Hot water system

Abstract

To provide a hot water supply system that can discharge hot water at a stable hot water supply temperature from a hot water discharge terminal.SOLUTION: A hot water supply system comprises a heating heat source 501, a hot water storage tank 6, a heating going pipe 40, a heating returning pipe 44, a heating circulation pump 51, and a hot water supply going pipe 71. The heating returning pipe 44 and the hot water supply going pipe 71 are connected to an upper part of the hot water storage tank 6. When the time of a non-operation state of heating heat sources 501 and 502 and heating circulation pumps 51 and 52 becomes equal to or longer than predetermined non-operation determination time, the heating circulation pumps 51 and 52 are operated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot water supply system, and more particularly to a hot water supply system that performs pipe heat retention control to retain the heat of a heating return pipe that returns hot water from a heating heat source to a hot water storage tank. [Background technology]

[0002] A hot water supply system has been known in the past that has a heating heat source, a hot water storage tank, piping connecting them, and a circulation pump installed on the piping, and that stores hot water heated by the heating heat source in the hot water storage tank and supplies the stored hot water to a hot water outlet terminal. In this type of hot water supply system, in order to prevent the temperature stratification of the hot water in the hot water storage tank from collapsing, a heating supply pipe that sends the hot water in the hot water storage tank to the heating heat source is connected to the bottom of the hot water storage tank, and a heating return pipe that returns the hot water dispensed from the heating heat source to the hot water storage tank and a hot water supply supply pipe that supplies the hot water from the hot water storage tank to the hot water outlet terminal are connected to the top of the hot water storage tank (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 2607249 Summary of the Invention [Problem to be solved by the invention]

[0004] Hot water supply systems used in facilities such as hair salons must stably supply a large amount of hot water at a predetermined temperature to multiple hot water outlet terminals such as showers and faucets. Therefore, when hot water is being used at the hot water outlet terminals, water supplied from a water supply source may be heated by a heating heat source, and the heated water may be flowed into a hot water storage tank by a circulation pump, and the hot water may be supplied from the hot water storage tank to the hot water outlet terminals.

[0005] However, in the hot water supply system described above, when the hot water in the hot water storage tank reaches a predetermined hot water temperature setting, the operation of the heating heat source and the circulation pump is stopped. Natural heat dissipation cools the piping connecting the heating heat source and the hot water storage tank. If the heating heat source is located outside the facility or if the outdoor temperature is low in winter, the temperature of the hot water stagnating in the piping drops significantly. Therefore, when hot water is used at the hot water outlet terminal and the operation of the heating heat source and the circulation pump is resumed, low-temperature hot water flows into the hot water storage tank from the heating return pipe connected to the top of the hot water storage tank. Since the hot water supply pipe is connected to the top of the hot water storage tank near the heating return pipe, the low-temperature hot water flowing into the hot water storage tank from the heating return pipe lowers the temperature of the hot water supplied from the hot water storage tank to the hot water supply pipe. As a result, hot water lower than the predetermined hot water temperature is supplied to the hot water outlet terminal, resulting in a deterioration of temperature control performance.

[0006] The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a hot water supply system that can dispense hot water at a stable hot water temperature from a hot water dispensing terminal. [Means for solving the problem]

[0007] According to the present invention, A heating source; a hot water storage tank for storing hot water heated by a heating heat source; A heating supply pipe connected to the bottom of the hot water storage tank and sending hot water from the hot water storage tank to the heating heat source; A heating return pipe connected to the top of the hot water storage tank and returning hot water from the heating heat source to the hot water storage tank; a heating circulation pump that circulates hot water between the heating heat source and the hot water storage tank; A hot water supply pipe connected to the top of the hot water storage tank and supplying hot water from the hot water storage tank to the hot water outlet terminal; a control device that executes piping heat retention control to keep the heating return pipe warm, The hot water supply system has a control configuration in which the control device operates the heating circulation pump when the heating heat source and the heating circulation pump remain in an inoperative state for a predetermined inoperative determination time or longer.

[0008] According to the hot water supply system, when the heating heat source and heating circulation pump are not in operation for a predetermined period of time or longer, the heating circulation pump is activated, so that the hot water in the heating return pipe, whose temperature has dropped due to natural heat dissipation, can be replaced with hot water stored in the hot water storage tank, thereby supplying hot water at a stable hot water temperature to the hot water supply terminal.

[0009] Preferably, in the hot water supply system, When the heating heat source and heating circulation pump remain in an inoperative state for longer than the inoperative judgment time and the control device operates the heating circulation pump, if the temperature of the hot water in the hot water storage tank is equal to or higher than a predetermined heat retention judgment temperature near a predetermined hot water storage set temperature, the control device continues operating the heating circulation pump for a predetermined heat retention operation time without operating the heating heat source.

[0010] According to the above-mentioned hot water supply system, when the heating heat source and heating circulation pump are in an inoperative state for longer than the inoperative judgment time and the temperature of the hot water in the hot water storage tank is equal to or higher than a predetermined heat retention judgment temperature near the predetermined hot water storage set temperature, the heating circulation pump continues to operate for the predetermined heat retention operation time without operating the heating heat source.Therefore, when the temperature of the hot water in the hot water storage tank is high, the hot water in the heating return pipe can be replaced with the hot water in the hot water storage tank in an energy-saving manner.

