HOT WATER SUPPLY SYSTEM

Abstract

A control part of a hot water supply system is configured as follows. When a hot water flow rate in a hot water circulation path is equal to or greater than a predetermined reference flow rate when the pump is driven and an immediate hot water supply operation is being performed, and duration of this state is equal to or longer than a predetermined first time, the control part determines that a hot water supply terminal is in an opened state and stops driving of the pump. When the pump is driven during setting of a test operation mode of the hot water supply system, the hot water flow rate in the hot water circulation path at that time is detected, and the reference flow rate can be determined based on a detected value of the hot water flow rate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Japan Application No. 2023-183716, filed on Oct. 26, 2023. The entirety of the above-described patent application is hereby incorporated by reference herein and made a part of the present specification.

BACKGROUND

Technical Field

The disclosure relates to a hot water supply system in which an immediate hot water supply operation is possible.

In the present specification, “immediate hot water supply operation” refers to an operation for circulating and retaining in advance heated hot water at a predetermined temperature or higher in a hot water flow path connected to a hot water supply terminal in a hot water supply system so that, when the hot water supply terminal is opened, hot water at the predetermined temperature or higher can be immediately flowed out from the hot water supply terminal.

Related Art

The present applicant has previously proposed, as a specific example of a conventional hot water supply system, one described in FIG. 11 and FIG. 13 of Patent Document 1.

The conventional hot water supply system includes a water heater capable of heating hot water and a pump configured as a separate device from the water heater. The pump is provided in an external hot water flow path connected to an outside (outside of an outer case) of the water heater. When a hot water supply terminal is in a closed state, by driving the pump, an immediate hot water supply operation is possible in which hot water in the external hot water flow path is sent into an inlet of the water heater and is circulated through a predetermined hot water circulation path. During the immediate hot water supply operation, since the hot water passes through a hot water heating section inside the water heater, the hot water in the hot water circulation path can be heated to a predetermined temperature or higher in advance. Accordingly, when the hot water supply terminal is opened, it is possible to immediately discharge heated hot water at the predetermined temperature or higher from the hot water supply terminal.

In such a hot water supply system, the pump is not incorporated into (inside the outer case of) the water heater. Hence, the pump can be, for example, a locally procured item prepared separately from the water heater, thus providing excellent flexibility in system construction.

However, in the related art, there is still room for improvement as described below.

That is, during a period during which the pump is driven and the immediate hot water supply operation is performed, when the hot water supply terminal is opened, it is desirable to accurately detect this situation and stop driving the pump. The reason is that, from various perspectives, it is unfavorable to continue driving of the pump even though the hot water supply terminal is in the opened state and hot water supply to the hot water supply terminal is being performed.

Accordingly, in Patent Document 1, during the immediate hot water supply operation, an actual hot water flow rate (flow rate per unit time) in the hot water circulation path is measured using a flow sensor, and the actual hot water flow rate is stored in advance as an actual flow rate value in an appropriate control part. This actual flow rate value is a value when the hot water supply terminal is in a fully closed state. On the other hand, during the immediate hot water supply operation, when a flow rate of hot water in the hot water circulation path is equal to or greater than the actual flow rate value, it is determined that the hot water supply terminal is in the opened state, and driving of the pump is stopped.

However, according to such a configuration, to reliably detect that the hot water supply terminal is in the opened state during the immediate hot water supply operation, it is necessary that the immediate hot water supply operation has been repeatedly executed beforehand and an appropriate value has been obtained as the actual flow rate value. Accordingly, for example, in an initial stage of start of use of the hot water supply system, there is a problem that it is difficult to appropriately detect that the hot water supply terminal is in the opened state during the immediate hot water supply operation.

Compared to the case where the pump is incorporated inside the water heater, in the case where the pump is provided outside the water heater, it is relatively difficult to distinguish whether a change in the flow rate of the hot water in the hot water circulation path during the immediate hot water supply operation is due to the opened state of the hot water supply terminal or due to a change in the driving state of the pump.

