Hot water supply system

Abstract

To provide a hot water supply system which can properly control to stop driving of a pump for hot water circulation by accurately sensing that a hot water supply terminal is made an open state during an instantaneous water heating operation.SOLUTION: When hot water flow rate in a hot water circulation path C becomes prescribed reference flow rate Qa or more and the time becomes prescribed first time or more when a pump P is driven and an instantaneous water heating operation is performed, control means 6 of a hot water supply system SY is configured to stop driving of the pump P by determining that a hot water supply terminal 8 is in an open state. When the pump P is driven when setting a trial operation mode of the hot water supply system SY, hot water flow rate in the hot water circulation path C at the time is detected, and reference flow rate Qa can be determined on the basis of the detection value Qb.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hot water supply system capable of immediate hot water supply operation.

[0002] Here, "instant hot water operation" in this specification refers to an operation for circulating and retaining heated hot water at a predetermined temperature or above in a hot water flow path connected to a hot water terminal in a hot water supply system so that hot water at a predetermined temperature or above can instantly flow out from the hot water terminal when the hot water terminal is opened. [Background technology]

[0003] The present applicant has previously proposed the system shown in Figs. 11 and 13 of Patent Document 1 as a specific example of a conventional hot water supply system. This 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, and the pump is provided in an external hot water flow path connected to the outside of the water heater (outside the exterior case of the water heater). When the hot water supply terminal is in a closed state, the pump is driven to send hot water from the external hot water flow path to the water heater's water inlet and circulate it through a specified hot water circulation path, enabling instant hot water operation. During instant hot water operation, the hot water passes through a hot water heating section in the water heater, so the hot water in the hot water circulation path can be heated to a specified temperature or higher. Therefore, when the hot water supply terminal is opened, heated hot water at a specified temperature or higher can be instantly dispensed from the hot water supply terminal. In such a hot water supply system, the pump is not built into the water heater (inside the exterior case of the water heater), so it is possible to use a locally procured product prepared separately from the water heater, for example, as the pump, which provides excellent versatility when constructing the system.

[0004] However, the above-mentioned conventional techniques still have room for improvement, as will be described below.

[0005] In other words, when the hot water supply terminal is opened during the period when the pump is being driven to provide hot water, it is required that this fact be accurately detected and the driving of the pump be stopped. This is because it is undesirable from various viewpoints for the pump to continue to be driven even when the hot water supply terminal is opened and hot water is being supplied to this hot water supply terminal. Therefore, in Patent Document 1, during instant hot water operation, a flow sensor is used to measure the actual hot water flow rate (flow rate per unit time) in the hot water circulation path, and this is stored in an appropriate control means as an actual flow rate value. This actual flow rate value is the value when the hot water supply terminal is in a fully closed state. On the other hand, during instant hot water operation, when the flow rate of hot water in the hot water circulation path becomes equal to or exceeds the actual flow rate value, it is determined that the hot water supply terminal has been opened, and the operation of the pump is stopped.

[0006] However, with this configuration, in order to reliably detect that the hot water supply terminal has been opened during instant hot water operation, it is necessary to repeatedly execute instant hot water operation beforehand and obtain an appropriate value as the actual flow rate value. Therefore, for example, in the early stages of use of the hot water supply system, it is difficult to properly detect that the hot water supply terminal has been opened during instant hot water operation. Furthermore, when the pump is installed outside the water heater, it is more difficult to determine whether a change in the flow rate of hot water in the hot water circulation path during instant hot water operation is due to the open state of the hot water terminal or due to a change in the driving state of the pump, compared to when the pump is built into the water heater. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-1712 [Patent Document 2] Patent Publication No. 2021-85549 [Patent Document 3] Patent No. 5505129 [Patent Document 4] Patent Publication No. 2021-183890 [Patent Document 5] Patent No. 3810187 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention was devised in light of the circumstances described above, and its objective is to provide a hot water supply system that can accurately detect when the hot water supply terminal is opened during instant hot water operation, and can appropriately control the operation of the hot water circulation pump to stop. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides the following technical solutions.

