Hot water system

Abstract

To provide a hot water system capable of properly preventing or restraining high-temperature tap due to an improper tap temperature control when an operation of a sub hot water supplier is turned off.SOLUTION: In a hot water system SY, based on no compensation request under a condition that an operation of a sub hot water supplier Ab is turned on, after a heat exchanger flow rate control valve Vb and a bypass flow rate control valve Va start a valve closing operation and when a specific condition that tap temperature exceeds predetermined temperature higher than target tap temperature occurs, the bypass flow rate control valve Va stops the valve closing operation already being executed, and starts a flow rate control for making the tap temperature near the target tap temperature.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 water supplied from the outside by guiding it to a heat exchanger via a water inlet passage and then heating it with a burner. The heated hot 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 non-heated hot 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 non-heated hot 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 prior art, as described below, there was room for improvement.

[0004] That is, when both the main water heater and the sub water heater are in driving combustion, when the replenishment requirement for the sub water heater disappears, in the sub water heater, the valve closing operation of the heat exchanger flow rate adjustment valve is started so as to be in the off operation state. 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 close 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 is stopped. As a result, the bypass flow rate adjustment valve also starts the valve closing operation, and the control of the hot water outlet temperature is no longer performed. For this reason, when the heat exchanger flow rate adjustment valve has not yet been fully closed, the valve closing operation of the bypass flow rate adjustment valve is started, resulting in a situation where the hot water outlet temperature control is not properly executed, and there is a risk of generating hot water (high-temperature hot water) that is much higher than the target hot water outlet temperature. It is desirable to appropriately resolve 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 circumstances as described above, and an object of the present invention is to provide a hot water supply system capable of appropriately preventing or suppressing high-temperature hot water caused by improper execution of hot water outlet temperature control when turning off the sub water heater.

Means for Solving the Problems

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

[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 switched on and off corresponding to the presence or absence of a predetermined replenishment requirement during the operation of the main hot water heater. The sub hot water heater includes a water inlet path that guides the hot water supplied from the outside to the heat exchanger, a burner capable of heating the hot water flowing into the heat exchanger, a hot water outlet path that guides the hot water heated in the heat exchanger to a hot water outlet connected to the hot water supply path, a bypass flow path capable of mixing a part of the hot water in the water inlet path with the hot water in the hot water outlet path to control the hot water discharge temperature at the hot water outlet, and 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 flow path respectively. When the sub hot water heater is in the operation-on state and the burner is driven and burning while the hot 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 are configured to perform a valve closing operation. A hot water supply system, characterized in that when a specific state occurs in which the hot water discharge temperature exceeds a predetermined temperature higher than the target hot water discharge temperature after the heat exchanger flow rate adjustment valve and the bypass flow rate adjustment valve start the valve closing operation based on the fact that there is no replenishment requirement when the sub hot water heater is in the operation-on state, the bypass flow rate adjustment valve stops the valve closing operation and performs a flow rate adjustment to bring the hot water discharge temperature closer to the target hot water discharge temperature.

[0009] According to such a configuration, the following effects can be obtained. That is, when there is no replenishment request during the operation-on state of the sub-water heater, after the heat exchanger flow rate adjustment valve and the bypass flow rate adjustment valve each start the valve closing operation, the hot water outlet temperature control is substantially completed. Therefore, a specific state may occur where the hot water outlet temperature exceeds a predetermined temperature higher than the target hot water outlet temperature. In this case, the bypass flow rate adjustment valve stops the valve closing operation and adjusts the flow rate to bring the hot water outlet temperature closer to the target hot water outlet temperature. Therefore, the state where the hot water outlet temperature remains at a high temperature exceeding the predetermined temperature is quickly eliminated, and it becomes possible to appropriately prevent or suppress high-temperature hot water discharge when the sub-water heater is turned off.

[0010] In the present invention, preferably, data processing means for calculating a theoretical hot water outlet temperature calculated based on the hot water flow rate and the outlet temperature on the outlet side of the heat exchanger, and the bypass flow rate and the hot water temperature in the bypass flow path is further provided, and the theoretical hot water outlet temperature is adopted as the hot water outlet temperature.

[0011] According to such a configuration, the hot water outlet temperature to be controlled is not the measured value (actual measured value) of the hot water temperature (hot water outlet temperature) after the hot water passing through the heat exchanger and the hot water passing through the bypass flow path are mixed, but the theoretical hot water outlet temperature. This theoretical hot water outlet temperature is calculated based on predetermined physical parameters before the hot water in the two paths is mixed, and is not the feedback of the measured value of the hot water outlet temperature, but is calculated at a stage before the hot water in the two paths is mixed and discharged as hot water. Therefore, the rapidity and responsiveness of the operation for preventing high-temperature hot water discharge are excellent, which is more preferable for preventing high-temperature hot water discharge.

