Hot water system

Abstract

To provide a hot water system capable of properly preventing or restraining high-temperature tap due to an after-boiling phenomenon in a heat exchanger when an operation of a sub hot water supplier is turned off.SOLUTION: In a hot water system SY, under a condition that a sub hot water supplier Ab is made to an operation-off condition from an operation-on condition and driving-combustion of a burner 4 stopped, when outlet side temperature of a heat exchanger 3 becomes higher than predetermined first temperature, a heat exchanger flow rate control valve Vb is switched to an opening condition that a valve closing operation is cancelled and a specific condition that how water circulation occurs to the heat exchanger 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hot water supply system of a type in which a plurality of hot water heaters are combined.

Background Art

[0002] As a specific example of a hot water supply system, there is one described in Patent Document 1. The hot water supply system described in the same document includes a plurality of hot water heaters capable of discharging hot water into a shared hot water supply path connected to a hot water supply destination. These plurality of hot water heaters are classified into a main hot water heater whose operation is first started at the start of hot water supply, and a sub hot water heater whose operation is turned on and off in response to the presence or absence of a predetermined replenishment request during the operation of the main hot water heater. The hardware configurations of the main hot water heater and the sub hot water heater themselves are the same as, for example, those of a general gas hot water heater. That is, each hot water heater can heat the hot and cold water supplied from the outside by guiding it to a heat exchanger via a water inlet passage and then heating it with a burner. This heated hot and cold water passes through a hot water discharge passage and is guided to a hot water discharge port, but the hot water discharge passage and the water inlet passage are connected via a bypass passage, and a part of the unheated hot and cold water in the water inlet passage can be mixed into the heated hot water in the hot water discharge passage. Near the outlet of the heat exchanger in the hot water discharge passage (the upstream part from the connection point of the bypass passage), and in the bypass passage, a heat exchanger flow rate adjustment valve (commonly referred to as a can body flow rate adjustment valve) and a bypass flow rate adjustment valve are respectively provided. According to such a configuration, it is possible to control the mixing ratio of the heated hot water that has passed through the heat exchanger and the unheated hot and cold water that has passed through the bypass passage, and to bring the hot water discharge temperature close to a desired target hot water discharge temperature.

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

[0004] That is, when both the main water heater and the sub-water heater of a conventional water supply system are in the driving combustion state, and there is no longer a replenishment request for the sub-water heater, the sub-water heater should be set to the off operation state, and the valve closing operation of its heat exchanger flow rate adjustment valve is started. Here, the heat exchanger flow rate adjustment valve is generally an electric valve using, for example, a stepping motor or the like, and it takes a certain amount of time (for example, several seconds or more) to reach the fully closed state from the fully open or nearly fully open valve opening state. On the other hand, when the heat exchanger flow rate adjustment valve starts the valve closing operation and the heat exchanger flow rate decreases below a predetermined value, the driving combustion of the burner stops, the bypass flow rate adjustment valve also starts the valve closing operation, and the sub-water heater enters the complete off operation state. However, even in such an off operation state, there is a risk of a "post-boiling phenomenon" in which the hot water in the heat exchanger is heated by the residual heat of the heat exchanger and becomes high temperature. Therefore, after the operation of the sub-water heater stops, if this sub-water heater receives a replenishment request and is immediately restarted, there is a risk that the hot water that has become high temperature due to the post-boiling phenomenon will be supplied to the hot water supply destination. It is desirable to appropriately eliminate such a situation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been conceived under the above circumstances, and appropriately prevents or suppresses the hot water outlet temperature from becoming high due to the post-boiling phenomenon in the heat exchanger when the sub-water heater is turned off. Its problem is to provide a hot water supply system that can achieve this. stop or suppress it.

Means for Solving the Problem

[0007] In order to solve the above problems, the present invention takes the following technical means.

