JP2019023526A - Hot water storage type water heater - Google Patents

Abstract

To accurately determine heating without water.SOLUTION: A hot water storage type water heater for heating hot water flowing into a tank with a heater and supplying the hot water includes: a first determination section for determining presence and absence of a temperature boundary layer formed in the tank by the hot water heated by the heater and the hot water flowing into the tank; and a second determination section for determining that heating without water by the heater occurs when the temperature boundary layer is not detected by the first determination section even if electric power is supplied to the heater.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hot water storage type water heater.

  2. Description of the Related Art Conventionally, there is known a hot water storage type hot water heater that determines an empty-running state when a temperature increase rate in a tank detected by a temperature sensor is larger than a threshold value. However, even if the air-fed state does not occur, it is determined as the air-fed state if the temperature suddenly increases for some reason.

  For example, when hot water boiled in a tank is intermittently discharged and water is replenished in the tank accordingly, a boundary layer between hot water (high temperature) and water (low temperature) ( Temperature boundary layer). If this temperature boundary layer occurs in the vicinity of the temperature sensor during the boiling operation, the detected temperature detected by the temperature sensor may become unstable and rapidly increase. For this reason, the hot water storage type hot water heater has a problem that, when the rate of temperature increase due to this rapid rise exceeds a threshold value, it is erroneously determined to be in an empty state.

  Therefore, Patent Document 1 uses the fact that there is a difference between the timing of temperature rise by air blowing and the timing of temperature rise by the temperature boundary layer, and based on the temperature rise rate in the tank during a predetermined period. A method of determining is disclosed.

  Specifically, the temperature rise in the tank caused by emptying occurs at an early stage after the boiling operation, whereas the temperature rise caused by the temperature boundary layer is considerably increased from the start of the boiling operation. Occurs after time has passed. Therefore, in the hot water storage type hot water heater described in Patent Document 1, the determination of emptying is performed only during a certain time (limited time) from the start of the boiling operation.

JP 2017-9184 A

  However, for example, when a low-capacity hot water storage tank is used or a high-output heater is used for boiling, the temperature rise caused by the temperature boundary layer may occur at a fast stage after the boiling operation. . For this reason, there may be a case where the temperature rise caused by the temperature boundary layer is erroneously determined to be caused by emptying.

  This invention is made | formed in view of such a situation, The objective is to provide the hot water storage type | formula water heater which can determine emptying with high precision.

  One aspect of the present invention is a hot water storage water heater that heats and supplies hot water that has flowed into a tank with a heater, and the hot water that has been heated by the heater and the hot water that has flowed into the tank into the tank. A first determination unit that determines the presence or absence of a temperature boundary layer to be formed, and if the temperature boundary layer is not detected by the first determination unit even when the heater is energized, an air blown by the heater occurs. It is a hot water storage type water heater characterized by including the 2nd judgment part judged to be.

  One aspect of the present invention is the above-described hot water storage type water heater, wherein the tank has a structure in which hot water heated by the heater flows out from the upper part and new hot water flows in from the lower part.

  One aspect of the present invention is the above-described hot water storage type water heater, further comprising a plurality of temperature detection units provided in a height direction of the tank, wherein the first determination unit is detected by each of the temperature detection units. The presence or absence of the temperature boundary layer is detected based on the measured temperature.

  One aspect of the present invention is the above-described hot water storage type water heater, wherein the first determination unit is configured such that when the temperature increase rate of the temperature detected by each of the temperature detection units is equal to or greater than a predetermined threshold value, It is determined that the temperature boundary layer is not formed.

  As described above, according to the present invention, it is possible to accurately determine idling.

It is a figure which shows an example of schematic structure of the hot water storage type water heater A which concerns on one Embodiment of this invention. It is a schematic block diagram of the control apparatus 17 which concerns on one Embodiment of this invention. It is a flowchart of the operation | movement of the idling prevention control which concerns on one Embodiment of this invention. It is a figure explaining the effect by the airing prevention control which concerns on one Embodiment of this invention.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention. In the drawings, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted. In addition, the shape and size of elements in the drawings may be exaggerated for a clearer description.