[0010] A hot water supply system provided by a first aspect of the present invention comprises a water heater having an internal hot water flow path connected to a water inlet and a hot water outlet and a hot water heating unit provided in the internal hot water flow path, and capable of heating hot water entering the water inlet before it reaches 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 from the hot water outlet to a hot water supply terminal, a hot water circulation pump configured as a separate device from the water heater and provided in the external hot water flow path, and enabling instant hot water operation to circulate hot water through a specified 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 closed, and a hot water circulation device capable of controlling the on / off operation of the pump. A hot water supply system comprising a control means and a flow sensor for detecting the hot water flow rate in the hot water circulation path during the instant hot water operation, wherein the control means is configured to determine that the hot water terminal is in an open state and stop driving the pump when the hot water flow rate in the hot water circulation path becomes equal to or exceeds a predetermined standard flow rate and the time for which this occurs becomes equal to or exceeds a predetermined first time when the pump is driven to set the hot water supply system in a trial operation mode, and is configured to detect the hot water flow rate in the hot water circulation path at that time and determine the standard flow rate based on this detected value.

[0011] According to this configuration, the following effects can be obtained. That is, when the hot water supply terminal is opened while the pump is being driven for instant hot water operation, the hot water flow rate in the hot water circulation path increases. In contrast, according to the above configuration, when the hot water flow rate increases and becomes equal to or exceeds a predetermined reference flow rate, and the time period for which the hot water supply terminal is opened is exceeded, the operation of the pump is stopped. Here, the reference flow rate is a value determined based on the detection value of the hot water flow rate obtained by actually driving the pump during the test run of the hot water supply system. Therefore, the reference flow rate can be set to an appropriate value corresponding to the actual situation (actual specifications) of the hot water supply system. In addition, the reference flow rate can be obtained early when the test run of the hot water supply system is performed, and can be set to a value that appropriately corresponds to the open state of the hot water supply terminal during instant hot water operation from the early stage when the user actually uses and operates the hot water supply system after the test run. Therefore, this is preferable in terms of eliminating the problem that the pump continues to be driven even though the hot water supply terminal is opened during instant hot water operation.

[0012] In the present invention, preferably, when the pump is driven for a predetermined second time or more when the trial operation mode is set, the control means executes a judgment process to determine whether the fluctuation range of the detection value of the hot and cold water flow rate detected during that period is a normal value within a predetermined range, and if it is determined that it is a normal value, it determines the reference flow rate based on the detection value, whereas if it is determined that it is not a normal value, it is not configured to determine the reference flow rate based on the detection value, and then the judgment process is repeated again to determine the reference flow rate based on the detection value as a normal value obtained.

[0013] According to this configuration, the following effects can be obtained. That is, for example, in the early stages of the trial operation mode, the hot and cold water flow rate may be unstable and fluctuate greatly when the pump is running due to factors such as remaining air in the hot and cold water circulation path. In such cases, the detected value of the hot and cold water flow rate is determined to be an abnormal value, and the reference flow rate is not determined based on this detected value. When the state of each part of the hot water supply system stabilizes and the range of fluctuation in the detected value of the hot and cold water flow rate in the hot and cold water circulation path becomes smaller, the reference flow rate is determined based on the detected value of the hot and cold water flow rate. This makes it even more certain that the reference flow rate is an appropriate value that corresponds to the original specifications of the hot water supply system.

[0014] In the present invention, the water heater preferably comprises a main water heater which is operated with priority in response to the hot water supply load, and a sub-water heater which is operated in supplementary operation when the main water heater alone does not provide enough heat, and when the instant hot water operation is performed, the hot water circulating through the hot water circulation path is heated only by the main water heater, while the sub-water heater maintains a state in which heating of hot water is prohibited, and supplementary operation of the sub-water heater is not permitted unless the operation of the pump of the main water heater is stopped.

