Hot water system

Abstract

To provide a hot water system capable of restraining consumption of fuel gas relating to hot-water supply, reducing an emission amount of carbon dioxide accompanied with combustion of a water heater, and efficiently utilizing hot water in a tank, even when the tank is miniaturized.SOLUTION: A controller 4 determines whether a bathtub 41 and a bath room are included as a use portion and whether hot water is supplied to the use portion in a bath room use time zone in which the hot water is used in the bath room. The controller 4 does not use the hot water stored in a tank 1, and heats tap water with a water heater 3 into hot water and supplies the hot water to the use portion, when it is determined that the hot water is supplied in the bath room use time zone. Also, when a hot water addition button 54 is operated by a remote controller 5, the hot water in the tank 1 is added to a bathtub 41 even in the bath room use time zone.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hybrid hot water supply system comprising a hot water heater equipped with a burner and capable of heating passing water, and a tank equipped with a heat pump and storing the heated hot water. [Background technology]

[0002] Conventionally, a heat pump-type hot water supply system has been put into practical use, which includes a heat pump and a tank for storing hot water heated by the heat pump, and supplies hot water in the tank to a kitchen, a bathroom, etc. However, in the conventional heat pump-type hot water supply system, there is a problem that the tank must be very large in size in order to store a large amount of hot water required when filling a bathtub. Therefore, as described in Patent Document 1, for example, a hybrid hot water supply system has been devised in which a burner heating device, which is a hot water heater, is installed in the supply path downstream of the tank in which the hot water is stored. In the hybrid hot water supply system described in Patent Document 1, if the amount of hot water in the tank is low when filling the bathtub, the burner heating device is operated in addition to heating by the heat pump to make up for the lack of hot water, and as a result, the tank can be made smaller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-224762 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the hot water supply system described in Patent Document 1, the tank in which hot water is stored can be made smaller. However, when the tank is made smaller, the amount of hot water in the tank is likely to be insufficient during hot water supply operation in the bathroom, where hot water is used in large quantities, such as when filling the bathtub or using a shower. When the amount of hot water in the tank is insufficient, the water heater is operated as described above to make up for the lack of hot water. However, when tap water is heated to a set temperature for hot water supply, the consumption of fuel gas increases, and the amount of carbon dioxide emitted by the combustion in the water heater increases. Therefore, when supplying hot water in the bathroom, the hot water stored in the tank is first supplied, and when the hot water is insufficient, tap water is heated to supply hot water, which is a problem in terms of reducing carbon dioxide emissions. In particular, in a system that employs a small tank in which the amount of hot water in the tank is likely to be insufficient, the problem is more pronounced. On the other hand, although the hot water supply operation is performed in the bathroom, the hot water in the tank is considered to be sufficient for so-called top-up, so there is also the problem of wanting to efficiently use the hot water in the tank.

[0005] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a hot water supply system that can reduce the amount of fuel gas consumed for hot water supply even if the tank is made smaller, thereby reducing carbon dioxide emissions associated with combustion in the water heater, and can efficiently utilize the hot water in the tank. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the invention described in claim 1 of the present invention is a hot water supply system comprising a tank for storing hot water, a heat pump for heating the hot water in the tank, a water heater for heating the supplied hot water using the heat of combustion of fuel gas, a first supply path for supplying the hot water in the tank to a specified point of use, and a second supply path for heating tap water in the water heater without going through the tank and then supplying it to the point of use, and a control means for controlling the operation of the water heater and the selection of the supply paths, wherein the points of use include a bathroom and a bathtub, and the system is equipped with a time zone discrimination means for discriminating whether hot water is being supplied to the point of use during a bathroom usage time zone when hot water is used in the bathroom, and a command means for commanding the control means, and when the control means determines that hot water is being supplied during a bathroom usage time zone, it does not use the hot water stored in the tank and supplies hot water to the point of use via the second supply path, while when the command means commands hot water to be added to the bathtub, hot water is added to the bathtub via the first supply path even during the bathroom usage time zone. In addition, in order to achieve the above-mentioned object, the invention described in claim 2 of the present invention is a hot water supply system comprising a tank for storing hot water, a heat pump for heating the hot water in the tank, a water heater for heating the supplied hot water using the heat of combustion of fuel gas, a first supply path for supplying the hot water in the tank to a specified point of use, and a second supply path for heating tap water in the water heater without going through the tank and then supplying it to the point of use, and a control means for controlling the operation of the water heater and the selection of the supply paths, wherein the points of use include a bathroom and a bathtub, and the system is equipped with a time zone discrimination means for discriminating whether hot water is being supplied to the point of use during a bathroom usage time zone when hot water is used in the bathroom, and a command means for commanding the control means, and when the control means determines that hot water is being supplied during a bathroom usage time zone, it does not use the hot water stored in the tank and supplies hot water to the point of use via the second supply path, while when the command means commands hot water to be added to the bathtub and when a predetermined condition is satisfied, hot water is added to the bathtub via the first supply path even during the bathroom usage time zone. Effect of the Invention

