JP7762595B2 - Hot water system - Google Patents

Description

The present invention relates to a hot water supply system that is equipped with a hot water storage tank, a heating source, etc. and supplies hot water to hot water outlet terminals such as showers and faucets.

Conventionally, in order to be able to supply a sufficient amount of hot water even when multiple hot water taps (hot water outlet terminals) such as showers and faucets are used simultaneously, a hot water supply system is known that includes a heating heat source, a hot water storage tank that stores hot water heated by the heating heat source, a heating circulation circuit that circulates the hot water between the heating heat source and the hot water storage tank, a hot water supply pipe that supplies hot water from the hot water storage tank to the hot water outlet terminal, a pump that supplies hot water from the hot water storage tank to the heating heat source, and a thermistor that detects the temperature of the hot water from the bottom of the hot water storage tank (Patent Document 1).

Japanese Patent Application Publication No. 9-303808

In the above-mentioned conventional hot water supply system, when performing a boiling operation to heat the hot water in the hot water storage tank using a heating heat source, the hot water temperature at the bottom of the hot water storage tank is detected by a thermistor, and when the hot water temperature at the bottom of the hot water storage tank drops to the starting temperature (45°C in Patent Document 1), the pump is activated to start the boiling operation and heat the hot water in the hot water storage tank, and when the hot water temperature at the bottom of the hot water storage tank rises to the ending temperature (49°C in Patent Document 1), the pump is stopped and the boiling operation is ended.

When hot water is used at a hot water outlet terminal such as a shower, water flows into the hot water storage tank and is supplied to the hot water outlet terminal, which can easily cause the temperature of the hot water in the hot water storage tank to drop. In systems like the conventional hot water supply systems described above, which control the boiling operation based on the hot water temperature at the bottom of the hot water storage tank, the temperature of the hot water in the hot water storage tank changes significantly when the boiling operation is performed while hot water is being dispensed from the hot water outlet terminal. In particular, when the flow rate from the heating source into the hot water storage tank due to the boiling operation is greater than the flow rate used at the hot water outlet terminal, the boiling operation tends to start and stop repeatedly, causing the temperature of the hot water supplied from the hot water storage tank to the hot water outlet terminal to rise and fall repeatedly, resulting in the problem of the hot water temperature from the hot water outlet terminal becoming unstable.

The present invention was made in consideration of the above circumstances, and aims to provide a hot water supply system that suppresses intermittent operation of the heating heat source when boiling operation is performed while hot water is being dispensed from the hot water dispense terminal, thereby making it possible to stabilize the temperature of the hot water dispensed from the hot water dispense terminal.

The hot water supply system according to the present invention comprises:
a heating source that heats hot water and has a variable heating amount;
a hot water storage tank for storing hot water heated by a heating heat source;
a heating circulation circuit that circulates hot water between the heating heat source and the hot water storage tank;
a hot water supply flow path that supplies hot water from the hot water storage tank to the hot water outlet terminal;
a pump provided in the heating circulation circuit for supplying hot water to the heating heat source at a predetermined heat source flow rate;
and a control device that controls a boiling operation in which the pump is operated to heat the hot water in the hot water storage tank with a heating heat source,
When a boiling operation is performed while hot water is being dispensed from the hot water dispensing terminal, the control device is configured to control the termination condition of the boiling operation to be when a certain relationship is satisfied in which the hot water dispensing temperature at the heating heat source can exceed the hot water dispensing set temperature even when the heating heat source is operated with the minimum amount of heat.

With this configuration, when the boiling operation is performed by the heating heat source while hot water is being dispensed from the hot water dispensing terminal, the boiling operation continues unless the temperature of the hot water heated by the heating heat source exceeds the set hot water dispense temperature. In other words, compared to conventional cases where the boiling operation is terminated when the temperature of the hot water in the lower part of the hot water storage tank becomes high, the boiling operation is less likely to terminate even when the temperature of the hot water in the lower part of the hot water storage tank is high. By setting the condition for terminating the boiling operation to when the above-mentioned certain relationship is satisfied, the heating amount of the heating heat source can be minimized, allowing the boiling operation to continue as long as possible. Therefore, while hot water is being dispensed from the hot water dispensing terminal, intermittent operation of the heating heat source, such as repeatedly ending and starting the boiling operation by the heating heat source, can be suppressed, thereby stabilizing the hot water dispensed temperature at the hot water dispensing terminal.

In the hot water supply system,
It is determined based on the minimum heat quantity of the heating heat source, the hot water outlet temperature setting, and the water supply temperature, and the flow rate at which the heating heat source starts heating the hot water is the heat source starting water volume.
The certain relationship may be a relationship in which the heat source flow rate is equal to or less than the heat source initial water flow rate.
Here, the heat source initiation water amount is, for example, the heat source ignition water amount (the minimum amount of water required to ignite the gas burner with the minimum amount of heat) when the heating heat source is a gas heat source machine.

With this configuration, the condition for ending the boiling operation is when the heat source flow rate is equal to or less than the heat source starting water volume. Therefore, even when the heating heat source is operated with the minimum amount of heat, the boiling operation by the heating heat source will continue unless the hot water outlet temperature after heating approaches the set hot water outlet temperature. Therefore, even when the hot water temperature at the bottom of the hot water storage tank is high, the heating heat source can be operated with the minimum amount of heat and the boiling operation will continue. Therefore, while hot water is being dispensed from the hot water dispensing terminal, intermittent operation of the heating heat source can be minimized as much as possible, ensuring a stable hot water temperature at the hot water dispensing terminal.