[0015] According to this configuration, the following effects can be obtained. In other words, with the hot water supply system of the above configuration, when the hot water supply load is small, only the main water heater can be operated to handle the load, and when the hot water supply load increases, the sub-water heater can be operated in supplementary mode to handle the load, making the system suitable for applications requiring a wide range of hot water output, from small to large amounts (for example, hot water supply applications in restaurants, hotels, etc.). On the other hand, when instant hot water operation is performed, the hot water in the hot water circulation path is heated only by the main hot water heater, and heating of the hot water using the sub-hot water heater is avoided. If a supplementary operation is performed by the sub-hot water heater during instant hot water operation, it becomes difficult to determine whether the fluctuation in the circulation flow rate is due to the hot water terminal being in the open state, but by prohibiting the supplementary operation, the determination can be made more certain.

[0016] A hot water supply system provided by a second aspect of the present invention comprises a water heater having an internal hot water flow path connected to a water inlet and a hot water outlet and a hot water heating unit provided in the internal hot water flow path, and capable of heating hot water entering the water inlet before it reaches 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 hot water circulation pump configured as a separate device from the water heater and provided in the external hot water flow path, and enabling instant hot water operation to circulate hot water through a specified 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 closed, and a drive mechanism for driving the pump. A hot water supply system comprising a control means capable of executing on / off control, a flow rate sensor for detecting the hot water flow rate in the hot water circulation path during the instant hot water operation, and a temperature sensor for detecting the hot water temperature at the inlet side of the hot water heating section in the hot water circulation path, wherein the control means is configured to determine that the hot water supply terminal is in an open state and stop driving the pump when the temperature of the hot water in the hot water circulation path does not rise to or above a predetermined first temperature even though the integrated flow rate of the hot water in the hot water circulation path from the start of the instant hot water operation has reached a predetermined reference capacity set corresponding to the capacity of the hot water circulation path, and When the instant hot water operation is performed in this mode, the hot water flow rate of the hot water circulation path is calculated from the point when the heated hot water heating section starts to send out heated hot water to the hot water circulation path until the heated hot water reaches the temperature sensor and the temperature detected by the temperature sensor rises above a predetermined second temperature, and the specified reference capacity is determined based on this hot water flow rate.

[0017] According to this configuration, the following effects can be obtained. That is, when the hot water supply terminal is closed and the hot water heated by the water heater flows through the hot water circulation path, if the accumulated flow rate reaches the predetermined reference capacity, the hot water temperature detected by the temperature sensor should rise to a predetermined first temperature or higher. However, if the hot water temperature detection value does not rise to the first temperature or higher, it can be determined that the hot water supply terminal has been opened. According to the above configuration, when such a determination is made, the operation of the pump is stopped. Here, the predetermined reference capacity is determined based on the hot water flow rate of the hot water circulation path obtained by actually driving the pump during the test run of the hot water supply system. Therefore, the predetermined reference capacity can be set to an appropriate value, which is preferable in terms of eliminating the problem that the pump continues to be driven even though the hot water supply terminal is opened.

[0018] In the present invention, it is also possible to combine the characteristic configurations of the hot water supply system provided by each of the first and second aspects. With this configuration, when the hot water supply terminal is opened during instant hot water operation, this fact can be detected more accurately, and the pump drive stop control can be performed more appropriately.

[0019] Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic explanatory diagram showing an example of a hot water supply system according to the present invention. [Diagram 2] FIG. 2(a) is a schematic explanatory diagram showing the state of the hot water supply system shown in FIG. 1 during hot water instant operation, and FIG. 2(b) is a schematic explanatory diagram showing the state during a test run. [Diagram 3] FIG. 4 is a schematic explanatory diagram of a main portion of another example of a hot water supply system according to the present invention. [Figure 4]2 is a flowchart showing an example of an operation procedure executed in the hot water supply system shown in FIG. [Diagram 5] 10 is a flowchart showing another example of the operation procedure executed in the hot water supply system shown in FIG. [Figure 6] FIG. 2(a) is a schematic diagram showing another example of a hot water supply system according to the present invention, and FIG. 2(b) is a schematic diagram showing the state of the hot water supply system shown in (a) during instant hot water operation. [Figure 7] 7 is a flowchart showing an example of an operation procedure executed in the hot water supply system shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0022] The hot water supply system SY shown in FIG. 1 includes a water heater A, an external hot water flow path 2, and a pump P for circulating hot water.

