Hot water heater and hot water supply system

Abstract

To appropriately set a termination condition of instant hot water operation of a hot water supply device.SOLUTION: When a hot water tap 200 starts hot water operation in response to a temperature drop of fluid during stop of hot water supply, a controller 10 operates a circulation pump 80 at a constant output until a minimum drive time elapses, and also operates a heating mechanism that performs heating with a combustion mechanism 30. The minimum drive time is set based on a flow rate detection value Qf detected by a flow rate detector 75 under a condition that the circulation pump 80 operates at the predetermined constant output to form a hot water circulation path.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water heater and a hot water supply system, and more particularly to a water heater and a hot water supply system having an instant hot water operation function. [Background technology]

[0002] One type of water heater has a so-called instant hot water operation function that outputs hot water at the appropriate temperature immediately after hot water supply starts, even after the hot water supply has been stopped for a long time. To achieve instant hot water operation, it is necessary to operate the circulation pump even when the hot water supply is stopped (standby) and form a circulation flow path that passes through the heat source.

[0003] Patent Publication No. 2021-183889 (Patent Document 1) describes a hot water supply system that can set the conditions for ending instant hot water operation, i.e., the conditions for turning off the circulation pump and the combustion burner, in order to achieve instant hot water operation with low energy consumption.

[0004] Specifically, in the hot water supply system of Patent Document 1, the flow rate integrated value is counted when instant hot water operation is performed during trial operation, and the count value from the start of the instant hot water operation to the rise in the temperature detected by the temperature sensor is obtained as an approximate value of the capacity of the circulation flow path during instant hot water operation.

[0005] Furthermore, it is described that in actual instant hot water operation, the instant hot water operation is terminated when the integrated flow rate value from the start of the instant hot water operation reaches an end determination value set using an approximate value of the circulation flow path capacity obtained in a trial run. In particular, Patent Document 1 describes that instant hot water operation in eco mode can be achieved by setting an end determination value smaller than the approximate value (for example, 1 / 2 times). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-183889 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Document 1, it is necessary to perform instant hot water operation during a test run to set the termination conditions for the instant hot water operation, which raises concerns that the test run time will be long. Furthermore, depending on the temperature distribution in the circulation path during instant hot water operation before the test run is performed, there is a risk that the capacity of the circulation flow path will be detected as being too small.

[0008] If the end judgment value for the measurement operation is set according to an underdetected circulation flow path capacity, there is a concern that the instant hot water operation will end before the fluid in the circulation path is sufficiently heated. Conversely, if a margin is added to set the end judgment value in order to avoid such a case, the instant hot water operation will continue even after the fluid in the entire circulation path has been heated, which may result in unnecessary energy consumption.

[0009] The present invention has been made to solve such problems, and its object is to provide a water heating device and a water heating system that can appropriately set the termination conditions for instant hot water operation. [Means for solving the problem]

[0010] In one aspect of the present invention, a water heater is provided. The water heater supplies hot water to a hot water supply destination and includes a heating mechanism for heating a fluid, an internal path, a flow detector, and a controller for controlling the circulation pump and the heating mechanism. During instant hot water operation, which is performed with the circulation pump operating when the temperature of the fluid drops while hot water supply to the hot water supply destination is stopped, the internal path, in combination with an external path formed between two ports of the water heater outside the water heater and not including the hot water supply destination, forms an instant hot water circulation path through which the fluid passes through the two ports and the heating mechanism. The flow detector is disposed within the instant hot water circulation path. When instant hot water operation is started, the controller operates the circulation pump at a constant output and the heating mechanism for a minimum drive time set based on the flow rate detected by the flow detector under conditions in which the circulation pump operates at a predetermined constant output and the instant hot water circulation path is formed.

[0011] In one aspect of the present invention, a hot water supply system is provided. The hot water supply system includes a hot water supply device including a heating mechanism for heating a fluid, a circulation pump, an instant hot water circulation path, a flow detector, and a controller for controlling the circulation pump and the heating mechanism. The circulation pump operates in instant hot water operation, which is performed in response to a drop in the temperature of the fluid while hot water supply to the hot water supply destination is stopped. The instant hot water circulation path includes an internal path and an external path when the circulation pump is operating. The internal path is formed between two ports of the hot water supply device so that the fluid passes through the heating mechanism inside the hot water supply device when the circulation pump is operating. The external path is formed outside the hot water supply device between the two ports so as not to include the hot water supply destination of the hot water supply device. The flow detector is provided within the instant hot water circulation path. When instant hot water operation is started, the controller operates the circulation pump at a constant output and activates the heating mechanism until a minimum drive time has elapsed that is set based on the flow rate detection value of the flow detector under conditions in which the circulation pump operates at a predetermined constant output and the instant hot water circulation path is formed. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a water heater and a water heater system that are capable of appropriately setting the termination conditions for instant hot water operation. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram illustrating the configuration of a hot water supply system including a hot water supply device according to an embodiment of the present invention. [Figure 2] 2 is a block diagram illustrating an example of the hardware configuration of a controller shown in FIG. 1. FIG. [Figure 3] 4 is a flowchart illustrating a control process for an instant hot water operation by the water heater according to the first embodiment. [Figure 4] FIG. 10 is a conceptual diagram illustrating the calculation process of the estimated path length of the instant hot water circulation path. [Figure 5] FIG. 10 is a conceptual diagram showing the relationship between the detected flow rate value and the required circulation time. [Figure 6] 10 is a flowchart illustrating a control process for an instant hot water operation by a water heater according to a second embodiment. [Figure 7] FIG. 4 is a state transition diagram illustrating intermittent heating control. [Figure 8] FIG. 10 is a block diagram illustrating another example of the configuration of the hot water supply device and the hot water supply system. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the following description, the same or corresponding parts in the drawings are designated by the same reference numerals, and their description will not be repeated in principle.