In the hot water supply system,
It is determined based on the minimum heat quantity of the heating heat source, the hot water outlet temperature setting, and the water supply temperature, and the flow rate at which the heating heat source stops heating the hot water is defined as the heat source stop water volume.
The certain relationship may be a relationship in which the heat source flow rate is equal to or less than the heat source stop water flow rate.
Here, the amount of water to stop the heat source is, for example, the amount of water to extinguish the heat source when the heating heat source is a gas heat source (the minimum amount of water when burner combustion cannot be maintained even with the minimum amount of heat and the fire must be extinguished).

With this configuration, the condition for ending the boiling operation is when the heat source flow rate is equal to or less than the heat source stop water volume. Therefore, even when the heating heat source is operated with the minimum amount of heat, the boiling operation by the heating heat source will continue unless the outlet temperature of the heated hot water exceeds the set hot water outlet temperature or is close to exceeding the set hot water outlet temperature. Therefore, even when the temperature of the hot water at the bottom of the hot water storage tank is high, the heating heat source can be operated with the minimum amount of heat and the boiling operation can continue. Therefore, intermittent operation of the heating heat source can be further suppressed while hot water is being dispensed from the hot water dispense terminal, thereby further ensuring the stability of the hot water dispense temperature at the hot water dispense terminal.

In the hot water supply system,
The condition for ending the boiling operation may further be that the state in which the certain relationship is satisfied continues for a predetermined period of time.

As a result, the boiling operation by the heating heat source continues unless the state satisfying the above-mentioned certain relationship continues for a predetermined time, so the boiling operation can be continued until it can be determined that the hot water outlet temperature from the heating heat source will exceed the set hot water outlet temperature. Therefore, while hot water is being dispensed from the hot water dispensing terminal, intermittent operation of the heating heat source can be further suppressed, further ensuring the stability of the hot water outlet temperature at the hot water dispensing terminal.

1 is a schematic configuration diagram illustrating an example of a hot water supply system according to an embodiment. 10 is a flowchart showing the processing of the boiling operation by the heating heat source while hot water is being dispensed at the hot water dispensing terminal.

Hereinafter, a hot water supply system according to an embodiment of the present invention will be described.
The hot water supply system A of the embodiment shown in FIG. 1 is a hot water supply system that can be used in commercial facilities such as hair salons. It includes a hot water pressurized tank unit 1, a heat source unit 500, and a control device C, and is configured to supply a large amount of cold water or hot water from the hot water pressurized tank unit 1 to multiple hot water outlet terminals 400, such as showers and faucets, which serve as hot water taps. The heat source unit 500 includes a first gas heat source unit 501 and a second gas heat source unit 502, which serve as 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. Note that the hot water supply system A may include one or three or more gas heat source units as heating heat sources, and a heat pump, electric heater, or the like may be used instead of the gas heat source units.

The first and second gas heat source units 501, 502 are gas water heaters and have a heat exchanger 91 and a gas burner 92 inside the housing. 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 hot water heated by the first and second gas heat source units 501, 502 to the hot water storage tank 6.

The first and second gas heat source units 501, 502 are provided with a water volume sensor (water volume detection means) 93 on the water inlet pipe connected between the heating supply pipe 40 (41, 42) and the heat exchanger 91, which detects the inlet volume (heat source flow rate) of hot water entering the heat exchanger 91. The first and second gas heat source units 501, 502 are provided with an outlet hot water temperature sensor (outlet hot water temperature detection means) 94 on the hot water outlet pipe connected between the heating return pipe 44 (45, 46) and the heat exchanger 91, which detects the outlet temperature of the hot water heated by the heat exchanger 91 and discharged. Furthermore, the first and second gas heat source units 501, 502 are configured so that the heating amount (combustion amount) of the gas burner 92 can be changed from minimum to maximum.

One end of the heating supply pipe 40 is connected to the bottom of the hot water storage tank 6, and the other end branches into a first heating supply pipe 41 and a second heating supply pipe 42 so that they are connected to the first gas heat source unit 501 and the 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 connected to the gas heat source units 501 and 502 at one end, and is connected to the top of the hot water storage tank 6 at the other end. A heating supply temperature sensor 50 is installed in the heating supply pipe 40 upstream of the branch point of the first and second heating supply pipes 41 and 42, and downstream of the junction with the water supply pipe 3.

A first heating circulation pump 51 and a second heating circulation pump 52 are installed in the first and second heating supply pipes 41, 42, respectively, and check valves 53, 54 are installed downstream of the first and second heating circulation pumps 51, 52. Therefore, by operating the first and second heating circulation pumps 51, 52 and the first and second gas heat source units 501, 502, hot water heated by the first and second gas heat source units 501, 502 is stored in the hot water storage tank 6. The first and second heating circulation pumps 51, 52 are connected to the hot water supply control device C0 provided in the hot water supply tank unit 1, and their operation, stopping, and rotation speed are controlled by control signals from the hot water supply control device C0.

