JP2000130851A - Electric water heater and method for controlling its heating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set low a water-heat-up temperature and insulating temperature of hot water in summer season by altering a heating operation of a heater of an electric water heater in the summer season and in the winter season. SOLUTION: A water guide member 10 such as a pipe for guiding input water to a temperature sensor S is provided in a dispersing implement mounted in a water supply port 3 of the electric water heater D. At the time of outputting hot water, water fed from the port 3 into the tank 1 is guided to the vicinity of the sensor S through the member 10, and directly sprayed from a spouting outlet 11 to toward the sensor S. Thus, the sensor S can effectively sense a supply water temperature. When hot water started outputting, a sensed water temperature of the sensor S is gradually lowered, and then arrives at substantially equal water temperature to supply water temperature. In summer season, since the supply water temperature is higher than that in winter season, the arrival water temperature is also high in the summer season. In the summer season in which the arrival water temperature is lower than the threshold value, a water-heat-up temperature and heat insulating temperature are set to a lower value to save its electric energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-water storage type electric water heater, and more particularly, to an electric water heater which is installed in a room such as a kitchen or a vanity stand, and which has a simple structure and can be adapted to seasonal and other environmental changes. Accordingly, it is an object of the present invention to be able to automatically change the setting of the boiling water temperature or the heat retaining temperature of hot water.

[0002]

2. Description of the Related Art Generally, electric water heaters installed in kitchens, vanities, and the like are set so that hot water stored in a hot water storage tank is always kept at a constant temperature and hot water at a constant temperature can be supplied as much as possible. . However, since high-temperature hot water is not required much in summer, keeping the stored hot water at a high temperature is a wasteful consumption of electric energy.

[0003] Japanese Patent Application No. 7-131711 (Japanese Patent Application Laid-Open No.
No. 5248), the season is determined by a temperature sensor that detects the outside air temperature, the amount of hot water stored is reduced in summer in comparison with winter, and the start time of boiling is further reduced by combining a solar radiation sensor that determines day and night. An electric water heater is described which controls to shorten the heat radiation time and to perform the heating of the water in a time period when the electricity rate is low. By adopting such prior application technology, it is said that the amount of electricity used can be adjusted according to the seasonal change, and the electricity bill can be saved.

[0004]

The electric water heater described in the prior application requires a temperature sensor for detecting the outside air temperature and a solar radiation sensor for day / night discrimination in order to control the heating of water. Must be installed outdoors or in an environment close to the outdoors. Therefore, there is a problem that it is difficult to apply the present invention to an electric water heater installed in a room of a house or a building such as a kitchen or a vanity stand.

[0005]

SUMMARY OF THE INVENTION The present invention provides means for controlling the heating of an electric water heater installed in a room in accordance with seasonal changes. A feature of the heating control method of the electric water heater adopted by the present invention for achieving the above object is to detect the temperature of water supplied into the hot water storage tank and control the heating operation of the heater. That is, since the temperature of the water flowing into the hot water storage tank decreases in winter, by detecting this, the boiling temperature and the heat retention temperature of the hot water are set to higher values. On the other hand, when it is detected that the temperature of the water flowing into the hot water storage tank is high, such as in summer, the boiling water temperature and the heat retention temperature are set low.

The present invention provides another heating control method, which is characterized by controlling a heating operation of a heater based on a temperature drop rate of hot water stored in a hot water storage tank. It is in. In a warm state where hot water is not used, the rate of temperature drop of hot water in summer is slower than in winter. By detecting the temperature drop rate, it is possible to automatically change the setting of the boiling water temperature and the heat retention temperature between summer and winter, for example.

As means for detecting the temperature drop rate of hot water,
A method of controlling the heating operation of the heater based on the detection of the length of time from the stop of energization to the start of energization to the start of energization of the heater in the hot water keeping state can be adopted. In general, the electric water heater is configured such that when the temperature of the hot water drops by a certain temperature (for example, about 10 ° C.) from a preset heat retaining temperature,
The configuration is such that energization of the heater is started to heat the hot water, and energization of the heater is stopped when the temperature of the hot water reaches the heat retention temperature. Therefore, by detecting the length of time from when the power supply to the heater is stopped to when the power supply is started, it is possible to know environmental changes such as seasons, and it is possible to automatically change the setting between summer and winter. it can.