[0023] The water heater A includes an internal hot water flow path 1, a heat exchanger 3 for heating hot water provided in the internal hot water flow path 1, a burner 4 such as a gas burner for heating the heat exchanger 3, a control unit 6, temperature sensors Sa to Sc, flow rate (flow rate per unit time) sensors Sd, Se, flow rate control valves Va, Vb, and an outer case 5 for housing these. The heat exchanger 3 corresponds to a specific example of the "hot water heating section" of the present invention. The control section 6 corresponds to a specific example of the "control means" of the present invention.

[0024] The internal hot water flow path 1 has a water inlet 10 and a hot water outlet 11 at both ends, and is equipped with an internal water inlet path 12 for directing hot water supplied to the water inlet 10 to the inlet 3a of the heat exchanger 3 and heating it by the heat exchanger 3, and an internal hot water outlet path 13 for directing the hot water heated by the heat exchanger 3 from the outlet 3b of the heat exchanger 3 to the hot water outlet 11. The internal water inlet path 12 and the internal hot water outlet path 13 are connected by a bypass path 14, and by mixing the heated hot water flowing through the internal hot water outlet path 13 with the unheated hot water flowing through the bypass path 14, it is possible to adjust the temperature of the heated hot water. The mixing ratio of hot and cold water can be controlled to a desired ratio by using flow control valves Va, Vb and flow sensors Sd, Se. The final temperature of hot water exiting the hot water outlet 11 of the water heater A can be detected by using a temperature sensor Sc. The temperature of water entering the heat exchanger 3 and the temperature of hot water exiting the heat exchanger 3 can be detected by using temperature sensors Sa, Sb.

[0025] The external hot water flow path 2 includes an external water inlet path 20 that includes a water supply pipe 20a such as a water pipe, and allows hot water to be supplied (inlet) from the outside to the water inlet 10, an external hot water outlet path 21 that allows hot water to be supplied from the hot water outlet 11 to the hot water supply terminal 8, and a connection path 22 (the portion between intersections N1 and N2 in Fig. 1) that connects the external water inlet path 20 and the external hot water outlet path 21. In Fig. 1, the number of hot water supply terminals 8 is one, but there may be more than one.

[0026] The pump P is configured separately from the water heater A, and may be, for example, a so-called locally procured item, and is provided in the connection flow path 22 of the external hot water flow path 2. In this hot water supply system SY, an instant hot water operation is possible, and in this instant hot water operation, the pump P is driven with the hot water supply terminal 8 in a closed state. At that time, a hot water circulation path C shown by the thick line in FIG. 2(a) is configured. This hot water circulation path C is a path that causes hot water that has reached the hot water outlet 11 from the heat exchanger 3 via the internal hot water outlet path 13 to enter the water inlet 10 again via the external hot water flow path 2, and then returns to the heat exchanger 3 via the internal water inlet path 12. In the instant hot water operation, heated hot water is circulated through the path shown by the thick line in FIG. 2(a). The flow rate sensor Sd corresponds to an example of "a flow rate sensor for detecting the flow rate of hot water in the hot water circulation path during instant hot water operation" in the present invention. The temperature sensor Sa corresponds to an example of "a temperature sensor for detecting the hot water temperature on the inlet side of the hot water heating section in the hot water circulation path" in the present invention.

[0027] The control unit 6 is configured using a microcomputer and the like, and executes operational control of each part of the water heater A. However, it is also possible to control the on / off switching of the drive of the pump P, and as will be described later, it is also possible to control instant hot water operation and control a trial run involving learning control for instant hot water operation. In the embodiment shown in Fig. 1, the pump P has a relatively low output, and drive power is supplied to the pump P from the control unit 6, and the drive of the pump P can be freely switched on and off by turning the power on and off. However, instead of this, for example, a configuration as shown in Fig. 3 may be used. In Fig. 3, driving power is supplied to the pump P from a power source 90 such as a general commercial power source. However, the power supply from the power source 90 to the pump P is switched on and off using a switch 91, and this switching is executed by the control unit 6. Such a configuration can be suitably used even if the pump P is a high-output one.