The first and second gas heat source units 501, 502 are each equipped with a heat source unit control device C1, C2 that controls the operation of the heat source unit, such as combustion control of the gas burner 92. The heat source unit control devices C1, C2 are connected to communicate with the hot water supply control device C0, and the operation and shutdown of the first and second gas heat source units 501, 502 are also controlled by control signals from the hot water supply control device C0. A detection signal for the detected temperature detected by the heating supply temperature sensor 50 is output to the hot water supply control device C0, and detection signals for the detected values detected by various sensors, such as the water volume sensor 93 and the hot water outlet temperature sensor 94, arranged within the gas heat source units 501, 502 are output to the heat source unit control devices C1, C2. The hot water supply control device C0 can recognize the detected values of the various sensors in the first and second gas heat source units 501, 502 via the heat source unit control devices C1, C2. The heat source device control devices C1 and C2 control the heating amount of the gas burner 92 between minimum and maximum heat amounts based on the hot water outlet setting temperature, the water supply temperature, the inflow water volume (heat source flow rate) detected by the water volume sensor 93, and the hot water outlet temperature detected by the hot water outlet temperature sensor 94. The hot water outlet setting temperature is set in the heat source device control devices C1 and C2 by a control signal from the hot water supply control device C0 as the temperature of the hot water supplied to the hot water storage tank 6. The water supply temperature is a recognized water supply temperature value calculated by the heat source device control devices C1 and C2 from the hot water outlet temperature, the water supply volume, and the heating amount of the gas burner 92. However, an inflow water temperature sensor (inflow water temperature detection means) may be provided in the water inflow pipe connected between the heating supply pipe 40 (41, 42) and the heat exchanger 91, and the detected value of this inflow water temperature sensor may be used. Alternatively, the temperature detected by the heating supply temperature sensor 50 may be used as the water supply temperature.

The heating supply pipe 40, connected to the bottom of the hot water storage tank 6, is equipped with an under-tank temperature sensor 55, which detects the temperature of the hot water supplied from the hot water storage tank 6 to the heating supply pipe 40, and a valve 56, located upstream of the junction with the water supply pipe 3. A detection signal for the detected temperature detected by the under-tank temperature sensor 55 is output to the hot water supply control device C0. The valve 56 can be opened and closed manually, but it may also be configured to be opened and closed by a control signal from the hot water supply control device C0.

The hot water storage tank 6 is a tank made of a highly corrosion-resistant metal (e.g., stainless steel), and although not shown, its outer periphery is covered with insulating material. The capacity of the hot water storage tank 6 in this embodiment is, for example, 50 liters. A heating supply pipe 40 and a hot water return pipe 72 that returns hot water from the hot water outlet terminal 400 are connected to the bottom of the hot water storage tank 6, and a heating return pipe 44 and a hot water supply supply pipe 71 that connects to the hot water outlet terminal 400 are connected to the top of the hot water storage tank 6. A first hot water storage temperature sensor 61, a second hot water storage temperature sensor 62, and a third hot water storage temperature sensor 63, each consisting of a thermistor or the like, are attached to the surface of the hot water storage tank 6, in that order from top to bottom, at a predetermined interval to detect the temperature of the hot water inside. The first hot water temperature sensor 61 mainly detects the temperature of the upper layer of hot water in the hot water storage tank 6, the second hot water temperature sensor 62 mainly detects the temperature of the middle layer of hot water in the hot water storage tank 6, and the third hot water temperature sensor 63 mainly detects the temperature of the lower layer of hot water in the hot water storage tank 6. The hot water pressurization tank unit 1 also has, at the bottom of the housing, an outside air temperature sensor 80 that detects the outside air temperature, and a water leakage sensor 81 that detects water leakage within the hot water pressurization tank unit 1. Detection signals such as detected temperatures detected by these sensors 61, 62, 63, 80, and 81 are output to the hot water supply control device C0.

The heating return pipe 44 connected to the top of the hot water storage tank 6 is fitted with an automatic air vent valve 57 for venting air from the hot water storage tank 6, and a heating return temperature sensor 58 for detecting the temperature of the hot water flowing into the hot water storage tank 6. A detection signal of the detected temperature detected by the heating return temperature sensor 58 is output to the hot water supply control device C0.

The water supply tank 2 is disposed above the hot water storage tank 6 and stores water to supply to the gas heat source units 501, 502, the hot water storage tank 6, the hot water outlet terminal 400, etc. In this embodiment, the capacity of the water supply tank 2 is, for example, 70 liters. 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, 12 are respectively provided with, from upstream to downstream, 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, 16 are connected to the hot water supply control device C0 and are controlled to open and close by control signals from the hot water supply control device C0. In this way, by connecting multiple primary water supply pipes 11, 12 to the water supply tank 2, pressure loss is reduced and water can be supplied to the water supply tank 2 in a short period of time. Although not shown, part of the water supply tank 2 is open to the atmosphere.

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 this opening in the side wall. On the other side wall of the water supply tank 2, an overflow float sensor 22, a Hi float sensor 23, a Low float sensor 24, and a low water level float sensor 25, which detect the water level in the water supply tank 2, are arranged in this order from top to bottom at a predetermined interval. A roughly U-shaped trap pipe 201 is provided within the water supply tank 2. One end of the trap pipe 201 is connected to the overflow pipe 200, and the other end is open upward at approximately the same height as the overflow float sensor 22. Therefore, excess water is discharged to the outside through the trap pipe 201 and overflow pipe 200. The trap pipe 201 is sealed to prevent water from collecting and introducing odors, bacteria, etc. from downstream. The water level detection signals detected by each float sensor 22, 23, 24, and 25 are output to the hot water supply control device C0.

The water supply pipe 3, one end of which is connected to the bottom of the water supply tank 2, 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 C0, and its operation, stoppage, and rotation speed are controlled by control signals from the hot water supply control device C0.

