Hot water supply device

Abstract

To provide a hot water supply device improved in accuracy in a heat-retention interval time.SOLUTION: Processing executed by a processor of a hot water supply device includes: a step (S335) of starting measurement of a heat-retention interval time ti; a step (S350) of acquiring a bath return temperature (Tcx) as a temperature of hot water in a bathtub on the basis of an output of a temperature sensor when the heat-retention interval time ti has passed from the start of the measurement (YES in step S340); a step (S360) of calculating the heat-retention interval time ti by using a formula (ti={Δt / (Ts-Tcx)}×ti (previous value)) in a case when the bath return temperature (Tcx) is a bath set temperature (Ts) or less (YES in step S355); and a step (S390) of executing a heat-retention reheating operation.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to control of a water heating apparatus, and more particularly to control of a water heating apparatus having a heat retention function. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in a bath hot water supply system having a bath heat retention function, there is known a bath heat retention device that can estimate the interval time required for the heat retention operation and perform heat retention at an appropriate time interval (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-189696 [Patent Document 2] Japanese Patent Application Publication No. 11-159873 [Patent Document 3] Japanese Patent Application Publication No. 11-193956 Summary of the Invention [Problem to be solved by the invention]

[0004] Regarding the bath insulation function, the duration of insulation (insulation interval) is calculated using the amount of change in water temperature during post-purge immediately after reheating operation. Therefore, immediately after combustion, there is almost no difference between the bath set temperature and the temperature detected by the sensor. Also, because the amount of change in water temperature is small, the detected temperature is easily affected by sensor variation. As a result, the calculation accuracy of the insulation interval can be low. Therefore, technology is needed to improve the accuracy of the insulation interval.

[0005] The present disclosure has been made in view of the above-described background, and one of the objects according to a certain aspect is to provide a technique for improving the accuracy of a warming interval time. [Means for solving the problem]

[0006] A water heater according to an embodiment includes a combustion unit that heats water and supplies the hot water to a bathtub, a circulation pump that sends the hot water in the bathtub to the combustion unit, and a control device for controlling the operation of the water heater. The operations include a filling operation that supplies hot water at a predetermined temperature to the bathtub, and a heat-retention operation that operates the combustion unit and the circulation pump so that the temperature of the hot water in the bathtub rises to a predetermined set temperature every time a predetermined interval is set as a heat-retention interval until a heat-retention operation is started after the filling operation is completed. The control device acquires the temperature of the hot water in the bathtub before the heat-retention operation, calculates the amount of change in the temperature of the hot water in the bathtub based on the acquired temperature of the hot water and the set temperature, and calculates the heat-retention interval until the start of the next heat-retention operation based on the amount of change, a predetermined reference water temperature change, and a heat-retention interval.

[0007] In another aspect, the calculation of the heat retention interval time is performed every time a heat retention operation is started.

[0008] According to another aspect, the water heating apparatus further includes a memory for storing the calculated heat retention interval. Calculating the heat retention interval until the start of the next heat retention operation includes calculating the heat retention interval using the heat retention interval stored in the memory after the completion of the water filling operation that is performed after the next heat retention operation.

[0009] According to yet another aspect, the operation of the hot water supply apparatus further includes a re-heating operation. Calculating a heat-retention interval time until a next heat-retention operation is started includes calculating a new heat-retention interval time based on the fact that the re-heating operation has been performed during execution of the heat-retention operation.

[0010] According to certain embodiments, the accuracy of the warming interval time may be improved. The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of an outline of the configuration of a hot water supply system 100. FIG. [Diagram 2] FIG. 2 is a block diagram illustrating a configuration of a controller 12 according to an embodiment. [Diagram 3] 4 is a flowchart showing a part of the processing executed by the controller 12. [Figure 4] 2 is a diagram showing an example of a screen displayed on a display unit 31 of a remote control 30. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0013] The configuration of a hot water supply system 100 according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram illustrating an example of an outline of the configuration of hot water supply system 100. Hot water supply system 100 includes a hot water supply device 110. In addition to a hot water tap (not shown) and the like, hot water supply device 110 includes a bathtub 20 installed in a bathroom 200 as a hot water supply destination.

