JP5017924B2 - Electric water heater - Google Patents

Description

  The present invention relates to an electric water heater.

  Conventionally, in this type of electric water heater, as shown in FIG. 5, the low temperature water stored in the upper portion of the hot water storage tank 51 is heated by the heater 52, and the hot water temperature reaches the first predetermined temperature. When the temperature detection part 53 provided in the upper part of the heater detects the temperature, the heater 52 is turned off and the pump 55 provided in the middle of the circulation pipe 54 communicating with the lower part and the upper part of the hot water storage tank 51 is driven. The pump 55 continues to be driven until the temperature detection unit 53 detects a second predetermined temperature that is lower than the first predetermined temperature. When the driving of the pump 55 is stopped, the heater 52 is turned on again to heat the low-temperature water stored in the lower part of the hot water storage tank 51.

While the above boiling operation is repeated, the hot water in the hot water storage tank 51 rises in temperature as a whole, but a certain time elapses after the temperature detection unit 53 detects the first predetermined temperature and drives the pump 55. However, if the second predetermined temperature is not detected, the heater 52 and the pump 55 are stopped and the boiling operation is completed (see, for example, Patent Document 1).
JP-A-7-286755

  However, in the conventional configuration, the temperature detection unit (thermistor) provided in the upper part of the hot water storage tank used for controlling the heating operation may fail, and the normal heating operation may not be performed. . The failure of the thermistor here refers to a state in which the hot water temperature cannot be detected due to disconnection or short circuit between the thermistor and the control board. And when a thermistor broke down, the hot water in the lower part of a hot water storage tank flowed into the pump, and the subject that the durability of a pump was reduced occurred.

  In order to solve the above-described conventional problems, an electric water heater of the present invention includes a heater provided in an upper part of a hot water storage tank, a circulation path connected from the lower part of the hot water storage tank to the upper part of the hot water storage tank via a circulation pump, and the hot water storage A thermistor positioned from the upper part to the lower part of the tank, and if the temperature detected by the thermistor located at the uppermost part of the hot water storage tank is equal to or higher than a third predetermined temperature, the circulating pump is driven and is lower than the third predetermined temperature. The circulating pump is stopped and the boiling operation is performed, and the boiling operation is terminated when the thermistor located at the lowermost part of the hot water storage tank detects a second predetermined temperature or higher which is lower than the third predetermined temperature. The electric water heater has a control base for detecting a failure of the thermistor, and the control base is at the bottom of the hot water storage tank. When detected, if the temperature detected by the thermistor located at the top of the hot water storage tank is equal to or higher than a fourth predetermined temperature lower than the third predetermined temperature, the circulating pump is driven, and if lower than the fourth predetermined temperature, The circulating pump is stopped and the boiling operation is performed.

  Thereby, at the time of a failure in which the temperature is not detected due to disconnection or short circuit between the lowermost thermistor and the control base, it is possible to suppress the high temperature of the water entering the circulation pump and raise the durability of the circulation pump in the boiling operation.

  The electric water heater of the present invention drives the circulation pump if the temperature detected by the thermistor located at the top of the hot water storage tank is equal to or higher than the third predetermined temperature, and stops the boiling if the temperature is lower than the third predetermined temperature. A fourth predetermined temperature at which the temperature detected by the thermistor located at the top of the hot water tank is lower than the third predetermined temperature when the control board detects a failure of the thermistor located at the bottom of the hot water tank. If it is above, the circulation pump is driven, and if it is lower than the fourth predetermined temperature, the circulation pump is stopped and the boiling operation is performed.

  As a result, the thermistor at the bottom of the hot water storage tank suppresses the high temperature of incoming water to the circulation pump in the event of a failure where the temperature is not detected due to disconnection or short circuit between the bottom thermistor and the control board. Can raise the sex.

  According to a first aspect of the present invention, there is provided a heater provided at an upper portion of the hot water storage tank, a circulation path connected from the lower portion of the hot water storage tank to the upper portion of the hot water storage tank via a circulation pump, and a thermistor positioned from the upper portion to the lower portion of the hot water storage tank. And if the temperature detected by the thermistor located at the top of the hot water storage tank is equal to or higher than a third predetermined temperature, the circulating pump is driven, and if the temperature is lower than the third predetermined temperature, the circulating pump is stopped and the boiling operation is performed. And detecting the failure of the thermistor in the electric water heater that terminates the heating operation when the thermistor located at the lowermost part of the hot water storage tank detects a temperature equal to or higher than a second predetermined temperature lower than the third predetermined temperature. A control base, and when the control base detects a failure of a thermistor located at the bottom of the hot water storage tank, The circulating pump is driven if the temperature detected by the installed thermistor is equal to or higher than a fourth predetermined temperature lower than the third predetermined temperature, and when the temperature is lower than the fourth predetermined temperature, the circulating pump is stopped and the boiling operation is performed. It is an electric water heater designed to be used.