[Patent Document 1] Japanese Patent Laid-open No. 2021-1712

[Patent Document 2] Japanese Patent Laid-open No. 2021-85549

[Patent Document 3] Japanese Patent No. 5505129

[Patent Document 4] Japanese Patent Laid-open No. 2021-183890

[Patent Document 5] Japanese Patent No. 3810187

SUMMARY

A hot water supply system provided according to a first aspect of the disclosure includes: a water heater, including an internal hot water flow path connected to a water inlet and a hot water outlet, as well as a hot water heating section provided in the internal hot water flow path, and enabling hot water entered from the water inlet to be heated before reaching the hot water outlet; an external hot water flow path, arranged outside the water heater, and enabling hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal; a pump for hot water circulation, configured as a separate device from the water heater, provided in the external hot water flow path, and enabling an immediate hot water supply operation in which hot water is circulated in a predetermined hot water circulation path of the external hot water flow path and the internal hot water flow path when the hot water supply terminal is in a closed state; a control part, capable of executing on/off control of driving of the pump; and a flow sensor, for detecting a hot water flow rate in the hot water circulation path during the immediate hot water supply operation. The control part is configured to, if the hot water flow rate in the hot water circulation path is equal to or greater than a predetermined reference flow rate when the pump is driven and the immediate hot water supply operation is being performed, and duration of this state is equal to or longer than a predetermined first time, determine that the hot water supply terminal is in an opened state and stop driving of the pump. When the pump is driven during setting of a test operation mode of the hot water supply system, the hot water flow rate in the hot water circulation path at that time is detected, and the reference flow rate can be determined based on a detected value of the hot water flow rate.

A hot water supply system provided according to a second aspect of the disclosure includes: a water heater, including an internal hot water flow path connected to a water inlet and a hot water outlet, as well as a hot water heating section provided in the internal hot water flow path, and enabling hot water entered from the water inlet to be heated before reaching the hot water outlet; an external hot water flow path, arranged outside the water heater, and enabling hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal; a pump for hot water circulation, configured as a separate device from the water heater, provided in the external hot water flow path, and enabling an immediate hot water supply operation in which hot water is circulated in a predetermined hot water circulation path of the external hot water flow path and the internal hot water flow path when the hot water supply terminal is in a closed state; a control part, capable of executing on/off control of driving of the pump; a flow sensor, for detecting a hot water flow rate in the hot water circulation path during the immediate hot water supply operation; and a temperature sensor in the hot water circulation path, for detecting a hot water temperature on an inlet side of the hot water heating section. The control part is configured to, if a temperature of hot water in the hot water circulation path does not rise to a predetermined first temperature or higher, determine that the hot water supply terminal is in an opened state and stop driving of the pump, despite a fact a cumulative flow rate of hot water in the hot water circulation path from start of the immediate hot water supply operation has reached a predetermined reference capacity set corresponding to a capacity of the hot water circulation path. When the immediate hot water supply operation is performed in a test operation mode of the hot water supply system, a hot water flow rate in the hot water circulation path from a point when delivery of heated hot water from the hot water heating section to the hot water circulation path is started until the heated hot water reaches the temperature sensor and a temperature detected by the temperature sensor rises to a predetermined second temperature or higher is obtained, and the predetermined reference capacity can be determined based on the hot water flow rate.

Other features and advantages of the disclosure will become more apparent from the following description of the embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory diagram illustrating an example of a hot water supply system according to the disclosure.

FIG. 2A is a schematic diagram illustrating a state of the hot water supply system illustrated in FIG. 1 during an immediate hot water supply operation; FIG. 2B is a schematic explanatory diagram illustrating a state during a test operation.

FIG. 3 is a schematic explanatory diagram of main parts illustrating another example of the hot water supply system according to the disclosure.

FIG. 4 is a flowchart illustrating an example (test operation mode) of an operation procedure executed in the hot water supply system illustrated in FIG. 1.

FIG. 5 is a flowchart illustrating another example (immediate hot water supply operation in normal operation mode) of an operation procedure executed in the hot water supply system illustrated in FIG. 1.

FIG. 6A is a schematic explanatory diagram illustrating another example of a hot water supply system (during normal operation) according to the disclosure; FIG. 6B is a schematic explanatory diagram illustrating a state of the hot water supply system illustrated in FIG. 6A during the immediate hot water supply operation.

FIG. 7 is a flowchart illustrating an example (immediate hot water supply operation in normal operation mode (non-test operation mode)) of an operation procedure executed in the hot water supply system illustrated in FIG. 6A and FIG. 6B.

DESCRIPTION OF THE EMBODIMENTS

The disclosure provides a hot water supply system in which, when a hot water supply terminal is opened during an immediate hot water supply operation, this situation can be accurately detected and control to stop driving of a pump for hot water circulation can be appropriately performed.

The disclosure employs the following technical means.

