor 6a detects that the remaining hot water amount is equal to or more than Q2 (for example, 200 L) (S19), the supply water temperature detected by the temperature sensor 6 is increased to a predetermined temperature (for example, 15
° C) or less (S14), it is determined whether a predetermined time (for example, 7 hours) has elapsed since the start of the daytime zone and whether 2 o'clock in the daytime has passed (S20), and 7 hours have elapsed. If it is determined, regardless of the boiling temperature,
Power supply to the heating element 5 is stopped (S9), and power supply control is stopped (S10). Also, if 7 hours have not passed,
When the power supply to the heating element 5 is continued and the temperature sensor 6 detects that the temperature has reached the boiling temperature T1 (for example, 70 ° C.) (S
8) The energization of the heating element 5 is stopped (S9), and the energization control is ended (S10). If seven hours have elapsed since the start of the daytime during the boiling (S20), the power supply to the heating element 5 is stopped at that time (S9), and the power supply control is terminated (S10).

The remaining hot water amount is Q2 (for example, 2
00L) or more (S19), and when the feedwater temperature detected by the temperature sensor 6 is equal to or higher than a predetermined temperature (for example, 15 ° C.) (S14), the amount of hot water in the hot water storage tank 2 is small. There is no need to boil a lot during the time.
Therefore, control is performed as follows. It is determined whether or not a predetermined time, for example, 5 hours, has passed since the daytime began, that is, whether or not 12:00 has passed (S15). If it is determined that 5 hours have passed, regardless of the boiling temperature, Then, the power supply to the heating element 5 is stopped (S9), and the power supply control is stopped (S10). Here, the predetermined time (5 hours) is shorter than the case where the temperature of the supply water is low, and is set so that the time for stopping the power supply is longer.

If 5 hours have not elapsed, the power supply to the heating element 5 is continued, and the temperature sensor 6 detects the boiling temperature T.
2 (for example, 50 ° C.) (S1
6) The energization of the heating element 5 is stopped (S9), and the energization control is ended (S10). If five hours have passed since the start of the daytime during the heating (S15), the power supply is stopped at that time (S9), and the power supply control is terminated (S1).
0).

As described above, in the fifth embodiment, even in the daytime, after 5:00 in the evening, power is not supplied to the heating element 5 and the amount of remaining hot water is large.
When the temperature of the water supply water is high, the restriction on energization of the heating element 5 in the daytime period is made longer, and the respective boiling temperatures T3, T1, T2 in the daytime period are set to, for example, 80 ° C., 70 ° C., 50 ° C.
° C, which is lower than the boiling temperature of 90 ° C during the night time. Therefore, in summer, when the amount of remaining hot water is large and the temperature of the supply water is high, the power supply to the heating element 5 during the daytime is further reduced, and the electricity bill can be further reduced while preventing running out of hot water.

Embodiment 6 FIG. Next, a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a flowchart of the control of boiling the electric water heater according to the sixth embodiment. 4 and 5 have been described as a system configuration diagram and a block diagram of the electric water heater according to the fifth embodiment. However, since the configuration of the electric water heater according to the sixth embodiment is the same, description thereof will be omitted. Also, the boiling control is almost the same as in the sixth embodiment, and therefore only the changed contents will be described.

In the fifth embodiment, after the energization is started (S
6) The current supply limit time to the heating element 5 is changed based on the remaining hot water amount at the present time. The amount of hot water is stored in the storage means in the control unit 7 (S25), and when the heating element 5 is energized and boiled during the daytime, the previous day stored in the storage means in the control unit 7 is stored. Remaining hot water quantity Q
2 or based on the average value of the remaining hot water amount in the past few days (S
24), the power supply restriction time to the heating element 5 is changed.

As described above, in the sixth embodiment, power is not supplied to the heating element 5 after 5:00 in the evening, even during the daytime, and the amount of remaining hot water Q
Based on 2, if the remaining hot water is large and the feedwater temperature is high,
The power supply to the heating element 5 in the daytime period is made longer, and the respective boiling temperatures T3, T1, T in the daytime period are increased.
2 is lower than the boiling temperature T in the night time zone.
Therefore, in summer, when the amount of remaining hot water is large and the temperature of the supply water is high, the power supply to the heating element 5 during the daytime is reduced, and the electricity bill can be further reduced while reliably preventing running out of hot water.

