Hot water supply system

Abstract

This hot water supply system provides a solution that can effectively suppress instability in hot water temperature caused by running out of hot water in the storage tank. [Solution] The hot water supply system SY includes a hot water depletion determination means 4a that can determine when the hot water storage tank 1 is about to run out of hot water, and a hot water flow control means 4b that, when a predetermined second valve Vb is closed and the first valve Va is open, and hot water is being supplied from the hot water storage tank 1 to the hot water supply channel 31, when the hot water is about to run out, performs a specific valve switching operation to open the second valve Vb while keeping the first valve Va open, thereby ensuring that hot water is supplied from both the hot water storage tank 1 and the auxiliary heat source device A to the hot water supply channel 31 for a predetermined period of time or longer, and then closes the first valve Va.

Description

Technical Field

[0001] The present invention relates to a hot water supply system of a type combining a hot water storage tank and an auxiliary heat source device.

Background Art

[0002] As a specific example of a hot water supply system, there is a combination of a hot water storage tank that stores hot water heated by a main heat source device and an auxiliary heat source device. The auxiliary heat source device is, for example, an instantaneous gas water heater, and can heat the hot water that has entered through a water inlet flow path that does not pass through the hot water storage tank. When the hot water storage tank is about to run out of hot water during the hot water discharge from the hot water storage tank, hot water is discharged from the auxiliary heat source device instead of the hot water storage tank. A hot water discharge flow path provided with a hot water supply terminal is connected to the hot water storage tank, and an auxiliary heat source device is branched and connected to this hot water discharge flow path via a connection flow path. According to the above-described configuration, it is possible to prevent the supply to the hot water supply terminal from being interrupted due to the exhaustion of hot water in the hot water storage tank.

[0003] However, in the above prior art, there was room for improvement as described below.

[0004] That is, in the above prior art, when the hot water storage tank is about to run out of hot water during the hot water discharge from the hot water storage tank, the valve for switching the on / off of the hot water discharge from the auxiliary heat source device to the hot water discharge flow path is switched to the open state, and at the same time, the valve for switching the on / off of the hot water discharge from the hot water storage tank to the hot water discharge flow path is switched to the closed state. In this case, immediately after such valve switching, the unheated hot water existing in the connection flow path connecting the auxiliary heat source device and the hot water discharge flow path flows into the hot water discharge flow path, and this hot water flows downstream of the hot water discharge flow path without being mixed with the hot water from the hot water storage tank. As a result, the range of temperature change of the hot water supplied to the hot water supply terminal becomes large, and there is room for improvement in stabilizing the hot water supply temperature.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Patent No. 5518006 [Patent Document 2] Patent No. 7431449 [Overview of the project] [Problems that the invention aims to solve]

[0006] This invention was conceived under the circumstances described above, and its objective is to provide a hot water supply system that can appropriately suppress instability in the hot water supply temperature caused by running out of hot water in the storage tank. [Means for solving the problem]

[0007] To solve the above problems, the present invention employs the following technical measures.

[0008] The hot water supply system provided by the present invention includes a hot water storage tank that stores hot water heated by a main heat source device and is capable of discharging hot water to a hot water outlet channel equipped with a hot water supply terminal; an auxiliary heat source device capable of heating hot water from an inlet channel that does not pass through the hot water storage tank; a connecting channel that branches and connects the auxiliary heat source device to the hot water outlet channel so that hot water can be discharged from the auxiliary heat source device to the hot water outlet channel; a first valve capable of switching the on and off of hot water discharge from the hot water storage tank to the hot water outlet channel; a second valve capable of switching the on and off of hot water discharge from the auxiliary heat source device to the hot water outlet channel; and a hot water depletion detection device capable of determining when the hot water storage tank is about to run out of hot water. The device is characterized by comprising: a stage, and a hot water flow control means that, when the second valve is closed and the first valve is open, and hot water is being supplied from the hot water storage tank to the hot water supply channel, when the hot water is about to run out, performs a specific valve switching operation to open the second valve while keeping the first valve open, thereby ensuring that hot water is supplied to the hot water supply channel from both the hot water storage tank and the auxiliary heat source device for a predetermined period of time or longer, and then closes the first valve.