[0015] [Embodiment 1] FIG. 1 is a block diagram illustrating the configuration of a hot water supply system 1A including a hot water supply device according to this embodiment.

[0016] 1, hot water supply system 1A includes water heater 100, low-temperature water piping 110, high-temperature water piping 120, and circulation piping 130. Water heater 100 has water inlet port 11, hot water outlet port 12, and circulation port 13.

[0017] Low-temperature water is supplied to low-temperature water pipe 110. The low-temperature water is typically supplied from a water pipe (not shown). Low-temperature water pipe 110 is connected to water inlet port 11 of water heater 100. High-temperature water pipe 120 is connected between hot water outlet port 12 of water heater 100 and hot water tap 200. Circulation pipe 130 branches off from high-temperature water pipe 120 and is connected to circulation port 13 of water heater 100.

[0018] The water heater 100 includes a controller 10, a water inlet path 20, a check valve 21, a bypass path 22, a circulation path 23, a water outlet path 25, a combustion mechanism 30, a heat exchanger 40, a circulation pump 80, and a flow control valve 90.

[0019] The water inlet path 20 is formed between the water inlet port 11 and the input side (upstream side) of the heat exchanger 40 via a check valve 21. The combustion mechanism 30 is typically constituted by a burner that generates heat by burning gas, oil, or the like.

[0020] The heat exchanger 40 uses the heat generated by the combustion mechanism 30 to heat and increase the temperature of the low-temperature water (fluid) introduced through the water inlet path 20. The combustion mechanism 30 and the heat exchanger 40 constitute one embodiment of a "heating mechanism."

[0021] The hot water outlet path 25 is formed between the output side (downstream side) of the heat exchanger 40 and the hot water outlet port 12. The bypass path 22 connects the inlet path 20 and the hot water outlet path 25 without passing through the heat exchanger 40. By controlling the flow rate adjustment valve 90 with the controller 10, it is possible to adjust the ratio (bypass flow rate ratio) of the flow rate of the bypass path 22 to the total flow rate (the sum of the flow rate of the heat exchanger 40 and the flow rate of the bypass path 22).

[0022] In such a bypass configuration, a portion of the low-temperature water bypasses the heat exchanger 40 and remains unheated, and is mixed downstream of the heat exchanger 40, thereby supplying high-temperature water from the hot water outlet port 12. This makes it possible to increase the output temperature from the heat exchanger 40 (heating mechanism), which is advantageous in suppressing drainage generated when the exhaust gas from the combustion mechanism 30 is cooled on the surface of the heat exchanger 40.

[0023] Circulation path 23 is formed between circulation port 13 and water inlet path 20 (connection point 27). Circulation pump 80 is connected to circulation path 23. Alternatively, circulation pump 80 may be connected to circulation piping 130 outside water heating apparatus 100. The operation and stopping of circulation pump 80 is controlled by controller 10. In addition, a flow rate sensor 76 is arranged in circulation path 23. Flow rate sensor 76 can be arranged between circulation port 13 and circulation pump 80.

[0024] A flow rate sensor 75 that outputs a flow rate value of low-temperature water is arranged in the water inlet path 20. Flow rate detection values ​​Qf and Qcr by the flow rate sensors 75 and 76 are input to the controller 10. A temperature sensor 71 is also arranged in the water inlet path 20. The temperature sensor 71 detects the inlet water temperature Tw before heating by the heat exchanger 40.

[0025] Temperature sensors 72 and 73 are arranged in hot water outlet path 25. Temperature sensor 72 is arranged in hot water outlet path 25 downstream of connection point 26 with bypass path 22, and detects outlet hot water temperature Th. Meanwhile, temperature sensor 73 is arranged upstream of connection point 26, and detects boiler body temperature Tb, which corresponds to the output temperature from heat exchanger 40. The fluid temperatures detected by temperature sensors 71 to 73 are input to controller 10.