[0028] A remote control 60 installed in, for example, a bathroom or a kitchen is communicatively connected to the control unit 6. The remote control 60 includes a plurality of operation switches 60a, a display unit 60b for displaying data, and a speaker (not shown) capable of generating various voice messages, warning sounds, and the like.

[0029] Next, an example of operational control in the hot water supply system SY and its operation will be described with reference to the flow charts of FIGS.

[0030] The hot water supply system SY is capable of normal operation (normal hot water supply operation) and instant hot water operation, and learning is performed to properly execute these operations. This learning is performed when the hot water supply system SY is set to the test operation mode.

[0031] Specifically, when the operation switch 60a of the remote control 60 is operated to select the start of instant hot water operation in the test operation mode, the pump P is turned on by the control of the control unit 6 to execute the test operation (S1: YES, S2). However, in the initial stage of the instant hot water operation in the test operation mode, the burner 4 is maintained in the off state, and hot water heating is in the standby state.

[0032] Driving the pump P described above starts the circulation of hot and cold water in the hot and cold water circulation path C shown in FIG. 2(a). At the same time, the control unit 6 also starts detecting the hot and cold water flow rate using the flow rate sensor Sd (S3). As a result, if the fluctuation range of the hot and cold water flow rate within a predetermined second time Tb falls within a predetermined range, the control unit 6 stores the average value of this detected hot and cold water flow rate as the detection value Qb [L / min] (S4: YES, S5).

[0033] On the other hand, for example, if air is not sufficiently removed from the hot and cold water circulation path C, the fluctuation range of the hot and cold water flow rate will become large, and a situation will occur in which the fluctuation range of the hot and cold water flow rate does not fall within the above-mentioned specified range. In this case, it is determined that there is an error in the detection of the hot and cold water flow rate, and the hot and cold water flow rate detection will be redone (S4: NO, S3). If this redo results in an error-free detection of the hot and cold water flow rate, the average value of the hot and cold water flow rates obtained by this redo will be set as the detection value Qb [L / min].

[0034] After the above-mentioned processing is completed, the control unit 6 turns on the burner 4 to start heating the hot water (S6). This causes the heat exchanger 3 to send heated hot water to the internal hot water outlet passage 13. After the burner 4 is turned on, it is determined whether the 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 the temperature detected by the temperature sensor Sa before the burner 4 was turned on.

[0035] When the temperature detected by the temperature sensor Sa rises to or above the second temperature T2, the control unit 6 calculates and stores the capacity AQb of the hot water circulation path C based on the time required from when the hot water heating starts to when the temperature rises and the hot water circulation flow rate Qb [L / min] (S7: YES, S8). This capacity AQb corresponds to the capacity (approximate value) of the hot water circulation path C and is used to determine the reference capacity AQa described later. The situation in which the hot water temperature detected by the temperature sensor Sa rises to or exceeds the second temperature T2 is when the hot water heated by the heat exchanger 3 reaches the location where the temperature sensor Sa is located, as shown by the bold line in Fig. 2(b). The amount of heated hot water (capacity AQb) in this situation is close to the actual capacity of the hot water circulation path C, and there is no problem in assuming this as the capacity of the hot water circulation path C. The series of steps for calculating the capacity AQb described above is performed when the operation of pump P is stable (step S4 is YES), and since the detected hot and cold water flow rate Qb [L / min] is a reasonable value, the capacity AQb can be made a more accurate value. When the series of operations described above is completed, the burner 4 and the pump P are both turned off, and the test operation mode or the instant hot water operation in the test operation mode ends (S9).

[0036] Next, a case where the instant hot water operation is performed in the normal operation mode (non-test run mode) will be described.