[0014] The water heating device 110 comprises a housing 1, a burner 2, a fan 3, a heat exchanger 4, a water inlet pipe 5, a hot water supply pipe 6, a bypass valve 7, a bypass pipe 7a, a circulation path 8, temperature sensors 9, 12T, 18, 19, a circulation pump 10, a water level sensor 11, a controller 12, a bath hot water supply valve 13, electrical wiring 14, and remote controls 30, 50.

[0015] The housing 1 is provided so that the inside and outside of the housing 1 are in communication with each other, and has an exhaust port 1a for discharging combustion gas. The housing 1 is configured to be able to accommodate a burner 2, a fan 3, a heat exchanger 4, a water inlet pipe 5, a hot water supply pipe 6, a bypass valve 7, a bypass pipe 7a, temperature sensors 9, 12T, 18, 19, a circulation pump 10, a water level sensor 11, a controller 12, and a bath hot water supply valve 13. The housing 1 also accommodates a part of a circulation path 8 for reheating operation.

[0016] The burner 2 is configured to perform combustion operation by receiving a supply of fuel gas from a fuel supply system (not shown). The burner 2 supplies the combustion gas to the heat exchanger 4. The burner 2 has a burner 2a for hot water supply and a burner 2b for reheating.

[0017] Fan 3 supplies air for combustion to burner 2. Fan 3 has fan 3a that supplies air for combustion to burner 2a, and fan 3b that supplies air for combustion to burner 2b. Each of fans 3a and 3b has a blade and a motor for rotating the blade. When a current is supplied to the motor, the blade rotates, and fans 3a and 3b supply air for combustion. Fans 3a and 3b are disposed below burners 2a and 2b, respectively, in the height direction of water heater 110. Note that, regarding fan 3, FIG. 1 illustrates a configuration in which burners 2a and 2b each have one fan 3a and one fan 3b, respectively, but is not limited to the configuration illustrated in FIG. 1. In another aspect, a configuration in which one fan is shared by multiple burners 2a and 2b may be adopted.

[0018] Heat exchanger 4 has heat exchanger 4a for hot water supply and heat exchanger 4b for reheating. Heat exchangers 4a and 4b are respectively arranged above burners 2a and 2b in the height direction of hot water supply device 110. Heat exchangers 4a and 4b are arranged near exhaust port 1a.

[0019] The heat exchanger 4a recovers heat from the combustion gas supplied by the burner 2a. The heat exchanger 4b recovers heat from the combustion gas supplied by the burner 2b. Each of the heat exchangers 4a and 4b may include a primary heat exchanger that heats incoming water by heat exchange with the sensible heat (combustion heat) of the combustion gas of the burner 2, and a secondary heat exchanger that heats the flowing water by heat exchange with the latent heat of the combustion exhaust gas from the burner 2.

[0020] The water inlet pipe 5 is connected to a water supply pipe at the water inlet port 5a. When the hot water tap is turned on and / or the bath hot water valve 13 is opened, low-temperature water is introduced from the water inlet port 5a to the hot water supply device 110 by the supply pressure of the tap water. A temperature sensor 18 provided on the water inlet pipe 5 detects the temperature Tw of the water introduced from the water inlet port 5a.

[0021] The water inlet pipe 5 is branched into a boiler body pipe 5b and a bypass pipe 7a via a bypass valve 7. The boiler body pipe 5b is connected to one end of the heat exchanger 4a. The flow rate ratio of the bypass pipe 7a and the boiler body pipe 5b to the total flow rate of the water inlet pipe 5 is controlled by the opening degree of the bypass valve 7.