[0012] In the present invention, preferably, the hot water outlet temperature is a measured value using a temperature sensor.

[0013] According to such a configuration, since it is not necessary to calculate the theoretical hot water outlet temperature, it is possible to simplify the control program of the hot water supply system.

[0014] In the present invention, preferably, when the specific state occurs, the bypass flow rate adjustment valve stops the valve closing operation, and when the valve closing operation of the heat exchanger flow rate adjustment valve is completed during the period of performing flow rate adjustment to bring the hot water outlet temperature closer to the target hot water outlet temperature, it is configured to resume the valve closing operation.

[0015] According to such a configuration, after the valve closing operation of the heat exchanger flow rate adjustment valve is completed, it is possible to prevent the bypass flow rate adjustment valve from being in a wasteful or inappropriate open state, and appropriately prevent hot and cold water from flowing through the bypass passage improperly.

[0016] 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

[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 supply devices A, and a control unit (central control unit) 60 additionally installed for the plurality of hot water supply devices A to execute operation control of these plurality of hot water supply devices A. Each of the plurality of hot water supply devices 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 connected to a shared hot water supply path 21 connected to a plurality of hot water supply terminals 8 and capable of discharging hot water to the hot water supply path 21.

[0020] When hot water supply is started in this hot water supply system SY, the plurality of hot water heaters A are classified into a main hot water heater Aa (A) whose operation is started 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 these numbers are not limited, and at least one main hot water heater Aa and sub-hot water heater Ab are sufficient.

[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 only by the operation of 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 operating. 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 (similarly for 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 basic hardware configuration of the main hot water heater Aa and the sub-hot water heater Ab is the same as that of a conventionally known gas hot water heater. Hereinafter, the sub-hot water heater Ab will be briefly described (see also FIG. 2). Since the main hot water heater Aa has the same hardware configuration as the sub-hot water heater Ab, its description will be omitted. The reference numerals of the respective parts of the main hot water heater Aa in FIG. 1 are used as the reference numerals corresponding to the sub-hot water heater Ab.

[0023] The sub-water heater Ab includes a water inlet passage 12 capable of guiding the hot 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 that has flowed into the heat exchanger 3, a hot water outlet passage 13 for guiding the hot 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. A part of the unheated hot water flowing through the water inlet passage 12 passes through this bypass passage 14 and is mixed with the hot 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 that can respectively adjust the hot 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 is capable of executing operation control, data processing, etc. of each part of the sub-water heater Ab, and executes the control described later in response to the presence or absence of a complement request from the control unit 60 (central control unit).

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

[0025] First, when the main water heater Aa is in the on state and the main water heater Aa alone cannot meet the hot and cold water demand, the sub water heater Ab (for example, one of the 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 and cold water flow rate in the heat exchanger 3 reaches or exceeds 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 outlet water temperature closer to the desired target outlet water temperature. In the case of controlling the outlet water temperature during normal operation, the outlet water temperature as the control target may be either the measured value of the outlet water temperature detected using the temperature sensor Sc or the theoretical outlet water temperature described later.

[0026] In the above-mentioned on state, when the hot and cold 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 and cold water flow rate in the heat exchanger 3 decreases below a predetermined flow rate, the bypass flow rate adjustment valve Va starts a valve closing operation (S5: YES, S6).

[0027] On the other hand, in the control unit 6 (or control unit 60), it is determined whether the outlet water temperature has risen to a temperature exceeding a predetermined temperature that is higher than the target outlet water temperature (S7). After the valve closing operation of the bypass flow rate adjustment valve Va is started, in some cases, high-temperature outlet water may occur as a result of inappropriate execution of the outlet water temperature control, and the presence or absence of such a situation is appropriately determined in the control unit 6.

[0028] Preferably, the outlet water temperature in step S7 described above is the following theoretical outlet water temperature. That is, the theoretical outlet water temperature is the theoretical outlet water temperature calculated based on the hot and cold water flow rate Qa [L / min] on the outlet side of the heat exchanger 3, the outlet side temperature Ta [°C], as well as the bypass flow rate Qb [L / min] and its hot and cold water temperature (inlet water temperature) Tb [°C] in the bypass flow path 14. The control unit 6 (or control unit 60) that calculates this theoretical hot water outlet temperature corresponds to a specific example of the data processing means referred to in the present invention.

[0029] The following formula 1 is a specific example of the calculation formula for the theoretical hot water outlet temperature. Theoretical hot water outlet temperature [°C] = (Qa·Ta + Qb·Tb) / (Qa + Qb) … Formula 1

[0030] If the above-mentioned theoretical hot water outlet temperature is adopted as the hot water outlet temperature, compared with the case of measuring the hot water outlet temperature using the temperature sensor Sc, it is possible to quickly (in advance) detect that the hot water outlet temperature becomes high, and it is possible to be excellent in responsiveness when taking measures to prevent high-temperature hot water outlet. However, in the present invention, instead of the above-mentioned theoretical hot water outlet temperature, the measured value of the hot water outlet temperature detected using the temperature sensor Sc may be adopted.