Hereinafter, a hot water heater according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a schematic configuration of a hot water storage water heater A according to an embodiment of the present invention.

  The hot water storage type water heater A includes a water supply pipe 1, a first bypass pipe 2, a hot water supply pipe 3, a mixing valve 4, a second bypass pipe 5, a filter 6, a check valve 7, a first temperature detection unit 8, and a first electromagnetic valve. 9, the 2nd solenoid valve 10, the 2nd temperature detection part 11, the cutoff valve 12, the drain plug 13, the tank 14, the heater 15, the 3rd temperature detection part 16, and the control apparatus 17 are provided.

  The water supply pipe 1 is connected to a tank 14. Thereby, the water which circulated through the water supply pipe 1 is supplied into the tank 14.

The first bypass pipe 2 is branched from the first branch portion 30 of the water supply pipe 1 and connected to the mixing valve 4. Specifically, one end of the first bypass pipe 2 communicates with the first branch portion 30 of the water supply pipe 1 and the other end communicates with the mixing valve 4.
One end of the hot water supply pipe 3 communicates with the upper part of the tank 14, and the other end communicates with the automatic water tap 100.

  The mixing valve 4 is provided in the middle of the hot water supply pipe 3. A first bypass pipe 2 branched from the water supply pipe 1 is communicated with the mixing valve 4. Thereby, in the mixing valve 4, the water supplied from the water supply pipe 1 and the hot water supplied from the hot water supply pipe 3 are mixed. In addition, an automatic temperature controller such as a thermostat (not shown) is provided inside the mixing valve 4. Therefore, the mixing ratio of hot water is controlled by the automatic temperature controller so that the hot water (mixed water) after mixing has a predetermined temperature (for example, 38 ° C. to 42 ° C.) suitable for use by the user or the like.

  The second bypass pipe 5 is branched from the second branch portion 31 of the water supply pipe 1 and connected to the hot water supply pipe 3 between the mixing valve 4 and the automatic water tap 100. Specifically, one end of the second bypass pipe 5 is connected to the second branch portion 31 of the water supply pipe 1, and the other end is connected to the hot water supply pipe 3 between the mixing valve 4 and the automatic water tap 100. The second branch portion 31 is provided on the upstream side of the first branch portion 30.

The filter 6 is provided on the upstream side of the second branch portion 31 in the water supply pipe 1. The filter 6 removes dust from the water flowing through the water supply pipe 1.
The check valve 7 is provided on the upstream side of the second branch portion 31 in the water supply pipe 1. The check valve 7 prevents the backflow of water flowing through the water supply pipe 1.

  The first temperature detection unit 8 is provided on the upstream side of the second branch portion 31 in the water supply pipe 1. The first temperature detection unit 8 detects the temperature of the water flowing through the water supply pipe 1 and transmits the detection result to the control device 17.

  The first solenoid valve 9 is provided in the water supply pipe 1 between the first branch part 30 and the second branch part 31 and opens or closes the path of the water supply pipe 1. The first electromagnetic valve 9 is controlled to be in an open state or a closed state by the control device 17.

  The second electromagnetic valve 10 is provided in the second bypass pipe 5 and opens or closes the path of the second bypass pipe 5. The second electromagnetic valve 10 is controlled to be in an open state or a closed state by the control device 17.

  The second temperature detector 11 is provided on the downstream side of the mixing valve 4 in the hot water supply pipe 3. The second temperature detector 11 detects the temperature of the mixed water supplied from the mixing valve 4 to the automatic faucet 100 and transmits the detection result to the control device 17.

  The shutoff valve 12 is provided in the hot water supply pipe 3 between the tank 14 and the mixing valve 4. The shutoff valve 12 prevents hot water in the tank 14 from flowing out of the tank 14 by natural convection.