A hot water supply system provided according to a first aspect of the disclosure includes: a water heater, including an internal hot water flow path connected to a water inlet and a hot water outlet, as well as a hot water heating section provided in the internal hot water flow path, and enabling hot water entered from the water inlet to be heated before reaching the hot water outlet; an external hot water flow path, arranged outside the water heater, and enabling hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal; a pump for hot water circulation, configured as a separate device from the water heater, provided in the external hot water flow path, and enabling an immediate hot water supply operation in which hot water is circulated in a predetermined hot water circulation path of the external hot water flow path and the internal hot water flow path when the hot water supply terminal is in a closed state; a control part, capable of executing on/off control of driving of the pump; and a flow sensor, for detecting a hot water flow rate in the hot water circulation path during the immediate hot water supply operation. The control part is configured to, if the hot water flow rate in the hot water circulation path is equal to or greater than a predetermined reference flow rate when the pump is driven and the immediate hot water supply operation is being performed, and duration of this state is equal to or longer than a predetermined first time, determine that the hot water supply terminal is in an opened state and stop driving of the pump. When the pump is driven during setting of a test operation mode of the hot water supply system, the hot water flow rate in the hot water circulation path at that time is detected, and the reference flow rate can be determined based on a detected value of the hot water flow rate. According to such a configuration, the following may be achieved.

That is, when the pump is driven and the immediate hot water supply operation is being performed, when the hot water supply terminal is opened, the hot water flow rate in the hot water circulation path increases. With respect to this, according to the aforementioned configuration, when the hot water flow rate increases to be equal to or greater than the predetermined reference flow rate, and the duration of this state is equal to or longer than the predetermined first time, it is determined that the hot water supply terminal is in the opened state, and driving of the pump is stopped. Here, the reference flow rate is a value determined based on the detected value of the hot water flow rate obtained when the pump is actually driven during the test operation of the hot water supply system. Hence, it is possible to set the reference flow rate to an appropriate value corresponding to actual circumstances (actual specifications) of the hot water supply system. The reference flow rate can be obtained early at a stage of conducting the test operation of the hot water supply system. From an initial stage where a user actually uses and operates the hot water supply system after the test operation, the reference flow rate can be set to a value appropriately corresponding to the opened state of the hot water supply terminal during the immediate hot water supply operation. Accordingly, the configuration is preferable in view of solving a problem that the pump remains driven even after the hot water supply terminal is opened during the immediate hot water supply operation.

In the disclosure, preferably, in the case where driving of the pump during setting of the test operation mode is performed for a predetermined second time or longer, the control part executes processing for determining whether a fluctuation range of the detected value of the hot water flow rate detected during a period during which the driving of the pump during setting of the test operation mode is performed for the second time or longer is a normal value within a predetermined range. If the detected value is determined to be a normal value, the reference flow rate is determined based on the detected value; if the detected value is determined not to be a normal value, the reference flow rate is not determined based on the detected value, and the reference flow rate can be determined based on the detected value as a normal value obtained by repeating the processing for determining again thereafter.

According to such a configuration, the following may be achieved.

That is, for example, in an initial stage of the test operation mode, due to factors such as residual air in the hot water circulation path, the hot water flow rate during driving of the pump may be unstable and may significantly fluctuate. The detected value of the hot water flow rate in such a case is determined not to be a normal value, and determining the reference flow rate based on the detected value is avoided. If the state of each part of the hot water supply system stabilizes and the fluctuation range of the detected value of the hot water flow rate in the hot water circulation path decreases, the reference flow rate is determined based on the detected value of the hot water flow rate. Accordingly, the reference flow rate can be reliably set to an appropriate value corresponding to the original specifications of the hot water supply system.

In the disclosure, preferably, a main water heater and a sub water heater are provided as the water heater, the main water heater being preferentially operated for a hot water supply load, the sub water heater being complementarily operated when an insufficient amount of heat is supplied by the main water heater alone. When the immediate hot water supply operation is performed, only the main water heater performs heating of hot water circulating through the hot water circulation path, while the sub water heater maintains a state of being prohibited from heating hot water, and complementary operation of the sub water heater is not allowed unless driving of the pump of the main water heater is stopped.

According to such a configuration, the following may be achieved.

That is, according to the hot water supply system of the aforementioned configuration, when the hot water supply load is small, a countermeasure can be taken by operating only the main water heater; when the hot water supply load increases, a countermeasure can be taken by complementarily operating the sub water heater. The configuration is suitable for applications (for example, hot water supply applications in restaurants or hotels) that require a wide range of hot water output from small to large amounts.

On the other hand, when the immediate hot water supply operation is performed, heating of hot water in the hot water circulation path is performed using only the main water heater, and heating of hot water using the sub water heater is avoided. If complementary operation by the sub water heater is performed during the immediate hot water supply operation, it is difficult to determine whether a fluctuation in circulation flow rate is due to the hot water supply terminal being in the opened state. By prohibiting complementary operation, the determination can be made with certainty.

