JP2024078738A - Hot water storage system - Google Patents

Abstract

To provide a hot water storage and supply system which can use hot water in a hot water storage tank from a hot water tap at water cutoff.SOLUTION: A hot water storage and supply system (1) having a heat source machine (4), a hot water storage tank (2) for storing hot water which is heated by a hot water storage operation of the heat source machine (4), a hot water discharge passage (12) for discharging the hot water of an upper part of the hot water storage tank (2), and control means (18) for controlling the hot water storage operation, comprises: a mixing valve (14) arranged at the hot water discharge passage (12) for mixing the hot water from the hot water storage tank (2) and service water; a hot water storage passage (8) equipped with a hot water storage pump (7) for sending the hot water at a lower part of the hot water storage tank (2) to the heat source machine (4) at the hot water storage operation; a flow passage selector valve (8a) arranged between the hot water storage pump (7) of the hot water storage passage (8) and the heat source machine (4); and an auxiliary hot water discharge passage (10) branched from the hot water storage passage (8) by the flow passage selector valve (8a), and connected to a part of the hot water discharge passage (12) downstream of the mixing valve (14).SELECTED DRAWING: Figure 1

Description

The present invention relates to a hot water storage and hot water supply system that uses hot water heated by a heat source unit and stored to supply hot water.

Conventionally, hot water storage and hot water supply systems have been widely used as heat source machines with high heating operation efficiency, in which hot water heated by a heat pump unit is stored in a hot water storage tank and the hot water from the hot water storage tank is used to supply hot water. For example, the hot water storage and hot water supply system of Patent Document 1 performs a hot water storage operation in which hot water is introduced from the bottom of the hot water storage tank to a heat pump unit and the hot water heated by the heat pump unit is returned to the top of the hot water storage tank to store high-temperature hot water. When supplying hot water, the hot water discharged from the top of the hot water storage tank is mixed with clean water by a mixing valve to supply hot water with a temperature adjusted.

However, when the water supply is cut off due to a disaster or accident, for example, it may not be restored in a short period of time. In such cases, hot water is stored in the hot water storage tank of the hot water storage and supply system, so the hot water can be taken out and used. A drain plug is provided on the bottom of the hot water storage tank, and the hot water that flows down is taken out using gravity.

Patent No. 5654841

Since hot water storage and hot water supply systems are usually installed outdoors, in order to use the hot water in the hot water storage tank during a water outage, it is necessary to go to the outdoor hot water storage tank to retrieve the hot water. In addition, a container is required to receive the retrieved hot water, and the hot water in this container must be transported to the place where it will be used. As a result, using the hot water in the hot water storage tank during a water outage is time-consuming and inconvenient, there has been a demand for technology that allows hot water to be used in places where hot water is normally used, even during a water outage.

Therefore, the present invention aims to provide a hot water storage and hot water supply system that allows hot water in a hot water storage tank to be used from the hot water tap during a water outage.

The hot water storage and hot water supply system of the invention of claim 1 has a heat source machine, a hot water storage tank for storing hot water heated by the hot water storage operation of the heat source machine, a hot water outlet passage for discharging the hot water from the upper part of the hot water storage tank, and a control means for controlling the hot water storage operation, and is characterized by having a mixing valve provided in the hot water outlet passage for mixing the hot water from the hot water storage tank with tap water, a hot water storage passage equipped with a hot water storage pump for sending the hot water from the lower part of the hot water storage tank to the heat source machine during the hot water storage operation, a flow path switching valve provided in the hot water storage passage between the hot water storage pump and the heat source machine, and an auxiliary hot water outlet passage branched off from the hot water storage passage by the flow path switching valve and connected to a portion of the hot water outlet passage downstream of the mixing valve.

According to the above configuration, the auxiliary hot water outlet passage, which is branched off from the hot water storage passage by the flow path switching valve between the hot water storage pump and the heat source unit, is connected to the part of the hot water outlet passage downstream of the mixing valve. Therefore, hot water can be supplied from the bottom of the hot water storage tank to the hot water outlet passage via the auxiliary hot water outlet passage, so that hot water stored in the hot water storage tank can be conveniently supplied to the hot water tap in the event of a water outage.