[0022] The other end of the heat exchanger 4a is connected to one end of the hot water supply pipe 6. Low-temperature water supplied from the water inlet pipe 5 to the boiler body pipe 5b is heated to a predetermined temperature by the heat exchanger 4a and output to the hot water supply pipe 6. A flow rate sensor 15 is disposed in the boiler body pipe 5b. The flow rate sensor 15 detects the flow rate of the heat exchanger 4a (boiler body flow rate).

[0023] On the other hand, the bypass pipe 7a is connected to the hot water supply pipe 6, bypassing the heat exchanger 4a. Therefore, the low-temperature water supplied from the water inlet pipe 5 to the bypass pipe 7a is output to the hot water supply pipe 6 without being heated by the heat exchanger 4a. In this way, the hot water supply device 110 can mix the high-temperature water output from the heat exchanger 4a and the low-temperature water that has passed through the bypass pipe 7a, and output hot water at an appropriate temperature according to the set temperature from the hot water supply pipe 6.

[0024] The other end of the hot water supply pipe 6 is connected to a hot water outlet 6a that is connected to a hot water tap (not shown) or the like. Therefore, when the hot water tap is opened, hot water at an appropriate temperature controlled to a set temperature is supplied from the hot water supply device 110 to the hot water tap via the hot water outlet 6a.

[0025] The hot water supply pipe 6 is further connected to a hot water supply pipe 13a leading to a bathtub 20. A bath hot water supply valve 13 is provided in the hot water supply pipe 13a. The bath hot water supply valve 13 may be configured, for example, by a solenoid valve that can be controlled to open and close. When the bath hot water supply valve 13 is opened, a path is formed for outputting hot water from the hot water supply pipe 6 to the hot water supply pipe 13a. As a result, the hot water supply device 110 can include the bathtub 20 as a hot water supply destination in addition to a hot water tap, etc.

[0026] In this specification, the supply of hot water from the water heater 110 to the bathtub 20 is referred to as "pouring hot water". This is to be distinguished from the supply of hot water to the outlet 6a (hot water tap, etc.). A flow rate sensor 16 is provided in the hot water supply pipe 13a. The flow rate sensor 16 detects the flow rate of hot water supplied from the water heater 110 to the bathtub 20. In this embodiment, the action of supplying hot water or water to the bathtub 20 via the hot water supply pipe 13a by opening the bath hot water supply valve 13, regardless of the hot water outlet temperature at the hot water supply pipe 6, is referred to as "pouring hot water". The hot water supply circuit can be composed of the burner 2a, fan 3a, heat exchanger 4a, water inlet pipe 5, boiler body pipe 5b, hot water supply pipe 6, bypass valve 7, bypass pipe 7a, and bath hot water supply valve 13, all of which are included in the water heater 110.

[0027] The circulation path 8 is a flow path that circulates hot water 21 in the bathtub 20 (hereinafter also referred to as bathtub water 21) within the water heater 110. The circulation path 8 has a return pipe 8a, a forward pipe 8b, and a circulation pump 10. One end of the return pipe 8a is connected to a circulation adapter 25 in the bathtub 20. The other end of the return pipe 8a is connected to the input side of the heat exchanger 4b. One end of the forward pipe 8b is connected to the output side of the heat exchanger 4b. The other end of the forward pipe 8b is connected to the circulation adapter 25.

[0028] By operating the circulation pump 10, a path (reheating circulation path) is formed in which bath water 21 drawn in from the circulation adapter 25 passes through the return pipe 8a, the heat exchanger 4b, and the forward pipe 8b, and is discharged from the circulation adapter 25. When the reheating circulation path is formed, the controller 12 starts the combustion operation of the burner 2b, and the heat exchanger 4b heats the bath water 21 introduced from the return pipe 8a. The heated bath water 21 is supplied to the bathtub 20 by the forward pipe 8b. In this way, a reheating operation is performed to raise the temperature of the bath water 21.