The first water supply pipe 31 is provided with, from upstream to downstream, a check valve 33 and a pressure sensor 35 that detects water pressure. The second water supply pipe 32 is provided with, from upstream to downstream, a check valve 34 and a water volume sensor 36 that detects water flow rate. It is possible to install a pressure sensor and a water volume sensor in a single water channel without providing parallel water channels. However, by forming water channels so that water flows in parallel and installing a pressure sensor and a water volume sensor in each channel, pressure loss can be reduced. Although the water flow rate differs in each water channel, 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 signal for the detected pressure detected by the pressure sensor 35 and the detection signal for the detected flow rate detected by the water volume sensor 36 are output to the hot water supply control device C0.

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. Furthermore, downstream of the junction of the first and second water supply pipes 31, 32, the water supply pipe 3 branches into a water supply supply pipe 38 connected to the hot water outlet terminal 400. 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, 502, and the hot water outlet terminal 400, and the water supply pipe 3, including the first and second water supply pipes 31, 32 and the water supply supply pipe 38, constitutes a water supply circuit. The water supply 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 installed in the water supply pipe 3 downstream of the branch point of the water supply pipe 38.

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 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.

To summarize the main operational controls in the hot water supply system A of this embodiment, when the hot water tap of the hot water outlet terminal 400 is opened and the water supply pressure pump 37 starts operating, 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, 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, causing hot water to be dispensed at the hot water outlet terminal 400. Furthermore, the supply of water into the hot water storage tank 6 reduces the temperature of the hot water, and when the temperature of the hot water detected by the third hot water temperature sensor 63 falls below the hot water storage operation start temperature, the first and second heating circulation pumps 51, 52 start operating. By operating the first and second heating circulation pumps 51, 52, hot water is supplied from the bottom of the hot water storage tank 6 to the heating supply pipe 40, and 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, thereby performing the boiling operation by the first and second gas heat source units 501, 502. The hot water heated to a predetermined hot water outlet temperature by the boiling operation by the first and second gas heat source units 501, 502 is returned to the hot water storage tank 6 via the heating return pipe 44, and hot water is also sent from the hot water storage tank 6 to the hot water supply supply pipe 71 and supplied to the hot water outlet terminal 400 via the hot water supply supply pipe 71, thereby dispensing hot water at the hot water outlet terminal 400 (hot water outlet control). In this hot water discharge control, the rotation speeds of the first and second heating circulation pumps 51, 52 are controlled to a constant rotation speed, and a constant flow rate of hot water is supplied from the first and second heating supply pipes 41, 42 to the first and second gas heat source units 501, 502. Note that in the present invention, the rotation speeds of the first and second heating circulation pumps 51, 52 can be controlled to vary the flow rate (heat source flow rate) of hot water supplied from the first and second heating supply pipes 41, 42 to the first and second gas heat source units 501, 502. For example, to reduce the load at pump startup, the heating circulation pumps may be started at a low rotation speed and gradually increased to the rated rotation speed. Alternatively, to mitigate changes in the heat output of the gas burners 92 of the gas heat source units 501, 502, the rotation speeds of the heating circulation pumps 51, 52 may be controlled to vary the heat source flow rate to the gas heat source units 501, 502.
The operation when the boiling operation is performed while hot water is being dispensed from the hot water dispensing terminal 400 will be described in detail later.

Furthermore, when all hot water outlet terminals 400 are closed and the hot water temperature detected by the third hot water storage temperature sensor 63 falls below the hot water storage operation start temperature, the first and second heating circulation pumps 51, 52 begin operation, and the hot water in the hot water storage tank 6 is supplied to the first and second gas heat source units 501, 502 via the heating supply pipe 40.The hot water heated to the specified hot water outlet temperature by the boiling operation of the first and second gas heat source units 501, 502 is returned to the hot water storage tank 6 via the heating return pipe 44, thereby maintaining the temperature of the hot water in the hot water storage tank 6 (hot water storage control).

In addition, when all hot water outlet terminals 400 are closed and the specified instant hot water operation start time has elapsed and the temperature of the hot water remaining in the hot water supply pipe 71 and hot water return pipe 72 has dropped, the instant hot water circulation pump 73 will begin operating, and the hot water in the hot water storage tank 6 will be sent to the hot water supply pipe 71 and hot water return pipe 72 between the hot water storage tank 6 and the hot water outlet terminals 400 (instant hot water control).

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 supply terminal 400, and the first and second gas heat source units 501, 502 are also operated simultaneously or individually accordingly.

The hot water supply system A comprises a hot water supply control device C0 provided in the hot water supply pressurized tank unit 1, heat source unit control devices C1 and C2 provided in the first and second gas heat source units 501 and 502, and a remote control R that allows the user to perform operations related to the operation of the hot water supply system. The hot water supply control device C0 and the heat source unit 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 C0 and the remote control R are connected to each other by wire or wirelessly so that they can communicate with each other.

The remote control R is a terminal device configured to instruct the hot water supply control device C0 on operational information such as turning the power of the hot water supply system A on and off, the set hot water storage temperature in the hot water storage tank 6 (the set hot water outlet temperature of the hot water supplied 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 A. Note that a mobile device such as a smartphone or tablet connected to the hot water supply control device C0 so as to be able to communicate with it can be used instead of, or in addition to, the remote control R.

The hot water supply control device C0 and the heat source device 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 operating programs and various data such as setting values for executing the operating programs.