[0007] According to the present invention, the places of use include the bathtub and the bathroom, and a time zone determination means is provided for determining whether hot water is to be supplied to the places of use during the bathroom use time zone when hot water is used in the bathroom. When the control means determines that hot water is to be supplied during the bathroom use time zone, it does not use the hot water stored in the tank and supplies hot water to the places of use through the second supply path. Therefore, when supplying hot water during the bathroom use time zone when hot water is used a lot, the hot water in the tank is basically not used, so that the hot water in the tank is unlikely to run out, that is, the amount of hot water in the tank becomes small or the temperature of the hot water in the tank becomes low, and the hot water in the tank can be used very efficiently. In addition, if the hot water in the tank runs out while it is being used and hot water is switched to hot water heated by the water heater, the temperature of the hot water will temporarily change significantly at the time of switching, but since such a situation is unlikely to occur, the hot water supply system is unlikely to cause discomfort to the user. Furthermore, a command means is provided to command the control means, and when the control means commands the control means to add hot water to the bathtub (claim 1), or when the command means commands the control means to add hot water to the bathtub and a predetermined condition is satisfied (claim 2), the control means adds hot water to the bathtub via the first supply path even during the time period the bathroom is in use. In other words, the hot water in the tank is used for adding hot water, which uses less hot water than filling the bath, and therefore the hot water in the tank can be used efficiently to provide a hot water supply system. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing an outline of a hot water supply system. [Diagram 2] This is a table showing the start time of hot water supply, the amount of hot water produced, etc. for a typical four-person household. [Diagram 3] 4 is a flowchart showing control related to hot water supply operation by a controller. [Figure 4] 4 is a flowchart showing control of the filling operation by the controller. [Diagram 5]11 is a flowchart showing the control of hot water addition operation by the controller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hot water supply system according to an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of a hot water supply system S. As shown in FIG. The hot water supply system S comprises a tank 1 for storing hot water, a heat pump 2 for heating the hot water in the tank 1, a water heater 3 for heating the supplied hot water by burning a fuel gas, a controller 4, and a remote control 5. The capacity of the tank 1 is 20 L, which is sufficiently smaller than the capacity of a typical bathtub 41. A water supply pipe 6 connected to an external water pipe is also connected to the tank 1. The heat pump 2 is a known device that includes an evaporator, a compressor, a heat exchanger, etc., and heats the passing water by heat exchange between a heat medium and the passing water, and has an output of 2.0 kW.