  The drain plug 13 is provided on the downstream side of the water supply pipe 1. The drain plug 13 is opened when it is desired to drain water in the tank 14 during maintenance or the like, and the water in the tank 14 is drained.

  The tank 14 is configured as a hollow can body made of, for example, a metal material, and stores water flowing in from the water supply pipe 1.

  The heater 15 is provided in the tank 14. The heater 15 heats the water in the tank 14 to a predetermined temperature based on the control of the control device 17.

  A plurality of third temperature detectors 16 are provided in the tank 14. Specifically, the plurality of third temperature detectors 16 are, for example, thermistors provided at predetermined intervals in the height direction of the tank 14.

  Each third temperature detector 16 detects the temperature in the tank 14 corresponding to the installation position. Each third temperature detection unit 16 transmits the detected temperature to the control device 17. In the present embodiment, a case where two third temperature detection units 16 are provided in the height direction of the tank 14 will be described, but the present invention is not limited to this, and two or more third temperature detection units 16 are provided. May be provided in the height direction of the tank 14. In the following description, of the two third temperature detectors 16, the third temperature detector 16 provided on the lower side in the height direction of the tank 14 is referred to as a “lower temperature sensor 16 a” and is The provided third temperature detector 16 is referred to as an “upper temperature sensor 16b”. The lower temperature sensor 16 a is provided on the surface of the tank 14 in the vicinity of the heater 15.

  The control device 17 controls each of the first electromagnetic valve 9 and the second electromagnetic valve 10 to an open state or a closed state. Specifically, when the hot water storage type water heater A detects an object such as a hand when the detection sensor provided in the automatic faucet 100 detects the hot water heater A during normal hot water operation, the detection result is transmitted to the control device 17. . Therefore, the control device 17 controls the first electromagnetic valve 9 to be in an open state when the detection sensor detects an object such as a hand during a normal hot water operation. As a result, the mixed water is supplied from the automatic faucet 100, and an amount of water corresponding to the supplied mixed water flows into the tank 14 through the water supply pipe 1.

  The control device 17 always controls the second electromagnetic valve 10 to be in a closed state while the hot water heater A is in the hot water operation. On the other hand, the control device 17 controls the second electromagnetic valve 10 to be in an open state when the hot water heater A is not in the hot water operation and when high temperature hot water is detected. Thereby, the control device 17 mixes water with hot hot water flowing through the hot water supply pipe 3 at the time of a power failure or when the mixing valve 4 fails, so that the hot hot water is supplied from the automatic faucet 100. To prevent it. The control device 17 can detect that the hot water in the hot water supply pipe 3 is at a high temperature based on the detection signal from the second temperature detection unit 11 (the high temperature hot water detection).

The control device 17 performs a so-called boiling operation in which hot water stored in the tank 14 is heated to a boiling temperature by energizing the heater 15 with power from a power source D (for example, a commercial power source). This boiling operation is executed in each of a plurality of time zones within a predetermined period. For example, the control device 17 divides a day into a plurality of time zones, and performs a boiling operation for each of the divided time zones.
Here, the control device 17 performs the idling prevention control during the boiling operation. The idling prevention control is control for determining whether or not idling is performed during the boiling operation and stopping or continuing the boiling operation according to the determination result. In addition, idling means that the heater 15 is energized with no hot water in the tank 14.
Below, the emptying prevention control of the control apparatus 17 which concerns on this embodiment is demonstrated concretely.

  Below, the structure of the control apparatus 17 which concerns on this embodiment is demonstrated using FIG. FIG. 2 is a schematic configuration diagram of the control device 17 according to the present embodiment.

  As shown in FIG. 2, the control device 17 includes a heater relay 18, an acquisition unit 19, a storage unit 20, a first determination unit 21, a second determination unit 22, and a control unit 23.

