Hot water storage type water heater

Abstract

To provide a hot water storage type water heater capable of circulating highly concentrated fine bubbles, enhancing the effect of inhibiting scale adhesion, and having excellent energy saving.SOLUTION: A hot water storage type water heater is provided with fine bubble generation means 43 in a circulation circuit 40. Control means 70 has: a boiling operation mode in which a downstream end of the circulation circuit 40 is switched to an upper connection port 33 of a hot water storage tank 30 by flow path switching means 41, and heating operation is performed by heating means 2; and a scale adhesion inhibition operation mode in which the downstream end of the circulation circuit 40 is switched to a lower connection port 34 of the hot water storage tank 30 by the flow path switching means 41, and hot water in the hot water storage tank 30 is circulated by a circulation pump 42. At least in the scale adhesion inhibition operation mode, fine bubbles generated by the fine bubble generation means 43 are guided to the hot water storage tank 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a storage type hot water heater equipped with a hot water storage tank. [Background technology]

[0002] The hot water storage type water heater of Patent Document 1 includes a hot water storage tank, a refrigerant circuit connected to a water heat exchanger for heating water by heat exchange with a refrigerant, and a water circulation circuit that supplies water from the hot water storage tank to the water heat exchanger and returns water heated by the water heat exchanger to the hot water storage tank. The water circulation circuit is provided with a micro-bubble generating means that generates micro-bubbles by pressurizing and dissolving gas in water supplied from the hot water storage tank to the water heat exchanger and then reducing the pressure. As described in Non-Patent Document 1, the International Organization for Standardization (ISO) defines bubbles with a diameter of less than 100 μm as fine bubbles, of which bubbles with a diameter of 1 μm or more but less than 100 μm are defined as microbubbles, and bubbles with a diameter of less than 1 μm as ultrafine bubbles. The smaller the diameter of the fine bubbles, the longer they stay in water, and have physiologically active effects such as promoting blood flow and sterilizing bacteria, as well as being able to purify water, treat wastewater, and clean. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-150597 [Non-patent literature]

[0004] [Non-Patent Document 1] Katsumi Aoki, Katsunori Kato, Toshiya Okutsu, Naoya Shinohara, "Fundamental Principles of Fine Bubble Generation and Characteristics of Generators", Design Engineering, Journal of the Japan Society of Design Engineering, 2017, No. 52, No. 5, pp. 275-285 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the fine bubbles are always returned to the top of the hot water storage tank. Therefore, the concentration of the fine bubbles generated by the fine bubble generating means depends on the generation capacity of the fine bubble generating means itself. The concentration of the fine bubbles generated by the fine bubble generating means can be increased by increasing the amount of water circulated, but increasing the amount of water circulated increases the pressure loss. Furthermore, with the configuration of Patent Document 1, water is always guided to the microbubble generating means, which increases power consumption.

[0006] Therefore, the present invention aims to provide a storage-type water heater that can circulate high-concentration fine bubbles, enhance the effect of inhibiting scale buildup, and is highly energy-efficient. [Means for solving the problem]