Further, the present invention is characterized in that the electric water heater adopted for carrying out the heating control method according to claim 1 is characterized in that water supplied from a water supply port into a hot water storage tank is
There is provided a water guiding means for guiding from the water supply port to a temperature sensor provided in the hot water storage tank. With such a configuration, since the water flowing into the hot water storage tank is directly blown to the temperature sensor, the detection of the supply water temperature is ensured,
It is possible to accurately determine environmental changes such as seasons.
Further, the installation of the water guide means has an advantage that the limitation on the mounting position of the temperature sensor is reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an electric water heater D according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the electric water heater D has a hot water storage tank 1 built therein, and a hot water outlet 2 is provided at a center of a ceiling of the hot water storage tank 1, and a water supply port 3 is provided at a center of a bottom of the hot water storage tank. The tap 2 is connected to a tap 6 of the water heater D by a hot water supply pipe 4, and the tap 3 is connected to a water supply 7 of the hot water D by a feed pipe 5 via a pressure reducing valve 8.
In the hot water storage tank 1, a heater H for boiling stored water to a predetermined temperature and keeping the temperature warm is provided. A temperature sensor S is provided at an appropriate position in the tank 1, for example, near the heater H as shown in the figure. The heater H and the temperature sensor S are disposed and connected to the control unit 20 disposed at an appropriate position in the electric water heater D, and based on the temperature information detected by the temperature sensor S or the operation status of the heater H itself, It is configured to control the heating operation of the heater H.

A feature of the electric water heater D of the present embodiment is that a dispersing device 9 for diffusing water flowing into the tank 1 is attached to the water supply port 3, and a plurality of dispersing devices 9 formed on the dispersing device 9 are formed. Is provided with a water guide member 10 for guiding water flowing from the water supply port 3 to a temperature sensor S provided in the tank 1 in one of the water passage holes 9a. The water guide member 10 is formed of, for example, a pipe.

The electric water heater D configured as described above, when water is introduced from the water supply port 3 into the tank 1 for tapping water,
The hot water in the tank 1 is pushed up by the water flowing from the water supply port 3 and is sent out from the hot water outlet 2 to the outside. At this time, as shown in FIG. 2, a part of the inflowing water is guided to the vicinity of the temperature sensor S through the water guide member 10 and is blown directly from the outlet 11 toward the temperature sensor S. Therefore, the temperature sensor S is connected to the hot water storage tank 1
And it is possible to reliably detect the temperature of the supplied water.

When the inside of the tank 1 is kept warm, the temperature sensor S detects the warming temperature. When the hot water is started, the inflowing water is directly blown to the temperature sensor S through the water guiding member 10. As shown in FIG. 3, the detected water temperature gradually decreases, and eventually reaches a temperature substantially equal to the supply water temperature. The water supply temperature varies depending on the season, and the water supply temperature in summer (for example, 25 ° C.) is higher than the water supply temperature in winter (for example, 5 ° C.). Is higher than in winter. Therefore, a fixed threshold value is set for the detected water temperature at the time of tapping, and when the reached water temperature falls below the threshold value, it is determined that the climate is winter or equivalent, and the boiling water temperature and the warming temperature of the hot water are increased. Set. Conversely, when the reached water temperature does not drop below the threshold value, it is determined that the weather is summer or similar, and the boiling water temperature and the heat retention temperature of the hot water are set low to save electric energy.
At this time, the temperature gradient at the time of the water temperature drop becomes gentle in summer when the water supply temperature is high, and becomes steep in winter. Therefore, by providing a means for detecting the magnitude of the temperature gradient,
The level of the supply water temperature can be determined more accurately.

The temperature around the temperature sensor S is locally reduced because water is sprayed through the water guide member 10. Therefore, by arranging the temperature sensor S near the heater H as shown in the drawing, the temperature of the hot water around the temperature sensor S can be quickly recovered, and the stability of the temperature detection can be improved. Further, in this manner, the single temperature sensor S can be used for both the detection of the hot water storage temperature and the detection of the supply water temperature.

Incidentally, the electric water heater D according to the present invention comprises:
The following control can be used together. Since the outside air temperature differs between summer and winter, the temperature of the hot water kept in the hot water storage tank 1 decreases at a different rate, and the temperature decreases more slowly in summer than in winter. By utilizing this, it is possible to determine environmental changes such as seasons. Specifically, the magnitude of the temperature drop rate is determined as follows.