  The heater relay 18 is electrically connected between the power source D and the heater 15. The heater relay 18 is opened and closed by the control unit 23. That is, when the contact of the heater relay 18 is controlled to be closed, the power from the power source D is supplied to the heater 15. Thereby, the heater 15 generates heat. On the other hand, when the contact of the heater relay 18 is controlled to be in the open state, the supply of power from the power source D to the heater 15 is stopped. Thereby, the heat generation of the heater 15 is stopped.

  The acquisition unit 19 acquires the temperature T in the tank 14 from each of the lower temperature sensor 16a and the upper temperature sensor 16b at regular intervals. And the acquisition part 19 stores each temperature T acquired in the memory | storage part 20 as a data log.

  The storage unit 20 includes a first storage unit 211 and a second storage unit 212.

In the first storage unit 211, the temperature T ₁ detected by the lower temperature sensor 16 a when the heater 15 is energized during the boiling operation is stored in a data log (hereinafter referred to as “lower empty determination temperature log”). It is stored as. The number of data of the temperature T ₁ stored as the lower empty determination temperature log in the first storage unit 211 is set to the latest N ₁ . Thus, with the latest N ₁ pieces of temperatures T ₁ in the first storage section 211 is stored, when acquiring a new temperature T ₁ of the lower temperature sensor 16a is lower boil-dry judgment temperature It deletes the oldest temperatures T ₁ of the log, is stored the new temperature T ₁ of the first storage unit 211 as the lower air-fired determination temperature log.

In the second storage unit 212, the temperature T ₂ detected by the upper temperature sensor 16 b when the heater 15 is energized during the boiling operation is referred to as a data log (hereinafter referred to as “upper empty determination temperature log”). ). The second number of data in the temperature T ₂ which is stored in the storage unit 212 as the upper air-fired judgment temperature log is set to _two latest N. Therefore, in the state where the latest N ₂ temperatures T ₂ are stored in the second storage unit 212, when a new temperature T ₂ is acquired from the upper temperature sensor 16 b, the upper empty determination temperature log of deletes the oldest temperature T _2, are stored in the new temperature T ₂ as the upper air-fired determination temperature logs in the second storage unit 212. N ₂ and N ₁ may be the same value or different values.
The storage of the new temperature T _{1 in the} storage unit 20 as the lower empty determination temperature log and the new temperature T ₂ as the upper empty determination temperature log is referred to as “update”.

  The first determination unit 21 determines whether or not there is a temperature boundary layer formed in the tank 14 by the hot water heated by the heater 15 and the hot water flowing into the tank 14. The temperature boundary layer of the present embodiment is formed by hot water boiled in the tank 14 intermittently flowing out from the upper part of the tank 14 and new water flowing in from the lower part in the tank accordingly. . Accordingly, in the tank 14, hot hot water heated by the heater 15 (hereinafter referred to as “first hot water”) is stored above the temperature boundary layer, and before being heated by the heater 15. Low temperature hot water (hereinafter referred to as “second hot water”) is stored. Therefore, as a matter of course, the temperature of the first hot water is higher than that of the second hot water.

For example, the first determination unit 21 determines whether or not there is a temperature boundary layer formed in the tank 14 based on the temperatures detected by the lower temperature sensor 16a and the upper temperature sensor 16b. Specifically, the first determination unit 21 has a temperature increase rate of the temperature T ₁ detected by the lower temperature sensor 16a (hereinafter referred to as “first temperature increase rate”) _{equal to} or higher than a first threshold value T _1thr . There, and heating rate of the temperature T ₂ detected by the upper temperature sensor 16b (hereinafter, "second heating rate" referred.) If is the second threshold value T _2Thr above, the tank 14 It is determined that the temperature boundary layer is not formed.

When the first temperature rising rate is _{equal to} or higher than the first threshold T _1thr and the second temperature rising rate is _{equal to} or higher than the second threshold T _2thr , there is no region where the temperature is different in the tank 14. This means that no temperature boundary layer is formed in the tank 14.