[0007] The hot water storage type water heater of the present invention as set forth in claim 1 comprises a hot water storage tank 30 for storing hot water, heating means 2 for heating the hot water stored in the hot water storage tank 30, a circulation circuit 40 for guiding the hot water stored in the lower part of the hot water storage tank 30 to the heating means 2 and returning the hot water stored in the heating means 2 to the hot water storage tank 30, flow path switching means 41 provided in the circulation circuit 40, a circulation pump 42 provided in the circulation circuit 40, and control means 70 for performing a heating operation in the heating means 2 and a switching operation of the flow path switching means 41, and the flow path switching means 41 switches the downstream end of the circulation circuit 40 between an upper connection port 33 of the hot water storage tank 30 and a lower connection port 34 of the hot water storage tank 30. The water heater is provided with a fine bubble generating means 43 in the circulation circuit 40, and the control means 70 has a boiling operation mode in which the downstream end of the circulation circuit 40 is switched to the upper connection port 33 of the hot water storage tank 30 by the flow path switching means 41 and the heating operation is performed by the heating means 2, and a scale deposition prevention operation mode in which the downstream end of the circulation circuit 40 is switched to the lower connection port 34 of the hot water storage tank 30 by the flow path switching means 41 and the hot water in the hot water storage tank 30 is circulated by the circulation pump 42, and is characterized in that at least in the scale deposition prevention operation mode, the fine bubbles generated by the fine bubble generating means 43 are guided to the hot water storage tank 30. The storage type water heater of the present invention described in claim 2 is characterized in that, in the storage type water heater described in claim 1, the control means 70 changes the circulation volume of the circulation pump 42, making the circulation volume of the circulation pump 42 in the scale deposition suppression operation mode greater than the circulation volume of the circulation pump 42 in the boiling operation mode. The storage type water heater of the present invention described in claim 3 is characterized in that, in the storage type water heater described in claim 1, the control means 70 has an initial boiling operation mode in which the downstream end of the circulation circuit 40 is switched to the lower connection port 34 of the hot water storage tank 30 by the flow path switching means 41, and the heating operation is performed by the heating means 2, and the circulation amount in the circulation pump 42 is changed so that the circulation amount of the circulation pump 42 in the scale deposition prevention operation mode is greater than the circulation amount of the circulation pump 42 in the initial boiling operation mode. The storage type water heater of the present invention described in claim 4 is characterized in that, in the storage type water heater described in claim 1, the control means 70 has a pipe anti-freeze operation mode in which the downstream end of the circulation circuit 40 is switched to the lower connection port 34 of the hot water storage tank 30 by the flow path switching means 41, and anti-freeze operation of the pipes is performed, and the circulation amount in the circulation pump 42 is changed so that the circulation amount of the circulation pump 42 in the scale adhesion suppression operation mode is greater than the circulation amount of the circulation pump 42 in the pipe anti-freeze operation mode. The hot water storage type water heater of the present invention described in claim 5 is a hot water storage type water heater described in any one of claims 1 to 4, characterized in that the circulation circuit 40 has a fine bubble generation switching means 44 that switches whether or not the hot water storage water is led to the fine bubble generating means 43, and the control means 70 leads the hot water storage water to the fine bubble generating means 43 by switching the fine bubble generation switching means 44 in the scale adhesion suppression operation mode, and does not lead the hot water storage water to the fine bubble generating means 43 by switching the fine bubble generation switching means 44 in the boiling operation mode. The hot water storage type water heater of the present invention described in claim 6 is a hot water storage type water heater described in any one of claims 1 to 4, characterized in that the circulation circuit 40 has a fine bubble generation switching means 44 that switches whether or not the hot water storage water is led to the fine bubble generating means 43, and the control means 70 leads the hot water storage water to the fine bubble generating means 43 by switching the fine bubble generation switching means 44 in the scale adhesion suppression operation mode, and leads the hot water storage water intermittently to the fine bubble generating means 43 by switching the fine bubble generation switching means 44 in the boiling operation mode. The storage-type water heater of the present invention described in claim 7 is a storage-type water heater described in any one of claims 1, 2, and 4, characterized in that the circulation circuit 40 has a fine-bubble generation switching means 44 that switches whether or not the stored hot water is led to the fine-bubble generating means 43, and the control means 70 has an initial boiling operation mode in which the downstream end of the circulation circuit 40 is switched to the lower connection port 34 of the hot water storage tank 30 by the flow path switching means 41, and the heating operation is performed by the heating means 2, and in the scale adhesion suppression operation mode, the stored hot water is led to the fine-bubble generating means 43 by switching the fine-bubble generation switching means 44, and in the initial boiling operation mode, the stored hot water is not led to the fine-bubble generating means 43 by switching the fine-bubble generation switching means 44. The hot water storage type water heater of the present invention described in claim 8 is a hot water storage type water heater described in any one of claims 1 to 3, characterized in that the circulation circuit 40 has a fine bubble generation switching means 44 that switches whether or not the hot water storage water is led to the fine bubble generating means 43, and the control means 70 has a pipe anti-freeze operation mode in which the downstream end of the circulation circuit 40 is switched to the lower connection port 34 of the hot water storage tank 30 by the flow path switching means 41, and performs pipe anti-freeze operation, and in the scale adhesion suppression operation mode, the hot water storage water is led to the fine bubble generating means 43 by switching the fine bubble generation switching means 44, and in the pipe anti-freeze operation mode, the hot water storage water is not led to the fine bubble generating means 43 by switching the fine bubble generation switching means 44. [Effects of the Invention]