[0029] The temperature sensor 9 and the water level sensor 11 are provided in the return pipe 8a. The temperature sensor 9 detects the temperature of the bathtub water 21. The water level sensor 11 is composed of, for example, a pressure sensor. The water level sensor 11 detects the water level of the bathtub water 21 in the bathtub 20 (hereinafter also simply referred to as the "bathtub water level") based on the water pressure of the bathtub water 21. The temperature sensor 9 and the water level sensor 11 are disposed in an area of ​​the return pipe 8a into which the bathtub water 21 enters even when the circulation pump 10 is stopped.

[0030] Return pipe 8a is further connected to hot water supply pipe 13a at connection point 8c. As a result, when water heater 110 pours hot water while circulation pump 10 is stopped, a first hot water supply path is formed from pouring pipe 13a to bathtub 20 via connection point 8c and return pipe 8a, and a second hot water supply path is formed from pouring pipe 13a to bathtub 20 via connection point 8c, return pipe 8a, heat exchanger 4b, and forward pipe 8b. This allows the bath to be filled by pouring hot water from hot water heater 110.

[0031] In this way, hot and cold water from water heater 110 (hot water pouring circuit) is supplied to bathtub 20 via the first and second hot water pouring paths, including circulation path 8. Bathtub 20 is provided with a drain plug 26. Drain plug 26 can be configured as either a "manual drain plug" that is opened and closed by manual operation by the user, or an "automatic drain plug" that can also be opened and closed automatically in response to an operation command from controller 12.

[0032] Controller 12 includes, for example, a microcomputer, a processor, or other arithmetic processing circuit. Controller 12 is electrically connected to burners 2a, 2b, fans 3a, 3b, temperature sensors 9, 18, 19, 80, circulation pump 10, water level sensor 11, bath hot water valve 13, and electrical wiring 14. Electrical wiring 14 is connected to a power source (not shown) to supply power to controller 12. Controller 12, as a control device, controls each operation of hot water supply device 110.

[0033] The controller 12 receives inputs of detection values ​​from the flow rate sensors 15, 16 and the temperature sensors 9, 12T, 18, 19, and 80. The flow rate sensors 15, 16 are realized, for example, by impeller-type flow meters. The temperature sensors 9, 12T, 18, 19, and 80 are realized, for example, by thermistors. The temperature sensor 12T is provided in the housing 1 which is usually placed outdoors. The temperature sensor 12T measures the atmospheric temperature (outside air temperature) which changes with the seasons.

[0034] The controller 12 obtains the inlet water temperature Tw from the detection value of the temperature sensor 18. The controller 12 obtains the outlet hot water temperature Th from the detection value of the temperature sensor 19. The controller 12 obtains the temperature of the bathtub water 21 from the detection value of the temperature sensor 9. The controller 12 obtains the outside air temperature Tar from the detection value of the temperature sensor 12T. The controller 12 calculates the amount (volume) of hot water poured into the bathtub 20 by integrating the flow rate (pouring hot water flow rate) detected by the flow rate sensor 16. The controller 12 obtains the temperature of the hot water after it has been heated by the heat exchanger 4b, based on the detection value of the temperature sensor 80.

[0035] Furthermore, the controller 12 is communicably connected to a remote control 30 and a remote control 50. Note that the communication between these devices may be in accordance with a known standard. The form of communication may be either wired or wireless.

[0036] Remote control 30 is installed on the wall of bathroom 200 and controls water heater 110 based on user operation. Remote control 30 includes display unit 31 for displaying information and operation unit 32 for accepting input setting operations from a user or installer. Display unit 31 is, for example, a liquid crystal panel, and displays the bath water level and set temperature. Operation unit 32 is, for example, realized by a push button or a touch button. Operation unit 32 is configured to be able to accept setting operations related to the bath water level and temperature. In still another aspect, remote control 30 may include a human presence sensor 35 for detecting the presence of a person in the bathroom. In this case, human presence sensor 35 may be realized by, for example, an infrared sensor.