[0008] The hot water supply system provided by the present invention includes a plurality of hot water heaters capable of discharging hot water into a shared hot water supply path connected to a hot water supply destination. As these plurality of hot water heaters, it is divided into a main hot water heater whose operation is first started at the start of hot water supply, and a sub-hot water heater whose operation is turned on and off corresponding to the presence or absence of a predetermined replenishment request during the operation of the main hot water heater. The sub-hot water heater includes a water inlet passage that guides the hot water supplied from the outside to a heat exchanger, a burner capable of heating the hot water flowing into the heat exchanger, a hot water outlet passage that guides the hot water heated in the heat exchanger to a hot water outlet connected to the hot water supply path, a bypass passage capable of mixing a part of the hot water in the water inlet passage with the hot water in the hot water outlet passage, a heat exchanger flow rate adjustment valve and a bypass flow rate adjustment valve capable of adjusting the hot water flow rates of the heat exchanger and the bypass passage respectively. When the sub-hot water heater is in the on state of operation and the burner is driving and burning while hot water is flowing through the heat exchanger, when the replenishment request is absent and the operation is turned off, the heat exchanger flow rate adjustment valve and the bypass flow rate adjustment valve perform a valve closing operation, and the driving and burning of the burner are stopped. It is a hot water supply system configured as such. When the sub-hot water heater changes from the on state of operation to the off state of operation and the driving and burning of the burner are stopped, when the temperature on the outlet side of the heat exchanger rises above a predetermined first temperature, the heat exchanger flow rate adjustment valve is switched to an open state in which the valve closing operation is canceled, and a specific state in which hot water flows through the heat exchanger is set.

[0009] According to such a configuration, the following effects can be obtained. That is, when the sub-boiler changes from the operating-on state to the operating-off state and the driving combustion of the burner has stopped, hot water heating may be performed by the residual heat of the heat exchanger, and the temperature on the outlet side of the heat exchanger may rise above a predetermined first temperature. In this case, the heat exchanger flow rate adjustment valve is switched to an open state in which the valve closing operation is canceled, and a specific state in which hot water flows through the heat exchanger is set. When such a state is set, unlike the case where the hot water in the heat exchanger is heated by the residual heat while remaining stationary and stagnant, the hot water in the heat exchanger can be prevented from being heated to too high a temperature. From this, according to the present invention, it is possible to appropriately prevent or suppress the problem that the hot water temperature becomes high due to the after-boiling phenomenon in the heat exchanger when the sub-boiler is turned off.

[0010] In the present invention, preferably, the specific state ends when the temperature on the outlet side of the heat exchanger drops below a predetermined second temperature, when the duration of the specific state reaches a predetermined time, or when the integrated hot water flow rate in the heat exchanger during the specific state reaches a predetermined flow rate, and thereafter the heat exchanger flow rate adjustment valve is configured to be in a closed state.

[0011] According to such a configuration, it is appropriately avoided that the set period of the specific state continues unnecessarily long.

[0012] In the present invention, preferably, data processing means for calculating a theoretical hot water temperature calculated based on the hot water flow rate and the outlet side temperature on the outlet side of the heat exchanger, and the bypass flow rate and the hot water temperature in the bypass passage is further provided, and during the period of the specific state, the bypass flow rate adjustment valve is configured to perform flow rate adjustment to bring the theoretical hot water temperature closer to the target hot water temperature.

[0013] According to such a configuration, since control is performed to bring the hot water temperature closer to the target hot water temperature, it is more appropriately prevented that the hot water temperature becomes much higher than the target hot water temperature. Here, and As an important point, according to the above configuration, the outlet water temperature to be controlled is not the measured value of the water temperature (outlet water temperature) after the water passing through the two paths of the water heated by passing through the heat exchanger and the water passing through the bypass flow path are mixed, but the theoretical outlet water temperature. This theoretical outlet water temperature is calculated based on predetermined physical parameters before the water of the two paths is mixed. However, this theoretical outlet water temperature is not the one obtained by feedback of the measured value of the outlet water temperature, but is calculated at a stage before the water of the two paths is mixed and discharged as outlet water. Therefore, it is more preferable to make the control for bringing the theoretical outlet water temperature closer to the target outlet water temperature excellent in speed and responsiveness and to prevent high-temperature outlet water.

[0014] In the present invention, preferably, the bypass flow rate adjustment valve is configured to end the flow rate adjustment for bringing the theoretical outlet water temperature closer to the target outlet water temperature and start the valve closing operation when the specific state ends.

[0015] According to such a configuration, after the specific state ends, it is possible to appropriately prevent the bypass flow rate adjustment valve from being in an inappropriate open state and prevent the water from flowing through the bypass flow path improperly.

[0016] Other features and advantages of the present invention will become clearer from the following description of the embodiments of the invention with reference to the accompanying drawings.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0018] Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

[0019] The hot water supply system SY shown in FIG. 1 includes a plurality of hot water heaters A and a control unit (central control unit) 60 additionally installed for the plurality of hot water heaters A to execute operation control thereof. Each of the plurality of hot water heaters A includes a water inlet 10 through which water enters from the outside via a water supply pipe 20, and a hot water outlet 11 that is connected to a shared hot water supply path 21 leading to a plurality of hot water supply terminals 8 and through which hot water can be discharged to the hot water supply path 21.