[0026] FIG. 2 is a block diagram illustrating an example of the hardware configuration of the controller 10. As shown in FIG. 2, the controller 10 is typically configured by a microcomputer. The controller 10 includes a CPU (Central Processing Unit) 15, a memory 16, an input / output (I / O) circuit 17, and an electronic circuit 18. The CPU 15, the memory 16, and the I / O circuit 17 can exchange signals with each other via a bus 14. The electronic circuit 18 is configured to execute predetermined arithmetic processing using dedicated hardware. The electronic circuit 18 can exchange signals with the CPU 15 and the I / O circuit 17.

[0027] CPU 15 receives output signals (detected values) from each sensor, including temperature sensors 71-73 and flow rate sensors 75, 76, via I / O circuit 17. Furthermore, CPU 15 receives signals indicating operation instructions input to remote controller 92 via I / O circuit 17. The operation instructions include, for example, an on / off operation of the operation switch of water heating apparatus 100, a hot water supply temperature setting, and various time reservation settings (also referred to as "timer settings"). CPU 15 generates operation commands for controlling each component device, including combustion mechanism 30 and circulation pump 80, so that water heating apparatus 100 operates in accordance with the operation instructions. It is also possible to output information to the user using a display screen and speaker (not shown) provided in remote controller 92.

[0028] Referring again to FIG. 1, the operation of water heating apparatus 100 will be described. During hot water operation when hot water tap 200 is open, the supply pressure of low-temperature water introduces low-temperature water into water inlet path 20. When the operation switch of water heater 100 is on, and flow rate sensor 75 detects a flow rate exceeding the minimum operating flow rate (MOQ), controller 10 activates combustion mechanism 30.

[0029] As a result, the high-temperature water heated by the combustion mechanism 30 and the heat exchanger 40 is mixed with the low-temperature water passing through the bypass path 22, and then is output from the high-temperature water pipe 120 to the hot water tap 200 via the hot water outlet port 12. The hot water tap 200 is shown as a representative example of a "hot water supply destination" of the hot water supply device 100. The hot water supply destination may include a solenoid valve that turns on and off the hot water supply to a bathtub or the like, and is not limited to a valve that is directly opened and closed by a user.

[0030] During normal hot water supply operation, controller 10 stops circulation pump 80 and controls the fluid temperature (outlet hot water temperature Th) detected by temperature sensor 72 to the hot water supply set temperature Tr input to remote controller 92. Specifically, outlet hot water temperature control can be performed by combining control of the amount of heat (amount of heat generated) by combustion mechanism 30 (heating mechanism) with control of the bypass flow rate ratio by flow adjustment valve 90.

[0031] For example, the amount of heat Pset (per unit time) to be generated by the combustion mechanism 30 can be set according to the following formula (1): where k is a conversion coefficient to the amount of heat. Pset = k × Qf × (Tr-Tw) … (1)

[0032] The bypass flow rate ratio set by the flow rate adjustment valve 90 can be adjusted by feedback control based on the deviation between the hot water outlet temperature Th and the hot water supply set temperature Tr.

[0033] When hot water supply operation is stopped, the temperature of the fluid remaining in the hot water outlet path 25 and the high-temperature water pipe 120 drops, and there is a concern that it may take some time to supply hot water at an appropriate temperature to the hot water tap 200 after the next hot water supply operation is started. For this reason, the hot water supply device 100 is provided with an instant hot water operation function to quickly supply high-temperature water after the hot water supply operation is started. Instant hot water operation is achieved by operating the circulation pump 80 to form an instant hot water circulation path including the heat exchanger 40 (heating mechanism) while hot water supply to the hot water supply destination is stopped due to the closure of the hot water tap 200, etc.

[0034] The instant hot water circulation path is formed by a loop that runs from circulation port 13 via circulation path 23, water inlet path 20 (downstream of connection point 27), heat exchanger 40, hot water outlet path 25, hot water outlet port 12, high-temperature water piping 120 (upstream of connection point 125), and circulation piping 130, returning to circulation port 13. Of the loop, the portion inside water heater 100 corresponds to an example of an "internal path," and the portion outside water heater 100, including circulation piping 130, corresponds to an example of an "external path." Also, in the example of Figure 1, hot water outlet port 12 and circulation port 13 correspond to an example of "two ports" through which the fluid in the instant hot water circulation path passes.

[0035] When the instant hot water circulation path is formed by the operation of the circulation pump 80, the flow rate detection value Qf of the flow rate sensor 75 exceeds the MOQ, and the combustion mechanism 30 is activated. This heats the hot water in the instant hot water circulation path.

[0036] In the configuration of Figure 1, it can be seen that temperature sensors 71-73 and flow sensors 75, 76 are arranged in the instant hot water circulation path. Therefore, flow sensors 75, 76 correspond to an embodiment of a "flow detector." Temperature sensors 71-73 correspond to an embodiment of a "temperature detector," but an embodiment will be described in which temperature sensor 72 is the "temperature detector." Furthermore, during instant hot water operation, the flow rates detected by flow sensors 75 and 76 are the same, but in this specification, an embodiment will be described in which flow sensor 75 is the "flow detector."