[0008] According to the present invention, the hot water present at the bottom of the hot water storage tank can be led to a fine bubble generating means, and the hot water containing fine bubbles can be circulated while the downstream end of the circulation circuit is connected to the lower connection port, making it possible to operate in a scale deposition prevention operating mode without disrupting the layer of high-temperature water at the top of the hot water storage tank, thereby preventing a drop in the temperature of the high-temperature water at the top of the hot water storage tank and enhancing the scale deposition prevention effect. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram of a storage type hot water heater according to an embodiment of the present invention; [Figure 2] FIG. 1 is a configuration diagram of a storage type hot water heater according to another embodiment of the present invention. [Figure 3] FIG. 1 is a configuration diagram of a storage type hot water heater according to still another embodiment of the present invention. [Figure 4] FIG. 1 is a configuration diagram of a storage type hot water heater according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] In a first embodiment of the present invention, a hot water storage type water heater includes a circulation circuit provided with a micro-bubble generating means, and a control means for controlling the flow path switching means to switch the downstream end of the circulation circuit to the upper connection port of the hot water storage tank and perform heating operation using the heating means, and a scale deposition suppression operation mode for switching the downstream end of the circulation circuit to the lower connection port of the hot water storage tank and circulating hot water from the hot water storage tank using a circulation pump, and in at least the scale deposition suppression operation mode, micro-bubbles generated by the micro-bubble generating means are directed to the hot water storage tank. According to this embodiment, hot water present in the lower part of the hot water storage tank can be directed to the micro-bubble generating means, and the hot water containing micro-bubbles can be circulated with the downstream end of the circulation circuit connected to the lower connection port, enabling the scale deposition suppression operation mode to be performed without disrupting the accumulation of high-temperature water in the upper part of the hot water storage tank, thereby preventing a drop in the temperature of the high-temperature water in the upper part of the hot water storage tank and enhancing the effect of suppressing scale deposition.

[0011] In a second embodiment of the present invention, in the storage type hot water heater according to the first embodiment, the control means changes the circulation rate of the circulation pump so that the circulation rate of the circulation pump in the scale deposition prevention operation mode is greater than the circulation rate of the circulation pump in the boiling operation mode. According to this embodiment, it is possible to increase the amount of fine bubbles generated in the scale deposition prevention operation mode.

[0012] In a third embodiment of the present invention, in the storage type hot water heater according to the first embodiment, the control means has a boil-up initial operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the lower connection port of the hot water storage tank, performs heating operation using the heating means, and changes the circulation rate of the circulation pump so that the circulation rate of the circulation pump in the scale deposition prevention operation mode is greater than the circulation rate of the circulation pump in the boil-up initial operation mode. According to this embodiment, it is possible to increase the amount of fine bubbles generated in the scale deposition prevention operation mode.

[0013] In a fourth embodiment of the present invention, in the storage type hot water heater according to the first embodiment, the control means has a pipe freeze prevention operation mode in which the downstream end of the circulation circuit is switched to the lower connection port of the hot water storage tank by the flow path switching means, and the circulation rate of the circulation pump is changed so that the circulation rate of the circulation pump in the scale deposition prevention operation mode is greater than the circulation rate of the circulation pump in the pipe freeze prevention operation mode. According to this embodiment, the amount of fine bubbles generated in the scale deposition prevention operation mode can be increased.