[0020] When hot water supply is started in the hot water supply system SY, the plurality of hot water heaters A are divided into a main hot water heater Aa (A) that starts operation first and a sub - hot water heater Ab (A) whose operation is turned on or off according to the presence or absence of a replenishment request during the operation of the main hot water heater Aa. In FIG. 1, one main hot water heater Aa and two sub - hot water heaters Ab are shown, but the numbers are not limited, and there should be at least one main hot water heater Aa and at least one sub - hot water heater Ab.

[0021] The control unit 60 differentiates between the main hot water heater Aa and the sub - hot water heater Ab and sets whether there is a replenishment request to the sub - hot water heater Ab. When many hot water supply terminals 8 are in an open state and the hot water demand cannot be met by the operation of only the main hot water heater Aa, a replenishment request is made to the sub - hot water heater Ab under the control of the control unit 60, and the sub - hot water heater Ab starts operation. Then, when the plurality of hot water supply terminals 8 are sequentially closed, the replenishment request to the sub - hot water heater Ab is cancelled, and the operation of the sub - hot water heater Ab is turned off. The control unit 60 is configured using a microcomputer or the like (the same applies to the control unit 6 described later) and is housed in a housing (not shown) installed outside the plurality of hot water heaters A. However, alternatively, it is also possible to adopt a configuration incorporated in the exterior case 5 of the main hot water heater Aa, for example.

[0022] ​The main water heater Aa and the sub water heater Ab have the same basic hardware configuration as a conventionally known gas water heater. Hereinafter, the sub water heater Ab will be briefly described (see also Fig. 2). Note that since the main water heater Aa has the same hardware configuration as the sub water heater Ab, its description will be omitted. The reference numerals of each part of the main water heater Aa in Fig. 1 are used as the corresponding reference numerals for the sub water heater Ab.

[0023] The sub water heater Ab includes a water inlet passage 12 capable of guiding the hot water and cold water that has entered the water inlet 10 from the water supply pipe 20 to the heat exchanger 3, a burner 4 for heating the hot water and cold water that has flowed into the heat exchanger 3, a hot water outlet passage 13 for guiding the hot water and cold water heated in the heat exchanger 3 to the hot water outlet 11, and a bypass passage 14. The bypass passage 14 connects intermediate portions between the water inlet passage 12 and the hot water outlet passage 13, and a part of the unheated hot water and cold water flowing through the water inlet passage 12 passes through this bypass passage 14 and is mixed with the hot water and cold water flowing through the hot water outlet passage 13, and the hot water outlet temperature at the hot water outlet 11 can be controlled by this mixing. As means for realizing such control, in addition to the control unit 6, the sub water heater Ab further includes a heat exchanger flow rate adjustment valve Vb and a bypass flow rate adjustment valve Va capable of respectively adjusting the hot water and cold water flow rates of the heat exchanger 3 and the bypass passage 14. These heat exchanger flow rate adjustment valve Vb and bypass flow rate adjustment valve Va are, for example, electric valves using a stepping motor. The sub water heater Ab also includes temperature sensors Sa to Sc for respectively detecting the water inlet temperature to the heat exchanger 3, the outlet side temperature of the heat exchanger 3, and the hot water outlet temperature from the hot water outlet 11, and flow rate sensors Sd and Se for respectively detecting the flow rate passing through the heat exchanger 3 (outlet side flow rate) and the bypass flow rate. The control unit 6 can execute operation control and data processing of each part of the sub water heater Ab, and executes the control described later in response to, for example, the presence or absence of a complement request from the control unit 60 (central control unit).

[0024] Next, an example of operation control in the above-described water supply system SY and the effects will be described with reference to the flowchart of Fig. 3.

[0025] First, when, with the main water heater Aa in the on state, the main water heater Aa alone cannot meet the hot water demand, the sub water heater Ab (for example, one of a plurality of sub water heaters Ab) receives a replenishment request from the control unit 60 (S1: YES). Then, this sub water heater Ab is turned on (S2). In this on state, the heat exchanger flow rate adjustment valve Vb starts a valve opening operation, and when the hot water flow rate in the heat exchanger 3 becomes equal to or higher than a predetermined minimum operating flow rate, the burner 4 starts driving combustion. At that time, the bypass flow rate is adjusted by the bypass flow rate adjustment valve Va, and control is executed to bring the hot water outlet temperature closer to a desired target hot water outlet temperature.

