JP2024111408A - Storage tank type hot water supply device - Google Patents

Abstract

[Problem] To provide a storage type hot water supply device that can prevent freezing of a heating bypass pipe with an inexpensive configuration and can maintain a safe pressure inside the storage type hot water supply device by discharging hot water at a relatively low temperature from a pressure relief valve 38. [Solution] The storage type hot water supply device includes a hot water storage tank 2 that stores hot water, a heating means 16 that heats hot water in the storage tank 2, a heating supply pipe 17 that sends hot water from the lower part of the storage tank 2 to the heating means 16, a circulation pump 20 provided midway along the heating supply pipe 17, a heating return pipe 18 that sends hot water heated by the heating means 16 to the upper part of the hot water storage tank 2, a heating bypass path that branches off from the heating return pipe 18 and merges with a water supply pipe 4, a heating bypass valve 22 that switches the flow of hot water from the heating return pipe 18 to the heating bypass path, and a pressure relief valve 38 that releases pressure outside the storage type hot water supply device when the pressure inside the storage type hot water supply device exceeds a predetermined pressure, and the pressure relief valve 38 is provided in the heating bypass path. [Selected figure] Figure 3

Description

This invention relates to a storage-type hot water supply device with a heating means.

Conventionally, this type of storage-type hot water supply device has been equipped with a hot water storage tank and a heating means, and a heating circulation circuit has been formed by connecting the hot water storage tank and the heating means with a heating forward pipe that sends water from the bottom of the hot water storage tank to the heating means and a heating return pipe that sends water from the heating means to the hot water storage tank. A circulation pump installed in the heating circulation circuit circulates hot water in the hot water storage tank and the heating means, and the hot water boiled during the boiling operation that heats the water in the hot water storage tank is stored in the hot water storage tank. Hot water is supplied at the set temperature while the high-temperature water in the hot water storage tank is mixed with the supply water in sequence, realizing economical hot water supply.

In addition, there is a hot water storage type hot water supply device in which a heating bypass pipe branching off from the heating return pipe is connected to a water supply pipe, and a bypass circulation path passing through the heating bypass pipe shares part of the water supply path of the water supply pipe. In order to prevent freezing of the water supply pipe and the heating bypass pipe, a freeze prevention operation is known in which hot water is circulated to the heating bypass pipe side during boiling operation and flows into the lower part of the hot water storage tank (for example, Patent Document 1).

It was also known that by locating a pressure relief valve, which opens when the pressure inside the storage type hot water supply device exceeds a predetermined pressure, in a position where low-temperature water flows, low-temperature water is discharged when the pressure is released outside the storage type hot water supply device, thereby preventing high-temperature water stored in the hot water storage tank from being discharged outside the storage type hot water supply device (for example, Patent Document 2).

JP 2007-139258 A JP 2013-217622 A

However, as in Patent Document 1, when high-temperature water boiled by the heat pump heating means is circulated to the heating bypass pipe side and flows into the bottom of the hot water storage tank for anti-freezing operation during boiling operation, there is a problem that the high-temperature water accumulates at the bottom of the hot water storage tank, causing the inlet water temperature flowing into the heat pump heating means to rise, reducing the boiling efficiency.

In addition, by locating a pressure relief valve in the water supply pipe as in Patent Document 2, it is possible to prevent high-temperature water from being discharged from the hot water tank. However, in a hot water storage type hot water supply device equipped with a heating bypass pipe, when pressure is released by the pressure relief valve during boiling operation, no flow of hot water is generated in the heating bypass pipe, and there is a possibility that the pipe may freeze unless anti-freeze operation as in Patent Document 1 is performed.

According to the present invention, a hot water storage type hot water supply device includes a hot water storage tank for storing hot water, a heating means for heating the hot water in the hot water storage tank, a hot water outlet pipe connected to the upper part of the hot water storage tank, a water supply pipe connected to the lower part of the hot water storage tank, a water supply bypass pipe branching off from the water supply pipe and joining the hot water outlet pipe, a hot water supply pipe for mixing the high-temperature water in the hot water outlet pipe with the supply water in the water supply bypass pipe and delivering the hot water to a hot water supply destination, a heating supply pipe for delivering the hot water from the lower part of the hot water storage tank to the heating means, and The system includes a circulation pump provided midway through the supply pipe, a heating return pipe that sends hot water heated by the heating means to the top of the hot water storage tank, a heating bypass path that branches off from the heating return pipe and merges with the water supply pipe, a heating bypass valve that switches the flow of the hot water from the heating return pipe to the heating bypass path, and a pressure relief valve that releases pressure outside the storage type hot water supply device when the pressure inside the storage type hot water supply device exceeds a predetermined pressure, and the pressure relief valve is provided in the heating bypass path.