[0037] First, when a predetermined operation is performed on the remote control 60, or when the hot and cold water temperature detected using the temperature sensor Sa falls below a predetermined temperature (the temperature at which instant hot water operation is required), and the conditions for starting the instant hot water operation are met, the instant hot water operation starts (S21: YES, S22, S23). That is, under the control of the control unit 6, the pump P and burner 4 are sequentially driven on, and the hot and cold water heated by the heat exchanger 3 is sent out to the hot and cold water circulation path C. Also, from that point on, the control unit 6 starts using the flow sensor Sd to detect the flow rate of the hot and cold water in the hot and cold water circulation path C, and to count the accumulated flow rate AQ (S24).

[0038] During instant hot water operation, when the hot water terminal 8 is opened, the hot water flow rate in the hot water circulation path C increases. In contrast, in this hot water supply system SY, when the detected hot water flow rate value becomes equal to or exceeds a predetermined reference flow rate Qa [L / min] and this time period continues for a predetermined first time period or longer, the control unit 6 determines that the hot water terminal 8 has been opened, and turns off the drive of the pump P (S25: YES, S26). Here, the reference flow rate Qa is determined based on the detection value Qb, which is the average value of the hot water flow rate previously determined, and is, for example, a value obtained by adding an appropriate correction value Δ1 as a margin to the detection value Qb.

[0039] In this way, if the reference flow rate Qa is determined based on the detection value Qb, it is possible to set this reference flow rate Qa to an appropriate value suitable for accurately judging whether or not the hot water supply terminal 8 is in the open state. The first time period is a time period for eliminating cases in which the hot water flow rate detection value merely momentarily exceeds the reference flow rate Qa, and can be set to, for example, about several seconds. For this reason, according to this embodiment, when the hot water supply terminal 8 is in the open state, the fact that the hot water supply terminal 8 is in the open state is appropriately detected based on the associated change in flow rate of a predetermined amount or more and the duration of such change, and the operation of the pump P is turned off. By turning off the pump P, the instant hot water supply operation is essentially terminated, and normal hot water supply operation is performed thereafter (S27). During this normal hot water supply operation, the pump P is appropriately prevented from remaining driven.

[0040] On the other hand, when the detected flow rate of hot and cold water during instant hot water operation has not reached the reference flow rate Qa, step S25 is NO, and the pump P has not yet been turned off, the following process is executed. In other words, when the temperature detected by the temperature sensor Sa rises above a predetermined first temperature T1, there is no need to heat the water any further, so at that point the instant hot water operation ends as normal (S28: YES, S30).

[0041] Unlike the above, when the temperature detected by the temperature sensor Sa has not risen above the first temperature T1 and the accumulated flow rate AQ of hot and cold water in the hot and cold water circulation path C reaches a predetermined reference capacity AQa, the hot water terminal 8 is determined to be in the open state and the pump P is turned off (S28: NO, S29: YES, S26). In the above situation, the accumulated flow rate AQ of hot and cold water has reached the predetermined reference capacity AQa, so the detected temperature should normally be above the first temperature T1, but this is not the case, so it is considered that the hot water terminal 8 is in the open state with a relatively small opening. The reference capacity AQa is determined based on the capacity AQb of the hot water circulation path C (hot water flow rate x (time required from when hot water heating starts until the temperature rises)), and for example, the capacity AQb may be appropriately corrected, or the capacity AQb may be left as the reference capacity AQa without being corrected. However, the reference capacity AQa is not limited to this and may be determined based on the hot water flow rate in the hot water circulation path C (using the hot water flow rate). For this reason, the value of the reference capacity AQa was set to correspond to the actual capacity of the hot water circulation path C. It is possible to set this to an appropriate value. Therefore, the process of determining whether or not hot water supply terminal 8 is in the open state based on this reference capacity AQa can also be an appropriate process with excellent accuracy.

[0042] Fig. 6 shows another embodiment of the present invention. In this figure, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as those in the above embodiment, and duplicated explanations will be omitted as appropriate.