[0037] If the hot water tap 200 is opened during instant hot water operation, the instant hot water operation is stopped and hot water supply operation is started with the circulation pump 80 stopped. When the hot water tap 200 is opened, the flow rate detection value Qf by the flow rate sensor 75 (water inlet path 20) increases relative to the flow rate detection value Qcr by the flow rate sensor 76 (circulation path 23). Therefore, during instant hot water operation, the controller 10 can monitor whether the hot water tap 200 is closed or open by comparing the difference (Qf-Qcr) between the flow rate detection values ​​Qf and Qcr with a predetermined judgment value.

[0038] FIG. 3 shows a flowchart for explaining the control process of the instant hot water operation by the hot water supply device according to Embodiment 1. The control process shown in FIG. 3 is repeatedly activated by the controller 10 when the hot water supply operation is stopped.

[0039] Referring to FIG. 3, in step (hereinafter simply referred to as "S") 110, the controller 10 determines the start condition of the instant hot water operation. S110 includes S111 to S114.

[0040] In S111, it is determined whether the instant hot water operation mode is on. The instant hot water operation mode is turned on and off, for example, according to the user's switch operation. Alternatively, the on period of the instant hot water operation mode may be provided by the user's timer setting or learning of past history. S111 is determined as YES when the instant hot water operation mode is on, while it is determined as NO when it is off.

[0041] In S112, it is determined whether the hot water supply is stopped by comparing the flow rate detection value Qf with the MOQ. When Qf < MOQ due to the closing of the hot water tap 200 or the like, S112 is determined as YES and it is determined that the hot water supply is stopped. On the contrary, when hot water or water is output from the hot water supply device 100 and the flow rate detection value Qf ≧ MOQ, S112 is determined as NO.

[0042] In S113, the detected value of the fluid temperature in the instant hot water circulation path, for example, the hot water outlet temperature Th detected by the temperature sensor 72, is compared with the determination temperature T1. The determination temperature T1 is set to be α [°C] lower than the hot water supply set temperature Tr (T1 = Tr - α). For example, α can be set to about 10 [°C]. S113 is determined as YES if Th < T1, while it is determined as NO when Th ≧ T1. The determination temperature T1 corresponds to the "first determination temperature".

[0043] In S114, the interval time Tint between instant hot water operations, i.e., the time elapsed since the end of the previous instant hot water operation, is compared with the judgment time Trst. Trst can be set to, for example, about 10 minutes. In S114, if Tint > Trst, the judgment is YES, but if Tint ≦ Trst, the judgment is NO.

[0044] When all of S111 to S114 are judged as YES, the controller 10 judges as YES in S110 and starts the instant hot water operation. On the other hand, when any of S111 to S114 is judged as NO, the controller 10 judges as NO in S110 and does not start the instant hot water operation.

[0045] When the instant hot water operation is started, the controller 10 starts the circulation pump 80 in S120. The output (driving torque) of the circulation pump 80 is set to a predetermined constant value. Furthermore, in S130, a timer is started to measure the operation time Tm of the circulation pump 80. When the instant hot water circulation path is formed by the operation of the circulation pump 80, the controller 10 activates the heating mechanism in response to the flow rate detection value Qf exceeding the MOQ (S140). For example, the burner combustion is turned on to start heating.

[0046] After circulating pump 80 is operated, controller 10 executes S150 to calculate the time required for the fluid to circulate once through the instant hot water circulation path of water heater 100 (required circulation time Tcr) under the condition that circulating pump 80 is operating at a predetermined constant output, based on flow rate detection value Qf by flow rate sensor 75. S150 includes S152, S154, and S156.

[0047] It is not necessary to execute S150 each time the instant hot water operation starts, and once the required circulation time Tcr is obtained by S150, execution of S150 can be omitted thereafter. Alternatively, S150 can be executed again in conjunction with the start of the instant hot water operation after a certain period of time has elapsed or after a certain number of instant hot water operations have been performed.

[0048] In S152, the controller 10 determines whether the flow rate detection value Qf has stabilized while the circulation pump 80 is operating at a constant output. For example, if the difference between the maximum and minimum values ​​of the flow rate detection value Qf within a certain period of time becomes equal to or less than a predetermined value, the determination in S152 is YES.

[0049] When flow rate detection value Qf becomes stable (YES in S152), controller 10 calculates, in S154, from flow rate detection value Qf, estimated path length Lx of the instant hot water circulation path of water heating apparatus 100. Furthermore, in S156, required circulation time Tcr is calculated from estimated path length Lx calculated in S154.

[0050] Here, the calculation of the estimated value of the instant hot water circulation path length and the time required for one circulation in S150 will be described in detail with reference to Figs.

