JP4557852B2 - How to operate an electric water heater - Google Patents

Description

  The present invention relates to an operation method of an electric water heater that stores hot water in a hot water storage tank, and particularly to an operation method of an electric water heater that can stabilize the hot water temperature by controlling the flow rate of a hot water circulation pump. It is.

  For example, as shown in FIG. 2, in an electric water heater provided with a hot water supply heat exchanger 3 that indirectly heats the tap water in the water supply pipe 1 with hot water in the hot water storage tank 2, hot water is supplied from the hot water in the upper part of the tank. Derived by the hot water supply circulation pump 31 and returned to the lower part of the tank through the primary side 3a of the hot water heat exchanger 3, while passing tap water through the secondary side 3b of the hot water heat exchanger 3 and heating it to a predetermined temperature. It is done by.

  In the current electric water heaters, the mainstream is to set the hot water supply temperature to a temperature desired by the customer. The hot water supply heat exchanger 3 is adjusted by adjusting the hot water circulation pump 31 so that the hot water supply becomes the set temperature. It is necessary to adjust the flow rate of the primary side 3a.

Here, it is possible to detect the secondary outlet temperature of the hot water heat exchanger, which is the hot water temperature, and control the flow rate of the hot water circulation pump so as to be the predetermined temperature. There is a problem that it takes time to come.
In addition, when the flow rate is suddenly changed, for example, when the flow rate is reduced from 12 L / min to 4 L / min, the hot water supply temperature is detected and the flow rate of the hot water circulation pump is controlled. Hot water comes out.
On the other hand, when the flow rate is increased from 4 L / min to 12 L / min, low-temperature hot water comes out with respect to a predetermined temperature, and the user feels uncomfortable when taking a shower.

  In view of the problems of the conventional electric water heater operating method, the present invention controls the flow rate of the hot water supply by controlling the flow rate of the hot water supply circulation pump immediately after the start of hot water supply or when there is a flow rate change of a certain flow rate or more. It aims at providing the operation method of the electric water heater which can aim at stabilization.

In order to achieve the above object, the operation method of the electric water heater of the present invention is an operation method of an electric water heater provided with a hot water heat exchanger that indirectly heats tap water in a water supply pipe with hot water in a hot water storage tank. A hot water supply flow sensor is provided on the secondary side of the heat exchanger, and temperature sensors are provided at the primary side inlet and the secondary side entrance of the hot water heat exchanger, respectively. And calculating the required amount of heat based on the value of each temperature sensor, and operating the hot water supply circulation pump at a predetermined number of revolutions based on the calculation result, the primary side of the hot water supply heat exchanger is close to the optimum circulation amount After adjusting the flow rate of the hot water circulation pump so that the outlet temperature on the secondary side of the hot water heat exchanger becomes a predetermined temperature , immediately after the hot water flow rate sensor detects a flow rate change of a certain amount or more, Hot water temperature Calculate the required amount of heat based on the set value, the hot water flow rate sensor, and the values of each temperature sensor, and operate the hot water circulation pump at a specified number of revolutions based on the calculation results to optimize the primary side of the hot water heat exchanger The flow rate of the hot water supply circulation pump is adjusted so that the outlet temperature on the secondary side of the hot water supply heat exchanger becomes a predetermined temperature after making the state close to a sufficient circulation amount .

Moreover, the inside of the hot water storage tank can be opened to the atmosphere so that no pressure is applied to the tank.

An electric heater can be used as a means for boiling hot water in the hot water storage tank.

Further, a heat pump type heating device can be used as means for boiling hot water in the hot water storage tank.

The electric water heater of the present invention is a hot water flow rate sensor on the secondary side of a hot water heat exchanger in an electric water heater provided with a hot water heat exchanger for indirectly heating tap water in a water supply pipe with hot water in a hot water storage tank. A temperature sensor is provided at each of the primary inlet and the secondary inlet / outlet of the hot water heat exchanger, and immediately after the start of hot water supply, the required amount of heat based on the hot water temperature set value, the hot water flow sensor, and the value of each temperature sensor. And the hot water circulation pump is operated at a predetermined number of revolutions based on the calculation result to bring the primary side of the hot water heat exchanger closer to the optimum circulation amount, and then the secondary side of the hot water heat exchanger Adjust the flow rate of the hot water supply circulation pump so that the outlet temperature of
When the hot water flow rate sensor detects a change in the flow rate above a certain amount, immediately after that, the required heat quantity is calculated based on the hot water temperature setting value, the hot water flow rate sensor, and the values of each temperature sensor, and the hot water circulation is based on this calculation result. By operating the pump at a predetermined number of revolutions, the primary side of the hot water heat exchanger is brought close to the optimum circulation amount, and then the outlet temperature of the secondary side of the hot water heat exchanger becomes a predetermined temperature. The flow rate of the circulation pump is adjusted.