[0009] This configuration yields the following effects: In other words, when the hot water storage tank is nearly empty while hot water is being dispensed from it, a specific valve switching operation is performed in which both the first and second valves are opened. As a result, in the hot water dispensing path, the hot water from the connecting path mixes with the hot water dispensed from the storage tank. Therefore, even if the hot water in the connecting path is relatively cold, it does not flow downstream as is, but is heated by mixing with the hot water from the storage tank before flowing downstream. This phenomenon can be continued for a predetermined time or longer. As a result, it is possible to suppress large temperature fluctuations in the hot water supplied to the hot water terminal and stabilize the hot water temperature more than in the conventional technology.

[0010] In the present invention, preferably, the predetermined time is equal to or greater than the time required from the time the specific valve switching operation is performed until the entire volume of hot water in the connecting channel flows into the hot water outlet channel.

[0011] With this configuration, when the hot water storage tank is nearly empty and a specific valve switching operation is performed, the first valve is not closed until the entire volume of hot water in the connecting channel flows into the hot water outlet channel, and hot water continues to flow from the storage tank to the hot water outlet channel. Therefore, this configuration is preferable in suppressing instability in the hot water supply temperature caused by the hot water in the connecting channel flowing into the hot water outlet channel.

[0012] In the present invention, preferably, the auxiliary heat source device is configured to perform hot water heating on the condition that the water inflow rate to the auxiliary heat source device is equal to or greater than a predetermined minimum operating flow rate, and the predetermined time is equal to or greater than the time required from the time after the specific valve switching operation is performed until the water inflow rate to the auxiliary heat source device reaches or greater than the minimum operating flow rate.

[0013] With this configuration, when the hot water storage tank is nearly depleted and a specific valve switching operation is performed, the first valve will not be closed until the water inflow rate to the auxiliary heat source device reaches or exceeds the minimum operating flow rate and the auxiliary heat source device begins heating the hot water. Hot water will continue to flow from the hot water storage tank to the hot water outlet channel. After the first valve is closed, it is properly prevented that unheated water will flow from the connecting channel into the hot water outlet channel.

[0014] In the present invention, preferably, an instant hot water channel is provided which connects the hot water outlet channel and the water inlet channel, and which is equipped with an instant hot water circulation pump that sends the hot water from the hot water outlet channel to the water inlet channel. The auxiliary heat source device is configured to be able to perform hot water heating on the condition that the water inlet flow rate to the auxiliary heat source device is equal to or greater than a predetermined minimum operating flow rate, and the instant hot water circulation pump is configured to be driven after the specific valve switching operation is performed.

[0015] This configuration yields the following effects: In other words, when a specific valve switching operation is performed and the second valve is opened, hot water flows from the connecting channel to the hot water outlet channel, but the flow rate of the hot water is small, and the water inflow to the auxiliary heat source device may not reach the minimum operating flow rate. For example, this can happen when the flow resistance of the auxiliary heat source device is large. In contrast, with the above configuration, the amount of water inflow to the auxiliary heat source device is increased by driving the instant hot water circulation pump, and it can be set to a flow rate above the minimum operating flow rate. Therefore, the hot water can be heated appropriately by the auxiliary heat source device.

[0016] In the present invention, preferably, the instant hot water circulation pump is configured to start driving when the water flow rate into the auxiliary heat source device is less than the minimum operating flow rate after the specific valve switching operation has been performed.

[0017] According to such a configuration, after a specific valve switching operation is executed, when the water inflow rate to the auxiliary heat source device is less than the minimum operating flow rate, the instant hot water circulation pump is driven. Therefore, it is possible to eliminate the waste of driving the instant hot water circulation pump even when it is not necessary to drive the instant hot water circulation pump.

[0018] In the present invention, preferably, after the driving of the instant hot water circulation pump is started corresponding to the execution of the specific valve switching operation, when it is determined whether the water inflow rate to the auxiliary heat source device becomes less than the minimum operating flow rate when the instant hot water circulation pump is temporarily stopped, and when it is determined that the water inflow rate does not reach the minimum operating flow rate, the driving of the instant hot water circulation pump is configured to stop.