[0014] In a fifth embodiment of the present invention, in the storage type hot water heater according to any one of the first to fourth embodiments, the circulation circuit has a fine bubble generation switching means for switching whether or not the stored hot water is led to the fine bubble generating means, and the control means switches the fine bubble generation switching means to lead the stored hot water to the fine bubble generating means in the scale adhesion suppression operation mode, and switches the fine bubble generation switching means to not lead the stored hot water to the fine bubble generating means in the boiling operation mode. According to this embodiment, pressure loss due to the fine bubble generating means in the boiling operation mode can be eliminated, and power consumption can be reduced.

[0015] In a sixth embodiment of the present invention, in the storage type water heater according to any one of the first to fourth embodiments, the circulation circuit has a fine bubble generation switching means for switching whether or not the stored hot water is led to the fine bubble generating means, and the control means leads the stored hot water to the fine bubble generating means by switching the fine bubble generation switching means in the scale adhesion suppression operation mode, and leads the stored hot water to the fine bubble generating means intermittently by switching the fine bubble generation switching means in the boiling operation mode. According to this embodiment, the pressure loss caused by the fine bubble generating means in the boiling operation mode can be reduced, thereby reducing power consumption.

[0016] A seventh embodiment of the present invention is a storage-type water heater according to any one of the first, second, and fourth embodiments, wherein the circulation circuit has a fine-bubble generation switching means for switching whether or not the stored hot water is led to the fine-bubble generating means, and the control means has an initial boiling operation mode in which the downstream end of the circulation circuit is switched to the lower connection port of the hot water storage tank by the flow path switching means and heating operation is performed by the heating means, and in the scale adhesion suppression operation mode, the fine-bubble generation switching means is switched to lead the stored hot water to the fine-bubble generating means, and in the initial boiling operation mode, the fine-bubble generation switching means is switched to not lead the stored hot water to the fine-bubble generating means. According to this embodiment, the pressure loss caused by the fine-bubble generating means in the initial boiling operation mode can be reduced, thereby reducing power consumption.

[0017] An eighth embodiment of the present invention is a hot water storage type water heater according to any one of the first to third embodiments, wherein the circulation circuit has a fine-bubble generation switching means for switching whether or not the hot water is led to the fine-bubble generating means, and the control means has a pipe freeze prevention operation mode for performing pipe freeze prevention operation by switching the downstream end of the circulation circuit to the lower connection port of the hot water storage tank by the flow path switching means, and in the scale adhesion prevention operation mode, the fine-bubble generation switching means is switched to lead the hot water to the fine-bubble generating means, and in the pipe freeze prevention operation mode, the fine-bubble generation switching means is switched to not lead the hot water to the fine-bubble generating means. According to this embodiment, the pressure loss due to the fine-bubble generating means in the pipe freeze prevention operation mode can be reduced, thereby reducing power consumption. [Example]

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a hot water storage type water heater according to this embodiment. The hot water storage type water heater of this embodiment is composed of a hot water storage tank unit 1 and heating means 2. The heating means 2 heats the hot water stored in the hot water storage tank 30 provided in the hot water storage tank unit 1. In this embodiment, a heat pump unit is used as the heating means 2 , and the heat pump unit 2 includes a heat pump circuit 20 . The heat pump circuit 20 includes a compressor 21 that compresses a refrigerant and discharges a high-temperature refrigerant, a water-refrigerant heat exchanger 22 that produces hot water by exchanging heat between water and the high-temperature refrigerant, a pressure reducing device 23 that reduces the pressure of the refrigerant, and an evaporator 24 that exchanges heat between air and the refrigerant, all of which are connected by refrigerant piping 25. The water-refrigerant heat exchanger 22 can be a plate-type heat exchanger or a double-pipe heat exchanger.

[0019] The hot water storage tank unit 1 includes a hot water storage tank 30 and a circulation circuit 40. The hot water storage tank 30 stores hot water, and the circulation circuit 40 guides the hot water present in the lower part of the hot water storage tank 30 to the heating means 2 and returns the hot water guided to the heating means 2 to the hot water storage tank 30. The hot water storage tank 30 is a layered boiling type, and during boiling operation, high-temperature water is layered in the upper part, low-temperature water in the lower part, and medium-temperature water in the middle part. A hot water outlet pipe 31 is connected to the top of the hot water storage tank 30, and a water supply pipe 32 is connected to the bottom of the hot water storage tank 30.