On the other hand, when the first determination unit 21 is at least one of the case where the first temperature increase rate is less than the first threshold T _1thr and the case where the second temperature increase rate is less than the second threshold, It is determined that a temperature boundary layer is formed in the tank 14. For example, when the first temperature increase rate is _{equal to} or higher than the first threshold T _1thr and the second temperature increase rate is less than the second threshold, the first determination unit 21 sets a temperature boundary in the tank 14. It is determined that a layer is formed.
Note that the first threshold value T _1thr and the second threshold value T _2thr are temperature rising speeds when there is a possibility of emptying, and may be the same value, for example, or the second threshold value T _2thr may be the first threshold value T _2thr . A value lower than the threshold T _1thr may be used. Further, the first threshold T _1thr and the second threshold T _2thr can be changed according to the capacity of the tank 14 and the like.

The second determination unit 22 determines whether or not the heater 15 is aired. Specifically, even if the heater 15 is energized, if the first determination unit 21 does not determine that a temperature boundary layer has been formed, the second determination unit 22 generates air. It is determined that This is because the fact that the temperature boundary layer is not formed indicates that hot water is not stored in the tank 14.
Therefore, when the heater 15 is energized and the first determination unit 21 determines that the temperature boundary layer is formed, the second determination unit 22 determines that the air blown by the heater 15 has not occurred. .

The controller 23 controls energization to the heater 15 by opening and closing the contact of the heater relay 18. The control unit 23 stops energization of the heater 15 when it is determined by the second determination unit 22 that airing has occurred during the boiling operation.
On the other hand, the control unit 23 continues energization of the heater 15 when it is determined by the second determination unit 22 that no air heating has occurred during the boiling operation.

  Next, the operation of the idling prevention control of the control device 17 according to the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart of the operation of the airing prevention control according to the present embodiment.

  First, the controller 23 energizes the heater 15 by controlling the contact of the heater relay 18 to be closed. Thereby, the control apparatus 17 starts a boiling operation (step S101).

  When the boiling operation is started, the acquisition unit 19 has a lower empty determination temperature log stored in the first storage unit 211 and an upper empty determination temperature stored in the second storage unit 212. All logs are deleted (cleared) (step S102). This is because temperature data at the time of the previous boiling operation may remain in the first storage unit 211 and the second storage unit 212 in some cases.

Acquisition unit 19, the temperature _{T 1} of the tank 14 from the lower side temperature sensor 16a, the upper temperature sensor 16b acquires the temperature _{T 2} in the tank 14 (step S103). The acquisition unit 19, the temperatures T ₁ obtained by storing in the first storage unit 211 as the lower air-fired determination temperature log, updates the lower boil-dry judgment temperature log. Further, the acquisition unit 19, the temperature T ₂ obtained by storing in the second storage unit 212 as the upper air-fired judgment temperature log, updates the upper boil-dry judgment temperature log (step S104).

When the lower empty determination temperature log is updated, the first determination unit 21 extracts the minimum value T _1min of the lower empty determination temperature log stored in the first storage unit 211. The first determination unit 21, temperatures _{T 1} acquired in step S103 determines whether the minimum value _{T 1min} more (step S105).

The first determination unit 21, when the temperatures _{T 1} acquired in step S103 is determined to be less than the minimum value _{T min,} the process returns to step S102. On the other hand, the first determination unit 21, when the temperatures T ₁ acquired in step S103 is determined to be the minimum value T _1min above, the upper air-fired judgment temperature log stored in the second storage unit 212 The minimum value T _2min is extracted. The first determination unit 21, temperature _{T 2} obtained in step S103 determines whether the minimum value _{T 2min} more (step S106).