[0011] Preferably, in the hot water supply system, When the heating heat source and heating circulation pump remain in an inoperative state for longer than the inoperative judgment time and the control device activates the heating circulation pump, if the temperature of the hot water in the hot water storage tank is below a predetermined heat retention judgment temperature near a predetermined hot water storage setting temperature, the control device continues to operate the heating circulation pump and activates the heating heat source.

[0012] According to the above-mentioned hot water supply system, when the heating heat source and heating circulation pump remain in an inoperative state for longer than the inoperative judgment time and the heating circulation pump is operated, if the temperature of the hot water in the hot water storage tank is below the heat retention judgment temperature close to the hot water storage set temperature, the heating circulation pump continues to operate and the heating heat source is operated, so that the hot water in the heating return pipe can be replaced with hot water heated by the heating heat source.

[0013] Preferably, in the hot water supply system, The control device sets the outlet temperature of the hot water heated by the heating heat source to a predetermined outlet temperature for keeping the water warm, which is higher than the set hot water temperature, and operates the heating heat source.

[0014] According to the hot water supply system, the outlet temperature of the hot water heated by the heating heat source is set to a predetermined warm water outlet temperature higher than the hot water storage temperature setting, and the heating heat source is operated. Therefore, even if the temperature of the hot water in the hot water storage tank is close to the hot water storage temperature setting, the hot water discharged from the hot water storage tank can be heated by the heating heat source, and the hot water in the heating return pipe can be reliably replaced with hot water heated by the heating heat source. Furthermore, according to the hot water supply system, the temperature of the hot water in the hot water storage tank is higher than the hot water storage temperature setting, so the temperature of the hot water in the hot water storage tank is likely to be maintained higher than close to the hot water storage temperature setting. Therefore, the next time pipe insulation control is performed, the hot water in the heating return pipe can be replaced with hot water in the hot water storage tank by operating the heating circulation pump without operating the heating heat source.

[0015] Preferably, in the hot water supply system, When hot water is discharged from the heating heat source at a hot water outlet temperature for keeping the temperature of the hot water, the control device stops the heating heat source and the heating circulation pump when the temperature of the hot water flowing from the heating return pipe into the hot water storage tank reaches or exceeds a predetermined first heat retention stop temperature that is higher than the heat retention judgment temperature, or when the temperature of the hot water in the hot water storage tank reaches or exceeds a predetermined second heat retention stop temperature that is higher than the hot water storage set temperature.

[0016] According to the hot water supply system, when hot water is dispensed from the heating heat source at the warm water outlet temperature, if the temperature of the hot water flowing from the heating return pipe into the hot water storage tank reaches or exceeds a predetermined first warm water stop temperature higher than the warm water determination temperature, or if the temperature of the hot water in the hot water storage tank reaches or exceeds a predetermined second warm water stop temperature higher than the hot water storage set temperature, the heating heat source and heating circulation pump are stopped, preventing the heating heat source from heating the hot water more than necessary and preventing the hot water temperature in the hot water storage tank from rising more than necessary. This allows hot water at a stable hot water supply temperature to be supplied to the hot water dispensing terminal while saving energy.

[0017] Preferably, in the hot water supply system, The control device sets the non-operation determination time in accordance with the outside air temperature.

[0018] According to the hot water supply system, the non-operation determination time can be set more appropriately depending on the heat radiation state of the pipes. [Effects of the Invention]

[0019] As described above, according to the present invention, hot water can be dispensed from the hot water dispensing terminal at a stable hot water temperature, and a hot water supply system with excellent temperature control performance can be provided, thereby improving user convenience and comfort. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram showing an example of a hot water supply system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing a control operation in the pipe insulation control of the hot water supply system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a hot water supply system according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing an example of a hot water supply system according to this embodiment. This hot water supply system can be used in commercial facilities such as hair salons. The hot water supply system includes a hot water pressurized tank unit 1 and a heat source unit 500. The hot water pressurized tank unit 1 supplies cold water and hot water to multiple hot water outlet terminals 400, such as showers and faucets. The heat source unit 500 includes a first gas heat source unit 501 and a second gas heat source unit 502, which are heating heat sources. The hot water pressurized tank unit 1 includes a water supply tank 2 that receives primary water supply and a hot water storage tank 6 that stores hot water heated by the first and second gas heat source units 501 and 502. The hot water supply system may include one or three or more gas heat source units as a heating heat source, and may use a heat pump, electric heater, or the like instead of the gas heat source units.

[0022] The first and second gas heat source units 501, 502 are gas water heaters, and although not shown, have a heating unit in the housing that has a gas burner, a heat exchanger, etc. The first and second gas heat source units 501, 502 and the hot water storage tank 6 are connected by a heating circulation circuit consisting of a heating supply pipe 40 that sends hot water from the hot water storage tank 6 and water from the water supply tank 2 to the first and second gas heat source units 501, 502, and a heating return pipe 44 that returns the hot water heated in the first and second gas heat source units 501, 502 to the hot water storage tank 6.