[0019] According to such a configuration, when the instant hot water circulation pump is driven after a specific valve switching operation is executed, it is possible to prevent a problem that the heating of hot water by the auxiliary heat source device becomes difficult due to the stop of the driving of the instant hot water circulation pump.

[0020] Other features and advantages of the present invention will become more apparent from the following description of the embodiments of the invention with reference to the accompanying drawings.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic explanatory diagram showing an example of a hot water supply system according to the present invention. [Figure 2] It is a flowchart showing an example of an operation procedure executed in the hot water supply system shown in FIG. 1. [Figure 3] It is a schematic explanatory diagram showing another example of a hot water supply system according to the present invention. [Figure 4] It is a flowchart showing an example of an operation procedure executed in the hot water supply system shown in FIG. 3. [Figure 5] It is a schematic explanatory diagram of a main part showing another example of a hot water supply system according to the present invention.

Embodiments for Carrying Out the Invention

[0022] Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0023] The hot water supply system SY shown in Figure 1 comprises a hot water storage tank 1, a heat pump 2, an auxiliary heat source device A, a control unit 4 including a hot water depletion detection unit 4a and a hot water flow control unit 4b, an inlet water channel 30, an outlet water channel 31, a connecting channel 32, and first and second on / off valves Va and Vb. The heat pump 2 corresponds to a specific example of the "main heat source device" as defined in this invention, and the first and second on-off valves Va and Vb correspond to specific examples of the "first and second valves." The hot water depletion detection unit 4a and the hot water / water flow control unit 4b correspond to specific examples of the "hot water depletion detection means" and the "hot water / water flow control means," respectively.

[0024] The heat pump 2 is a heat source device for heating the hot water stored in the hot water storage tank 1. In this embodiment, the heat pump 2 is a conventionally known vapor compression type (gas liquefaction type) using a refrigerant such as CO2. The lower and upper parts of the hot water storage tank 1 are connected to the heat pump 2 via piping sections 20 and 21 equipped with a pump P3. When the pump P3 is driven, hot water is sent from the lower part of the hot water storage tank 1 to the heat pump 2 via piping section 20 and heated, and this heated hot water flows into the upper part of the hot water storage tank 1 via piping section 21.

[0025] Within the hot water storage tank 1, a temperature layer of hot water is formed, with the upper side being the higher temperature side and the lower side being the lower temperature side. Multiple hot water temperature sensors Sa are installed on the side wall of the hot water storage tank 1, spaced apart in the vertical direction, to detect the temperature of the hot water inside the tank 1. By detecting the temperature using these hot water temperature sensors Sa, it is possible to determine the temperature distribution of the hot water inside the hot water storage tank 1 and the amount of heat stored.

[0026] The water inlet channel 30 is a channel that can guide unheated hot water supplied to the water inlet 39 via a water pipe or the like to the water inlet 38a of the auxiliary heat source device A. However, a branch channel 33 is connected to the water inlet channel 30 at an intermediate point, and it is also possible to supply hot water to the lower part of the hot water storage tank 1 via this branch channel 33.

[0027] The hot water outlet channel 31 is a channel whose starting point is connected to the top of the hot water storage tank 1 and to which a hot water supply terminal 9 is provided at the end. The first on-off valve Va is an electromagnetic on-off valve remotely controlled by the control unit 4 (hot water flow control unit 4b) (the same applies to the second on-off valve Vb), and is installed in the middle of the hot water outlet channel 31, and can switch the on / off of hot water supply from the hot water storage tank 1 to the hot water outlet channel 31. This first on-off valve Va is normally open so that hot water is supplied from the hot water storage tank 1 when the hot water supply terminal 9 is opened.

[0028] The auxiliary heat source device A is configured by combining multiple instantaneous gas water heaters 5. The hot water supply system SY of this embodiment is installed in large-scale accommodation facilities such as hotels and inns, and is a system that can meet large hot water demands, so multiple gas water heaters 5 are used. Of the multiple gas water heaters 5, one gas water heater 5(5a) is the main gas water heater that is operated preferentially in response to the hot water load, and the other gas water heaters 5(5b) are sub-gas water heaters that are operated to supplement the heat when the main gas water heater 5a alone does not provide enough heat.