[0044]

According to the electric water heater according to the present invention, energization of the heating means is restricted for a predetermined period of time during the daytime until the start of the nighttime zone, and the boiling temperature in the daytime zone is controlled during the nighttime. Since the temperature is lower than the boiling temperature in the time zone, the electricity supply to the heating means in the daytime zone is reduced, and the electricity bill can be saved while running out of hot water.

Further, the power supply to the heating means is restricted for a predetermined time until the start of the night time zone during the daytime, and the predetermined time is changed in accordance with the water supply water temperature. In summer, the power supply to the heating means during the daytime is reduced, and the electricity bill can be further saved while preventing running out of hot water.

Since the boiling temperature during the daytime is changed according to the temperature of the water supply, in summer when the temperature of the water supply is high, the power supply to the heating means during the daytime becomes less and the running out of hot water is reduced. Prevention while saving more on electricity bills.

Further, since the time for restricting the power supply to the heating means can be set by the user's own operation, the power supply to the heating means in the daytime can be reduced in accordance with the user's lifestyle, and the water can be further drained. Prevent and save on electricity bills.

In addition, the energizing time to the heating means during the daytime period is limited, and the time limit is changed according to the remaining hot water amount and the temperature of the supply water. Electricity to the heating means during the time period is further reduced, and electricity bills can be saved while running out of hot water.

Furthermore, the energizing time to the heating means in the daytime period is limited, and the time limit is changed according to the past amount of remaining hot water and the temperature of the supply water. Therefore, in summer when the amount of remaining hot water is large and the temperature of the supply water is high, In addition, the electricity supply to the heating means during the daytime is reduced, and the electricity bill can be further saved while reliably preventing running out of hot water.

[Brief description of the drawings]

FIG. 1 is a flowchart of boiling control of an electric water heater according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart of a control of boiling an electric water heater according to Embodiment 2 of the present invention.

FIG. 3 is a flowchart of a control of boiling water of an electric water heater according to Embodiment 3 of the present invention.

FIG. 4 is a system configuration diagram of an electric water heater according to Embodiments 5 to 6 of the present invention.

FIG. 5 is a block diagram of an electric water heater according to Embodiments 5 to 6 of the present invention.

FIG. 6 is a flowchart of a control for boiling water of an electric water heater according to Embodiment 5 of the present invention.

FIG. 7 is a flowchart of the control of boiling of an electric water heater according to Embodiment 6 of the present invention.

FIG. 8 is a system configuration diagram of Embodiments 1 to 4 of the present invention and a conventional electric water heater.

FIG. 9 is a block diagram of Embodiments 1 to 4 of the present invention and a conventional electric water heater.

FIG. 10 is a flowchart of a conventional electric water heater boiling control.

[Explanation of symbols]

1 Electric water heater body, 2 Hot water storage tank, 5 Heating element, 6
Temperature sensor, 6a temperature sensor, 7 control unit, 8 operation unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Kazama 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsui Electric Co., Ltd. (72) Hideto Shinohara 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (6)

[Claims] 1. A hot water storage tank, a heating means for heating water in the hot water storage tank, a temperature sensor for detecting a boiling temperature, an amount of remaining hot water, and a temperature of supply water, and an energization for distinguishing between daytime hours and nighttime hours A time zone detecting means, for a predetermined time until the start of the night time zone during the daytime, restricting the energization to the heating means, and setting the boiling temperature in the daytime zone to be lower than the boiling temperature in the nighttime zone. An electric water heater characterized by being lowered. 2. A hot water storage tank, a heating means for heating water in the hot water storage tank, a temperature sensor for detecting a boiling temperature, an amount of remaining hot water, and a supply water temperature, and a power supply for distinguishing between daytime and nighttime hours. A time zone detecting unit, wherein the power supply to the heating unit is restricted for a predetermined time until the start of the night time zone during the daytime, and the predetermined time is changed according to the temperature of the water supply. Water heater. 3. The electric water heater according to claim 1, wherein the boiling temperature in the daytime is changed according to the temperature of the feed water. 4. The electric water heater according to claim 1, further comprising an operation section for setting a time period for restricting energization of the heating means. 5. The electric water heater according to claim 1, further comprising a plurality of temperature sensors for detecting a remaining hot water amount, and changing a time for restricting energization to the heating means in accordance with the remaining hot water amount and the temperature of the supply water. . 6. A plurality of temperature sensors for detecting a remaining hot water amount,
2. The electric water heater according to claim 1, further comprising storage means for storing the amount of the remaining hot water in the past, and changing the time for limiting the energization to the heating means in accordance with the amount of the remaining hot water in the past and the temperature of the supply water.