The first determination unit 21, when the temperature _{T 2} obtained in step S103 is determined to be less than the minimum value _{T 2min,} the process returns to step S102. On the other hand, the first determination unit 21, when the temperature _{T 2} obtained in step S103 is determined to be the minimum value _{T 2min} above determines whether or not the temperature _{T 1} is is retained temperature _{T off} more ( Step S107). Here, the heat retaining temperature T _off is a temperature for retaining hot water in the tank 14. If the temperature T ₂ is determined to be retained temperature T _off or by first determining section 21, the control unit 23 controls the contact of the heater relay 18 in an open state, current supply to the heater 15 To stop. Thereby, the boiling operation is completed (step S108).

On the other hand, the first determination unit 21, when it is determined that the temperature T ₁ is less than the retained temperature T _off, of the lower air-fired determination temperature log after the update stored in the first storage unit 211 The maximum value T _1max and the minimum value T _1min are extracted. The first determination unit 21, the maximum value _{T 1max} and minimum value difference value between _{T 1min} - determines whether (the maximum value _{T 1max} minimum _{T 1min)} is the first threshold value _{T 1Thr} above (Step S109) . This difference value (maximum value T _{1max −minimum} value T _1min ) corresponds to the first temperature increase rate described above.

If the first determination unit 21 determines that the difference value (maximum value T _{1max −minimum} value T _1min ) is less than the first threshold value T _1thr , the process returns to step 103. This is because there is no possibility of airing.

If the first determination unit 21 determines that the difference value (maximum value T _{1max −minimum} value T _1min ) is _{equal to} or greater than the first threshold value T _1thr , whether or not a temperature boundary layer is formed in the tank 14. Determine. This is because there is a possibility that the temperature rise in step S109 is caused by emptying, but it is possible to distinguish whether the temperature rise is caused by the temperature boundary layer or the temperature rise caused by the boiling operation. This is because there is not.

Specifically, the first determination unit 21 first, of the upper air-fired judgment temperature log after the update stored in the second storage unit 212, extracts the maximum value T _2max and minimum value T _2min. The first determination unit 21, the maximum value _{T 2max} and minimum difference value between _{T 2min} - determines whether (the maximum value _{T 2max} minimum _{T 2min)} is the second threshold value _{T 2Thr} above (Step S110) . Incidentally, the difference value (maximum value _{T 2max} - minimum _{T 2min)} corresponds to the second heating rate as described above.

The first determination unit 21, difference value - determined (maximum value _{T 2max} minimum _{T 2min)} is when it is judged less than the second threshold value _{T 2Thr} the temperature boundary layer is formed in the tank 14 To do. Therefore, the second determination unit 22 determines that no air-spreading has occurred, and returns to step S103.

On the other hand, the first determination unit 21, difference value (the maximum value _{T 2max} - minimum _{T 2min)} is when it is determined that the second threshold _{T 2Thr} or more, not the temperature boundary layer is formed in the tank 14 Is determined. Therefore, the second determination unit 22 determines that airing has occurred (step S111).

  When it is determined by the second determination unit 22 that the air blow has occurred, the control unit 23 controls the contact of the heater relay 18 to be in an open state, thereby stopping energization to the heater 15 ( Step S112).

  Next, the effect of the airing prevention control of this embodiment will be described with reference to FIG. FIG. 4 is a diagram for explaining the effect of the airing prevention control according to the present embodiment.

A conventional hot water storage type hot water heater uses a detection result of a temperature sensor (corresponding to the lower temperature sensor 16a according to the present embodiment) provided on the surface of the tank 14 in the vicinity of the heater 15 to raise the temperature in the tank 14. Measure the temperature rate. And the conventional hot water storage type water heater determines that it is empty when this measured temperature rising rate is larger than a threshold value (first threshold value T _{1thr according to} the present embodiment). However, in this method, if a temperature boundary layer occurs in the vicinity of the lower temperature sensor 16a during the boiling operation, the temperature detected by the lower temperature sensor 16a rapidly increases due to natural convection. For this reason, the conventional hot water storage type water heater erroneously determines that the temperature rises due to this rapid rise exceeds the first threshold value T _1thr as being empty.