  According to the operation method of the electric water heater of the present invention, in the operation method of the electric water heater provided with the hot water heat exchanger for indirectly heating the tap water of the water supply pipe with the hot water of the hot water storage tank, A hot water supply flow sensor is provided on the secondary side, temperature sensors are provided at the primary and secondary entrances of the hot water heat exchanger, and immediately after the start of hot water supply, the hot water supply temperature set value, the hot water flow sensor, and the value of each temperature sensor are set. Based on the calculation result, the hot water circulation pump is operated at a predetermined number of rotations to bring the primary side of the hot water heat exchanger close to the optimum circulation amount, and then hot water heat exchange Since the flow rate of the hot water supply circulation pump is adjusted so that the outlet temperature on the secondary side of the heater reaches a predetermined temperature, first, the primary side of the hot water supply heat exchanger is brought close to the optimum circulation amount, Is a given temperature and So that the flow rate of the hot water circulation pump can be finely adjusted, this makes it possible to shorten the time from the hot water supply start until the hot water of a predetermined temperature.

  In this case, when the hot water flow rate sensor detects a change in flow rate of a certain amount or more, immediately after that, the necessary heat amount is calculated based on the hot water temperature setting value, the hot water flow rate sensor, and the values of each temperature sensor, and based on this calculation result. By operating the hot water supply circulation pump at a predetermined rotational speed, the outlet side temperature on the secondary side of the hot water heat exchanger becomes a predetermined temperature after making the primary side of the hot water heat exchanger close to the optimum circulation amount. By adjusting the flow rate of the hot water supply circulation pump in this way, the hot water supply temperature is set to a predetermined temperature after the primary side of the hot water supply heat exchanger after the change is in a state close to the optimum circulation amount even when the flow rate changes suddenly. Since the flow rate of the hot water supply circulation pump is finely adjusted so that the hot water supply circulation pump becomes stable, the hot water temperature can be quickly adjusted and stabilized with respect to the flow rate change, and the hot water temperature becomes higher or lower than the predetermined temperature (overshoot) , Anda Shoot) can be prevented.

  Further, by opening the hot water storage tank to the atmosphere, it is possible to prevent pressure from being applied to the tank.

  Further, by using an electric heater as means for boiling the hot water in the hot water storage tank, the boiling operation can be performed in a short time.

  Further, by using a heat pump type heating device as means for boiling hot water in the hot water storage tank, the boiling operation can be performed at low cost.

  Hereinafter, an embodiment of a method for operating an electric water heater according to the present invention will be described with reference to the drawings.

The electric water heater applied to this electric water heater operating method is an electric water heater provided with a hot water heat exchanger 3 for indirectly heating the tap water in the water supply pipe 1 with hot water in the hot water storage tank 2. 3 is provided with a hot water flow rate sensor 4 on the secondary side 3b, and temperature sensors 5 to 8 are provided at the inlet and outlet of the primary side 3a and the secondary side 3b of the hot water supply heat exchanger 3, respectively.
Then, immediately after the start of hot water supply or immediately after the hot water supply flow rate sensor 4 detects a flow rate change of a certain amount or more, the necessary heat amount is calculated based on the hot water supply temperature set value, the hot water supply flow rate sensor 4 and the values of the temperature sensors 5-8. Based on this calculation result, the hot water supply circulation pump 31 is operated at a predetermined rotational speed to bring the primary side 3a of the hot water supply heat exchanger 3 into a state close to the optimum circulation amount, and then the secondary side of the hot water supply heat exchanger The flow rate of the hot water supply circulation pump 31 is adjusted so that the outlet temperature of 3b becomes a predetermined temperature.