A hot water supply system provided according to a second aspect of the disclosure includes: a water heater, including an internal hot water flow path connected to a water inlet and a hot water outlet, as well as a hot water heating section provided in the internal hot water flow path, and enabling hot water entered from the water inlet to be heated before reaching the hot water outlet; an external hot water flow path, arranged outside the water heater, and enabling hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal; a pump for hot water circulation, configured as a separate device from the water heater, provided in the external hot water flow path, and enabling an immediate hot water supply operation in which hot water is circulated in a predetermined hot water circulation path of the external hot water flow path and the internal hot water flow path when the hot water supply terminal is in a closed state; a control part, capable of executing on/off control of driving of the pump; a flow sensor, for detecting a hot water flow rate in the hot water circulation path during the immediate hot water supply operation; and a temperature sensor in the hot water circulation path, for detecting a hot water temperature on an inlet side of the hot water heating section. The control part is configured to, if a temperature of hot water in the hot water circulation path does not rise to a predetermined first temperature or higher, determine that the hot water supply terminal is in an opened state and stop driving of the pump, despite a fact a cumulative flow rate of hot water in the hot water circulation path from start of the immediate hot water supply operation has reached a predetermined reference capacity set corresponding to a capacity of the hot water circulation path. When the immediate hot water supply operation is performed in a test operation mode of the hot water supply system, a hot water flow rate in the hot water circulation path from a point when delivery of heated hot water from the hot water heating section to the hot water circulation path is started until the heated hot water reaches the temperature sensor and a temperature detected by the temperature sensor rises to a predetermined second temperature or higher is obtained, and the predetermined reference capacity can be determined based on the hot water flow rate.

According to such a configuration, the following may be achieved.

That is, in the case where the immediate hot water supply operation is started with the hot water supply terminal closed and hot water heated by the water heater flows through the hot water circulation path, if the hot water flows to the extent that its cumulative flow rate reaches the predetermined reference capacity, a detected value of hot water temperature detected by the temperature sensor should normally rise to the predetermined first temperature or higher. However, unlike the above, if the detected value of hot water temperature does not rise to the first temperature or higher, it is possible to determine that the hot water supply terminal is in the opened state. According to the aforementioned configuration, when such a determination is made, driving of the pump is stopped. Here, the predetermined reference capacity is determined based on the hot water flow rate in the hot water circulation path obtained by actually driving the pump during the test operation of the hot water supply system. Accordingly, it is possible to set the predetermined reference capacity to an appropriate value. The configuration is preferable in view of solving a problem that the pump remains driven even after the hot water supply terminal is opened.

In the disclosure, it is also possible to combine characteristic configurations of the hot water supply system provided by the first aspect and the second aspect, respectively.

According to such a configuration, when the hot water supply terminal is opened during the immediate hot water supply operation, this situation can be relatively accurately detected and control to stop driving of the pump can be relatively appropriately performed.

Hereinafter, embodiments of the disclosure will be specifically described with reference to the drawings.

A hot water supply system SY illustrated in FIG. 1 includes a water heater A, an external hot water flow path 2, and a pump P for hot water circulation.

The water heater A includes: an internal hot water flow path 1; a heat exchanger 3 for hot water heating, provided in the internal hot water flow path 1; a burner 4, such as a gas burner for heating the heat exchanger 3; a controller 6; temperature sensors Sa to Sc; flow (flow rate per unit time) sensors Sd and Se; flow control valves Va and Vb; and an outer case 5, accommodating the foregoing components.

The heat exchanger 3 corresponds to a specific example of a “hot water heating section” mentioned in the disclosure. The controller 6 corresponds to a specific example of a “control part” mentioned in the disclosure.

The internal hot water flow path 1 has a water inlet 10 and a hot water outlet 11 at both ends. The internal hot water flow path 1 includes: an internal water entry path 12, for guiding hot water supplied to the water inlet 10 to an inlet 3a of the heat exchanger 3 to be heated by the heat exchanger 3; and an internal hot water discharge path 13, for guiding the hot water heated by the heat exchanger 3 from an outlet 3b of the heat exchanger 3 to the hot water outlet 11. The internal water entry path 12 and the internal hot water discharge path 13 are connected by a bypass flow path 14. By mixing unheated hot water flowing through the bypass flow path 14 with heated hot water flowing through the internal hot water discharge path 13, it is possible to adjust the temperature of the heated hot water.

A mixing ratio of the hot water can be controlled to a desired ratio by use of the flow control valves Va and Vb as well as the flow sensors Sd and Se. A final outflow hot water temperature from the hot water outlet 11 of the water heater A can be detected using the temperature sensor Sc. An inflow water temperature to the heat exchanger 3 and an outflow hot water temperature from the heat exchanger 3 can be detected using the temperature sensors Sa and Sb.