[0051] If the diameter of the pipes that make up the hot water instantaneous circulation path is uniform, and the output (driving torque) of the circulation pump 80 is constant, the pressure loss due to the pipes is proportional to the pipe length.

[0052] Therefore, as shown in Figure 4, two flow rate detection values ​​are stored in advance when the circulation pump 80 is operated at a predetermined output torque TR1 [N·m] in a circulation path with a specified pipe diameter a [m] and a known total pipe length (i.e., path length).

[0053] Specifically, data indicating a flow rate value Q1 [L / min] in a circulation path with a path length L1 [m] and a flow rate value Q2 [L / min] in a circulation path with a path length L2 [m] is stored in advance in the controller 10. The flow rate values ​​Q1 and Q2 can be determined in advance by an actual machine experiment using circulation paths designed with the same piping diameter, and data indicating the experimental results can be written into the controller 10 at the time of shipping from the factory.

[0054] In S154, estimated path length Lx of the instant hot water circulation path in water heating apparatus 100 can be calculated by linear interpolation using flow rate detection value Qf after stabilization in S152 for (L1, Q1) and (L2, Q2) in Figure 4. For example, according to Figure 4, estimated path length Lx can be calculated from Q1, Q2, L1, and L2 using the following equation (2). Lx=L1+(Qf-Q1)·(L1-L2) / (Q1-Q2) …(2)

[0055] If equation (2) is divided into a term with Qf as a variable and a constant term that does not depend on Qf, it can be expressed as equation (3). Lx=A·Qf+B …(3) A=(L1-L2) / (Q1-Q2) B=L1-Q1·(L1-L2) / (Q1-Q2)

[0056] The volume of fluid passing through the hot water circulation path is V=(π·a 2 / 4)·Lx, so the time required for the fluid to circulate around the hot water circulation path at a flow rate detection value Qf can be calculated as V / Qf.

[0057] Therefore, as shown in Figure 5, the circulation time required Tcr is inversely proportional to the flow rate detection value Qf [L / min], and specifically, it can be calculated by substituting Qf [L / min] into the following equation (4) using A and B in equation (3).

[0058] Tcr=(π·a 2 / 4)·Lx[L / min] / (Qf·0.001[m 3 / L]) =250π·a 2 (B / Qf+A) …(4)

[0059] Again, referring to FIG. 3, the controller 10 sets, by S160, the minimum drive time Tmin, which is the end determination value related to the operation time Tm of the circulation pump 80, according to the circulation required time Tcr calculated in S150. During the instant hot water operation, the controller 10 compares, by S170, the operation time Tm measured by the timer with the minimum drive time Tmin set in S160.

[0060] Until the operation time Tm reaches the minimum drive time Tmin (when the NO determination is made in S170), the operation of the circulation pump 80 is maintained by S180, and the instant hot water operation is continued. On the other hand, when the operation time Tm reaches the minimum drive time Tmin (when the YES determination is made in S170), the circulation pump 80 is stopped by S190. Accordingly, when the flow rate detection value Qf drops below the MOQ, the combustion mechanism 30 is also stopped. Thereby, the instant hot water operation ends.

[0061] The minimum drive time Tmin can be set, for example, to be equal to the circulation required time Tcr. By doing so, the fluid in substantially the entire instant hot water circulation path can be heated without wasting heating energy. Alternatively, if the minimum drive time Tmin is set in the region where Tmin < Tcr based on the circulation required time Tcr, the eco-mode instant hot water operation similar to that in Patent Document 1 can be realized.

[0062] During the instant hot water operation, the controller 10 monitors the hot water faucet 200 based on (Qf - Qcr) in parallel with the above-described processes of S120 to S190. When the opening (start of hot water supply) of the hot water faucet 200 is detected due to an increase in (Qf - Qcr), the process proceeds to S190 by interrupt processing, and the instant hot water operation ends.

[0063] As described above, according to the hot water supply device according to Embodiment 1, by estimating the time required for the fluid in the instant hot water circulation path formed by the operation of the circulation pump 80 to make one round from the flow rate detection value, the end condition of the instant hot water operation can be appropriately set without performing the instant hot water operation during the test operation.

[0064] 3, two known flow rates (Q1, Q2) for the circulation pump 80 under the same conditions for a pipe with the same diameter as the instantaneous hot water circulation path and two known path lengths (L1, L2) are stored in advance. From the relationship between the detected flow rate Qf and the flow rates Q1, Q2, linear interpolation for the path lengths L1, L2 is performed. However, the calculation of the estimated path length Lx is not limited to this example. For example, a lookup table or a formula for directly calculating the estimated path length Lx from the detected flow rate Qf (S152) when the circulation pump 80 is operated at an output torque TR1 [N m] for an instantaneous hot water circulation path with the same diameter as the instantaneous hot water circulation path can be created in advance based on actual experimental results, and the lookup table or formula can be used to calculate the estimated path length Lx in S150. In the configuration example of FIG. 1, it is also possible to calculate the estimated path length Lx and the required circulation time Tcr using the flow rate detection value Qcr of the flow rate sensor 76.