[0043] The hot water supply system SYA shown in Fig. 6 includes a main hot water supply Aa (A) that is operated preferentially in response to the hot water supply load, and a number of sub-hot water supply units Ab (A) that are operated as a supplement when the main hot water supply unit Aa alone does not provide enough heat. The number of these units is not limited, and for example, the number of sub-hot water supply units Ab can be one. The main water heater Aa and the sub water heater Ab are connected to each other via an external hot and cold water flow path 2A, which includes an external water inlet 20 including a water supply pipe 20a, and is connected to a plurality of hot water terminals 8. In FIG. 6, the remote control 60 is omitted.

[0044] The basic hardware configuration of the main water heater Aa and the sub water heater Ab is the same as that of the water heater A shown in Figure 1 (some of the symbols used in Figure 1 have been omitted in Figure 6). However, the series of operational controls shown in Figures 4 and 5, such as on / off control of the drive of pump P, are handled by the main water heater Aa and not by the sub water heater Ab. In addition, the operation of the sub water heater Ab can be controlled by the main water heater Aa.

[0045] The instant hot water operation in the hot water supply system SYa is executed according to the operational processing procedure shown in Fig. 7. In the flowchart of this figure, the operational processing (steps) common to Fig. 5 are given the same step numbers as in Fig. 5, and the repeated explanation is omitted. In the instant hot water operation of the hot water supply system SYA, heated hot water is circulated in a predetermined hot water circulation path C shown by a bold line in Fig. 6(b) with all of the multiple hot water supply terminals 8 in a closed state, but this hot water heating is performed only in the main hot water heater Aa. That is, in step S23' in Fig. 7, the burner 4 of the main hot water heater Aa is turned on, but the burner 4 of the sub hot water heater Ab is not turned on and is in a prohibited state. During instant hot water operation, a large amount of heat is not required for hot water heating, so the required amount of heat can be adequately provided by operating only the main hot water heater Aa.

[0046] Furthermore, in this hot water supply system SYA, if the hot water supply terminal 8 is in an open state during instant hot water operation and the drive of the pump P is turned off, the prohibition on turning on the burner 4 of the sub-hot water heater Ab is lifted under this condition (S26, S26A). Since the sub-hot water heater Ab can be prevented from operating as long as the pump P is being driven, it is possible to appropriately avoid a state in which the pump P is being driven inappropriately during normal hot water supply operation when the sub-hot water heater Ab is operating.

[0047] The present invention is not limited to the above-described embodiment, and the specific configuration of each part of the hot water supply system according to the present invention can be freely designed and modified in various ways within the intended scope of the present invention.

[0048] The specific type and size of the pump are not limited. In addition, the specific values ​​of each parameter, such as the predetermined reference flow rate, the first time, the second time, the reference capacity, the first temperature, and the second temperature, in the present invention are not limited. The hot water circulation path during the instant hot water operation may be a path other than that of the above-mentioned embodiment as long as the heated hot water is circulated through a fixed path by driving the pump. The present invention can also be applied to a hot water supply system of a storage type equipped with a hot water storage tank. In this case, for example, a liquid-liquid heat exchanger is used as a heat exchanger for heating hot water, and the hot water storage tank is The high-temperature hot water coming out of the tank can be used as a medium for heating the hot water. [Explanation of symbols]

[0049] SY,SYa Hot water system A Water heater C Hot water circulation route P-Pump Sa Temperature Sensor Sd flow sensor 1 Internal water flow path 10 Water Inlet 11 Tap hole 2 External hot water flow path 3 Heat exchanger (hot water heating section) 6 Control section (control means) 8 Hot water terminal

Claims

1. A water heater having an internal hot water flow path connected to a water inlet and a hot water outlet, and a hot water heating unit provided in the internal hot water flow path, and capable of heating hot water entering the water inlet before it reaches the hot water outlet; An external hot water flow path that is arranged outside the water heater and enables hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal; A hot water circulation pump that is configured as a separate device from the water heater, is provided in the external hot water flow path, and enables an instant hot water operation in which hot water is circulated through 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 means capable of controlling the on / off of the drive of the pump; A flow rate sensor for detecting a flow rate of hot water in the hot water circulation path during the instant hot water operation; A hot water supply system comprising: The control means is configured to determine that the hot water supply terminal is in an open state and stop driving the pump when the hot water flow rate in the hot water circulation path becomes equal to or greater than a predetermined reference flow rate and the time period during which the hot water flow rate becomes equal to or greater than a predetermined first time period while the pump is being driven to perform the instant hot water operation; This hot water supply system is characterized in that when the pump is driven during the trial 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 determined based on this detected value.