The external hot water flow path 2 includes: an external water entry path 20, including a water supply pipe 20a such as a water pipe and enabling hot water supply (water entry) from the outside to the water inlet 10; an external hot water discharge path 21, enabling hot water supply from the hot water outlet 11 to the hot water supply terminal 8; and a connection flow path 22 (portion between intersections N1 and N2 in FIG. 1), connecting the external water entry path 20 and the external hot water discharge path 21. In FIG. 1, the number of hot water supply terminals 8 is one. However, the number may be plural.

The pump P is configured separately from the water heater A. For example, the pump P may be a so-called locally procured item, and is provided in the connection flow path 22 of the external hot water flow path 2. In the hot water supply system SY, an immediate hot water supply operation is possible. In the immediate hot water supply operation, the pump P is driven with the hot water supply terminal 8 closed. At that time, a hot water circulation path C indicated by a bold line in FIG. 2A is formed. The hot water circulation path C is a path in which the hot water that has reached the hot water outlet 11 through the internal hot water discharge path 13 from the heat exchanger 3 passes through the external hot water flow path 2 and flows into the water inlet 10 again, and returns to the heat exchanger 3 through the internal water entry path 12. In the immediate hot water supply operation, the heated hot water is circulated through the path indicated by the bold line in FIG. 2A.

The flow sensor Sd corresponds to an example of a “flow sensor for detecting a hot water flow rate in a hot water circulation path during an immediate hot water supply operation” mentioned in the disclosure. The temperature sensor Sa corresponds to an example of a “temperature sensor for detecting a hot water temperature on an inlet side of a hot water heating section in a hot water circulation path” mentioned in the disclosure.

The controller 6 is configured using a microcomputer or the like, and executes operation control of each part of the water heater A. However, the controller 6 is also capable of controlling on/off switching of driving of the pump P. As described later, the controller 6 is further capable of executing control of the immediate hot water supply operation, control of a test operation accompanied by learning control for performing the immediate hot water supply operation, and so on. In the embodiment illustrated in FIG. 1, the pump P has a relatively low output. Driving power is supplied from the controller 6 to the pump P, and on/off of driving of the pump P is freely switched by on/off of the supply of driving power.

However, a configuration as illustrated in FIG. 3, for example, can be used in place of the above configuration. In FIG. 3, the supply of driving power to the pump P is performed from a power supply 90 such as a general commercial power source. However, the supply of power from the power supply 90 to the pump P is switched on and off using a switch 91, and the switching is executed by the controller 6. Such a configuration is suitably applicable even if the pump P has a high output.

A remote control 60 that is installed in, for example, a bathroom or kitchen, is communicatively connected to the controller 6. The remote control 60 includes: multiple operating switches 60a; a display section 60b, for data displaying; and a speaker (not illustrated), capable of generating various voice messages or warning sounds.

Next, an example of operation control in the hot water supply system SY, as well as effects thereof, will be described with reference to the flowcharts in FIG. 4 and FIG. 5.

In the hot water supply system SY, a normal operation (normal hot water supply operation) and the immediate hot water supply operation are possible, and learning is performed to appropriately execute these operations. This learning is performed during setting of a test operation mode of the hot water supply system SY.

Specifically, when a selection is made to start the immediate hot water supply operation in the test operation mode by operating the operating switch 60a of the remote control 60 or the like, in order to execute the test operation, the pump P is driven on under the control of the controller 6 (S1: YES, S2). However, in an initial stage of the immediate hot water supply operation in the test operation mode, the burner 4 is maintained off, and hot water heating is put into a standby state.

By driving of the pump P, circulation of hot water through the hot water circulation path C illustrated with reference to FIG. 2A is started. Meanwhile, the controller 6 also starts detecting a hot water flow rate using the flow sensor Sd (S3). As a result, if a fluctuation range of the hot water flow rate within a predetermined second time Tb falls within a predetermined range, the controller 6 sets an average value of the detected hot water flow rate as a detected value Qb [L/min] and stores the same (S4: YES, S5).

On the other hand, for example, if air removal in the hot water circulation path C is not sufficient, the fluctuation range of the hot water flow rate increases, and a situation occurs in which the fluctuation range of the hot water flow rate does not fall within the predetermined range. In this case, detection of the hot water flow rate is considered to have an error, and detection of the hot water flow rate is performed all over again (S4: NO, S3). If there is no error after the detection of the hot water flow rate is performed all over again, an average value of the hot water flow rate obtained by performing the detection all over again is set as the detected value Qb [L/min].

After the aforementioned processing is ended, the controller 6 drives the burner 4 on and starts hot water heating (S6). Accordingly, heated hot water is sent from the heat exchanger 3 to the internal hot water discharge path 13. After the burner 4 is driven on, it is determined whether a temperature detected by the temperature sensor Sa has risen to a predetermined second temperature T2 or higher (S7). The second temperature T2 is, for example, a temperature obtained by adding an appropriate value to a temperature detected by the temperature sensor Sa before the burner 4 is driven on.