The hot water storage and hot water supply system of the invention of claim 2 is characterized in that, in the invention of claim 1, the control means is configured to switch the flow path switching valve to the auxiliary hot water outlet passage side and drive the hot water storage pump, thereby supplying hot water from the hot water storage tank to the hot water outlet passage.
According to the above configuration, the control means switches the flow path switching valve to the auxiliary hot water outlet passage and drives the hot water storage pump, so that hot water in the hot water storage tank can be used through the auxiliary hot water outlet passage. Therefore, when the water supply is cut off, the hot water stored in the hot water storage tank can be supplied to the hot water tap. Even if the water supply is not cut off, when hot water storage operation and hot water supply are not being performed, the hot water in the hot water storage tank can be circulated to prevent the passages of the hot water storage and hot water supply system from freezing.

The hot water storage and hot water supply system of the invention of claim 3 is characterized in that, in the invention of claim 2, it has a flow detection means in a downstream portion of the hot water outlet passage relative to the connection with the auxiliary hot water outlet passage, and the control means stops the hot water storage pump when the detected flow rate of the flow detection means falls below a predetermined reference flow rate while the hot water storage pump is operating.
According to the above configuration, when hot water is being discharged from the hot water storage tank via the auxiliary hot water outlet passage, the hot water storage pump is stopped if the flow rate of hot water discharged from the hot water outlet passage falls below a reference flow rate. Therefore, hot water stored in the hot water storage tank is supplied to the hot water tap during a water outage, and the hot water storage pump can be stopped when the hot water storage tank becomes empty or when the user closes the hot water tap 6. This makes it possible to prevent wear and breakdown of the hot water storage pump and water leakage due to an increase in pressure in the passage to the hot water tap.

The hot water storage and water supply system of the invention of claim 4 is characterized in that, in the invention of claim 1, it has a hot water temperature detection means in a portion of the hot water outlet passage downstream of the connection of the auxiliary hot water outlet passage, and when the hot water temperature detection means detects a temperature higher than a predetermined reference temperature when hot water is discharged from the top of the hot water storage tank, it switches the flow path switching valve to the auxiliary hot water outlet passage side and drives the hot water storage pump.
According to the above configuration, when the mixing valve mixes clean water with hot water from the hot water storage tank for normal hot water supply without using the auxiliary hot water outlet passage, if the temperature of the hot water discharged from the hot water outlet passage is equal to or higher than the reference temperature, the flow path switching valve is switched to the auxiliary hot water outlet passage side to drive the hot water storage pump. Therefore, by mixing low-temperature hot water from the bottom of the hot water storage tank through the auxiliary hot water outlet passage, it is possible to prevent high-temperature hot water above the reference temperature from being discharged due to, for example, a malfunction of the mixing valve, thereby improving safety.

The hot water storage and hot water supply system of the present invention allows hot water in the hot water storage tank to be used from the hot water tap during a water outage, and can also provide other functions during normal times.

1 is an explanatory diagram of a hot water storage and supply system according to an embodiment of the present invention. FIG. 11 is an explanatory diagram for explaining a case in which hot water in a hot water storage tank is used from a hot water tap during a water outage. FIG. 11 is an explanatory diagram for circulating hot water in a hot water storage tank. FIG. 11 is an explanatory diagram for preventing high-temperature hot water from being discharged during normal hot water supply when there is no water outage.

The following describes the form for implementing the present invention based on examples.

First, the configuration of a hot water storage and supply system 1 of the present invention will be described with reference to FIG.
The hot water storage and hot water supply system 1 has a hot water storage unit 3 equipped with a hot water storage tank 2, and a heat source unit 4, such as a heat pump unit, and an auxiliary heat source unit 5, such as a combustion type. This hot water storage and hot water supply system 1 performs a hot water storage operation in which hot water heated to a target hot water storage temperature by the heat source unit 4 is stored in the hot water storage tank 2. The target hot water storage temperature is set, for example, based on a hot water supply setting temperature and a prediction of hot water usage. The auxiliary heat source unit 5 supplies the hot water discharged from the hot water storage unit 3 to a hot water tap 6 with or without heating depending on the temperature.