2. The hot water supply system according to claim 1, When the pump is driven for a predetermined second time or more in the test operation mode, the control means executes a process of determining whether or not the fluctuation range of the detected value of the hot and cold water flow rate detected during that period is a normal value within a predetermined range; This hot water supply system is configured such that if it is determined that the detected value is normal, the reference flow rate is determined based on the detected value, whereas if it is determined that the detected value is not normal, the reference flow rate is not determined based on the detected value, and the reference flow rate is determined based on the detected value as a normal value obtained by repeating the judgment process again.

3. The hot water supply system according to claim 1, The water heater includes a main water heater that is operated preferentially in response to a hot water supply load, and a sub water heater that is operated as a supplement when the main water heater alone does not provide enough heat, When the instant hot water operation is performed, the hot water circulating through the hot water circulation path is heated only by the main water heater, while the sub-water heater maintains a state in which heating of hot water is prohibited, and supplementary operation of the sub-water heater is not permitted unless the operation of the pump of the main water heater is stopped.This is a hot water supply system.

4. The hot water supply system according to claim 1, The hot water circulation path further includes a temperature sensor for detecting the hot water temperature on the inlet side of the hot water heating section, The control means of the hot water system is configured to determine that the hot water terminal is in an open state and stop driving the pump when the accumulated flow rate of hot water in the hot water circulation path from the start of the instant hot water operation reaches a predetermined standard capacity set corresponding to the capacity of the hot water circulation path, but the temperature of the hot water in the hot water circulation path does not rise above a predetermined first temperature.

5. The hot water supply system according to claim 4, When the instant hot water operation is performed in the test operation mode of the hot water supply system, the control means The hot water supply system is configured to calculate the hot water flow rate in the hot water circulation path from when the heated hot water reaches the temperature sensor until the temperature detected by the temperature sensor rises above a predetermined second temperature, and to determine the predetermined standard capacity based on this hot water flow rate.

6. A water heater having an internal hot water flow path connected to a water inlet and a hot water outlet, and a hot water heating unit provided in the internal hot water flow path, and capable of heating hot water entering the water inlet before it reaches the hot water outlet; An external hot water flow path that is arranged outside the water heater and enables hot water supply to the water inlet and hot water supply from the hot water outlet to a hot water supply terminal; A hot water circulation pump that is configured as a separate device from the water heater, is provided in the external hot water flow path, and enables an instant hot water operation in which hot water is circulated through 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 means capable of controlling the on / off of the drive of the pump; A flow rate sensor for detecting a flow rate of hot water in the hot water circulation path during the instant hot water operation; A temperature sensor for detecting the temperature of the hot water at the inlet side of the hot water heating section in the hot water circulation path; A hot water supply system comprising: The control means is configured to determine that the hot water supply terminal is in an open state and stop driving the pump when the temperature of the hot water in the hot water circulation path does not rise to a predetermined first temperature or higher even though the cumulative flow rate of the hot water in the hot water circulation path from the start of the instant hot water operation has reached a predetermined reference capacity set corresponding to the capacity of the hot water circulation path, and This hot water supply system is characterized in that when the instant hot water operation is performed in the trial operation mode, the hot water flow rate of the hot water circulation path is calculated from the point when the hot water heating section starts to send heated hot water to the hot water circulation path until the heated hot water reaches the temperature sensor and the temperature detected by the temperature sensor rises above a predetermined second temperature, and the predetermined standard capacity is determined based on this hot water flow rate.

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