[0020] A hot water supply circuit 50 that supplies hot water stored in the hot water storage tank 30 connects the hot water outlet pipe 31 and the hot water tap 4 with a hot water supply pipe 51 . A hot water mixing valve 52 is provided on the hot water supply pipe 51. The hot water mixing valve 52 mixes high-temperature water from the hot water storage tank 30 with low-temperature water from the water supply pipe 32 to obtain the required hot water temperature.

[0021] A water supply circuit 60 that supplies water to the hot water storage tank 30 connects a water pipe 5 extending from a water supply source to the lower part of the hot water storage tank 30 via a water supply pipe 32. When the amount of hot water stored in the hot water storage tank 30 decreases, water is supplied to the hot water storage tank 30 from the water supply pipe 32. Furthermore, the required low-temperature water is supplied to the hot water mixing valve 52 from the water supply pipe 32. A hot water branch pipe 32a branched from the water supply pipe 32 and the hot water outlet pipe 31 are connected to the hot water mixing valve 52, and the mixed water flowing out of the hot water mixing valve 52 is guided to the hot water tap 4 by the hot water supply pipe 51.

[0022] The circulation circuit 40 is provided with a flow path switching means 41, a circulation pump 42, and a microbubble generating means 43. The circulation circuit 40 connects a circulation pump 42, a fine bubble generating means 43, a water-refrigerant heat exchanger 22, a flow path switching means 41, and a hot water storage tank 30 with piping. The flow path switching means 41 switches the downstream end of the circulation circuit 40 between the upper connection port 33 of the hot water storage tank 30 and the lower connection port 34 of the hot water storage tank 30 . The micro-bubble generating means 43 takes in gas through the flow of the hot water and generates micro-bubbles. In this embodiment, the fine bubble generating means 43 is disposed inside the hot water storage tank unit 1.

[0023] The upstream end of a circulation circuit 40 is connected to a lower connection port 34 of the hot water storage tank 30 . A drain pipe 35 is connected to a lower connection port 34 of the hot water storage tank 30. A drain plug 36 is provided on the drain pipe 35. The hot water stored in the hot water storage tank 30 can be drained through the drain pipe 35 by opening the drain plug 36. A pressure relief pipe 37 is connected to the hot water outlet pipe 31 or the upper part of the hot water storage tank 30. A pressure relief valve 38 is provided on the pressure relief pipe 37. When the pressure inside the hot water storage tank 30 exceeds a predetermined pressure, the pressure relief valve 38 is opened. By opening the pressure relief valve 38, the inside of the hot water storage tank 30 is connected to the atmosphere via the pressure relief pipe 37 and the drain pipe 35, and the pressure inside the hot water storage tank 30 can be reduced.

[0024] The hot water storage type water heater according to this embodiment has control means 70 which controls the heating operation of the heating means 2, the switching operation of the flow path switching means 41, and the change of the circulation amount of the circulation pump . The control means 70 has a boiling operation mode, a scale adhesion suppression operation mode, an initial boiling operation mode, and a pipe freeze prevention operation mode. In the boiling operation mode, the flow path switching means 41 switches the downstream end of the circulation circuit 40 to the upper connection port 33 of the hot water storage tank 30, and the heating means 2 performs heating operation. In the boiling operation mode, the circulation pump 42 is driven to send low-temperature water from the hot water storage tank 30 to the water-refrigerant heat exchanger 22, where heat is absorbed from the refrigerant to generate high-temperature water. The high-temperature water generated in the water-refrigerant heat exchanger 22 is returned to the hot water storage tank 30. The stored water guided from the hot water storage tank 30 to the water-refrigerant heat exchanger 22 contains fine bubbles generated by the fine-bubble generating means 43.