Next, the hot water storage unit 3 will be described.
A heat source unit supply passage 8 (hot water storage passage) equipped with a hot water storage pump 7 for sending hot water from the hot water storage tank 2 to the heat source unit 4 during hot water storage operation is connected to the bottom of the hot water storage tank 2. A first switching valve 8a (flow path switching valve) for switching the flow path of the hot water is disposed between the hot water storage pump 7 and the heat source unit 4 in the heat source unit supply passage 8, and an auxiliary hot water outlet passage 10 is branched off from the heat source unit supply passage 8 at this first switching valve 8a. Normally, the first switching valve 8a is in a state in which the heat source unit supply passage 8 communicates from the hot water storage tank 2 to the heat source unit 4.

A heat source unit return passage 9 is connected to the top of the hot water storage tank 2 for returning the hot water heated by the heat source unit 4 to the hot water storage tank 2. A second switching valve 9a is provided midway along this heat source unit return passage 9 to switch the flow path of the hot water, and a return branch passage 9b branched off from the heat source unit return passage 9 at this second switching valve 9a is connected to the upstream portion of the hot water storage pump 7 of the heat source unit forward passage 8.

A return temperature sensor 9c that detects the temperature of the hot water heated by the heat source unit 4 is disposed upstream of the second switching valve 9a in the heat source unit return passage 9. For example, since the hot water cannot be heated sufficiently immediately after the heat source unit 4 is started up by starting the hot water storage operation, the second switching valve 9a can be switched from the hot water storage tank 2 side to the return branch passage 9b side, and the hot water can be circulated without being returned to the hot water storage tank 2 until it can be heated sufficiently.

A water supply passage 11 is connected to the bottom of the hot water storage tank 2, supplying clean water indicated by the arrow CW. A hot water outlet passage 12 is connected to the top of the hot water storage tank 2, for discharging hot water from the hot water storage unit 3 to the top of the hot water storage tank 2. A mixing valve 14 is provided in the middle of the hot water outlet passage 12, and a water supply branch passage 11a branched from the middle of the water supply passage 11 is connected to the mixing valve 14. The hot water from the hot water storage tank 2 and the clean water from the water supply branch passage 11a are mixed by the mixing valve 14 and discharged from the hot water storage unit 3. The auxiliary hot water outlet passage 10 branched from the heat source unit forward passage 8 by the first switching valve 8a is connected to the downstream part of the hot water outlet passage 12 from the mixing valve 14. The mixing valve 14 may have a closing function for closing the hot water side and the clean water side, for example.

The hot water storage tank 2 has multiple hot water temperature sensors 2a-2d arranged at a predetermined interval in the vertical direction, which can detect the temperature of the hot water stored in the hot water storage tank 2 and the amount of hot water stored at that temperature. In order to prevent the temperature of the stored hot water from dropping, a heat insulating material (not shown) is arranged to cover the hot water temperature sensors 2a-2d and the hot water storage tank 2.

A supply water temperature sensor 11b is provided in the supply water passage 11 to detect the temperature of the tap water (supply water temperature). A hot water outlet passage 12 is provided with an outlet water flow rate sensor 12a (flow rate detection means) to detect the outlet water flow rate of the hot water from the hot water storage unit 3, a hot water storage tank outlet water temperature sensor 12b to detect the temperature of the hot water from the hot water storage tank 2, and an outlet water temperature sensor 12c (hot water temperature detection means) to detect the outlet water temperature from the hot water storage unit 3.

Below the hot water storage tank 2, a drain passage 11c and an overflow passage 11d branch off from the water supply passage 11. A drain plug 11e is provided in the drain passage 11c. The overflow passage 11d is provided with a relief valve 11f that drains hot water to reduce pressure when the pressure in the hot water storage tank 2 rises above a predetermined value due to thermal expansion caused by hot water storage operation, for example. The relief valve 11f functions as a negative pressure valve that introduces air, and when, for example, the supply of clean water is stopped and the drain plug 11e is opened to drain water from the drain passage 11c, air is introduced to prevent deformation of the hot water storage tank 2.

The hot water outlet passage 12 of the hot water storage unit 3 and the water supply port 5a of the auxiliary heat source unit 5 are connected by a connecting passage 15. The hot water supply port 5b of the auxiliary heat source unit 5 is connected to a hot water supply passage 16 connected to the hot water tap 6. The hot water discharged from the hot water storage unit 3 is supplied to the hot water tap 6 via the auxiliary heat source unit 5.