When the temperature detected by the temperature sensor Sa rises to the second temperature T2 or higher, based on a time required from the start of hot water heating to a point when the temperature rises and a circulation flow rate Qb [L/min] of hot water, the controller 6 calculates and stores a capacity AQb of the hot water circulation path C (S7: YES, S8). The capacity AQb corresponds to the capacity (approximate value) of the hot water circulation path C, and is used in determining a reference capacity AQa described later.

The situation in which the hot water temperature detected using the temperature sensor Sa rises to the second temperature T2 or higher is a situation in which the hot water heated by the heat exchanger 3 reaches where the temperature sensor Sa is arranged, as illustrated by a bold line in FIG. 2B. The amount (capacity AQb) of heated hot water in this situation is close to an actual capacity of the hot water circulation path C, and there is no particular problem even if the amount is taken as the capacity of the hot water circulation path C.

The aforementioned series of steps for calculating the capacity AQb are carried out in a situation (situation in which the result of step S4 is YES) in which driving of the pump P is stable. Since the detected value Qb [L/min] of the hot water flow rate is a valid value, it is possible to make the capacity AQb a relatively accurate value.

After the aforementioned series of operations are completed, both the burner 4 and the pump P are driven off, and the test operation mode or the immediate hot water supply operation in the test operation mode is ended (S9).

Next, a case is described where the immediate hot water supply operation is performed in a normal operation mode (non-test operation mode).

First, when an immediate hot water supply operation start condition is established by performing a predetermined operation on the remote control 60, or by the hot water temperature detected using the temperature sensor Sa being equal to or lower than a predetermined temperature (temperature required for the immediate hot water supply operation), or the like, the immediate hot water supply operation is started (S21: YES, S22, S23). That is, under the control of the controller 6, the pump P and the burner 4 are sequentially driven on, and the hot water heated by the heat exchanger 3 is sent to the hot water circulation path C. From that point, the controller 6 starts detecting the hot water flow rate in the hot water circulation path C and counting a cumulative flow rate AQ using the flow sensor Sd (S24).

During the immediate hot water supply operation, when the hot water supply terminal 8 is opened, the hot water flow rate in the hot water circulation path C increases. With respect to this, in the hot water supply system SY, when the detected value of the hot water flow rate is equal to or greater than a predetermined reference flow rate Qa [L/min], and the duration continues for a predetermined first time or longer, the controller 6 determines that the hot water supply terminal 8 is in the opened state and drives the pump P off (S25: YES, S26). Here, the reference flow rate Qa is determined based on the detected value Qb as the average value of the hot water flow rate obtained earlier, and is, for example, a value obtained by adding an appropriate correction value Δ1 as a margin to the detected value Qb.

In the way, if the reference flow rate Qa is determined based on the detected value Qb, it is possible to make the reference flow rate Qa a valid value suitable for accurately determining whether the hot water supply terminal 8 is in the opened state. The first time is a time to exclude cases where the detected value of the hot water flow rate momentarily exceeds the reference flow rate Qa, and can be, for example, several seconds. Hence, according to the present embodiment, if the hot water supply terminal 8 is in the opened state, based on an accompanying flow rate change of a predetermined amount or more and a temporal length of such change, the opened state is appropriately detected, and the pump P is driven off.

The immediate hot water supply operation is substantially ended by driving the pump P off, and a normal hot water supply operation is performed thereafter (S27). It is appropriately avoided that the pump P remains driven during the normal hot water supply operation.

On the other hand, when the detected value of the hot water flow rate during the immediate hot water supply operation has not reached the reference flow rate Qa, the result of step S25 is NO, and the pump P has not yet been driven off, the following processing is executed.

That is, when a temperature detected by the temperature sensor Sa rises to a predetermined first temperature T1 or higher, since there is no need to heat the hot water any further, at that point, the immediate hot water supply operation is ended as normal (S28: YES, S30).

Unlike the above, if the temperature detected by the temperature sensor Sa has not risen to the first temperature T1 or higher, and the cumulative flow rate AQ of hot water in the hot water circulation path C reaches the predetermined reference capacity AQa, it is determined that the hot water supply terminal 8 is in the opened state, and the pump P is driven off (S28: NO, S29: YES, S26). In the aforementioned situation, since the cumulative flow rate AQ of hot water has reached the predetermined reference capacity AQa, the detected temperature should normally have reached the first temperature T1 or higher. Since this is not the case, it is considered that the hot water supply terminal 8 is in the opened state with a relatively small opening degree.