[0029] Auxiliary heat source device A includes a common water inlet channel 37a and a common hot water outlet channel 37b connected to the water inlet 38a and the hot water outlet 38b, respectively. Each gas water heater 5 has a configuration similar to conventionally known gas water heaters, in which hot water flows from the common inlet 37a into the internal inlet 52 and is heated by passing through a heat exchanger 51 which is heated by a burner 50. The hot water heated by the heat exchanger 51 flows through the internal outlet 53 into the common outlet 37b and reaches the outlet 38b. The gas water heater 5 is equipped with a flow sensor Sb for determining whether the flow rate of hot and cold water passing through the heat exchanger 51 is equal to or greater than a predetermined minimum operating flow rate Qth (MOQ-ON). When the flow rate of hot and cold water is equal to or greater than the minimum operating flow rate Qth, the burner 50 enters a driven combustion state.

[0030] The connecting channel 32 is a channel that branches off and connects the auxiliary heat source device A to an intermediate position Pa downstream of the first on-off valve Va in the hot water outlet channel 31. Hot water heated by the auxiliary heat source device A can flow from the hot water outlet 38b through the connecting channel 32 into the hot water outlet channel 31. The second on-off valve Vb is provided in the water inlet channel 30 and can switch the water inlet to the auxiliary heat source device A on and off (however, it can also be configured to be provided in the connecting channel 32). The second on-off valve Vb can also switch the hot water outlet from the auxiliary heat source device A to the hot water outlet channel 31 on and off, and as described above, corresponds to a specific example of the second valve of the present invention.

[0031] The control unit 4 is configured, for example, using a microcomputer, and performs operational control and data processing for each part of the hot water supply system SY. Although not shown in the diagram, the control unit 4 is also connected via communication to a remote control that has an operation unit used for inputting and setting various data such as the target hot water temperature, and a display unit capable of displaying various data. Functionally, the control unit 4 includes a hot water depletion determination unit 4a and a hot water flow control unit 4b. ru. The hot water depletion detection unit 4a can determine whether the hot water storage tank 1 is nearing a predetermined state of running out of hot water. This determination is made based on the temperature detection signal output from the hot water temperature sensor Sa, by determining the temperature distribution of the hot water in the hot water storage tank 1 and the amount of heat stored, as well as referring to the predicted amount of hot water heat demand in the future, to determine whether the current time is nearing a predetermined state of running out of hot water, that is, whether a state of running out of hot water where the amount of hot water heat in the hot water storage tank 1 is insufficient will occur soon (within a predetermined time from the present). For example, if the temperature of the hot water dispensed from the hot water storage tank 1 is not higher than a predetermined temperature relative to the target hot water supply temperature, it is determined that the tank is nearing a running out of hot water.

[0032] The hot water distribution control unit 4b controls the opening and closing of the first and second on-off valves Va and Vb. When the hot water storage tank 1 is nearing the end of its supply of hot water, it performs a specific valve switching operation to prevent interruption of the hot water supply operation to the hot water terminal 9. The specific details of this operation will be described later.

[0033] Next, an example of the operation control procedure for the hot water supply system SY described above will be explained with reference to the flowchart in Figure 2, and its function will also be described.

[0034] First, when the first on-off valve Va is open and the second on-off valve Vb is closed, and hot water is being supplied from the hot water storage tank 1 to the hot water outlet channel 31 and the hot water supply terminal 9, the hot water depletion determination unit 4a monitors whether the system is nearing a predetermined state of being close to running out of hot water (S1:YES,S2). If this monitoring determines that the system is nearing a running out of hot water, a specific valve switching operation is performed by the hot water flow control unit 4b, which keeps the first on-off valve Va open and opens the second on-off valve Vb (S3:YES,S4). As a result, the unheated hot water that was in the connecting channel 32 flows into the hot water outlet channel 31, and this unheated hot water is mixed with the hot water (hot water) being supplied from the hot water storage tank 1. Therefore, even if the hot water originally present in the connecting channel 32 is at a relatively low temperature, this hot water will not flow directly downstream of the connecting channel 32. Instead, it will be mixed with the hot water from the hot water storage tank 1 and heated before flowing downstream. As a result, the hot water temperature supplied to the hot water supply terminal 9 will not temporarily drop significantly, and the hot water temperature will be stabilized.