[0010] A tank forward pipe 7 is connected between the top of the tank 1 and the outlet of the heat pump 2, and a tank return pipe 8 is connected between the bottom of the tank 1 and the inlet of the heat pump 2. The tank forward pipe 7 and the tank return pipe 8 form a circulation path 9 in which hot water circulates between the tank 1 and the heat pump 2. The tank return pipe 8 is provided with a pump 10 for circulating hot water and a return temperature thermistor 11 for detecting the temperature of the hot water in the tank return pipe 8. The upper part of the tank 1 is connected to a relay pipe 12 connected to a hot water heat exchanger 23 of the water heater 3 described later. The relay pipe 12 is provided with a relay temperature thermistor 13 for detecting the temperature of the hot water flowing in the relay pipe 12 and a relay flow rate sensor 14 for detecting the flow rate of the hot water flowing in the relay pipe 12. A direct water supply pipe 15 is connected between a point on the relay pipe 12 upstream of the water heater 3 and the water supply pipe 6 to bypass the tank 1 and directly supply water in the water supply pipe 6 to the water heater 3 side. Furthermore, a switching solenoid valve 16 is provided at the connection between the relay pipe 12 and the direct water supply pipe 15, which can switch between supplying hot water in the tank 1 to the hot water heat exchanger 23 side or supplying tap water from the direct water supply pipe 15 to the hot water heat exchanger 23 side. Note that the switching solenoid valve 16 is normally in a switching state in which the hot water in the tank 1 is supplied to the hot water heat exchanger 23 side.

[0011] When the remote control 5 is operated to instruct heat-retention operation by the heat pump 2, the controller 4 operates the heat pump 2 and the pump 10. Then, the hot water in the tank 1 circulates through the circulation path 9 and is heated as it passes through the heat pump 2. The hot water in the tank 1 is once heated to a high temperature (e.g., 75°C) in the heat pump 2, and then the heat pump 2 is turned ON / OFF based on the temperature detected by the return temperature thermistor 11, thereby maintaining the water at a predetermined heat-retention temperature (e.g., 65°C).

[0012] On the other hand, the water heater 3 includes a water heater 20 and a bath heater 21. The water heater 20 includes a water burner 22 and a water heat exchanger 23, and the relay pipe 12 is connected to the inlet of the water heat exchanger 23. A hot water outlet pipe 26 is connected to the outlet of the water heat exchanger 23, and a hot water outlet temperature thermistor 27 for detecting the temperature of hot water and a hot water outlet flow rate sensor 32 for detecting the flow rate of hot water flowing through the hot water outlet pipe 26 are provided on the hot water outlet pipe 26. An external pipe 28 is connected to the hot water outlet pipe 26, and is provided with a plurality of hot water taps 29, each of which is arranged in a washroom, kitchen, bathroom, etc. Furthermore, a mixing pipe 30 is connected between the hot water outlet pipe 26 and a point upstream of the switching solenoid valve 16 in the direct water supply pipe 15, to supply tap water into the hot water outlet pipe 26 to adjust the hot water outlet temperature. A water volume control valve 31 capable of controlling the volume of water flowing from the direct water supply pipe 15 to the mixing pipe 30 is provided at the connection between the direct water supply pipe 15 and the mixing pipe 30 .

[0013] The bath heating section 21 has a bath burner 24 and a bath heat exchanger 25. A bath return pipe 42 is connected between the inlet of the bath heat exchanger 25 and the external bathtub 41. A circulation pump 43 and a bath temperature thermistor 44 are provided in the bath return pipe 42. A bath supply pipe 45 is connected between the outlet of the bath heat exchanger 25 and the bathtub 41. The bath return pipe 42 and the bath supply pipe 45 form a reheating circulation path 46 in which hot water circulates between the bath heat exchanger 25 and the bathtub 41. A drop pipe 47 is connected between the bath return pipe 42 and the hot water outlet pipe 26. A drop solenoid valve 48 and a drop flow rate sensor 49 are provided in the drop pipe 47.

[0014] Furthermore, gas pipe 34, which supplies fuel gas to hot water burner 22 and bath burner 24, branches into hot water branch pipe 35 on the hot water heating section 20 side and bath branch pipe 36 on the bath heating section 21 side. Hot water branch pipe 35 supplies fuel gas to hot water burner 22, and bath branch pipe 36 supplies fuel gas to bath burner 24. Hot water branch pipe 35 is provided with hot water gas switching valve 37, and bath branch pipe 36 is provided with bath gas switching valve 38. In addition, a main solenoid valve 39 and a proportional control valve 40 are provided from the upstream side in gas pipe 34 before branching.