[0037] Remote control 50 is installed outside bathroom 200. Remote control 50 controls water heating apparatus 110 in response to a user's operation. Remote control 50 is typically installed on a wall in the kitchen. Remote control 50 includes a display unit 51 for displaying information and an operation unit 52 for receiving input setting operations from a user or the like.

[0038] Display unit 51 is realized by, for example, a liquid crystal panel. Display unit 51 can display the hot water supply temperature setting, the bath temperature setting, and other information. Operation unit 52 is typically configured by push buttons or touch buttons, and is configured to be able to accept setting operations related to the operation of water heating device 110.

[0039] Based on input setting operations by a user or the like from remote controls 30, 50, controller 12 controls the operation of water heating device 110 so that water heating system 100 operates in accordance with the input instructions.

[0040] As an example of this control, the controller 12 executes a bath filling operation when it receives an instruction for automatic bath operation via the operation of the remote controls 30, 50. The bath filling operation ends when the water level in the bathtub 20 reaches the set water level due to hot water poured from the water heater 110 and the temperature of the bathtub water detected by the temperature sensor 9 reaches the set bath temperature.

[0041] After the bath filling operation is completed, the water heater 110 can be set to an automatic mode in which the temperature and water level of the bathtub water 21 are maintained. When this automatic mode is selected, if the temperature of the bathtub water 21 detected by the temperature sensor 9 falls below a reference temperature set in accordance with the bath setting temperature (for example, set 2 to 3°C lower than the bath setting temperature), a reheating operation is automatically started to control the temperature retention. Furthermore, if the water level of the bathtub water 21 detected by the water level sensor 11 falls below the set water level, a hot water top-up operation is started to supply additional hot water from the water heater 110 to the bathtub 20.

[0042] After draining bathtub 20, hot water supply system 100 according to this embodiment can perform a pipe cleaning operation by pouring hot water from hot water supply device 110 to clean the inside of the pipes, including circulation path 8. In the pipe cleaning operation according to this embodiment, the user can select from a number of cleaning modes in which the supply amount and temperature of cleaning water are set to different amounts.

[0043] <Controller> The configuration of the controller 12 will be described with reference to Fig. 2. Fig. 2 is a block diagram illustrating the configuration of the controller 12 according to an embodiment. The controller 12 includes a processor 210 and a memory 220.

[0044] Processor 210 executes instructions contained in a program stored in memory 220 and controls the operation of water heating apparatus 110 based on data stored in memory 220 .

[0045] Memory 220 holds a program having instructions for controlling the operation of water heating apparatus 110, and setting data input to water heating apparatus 110. The setting data includes, for example, bath setting temperature 221, learned value 222 of heat retention interval time, and target temperature offset value 223.

[0046] Bath set temperature 221 is used in the automatic filling operation of bathtub 20. Bath set temperature 221 can be changed by a user of hot water supply system 100 or a bather. As an example, in one aspect, bath set temperature 221 can be set to Ts° C. (e.g., 42° C.).

[0047] The learned value 222 of the heat-keeping interval time represents the latest heat-keeping interval time updated by the operation of the hot water supply system 100. When the hot water supply system 100 is initially set up, or when the data in the controller 12 is erased and new initial data is installed, the heat-keeping interval time is set to a predetermined time, for example, 20 minutes, 30 minutes, etc.

[0048] The target temperature offset value 223 is a difference value for setting the bath target temperature during heat retention operation to a temperature different from the bath set temperature 221. As an example, the target temperature offset value 223 is set to 2°C. This difference value is used, for example, when the supply of hot water to the bathtub 20 is controlled in two stages. As an example, the two-stage supply control means that before a person's bathing is detected, hot water at a temperature lower than the bath set temperature 221 is supplied, and when a person's bathing is detected, reheating is performed until the bath set temperature 221 is reached. For example, when the hot water supply system 100 starts reheating operation, if the two-stage supply is set to ON and the target temperature offset value 223 is set to 2°C, the controller 12 sets the bath target temperature to 40°C (=42°C-2°C). When the hot water supply system 100 detects that someone is taking a bath, it sets the bath target temperature to the bath set temperature 221 and continues the reheating operation until the temperature of the hot water in the bathtub 20 reaches 42°C.