The reference capacity AQa is determined based on the capacity AQb (hot water flow rate×(time required from the start of hot water heating to the point when the temperature rises)) of the hot water circulation path C. The reference capacity AQa may be, for example, a value obtained by appropriately correcting the capacity AQb. Alternatively, it is possible to use the capacity AQb as the reference capacity AQa without correction. However, the reference capacity AQa is not limited to the above, and may be determined based on (using) the hot water flow rate in the hot water circulation path C.

Hence, it is possible to set the value of the reference capacity AQa to an appropriate value corresponding to the actual capacity of the hot water circulation path C. Accordingly, the processing for determining whether the hot water supply terminal 8 is in the opened state based on the reference capacity AQa can also be appropriate processing with excellent accuracy.

FIG. 6A and FIG. 6B illustrate another embodiment of the disclosure. In FIG. 6A and FIG. 6B, elements identical or similar to those of the above embodiment are denoted by the same reference numerals as in the above embodiment, and repeated descriptions are omitted as appropriate.

A hot water supply system SYa illustrated in FIG. 6A and FIG. 6B includes, as water heaters: a main water heater Aa (A), preferentially operated for a hot water supply load; and multiple sub water heaters Ab (A), complementarily operated when an insufficient amount of heat is supplied by the main water heater Aa alone. The number of main water heater Aa and sub water heaters Ab is not limited. For example, there may be only one sub water heater Ab.

The main water heater Aa and the sub water heaters Ab are connected to each other via an external hot water flow path 2A. The main water heater Aa includes the external water entry path 20 including the water supply pipe 20a, and has multiple hot water supply terminals 8 connected thereto. In FIG. 6A and FIG. 6B, the remote control 60 is omitted.

The main water heater Aa and the sub water heater Ab have basically the same hardware configuration as the water heater A illustrated in FIG. 1 (in FIG. 6A and FIG. 6B, some of the reference numerals assigned in FIG. 1 are omitted). However, the series of operation controls illustrated in FIG. 4 and FIG. 5, such as on/off control of driving of the pump P, are handled by the main water heater Aa and not by the sub water heater Ab. Operation of the sub water heater Ab can be controlled by the main water heater Aa.

The immediate hot water supply operation in the hot water supply system SYa is executed according to an operation processing procedure as illustrated in FIG. 7. In the flowchart in FIG. 7, the same step numbers as in FIG. 5 are assigned to the operation processing (steps) common with FIG. 5, and repeated descriptions thereof are omitted.

In the immediate hot water supply operation in the hot water supply system SYa, with all of multiple hot water supply terminals 8 closed, heated hot water is circulated in the predetermined hot water circulation path C indicated by a bold line in FIG. 6B. The hot water heating is executed only in the main water heater Aa. That is, in step S23′ of FIG. 7, while the burner 4 of the main water heater Aa is driven on, the burner 4 of the sub water heater Ab is not driven on and is in a driven-on prohibited state. During the immediate hot water supply operation, since a large amount of heat is not required for hot water heating, it is possible to appropriately provide the necessary heat quantity by operating only the main water heater Aa.

In the hot water supply system SYa, if driving of the pump P is turned off assuming that the hot water supply terminal 8 is in the opened state during the immediate hot water supply operation, on condition of this, the driven-on prohibited state of the burner 4 of the sub water heater Ab is canceled (S26, S26A). As long as the pump P is being driven, the sub water heater Ab can be prevented from operating. Thus, a state can be appropriately avoided in which the pump P is inappropriately driven during normal hot water supply operation when the sub water heater Ab is operated.

The disclosure is not limited to the content of the above embodiments. The specific configuration of each part of the hot water supply system according to the disclosure may be modified in various ways within the intended scope of the disclosure.

The specific type or size of the pump is not limited. The specific numerical values of each parameter in the disclosure, such as predetermined reference flow rate, first time, second time, reference capacity, first temperature, and second temperature, are not limited. The hot water circulation path during the immediate hot water supply operation can be any path if the heated hot water circulates in a constant path by driving of the pump, and can be a path other than those described in the above embodiments.

The disclosure can also be applied to a storage-type hot water supply system that includes a hot water storage tank. In this case, for example, a liquid-to-liquid heat exchanger can be used as a heat exchanger for hot water heating, and high-temperature hot water discharged from the hot water storage tank can be used as a medium for hot water heating.