[0023] One end of the heating supply pipe 40 is connected to the bottom of the hot water storage tank 6, and the other end is branched into a first heating supply pipe 41 and a second heating supply pipe 42 so as to be connected to a first gas heat source unit 501 and a second gas heat source unit 502. The heating return pipe 44 is formed by joining a first heating return pipe 45 and a second heating return pipe 46, each of which has one end connected to the gas heat source units 501, 502, and the other end is connected to the top of the hot water storage tank 6. A heating supply temperature sensor 50 is disposed in the heating supply pipe 40 upstream of the branch point of the first and second heating supply pipes 41, 42 and downstream of the junction with the water supply pipe 3, which will be described later.

[0024] A first heating circulation pump 51 and a second heating circulation pump 52 are provided in the first and second heating supply pipes 41 and 42, respectively, and check valves 53 and 54 are provided downstream of the first and second heating circulation pumps 51 and 52. Therefore, by operating the first and second heating circulation pumps 51 and 52 and the first and second gas heat source units 501 and 502, hot water heated by the first and second gas heat source units 501 and 502 is stored in the hot water storage tank 6. The first and second heating circulation pumps 51 and 52 are connected to a hot water supply control device C, and their operation, stop, and rotation speed are controlled by control signals from the hot water supply control device C. In addition, the heat source unit controllers C1 and C2 of the first and second gas heat source units 501 and 502 are connected to the hot water supply control device C, and the operation of the first and second gas heat source units 501 and 502 is controlled by control signals from the hot water supply control device C. The detection signal of the detected temperature detected by the heating supply temperature sensor 50 is output to the hot water control device C, and detection signals such as the detected temperature detected by various sensors not shown in the figure arranged in the gas heat source machines 501 and 502 are output to the heat source machine control devices C1 and C2.

[0025] An under-tank temperature sensor 55 for detecting the temperature of the hot water supplied from the hot water storage tank 6 to the heating supply pipe 40, and a valve 56 are installed upstream of the junction with the water supply pipe 3 in the heating supply pipe 40 connected to the lower part of the hot water storage tank 6. A detection signal of the detected temperature detected by the under-tank temperature sensor 55 is output to the hot water supply control device C. The valve 56 can be opened and closed manually, but it may also be configured so that its opening and closing is controlled by a control signal from the hot water supply control device C.

[0026] The hot water storage tank 6 is made of a corrosion-resistant metal (e.g., stainless steel), and its periphery is covered with a heat insulating material (not shown). The capacity of the hot water storage tank 6 in this embodiment is, for example, 50 L. The lower part of the hot water storage tank 6 is connected to the previously described heating supply pipe 40 and a hot water supply return pipe 72 that returns hot water from the hot water outlet terminal 400 (described later). The upper part of the hot water storage tank 6 is connected to the previously described heating return pipe 44 and a hot water supply supply pipe 71 that connects to the hot water outlet terminal 400 (described later). The hot water storage tank 6 is equipped with a first hot water temperature sensor 61, a second hot water temperature sensor 62, and a third hot water temperature sensor 63, which detect the temperature of the hot water inside, attached in this order from top to bottom at a predetermined interval. The hot water supply pressurization tank unit 1 also includes an outside air temperature sensor 80 below the hot water storage tank 6 for detecting the outside air temperature. The temperature signals detected by these temperature sensors 61, 62, 63, and 80 are output to the hot water supply control device C.

[0027] An automatic air vent valve 57 for venting air from the hot water storage tank 6 and a heated return temperature sensor 58 for detecting the temperature of the hot water flowing into the hot water storage tank 6 are installed in the heated return pipe 44 connected to the top of the hot water storage tank 6. A detection signal of the detected temperature detected by the heated return temperature sensor 58 is output to the hot water supply control device C.

[0028] A substantially rectangular box-shaped water supply tank 2 is disposed above the hot water storage tank 6 to supply water to the gas heat source units 501 and 502, the hot water storage tank 6, and the hot water outlet terminal 400. In this embodiment, the capacity of the water supply tank 2 is, for example, 45 L. A primary water supply pipe 10, through which city water flows, is connected to the top of the water supply tank 2, and a water supply pipe 3 is connected to the bottom of the water supply tank 2. The primary water supply pipe 10 branches into two pipes, a first primary water supply pipe 11 and a second primary water supply pipe 12, which are connected to the water supply tank 2. The first and second primary water supply pipes 11 and 12 are respectively provided with, in order from upstream, a first governor 13, a second governor 14, a first water supply solenoid valve 15, and a second water supply solenoid valve 16. The first and second water supply solenoid valves 15 and 16 are connected to the hot water supply control device C and are controlled to open and close by control signals from the hot water supply control device C. In this way, by connecting multiple primary water supply pipes 11, 12 to the water supply tank 2, pressure loss can be reduced and water can be supplied to the water supply tank 2 in a short time. Although not shown, a portion of the water supply tank 2 is open to the atmosphere.