[0065] [Embodiment 2] As explained in the first embodiment, when the hot water circulation path is long, the flow rate during hot water operation decreases due to the influence of pressure loss. In contrast, the heating mechanism has a minimum amount of heat that can be generated stably. For example, in the burner that constitutes the combustion mechanism 30, there is a certain lower limit to the amount of fuel combustion that can maintain stable combustion, and the amount of heat generated by the fluid during fuel combustion at this lower limit corresponds to the minimum amount of heat mentioned above.

[0066] In such a case, it may be difficult to continuously heat the fluid during instant hot water operation under low flow rates. In the second embodiment, we will explain a control method that combines intermittent heating to deal with such cases.

[0067] Fig. 6 shows a flowchart illustrating the control process for instant hot water operation by the hot water supply device according to embodiment 2. The control process shown in Fig. 6 is also started by controller 10 when instant hot water operation is stopped.

[0068] Referring to Figure 6, the controller 10 determines whether the conditions for starting the instant hot water operation are met by S110, which is the same as in Figure 3, and when the conditions for starting are met (YES in S110), it starts the circulation pump 80 by S120 and S130, which are the same as in Figure 3, and starts a timer for measuring the operating time Tm of the circulation pump 80. Furthermore, in the second embodiment, a flag Ft is introduced that indicates the temperature rise history during the instant hot water operation. When the instant hot water operation starts, for example, the flag Ft is initialized to 0 by S130.

[0069] As in Fig. 3, controller 10 activates the heating mechanism in response to the detected flow rate Qf of the instant hot water circulation path exceeding the MOQ in response to the operation of circulation pump 80 (S140). Furthermore, if necessary, S150, similar to Fig. 3, is executed to calculate the required circulation time Tcr of the instant hot water circulation path of water heater 100. At the start of instant hot water operation, S160, similar to Fig. 3, sets the minimum drive time Tmin, similar to the first embodiment.

[0070] The controller 10 continues the instant hot water operation by applying the intermittent heating control according to S200 and maintaining the operation of the circulation pump 80 (S180) until the operating time Tm reaches the minimum drive time Tmin (when the result of S170 is NO).

[0071] FIG. 7 shows a state transition diagram illustrating the intermittent heating control in S200. 7, in the intermittent heating control, at the start of the instant hot water operation, the flag Ft is initially set to 0, and when the flow rate detection value Qf exceeds the MOQ, combustion by the combustion mechanism 30 is turned on. That is, the heating mechanism enters the "heating" state.

[0072] When combustion is on, if the detected value of the fluid temperature in the instant hot water circulation path, for example, the temperature detected value (hot water outlet temperature Th) by the temperature sensor 72, rises above the determination temperature T2 (T2>T1) set higher than the determination temperature T1, after setting the flag Ft = 1, the combustion by the combustion mechanism 30 is turned off, and the heating mechanism enters the "heating stopped" state. For example, the determination temperature T2 can be set higher than the hot water supply set temperature Tr. If T2 = Tr+β, β can be set to about 3[°C]. However, β<0, and the determination temperature T2 may be set lower than the hot water supply set temperature Tr. The determination temperature T2 corresponds to the "second determination temperature".

[0073] For example, when the amount of heat to be generated from the combustion mechanism 30 set according to Equation (1) based on the incoming water temperature Tw and the flow rate detected value Qf is smaller than the minimum amount of heat of the above-described combustion mechanism 30, by continuing heating at the minimum amount of heat, a case where Th>T2 will occur.

[0074] On the other hand, after the transition from combustion on to combustion off, if the detected value of the fluid temperature in the instant hot water circulation path, for example, the temperature detected value (hot water outlet temperature Th) by the temperature sensor 72, drops below the determination temperature T3 (T3<T2) set lower than the determination temperature T2, combustion is turned on again, that is, the combustion mechanism 30 is operated. At this time, the flag Ft is maintained at "1". That is, the flag Ft is initialized to "0" at the start of the instant hot water operation when Th<T1 (T1 = Tr-α), and once the temperature rise until Th>T2 (T2 = Tr+β) occurs, it is maintained at "1" until the end of the instant hot water operation.

[0075] For example, the determination temperature T3 can be set lower than the hot water supply set temperature Tr and higher than the determination temperature T1 at the start condition of the instant hot water operation. However, the determination temperature T3 may be set to be equal to or higher than the hot water supply set temperature Tr, or may be set to be equal to or lower than the determination temperature T1. The determination temperature T3 corresponds to the "third determination temperature".

[0076] In this way, by applying intermittent heating control by turning the combustion mechanism 30 on and off in response to the rise and fall of the detected fluid temperature in the instant hot water circulation path (for example, the outlet hot water temperature Th), instant hot water operation can be continued until the operating time Tm reaches the minimum driving time Tmin without excessively increasing the fluid temperature, even if the amount of heat to be generated from the combustion mechanism 30 is less than the minimum amount of heat.