The hot water supply control device C0 receives detection signals from the various sensors previously described (temperature sensors 50, 55, 58, 61, 62, 63, 74, 80, 81, pressure sensor 35, water volume sensor 36, float sensors 22-25, etc.), and also receives operational information from the remote control R. The heat source unit control devices C1 and C2 also receive detection signals from various sensors (water volume sensor 93, hot water outlet temperature sensor 94, etc.) installed in the first and second gas heat source units 501 and 502, and output control signals to the hot water supply control device C0. The hot water supply control device C0 then controls the operation of the entire hot water supply system by controlling the operation of the gas heat source units 501 and 502, the various pumps 37, 51, 52, 73, the water supply solenoid valves 15 and 16, etc. Therefore, in this embodiment, the hot water supply control device C0 and the heat source unit control devices C1 and C2 constitute the control device C of the hot water supply system A. Note that the operation of the entire hot water supply system may be controlled by a single control device without providing heat source machine control devices C1 and C2, or the hot water supply control device C0 may constitute the control device C of the hot water supply system A.

Next, the characteristic features of the present invention will be described.
In a conventional hot water supply system (Patent Document 1), in which the start and end of the boiling operation by the heating heat source is controlled based on the temperature of the hot water at the bottom of the hot water storage tank, if the boiling operation is performed while the hot water is being dispensed from the hot water dispense terminal, the temperature of the hot water in the hot water storage tank changes significantly. In particular, if the flow rate from the heating heat source to the hot water storage tank due to the boiling operation is greater than the flow rate used at the hot water dispense terminal, the boiling operation tends to start and end repeatedly, causing the hot water supplied from the hot water storage tank to the hot water dispense terminal to repeatedly rise and fall in temperature, resulting in an unstable hot water temperature. Furthermore, immediately after the start of operation of the heating heat source, the temperature of the hot water dispensed from the heating heat source is relatively unstable, making it difficult for the temperature of the hot water supplied to the hot water storage tank to stabilize. Therefore, if the boiling operation is performed intermittently, the hot water temperature dispensed from the hot water dispense terminal becomes unstable. Therefore, when the boiling operation is performed by the heating heat source while hot water is being dispensed from the hot water dispensing terminal, if the heating heat source operates intermittently frequently and the boiling operation is performed intermittently, the temperature of the hot water dispensed from the hot water dispensing terminal will no longer be stable.
In the hot water supply system A of this embodiment, when a boiling operation is performed while hot water is being dispensed from the hot water dispensing terminal 400, the intermittent operation of the heating heat sources (501, 502) is suppressed as much as possible.
In other words, in the hot water supply system A of this embodiment, when the boiling operation is performed by the first and second gas heat source units 501, 502 while hot water is being dispensed at the hot water dispensing terminal 400, the control device C is characterized by controlling the termination condition of the boiling operation to be when a certain relationship is satisfied in which the hot water dispensing temperature at the first and second gas heat source units 500, 501 exceeds the hot water dispensing set temperature even when the first and second gas heat source units 500, 501 are operated with the minimum amount of heat.

The certain relationship is determined based on the minimum heat quantity, hot water outlet setting temperature, water supply temperature, and heat source flow rate q of the first and second gas heat source units 500, 501, and is a relationship such that the heat source flow rate q is equal to or less than the heat source ignition water quantity Qs (heat source initiation water quantity). Here, the heat source flow rate q is the inlet water quantity of hot water flowing into the gas heat source units (501, 502) operating when the end of the boiling operation is determined, and is the detected flow rate detected by the water quantity sensor 93 mounted on the gas heat source units (501, 502). The heat source ignition water quantity Qs is the minimum water quantity required to ignite the gas burner 92 with the minimum heat quantity of the gas heat source units (501, 502) (i.e., the water quantity at which the gas heat source units (501, 502) start heating the hot water), and is determined by the following formula:
Heat source ignition water volume = minimum heat amount x n ÷ (outlet water setting temperature - supply water temperature) ... (formula)
In the above formula, n is an arbitrary value greater than 1.0 and equal to or less than 1.5, and in this embodiment, it is set to 1.1.
Here, the minimum heat quantity is the minimum heat quantity (preferably a heat quantity including thermal efficiency) in the heating capacity of the gas heat source unit (501, 502). The hot water outlet setting temperature is a setting temperature set in the gas heat source unit (501, 502) so that the hot water outlet temperature flowing out from the gas heat source unit (501, 502) becomes the hot water storage setting temperature of the hot water supplied to the hot water storage tank 6. The supply water temperature is the temperature of the hot water flowing into the gas heat source unit (501, 502). This water supply temperature is a recognized value calculated from the formula: "outlet water temperature - (heating amount ÷ heat source flow rate)" based on the heat source flow rate, heating amount (preferably heating amount including thermal efficiency), and outlet water temperature (which may also be the outlet water set temperature) in the gas heat source unit (501, 502).However, a water supply temperature detection means may be provided in the water inlet pipe of the gas heat source unit (501, 502) and the detected temperature may be detected by this water supply temperature detection means, or the detected temperature may be detected by the heating supply temperature sensor 50.