[0015] The remote control 5 is operated by the user as appropriate, and is provided with, for example, a setting button 51 for setting the hot water temperature, a filling button 52 for instructing the bathtub 41 to be filled with hot water, a reheating button 53 for instructing the reheating of the hot water in the bathtub 41, and a hot water addition button 54 for instructing the addition of hot water to the bathtub 41. The controller 4 is configured to include a CPU, a storage means, a timer, etc., and is electrically connected to each thermistor, each sensor, and each valve. The controller 4 performs a warming operation of the hot water in the tank 1, a hot water supply operation to supply hot water from the hot water tap 29, a hot water filling operation to fill the bathtub 41 with hot water, a reheating operation to reheat the hot water in the bathtub 41, and a hot water addition operation to add hot water to the bathtub 41, etc., according to a program stored in a non-transient computer-readable storage medium that is a part of the storage means.

[0016] Before explaining the control of various operations by the controller 4, we will explain the actual hot water usage as disclosed in JIS2075, that is, a standard model of how 40°C hot water is used in a day in a typical household of four people, based on Figure 2. Figure 2 is a table showing the start time of hot water supply, the amount of hot water discharged, etc., in a typical household of four people.

[0017] JIS2075 is a regulation on the method of measuring the modal efficiency of domestic gas and oil hot water appliances, and is a method of measuring the efficiency of hot water appliances using a standard usage mode that reflects the way hot water is used in an ordinary household. Therefore, the hot water usage pattern disclosed in JIS2075 can be used as a standard model of how 40°C hot water is used in a day in a typical four-person household. Therefore, the time period from 19:00 to 24:00 is preset in the controller 4 as the time period for bathroom use.

[0018] The hot water supply operation, hot water filling operation, and hot water topping up operation performed by the controller 4 for which such bathroom usage time zones are set will now be described with reference to the flowcharts shown in Figures 3 to 5. Figure 3 is a flowchart showing the control of the hot water supply operation performed by the controller 4. Figure 4 is a flowchart showing the control of the hot water filling operation performed by the controller 4. Figure 5 is a flowchart showing the control of the hot water topping up operation performed by the controller 4.

[0019] First, the hot water supply operation will be described. When the hot water tap 29 is opened and the relay flow rate sensor 14 detects water flow (S1), the controller 4 judges whether the current time is within the learned bathroom use time zone (S2). If the current time is not within the bathroom use time zone (NO in S2), the controller 4 judges whether the temperature of the hot water in the circulation path 9, i.e., the temperature detected by the return temperature thermistor 11, is equal to or higher than a predetermined warming temperature (S3). If the temperature is equal to or higher than the warming temperature (YES in S3), the controller 4 does not ignite the hot water burner 22 and flows the hot water in the tank 1 to the hot water outlet pipe 26 through the hot water heat exchanger 23 while maintaining the switching state of the switching solenoid valve 16 so that the hot water in the tank 1 is supplied to the hot water heat exchanger 23 side. In other words, the hot water in the tank 1 is not heated by the hot water heat exchanger 23 and flows directly to the hot water outlet pipe 26 (S6). In addition, since the temperature of the hot water in the tank 1 flowing through the hot water outlet pipe 26 is relatively high, above the insulation temperature as described above, it is considered that it is often higher than the set temperature set by the remote control 5. Therefore, when the hot water temperature detected by the outlet hot water temperature thermistor 27 is higher than the set temperature set by the remote control 5, the water volume control valve 31 is controlled to a predetermined opening degree, tap water is directly flowed from the water supply pipe 15 to the mixing pipe 30, and mixed with the hot water in the hot water outlet pipe 26 to adjust to the set temperature. This hot water supply control in which the hot water in the tank 1 is supplied without being heated by the water heater 3 is called the tank use mode. After that, the hot water supply tap 29 is closed and the stop of water flow is detected by the outlet hot water flow rate sensor 32 (S7), and the hot water supply operation in the tank use mode is terminated.