[0026] In the above-described on state, when the hot water demand decreases and there is no replenishment request (S3: YES), the sub water heater Ab is switched off. When switching to this off state, first, the valve closing operation of the heat exchanger flow rate adjustment valve Vb is started (S4). Also, due to this valve closing operation, when the hot water flow rate in the heat exchanger 3 decreases to less than a predetermined flow rate, the bypass flow rate adjustment valve Va starts a valve closing operation (S5: YES, S6). Further, when the hot water flow rate in the heat exchanger 3 decreases to less than the minimum operating flow rate, the driving combustion of the burner 4 stops (S7: YES, S8).

[0027] On the other hand, in the control unit 6 (or the control unit 60), it is determined whether the temperature on the outlet side of the heat exchanger 3 detected using the temperature sensor Sb has risen above a predetermined first temperature (S9). Even after the driving combustion of the burner 4 stops, if a post-boiling phenomenon occurs in which the hot water in the heat exchanger 3 and its vicinity is heated by the residual heat of the heat exchanger 3 and becomes hot, the temperature on the outlet side of the heat exchanger 3 rises above the first temperature. When such a phenomenon occurs, the heat exchanger flow rate adjustment valve Vb is switched to an open state in which the valve closing operation that has been executed so far is canceled, and a state (specific state) in which hot water flows through the heat exchanger 3 is set (S9: YES, S10). Note that the "open state where the valve closing operation is canceled" may refer to either the first case where the heat exchanger flow rate adjustment valve Vb is in the middle of the valve closing operation and the operation is stopped to maintain the open state, or the second case where the heat exchanger flow rate adjustment valve Vb is set to the open state again when the valve closing operation of the heat exchanger flow rate adjustment valve Vb has already been completed. In the second case, the heat exchanger flow rate adjustment valve Vb is not fully opened, but is, for example, in an open state about 30% of the fully open state.

[0028] As described above, when hot water is circulated through the heat exchanger 3, the post-boiling phenomenon in which the hot water in the heat exchanger 3 is heated to a high temperature by the residual heat while remaining stagnant is appropriately prevented or suppressed. As a result, when there is a subsequent immediate replenishment request and the operation of the sub-feed water heater Ab is restarted, it is possible to prevent improper high-temperature hot water discharge caused by the post-boiling phenomenon.

[0029] In step S10, when the specific state is set, the bypass flow rate adjustment valve Va cancels the valve closing operation and resumes the flow rate adjustment to bring the hot water discharge temperature closer to the target hot water discharge temperature (S11). As a result, it is more appropriately prevented that the hot water discharge temperature becomes significantly higher than the target hot water discharge temperature. Preferably, the hot water discharge temperature at that time is the theoretical hot water discharge temperature calculated based on the hot water flow rate Qa [L / min] on the outlet side of the heat exchanger 3, the outlet side temperature Ta [°C], the bypass flow rate Qb [L / min] in the bypass flow path 14, and the hot water temperature (inlet water temperature) Tb [°C] thereof. The control unit 6 (or the control unit 60) that calculates this theoretical hot water discharge temperature corresponds to a specific example of the data processing means referred to in the present invention.

[0030] The following formula 1 is a specific example of the calculation formula for the theoretical hot water discharge temperature. Theoretical hot water discharge temperature [°C] = (Qa·Ta + Qb·Tb) / (Qa + Qb) … Formula 1

[0031] If the above-described theoretical hot water outlet temperature is adopted as the hot water outlet temperature, the hot water outlet temperature can be detected quickly (in advance) compared with the case where the hot water outlet temperature is actually measured using the temperature sensor Sc, and the hot water outlet temperature control by the bypass flow rate adjustment valve Va can be accurately executed with good responsiveness. Therefore, it is more preferable for preventing high-temperature hot water from flowing out of the hot water outlet 11. However, in the present invention, instead of the above-described theoretical hot water outlet temperature, the actually measured value of the hot water outlet temperature detected using the temperature sensor Sc may be adopted.

[0032] Thereafter, when the temperature on the outlet side of the heat exchanger 3 drops below a predetermined second temperature, the valve closing operation of the heat exchanger flow rate adjustment valve Vb is restarted to end the specific state in which hot water flows through the heat exchanger 3 (S12: YES, S13). Also, the valve closing operation of the bypass flow rate adjustment valve Va is restarted (S14). By performing such a valve closing operation, when the sub-boiler Ab is in the off state of operation, it is appropriately avoided that hot water passes through each part of the sub-boiler Ab. In step S9, when the temperature on the outlet side of the heat exchanger 3 does not rise above the first temperature and such a state does not occur even after a predetermined time has elapsed since the sub-boiler Ab was turned off, the above-described control for coping with after-boiling is not executed (S9: NO, S15: YES, return).