In hot water storage and hot water supply system 1, during hot water storage operation, the heat source unit 4 and hot water storage pump 7 are driven to circulate hot water between hot water storage tank 2 and heat source unit 4, hot water introduced into heat source unit 4 from the bottom of hot water storage tank 2 is heated, and the hot water is returned to the top of hot water storage tank 2 for storage. As a result, temperature stratification is formed in hot water storage tank 2, consisting of hot water at the target hot water storage temperature in the upper layer and hot water before heating in the lower layer.

The hot water storage unit 3 has a hot water storage unit control unit 18 (control means) that controls the hot water storage operation and controls the temperature adjustment of the hot water discharged from the hot water storage unit 3 during hot water supply. An operation terminal 19 is connected to this hot water storage unit control unit 18, which allows the user to set, for example, the hot water supply setting temperature. This operation terminal 19 is also connected to the auxiliary heat source unit 5, and the hot water storage unit control unit 18 and the auxiliary heat source unit 5 are connected so as to be able to communicate with each other.

Next, a case where hot water stored in the hot water storage tank 2 is supplied to the hot water tap 6 when the water supply is interrupted will be described with reference to Fig. 2. The flow of hot water is indicated by arrows in the passage.
During a water outage, clean water is not supplied from the water supply passage 11, so no hot water comes out even if the hot water tap 6 is opened. Therefore, with the hot water tap 6 open, the hot water storage unit control unit 18 switches the first changeover valve 8a to the auxiliary hot water outlet passage 10 side, closes the mixing valve 14, and drives the hot water storage pump 7, thereby sending hot water from the bottom of the hot water storage tank 2 through the heat source machine supply passage 8 and the auxiliary hot water outlet passage 10 to the hot water outlet passage 12.

At this time, the hot water storage unit control unit 18 receives operation from the operation terminal 19 of the user who uses hot water from the hot water tap 6, switches the first switching valve 8a to the auxiliary hot water outlet passage 10 side, and drives the hot water storage pump 7. The hot water sent to the hot water outlet passage 12 is taken out from the open hot water tap 6 via the connecting passage 15 and the auxiliary heat source unit 5, as shown by the arrow HW.

When the user has drawn the required amount of hot water, he or she stops the hot water storage pump 7 by operating the operation terminal 19. If the user closes the hot water tap 6 and the flow rate detected by the hot water outlet flow rate sensor 12a falls below a preset reference flow rate, the hot water storage unit control unit 18 may stop the hot water storage pump 7.

Next, a case where the hot water stored in the hot water storage tank 2 is utilized when various operations such as hot water storage operation and hot water supply operation are not performed will be described with reference to Fig. 3. The flow of the hot water is indicated by arrows shown in the passage.
When the outside air temperature drops below a predetermined temperature, the hot water storage and supply system 1 performs a freeze prevention operation, for example, by periodically circulating hot water between the hot water storage tank 2 and the heat source unit 4 at a predetermined time interval. In addition, since the hot water storage and supply system 1 is equipped with the first switching valve 8a and the auxiliary hot water outlet passage 10, when hot water is not circulating between the hot water storage tank 2 and the heat source unit 4, the hot water in the hot water storage tank 2 is circulated periodically at a predetermined time interval via the auxiliary hot water outlet passage 10.

When the first switching valve 8a is switched to the auxiliary hot water outlet passage 10 side and the hot water storage pump 7 is driven, hot water is sent from the bottom of the hot water storage tank 2 to the mixing valve 14 via the heat source supply passage 8 and the auxiliary hot water outlet passage 10. Because the hot water tap 6 is closed, the hot water does not flow to the connecting passage 15 side, and is separated into hot water that returns to the top of the hot water storage tank 2 at the mixing valve 14 and hot water that returns to the bottom of the hot water storage tank 2 via the water supply branch passage 11a and the water supply passage 11.

By circulating the hot water in the hot water storage tank 2 in this way, it is possible to prevent the hot water from freezing without using anti-freeze heaters installed in each passage. Anti-freeze heaters in passages through which hot water can circulate may be omitted. Note that passages through which hot water cannot circulate, such as the upstream portion of the branch of the water supply branch passage 11a of the water supply passage 11 and the downstream portion of the connection of the hot water outlet passage 12 with the auxiliary hot water outlet passage 10, are heated by the installed anti-freeze heaters.