Claims

1. A hot water supply system comprising:

a water heater, comprising an internal hot water flow path connected to a water inlet and a hot water outlet, as well as a hot water heating section provided in the internal hot water flow path, and enabling hot water entered from the water inlet to be heated before reaching the hot water outlet;

an external hot water flow path, arranged outside the water heater, and enabling hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal;

a pump for hot water circulation, configured as a separate device from the water heater, provided in the external hot water flow path, and enabling an immediate hot water supply operation in which hot water is circulated in a predetermined hot water circulation path of the external hot water flow path and the internal hot water flow path when the hot water supply terminal is in a closed state;

a control part, capable of executing on/off control of driving of the pump; and

a flow sensor, for detecting a hot water flow rate in the hot water circulation path during the immediate hot water supply operation, wherein

the control part is configured to, in response to that the hot water flow rate in the hot water circulation path is equal to or greater than a predetermined reference flow rate when the pump is driven and the immediate hot water supply operation is being performed, and duration of this state is equal to or longer than a predetermined first time, determine that the hot water supply terminal is in an opened state and stop driving of the pump; and

in a case where the pump is driven during setting of a test operation mode of the hot water supply system, the hot water flow rate in the hot water circulation path at that time is detected, and the reference flow rate is able to be determined based on a detected value of the hot water flow rate.

2. The hot water supply system according to claim 1, wherein

the control part, in response to driving of the pump during setting of the test operation mode being performed for a predetermined second time or longer, executes processing for determining whether a fluctuation range of the detected value of the hot water flow rate detected during a period during which the driving of the pump during setting of the test operation mode is performed for the second time or longer is a normal value within a predetermined range; and

in a case where the detected value is determined to be a normal value, the reference flow rate is determined based on the detected value, and in a case where the detected value is determined not to be a normal value, the reference flow rate is not determined based on the detected value, and the reference flow rate is able to be determined based on the detected value as a normal value obtained by repeating the processing for determining again thereafter.

3. The hot water supply system according to claim 1, wherein

a main water heater and a sub water heater are provided as the water heater, the main water heater being preferentially operated for a hot water supply load, the sub water heater being complementarily operated in response to an insufficient amount of heat being supplied by the main water heater alone; and

when the immediate hot water supply operation is performed, only the main water heater performs heating of hot water circulating through the hot water circulation path, while the sub water heater maintains a state of being prohibited from heating hot water, and complementary operation of the sub water heater is not allowed unless driving of the pump of the main water heater is stopped.

4. The hot water supply system according to claim 1, further comprising:

in the hot water circulation path, a temperature sensor for detecting a hot water temperature on an inlet side of the hot water heating section, wherein

the control part is configured to, in response to a temperature of hot water in the hot water circulation path not rising to a predetermined first temperature or higher, determine that the hot water supply terminal is in the opened state and stop driving of the pump, despite a fact a cumulative flow rate of hot water in the hot water circulation path from start of the immediate hot water supply operation has reached a predetermined reference capacity set corresponding to a capacity of the hot water circulation path.

5. The hot water supply system according to claim 4, wherein

the control part is configured to be able to, when the immediate hot water supply operation is performed in the test operation mode of the hot water supply system, obtain a hot water flow rate in the hot water circulation path from a point when delivery of heated hot water from the hot water heating section to the hot water circulation path is started until the heated hot water reaches the temperature sensor and a temperature detected by the temperature sensor rises to a predetermined second temperature or higher, and determine the predetermined reference capacity based on the hot water flow rate.

6. A hot water supply system comprising:

a water heater, comprising an internal hot water flow path connected to a water inlet and a hot water outlet, as well as a hot water heating section provided in the internal hot water flow path, and enabling hot water entered from the water inlet to be heated before reaching the hot water outlet;

an external hot water flow path, arranged outside the water heater, and enabling hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal;

a pump for hot water circulation, configured as a separate device from the water heater, provided in the external hot water flow path, and enabling an immediate hot water supply operation in which hot water is circulated in a predetermined hot water circulation path of the external hot water flow path and the internal hot water flow path when the hot water supply terminal is in a closed state;

a control part, capable of executing on/off control of driving of the pump;

a flow sensor, for detecting a hot water flow rate in the hot water circulation path during the immediate hot water supply operation; and

a temperature sensor in the hot water circulation path, for detecting a hot water temperature on an inlet side of the hot water heating section, wherein

the control part is configured to, in response to a temperature of hot water in the hot water circulation path not rising to a predetermined first temperature or higher, determine that the hot water supply terminal is in an opened state and stop driving of the pump, despite a fact a cumulative flow rate of hot water in the hot water circulation path from start of the immediate hot water supply operation has reached a predetermined reference capacity set corresponding to a capacity of the hot water circulation path; and

when the immediate hot water supply operation is performed in a test operation mode of the hot water supply system, a hot water flow rate in the hot water circulation path from a point when delivery of heated hot water from the hot water heating section to the hot water circulation path is started until the heated hot water reaches the temperature sensor and a temperature detected by the temperature sensor rises to a predetermined second temperature or higher is obtained, and the predetermined reference capacity is able to be determined based on the hot water flow rate.