In FIG. 1, one Example of the operating method of the electric water heater of this invention is shown.
For hot water supply, hot water in the upper part of the hot water storage tank 2 is led out by the hot water circulation pump 31 and returned to the lower part of the tank through the hot water supply heat exchanger 3, and the tap water in the water supply pipe 1 is passed through the hot water supply heat exchanger 3 to a predetermined temperature. This is done by heating to

Immediately after the start of hot water supply, the measured values of the temperature sensors 5 to 8 at the inlet and outlet of the hot water flow rate sensor 4 and the primary side 3a and secondary side 3b of the hot water supply heat exchanger 3 are detected, and the heat exchange amount of the hot water supply heat exchanger secondary side 3b Calculate
For example, when the hot water set temperature is 40 ° C., the secondary inlet temperature of the hot water heat exchanger 3 is 10 ° C., and the hot water flow rate sensor 4 is 12 L / min, the heat exchange amount of the hot water heat exchanger secondary side 3b is (40−10) × 12 × 60 = 21,600 kcal / hr.
Here, when the primary side inlet temperature of the hot water supply heat exchanger 3 is 80 ° C. and the outlet temperature is 15 ° C., the required flow rate of the hot water supply heat exchanger primary side 3a is 21600 / (80-15) /60=5.5L. / Min.
Therefore, immediately after the start of hot water supply, the hot water supply circulation pump 31 is operated at a rotational speed at which the flow rate is 5.5 L / min. Thereafter, for example, the flow rate of the hot water supply circulation pump 31 is adjusted so as to reach a predetermined temperature after 2 seconds. As a result, the hot water supply temperature can be increased to near the predetermined temperature immediately after the start of hot water supply, so that the time required to reach the predetermined temperature can be shortened.

On the other hand, when the flow rate changes suddenly, for example, when the flow rate changes from 12 L / min to 4 L / min, temperature sensors 5 to 8 at the inlet and outlet of the hot water supply flow rate sensor 4 and the hot water supply heat exchanger 3 on the primary side 3a and the secondary side 3b. Is measured, and the heat exchange amount of the hot water supply heat exchanger secondary side 3b is calculated.
At this time, for example, when the hot water supply set temperature is 40 ° C., the secondary inlet temperature of the hot water supply heat exchanger 3 is 10 ° C., and the hot water supply flow rate sensor 4 is 4 L / min, the heat of the hot water supply heat exchanger secondary side 3b The exchange amount is (40−10) × 4 × 60 = 7200 kca1 / hr.
Here, when the primary side inlet temperature of the hot water supply heat exchanger 3 is 80 ° C. and the outlet temperature is 15 ° C., the necessary flow rate of the hot water supply heat exchanger primary side 3a is 7200 / (80-15) /60=1.8L. / Min.
Therefore, immediately after the flow rate fluctuation is detected, the post-hot water supply circulation pump 31 is operated at a rotational speed at which the flow rate is 1.8 L / min. Thereafter, for example, the flow rate of the hot water supply circulation pump 31 is adjusted so as to reach a predetermined temperature after 2 seconds. As a result, the overshoot that occurs when the flow rate is reduced immediately after the flow rate fluctuation can be reduced, and the time until the hot water supply temperature reaches a predetermined temperature can be shortened.

Thus, the operation method of the electric water heater of the present embodiment is as follows. In the electric water heater provided with the hot water heat exchanger 3 for indirectly heating the tap water in the water supply pipe 1 with the hot water in the hot water storage tank 2, the hot water heat exchanger 3 is provided. The hot water supply flow rate sensor 4 is provided on the secondary side 3b of the hot water supply, and temperature sensors are provided at the inlets and outlets of the primary side 3a and the secondary side 3b of the hot water supply heat exchanger 3, respectively. 4 and the value of each temperature sensor, the required heat quantity is calculated, and the hot water supply circulation pump 31 is operated at a predetermined rotational speed based on the calculation result, whereby the primary side 3a of the hot water supply heat exchanger 3 is optimally circulated. Since the flow rate of the hot water supply circulation pump 31 is adjusted so that the outlet temperature of the hot water supply heat exchanger secondary side 3b becomes a predetermined temperature after the state close to the quantity is reached, first, the primary side of the hot water supply heat exchanger 3 Optimal circulation of 3a , The flow rate of the hot water supply circulation pump 31 can be finely adjusted so that the hot water supply temperature becomes a predetermined temperature, thereby shortening the time from the start of hot water supply until the hot water reaches a predetermined temperature. be able to.
In addition, even when the flow rate changes suddenly, the primary side 3a of the hot water supply heat exchanger 3 after the change is brought to a state close to the optimum circulation amount, and then the hot water supply circulation pump 31 is set so that the hot water supply temperature becomes a predetermined temperature. Since the flow rate is finely adjusted, it is possible to achieve quick response and stabilization of the hot water supply temperature with respect to changes in the flow rate, and to prevent the temperature from becoming higher or lower than the predetermined temperature.