[0029] The water supply tank 2 has an opening in one side wall below the connection ports for the first and second primary water supply pipes 11, 12 and above the connection port for the water supply pipe 3. An overflow pipe 200 is connected to the opening in this side wall. On the other side wall of the water supply tank 2, an overfloat sensor 22, a Hi float sensor 23, a Low float sensor 24, and a low water level float sensor 25 are arranged in this order from top to bottom at predetermined intervals to detect the water level in the water supply tank 2. Although not shown, a substantially U-shaped trap pipe (not shown) is arranged in the water supply tank 2. One end of the trap pipe 2 is connected to the overflow pipe 200, and the other end is at approximately the same height as the overfloat sensor 22 and opens upward. Therefore, excess water is discharged to the outside through the trap pipe and the overflow pipe 200. Water level detection signals detected by the float sensors 22, 23, 24, and 25 are output to the hot water supply control device C.

[0030] One end of the water supply pipe 3 is connected to the bottom of the water supply tank 2, and branches upstream into a first water supply pipe 31 and a second water supply pipe 32 so that water flows in parallel. A water supply booster pump 37 is installed upstream of the branch point between the first water supply pipe 31 and the second water supply pipe 32. The water supply booster pump 37 is connected to the hot water supply control device C, and its operation, stoppage, and rotation speed are controlled by control signals from the hot water supply control device C.

[0031] The first water supply pipe 31 is provided with, from upstream to downstream, a check valve 33 and a pressure sensor (pressure detection means) 35 for detecting water pressure. The second water supply pipe 32 is provided with, from upstream to downstream, a check valve 34 and a water volume sensor (water volume detection means) 36 for detecting water flow rate. While it is possible to incorporate a pressure sensor and a water volume sensor in a single water passage without providing parallel water passages, pressure loss can be reduced by forming water passages so that water flows in parallel and incorporating a pressure sensor and a water volume sensor in each passage. Although the water flow rate differs in each passage, if the pressure loss is known, the water flow rate of the entire water supply pipe 3 can be calculated from the water flow rate detected by the water volume sensor 36. The detection signals of the detected pressure detected by the pressure sensor 35 and the detected flow rate detected by the water volume sensor 36 are output to the hot water supply control device C.

[0032] The first water supply pipe 31 and the second water supply pipe 32 join at a junction downstream of the pressure sensor 35 and the water volume sensor 36, and the other end of the water supply pipe 3 is connected to a junction with a heating supply pipe 40 connected to the bottom of the hot water storage tank 6. The water supply pipe 3 also branches into a water supply pipe 38 connected to the hot water outlet terminal 400 downstream of the junction of the first and second water supply pipes 31 and 32. Therefore, in this embodiment, by operating the water supply pressure pump 37, water is supplied to the hot water storage tank 6, the gas heat source units 501 and 502, and the hot water outlet terminal 400, and the water supply pipe 3, including the first and second water supply pipes 31 and 32 and the water supply pipe 38, constitutes a water supply circuit. The water supply pipe 38 branches into multiple parts depending on the number of showers and faucets in the hot water outlet terminal 400. A check valve 39 is provided in the water supply pipe 3 downstream of the branch point of the water supply outflow pipe 38.

[0033] One end of the hot water return pipe 72 is connected to the bottom of the hot water storage tank 6, and the other end is connected to the hot water supply pipe 71 at the hot water outlet terminal 400. An instant hot water circulation pump 73 is installed in the hot water return pipe 72, and an instant hot water return temperature sensor 74 and a check valve 75 are installed downstream of the instant hot water circulation pump 73. Therefore, in this embodiment, by operating the instant hot water circulation pump 73, hot water is circulated between the hot water storage tank 6 and the hot water outlet terminal 400, and the hot water supply pipe 71 and the hot water return pipe 72 connecting the hot water storage tank 6 and the hot water outlet terminal 400 constitute an instant hot water circulation circuit.

[0034] The pipe insulation control in the hot water supply system of this embodiment will be described later, but to summarize the main operational control, when the hot water tap at the hot water outlet terminal 400 is opened and the water supply pressure pump 37 starts operating, if the temperature of the hot water detected by the third hot water storage temperature sensor 63 is higher than the predetermined hot water storage start temperature, water is supplied from the water supply tank 2 to the hot water storage tank 6 via the water supply pipe 3 and the heating supply pipe 40 below the tank connected to the hot water storage tank 6 without operating the first and second heating circulation pumps 51, 52, and the hot water in the hot water storage tank 6 is supplied to the hot water outlet terminal 400 via the hot water supply supply pipe 71. Furthermore, as the temperature of the hot water decreases due to the supply of water into the hot water storage tank 6, when the temperature of the hot water detected by the third hot water storage temperature sensor 63 falls below the hot water storage start temperature, the first and second heating circulation pumps 51, 52 begin operating, hot water is supplied from the bottom of the hot water storage tank 6 to the heating supply pipe 40, the water from the water supply tank 2 and the hot water from the hot water storage tank 6 are mixed and supplied to the first and second gas heat source units 501, 502. The hot water heated to a predetermined hot water outlet temperature in the first and second gas heat source units 501, 502 is then returned to the hot water storage tank 6 via the heating return pipe 44. Furthermore, hot water is sent from the hot water storage tank 6 to the hot water supply supply pipe 71, and hot water is supplied to the hot water outlet terminal 400 via the hot water supply supply pipe 71 (hot water outlet control).