Generally, as shown in FIG. 4, when the temperature of the hot water stored in the tank 1 is equal to or higher than a preset temperature, the power supply to the heater is stopped, and the temperature of the hot water is reduced by heat radiation. When the temperature drops by a certain temperature (usually a temperature appropriately set in the range of 5 to 15 ° C.), the heater is energized to heat the hot water until it reaches the heat retention temperature. In summer, the temperature of the hot water drops slowly because the temperature is higher than in winter. Therefore, the time t from when the power supply to the heater is stopped to when the power supply to the heater is restarted is t.
₂ is longer than the time t ₁ in winter. Therefore, the length of time the heater is turned off / on while the hot water is not being used is detected, and if this time length exceeds a certain value, it is determined that the climate is summer or equivalent, and the hot water is heated. Set the heating temperature and heat retention temperature lower than in winter.

Note that the above-described heater control method based on the water supply temperature is not executed unless hot water is used.
Therefore, it is desirable to use the above-described heater control method based on the OFF / ON time length of the heater in case the hot water is not used for a long time. However, when both control methods are used together, the former control method based on the water supply temperature is prioritized over the latter control method based on the heater OFF / ON time length.

According to the present invention, the heating operation of the heater is made different between summer and winter, for example, so that the boiling water temperature and the heat retention temperature are set low in summer and high in winter. Specific temperature set values can be changed as appropriate. Further, the user may be allowed to arbitrarily select a temperature set value.

The switching of the heating operation of the heater is as follows.
In addition to the two types of summer and winter, it is conceivable to prepare settings corresponding to spring and autumn. Other than that, the embodiments of the present invention do not prevent appropriate changes according to the situation.

[0019]

According to the present invention, by detecting the temperature of the water supplied into the hot water storage tank, or by detecting the rate of temperature decrease of the hot water at the time of keeping the temperature, it is possible to determine the environmental change such as the season. can do. Therefore, at a time when hot water is not needed much, such as in summer, it is possible to save the electric energy by lowering the set values of the boiling water temperature and the heat retaining temperature. In addition, the present invention can be easily applied to an electric water heater installed in a room such as a kitchen or a vanity room.

Further, the electric water heater according to the present invention is provided with a water guide member for guiding water supplied from the water supply port into the tank to the temperature sensor. Restrictions on the mounting position of the sensor can be reduced. Therefore, the temperature sensor can be mounted at an optimum position for detecting the temperature of the hot water, so that it is possible to execute fine temperature control with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an electric water heater according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view according to one embodiment of the present invention, showing a schematic configuration of a lower portion of a hot water storage tank incorporated in an electric water heater.

FIG. 3 is a graph showing a change in water temperature detected by a temperature sensor at the time of tapping, according to an embodiment of the present invention, in which a broken line indicates a change in water temperature in summer and a solid line indicates a change in water temperature in winter. is there.

FIG. 4 is a graph showing a change in water temperature in a warm state, according to one embodiment of the present invention, in which a broken line indicates a change in water temperature in winter and a solid line indicates a change in water temperature in summer.

[Explanation of symbols]

D: Electric water heater H: Heater S: Temperature sensor 1
… Hot water storage tank 2… tap hole 3… water supply port 4… tapping pipe
5 ... water supply pipe 6 ... hot water supply section 7 ... water supply section 8 ... pressure reducing valve 9
... dispersing tool 9a ... water hole 10 ... water guide member 11 ... outlet 20 ... control board

Claims (4)

[Claims] 1. A heating control method for an electric water heater, comprising detecting a temperature of water supplied into a hot water storage tank and controlling a heating operation of a heater. 2. A heating control method for an electric water heater, comprising controlling a heating operation of a heater based on a temperature drop rate of hot water stored in a hot water storage tank. 3. The heating control method for an electric water heater according to claim 2, wherein the heating operation of the heater is controlled based on a length of time from when power supply to the heater is stopped to when power supply to the heater is started in a state where the hot water is kept warm. . 4. An electric water heater, comprising: water guide means for guiding water supplied from the water supply port into the hot water storage tank to a temperature sensor provided in the hot water storage tank from the water supply port.