The operation of boiling water in the hot water storage tank 6 while hot water is being dispensed from the hot water dispensing terminal 400 will be described below.
2, when the power of the remote controller R is ON (step S0), the control device C determines whether the amount of water used at the hot water dispensing terminal 400 exceeds a predetermined amount AQ (e.g., 0.1 L/min) to confirm whether hot water is being dispensed at the hot water dispensing terminal 400 (step S1). The amount of water used at the hot water dispensing terminal 400 is the detected flow rate detected by the water volume sensor 36 provided in the second water supply pipe 32. If the amount of water used at the hot water dispensing terminal 400 does not exceed the predetermined amount AQ ("NO" in step S1), it can be confirmed that hot water is not being dispensed at the hot water dispensing terminal 400, and the control device C shifts the process to hot water storage control operation (step S10). In the hot water storage control operation, for example, if the detected temperature T3 of the third hot water storage temperature sensor 63 and the detected temperature of the under-tank temperature sensor 55 remain below the predetermined hot water storage operation start temperature for a predetermined time, one or two heating circulation pumps (51, 52) are operated to heat the hot water in the hot water storage tank 6 using the gas heat source unit (501, 502) and return it to the top of the hot water storage tank 6, and then, when the detected temperature of the under-tank temperature sensor 55 remains above the predetermined hot water storage operation end temperature for a predetermined time, the heating circulation pumps (51, 52) are stopped and the hot water storage control operation is terminated.

On the other hand, if the amount of water used at the hot water supply terminal 400 exceeds the predetermined amount AQ ("YES" in step S1), it is confirmed that hot water is being dispensed from the hot water supply terminal 400, and the control device C recognizes that both the first and second heating circulation pumps 51, 52 are stopped ("YES" in step S1-1), it determines whether the temperature T3 detected by the third hot water temperature sensor 63, which indicates the temperature of the hot water in the lower layer of the hot water storage tank 6, has remained below a predetermined temperature A (e.g., 55°C) for a predetermined time t1 (e.g., 1 second) (step S2). If the temperature T3 detected by the third hot water temperature sensor 63 has remained below the predetermined temperature A for a predetermined time t1 ("YES" in step S2), it is confirmed that the temperature of the hot water in the lower layer of the hot water storage tank 6 has dropped, and the control device C activates one heating circulation pump (first heating circulation pump 51) (step S3). This causes one gas heat source unit (first gas heat source unit 501) to perform a boiling operation. In this case, the hot water in the hot water storage tank 6 is heated by the first gas heat source unit 501 via the first heating supply pipe 41 and the first heating return pipe 45 and supplied to the upper part of the hot water storage tank 6.

In step S2, if the detected temperature T3 of the third hot water temperature sensor 63 is equal to or higher than the predetermined temperature A or has not remained below the predetermined temperature A for the predetermined time t1 ("NO" in step S2), it can be confirmed that the temperature of the hot water in the lower layer of the hot water tank 6 has not dropped, and the control device C returns the process to step S1 and monitors whether hot water is being dispensed at the hot water dispensing terminal 400. Note that in step S1-1, if the control device C recognizes that neither the first nor second heating circulation pumps 51, 52 is stopped ("NO" in step S1-1), the process proceeds to step S3-1.

When a boiling operation is performed by one first gas heat source unit 501 in step S3, if there is an inactive heating circulation pump (50, 51) ("YES" in step S3-1), the next step S4 determines whether to perform boiling operation on two more gas heat source units 501, 502. That is, the control device C determines whether the detected temperature T2 of the second hot water temperature sensor 62, which indicates the temperature of the hot water in the middle layer of the hot water storage tank 6, has remained below a predetermined temperature B (e.g., 53°C) for a predetermined time t2 (e.g., 5 seconds) (step S4). If the detected temperature T2 of the second hot water temperature sensor 62 has remained below the predetermined temperature B for the predetermined time t2 ("YES" in step S4), it is confirmed that the hot water temperature has dropped to below the middle layer of the hot water storage tank 6, and the control device C activates the stopped heating circulation pump (second heating circulation pump 52). This activates the second gas heat source unit 502, and the two gas heat source units 501, 502 perform boiling operations. In this case, the hot water in the hot water storage tank 6 is heated by the first and second gas heat source units 501, 502 via the first and second heating supply pipes 41, 42 and the first and second heating return pipes 45, 46, and supplied to the upper part of the hot water storage tank 6.

In step S4, if the detected temperature T2 of the second hot water temperature sensor 62 is equal to or higher than the predetermined temperature B or has not remained below the predetermined temperature B for the predetermined time t2 ("NO" in step S4), it can be confirmed that the drop in the hot water temperature in the hot water tank 6 is limited to the lower layer and has not reached the middle layer, and the control device C proceeds to step S8 and continues the boiling operation of one gas heat source unit (501). Note that in step S3-1, if the control device C recognizes that there are no heating circulation pumps that are not in operation ("NO" in step S3-1), it proceeds to step S6.

After the two gas heat source units 501, 502 perform the boiling operation in step S5, the next step S6 determines whether to switch to boiling operation using one gas heat source unit as the hot water temperature in the hot water storage tank 6 rises. That is, the control device C determines whether the detected temperature T3 of the third hot water storage temperature sensor 63, which indicates the temperature of the hot water in the lower layer of the hot water storage tank 6, remains above a predetermined temperature C (e.g., 55°C) for a predetermined time t3 (e.g., 5 seconds) (step S6). If the detected temperature T3 of the third hot water storage temperature sensor 63 remains above the predetermined temperature C for the predetermined time t3 ("YES" in step S6), it can be confirmed that the temperature of the hot water in the lower layer of the hot water storage tank 6 has risen, and the control device C stops the first heating circulation pump 51, which was activated initially, and operates only the second heating circulation pump 52 (step S7). As a result, heating by the first gas heat source unit 501 stops, and boiling operation is performed by only the second gas heat source unit 502. In this case, hot water in the hot water storage tank 6 is heated by the second gas heat source unit 502 via the second heating supply pipe 42 and second heating return pipe 46 and supplied to the upper part of the hot water storage tank 6.