On the other hand, when the temperature rising rate is _{equal to} or higher than the first threshold value T _1thr , the hot water storage water heater A is caused by emptying the temperature rising due to the temperature boundary layer by determining the presence or absence of the temperature boundary layer. It is possible to prevent erroneous determination that the temperature is rising.
For example, as shown in FIG. 4, in the hot water storage type water heater A, an upper temperature sensor 16 b is provided at a position above the lower temperature sensor 16 a in the height direction of the tank 14. The position where the upper temperature sensor 16b is provided is a position where, even if a temperature boundary layer occurs in the vicinity of the lower temperature sensor 16a during the boiling operation, there is no influence on the temperature increase rate detected by the upper temperature sensor 16b, or Even if there is, there is a position where the temperature rising rate is low to a level that is distinguishable as compared with the temperature rising rate in the vicinity of the lower temperature sensor 16a. Therefore, the second threshold value T _2thr is set in consideration of the above influence.

Here, when emptying occurs, the entire tank 14 rapidly rises, so that the temperature increase rate of the lower temperature sensor 16a becomes _{equal to} or higher than the first threshold value _T1thr, and the temperature increase rate of the upper temperature sensor 16b becomes the second threshold value. T 2 _thr or more. On the other hand, when the temperature boundary layer is formed in the vicinity of the lower temperature sensor 16a, the temperature increase rate of the lower temperature sensor 16a is _{equal to} or higher than the first threshold value _T1thr, and the temperature increase rate of the upper temperature sensor 16b is the second threshold value. T _is less than _2thr .

  Therefore, the hot water storage type water heater A can accurately determine the emptying by detecting the presence / absence of the temperature boundary layer based on the temperature increase rate detected by the lower temperature sensor 16a and the upper temperature sensor 16b. Can do.

  By the way, after determining a test energizing period as a method for determining airing different from the present embodiment (method for determining the presence or absence of airing), energizing the heater 15 in the tank 14 during the test energizing period (test energizing), A method is conceivable in which the test energization to the heater 15 is stopped and it is determined that the emptying has occurred when the temperature rise of the tank 14 due to residual heat exceeds a predetermined value. However, when this method is used, the hot water storage water heater performs the boiling operation when it is determined that the hot water heater is not empty in the emptying determination method based on the test energization. Therefore, in order to boil the hot water in the tank 14, the contact of the heater relay 18 is opened and closed by each of the test energization and the boiling operation, and the contact life of the heater relay 18 is reduced.

On the other hand, the hot water storage type water heater A of the present embodiment performs a process of determining whether or not there is an airing during the boiling operation, and if it is determined that no airing has occurred, the heater 15 is energized. without stopping, hot water in the tank 14 performs a heating operation until the heat retaining temperature T _off. Thus, hot water storage type water heater A is the opening and closing of the contacts of the heater relay 18 until hot water in the tank 14 is retained temperature T _off requires only once. Therefore, the hot water storage type water heater A can reduce the number of times the contacts of the heater relay 18 are opened and closed, and can suppress a decrease in the contact life of the heater relay 18.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

(Modification 1) In the above embodiment, when the second determination unit 22 determines that airing has occurred, the control device 17 indicates that airing has occurred, for example by using an indicator lamp. The notification is made by lighting, but is not limited to this. For example, when it is determined by the second determination unit 22 that airing has occurred, the control device 17 has an administrator who manages the hot water storage water heater A (or the hot water storage water heater A is introduced). You may notify to a communication terminal of a building manager) by wire or wireless. The communication terminal may be any terminal as long as it is a communicable terminal, such as a mobile phone such as a smartphone, a tablet terminal, and a PC (Personal Computer).

(Modification 2) In the above embodiment, the case where the hot water storage type water heater A is the first stop type has been described, but the present invention is not limited to this. For example, the hot water storage type water heater A may be a former stop type.