[0020] Also, if the temperature detected by the return temperature thermistor 11 is lower than the insulation temperature (determined as NO in S3), the switching solenoid valve 16 is controlled to stop the supply of hot water in the tank 1 to the hot water heat exchanger 23 side, and instead, the tap water is switched to be supplied directly from the water supply pipe 15 to the hot water heat exchanger 23 side. That is, the use of hot water in the tank 1 is stopped (S4). Also, the main solenoid valve 39 and the hot water gas switching valve 37 of the gas pipe 34 are opened, and the proportional control valve 40 is opened at a predetermined opening degree to supply fuel gas to the hot water burner 22. Furthermore, the igniter is operated to ignite the hot water burner 22. Then, the tap water passes from the water supply pipe 6 through the direct water supply pipe 15 to the relay pipe 12 and then to the hot water heat exchanger 23, and flows to the hot water outlet pipe 26 after being heated by heat exchange with the combustion exhaust gas while passing through the hot water heat exchanger 23 (S5). At this time, the temperature of the hot water after being heated by the hot water heat exchanger 23 and flowing through the hot water outlet pipe 26 becomes higher than the set temperature set by the remote control 5. Therefore, when the hot water outlet temperature thermistor 27 detects such a high hot water temperature, the water volume control valve 31 is controlled to a predetermined opening degree, tap water is directly flowed from the water supply pipe 15 to the mixing pipe 30, and mixed with the hot water in the hot water outlet pipe 26 to adjust to the set temperature. This hot water supply control in which tap water is heated by the hot water heater 3 before being discharged is called the hot water supply use mode. After that, when the hot water tap 29 is closed and the stop of water flow is detected by the hot water outlet flow rate sensor 32 (S7), the combustion of the hot water burner 22 is stopped and the switching solenoid valve 16 is controlled to return to the initial state, that is, the state in which the hot water in the tank 1 is supplied to the hot water heat exchanger 23 side, and the hot water supply operation in the hot water supply use mode is terminated.

[0021] On the other hand, if the result of the determination after the water flow in the relay pipe 12 is that the current time is within the bathroom use time period (YES in S2), the hot water supply operation in the hot water supply use mode is executed. That is, the switching solenoid valve 16 is controlled to stop the use of hot water in the tank 1 and supply tap water to the hot water heat exchanger 23 (S4). In addition, the hot water burner 22 is ignited, the tap water is heated in the hot water heat exchanger 23, and then flows into the hot water outlet pipe 26 (S5), where it is mixed with the tap water supplied through the mixing pipe 30 to adjust the temperature, and then hot water is discharged from the hot water tap 29. After that, when the hot water tap 29 is closed and the water flow stop is detected by the hot water outlet flow rate sensor 32 (S7), the combustion of the hot water burner 22 is stopped, and the switching solenoid valve 16 is controlled to return to the initial state, that is, the state in which the hot water in the tank 1 is supplied to the hot water heat exchanger 23 side, and the hot water supply operation in the hot water supply use mode is terminated.

[0022] Next, the filling operation will be described. When the controller 4 detects the operation of the filling button 52 by the user (S11), it executes the operation in the hot water supply mode. That is, it controls the switching solenoid valve 16 to stop the use of hot water in the tank 1 and supply tap water to the hot water heat exchanger 23 (S12). In addition, it ignites the hot water burner 22, heats the tap water in the hot water heat exchanger 23, and then flows it to the hot water outlet pipe 26 (S13), and mixes it with the tap water supplied through the mixing pipe 30 in the same manner as above to adjust the temperature. In addition, the controller 4 opens the drop solenoid valve 48 of the drop pipe 47 to start dropping the water into the bathtub 41. Therefore, the hot water heated through the hot water heat exchanger 23 flows from the outlet pipe 26 to the drop pipe 47, and is supplied to the bathtub 41 from the bath return pipe 42. In addition, the controller 4 determines that filling the bathtub is complete when the flow rate detected by the drop-down flow sensor 49 reaches a preset amount of hot water (determines YES in S14), closes the drop-down solenoid valve 48, and stops the combustion of the hot water burner 22, thereby ending the supply of hot water to the bathtub 41, i.e., the filling operation.