  As a result, when the thermistor at the bottom of the hot water storage tank fails due to a disconnection or short circuit between the thermistor at the bottom of the hot water tank and the control base, the thermistor at the top of the hot water storage tank sets the predetermined boiling temperature to the set temperature. By switching to a lower temperature, it is possible to increase the durability of the circulation pump by suppressing the high temperature of incoming water to the circulation pump.

A second invention is, in particular, in the first invention, when the control board detects the failure of the thermistor located at the lowest portion of the hot water storage tank, the temperature detected by the thermistor at the bottom nearest the hot water storage tank, the second If the temperature is equal to or higher than the predetermined temperature, the circulating pump is driven. If the temperature is lower than the second predetermined temperature, the circulating pump is stopped and the boiling operation is performed.

  According to this, when the thermistor at the bottom of the hot water tank fails, it is controlled using the thermistor closest to the bottom of the hot water tank, so that the hot water temperature to the circulating pump is suppressed and the durability of the circulating pump is increased. Can do.

The third invention is the first invention, the fourth predetermined temperature is intended to be variable the value depending on the season, by suppressing the high temperature water inlet temperature to the circulating pump, the durability of the circulating pump Can raise the sex.

Furthermore, by generating the minimum required amount of hot water in the hot water storage tank according to the season, unnecessary electricity bills are not required .

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

  (Embodiment 1) FIG. 1: shows the figure of the electric water heater in Embodiment 1 of this invention.

In FIG. 1, an electric water heater 1 stores hot water supplied from a water supply pipe 9 in a hot water storage tank 2, and is heated by a heater 4 attached to the upper part of the hot water storage tank 2 to perform a boiling operation. It is. Further, the hot water storage tank 2 is provided with thermistors (TH1 to TH5) arranged substantially evenly on the side surfaces thereof, and the control board 7 performs ON / OFF control of the circulation pump 3 and the heater 4 according to the temperature detected by the thermistor. The boiling operation is performed. The hot water storage tank 2 is filled with high temperature hot water by the boiling operation, and the user can use the hot water from the hot water discharge pipe 10 connected to the upper part of the hot water storage tank 2.

  Here, a detailed control procedure for the boiling operation will be described with reference to FIG. First, when the temperature detected by the uppermost thermistor TH1 installed in the hot water storage tank 2 reaches a first predetermined temperature (for example, 25 degrees), the heater 4 is energized (S01).

  Next, the control board 7 determines whether the lowermost thermistor TH5 has a failure in which the temperature is not detected due to disconnection or short circuit between the lowermost thermistor TH5 and the control board 7 (S02). It is determined whether the temperature detected by the lower thermistor TH5 is higher at the control board 7 than the second predetermined temperature (for example, 78 ° C.) higher than the first predetermined temperature (for example, 25 degrees) (S03).

  If the temperature detected by the lowermost thermistor TH5 is higher than the second predetermined temperature in S03, the circulation pump 3 is stopped (S07), the energization of the heater 4 is stopped (S08), End boiling operation.

  In S03, if the temperature detected by the lowermost thermistor TH5 has not detected a temperature higher than the second predetermined temperature, the temperature detected by the uppermost thermistor TH1 is higher than the second predetermined temperature (for example, 78 ° C.). It is determined whether or not the temperature is higher at the control board 7 than the third predetermined temperature (for example, 88 ° C.) (S04). If the uppermost thermistor TH1 detects a temperature higher than the third predetermined temperature in S04, the circulating pump 3 is operated to reduce the temperature of the uppermost thermistor TH1 (S05), and the process returns to S02. .

  If the uppermost thermistor TH1 does not detect a temperature higher than the third predetermined temperature in S04, the circulation pump 3 is stopped (S06), and the process returns to S02.

  Next, the case where it is determined in S02 that the failure is caused by the disconnection and short circuit between the lowermost thermistor TH5 and the control board 7 will be described with reference to FIG.

  Whether or not the temperature detected by the uppermost thermistor TH1 is lower in the control board 7 than the fourth predetermined temperature (for example, 80 ° C.) lower than the third predetermined temperature (for example, 88 ° C.) after being determined as a failure in S02. Is determined (S09). If the uppermost thermistor TH1 detects a temperature lower than the fourth predetermined temperature in S09, the circulation pump 3 is stopped (S10), and the process returns to S09.