(Modification 3) In the above-described embodiment, the hot water storage type water heater A performs the idling prevention control when the heater 15 is energized, but the present invention is not limited to this. For example, the hot water storage type water heater A may determine whether or not there is a temperature boundary layer by stopping energization of the heater 15 when the temperature increase rate of the lower temperature sensor 16a becomes _{equal to} or higher than the first threshold value _T1thr. .

  As described above, the hot water storage water heater A is the first determination unit 21 that determines whether or not there is a temperature boundary layer formed in the tank 14 by the hot water heated by the heater 15 and the hot water flowing into the tank 14. And a second determination unit 22 that determines that the heater is empty when the temperature determination layer is not detected by the first determination unit even when the heater 15 is energized. Thereby, the hot water storage type water heater A can suppress the decrease in the contact life of the heater relay 18 and can accurately determine idling.

  In addition, the hot water storage type water heater A determines the presence or absence of airing according to the temperature increase rate in the tank 14 after the energization of the heater 15 is interrupted. Therefore, the hot water storage type water heater A can easily distinguish between the temperature rise caused by the temperature boundary layer and the temperature rise due to air blowing.

Moreover, the hot water storage type water heater A sets the first threshold value T _1thr and the second threshold value T _2thr to values lower than the threshold values at which the over-rise prevention device operates. Thereby, the hot water storage type hot water heater A can detect the emptying more accurately before the excessive rise prevention device operates.

  Moreover, the tank 14 of the hot water storage type water heater A has a structure in which hot water heated by the heater 15 flows out from the upper part and new hot water flows in from the lower part. As a result, a temperature boundary layer is easily formed in the tank 14 of the hot water heater A, and the present invention becomes more useful.

  The hot water storage type water heater A further includes a third temperature detection unit 16 provided in a plurality in the height direction of the tank 14. And based on the temperature detected by the hot water storage water heater A and each 3rd temperature detection part 16, the presence or absence of a temperature boundary layer is detected. Thereby, the hot water storage type hot water heater A can accurately determine whether or not it is empty. In addition, the installation position of each 3rd temperature detection part 16 should just differ in the position of the height direction of the tank 14, respectively, The position of the horizontal direction of the tank 14 is not specifically limited. Accordingly, the horizontal positions of the third temperature detectors 16 provided in the height direction of the tank 14 may be the same or different from each other.

  Further, the hot water storage type hot water heater A determines that the emptying by the heater 15 has occurred when the temperature increase rate of the temperature detected by each third temperature detection unit 16 exceeds a predetermined threshold value. Thereby, the hot water storage type hot water heater A can accurately determine whether or not it is empty.

A Hot water heater 14 Tank 15 Heater 16 Third temperature detection unit 17 Controller 18 Heater relay 19 Acquisition unit 20 Storage unit 21 First determination unit 22 Second determination unit 23 Control unit

Claims (4)

A hot water heater that heats hot water flowing into the tank by a heater and supplies hot water,
A first determination unit for determining the presence or absence of a temperature boundary layer formed in the tank by hot water heated by the heater and hot water flowing into the tank;
A second determination unit that determines that the heater has generated air if the temperature determination layer is determined not to be formed by the first determination unit even when the heater is energized;
A hot water storage type water heater characterized by comprising.   The hot water storage water heater according to claim 1, wherein the tank has a structure in which hot water heated by the heater flows out from an upper part and new hot water flows in from a lower part. A plurality of temperature detection units provided in the height direction of the tank;
The hot water storage water heater according to claim 1 or 2, wherein the first determination unit detects the presence or absence of the temperature boundary layer based on the temperature detected by each of the temperature detection units.   The said 1st determination part determines with the said temperature boundary layer not being formed, when the temperature increase rate of the temperature detected by each said temperature detection part is more than a predetermined threshold value. No hot water heater.

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