[0033] The present invention is not limited to the contents of the above-described embodiments. The specific configuration of each part of the hot water supply system according to the present invention can be variously designed and changed within the scope intended by the present invention.

[0034] In steps S12 and S13, when the temperature on the outlet side of the heat exchanger drops below a predetermined second temperature, it is configured to end a predetermined specific state, but the present invention is not limited to this. Instead of the above configuration, for example, when the duration of the specific state reaches a predetermined time, or when the integrated flow rate of hot water in the heat exchanger during the specific state reaches a predetermined flow rate, the specific state can also be configured to end.

[0035] The specific values of the predetermined first temperature and second temperature referred to in the present invention are not limited. Also, it is possible to adopt a configuration in which these values can be appropriately changed by a switch operation or the like. In the present invention, the specific control method and its mode, such as which of the plurality of water heaters is to be the main water heater and which is to be the sub water heater, are not limited. As already described, the specific number of the plurality of water heaters is also not limited. Each water heater can be, for example, an oil water heater instead of a gas water heater.

Explanation of Signs

[0036] SY Water supply system Aa(A) Main water heater (water heater) Ab(A) Sub water heater (water heater) Sa~Sc Temperature sensor Sd,Se Flow rate sensor Va Bypass flow rate adjustment valve Vb Heat exchanger flow rate adjustment valve 10 Water inlet 11 Hot water outlet 12 Water inlet passage 13 Hot water outlet passage 14 Bypass passage 21 Hot water supply passage 3 Heat exchanger 4 Burner 6,60 Control unit (data processing means) 8 Hot water supply terminal

Claims

1. Comprising a plurality of water heaters capable of discharging hot water into a shared hot water supply path connected to the hot water outlet, Among these plurality of water heaters, it is divided into a main water heater whose operation is first started at the start of hot water supply, and a sub water heater whose operation is turned on and off corresponding to the presence or absence of a predetermined replenishment requirement during the operation of the main water heater, The sub water heater includes an inlet water path for guiding the hot and cold water supplied from the outside to the heat exchanger, a burner capable of heating the hot and cold water flowing into the heat exchanger, an outlet water path for guiding the hot and cold water heated in the heat exchanger to the hot water outlet connected to the hot water supply path, a bypass flow path capable of mixing a part of the hot and cold water in the inlet water path with the hot and cold water in the outlet water path, and a heat exchanger flow rate adjustment valve and a bypass flow rate adjustment valve capable of respectively adjusting the hot and cold water flow rates in the heat exchanger and the bypass flow path, When the sub water heater is in the on state of operation and the burner is driving and burning while the hot and cold water is flowing through the heat exchanger, when the replenishment requirement disappears and the operation is turned off, the heat exchanger flow rate adjustment valve and the bypass flow rate adjustment valve perform a valve closing operation, and the driving and burning of the burner is configured to stop. A hot water supply system, When the sub water heater changes from the on state of operation to the off state of operation and the driving and burning of the burner has stopped, when the temperature on the outlet side of the heat exchanger rises above a predetermined first temperature, the heat exchanger flow rate adjustment valve is switched to an open state in which the valve closing operation is canceled, and a specific state in which hot and cold water flows through the heat exchanger is configured to be set. A hot water supply system characterized by this.

2. The hot water supply system according to Claim 1, The specific state ends when the temperature on the outlet side of the heat exchanger drops below a predetermined second temperature, when the duration of the specific state reaches a predetermined time, or when the integrated hot and cold water flow rate in the heat exchanger during the specific state reaches a predetermined flow rate, and thereafter the heat exchanger flow rate adjustment valve is configured to be in a closed state. A hot water supply system.

3. The hot water supply system according to Claim 1, Further comprising data processing means for calculating the theoretical hot water discharge temperature calculated based on the hot and cold water flow rate and the outlet side temperature on the outlet side of the heat exchanger, and the bypass flow rate and the hot and cold water temperature in the bypass flow path, During the period of the specific state, the bypass flow rate adjustment valve is configured to perform flow rate adjustment to bring the theoretical hot water outlet temperature closer to the target hot water outlet temperature. A hot water supply system.

4. The hot water supply system according to claim 3, The bypass flow rate adjustment valve is configured to terminate the flow rate adjustment to bring the theoretical hot water outlet temperature closer to the target hot water outlet temperature and start a valve closing operation when the specific state ends. A hot water supply system.

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