[0025] In the scale deposition prevention operation mode, the flow path switching means 41 switches the downstream end of the circulation circuit 40 to the lower connection port 34 of the hot water storage tank 30, and the hot water in the hot water storage tank 30 is circulated by the circulation pump 42. In the scale deposition prevention operation mode, it is preferable not to perform heating operation by the heating means 2, but heating operation may be performed. In the scale deposition prevention operation mode, the circulation pump 42 is driven to send low-temperature water from the hot water storage tank 30 to the water-refrigerant heat exchanger 22, and the stored water led to the water-refrigerant heat exchanger 22 is returned to the hot water storage tank 30 without being heated by the water-refrigerant heat exchanger 22. The stored water led from the hot water storage tank 30 to the water-refrigerant heat exchanger 22 contains fine bubbles generated by the fine bubble generating means 43, and the fine bubbles are led to the hot water storage tank 30.

[0026] In the initial boiling operation mode, the flow path switching means 41 switches the downstream end of the circulation circuit 40 to the lower connection port 34 of the hot water storage tank 30, and the heating means 2 performs heating operation. In the initial boiling operation mode, the circulation pump 42 is driven to send low-temperature water from the hot water storage tank 30 to the water-refrigerant heat exchanger 22, where heat is absorbed from the refrigerant to generate high-temperature water. The high-temperature water generated in the water-refrigerant heat exchanger 22 is returned to the hot water storage tank 30. The stored water guided from the hot water storage tank 30 to the water-refrigerant heat exchanger 22 contains fine bubbles generated by the fine-bubble generating means 43. The boiling initial operation mode is an operation mode from the start of the boiling operation until a predetermined period, and the operation mode transitions to the boiling initial operation mode after the boiling initial operation mode. In particular, when the heating means 2 is a heat pump unit, the refrigerant temperature in the water-refrigerant heat exchanger 22 does not rise sufficiently for a predetermined period of time after the start of operation, and the predetermined high-temperature water is not produced in the water-refrigerant heat exchanger 22. Therefore, by directing high-temperature water that has not yet reached the predetermined temperature to the bottom end of the hot water storage tank 30, a drop in the temperature of the high-temperature water in the upper part of the hot water storage tank 30 can be prevented.

[0027] In the pipe freeze prevention operation mode, the flow path switching means 41 switches the downstream end of the circulation circuit 40 to the lower connection port 34 of the hot water storage tank 30, and performs pipe freeze prevention operation. Here, the pipes to be protected from freezing are the lower pipes of the hot water storage tank 30, mainly the pipes connected to the lower connection port 33. The pipe freeze prevention operation mode has a heating pipe freeze prevention operation mode in which heating operation is performed by the heating means 2, and a heating non-pipe freeze prevention heating operation mode in which heating operation is not performed by the heating means 2. It is preferable to perform the heating pipe freeze prevention operation mode when the outside air temperature is below a predetermined temperature, and to perform the heating non-pipe freeze prevention operation mode when the outside air temperature exceeds the predetermined temperature. In addition, the hot water storage tank unit 1 or the heat pump unit (heating means) 2 is equipped with an outside air temperature detection sensor (not shown) to detect the outside air temperature. In this way, by having a pipe anti-freeze operation mode with heating and a pipe anti-freeze heating operation mode without heating, power consumption can be reduced and pipes can be efficiently prevented from freezing.

[0028] In the heating piped freeze prevention operation mode, the circulation pump 42 is driven to send low-temperature water from the hot water storage tank 30 to the water-refrigerant heat exchanger 22, where heat is absorbed from the refrigerant to produce high-temperature water. The high-temperature water produced in the water-refrigerant heat exchanger 22 is returned to the hot water storage tank 30. The stored water guided from the hot water storage tank 30 to the water-refrigerant heat exchanger 22 contains fine bubbles generated by the fine-bubble generating means 43.

[0029] In the heating no-pipe freeze prevention operation mode, the circulation pump 42 is driven to send low-temperature water from the hot water storage tank 30 to the water-refrigerant heat exchanger 22, and the stored water led to the water-refrigerant heat exchanger 22 is returned to the hot water storage tank 30 without being heated by the water-refrigerant heat exchanger 22. The stored water led from the hot water storage tank 30 to the water-refrigerant heat exchanger 22 contains fine bubbles generated by the fine bubble generating means 43, and the fine bubbles are led to the hot water storage tank 30.