[0035] When a predetermined time Ta has elapsed since the start of the aforementioned specific valve switching operation, the first on-off valve Va is closed and the second on-off valve Vb remains open (S5:YES, S6). As a result, the hot water supply from the hot water storage tank 1 stops, and the hot water from the auxiliary heat source device A is properly supplied to the hot water supply channel 31 and the hot water supply terminal 9.

[0036] The predetermined time Ta is preferably set to be longer than the time required from the execution of the specific valve switching operation in step S4 until the entire volume of hot water in the connecting channel 32 flows into the hot water outlet channel 31. With this configuration, the hot water supply from the hot water storage tank 1 to the hot water outlet channel 31 is not interrupted before the entire volume of hot water present in the connecting channel 32 has finished flowing into the hot water outlet channel 31. This more effectively prevents the hot water present in the connecting channel 32 from flowing downstream to the hot water outlet channel 31.

[0037] Furthermore, the predetermined time Ta is set to be longer than the time required from the execution of the specific valve switching operation until the water inflow rate to the auxiliary heat source device A reaches the minimum operating flow rate Qth or higher. Immediately after the execution of the specific valve switching operation, the water inflow rate to the auxiliary heat source device A is low and does not reach the minimum operating flow rate Qth, so it is possible that the burner 50 will remain in a non-operating state for a while. In contrast, with the above configuration, hot water will continue to be dispensed from the hot water storage tank 1 until the water inflow rate to the auxiliary heat source device A reaches the minimum operating flow rate Qth or higher and the hot water heated by the auxiliary heat source device A begins to flow into the hot water outlet channel 31. Also, after the hot water dispensed from the hot water storage tank 1 is interrupted, unheated hot water will flow from the connecting channel 32 into the hot water outlet channel 31. Consequently, the stabilization of the hot water temperature can be further promoted.

[0038] The predetermined time Ta can be changed as appropriate depending on the length of the connecting channel 32. When the hot water supply system SY has predetermined standard specifications and the length (and pipe diameter) of the connecting channel 32 is within a certain range, it is possible to determine in advance the optimal or near-optimal predetermined time Ta through experiments or simulations and use that. Furthermore, the predetermined time Ta can be configured to be increased or decreased as appropriate by the user or maintenance company by operating a switch.

[0039] Whether or not a predetermined time Ta has been reached can be determined by a time measurement method using a timer, but is not limited to this. For example, if the predetermined time Ta is set to be longer than the time required from the execution of a specific valve switching operation in step S4 until the entire volume of hot water in the connecting channel 32 flows into the hot water outlet channel 31, the time when the cumulative flow rate of the connecting channel 32 reaches the volume of the connecting channel 32 can be considered as the time when the predetermined time Ta has been reached. The cumulative flow rate can be detected, for example, by installing a flow sensor in the connecting channel 32.

[0040] Figures 3 to 5 show other embodiments of the present invention. In these figures, elements that are the same as or similar to those in the above embodiments (including steps in the flowchart) are denoted by the same reference numerals as in the above embodiments, and redundant explanations are omitted.

[0041] The hot water supply system SYa shown in Figure 3 is equipped with an instant hot water operation function. More specifically, an instant hot water supply channel 36 is provided connecting a position Pb near the hot water supply terminal 9 in the hot water outlet channel 31 and an intermediate position Pc in the common inlet channel 37a (or inlet channel 30). An instant hot water circulation pump P2 is provided in this instant hot water supply channel 36, and in the instant hot water standby state, the hot water can be circulated in a fixed circulation path by driving the instant hot water circulation pump P2. The circulation path is a path in which the hot water that has flowed between positions Pa and Pb in the hot water outlet channel 31 passes through the instant hot water supply channel 36, then further passes through the common inlet channel 37a, the multiple gas water heaters 5, the common hot water outlet channel 37b, and the connecting channel 32, and returns to the hot water outlet channel 31. In the instant hot water standby state, the hot water maintained within a predetermined temperature range circulates in the circulation path, and when the hot water supply terminal 9 is opened, the hot water immediately flows out from the hot water supply terminal 9.