[0031] In step S7, when it is determined that a specific state occurs in which the hot water outlet temperature (theoretical hot water outlet temperature) exceeds the predetermined temperature, the bypass flow rate adjustment valve Va stops the valve closing operation and starts flow rate adjustment to bring the hot water outlet temperature (theoretical hot water outlet temperature) closer to the target hot water outlet temperature (S7: YES, S8). As a result, the occurrence of high-temperature hot water outlet can be appropriately prevented or suppressed, and the hot water supply temperature to the hot water supply terminal 8 can be stabilized.

[0032] When the hot water flow rate of the heat exchanger 3 decreases below the minimum operating flow rate, the driving combustion of the burner stops (S9: YES, S10). After that, when the heat exchanger flow rate adjustment valve Vb is in the fully closed state, the flow of hot water from the heat exchanger 3 to the hot water outlet 11 stops, and there is no need for hot water outlet temperature control. For this reason, at that time, the bypass flow rate adjustment valve Va ends the flow rate adjustment for hot water outlet temperature control and resumes the valve closing operation (S11: YES, S12, return).

[0033] On the other hand, unlike the above, in step S7, if it is not determined that a specific state where the hot water temperature exceeds a predetermined temperature has occurred, and the hot water flow rate of the heat exchanger 3 decreases below the minimum operating flow rate, the driving combustion of the burner stops (S7: NO, S13: YES, S14). When the heat exchanger flow rate adjustment valve Vb is fully closed, the operation of step S8 described above is not executed, and the process returns (S15: YES, return).

[0034] 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 freely designed and changed in various ways within the scope intended by the present invention.

[0035] In the present invention, based on the fact that there is no replenishment request when the sub-hot water heater is in the operating-on state, after the heat exchanger flow rate adjustment valve starts the valve closing operation, a case where the hot water temperature exceeds a predetermined temperature higher than the target hot water temperature is defined as a specific state. However, the specific value of the predetermined temperature is not limited. The predetermined temperature can be configured to be appropriately changeable, for example, by a switch operation by the user or the like. In the present invention, the specific control method and its mode, such as which of the plurality of hot water heaters is the main hot water heater and which is the sub-hot water heater, are not limited. As already described, the specific number of the plurality of hot water heaters is also not limited. Each hot water heater can be, for example, an oil hot water heater instead of a gas hot water heater.

Explanation of Reference Numerals

[0036] SY Hot water supply system Aa(A) Main hot water heater (hot water heater) Ab(A) Sub-hot water heater (hot water heater) Sa~Sc Temperature sensor Sd,Se Flow 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 flow path 21 Hot water supply path 3 Heat exchanger 4 Burner 6, 60 Control unit (data processing means) 8 Hot water supply terminal

Claims

1. It is provided with a plurality of water heaters capable of discharging hot water into a shared hot water supply path connected to a hot water supply destination, Among these plurality of water heaters, it is classified 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 switched on and off corresponding to the presence or absence of a predetermined replenishment request during the operation of this main water heater. The sub water heater includes an inlet water path for guiding the hot and cold water supplied from the outside to a 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 an outlet for discharging hot water 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 to control the hot water discharge temperature at the hot water outlet, 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 operation-on state and the burner is driving and burning while hot and cold 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 are configured to perform a valve closing operation. A hot water supply system, Based on the fact that the replenishment request is absent when the sub water heater is in the operation-on state, after the heat exchanger flow rate adjustment valve and the bypass flow rate adjustment valve start the valve closing operation, when a specific state occurs in which the hot water discharge temperature exceeds a predetermined temperature higher than the target hot water discharge temperature, the bypass flow rate adjustment valve stops the valve closing operation and is configured to perform a flow rate adjustment to bring the hot water discharge temperature closer to the target hot water discharge temperature. A hot water supply system characterized by this.

2. The hot water supply system according to claim 1, It further includes data processing means for calculating a 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. A hot water supply system in which the theoretical hot water discharge temperature is adopted as the hot water discharge temperature.

3. The hot water supply system according to claim 1, The hot water discharge temperature is a measured value using a temperature sensor. A hot water supply system.

4. The hot water supply system according to any one of claims 1 to 3, The bypass flow rate adjustment valve is configured to resume the valve closing operation when the valve closing operation of the heat exchanger flow rate adjustment valve is completed during a period in which the valve closing operation is stopped based on the occurrence of the specific state and the flow rate is adjusted to bring the outlet water temperature closer to the target outlet water temperature. A hot water supply system.

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