[0035] Furthermore, when all hot water outlet terminals 400 are closed and the temperature of the hot water detected by the third hot water storage temperature sensor 63 falls below the hot water storage start temperature, the first and second heating circulation pumps 51, 52 begin to operate, the hot water in the hot water storage tank 6 is supplied to the first and second gas heat source units 501, 502, and the hot water heated to a predetermined hot water outlet temperature in the first and second gas heat source units 501, 502 is returned to the hot water storage tank 6, thereby maintaining the temperature of the hot water in the hot water storage tank 6 (hot water storage control).

[0036] In addition, when all hot water outlet terminals 400 are closed and a predetermined instant hot water start time has elapsed and the temperature of the hot water stagnating in the hot water supply pipe 71 and the hot water return pipe 72 has dropped, the instant hot water circulation pump 73 begins to operate, and hot water is circulated between the hot water storage tank 6 and the hot water outlet terminals 400 via the hot water supply pipe 71 and the hot water return pipe 72 (instant hot water control).

[0037] The first and second heating circulation pumps 51, 52 are operated simultaneously or individually depending on the amount of hot water used at the hot water outlet terminal 400 and the setting of the instant hot water control, and accordingly the first and second gas heat source units 501, 502 are also operated simultaneously or individually.

[0038] The hot water supply system includes a hot water supply control device C provided in the hot water supply pressurized tank unit 1, heat source machine control devices C1 and C2 provided in the first and second gas heat source machines 501 and 502, and a remote control R for a user to perform operations related to the operation of the hot water supply system. The hot water supply control device C and the heat source machine control devices C1 and C2 are connected to each other by wire or wirelessly so that they can communicate with each other, and the hot water supply control device C and the remote control R are connected to each other by wire or wirelessly so that they can communicate with each other.

[0039] The remote control R is a terminal device configured to instruct the hot water supply control device C on operational information such as turning the power of the hot water supply system on and off, the hot water storage temperature setting for the hot water in the hot water storage tank 6 (the hot water outlet temperature of the hot water dispensed from the first and second gas heat source units 501, 502 in hot water outlet control and hot water storage control), and setting the water pressure mode in response to the user's operation of an operation switch (not shown). The remote control R is equipped with a display that displays various information about the hot water supply system. Note that a mobile terminal such as a smartphone or tablet terminal connected to the hot water supply control device C so as to be able to communicate with it can be used instead of or together with the remote control R.

[0040] The hot water supply control device C and the heat source machine control devices C1 and C2 each consist of one or more electronic circuit units including a CPU, ROM, RAM, interface circuitry, etc. The memory stores various operation programs and various data such as setting values ​​for executing the operation programs.

[0041] The hot water supply control device C receives detection signals from the various sensors (temperature sensors 50, 55, 58, 61, 62, 63, 74, 80, pressure sensor 35, water volume sensor 36, float sensors 22-25) described above, and also receives operation information from the remote controller R. The heat source machine control devices C1, C2 also receive detection signals from various sensors (not shown) provided in the first and second gas heat source machines 501, 502, and output control signals to the hot water supply control device C. The hot water supply control device C controls the operation of the gas heat source machines 501, 502, the various pumps 37, 51, 52, 73, the water supply solenoid valves 15, 16, and the like, thereby controlling the operation of the entire hot water supply system. Therefore, in this embodiment, the hot water supply control device C and the heat source machine control devices C1, C2 constitute the control devices of the hot water system. It is noted that the operation of the entire hot water supply system may be controlled by a single control device, without providing the heat source machine control devices C1, C2.

[0042] Next, the control operation of the pipe insulation control in the hot water supply system of this embodiment will be described with reference to Figure 2. When hot water is used at the hot water supply terminal 400, the operation of the gas heat source units 501, 502 and the heating circulation pumps 51, 52 is resumed by the hot water discharge control described above. At this time, the flow rate of hot water flowing through the heating circulation circuit becomes relatively high (for example, approximately 12 L / min). Therefore, if the hot water temperature in the heating return pipe 44 drops, a large amount of low-temperature hot water flows into the upper part of the hot water storage tank 6, causing a drop in the temperature of the hot water supplied from the hot water storage tank 6 to the hot water supply pipe 71, and also deteriorating the temperature control performance of the hot water dispensed at the hot water dispense terminal 400. Therefore, the following pipe insulation control is executed to stabilize the temperature of the hot water dispensed at the hot water dispense terminal 400.

[0043] When the remote control R is in an on state, if the temperature detected by the third hot water storage temperature sensor 63 is higher than a predetermined hot water storage start temperature (e.g., 53°C) and the execution condition for the hot water storage control is not established (Yes in step S1), the outdoor air temperature Ta detected by the outdoor air temperature sensor 80 is acquired (step S2). If the execution condition for the hot water storage control is established (No in step S1), the hot water heated by the gas heat source units 501, 502 described above is circulated to the heating return pipe 44 (step S20), thereby raising the temperature of the hot water in the heating return pipe 44. Furthermore, under conditions where the hot water storage control is not executed, the temperature of the hot water in the hot water storage tank 6 is higher than the hot water storage start temperature. Therefore, as described below, if the temperature of the hot water in the hot water storage tank 6 is equal to or higher than the insulation determination temperature, the first gas heat source unit 501 is not operated, and only the first heating circulation pump 51 is operated to circulate the hot water in the hot water storage tank 6 and efficiently replace the hot water in the heating return pipe 44 with the hot water in the hot water storage tank 6.