[0030] In this way, at least in the scale adhesion prevention operation mode, the fine bubbles generated by the fine bubble generating means 43 are led to the hot water storage tank 30, and the hot water present at the bottom of the hot water storage tank 30 is led to the fine bubble generating means 43, and the hot water containing fine bubbles can be circulated while the downstream end of the circulation circuit 40 is connected to the lower connection port 34, making it possible to operate the scale adhesion prevention operation mode without disrupting the layer of high-temperature water at the top of the hot water storage tank 30, thereby preventing a drop in the temperature of the high-temperature water at the top of the hot water storage tank 30 and enhancing the scale adhesion prevention effect.

[0031] The control means 70 increases the circulation rate of the circulation pump 42 in the scale deposition prevention operation mode compared to the circulation rate of the circulation pump 42 in the boiling operation mode, thereby increasing the amount of fine bubbles generated in the scale deposition prevention operation mode. Furthermore, the control means 70 increases the circulation rate of the circulation pump 42 in the scale deposition prevention operation mode compared to the circulation rate of the circulation pump 42 in the initial boiling operation mode, thereby increasing the amount of fine bubbles generated in the scale deposition prevention operation mode. Furthermore, the control means 70 increases the circulation rate of the circulation pump 42 in the boiling operation mode compared to the circulation rate of the circulation pump 42 in the initial boiling operation mode. Therefore, by reducing the circulation rate in the initial boiling operation mode compared to the initial boiling operation mode, the temperature of the hot water returned to the hot water storage tank 30 in the initial boiling operation mode can be increased. Furthermore, the control means 70 increases the circulation rate of the circulation pump 42 in the scale deposition prevention operation mode compared to the circulation rate of the circulation pump 42 in the pipe freeze prevention operation mode. This makes it possible to increase the amount of fine bubbles generated in the scale deposition prevention operation mode.

[0032] Fig. 2 is a structural diagram of a storage type hot water heater according to another embodiment of the present invention. The same components as those in Fig. 1 are given the same reference numerals and their explanations will be omitted. In the embodiment shown in FIG. 2, the circulation circuit 40 has a fine bubble generation switching means 44 that switches whether or not the hot water is led to the fine bubble generating means 43. Specifically, a bypass flow path 39 is provided in the circulation circuit 40, and a microbubble generating means 43 is provided in the bypass flow path 39.

[0033] In the scale adhesion prevention operation mode, the control means 70 switches the fine bubble generation switching means 44 to guide the stored hot water to the fine bubble generating means 43, and in the boiling operation mode, the control means 70 switches the fine bubble generation switching means 44 to not guide the stored hot water to the fine bubble generating means 43. Therefore, pressure loss caused by the fine bubble generating means 43 in the boiling operation mode is eliminated, and power consumption can be reduced. Furthermore, in the scale adhesion prevention operation mode, the control means 70 can direct the stored hot water to the fine bubble generating means 43 by switching the fine bubble generation switching means 44, and in the boiling operation mode, the control means 70 can also direct the stored hot water intermittently to the fine bubble generating means 43 by switching the fine bubble generation switching means 44. In the boiling operation mode, by intermittently directing the stored hot water to the fine bubble generating means 43, the pressure loss caused by the fine bubble generating means 43 in the boiling operation mode can be reduced, and power consumption can be reduced. Furthermore, in the scale adhesion prevention operation mode, the control means 70 switches the fine bubble generation switching means 44 to guide the stored hot water to the fine bubble generating means 43, and in the initial boiling operation mode, the control means 70 switches the fine bubble generation switching means 44 to not guide the stored hot water to the fine bubble generating means 43. Therefore, the pressure loss caused by the fine bubble generating means 43 in the initial boiling operation mode can be reduced, and power consumption can be reduced. Furthermore, in the scale adhesion prevention operation mode, the control means 70 switches the fine bubble generation switching means 44 to guide the hot water to the fine bubble generating means 43, and in the pipe freezing prevention operation mode, the control means 70 switches the fine bubble generation switching means 44 to not guide the hot water to the fine bubble generating means 43. Therefore, the pressure loss caused by the fine bubble generating means 43 in the pipe freezing prevention operation mode can be reduced, and power consumption can be reduced. In this embodiment, the fine bubble generating means 43 is also disposed inside the hot water storage tank unit 1.