The pressure relief valve is located closer to the inlet side branching position where the heating bypass path branches off from the heating return pipe than to the outlet side junction position where the heating bypass path joins the water supply pipe.

This invention makes it possible to prevent freezing of the heating bypass pipe with an inexpensive configuration, and by discharging relatively low-temperature hot water from the pressure relief valve, it is possible to maintain a safe pressure inside the hot water storage type hot water supply device.

1 is a schematic configuration diagram showing an embodiment of the present invention. 4 is a flowchart showing the operation of the heating operation of the present invention. FIG. 2 is a schematic diagram showing the arrangement of a pressure relief valve according to an embodiment of the present invention.

Next, a storage type hot water supply device according to one embodiment of the present invention will be described with reference to the drawings.
Reference numeral 1 denotes the hot water storage tank unit, which includes a hot water storage tank 2 for storing hot water, a hot water outlet pipe 3 connected to the upper part of the hot water storage tank 2, a water supply pipe 4 connected to the lower part of the hot water storage tank 2, a hot water mixing valve 6 for mixing high temperature water from the hot water outlet pipe 3 with low temperature water from a water supply bypass pipe 5 branching off from the water supply pipe 4, and a hot water temperature sensor 8 and a hot water flow sensor 9 for detecting the hot water flow rate, which are provided in a hot water pipe 7 connected downstream of the hot water mixing valve 6.

10 is a heat pump unit, which is equipped with a heat pump type heating means 16 consisting of a compressor 11, a water-refrigerant heat exchanger 12 as a condenser, an electronic expansion valve 13, an outdoor fan 14, and an air heat exchanger 15 as an evaporator that exchanges heat with air, a circulation pump 20 that circulates the hot water in the hot water storage tank 2 to the heating means 16 via a heating circulation circuit 19 consisting of a heating forward pipe 17 and a heating return pipe 18, and a heat pump control unit 21 that controls the operation of these, and carbon dioxide is used as a refrigerant in the heating means 16 to form a supercritical heat pump cycle. In addition, because carbon dioxide is used as the refrigerant, it is possible to boil low-temperature water to a high temperature of about 90°C without an electric heater.

The water-refrigerant heat exchanger 12 employs a counterflow system in which the refrigerant and the hot water in the hot water storage tank 2, which is the water to be heated, flow in opposite directions. In a supercritical heat pump cycle, the refrigerant is condensed while remaining in a supercritical state during heat exchange, so the water to be heated can be heated to a high temperature efficiently. By controlling the expansion valve 13 or compressor 11 so that the temperature difference between the inlet temperature of the water-refrigerant heat exchanger 12 for the heated water and the outlet temperature of the refrigerant is constant, it is possible to heat the heated water with a very good COP (coefficient of performance) when the inlet temperature of the water-refrigerant heat exchanger 12 for the heated water is a low temperature of around 5 to 20°C.

A heating bypass valve 22 is provided midway through the heating return pipe 18, and when freezing prevention is required, the heating bypass valve 22 is switched to communicate with the heating bypass pipe 23, which is a heating bypass route connected to the water supply pipe 4 at the bottom of the hot water storage tank 2, to prevent freezing by circulating a short circuit using the bottom of the hot water storage tank 2. This heating bypass valve 22 is located at the branch point from the heating return pipe 18 to the heating bypass pipe 23.

In addition, when circulating hot water that is not sufficiently heated at the beginning of heating by the heating means 16, the hot water is not returned to the top of the hot water storage tank 2, but is returned to the bottom of the hot water storage tank 2 via a bypass circulation path via the heating bypass pipe 23, and when circulating hot water that is sufficiently heated thereafter, the heating bypass valve 22 is switched to the top side of the hot water storage tank 2.

24 is a control device consisting of a microcomputer, etc., which controls the heat pump control unit 21 to perform operations such as heating and reheating the hot water storage tank 2 using the heating circulation circuit 19, controlling the hot water temperature, filling the bathtub with water, reheating the bathtub, and keeping the bathtub warm.

The control device 24 also includes a heating bypass valve control means 25 that controls the opening degree of the heating bypass valve 22. Specifically, the heating bypass valve control means 25 switches between a first state in which the heating bypass valve 22 is switched to the heating bypass pipe 23 side and communicates with the water supply pipe 4 at the bottom of the hot water storage tank 2, and a second state in which the heating bypass valve 22 communicates with the upper side of the hot water storage tank 2.