  If the uppermost thermistor TH1 detects a temperature higher than the fourth predetermined temperature in S09, the circulating pump 3 is operated to reduce the temperature of the uppermost thermistor TH1 (S11), and the control board 7 is at the highest. The time during which the temperature detected by the upper thermistor TH1 is equal to or higher than the fourth predetermined temperature is measured (S12). Then, if the control board 7 detects that the temperature detected by the uppermost thermistor TH1 is equal to or higher than the fourth predetermined temperature for a predetermined time (for example, 1 minute), the circulation pump 3 is stopped (S13), and the heater 4 is stopped (S14), and the boiling operation is terminated.

  If the uppermost thermistor TH1 has not detected the fourth predetermined temperature or more for a predetermined time (for example, 1 minute), the process returns to S09 and continues until the boiling operation is completed.

As described above, in the electric water heater according to Embodiment 1 of the present invention, when the lowermost thermistor TH5 has a failure in which the temperature is not detected due to disconnection or short circuit between the lowermost thermistor TH5 and the control base 7, The heating base temperature of the uppermost thermistor TH1 is instructed by the control board 7 to switch from the third predetermined temperature (88 ° C.) to the fourth predetermined temperature (80 ° C.), and the high incoming water temperature to the circulation pump 3 is suppressed. Therefore, the durability of the circulation pump 3 can be increased, and the life of the equipment can be improved.

  3, as shown in FIG. 4, a step of determining whether the temperature detected by the thermistor TH4 closest to the lowermost part is higher than a second predetermined temperature (for example, 78 ° C.) between S11 and S12 as shown in FIG. S15) may be provided, and if the temperature detected by the thermistor TH4 closest to the bottom in S15 is lower than a second predetermined temperature (for example, 78 ° C.), S12 may be performed, and if higher, S13 may be performed.

  In this way, the lowermost thermistor TH5 controls the boiling operation using the lowermost thermistor TH4 at the time of failure in which the temperature is not detected due to disconnection or short circuit between the lowermost thermistor TH5 and the control base 7, The rise in the temperature of the incoming water of the circulation pump 3 can be suppressed, and the durability of the circulation pump 3 can be improved.

  Although the fourth predetermined temperature is set to 80 ° C. in S09 of FIG. 3, it may be set to 65 degrees during summer driving or 70 degrees during winter driving depending on the season. Accordingly, since the minimum required amount of hot water corresponding to the temperature can be stored in the hot water storage tank 2, the minimum required electricity bill can be used and the durability of the circulation pump 3 can be increased.

  Further, when a predetermined period (for example, one month) has elapsed since the control board 7 detected the failure of the lowermost thermistor TH5, a warning sound is generated using a buzzer or the like, and an abnormality is notified to the display unit of the remote controller. Informing means may be provided.

  As described above, the electric water heater according to the present invention can perform a boiling operation without impairing the durability of the circulation pump even when the thermistor fails.

Configuration of electric water heater Flowchart of boiling operation of electric water heater of Embodiment 1 Flowchart of boiling operation of electric water heater of Embodiment 1 Flowchart of boiling operation of electric water heater of embodiment 2 Configuration diagram of a conventional electric water heater

DESCRIPTION OF SYMBOLS 1 Electric water heater 2 Hot water storage tank 3 Circulation pump 4 Heater 7 Control board 9 Water supply pipe 10 Hot water outlet TH1 Uppermost thermistor TH4 Lowermost thermistor TH5 Lowermost thermistor

Claims (3)

A heater provided at the upper part of the hot water storage tank, a circulation path connected from the lower part of the hot water storage tank to the upper part of the hot water storage tank via a circulation pump, and a thermistor positioned from the upper part to the lower part of the hot water storage tank, If the temperature detected by the thermistor located at the top is equal to or higher than a third predetermined temperature, the circulating pump is driven. If the detected temperature is lower than the third predetermined temperature, the circulating pump is stopped and the boiling operation is performed. In the electric water heater that terminates the boiling operation when the thermistor located at the bottom of the thermostat detects a temperature equal to or higher than a second predetermined temperature lower than the third predetermined temperature, the control board detects a failure of the thermistor, When the control board detects the failure of the thermistor located at the bottom of the hot water tank, the thermist located at the top of the hot water tank When the temperature detected by the heater is equal to or higher than a fourth predetermined temperature lower than the third predetermined temperature, the circulating pump is driven, and when the temperature is lower than the fourth predetermined temperature, the circulating pump is stopped and the boiling operation is performed. Electric water heater. When the control board detects the failure of the thermistor located at the lowest portion of the hot water storage tank, the temperature detected by the thermistor at the bottom nearest the hot water storage tank, a circulation pump driven if the second predetermined temperature or higher, the The electric water heater according to claim 1, wherein if the temperature is lower than a second predetermined temperature, the circulating pump is stopped and a boiling operation is performed. The electric water heater according to claim 1, wherein the value of the fourth predetermined temperature is variable according to a season.

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