Next, a case where hot water stored in the hot water storage tank 2 is supplied to the hot water outlet passage 12 via the auxiliary hot water outlet passage 10 when the hot water stored in the hot water storage tank 2 is used for hot water supply will be described with reference to Fig. 4. The flow of hot water is indicated by arrows in the passage.
Hot water at a temperature equal to or higher than a preset reference temperature (e.g., 50° C.) is stored in the hot water storage tank 2 by hot water storage operation, and this hot water is supplied from the hot water tap 6. The reference temperature is set so that short-term contact will not cause burns.

At this time, the hot water storage unit control unit 18 sets the mixing ratio in the mixing valve 14 based on the temperature detected by the hot water storage tank outlet temperature sensor 12b and the water supply temperature, adjusts the opening of the mixing valve 14 so that the outlet temperature becomes the hot water supply set temperature (e.g., 40°C), and dispenses hot water from the hot water storage unit 3. Then, it further adjusts the opening of the mixing valve 14 during hot water dispense so that the outlet temperature becomes the hot water supply set temperature (e.g., 40°C).

For example, if a malfunction occurs in the mixing valve 14 and the clean water is not mixed, and hot water in the hot water storage tank 2 is discharged from the hot water storage unit 3 while still at or above the reference temperature, the auxiliary heat source unit 5 cannot take any measures to lower the temperature of this hot water, so the hot water is supplied directly to the hot water tap 6. Therefore, when the hot water outlet temperature becomes equal to or above the reference temperature, the hot water storage unit control unit 18 switches the first switching valve 8a to the auxiliary hot water outlet passage 10 side and drives the hot water storage pump 7, thereby supplying hot water from the lower part of the hot water storage tank 2 to the hot water outlet passage 12.

Low temperature hot water is usually stored in the lower part of the hot water storage tank 2, and clean water flows in from the water supply passage 11 in an amount equal to the amount of tap water. Therefore, the low temperature hot water in the lower part of the hot water storage tank 2 is supplied to the tap water passage 12 via the heat source machine supply passage 8 and the auxiliary hot water outlet passage 10. As a result, the low temperature hot water is mixed with hot water at a temperature above the reference temperature in the tap water passage 12, preventing hot water at a temperature above the reference temperature from being discharged, improving safety. Also, in order to increase the supply pressure to the hot water tap 6 when the water supply pressure of the clean water is low, the driving speed of the hot water storage pump 7 may be adjusted to supply hot water whose temperature has been adjusted in the tap water outlet passage 12 to the hot water tap 6.

The operation and effects of the above-described hot water storage and supply system 1 will now be described.
In the hot water storage and hot water supply system 1, an auxiliary hot water outlet passage 10 branched off from a heat source unit supply passage 8 (hot water storage passage) by a first switching valve 8a (flow path switching valve) between the hot water storage pump 7 and the heat source unit 4 is connected to a portion of the hot water outlet passage 12 downstream of a mixing valve 14. Therefore, hot water can be supplied from the bottom of the hot water storage tank 2 to the hot water outlet passage 12 via the auxiliary hot water outlet passage 10, so that hot water stored in the hot water storage tank 2 can be conveniently supplied to the hot water tap 6 that is normally used when the water supply is cut off.

At this time, the hot water storage unit control unit 18 (control means) switches the first switching valve 8a to the auxiliary hot water outlet passage 10 side and drives the hot water storage pump 7, so that hot water in the hot water storage tank 2 can be used via the auxiliary hot water outlet passage 10. Therefore, when there is a water outage, the hot water stored in the hot water storage tank 2 can be supplied to the hot water tap 6. Even if there is no water outage, when hot water storage operation and hot water outlet are not being performed, the hot water in the hot water storage tank 2 can be circulated to prevent the passages of the hot water storage and hot water supply system 1 from freezing.