The control device 24 also includes a rotation speed control means 26 that controls the rotation speed of the circulation pump, and a boiling operation control means 27 that controls the boiling operation described below.

At the start of this boiling operation, the refrigerant in the heating means 16 is not heated sufficiently, and the water in the lower part of the hot water storage tank 2 flowing in from the heating forward pipe 17 cannot be boiled to the boiling target temperature, so the rotation speed control means 26 sets the rotation speed of the circulation pump 20 to less than a predetermined rotation speed (this rotation speed less than the predetermined rotation speed refers to a low rotation speed state, and will be referred to as the low rotation speed state in the text below), and the boiling operation control means 27 drives the circulation pump 20 to perform the boiling operation, and when the elapsed time from the start of the boiling operation, which is the end condition of the low rotation speed state, is more than a predetermined time, or the outlet temperature sensor 35 in the heating return pipe 18 reaches a predetermined temperature or more, the rotation speed control means 26 sets the rotation speed of the circulation pump 20 to a predetermined boiling rotation speed and performs the boiling operation. The predetermined rotation speed here is higher than the low rotation speed state and lower than the predetermined boiling rotation speed, and is at least a rotation speed at which the circulation of the boiling operation does not stop due to the influence of the water supply pressure due to the hot water supply.

As described above, when the boiling operation starts, the refrigerant in the heating means 16 is not sufficiently heated, and the water in the lower part of the hot water storage tank 2 that flows in from the heating supply pipe 17 cannot be boiled up to the target temperature. Therefore, the heating bypass valve control means 25 sets the heating bypass valve 22 to the first state, performs boiling, and returns the boiled water to the lower part of the hot water storage tank 2. Then, when the end condition of the low rotation state is reached, the heating bypass valve 22 is set to the second state and boiling operation is performed.

The remote control 28 also has a temperature setting switch 29 for setting the hot water supply temperature, a water filling switch 30 for instructing the bath to be filled with water, and a water filling amount setting switch 31. It also has a display unit 32 consisting of a dot matrix fluorescent display tube, and a remote control control unit 33 consisting of a microcomputer that controls the display unit 32 and communicates with the control device 24.

In addition, the water-refrigerant heat exchanger 12 of the heating circulation circuit 19 is provided with an inlet water temperature sensor 34 on the water inlet side to detect the inlet water temperature, and an outlet temperature sensor 35 on the outlet side to detect the hot water temperature after heating. The hot water storage tank 2 is provided with a plurality of hot water temperature sensors 36 for detecting the hot water temperature in the hot water storage tank 2, and the lower hot water storage temperature sensor 36 terminates the boiling operation by continuously detecting the boiling target temperature. In addition, in the embodiment, the boiling operation is terminated when the hot water storage temperature sensor 36 continuously detects the boiling target temperature, but the amount of hot water storage may be calculated from the hot water temperature detected by the hot water storage temperature sensor 36, and the boiling operation may be terminated when the target hot water storage amount is reached during the boiling operation.

37 is a pressure reducing valve installed in the water supply pipe 4.

38 is a pressure relief valve installed in the heating bypass pipe 23 to release pressure within the hot water storage tank 2 and the heating circulation circuit 19.

This pressure relief valve 38 opens when the hot water in the hot water storage tank 2 and the heating circulation circuit 19 becomes hot during heating operation, causing the pressure in the hot water storage type hot water supply system to rise and exceed a certain pressure, allowing the hot water and pressure to be discharged outside the hot water storage type hot water supply system.

39 is a bath filling valve that connects the bathtub filling pipe 40 to the bathtub and supplies hot water to the bathtub, 41 is a bath temperature sensor that detects the bath temperature supplied to the bath, and 42 is a bath flow sensor that detects the flow rate passing through the bathtub filling pipe 40.

Next, the boiling operation will be described.
When there is a decrease in the heat energy of the stored hot water or a request for heating during the middle of the night, the heating bypass valve control means 25 switches the heating bypass valve 22 to a first state in which it connects to the lower side of the hot water storage tank 1, and the control device 24 drives the circulation pump 20 located in the middle of the piping connecting the hot water storage tank 2 and the heating means 16 to draw water from the lower part of the hot water storage tank 2, heat it in the heating means 16, and return it to the lower part of the hot water storage tank 32, and then, when the end condition of the low rotation state is reached, it switches to a second state in which it connects to the upper side of the hot water storage tank 2, and by continuing the operation of returning the water to the upper part of the hot water storage tank 2, the water in the hot water storage tank 2 is gradually boiled into high-temperature water.