[0049] <Control Structure> The control structure of water heating apparatus 110 will be described with reference to Fig. 3. Fig. 3 is a flow chart showing a part of the processing executed by controller 12.

[0050] In step S310, the processor 211 of the controller 12 detects that hot water has been supplied up to a preset water level based on the output from the temperature sensor 9 and the output from the water level sensor 11, and completes the automatic bath operation (water filling operation). The heat retention function is set to enabled.

[0051] In step S315, the processor 211 uses the timer function to obtain the warming time ts that has elapsed since the automatic bath operation was completed.

[0052] In step S320, the processor 211 acquires the bath setting temperature 221 (Ts (° C.)) from the memory 220.

[0053] In step S325, the processor 211 sets the bath target temperature Ta using the bath setting temperature 221. In one aspect, the processor 211 calculates the bath target temperature Ta by the following formula. Bath target temperature (Ta) = Bath set temperature (Ts) - target temperature offset value (α) When the two-stage supply control function is enabled (ON), the CPU 1 reads the target temperature offset value (α) from the memory 220 and calculates the bath target temperature Ta. When the two-stage supply control function is disabled (OFF), the CPU 1 calculates the bath target temperature Ta assuming that the target temperature offset value (α) is zero.

[0054] In step S330, processor 211 sets an initial value to warming interval time ti. For example, depending on whether warming interval time ti is zero or not, processor 211 sets the initial value as follows. When ti≠0, ti=A (initial value) When ti=0, ti=previous value ti=0 is, for example, the time when hot water supply system 100 first performs a hot water filling operation and starts heat retention.

[0055] In step S335, the processor 211 starts measuring the warming interval time ti.

[0056] In step S340, processor 211 determines whether or not warming interval time ti (minutes) has elapsed since the start of measurement. If processor 211 determines that warming interval time ti (minutes) has elapsed since the start of measurement (YES in step S340), it switches control to step S345. If not (NO in step S340), processor 211 switches control to step S370.

[0057] In step S345, the processor 211 starts the non-combustion bath circulation operation. As an example, the hot water supply system 100 operates the circulation pump 10 without performing the combustion operation by the burners 2a and 2b.

[0058] In step S350, the processor 211 acquires the bath return temperature (Tcx) as the temperature of the hot and cold water in the bathtub 20 based on the output of the temperature sensor 9.

[0059] In step S355, processor 211 determines whether or not bath return temperature (Tcx) is equal to or lower than bath set temperature (Ts). If processor 211 determines that bath return temperature (Tcx) is equal to or lower than bath set temperature (Ts) (YES in step S355), processor 211 switches control to step S360. If not (NO in step S355), processor 211 switches control to step S365.

[0060] In step S360, the processor 211 calculates the warming interval time ti using the following formula. ti = {ΔT / (Ts-Tcx)} × ti (previous value) however, ΔT: constant tmin≦ti≦tmax In step S365, the processor 211 sets the warming interval time ti=A.

[0061] In step S370, processor 211 determines whether or not there has been a reheating request. If processor 211 determines that there has been a reheating request (YES in step S370), it switches control to step S375. If not (NO in step S370), processor 211 returns control to step S340.

[0062] In step S375, processor 211 determines whether the re-heating request is temperature control increased re-heating based on an instruction from remote control 30. In the present embodiment, temperature control increased re-heating refers to re-heating provided by a user operating remote control 30 when he or she wishes to immediately increase the temperature of the hot and cold water in bathtub 20. If processor 211 determines that the re-heating request is temperature control increased re-heating (YES in step S375), it switches control to step S380. If not (NO in step S375), processor 211 switches control to step S390.