[0023] Since it is assumed that the user will operate the filling button 52 during the hours the bathroom is in use, the filling operation described above can be considered the same as the hot water supply operation during the hours the bathroom is in use. Furthermore, when the filling operation is completed, the switching state of the switching solenoid valve 16 is returned to the state in which the hot water in the tank 1 is supplied to the hot water supply heat exchanger 23 side.

[0024] The hot water addition operation will be further explained. When the controller 4 detects the operation of the hot water addition button 54 by the user (S21), it judges whether the temperature detected by the return temperature thermistor 11 is equal to or higher than the predetermined warming temperature, i.e., whether the temperature of the hot water in the tank 1 is equal to or higher than the warming temperature (S22). If it is equal to or higher than the warming temperature (determined as YES in S22), it executes operation in the tank use mode. That is, while maintaining the switching state of the switching solenoid valve 16 so that the hot water in the tank 1 is supplied to the hot water supply heat exchanger 23 side, it does not ignite the hot water burner 22 and causes the hot water in the tank 1 to flow to the hot water outlet pipe 26 through the hot water supply heat exchanger 23. Then, the hot water in the tank 1 flows directly to the hot water outlet pipe 26 without being heated by the hot water supply heat exchanger 23 (S23). On the other hand, if the temperature of the hot water in tank 1 is below the warming temperature when operation of add hot water button 54 is detected, or if the temperature of the hot water in tank 1 drops below the warming temperature during hot water adding operation (determined as NO in S22), the hot water burner 22 is ignited while maintaining the switched state of switching solenoid valve 16, and the hot water in tank 1 is heated by hot water heat exchanger 23 and then discharged to hot water outlet pipe 26 (S24). Whether the hot water in tank 1 is directly discharged to hot water outlet pipe 26 or is heated by hot water heat exchanger 23 and then discharged to hot water outlet pipe 26, the temperature is adjusted by mixing it with tap water supplied via mixing pipe 30 in the same manner as above.

[0025] The controller 4 also opens the drop solenoid valve 48 of the drop pipe 47 to start dropping hot water into the bathtub 41. Thus, hot water supplied from the tank 1 flows from the outlet pipe 26 to the drop pipe 47, and is supplied to the bathtub 41 from the bath return pipe 42. Furthermore, the controller 4 determines that the addition of hot water has ended when the flow rate detected by the drop flow rate sensor 49 has reached a preset amount of hot water to be added (determines YES in S25), closes the drop solenoid valve 48, and stops the combustion of the hot water burner 22 if it was burning, thereby ending the addition of hot water to the bathtub 41, i.e., the hot water adding operation.

[0026] It is assumed that the user operates the hot water addition button 54 during the time period when the bathroom is in use. That is, even if the time period is assumed to be a time period when operation in the hot water supply mode, which does not use the hot water in the tank 1, is performed, when the hot water addition button 54 is operated, operation using the hot water in the tank 1 is performed. In addition, in the hot water addition operation, the hot water in the tank 1 is heated by the water heater 3, and although the temperature of the hot water in the tank 1 is lower than the insulation temperature, it is considered to be higher than the temperature of tap water. Therefore, if the hot water supply burner 22 is burned in the first combustion capacity range to heat the tap water to the set temperature when operating in the hot water supply mode, in order to heat the hot water in the tank 1 to the set temperature during the hot water addition operation, the hot water supply burner 22 may be burned in the second combustion capacity range that is lower than the first combustion capacity range.

[0027] Finally, the reheating operation will be explained. After filling the bath as described above, when the reheating button 53 on the remote control 5 is operated, the controller 4 executes the reheating operation to heat the hot water in the bathtub 41. That is, the circulation pump 43 is operated, the bath gas switching valve 38 is opened, the bath burner 24 is ignited, and the hot water in the bathtub 41 is circulated through the reheating circulation path 46 for reheating. When the temperature detected by the bath temperature thermistor 44 reaches the preset reheating temperature, the circulation pump 43 is stopped and the combustion of the bath burner 24 is stopped, and the reheating operation is terminated.