Next, the operation of the embodiment when hot water supply operation is performed during boiling operation will be described in detail with reference to the flow chart of FIG.
When there is a decrease in the heat energy of the stored hot water or a request for heating during the middle of the night and the heating operation control means 27 starts heating operation (S1 is Yes), the heating bypass valve control means 25 sets the heating bypass valve 22 to the first state in which it connects to the heating bypass pipe 23 side (S2), the rotation speed control means 26 sets the rotation speed of the circulation pump 20 to the low rotation speed state (less than a specified rotation speed) (S3), and the heating operation control means 27 drives the circulation pump 20.

When the end condition for the low rotation state is met (Yes in S4), the heating bypass valve control means 25 sets the heating bypass valve 22 to a second state in which it is connected to the upper side of the hot water storage tank 2 (S5), the rotation speed control means 26 sets the rotation speed of the circulation pump 20 to a predetermined boiling rotation speed (S6), and the boiling operation control means 27 continues the boiling operation.

After that, the lower hot water storage temperature sensor 36 continues to detect the target boiling temperature (S7: Yes), and the boiling operation is completed (S8).

By performing the boiling operation, the water in the storage type hot water supply device becomes hot and the pressure inside the storage type hot water supply device rises, so during boiling operation, hot water and pressure are discharged outside the storage type hot water supply device through the pressure relief valve 38.

Next, the hot water supply operation will be described.
When the hot water tap is opened, water is supplied from the water supply pipe 4, flows into the lower part of the hot water storage tank 2 and passes through the water supply bypass pipe 5. The high-temperature water pushed out from the upper part of the hot water storage tank 2 and the water supply from the water supply bypass pipe 5 are mixed in the hot water mixing valve 6, and hot water adjusted so that the hot water setting temperature and the temperature detected by the hot water temperature sensor 8 are the same is supplied from the hot water tap.

The filling operation will also be described.
When the filling switch 30 on the remote control 28 is pressed, the control device 24 opens the filling valve 39, supplies water from the water supply pipe 4, and the water flows into the bottom of the hot water storage tank 2 and passes through the water supply bypass pipe 5. The high-temperature water pushed out from the top of the hot water storage tank 2 and the water supply from the water supply bypass pipe 5 are mixed in the hot water supply mixing valve 6, and filling of the bath begins when the hot water is adjusted so that the bath set temperature and the temperature detected by the bath temperature sensor 41 are the same and flow into the bathtub. The bath flow sensor 42 detects the flow rate, and when the total accumulated value of the flow rate reaches the set filling amount, the control device 24 closes the filling valve 39, completing filling of the bath.

Next, the detailed arrangement of the pressure relief valve 38 will be described with reference to FIGS.
The position where the heating bypass valve 22 provided in the heating return pipe 18 branches off to the heating bypass pipe 23 is referred to as the inlet side branching position a, and the position where the heating bypass pipe 23 joins the water supply pipe 4 is referred to as the outlet side joining position b.

A pressure relief valve 38 is placed in the middle of the heating bypass pipe 23, with the inlet branch position a on the upstream side and the outlet junction position b on the downstream side.

The flow of hot and cold water when a pressure relief valve 38 is arranged in the heating bypass pipe 23 will be described.
When the pressure inside the storage type water heater rises and the pressure relief valve 38 is opened, if the heating bypass valve 22 is in the second state, no flow of hot water occurs between the inlet side branch position a and the pressure relief valve 38, but the hot water between the pressure relief valve 38 and the outlet side junction position b is discharged outside the storage type water heater together with the pressure.

Then, as the hot water between the pressure relief valve 38 and the outlet-side junction position b is discharged, water is first supplied from the water supply pipe 4 near the outlet-side junction position b. At this time, if the pressure inside the storage-type hot water supply device exceeds a predetermined pressure, the water supplied from the water supply pipe 4 is discharged outside the storage-type hot water supply device together with the pressure. This supply of water from the water supply pipe 4 continues until the pressure inside the storage-type hot water supply device falls below the predetermined pressure, preventing a pressure rise inside the storage-type hot water supply device and generating a flow of hot water in the heating bypass pipe 23.

When the hot water between the pressure relief valve 38 and the outlet-side junction position b is discharged and water is supplied from the water supply pipe 4 near the outlet-side junction position b, the hot water in the hot water storage tank 2 expands due to the high temperature inside the hot water storage tank 2, and is discharged outside the hot water storage type hot water supply device together with the pressure through the water supply pipe 4. This supply of hot water from the hot water storage tank 2 continues until the pressure inside the hot water storage tank 2 falls below a predetermined pressure, preventing damage to the hot water storage tank 2 and generating a flow of hot water in the heating bypass pipe 23.