[0044] Next, the operation of the first and second heating circulation pumps 51, 52 is determined to determine whether the first and second gas heat source units 501, 502 and the first and second heating circulation pumps 51, 52 are in an inactive state (step S3). If the heating circulation pumps 51, 52 are in operation (No in step S3), the process returns to determining whether the conditions for executing hot water storage control are not met (step S1). On the other hand, if neither the first nor second heating circulation pumps 51, 52 are in operation (Yes in step S3), the process sets an inactive determination time t1 (minutes) according to the outside air temperature Ta detected by the outside air temperature sensor 80, according to the following equation (1), and starts a timer (step S4). Non-operation judgment time t1 = a × Ta + b (1)

[0045] In equation (1), a and b are constants determined by the set temperature and piping length of the hot water in heating return pipe 44 after replacement, and are values ​​found by experiment. For example, in the hot water supply system of this embodiment, if the set temperature of the hot water in heating return pipe 44 after replacement is 55°C and the piping length of heating return pipe 44 is 18m, a is 0.2 and b is 20. The non-operation determination time t1 can be set appropriately depending on the configuration of the hot water supply system.

[0046] When the non-operating state in which neither first nor second gas heat source units 501, 502 are operated and neither first nor second heating circulation pumps 51, 52 are operated continues for a period of time equal to or longer than non-operating determination time t1 (Yes in step S5), operation of first heating circulation pump 51 is started at a predetermined rotation speed (step S6). On the other hand, if the non-operating state of first and second heating circulation pumps 51, 52 is shorter than non-operating determination time t1 (No in step S5), the process returns to determining whether the conditions for executing hot water storage control are not met (step S1). Note that in the pipe insulation control of this embodiment, only first heating circulation pump 51 is operated; however, if the hot water supply system has multiple heating circulation pumps, two or more heating circulation pumps may be operated, or different heating circulation pumps may be operated in sequence.

[0047] Next, when the first heating circulation pump 51 is operated, it is determined whether the temperature of the hot water in the hot water storage tank 6 detected by the first hot water temperature sensor 61 is less than a predetermined heat retention judgment temperature T2 (e.g., 61°C) that is slightly higher than a predetermined hot water setting temperature T1 (e.g., 60°C), which is the target value for hot water storage control (step S7). In this way, when determining the temperature of the hot water in the hot water storage tank 6, if the heat retention judgment temperature T2 is set to a value close to the hot water setting temperature T1 that is slightly higher than the hot water setting temperature T1 (e.g., the hot water setting temperature T1 + 5°C, preferably the hot water setting temperature T1 + 2°C), it is possible to suppress a decrease in the temperature of the hot water in the heating return pipe 44 after replacement. For this reason, the heat retention judgment temperature T2 may be set to a value close to the hot water setting temperature T1 that is slightly lower than the hot water setting temperature T1 (e.g., the hot water setting temperature T1 - 5°C, preferably the hot water setting temperature T1 - 2°C), but is preferably set to a value slightly higher than the hot water setting temperature T1. The reason why the temperature of the hot water in the hot water storage tank 6 may become higher than the set hot water storage temperature T1 is because a warm-keeping outlet hot water temperature Th, which will be described later, is set higher than the set hot water storage temperature T1.

[0048] If the temperature of the hot water in the hot water storage tank 6 is equal to or higher than the heat retention judgment temperature T2 (No in step S7), a timer is started and the operation of the first heating circulation pump 51 continues for a predetermined heat retention operation time t2 (for example, 2 minutes). After the heat retention operation time t2 has elapsed, the first heating circulation pump 51 is stopped (steps S8 and S12). This allows the hot water in the heating return pipe 44 to be replaced with the hot water in the hot water storage tank 6.

[0049] On the other hand, if the temperature of the hot water in the hot water storage tank 6 is below the heat retention judgment temperature T2 (Yes in step S7), the outlet hot water temperature is set to a predetermined heat retention outlet hot water temperature Th (for example, 70°C) that is higher than the hot water storage setting temperature T1 for hot water storage control, and the first gas heat source unit 501 is operated (step S9). If the outlet hot water temperature of the first gas heat source unit 501 remains set to the same as the hot water storage setting temperature T1, when the temperature of the hot water in the hot water storage tank 6 is lower than the heat retention judgment temperature T2 but close to the hot water storage setting temperature T1, the temperature difference between the hot water storage setting temperature T1 and the temperature of the hot water sent from the hot water storage tank 6 that is close to the hot water storage setting temperature T1 becomes small, and there is a possibility that the hot water will not be heated by the first gas heat source unit 501. However, by setting the hot water outlet temperature of the first gas heat source unit 501 to a hot water outlet temperature Th for heat retention which is higher than the hot water storage setting temperature T1, even if the temperature of the hot water in the hot water storage tank 6 is close to the hot water storage setting temperature T1, the hot water discharged from the hot water storage tank 6 is heated by the first gas heat source unit 501, so that the hot water in the heating return pipe 44 can be reliably replaced with hot water heated by the first gas heat source unit 501.