[0063] In step S380, processor 211 updates the bath set temperature (Ts). For example, processor 211 changes the bath set temperature (Ts) from 40° C. to 42° C., for example, based on an instruction for setting the temperature given to remote control 30.

[0064] In step S385, the processor 211 updates the bath target temperature Ta using the following equation. Bath target temperature (Ta) = Bath set temperature (Ts) - target temperature offset value (α) This process is performed when hot water supply system 100 is of a fully automatic type.

[0065] In step S390, the processor 211 executes the heat retention and reheating operation. In step S395, processor 211 determines whether or not warming time ts has elapsed. If processor 211 determines that warming time ts has elapsed (YES in step S395), it ends the control. If not (NO in step S395), processor 211 returns control to step S335.

[0066] As described above, according to this embodiment, processor 211 calculates the amount of water temperature change (Ts-Tcx) after the warmth-retention interval time ti has elapsed, using bath set temperature Ts and the temperature Tcx of the hot and cold water in bathtub 20 measured immediately before the warmth-retention reheating operation. Processor 211 calculates the next warmth-retention interval time ti from the calculated amount of water temperature change and the reference amount of water temperature change ΔT, using the following formula: ti = {ΔT / (Ts-Tcx)} × ti (previous value) At this time, the processor 211 uses the initial value A (minutes) as the first ti.

[0067] The processor 211 calculates the heat retention interval time ti every time the heat retention and reheating operation is performed. The processor 211 updates the heat retention interval time with the value obtained by the calculation, and uses the latest heat retention interval time in the next heat retention and reheating operation.

[0068] Furthermore, the processor 211 stores the calculated warming interval time ti in the memory 220 as a learned value.

[0069] (1) In this way, the water temperature change (Ts-Tcx) immediately before the start of the warm-keeping reheating operation is sufficiently larger than the water temperature change immediately after the conventional reheating operation. This reduces the effect of sensor variation, which can improve the accuracy of the calculation of the warm-keeping interval time.

[0070] (2) In hot water supply system 100 according to the present embodiment, processor 211 learns (stores in memory 220) the calculated heat retention interval time ti, and uses that heat retention interval time ti the next time heat retention operation is performed. This allows hot water supply device 110 to perform the first heat retention operation after automatic bath operation is completed at an appropriate timing. Note that the first heat retention operation after automatic bath operation is completed is, for example, the first heat retention operation in automatic bath operation performed the day after automatic bath operation was performed.

[0071] (3) If another reheating operation is performed during the warm-keeping operation, the processor 211 resets the warm-keeping interval time ti being measured and starts measuring the warm-keeping interval time ti again. This makes it possible to eliminate unnecessary warm-keeping reheating operations.

[0072] <Screen display example> A display mode of a screen on remote control 30 of water heating apparatus 110 will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of a screen displayed on display unit 31 of remote control 30.

[0073] When hot water supply apparatus 110 starts the heat retention and reheating operation, in a certain aspect, processor 211 may output a sound from a speaker (not shown) of remote control 30 and display message 410 indicating that on remote control 30. If the user taking a bath thinks that it is OK for the heat retention and reheating operation to start, there is no need to operate remote control 30 in any way.

[0074] If the user decides that he / she wants to delay the start of the heat retention re-heating operation, he / she can touch the soft switch 420 to instruct the extension of the heat retention re-heating operation. In this case, the processor 211 delays the start of the heat retention re-heating operation for a predetermined time (for example, 5 minutes). On the other hand, if the user decides that the heat retention re-heating operation is unnecessary, he / she can touch the soft switch 430 to stop the heat retention re-heating operation. For example, if the user is the last person to take a bath that day, the heat retention re-heating operation is unnecessary. Therefore, the user can use the soft switch 430 to stop the heat retention re-heating operation.