In step S6, if the detected temperature T3 of the third hot water storage temperature sensor 63 is below the predetermined temperature C or has not remained at or above the predetermined temperature C for the predetermined time t3 ("NO" in step S6), it can be determined that the temperature has not yet risen to the lower layers of hot water in the hot water storage tank 6, and the control device C returns the process to step S1 and monitors whether hot water is being dispensed at the hot water dispensing terminal 400. In addition, in the first and second gas heat source units 501, 502, the heat source unit control devices C1, C2 control the heating amount of the gas burner 92 to change so that the hot water temperature detected by the hot water outlet temperature sensor 94 matches the hot water outlet set temperature, and at the end of the boiling operation, the heating amount of the gas burner 92 is set to the minimum amount of heat to heat the hot water.

After the boiling operation is performed in one gas heat source unit through the above processing operations, the completion of the boiling operation is determined.
The end of the boiling operation is determined by whether a predetermined end condition is satisfied. That is, the control device C determines whether the heat source flow rate q has remained equal to or less than the heat source ignition water amount Qs for a predetermined time t4 (e.g., 3 seconds) as the end condition (step S8). If the heat source flow rate q has not remained equal to or less than the heat source ignition water amount Qs for the predetermined time t4 ("NO" in step S8), the process returns to step S1. On the other hand, if the heat source flow rate q has remained equal to or less than the heat source ignition water amount Qs for the predetermined time t4 ("YES" in step S8), the heating circulation pump 52 is stopped (step S9). Step S9 stops heating of the second gas heat source unit 502, which stops heating of all gas heat source units 501 and 502, and the boiling operation during hot water dispensing at the hot water dispensing terminal 400 is terminated.

(Effects of the embodiment)
As described above, in this embodiment, when the boiling operation is performed while the hot water dispenser 400 is dispensing hot water, the control device C controls the termination condition of the boiling operation so that a certain relationship is satisfied in which the outlet hot water temperature of the gas heat source unit (501, 502) may exceed the hot water dispense setting temperature even when the gas heat source unit (501, 502) is operated at minimum heat output. That is, the termination condition of the boiling operation is the certain relationship in which the heat source flow rate q is equal to or less than the heat source ignition water amount Qs for a predetermined time t4 (step S8). As a result, when the boiling operation is performed by the gas heat source unit (501, 502) while the hot water dispenser 400 is dispensing hot water, the boiling operation continues unless the outlet hot water temperature heated by the gas heat source unit (501, 502) approaches or exceeds the hot water dispense setting temperature. Therefore, compared to conventional systems that terminate the boiling operation when the hot water temperature at the bottom of the hot water storage tank 6 becomes high, the boiling operation is less likely to terminate even when the hot water temperature at the bottom of the hot water storage tank 6 is high.

The heat source ignition water amount Qs in the above-mentioned certain relationship is the minimum amount of water required to ignite the gas burner 92 of the gas heat source device (501, 502) with the minimum amount of heat, and is determined by the following formula.
Heat source ignition water quantity Qs = minimum heat quantity × 1.1 ÷ (outlet hot water setting temperature - supply water temperature) ... (formula)
In this way, the constant relationship is determined based on the minimum heat amount, hot water outlet temperature setting, water supply temperature, and heat source flow rate q of the gas heat source unit (501, 502), so the heating amount of the gas heat source unit (501, 502) can be minimized to continue the boiling operation as much as possible. As a result, even when the gas heat source unit (501, 502) is operated with the heating amount set to the minimum heat amount, the boiling operation by the gas heat source unit (501, 502) continues unless the hot water outlet temperature after heating is close to exceeding the hot water outlet temperature setting (more specifically, below the hot water outlet temperature and close to the hot water outlet temperature setting). Therefore, even when the hot water temperature in the lower part of the hot water storage tank 6 is high, the heating amount of the gas heat source unit (501, 502) can be set to the minimum heat amount to continue the boiling operation.

The condition for terminating the boiling operation is when the state satisfying the certain relationship continues for a predetermined time t4. As a result, the boiling operation by the gas heat source unit (501, 502) continues unless the state satisfying the certain relationship continues for the predetermined time t4. Therefore, the boiling operation can be continued until it can be determined that the hot water outlet temperature of the gas heat source unit (501, 502) is close to exceeding the hot water outlet set temperature.

As described above, according to the hot water supply system A of this embodiment, while hot water is being dispensed at the hot water dispensing terminal 400, intermittent operation of the gas heat source units (501, 502) can be suppressed, thereby stabilizing the hot water temperature at the hot water dispensing terminal 400. Note that in this embodiment, during the boiling operation, the number of gas heat source units (501, 502) operating varies intermittently, from one to two (step S5 in Figure 2) or from two to one (step S7 in Figure 2), with the two gas heat source units (501, 502) operating intermittently. However, because one gas heat source unit (501 or 502) is always operating, there is little change in the hot water temperature at the hot water dispensing terminal 400, and this does not affect the hot water temperature at the hot water dispensing terminal 400.