[0028] In the hot water supply system S configured as described above, when the add hot water button 54 is operated on the remote control 5, the controller 4 adds hot water in the tank 1 to the bathtub 41, even if it is during a bathroom usage time when operation in a hot water supply usage mode that does not use the hot water in the tank 1 is expected. In other words, since the hot water in the tank 1 is used for adding hot water, which uses less hot water than filling the bath, the hot water in the tank 1 is used, and therefore the hot water supply system S can be made to use the hot water in the tank 1 efficiently.

[0029] Furthermore, during times when the bathroom is in use and hot water is in high demand, the controller 4 executes hot water supply operation in a hot water supply usage mode that does not use the hot water in the tank 1 except when hot water is being added, so that the amount of hot water in the tank 1 is reduced or the temperature of the hot water in the tank 1 is reduced, which is called running out of hot water, and the hot water in the tank 1 can be used extremely efficiently. Furthermore, if hot water in the tank 1 runs out while it is being used and hot water needs to be switched to hot water supply using heating by the water heater 3, the water temperature will temporarily change significantly at the time of this switch, but because such an event is unlikely to occur, the hot water supply system S can be made to be less likely to cause discomfort to the user.

[0030] In addition, when the temperature of the hot water in the tank 1 is below the warming temperature when the operation of the hot water addition button 54 is detected, or when the temperature of the hot water in the tank 1 drops below the warming temperature during the hot water addition operation, the hot water in the tank 1 is heated by the water heater 3 before being supplied. At this time, although the temperature of the hot water in the tank 1 is below the warming temperature, it is considered to be higher than the temperature of tap water. Therefore, if the hot water burner 22 is burned in the first combustion capacity range when heating the tap water to the set temperature when operating in the hot water supply mode, in order to heat the hot water in the tank 1 to the set temperature during the hot water addition operation, the hot water burner 22 may be burned in the second combustion capacity range, which is lower than the first combustion capacity range. Therefore, the amount of carbon dioxide emissions associated with combustion in the water heater 3 can be reduced.

[0031] In addition, the hot water supply system of the present invention is not limited to the above-mentioned embodiment, and the overall configuration of the hot water supply system as well as the control over whether or not hot water in the tank can be used can be appropriately modified as needed.

[0032] For example, in the above embodiment, when a command to add hot water is given, the hot water in the tank is always used, but when a command to add hot water is given, the temperature of the hot water in the tank and the remaining amount of hot water in the tank are determined, and if the temperature of the hot water is above a predetermined temperature or the remaining amount of hot water is above a predetermined amount (predetermined conditions are met), the hot water in the tank is used, but if the temperature of the hot water is below the predetermined temperature or the remaining amount of hot water is less than a predetermined amount, the hot water in the tank is not used and tap water is heated to add hot water.

[0033] In addition, in the above embodiment, the reheating operation is performed by circulating the reheating circuit, but instead of such a reheating operation, a reheating operation may be performed in which hot water heated to a temperature higher than the set temperature is added to the bathtub. When performing such a reheating operation, similar to the above-mentioned hot water addition operation, when a reheating command is issued, the hot water in the tank may be used even during the bathroom usage time. Since such reheating is also considered to use less hot water than filling the bath, by configuring it to use the hot water in the tank, it is possible to achieve the effect of efficiently using the hot water in the tank, similar to the above embodiment.

[0034] Furthermore, in the above embodiment, the bathroom use time zone is set without taking into account the day of the week or whether it is a holiday, but the bathroom use time zone may be determined in association with the date. For example, the bathroom use time zone may not be set on Saturdays, Sundays, and holidays. It is also possible to set the bathroom use time zone separately for Saturdays, Sundays, and holidays and for weekdays.