[0077] During intermittent heating control, if the flow rate detection value Qf falls below the MOQ due to the cessation of circulation pump 80 due to the end of instant hot water operation, intermittent heating control is terminated. In this case, even if the detected value of the fluid temperature in the instant hot water circulation path falls, a transition from combustion off (heating stopped) to combustion on (heating resumed) does not occur.

[0078] 6, when the operating time Tm reaches the minimum drive time Tmin (YES in S170), the controller 10 determines the value of the flag Ft introduced in the intermittent heating control in S210. If Ft=1, that is, if there is a history of the detected fluid temperature in the instant hot water circulation path (e.g., the outlet hot water temperature Th) rising to the determination temperature T2 during the current intermittent heating (YES in S210), the process proceeds to S190, where the circulation pump 80 is stopped to end the instant hot water operation.

[0079] In contrast, when flag Ft = 0 (NO determination in S210), the combination of a YES determination in S170 and a NO determination in S210 causes the operation of circulation pump 80 to continue (S180). In this case, with intermittent heating control (Figure 7), the operation of circulation pump 80 continues (S180) until a history of the outlet hot water temperature Th rising to the determination temperature T2 occurs. Then, when Th > T2, the combination of a YES determination in S170 and a YES determination in S210 causes the process to proceed to S190, and the instant hot water operation is terminated. Also in FIG. 6, during instant hot water operation, when an increase in (Qf-Qcr) detects that the hot water tap 200 has been opened (start of hot water supply), an interrupt process advances the process to S190, and instant hot water operation is ended.

[0080] In this way, according to the water heater of embodiment 2, by combining intermittent heating control, instant hot water operation that follows the same termination conditions as embodiment 1 can be smoothly performed even at low flow rates.

[0081] Next, modifications of the hot water supply and the hot water supply system according to this embodiment will be further described. FIG. 8 shows a block diagram illustrating a modified configuration of a hot water supply device and a hot water supply system according to a modified example of the present embodiment.

[0082] 8, hot water supply system 1B includes water heating device 100X, low-temperature water piping 110, high-temperature water piping 120, circulation piping 130, and circulation pump 80. Water heating device 100X does not include circulation port 13, but has water inlet port 11 and hot water outlet port 12. Therefore, unlike water heating device 100 in FIG. 1, water heating device 100X does not include circulation path 23 and flow rate sensor 76 inside.

[0083] Low-temperature water piping 110, which receives a supply of low-temperature water, is connected to water inlet port 11 of water heater 100X and also to circulation piping 130. That is, in water heater system 1B, circulation piping 130 is connected between low-temperature water piping 110 and high-temperature water piping 120.

[0084] Circulation pump 80 is, for example, connected by an interposition to circulation piping 130. Circulation pump 80 may be disposed outside water heating apparatus 100X as illustrated in Fig. 8, or may be connected by an interposition to water inlet path 20 inside water heating apparatus 100X.

[0085] During hot water supply operation, circulation pump 80 is stopped, so that a fluid path similar to that of water heating apparatus 100 in Fig. 1 can be formed inside water heating apparatus 100X. Therefore, water heating apparatus 100X can also perform hot water supply operation similar to that of water heating apparatus 100 (Fig. 1).

[0086] On the other hand, by operating the circulation pump 80 with the flow rate adjustment valve 90 closed (flow rate = 0), an instant hot water circulation path including the heat exchanger 40 (heating mechanism) can also be formed in the water heater 100X.

[0087] Specifically, an instant hot water circulation path can be configured by a loop that runs from water inlet port 11 through water inlet path 20, heat exchanger 40, hot water outlet path 25, hot water outlet port 12, high-temperature water piping 120 (upstream of connection point 125), circulation piping 130, and low-temperature water piping 110 (downstream of connection point 127), returning to water inlet port 11. In the configuration of FIG. 8, the portion of the loop that is internal to water heater 100X corresponds to an example of an "internal path," and the portion external to water heater 100X, including circulation piping 130, corresponds to an example of an "external path." In the example of FIG. 8, water inlet port 11 and hot water outlet port 12 correspond to an example of "two ports" through which fluid in the instant hot water circulation path passes.

[0088] In water heating device 100X, flow sensor 75 and temperature sensors 71 to 73 are arranged in the instant hot water circulation path, as in water heating device 100, so it is possible to perform instant hot water operation applying embodiment 1 or 2 using the flow rate detection value Qf of the instant hot water circulation path. 8, the controller 10 can monitor whether the hot water tap 200 is closed or open during instant hot water operation based on the behavior of the flow rate detection value Qf. That is, when the flow rate detection value Qf increases beyond a predetermined judgment value while the circulation pump 80 is operating at a constant output, the controller 10 can detect that the hot water tap 200 has been opened (start of hot water supply) and end the instant hot water operation.