[0075] As described above, water heating apparatus 110 according to the present embodiment uses the amount of change in water temperature before the start of the re-heating operation, and therefore the accuracy of calculation of the heat retention interval can be improved.

[0076] Water heating apparatus 110 updates the heat retention interval time each time heat retention reheating operation is performed. Therefore, even when the amount of heat radiation from the bathtub water temperature changes due to operation of a bathroom heater / dryer or the like (i.e., when the temperature of the hot water in bathtub 20 is difficult to lower), water heating apparatus 110 can adopt an appropriate heat retention interval time according to the change.

[0077] Since hot water supply device 110 learns the warmth interval time, the first warmth operation after the next automatic bath operation ends will also be performed at an appropriate time.

[0078] When another reheating operation is performed during heat retention, water heating apparatus 110 resets the heat retention interval time ti being measured and starts measuring heat retention interval time ti again. This prevents water heating apparatus 110 from performing unnecessary reheating operation, and fuel consumption can be reduced.

[0079] In one aspect, when water heating apparatus 110 is a fully automatic type bath water heater, water heating apparatus 110 lowers the bath target temperature during heat retention operation by α° C. (constant), as shown in step S325, thereby preventing unnecessary energy consumption.

[0080] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0081] The disclosed technical features can be applied to a hot water supply device having a reheating function. [Explanation of symbols]

[0082] 1 housing, 1a exhaust port, 2, 2a, 2b burner, 3, 3a, 3b fan, 4, 4a, 4b heat exchanger, 5 water inlet pipe, 5a water inlet, 5b boiler body pipe, 6 hot water supply pipe, 6a hot water outlet, 7 bypass valve, 7a bypass pipe, 8 circulation path, 8a pipe, 8a return pipe, 8b forward pipe, 8c connection point, 9, 12T, 18, 19, 80 temperature sensor, 10 circulation pump, 11 water level sensor, 12 controller, 13 hot water valve, 13a hot water pipe, 14 electrical wiring, 15, 16 flow rate sensor, 20 bathtub, 21 bathtub water, 25 circulation adapter, 26 drain plug, 30, 50 remote control, 31, 51 display unit, 32, 52 operation unit, 35 human presence sensor, 100 hot water supply system, 110 Water heater, 200 bathroom, 210, 211 processor, 220 memory, 221, Ts bath setting temperature, 222 learning value, 223 target temperature offset value.

Claims

1. A hot water supply device, comprising: A combustion unit that heats water and supplies hot water to the bathtub; A circulation pump that sends hot and cold water from the bathtub to the combustion unit; A control device for controlling the operation of the hot water supply device, The operation is A bath filling operation for supplying hot water at a predetermined temperature to the bathtub; and a heat retention operation for operating the combustion unit and the circulation pump so that the temperature of the hot water in the bathtub rises to a predetermined set temperature at intervals of a predetermined heat retention interval from the completion of the water filling operation to the start of the heat retention operation. The control device includes: The temperature of the hot water in the bathtub is acquired before the heat retention operation; Calculating the amount of change in the temperature of the hot and cold water in the bathtub based on the acquired hot and cold water temperature and the set temperature; The hot water supply device calculates a heat-retention interval time until the start of a next heat-retention operation based on the amount of change, a preset reference amount of water temperature change, and the heat-retention interval time.

2. The hot water heater according to claim 1 , wherein the heat retention interval time is calculated every time the heat retention operation is started.

3. A memory for storing the calculated warming interval time is further provided, The water heating device of claim 1 or 2, wherein calculating the heat retention interval time until the start of the next heat retention operation includes calculating the heat retention interval time using the heat retention interval time stored in the memory after the water filling operation performed after the next heat retention operation is completed.

4. The operation of the hot water supply apparatus further includes a reheating operation, The hot water supply device according to claim 1 or 2, wherein calculating the heat retention interval time until the start of the next heat retention operation includes calculating a new heat retention interval time based on the fact that the reheating operation is performed while the heat retention operation is being performed.

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