When hot water in the hot water storage tank 2 is being discharged from the hot water storage unit 3 via the auxiliary hot water outlet passage 10, the hot water storage pump 7 is stopped if the flow rate of the hot water discharged from the hot water outlet passage 12 falls below the reference flow rate. Therefore, hot water stored in the hot water storage tank 2 is supplied to the hot water tap 6 during a water outage, and the hot water storage pump 7 can be stopped when the hot water storage tank 2 becomes empty or when the user closes the hot water tap 6. This prevents wear and failure of the hot water storage pump 7 and water leakage due to an increase in pressure in the passage to the hot water tap 6. Note that when the hot water in the hot water storage tank 2 is circulating, the hot water outlet flow rate is zero from the beginning, so the hot water storage unit control unit 18 stops the circulation based on the circulation time, for example.

When tap water is mixed with hot water from the hot water storage tank 2 by the mixing valve 14 for normal hot water supply without going through the auxiliary hot water outlet passage 10, if the temperature of the hot water discharged from the hot water outlet passage 12 is equal to or higher than the reference temperature, the first switching valve 8a is switched to the auxiliary hot water outlet passage 10 side and the hot water storage pump 7 is driven. Therefore, by mixing low-temperature hot water from the bottom of the hot water storage tank 2 through the auxiliary hot water outlet passage 10, it is possible to prevent high-temperature hot water above the reference temperature from being discharged due to, for example, a malfunction of the mixing valve 14, and the safety of the hot water storage and hot water supply system 1 is improved.

In addition, those skilled in the art can implement the above-described embodiments in various modified forms without departing from the spirit of the present invention, and the present invention includes such modified forms.

1: Hot water storage and hot water supply system 2: Hot water storage tanks 2a to 2d: Hot water storage temperature sensor 3: Hot water storage unit 4: Heat source unit 5: Auxiliary heat source unit 5a: Water inlet 5b: Hot water supply port 5c: Inlet water temperature sensor 5d: Hot water supply temperature sensor 5e: Hot water supply flow rate sensor 6: Hot water supply tap 7: Hot water storage pump 8: Heat source unit forward passage (hot water storage passage)
8a: First switching valve (flow path switching valve)
9: Heat source unit return passage 9a: Second switching valve 9b: Return branch passage 10: Auxiliary hot water outlet passage 11: Water supply passage 11a: Water supply branch passage 11b: Water supply temperature sensor 11c: Drain passage 11d: Overflow passage 11e: Drain plug 11f: Relief valve 12: Hot water outlet passage 12a: Hot water outlet flow rate sensor (flow rate detection means)
12b: Hot water storage tank outlet temperature sensor 12c: Outlet water temperature sensor (hot water temperature detection means)
14: Mixing valve 15: Connection passage 16: Hot water supply passage 18: Hot water storage unit control section (control means)
19: Operation terminal

Claims (4)

A hot water supply system having a heat source device, a hot water storage tank for storing hot water heated by a hot water storage operation of the heat source device, a hot water outlet passage for outletting the hot water in the upper part of the hot water storage tank, and a control means for controlling the hot water storage operation,
a mixing valve provided in the hot water outlet passage for mixing the hot water from the hot water storage tank with tap water;
A hot water storage passage equipped with a hot water storage pump that sends hot water from the lower part of the hot water storage tank to the heat source device during the hot water storage operation;
A flow path switching valve provided between the hot water storage pump and the heat source device in the hot water storage passage;
A hot water storage and hot water supply system comprising: an auxiliary hot water outlet passage that is branched off from the hot water storage passage by the flow path switching valve and is connected to a portion of the hot water outlet passage downstream of the mixing valve. The hot water storage and hot water supply system according to claim 1, characterized in that the control means is configured to supply hot water from the hot water storage tank to the hot water outlet passage by switching the flow path switching valve to the auxiliary hot water outlet passage side and driving the hot water storage pump. a flow rate detection means is provided in a downstream portion of the hot water outlet passage from the connection portion of the auxiliary hot water outlet passage,
The hot water storage and hot water supply system of claim 2, characterized in that the control means stops the hot water storage pump when the flow rate detected by the flow detection means falls below a predetermined reference flow rate while the hot water storage pump is operating. A hot water temperature detection means is provided in a downstream portion of the hot water outlet passage from the connection portion with the auxiliary hot water outlet passage,
The hot water storage and hot water supply system of claim 1, characterized in that when the hot water temperature detection means detects a temperature higher than a predetermined reference temperature when hot water is discharged from the top of the hot water storage tank, the control means switches the flow path switching valve to the auxiliary hot water discharge passage side and drives the hot water storage pump.

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