[0042] In this hot water supply system SYa, the operation control shown in the flowchart in Figure 4 is performed.

[0043] Steps S1 to S4 in Figure 4 are the same as those shown in Figure 2, and their explanation will be omitted. However, after the specific valve switching operation in step S4 is performed, it is determined whether the water inlet flow rate Q2 to the auxiliary heat source device A is equal to or greater than a predetermined minimum operating flow rate Qth (S11). In this determination, if the water inlet flow rate Q2 is equal to or greater than the minimum operating flow rate Qth, the burner 50 starts driven combustion and the auxiliary heat source device A is operated appropriately, so the second on-off valve Vb remains open and the first on-off valve Va is closed (S11: YES, S6).

[0044] In contrast to the above, the water inlet flow rate Q2 to the auxiliary heat source device A may be less than the minimum operating flow rate Qth (S11:NO). The water flow path of the gas water heater 5, which constitutes the auxiliary heat source device A, is more complex and longer than the water flow path of the hot water storage tank 1, and therefore has greater flow resistance. For this reason, depending on the configuration of the auxiliary heat source device A, after a specific valve switching operation is performed, the water flow rate from the connecting flow path 32 to the hot water outlet flow path 31 may become very small and fall below the minimum operating flow rate Qth. In this case, the auxiliary heat source device A will not operate properly.

[0045] In contrast, in the above case, the value of the inflow water flow rate Q2a at that time (the value before the instant hot water circulation pump P2 is driven) is stored in the hot water flow control unit 4b, and then the instant hot water circulation pump P2 is driven. S12, S13). As a result, the water inflow rate Q2 to the auxiliary heat source device A increases to more than or equal to the minimum operating flow rate Qth, making it possible to operate the auxiliary heat source device A appropriately and supply the hot water heated by this auxiliary heat source device A to the hot water outlet channel 31 and the hot water supply terminal 9.

[0046] When the instant hot water circulation pump P2 starts operating and the inlet water flow rate Q2 becomes equal to or greater than the minimum operating flow rate Qth, the driving speed of the instant hot water circulation pump P2 is kept constant, and the hot water flow rate Qb by the instant hot water circulation pump P2 can be determined (S14:YES, S15, S16). The hot water flow rate Qb by the instant hot water circulation pump P2 can be determined by the following equation 1. Qb=Q2b-Q2a…Equation 1 Here, Q2b is the current hot water flow rate. Q2a is the hot water flow rate before the start of operation of the instant hot water circulation pump P2, whereas Q2b is the hot water flow rate after the start of operation of the instant hot water circulation pump P2.

[0047] From Equation 1, after determining the hot water flow rate Qb by the instant hot water circulation pump P2, it is determined whether the value obtained by subtracting the hot water flow rate Qb by the instant hot water circulation pump P2 from the current (latest) inlet flow rate Q2'(Q2) is greater than or equal to the minimum operating flow rate Qth ((Q2'-Qb)≧Qth?) (S17). In this determination, if (Q2'-Qb) is greater than or equal to the minimum operating flow rate Qth, the drive of the instant hot water circulation pump P2 is stopped (S17:YES, S18). Step S17 corresponds to the "determination of whether stopping the instant hot water circulation pump would cause the inlet flow rate to the auxiliary heat source device to fall below the minimum operating flow rate" of the present invention. By stopping the instant hot water circulation pump P2 after the above determination, it is possible to avoid the problem that the heating of hot water by the auxiliary heat source device A would also be stopped due to the stopping of the instant hot water circulation pump P2. After stopping the instant hot water circulation pump P2 in step S17, the process proceeds to step S6.

[0048] In the embodiment shown in Figure 5, a valve V in the form of a three-way valve is provided at the connection point between the hot water outlet channel 31 and the connecting channel 32. This valve V has a function that combines the functions of the first and second on-off valves Va and Vb described above (a configuration that substantially incorporates the first and second on-off valves Va and Vb). The same effects and advantages as in the above embodiment can be obtained with this configuration as well.