[0035] Furthermore, in the above embodiment, the bathroom use time period is set in advance in the control means, but it is also possible not to set the bathroom use time period in advance. For example, a configuration is conceivable in which the control means stores the usage history of the hot water supply system and learns the bathroom use time period based on the usage history (for example, learning the time period when hot and cold water usage is high as the bathroom use time period), and automatically determines whether or not the bathroom use time period is based on the learning result. Another possible configuration is a configuration in which the control means determines that the bathroom use time period is a time period when a command to fill the bathtub or a command to add hot water is issued from the remote control, or a configuration in which the control means determines that the bathroom use time period is a time period when the bathroom priority button is operated on the remote control. Still another possible configuration is a configuration in which a human presence sensor is installed in the bathroom, and the control means determines that the bathroom use time period is a time period when the human presence sensor detects a person in the bathroom.

[0036] Furthermore, in the above embodiment, a remote control operated by the user is used as the command means, but the command means is not limited to a remote control. For example, in a device that is provided with a hot water volume detection sensor that detects the amount of hot water in the bathtub and allows the controller to detect the amount of hot water in the bathtub, the controller can be configured to automatically command the addition of hot water when the amount of hot water in the bathtub falls below a predetermined amount of hot water to be added, i.e., the controller can be configured to function as a command means.

[0037] In addition, the capacity of the tank is not limited to 20 L as in the above embodiment, but may be set appropriately between 10.00 L and 25.00 L. The heat exchanger of the water heater may be provided with both a primary heat exchanger for recovering sensible heat and a secondary heat exchanger for recovering latent heat. Furthermore, although the water heater of the above-described embodiment is equipped with a bath heating section, it is also possible to adopt a water heater without a bath heating section. [Explanation of symbols]

[0038] 1··Tank, 2··Heat pump, 3··Water heater, 4··Controller (control means), 5··Remote control (command means), 12··Relay pipe (first supply path, second supply path), 15··Direct water supply pipe (second supply path), 16··Switching solenoid valve, 20··Water heating section, 22··Water supply burner, 23··Water supply heat exchanger, 26··Outlet water pipe (first supply path, second supply path), 29··Water supply tap (point of use), 41··Bathtub (point of use), 54··Add hot water button, S··Water supply system.

Claims

1. A hot water supply system comprising: a tank for storing hot water; a heat pump for heating the hot water in the tank; a water heater for heating the supplied hot water by heat of combustion of a fuel gas; a plurality of supply paths for supplying the hot water to the points of use, including a first supply path for supplying the hot water in the tank to a predetermined point of use, and a second supply path for heating tap water in the water heater without passing through the tank and then supplying it to the point of use; and a control means for controlling the operation of the water heater and the selection of the supply paths, The location of use includes a bathroom and a bathtub, and the device is equipped with a time zone determination means for determining whether hot water is being supplied to the location of use during a bathroom usage time zone in which hot water is being used in the bathroom, and a command means for issuing a command to the control means, When the control means determines that hot water is to be supplied during the bathroom usage time period, the control means does not use the hot water stored in the tank, but supplies hot water to the location of use through the second supply path, A hot water supply system characterized in that when the command means commands hot water to be added to the bathtub, hot water is added to the bathtub via the first supply path even during the bathroom usage time period.

2. A hot water supply system comprising: a tank for storing hot water; a heat pump for heating the hot water in the tank; a water heater for heating the supplied hot water by heat of combustion of a fuel gas; a plurality of supply paths for supplying the hot water to the points of use, including a first supply path for supplying the hot water in the tank to a predetermined point of use, and a second supply path for heating tap water in the water heater without passing through the tank and then supplying it to the point of use; and a control means for controlling the operation of the water heater and the selection of the supply paths, The location of use includes a bathroom and a bathtub, and the device is equipped with a time zone determination means for determining whether hot water is being supplied to the location of use during a bathroom usage time zone in which hot water is being used in the bathroom, and a command means for issuing a command to the control means, When the control means determines that hot water is to be supplied during the bathroom usage time period, the control means does not use the hot water stored in the tank, but supplies hot water to the location of use through the second supply path, A hot water supply system characterized in that when the command means commands the addition of hot water to the bathtub and predetermined conditions are satisfied, hot water is added to the bathtub via the first supply path even during the bathroom usage time period.

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