[0050] When the first heating circulation pump 51 is operated as described above, hot water at the heat retention outlet temperature Th is discharged from the first gas heat source unit 501 and the hot water is circulated between the first gas heat source unit 501 and the hot water storage tank 6, and it is determined whether the temperature of the hot water detected by the heating return temperature sensor 58 installed in the heating return pipe 44 connected to the top of the hot water storage tank 6 has risen to a predetermined first heat retention stop temperature Ti (e.g., 67°C) higher than the heat retention judgment temperature T2, or whether the temperature of the hot water detected by the first hot water storage temperature sensor 61 has risen to a predetermined second heat retention stop temperature Tj (e.g., 65°C) higher than the hot water storage set temperature T1 (steps S10 to S11). In this way, by operating the first gas heat source unit 501 until the temperature of the hot water in the heating return pipe 44 reaches or exceeds the first heat retention stop temperature Ti, which is higher than the heat retention judgment temperature T2, or until the temperature of the hot water in the hot water storage tank 6 reaches or exceeds the second heat retention stop temperature Tj, which is higher than the hot water setting temperature T1, hot water heated by the first gas heat source unit 501 is circulated for a certain period of time even if the temperature of the hot water in the hot water storage tank 6 is close to the hot water setting temperature T1, so that the hot water in the heating return pipe 44 can be reliably replaced with hot water heated by the first gas heat source unit 501. Furthermore, if the temperature of the hot water in the hot water storage tank 6 reaches or exceeds the second heat retention stop temperature Tj, which is higher than the hot water setting temperature T1, hot water at a temperature equal to or higher than the hot water setting temperature T1 is stored in the upper part of the hot water storage tank 6, so that in the next pipe heat retention control, the temperature of the hot water detected by the first hot water storage temperature sensor 61 is likely to be maintained at or above the heat retention judgment temperature T2. As a result, the hot water in the heat return pipe 44 can be replaced with the hot water stored in the hot water storage tank 6 by operating only the first heat circulation pump 51.

[0051] If the temperature of the hot water detected by the heating return temperature sensor 58 is equal to or higher than the first heat retention stop temperature Ti (Yes in step S10), or if the temperature of the hot water detected by the first hot water storage temperature sensor 61 is equal to or higher than the second heat retention stop temperature Tj (Yes in step S11), the first heating circulation pump 51 is stopped (step S12) and the process returns to determining whether the conditions for executing the hot water storage control are not met (step S1).

[0052] As described above, according to this embodiment, when heating circulation pumps 51, 52 and gas heat source units 501, 502 remain in an inoperative state for a predetermined inoperative determination time or longer, first heating circulation pump 51 is operated, so that the hot water in heating return pipe 44, whose temperature has dropped due to natural heat dissipation, can be replaced with hot water stored in hot water storage tank 6. As a result, even if hot water use is started at hot water dispensing terminal 400 at any timing, hot water at a stable hot water supply temperature can be supplied to the hot water dispensing terminal.

[0053] Furthermore, according to this embodiment, when the non-operating state of the heating circulation pumps 51, 52 and the gas heat source units 501, 502 has been in operation for longer than the non-operating judgment time and the first heating circulation pump 51 is operated, if the temperature of the hot water in the hot water storage tank 6 is equal to or higher than a predetermined heat retention judgment temperature near the predetermined hot water storage set temperature, the first heating circulation pump 51 continues to operate for the predetermined heat retention operation time without operating the gas heat source units 501, 502.Therefore, when the temperature of the hot water in the hot water storage tank 6 is high, the hot water in the heating return pipe 44 can be replaced with the hot water in the hot water storage tank 6 in an energy-saving manner.

[0054] Furthermore, according to this embodiment, when the non-operating state of the heating circulation pumps 51, 52 and the gas heat source units 501, 502 reaches or exceeds a predetermined non-operating judgment time, and the first heating circulation pump 51 is operated, if the temperature of the hot water in the hot water storage tank 6 is below a heat retention judgment temperature close to the hot water storage set temperature, the first heating circulation pump 51 continues to operate and the first gas heat source unit 501 is operated, so that the hot water in the heating return pipe 44 can be replaced with hot water heated by the first gas heat source unit 501.

[0055] Furthermore, according to this embodiment, the outlet temperature of the hot water heated by the first gas heat source unit 501 is set to a warm-keeping outlet temperature higher than the hot water storage setting temperature, and the first gas heat source unit 501 is operated. Therefore, even if the temperature of the hot water in the hot water storage tank 6 is close to the hot water storage setting temperature, the first gas heat source unit 501 can heat the hot water delivered from the hot water storage tank 6, and the hot water in the heating return pipe 44 can be reliably replaced with hot water heated by the first gas heat source unit 501. Furthermore, because the temperature of the hot water in the hot water storage tank 6 is higher than the hot water storage setting temperature, the temperature of the hot water in the hot water storage tank 6 is likely to be maintained higher than close to the hot water storage setting temperature. Therefore, the next time pipe insulation control is performed, the hot water in the heating return pipe 44 can be replaced with hot water stored in the hot water storage tank 6 by operating the first or second heating circulation pump 51, 52 without operating the gas heat source units 501, 502.