[0049] The present invention is not limited to the embodiments described above. The specific configuration of each part of the hot water supply system according to the present invention can be modified in various ways within the scope intended by the present invention.

[0050] The main heat source is not limited to a heat pump; other heat source devices can also be used. Similarly, auxiliary heat source devices are not limited to those consisting of multiple connected gas water heaters. Auxiliary heat source devices can, of course, be a single gas water heater, or other heat source devices such as oil water heaters. The specific types and arrangements of the first and second valves are not limited. [Explanation of Symbols]

[0051] SY, SYa Hot Water Supply System A Auxiliary heat source device Va, Vb First and second on-off valves (first and second valves) P2 Instant Hot Water Circulation Pump 1. Hot water storage tank 2. Heat pump (main heat source device) 30 Inlet water channel 31 Hot water outlet channel 32 Connection channel 36 Instant hot water channel 4a Hot water depletion detection unit (hot water depletion detection means) 4b Hot water distribution control section (hot water distribution control means)

Claims

1. A hot water storage tank that stores hot water heated by the main heat source device and is capable of supplying hot water to a hot water outlet channel equipped with a hot water supply terminal, This auxiliary heat source device is capable of heating hot water from an inlet channel that does not pass through the hot water storage tank, To enable hot water to be supplied from this auxiliary heat source device to the hot water outlet channel, a connecting channel is provided that branches and connects the auxiliary heat source device to the hot water outlet channel, A first valve capable of switching the hot water supply from the hot water storage tank to the hot water outlet channel on and off, A second valve capable of switching the on / off of hot water output from the auxiliary heat source device to the hot water output channel, When the hot water storage tank is about to run out of hot water, a means for determining when that is possible is provided, When the second valve is closed and the first valve is open, and hot water is being supplied from the hot water storage tank to the hot water outlet channel, and the hot water is about to run out, a specific valve switching operation is performed to open the second valve while keeping the first valve open, thereby ensuring that hot water is supplied to the hot water outlet channel from both the hot water storage tank and the auxiliary heat source device for a predetermined period of time or longer, after which the first valve is closed. A hot water supply system characterized by having the following features.

2. A hot water supply system according to claim 1, A hot water supply system in which the predetermined time is equal to or greater than the time required from the execution of the specific valve switching operation until the entire volume of hot water in the connecting channel flows into the hot water outlet channel.

3. A hot water supply system according to claim 2, The aforementioned auxiliary heat source device is configured to perform hot water heating on the condition that the water flow rate entering the auxiliary heat source device is equal to or greater than a predetermined minimum operating flow rate. A hot water supply system in which the predetermined time is equal to or greater than the time required from the time after the specific valve switching operation is performed until the water inflow rate to the auxiliary heat source device reaches or exceeds the minimum operating flow rate.

4. A hot water supply system according to claim 1, The system further includes an instant hot water channel that connects the hot water outlet channel and the cold water inlet channel, and is equipped with an instant hot water circulation pump that sends the hot water from the hot water outlet channel to the cold water inlet channel. The aforementioned auxiliary heat source device is configured to perform hot water heating on the condition that the water flow rate entering the auxiliary heat source device is equal to or greater than a predetermined minimum operating flow rate. A hot water supply system configured such that the instant hot water circulation pump is driven after the aforementioned specific valve switching operation is performed.

5. A hot water supply system according to claim 4, The hot water supply system is configured such that the instant hot water circulation pump starts operating when the water flow rate into the auxiliary heat source device falls below the minimum operating flow rate after the specific valve switching operation has been performed.

6. A hot water supply system according to claim 4 or 5, A hot water supply system configured such that, after the instant hot water circulation pump is started in response to the execution of the aforementioned specific valve switching operation, it is determined whether stopping the instant hot water circulation pump would cause the water inflow to the auxiliary heat source device to fall below the minimum operating flow rate, and if it is determined that the flow rate will not fall below the minimum operating flow rate, the instant hot water circulation pump is stopped.

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