(Other embodiments)
In another embodiment, in the process of step S8, the heat source ignition water amount Qs is replaced with a heat source extinguishing water amount Qe (heat source shutdown water amount). Here, the heat source extinguishing water amount Qe refers to the minimum amount of water when the gas heat source unit (501, 502) reduces the combustion of the gas burner 92 to the minimum heat amount but is unable to maintain heating by the burner combustion and has to extinguish the fire (i.e., the amount of water at which the gas heat source unit (501, 502) stops heating hot and cold water). The heat source extinguishing water amount Qe is determined by the following formula:
Heat source fire extinguishing water quantity Qe = minimum heat quantity ÷ (outlet hot water setting temperature - supply water temperature) ... (formula)
Even in this case, the above-mentioned fixed relationship is determined based on the minimum heat quantity, hot water outlet setting temperature, water supply temperature, and heat source flow rate q in the gas heat source unit (501, 502), so that the heating quantity of the gas heat source unit (501, 502) can be minimized to continue boiling operation as much as possible.

In this other embodiment, even when the gas heat source units (501, 502) are operated with the minimum heating amount, the boiling operation by the gas heat source units (501, 502) continues unless the outlet temperature of the heated hot water exceeds the set hot water outlet temperature or is close to exceeding the set hot water outlet temperature (more specifically, is below the set hot water outlet temperature but close to the set hot water outlet temperature). That is, the gas heat source units (501, 502) are operated until the minimum heating amount is reached, and the boiling operation continues. Therefore, even when the temperature of the hot water in the lower part of the hot water storage tank 6 is high, the heating amount of the gas heat source units (501, 502) can be set to the minimum heating amount and the boiling operation can continue. Therefore, intermittent operation of the gas heat source units (501, 502) can be further suppressed while hot water is being dispensed from the hot water dispensing terminal 400, thereby further ensuring the stability of the hot water outlet temperature at the hot water dispensing terminal 400. In another embodiment, the termination condition for the boiling operation is to operate the gas heat source unit (501, 502) using the heat source fire extinguishing water volume Qe until the minimum heat quantity is reached, so the continuation of the specified time t4 may be removed from the termination condition, and the termination condition for the boiling operation may be when the heat source flow rate q is equal to or less than the heat source fire extinguishing water volume Qe.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

1 Hot water supply pressurized tank unit 2 Water supply tank 3 Water supply forward pipe 6 Hot water storage tank 40 Heating forward pipe 41 First heating forward pipe 42 Second heating forward pipe 44 Heating return pipe 45 First heating return pipe 46 Second heating return pipe 51 First heating circulation pump 52 Second heating circulation pump 55 Tank under temperature sensor 61 First hot water storage temperature sensor 62 Second hot water storage temperature sensor 63 Third hot water storage temperature sensor 71 Hot water supply forward pipe 72 Hot water supply return pipe 91 Heat exchanger 92 Gas burner 93 Water volume sensor (water volume detection means)
94 Outlet hot water temperature sensor (outlet hot water temperature detection means)
400 hot water outlet terminal 500 heat source unit 501 first gas heat source (heating heat source)
502 Second gas heat source (heating heat source)
A Hot water supply system C Control device C0 Hot water supply control device C1 Heat source machine control device C2 Heat source machine control device R Remote control

Claims (3)

a heating source that heats hot water and has a variable heating amount;
a hot water storage tank for storing hot water heated by a heating heat source;
a heating circulation circuit that circulates hot water between the heating heat source and the hot water storage tank;
a hot water supply flow path that supplies hot water from the hot water storage tank to the hot water outlet terminal;
a pump provided in the heating circulation circuit for supplying hot water to the heating heat source at a predetermined heat source flow rate;
and a control device that controls a boiling operation in which the pump is operated to heat the hot water in the hot water storage tank with a heating heat source,
The control device is configured to control the termination condition of the boiling operation when the boiling operation is performed while the hot water is being dispensed from the hot water dispensing terminal so that the condition is a case where a certain relationship is satisfied in which the hot water dispensing temperature at the heating heat source exceeds the hot water dispensing set temperature even when the heating heat source is operated with a minimum heat amount ,
It is determined based on the minimum heat quantity of the heating heat source, the hot water outlet temperature setting, and the water supply temperature, and the flow rate at which the heating heat source starts heating the hot water is the heat source starting water volume.
A hot water supply system, wherein the certain relationship is a relationship in which the heat source flow rate is equal to or less than the heat source starting water flow rate . a heating source that heats hot water and has a variable heating amount;
a hot water storage tank for storing hot water heated by a heating heat source;
a heating circulation circuit that circulates hot water between the heating heat source and the hot water storage tank;
a hot water supply flow path that supplies hot water from the hot water storage tank to the hot water outlet terminal;
a pump provided in the heating circulation circuit for supplying hot water to the heating heat source at a predetermined heat source flow rate;
and a control device that controls a boiling operation in which the pump is operated to heat the hot water in the hot water storage tank with a heating heat source,
The control device is configured to control the termination condition of the boiling operation when the boiling operation is performed while the hot water is being dispensed from the hot water dispensing terminal so that the condition is a case where a certain relationship is satisfied in which the hot water dispensing temperature at the heating heat source exceeds the hot water dispensing set temperature even when the heating heat source is operated with a minimum heat amount ,
It is determined based on the minimum heat quantity of the heating heat source, the hot water outlet temperature setting, and the water supply temperature, and the flow rate at which the heating heat source stops heating the hot water is defined as the heat source stop water volume.
A hot water supply system, wherein the certain relationship is a relationship in which the heat source flow rate is equal to or less than the heat source stop water flow rate . 3. The hot water supply system according to claim 1 ,
The hot water supply system further comprises a condition for terminating the boiling operation when the state satisfying the certain relationship continues for a predetermined period of time.