[0056] Furthermore, according to this embodiment, when hot water is dispensed from first gas heat source unit 501 at the warm water outlet temperature, if the temperature of the hot water flowing from heating return pipe 44 into hot water storage tank 6 exceeds a predetermined first warm water stop temperature higher than the warm water determination temperature, or if the temperature of the hot water in hot water storage tank 6 exceeds a predetermined second warm water stop temperature higher than the hot water storage set temperature, first heating circulation pump 51 and first gas heat source unit 501 are stopped. This prevents the first gas heat source unit 501 from heating the hot water more than necessary when replacing the hot water in heating return pipe 44 with hot water heated by first gas heat source unit 501, and prevents the temperature of the hot water in hot water storage tank 6 from rising more than necessary. This allows hot water at a stable hot water supply temperature to be supplied to the hot water dispensing terminal in an energy-efficient manner.

[0057] Furthermore, according to this embodiment, the non-operation determination time of the heating circulation pumps 51, 52 and the gas heat source units 501, 502 is set according to the outside air temperature, so that the non-operation determination time of the gas heat source units 501, 502 can be set more appropriately according to the heat dissipation condition of the piping.

[0058] As described above, according to this embodiment, hot water can be dispensed from the hot water dispensing terminal 400 at a stable hot water temperature, and a hot water supply system with excellent temperature control performance can be provided, thereby improving user convenience and comfort. [Explanation of symbols]

[0059] 2 water tanks 3 Water supply pipe 35 Pressure Sensor 36 Water volume sensor 37 Water supply pressure pump 6 Hot water tank 40 Heating supply pipe 44 Heat return pipe 51,52 Heating circulation pump 71 Hot water supply pipe 72 Hot water return pipe 501,502 Gas heat source machine C. Hot water control device C1, C2 Heat source machine control device

Claims

1. A heating source; a hot water storage tank for storing hot water heated by a heating heat source; A heating supply pipe connected to the bottom of the hot water storage tank and sending hot water from the hot water storage tank to the heating heat source; A heating return pipe connected to the top of the hot water storage tank and returning hot water from the heating heat source to the hot water storage tank; a heating circulation pump that circulates hot water between the heating heat source and the hot water storage tank; A hot water supply pipe connected to the top of the hot water storage tank and supplying hot water from the hot water storage tank to the hot water outlet terminal; a control device that executes piping heat retention control to keep the heating return pipe warm, The control device is a hot water supply system having a control configuration that, when the heating heat source and heating circulation pump are in an inoperative state for a predetermined inoperative judgment time or longer and the heating circulation pump is activated, operates the heating circulation pump for a predetermined heat retention operation time without activating the heating heat source if the temperature of the hot water in the hot water storage tank is equal to or higher than a predetermined heat retention judgment temperature near a predetermined hot water storage set temperature.

2. In the hot water supply system according to claim 1, The control device is a hot water supply system in which, when the heating heat source and heating circulation pump have been in an inoperative state for longer than the inoperative judgment time and the heating circulation pump is activated, if the temperature of the hot water in the hot water storage tank is below a predetermined heat retention judgment temperature near a predetermined hot water storage set temperature, the control device continues to operate the heating circulation pump and activates the heating heat source.

3. A heating heat source; a hot water storage tank for storing hot water heated by a heating heat source; A heating supply pipe connected to the bottom of the hot water storage tank and sending hot water from the hot water storage tank to the heating heat source; A heating return pipe connected to the top of the hot water storage tank and returning hot water from the heating heat source to the hot water storage tank; a heating circulation pump that circulates hot water between the heating heat source and the hot water storage tank; A hot water supply pipe connected to the top of the hot water storage tank and supplying hot water from the hot water storage tank to the hot water outlet terminal; a control device that executes piping heat retention control to keep the heating return pipe warm, The control device determines whether the temperature of the hot water in the hot water storage tank is close to a predetermined hot water storage setting temperature when the heating heat source and the heating circulation pump are in an inoperative state for more than an inoperative determination time and the heating circulation pump is operated. A hot water supply system that continues to operate the heating circulation pump and activates the heating heat source if the temperature is below a predetermined temperature for heat retention.

4. 4. The hot water supply system according to claim 2 or 3, The control device is a hot water supply system that sets the outlet temperature of the hot water heated by the heating heat source to a predetermined outlet temperature for keeping the water warm, which is higher than the hot water storage set temperature, and operates the heating heat source.

5. The hot water supply system according to claim 4, The control device is a hot water supply system that stops the heating heat source and the heating circulation pump when, when hot water is discharged from the heating heat source at a hot water outlet temperature for keeping the temperature of the hot water, the temperature of the hot water flowing from the heating return pipe into the hot water storage tank reaches or exceeds a predetermined first heat retention stop temperature that is higher than the heat retention judgment temperature, or when the temperature of the hot water in the hot water storage tank reaches or exceeds a predetermined second heat retention stop temperature that is higher than the hot water storage set temperature.

6. In the hot water supply system according to any one of claims 1 to 5, The control device is a hot water supply system that sets the inoperative determination time depending on the outside temperature.

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