[0089] In addition, in this embodiment, the heat source in the heating mechanism is not limited to the combustion mechanism 30 that heats by burning fuel, and any heat source can be applied.

[0090] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0091] 1A, 1B hot water supply system, 10 controller, 11 water inlet port, 12 hot water outlet port, 13 circulation port, 14 bus, 15 CPU, 16 memory, 17 I / O circuit, 18 electronic circuit, 20 water inlet path, 21 check valve, 22 bypass path, 23 circulation path, 25 hot water outlet path, 26, 27, 125, 127 connection point, 30 heating mechanism, 40 heat exchanger, 71 to 73 temperature sensors, 75, 76 flow rate sensors, 80 circulation pump, 90 flow rate adjustment valve, 92 remote controller, 100, 100X hot water supply device, 110 low-temperature water piping, 120 high-temperature water piping, 130 circulation piping, 200 hot water tap, Ft flag (instant hot water operation temperature rise history), L1, L2 path length (known), Lx path length estimate, Q1, Q2 Flow rate value (known), Qf detected flow rate value, T1 to T3 judgment temperatures, Tb boiler body temperature, Tcr required circulation time, Th outlet hot water temperature, Tint interval time, Tm operating time (circulation pump), Tmin minimum operating time, Tr hot water setting temperature, Trst judgment time (interval time), Tw inlet water temperature.

Claims

1. A hot water supply device for supplying hot water to a hot water supply destination, a heating mechanism for heating the fluid; In an instant hot water operation that is performed with the operation of a circulation pump when the temperature of the fluid drops while hot water supply to the hot water supply destination is stopped, an internal path that, together with an external path formed between two ports of the hot water supply device outside the hot water supply device, forms an instant hot water circulation path through which the fluid passes through the two ports and the heating mechanism; A flow rate detector disposed in the hot water circulation path; a controller that controls the circulation pump and the heating mechanism; The hot water supply destination is connected to the external path via a pipe, The controller When the instant hot water operation is started, the circulation pump is operated at a predetermined constant output and the heating mechanism is operated until a minimum operating time set based on the flow rate detection value of the flow rate detector under conditions in which the circulation pump operates at the predetermined constant output and the instant hot water circulation path is formed has elapsed.

2. Further, a temperature detector is provided in the hot water circulation path. The instant hot water operation is started when the temperature detected by the temperature detector falls below a first determination temperature set lower than the hot water supply setting temperature to the hot water supply destination during the hot water supply stop, The hot water supply device of claim 1, wherein the controller stops heating by the heating mechanism when the detected temperature rises above a second judgment temperature set higher than the first judgment temperature during heating by the heating mechanism while the circulation pump is operating.

3. The hot water supply device of claim 2, wherein the controller controls the heating mechanism so that heating by the heating mechanism resumes when the detected temperature drops below a third judgment temperature set lower than the second judgment temperature while heating by the heating mechanism is stopped while the circulation pump is operating.

4. The hot water supply device described in claim 2 or 3, wherein when the minimum operating time has elapsed since the start of the instant hot water operation, if there is no history of the detected temperature by the temperature detector rising to the second judgment temperature during the instant hot water operation, the controller continues to operate the circulation pump and the heating mechanism until the detected temperature rises to the second judgment temperature.

5. The controller stores in advance a first flow rate value and a second flow rate value in a first instantaneous hot water circulation path of a first path length and a second instantaneous hot water circulation path of a second path length, the first flow rate value and the second flow rate value being the same diameter as the instantaneous hot water circulation path and formed by operating the circulation pump at the constant output, in correspondence with the first path length and the second path length, The controller calculates an estimated path length of the instant hot water circulation path of the water heating device based on the first path length and the second path length from the relationship between the flow rate detection value of the flow rate detector under conditions in which the circulation pump operates at the constant output and the first flow rate value and the second flow rate value, and calculates the circulation time required for the fluid to circulate around the instant hot water circulation path under the conditions from the estimated path length value, and sets the minimum operating time according to the calculated circulation time.

6. a water heater including a heating mechanism for heating a fluid; A circulation pump that is operated during an instant hot water operation performed in response to a temperature drop of the fluid while hot water supply to the hot water supply destination of the hot water supply device is stopped; an internal path formed between two ports of the water heater so that the fluid passes through the heating mechanism inside the water heater when the circulation pump is operated; and an external path formed between the two ports outside the water heater; A flow rate detector provided in the hot water circulation path; a controller that controls the circulation pump and the heating mechanism; The hot water supply destination is connected to the external path via a pipe, The controller When the instant hot water operation is started, the circulation pump is operated at a predetermined constant output and the heating mechanism is operated until a minimum operating time set based on the flow rate detection value of the flow rate detector under conditions in which the circulation pump operates at the predetermined constant output and the instant hot water circulation path is formed has elapsed.

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