  The hot water storage tank 2 is opened to the atmosphere so that no pressure is applied to the tank, and an electric heater or a heat pump type heating device (illustrated) is used as a means for boiling the hot water in the hot water storage tank 2. By using (omitted), the boiling operation can be performed in a short time or at low cost.

  As mentioned above, although the operating method of the electric water heater of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, The structure described in the Example is combined suitably. For example, the configuration can be changed as appropriate without departing from the spirit of the invention.

  As described above, the operation method of the electric water heater according to the present invention is that the hot water supply temperature is set to the predetermined temperature after the hot water supply circulation pump is operated at a predetermined rotation number immediately after the start of hot water supply or when there is a flow rate change exceeding a certain flow rate. Since the flow rate of the hot water supply circulation pump is adjusted as described above, it is possible to achieve quick response and stabilization of the hot water supply temperature with respect to the flow rate change, and it can be used widely and suitably for general-purpose electric water heater applications.

It is a circuit diagram which shows one Example of the operating method of the electric water heater of this invention. It is a circuit diagram which shows the operating method of the conventional electric water heater.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water supply piping 2 Hot water storage tank 3 Hot water supply heat exchanger 3a Primary side 3b Secondary side 31 Hot water circulation pump 4 Hot water supply flow sensor 5 Temperature sensor 6 Temperature sensor 7 Temperature sensor 8 Temperature sensor

Claims (5)

In the operation method of an electric water heater with a hot water supply heat exchanger that indirectly heats the tap water in the hot water supply pipe with hot water in the hot water storage tank, a hot water supply flow sensor is provided on the secondary side of the hot water heat exchanger and hot water heat exchange is performed. Temperature sensors are provided at the primary side inlet and secondary side entrance, respectively, and immediately after the start of hot water supply, the required heat quantity is calculated based on the hot water temperature set value, the hot water flow rate sensor, and the values of each temperature sensor. Based on the above, the hot water circulation pump is operated at a predetermined rotational speed to bring the primary side of the hot water heat exchanger close to the optimum circulation amount, and the outlet temperature on the secondary side of the hot water heat exchanger is set to a predetermined temperature. adjust the flow rate of the hot water supply circulation pump such that,
When the hot water flow rate sensor detects a change in the flow rate above a certain amount, immediately after that, the required heat quantity is calculated based on the hot water temperature setting value, the hot water flow rate sensor, and the values of each temperature sensor, and the hot water circulation is based on this calculation result. By operating the pump at a predetermined number of revolutions, the primary side of the hot water heat exchanger is brought close to the optimum circulation amount, and then the outlet temperature of the secondary side of the hot water heat exchanger becomes a predetermined temperature. An operation method of an electric water heater , characterized by adjusting a flow rate of a circulation pump . 2. The method for operating an electric water heater according to claim 1, wherein the hot water storage tank is opened to the atmosphere. The method for operating an electric water heater according to claim 1 or 2, wherein an electric heater is used as means for boiling the hot water in the hot water storage tank. The method of operating an electric water heater according to claim 1, 2 or 3, wherein a heat pump type heating device is used as means for boiling hot water in the hot water storage tank. In an electric water heater provided with a hot water heat exchanger that indirectly heats tap water in the hot water supply tank with hot water in the hot water storage tank, a hot water flow sensor is provided on the secondary side of the hot water heat exchanger, and the primary water heater heat exchanger A temperature sensor is provided at each of the side entrance and the secondary side entrance, and immediately after the start of hot water supply, the required amount of heat is calculated based on the set value of the hot water supply temperature, the hot water flow rate sensor, and each temperature sensor. By operating the hot water supply circulation pump at a predetermined number of revolutions, the primary side of the hot water heat exchanger is brought into a state close to the optimum circulation amount, and the outlet temperature of the secondary side of the hot water heat exchanger becomes a predetermined temperature. Adjust the flow rate of the hot water circulation pump,
When the hot water flow rate sensor detects a change in the flow rate above a certain amount, immediately after that, the required heat quantity is calculated based on the hot water temperature setting value, the hot water flow rate sensor, and the values of each temperature sensor, and the hot water circulation is based on this calculation result. By operating the pump at a predetermined number of revolutions, the primary side of the hot water heat exchanger is brought close to the optimum circulation amount, and then the outlet temperature of the secondary side of the hot water heat exchanger becomes a predetermined temperature. An electric water heater characterized by adjusting the flow rate of the circulation pump.

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