In this way, since the pressure relief valve 38 is located midway through the heating bypass pipe 23, if the pressure in the storage type hot water supply system including the hot water storage tank 2 exceeds a predetermined pressure, the pressure is discharged from the pressure relief valve 38 to the outside of the storage type hot water supply system together with the hot water in the heating bypass pipe 23 and the relatively low-temperature hot water in the water supply pipe 4. This prevents high-temperature water from being discharged and consuming heat, and provides a safe, low-cost storage type hot water supply system.

In addition, during boiling operation, the temperature detected by the outlet temperature sensor 35 rises, so the heating bypass valve 22 does not switch to the heating bypass pipe 23 side that flows into the lower part of the hot water storage tank 2, and so the hot water in the heating bypass pipe 23 does not move, and there is a possibility that the heating bypass pipe 23 will freeze. However, since the boiling operation also increases the pressure in the storage-type hot water supply device, opening the pressure relief valve 38 creates a flow of hot water in the heating bypass pipe 23, preventing freezing.

In addition, since a flow of hot water is generated in the heating bypass pipe 23 as the pressure rises during the boiling operation, it is possible to prevent freezing of the heating bypass pipe 23 with an inexpensive configuration without circulating hot water in the lower part of the hot water storage tank 2 or using an electric heater or the like to heat the heating bypass pipe 23.

In addition, by providing a pressure relief valve 38 in the middle of the heating bypass valve 22, it is not necessary to switch the heating bypass valve 22 to the heating bypass pipe 23 side during boiling operation, so there is no need to raise the temperature at the bottom of the hot water storage tank 2, and the decrease in boiling efficiency can be suppressed.

Next, we will explain the case where the pressure relief valve 38 is placed closer to the inlet branch position a than to the outlet junction position b in the heating bypass pipe 23, where the inlet branch position a is on the upstream side and the outlet junction position b is on the downstream side. Preferably, the closer to the inlet branch position a, the better.

In this way, the closer the pressure relief valve 38 is to the inlet branch position a, the longer the length between the outlet junction position b in the heating bypass pipe 23 and the pressure relief valve 38, so the length of hot water movement is longer, generating a large flow of hot water and preventing freezing from the pressure relief valve 38 to the outlet junction position b.

In addition, if the distance between the inlet branch position a and the pressure relief valve 38 is short, the high-temperature water is heated by passing through the heating bypass valve 22 during boiling operation, and the heat released can prevent freezing near the inlet branch position a.

The present invention is not limited to the embodiments, and modifications may be made without changing the gist of the invention. For example, in the embodiments, a pressure relief valve 38 is provided in the heating bypass pipe 23, but the pressure relief valve 38 may be provided directly between the heating bypass valve 22 and the water supply pipe 4 without providing a heating bypass pipe 23.

2 hot water storage tank 3 hot water outlet pipe 4 water supply pipe 5 water supply bypass pipe 6 hot water supply mixing valve 7 hot water supply pipe 16 heating means 19 heating circulation circuit 20 circulation pump 22 heating bypass valve 23 heating bypass pipe (heating bypass path)
24 Control device 25 Heating bypass valve control means 26 Rotation speed control means 27 Boiling operation control means 38 Pressure relief valve a Inlet side branching position b Outlet side joining position

Claims (2)

Storage type hot water heaters are
A hot water storage tank for storing hot water;
A heating means for heating the hot water in the hot water storage tank;
A hot water outlet pipe connected to an upper portion of the hot water storage tank;
A water supply pipe connected to a lower portion of the hot water storage tank;
A water supply bypass pipe that branches off from the water supply pipe and joins the hot water outlet pipe; a hot water supply pipe that mixes the high-temperature water from the hot water outlet pipe with the supply water from the water supply bypass pipe and delivers the hot water to a hot water supply destination;
A heating pipe that sends the hot water from a lower part of the hot water storage tank to the heating means;
A circulation pump provided in the heating supply pipe;
A heating return pipe that sends the hot water heated by the heating means to an upper portion of the hot water storage tank;
A heating bypass path that branches off from the heating return pipe and merges with the water supply pipe;
a heating bypass valve for switching the flow of the hot water from the heating return pipe to the heating bypass path;
a pressure relief valve that releases pressure to the outside of the storage type hot water supply device when the pressure in the storage type hot water supply device exceeds a predetermined pressure;
The storage type hot water supply device is characterized in that the pressure relief valve is provided in the heating bypass path. The hot water storage type hot water supply device according to claim 1, characterized in that the pressure relief valve is provided at a position closer to an inlet side branching position where the heating bypass path branches off from the heating return pipe than to an outlet side junction position where the heating bypass path joins the water supply pipe.

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