[0034] Fig. 3 is a structural diagram of a storage type hot water heater according to still another embodiment of the present invention. The same components as those in Fig. 1 are given the same reference numerals and their explanations will be omitted. Fig. 4 is a structural diagram of a storage type hot water heater according to still another embodiment of the present invention. The same components as those in Fig. 2 are given the same reference numerals and their explanations will be omitted. As shown in FIGS. 3 and 4, the microbubble generating means 43 may be disposed within the unit that constitutes the heating means 2. [Industrial Applicability]

[0035] According to the present invention, it is possible to suppress the deposition of scale inside the water-refrigerant heat exchanger and the hot water storage tank. [Explanation of symbols]

[0036] 1 Hot water tank unit 2. Heat pump unit (heating means) 4 Hot water tap 5. Water pipes 20 Heat pump circuit 21 Compressor 22 Water refrigerant heat exchanger 23 Pressure reducing device 24 Evaporator 25 Refrigerant piping 30 Hot water tank 31 Hot water outlet piping 32 Water supply piping 32a Branch pipe for hot water supply 33 Upper connection port 34 Lower connection port 35 Drainage piping 36 Drain plug 37 Pressure relief piping 38 Pressure relief valve 39 Bypass flow path 40 Circulation circuit 41 Flow path switching means 42 Circulation Pump 43 Microbubble generating means 44 Microbubble generation switching means 50 Hot water circuit 51 Hot water supply piping 52 Hot water mixing valve 60 Water supply circuit 70 Control Means

Claims

1. A hot water storage tank, a heating means for heating the hot water stored in the hot water storage tank; a circulation circuit that guides the hot water present in a lower portion of the hot water storage tank to the heating means and returns the hot water guided to the heating means to the hot water storage tank; a flow path switching means provided in the circulation circuit; a circulation pump provided in the circulation circuit; a control means for controlling a heating operation of the heating means and a switching operation of the flow path switching means; and The flow path switching means switches the downstream end of the circulation circuit between the upper connection port of the hot water storage tank and the lower connection port of the hot water storage tank. A storage type water heater, a microbubble generating means is provided in the circulation circuit; The control means a boiling operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the upper connection port of the hot water storage tank, and the heating operation is performed by the heating means; a scale adhesion suppression operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the lower connection port of the hot water storage tank, and the hot water in the hot water storage tank is circulated by the circulation pump; and At least in the scale adhesion suppression operation mode, the fine bubbles generated by the fine bubble generating means are guided to the hot water storage tank. A storage type water heater characterized by the above.

2. In the control means, Changing the circulation amount in the circulation pump; The circulation amount of the circulation pump in the scale adhesion prevention operation mode is set to be larger than the circulation amount of the circulation pump in the boiling operation mode.

2. The hot water storage type water heater according to claim 1.

3. The control means a boiling initial operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the lower connection port of the hot water storage tank, and the heating operation is performed by the heating means; Changing the circulation amount in the circulation pump; The circulation amount of the circulation pump in the scale adhesion suppression operation mode is set to be larger than the circulation amount of the circulation pump in the initial boiling operation mode.

2. The hot water storage type water heater according to claim 1.

4. The control means a pipe freeze prevention operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the lower connection port of the hot water storage tank, and performs a pipe freeze prevention operation; Changing the circulation amount in the circulation pump; The circulation amount of the circulation pump in the scale adhesion prevention operation mode is set to be larger than the circulation amount of the circulation pump in the pipe freeze prevention operation mode.

2. The hot water storage type water heater according to claim 1.

5. The circulation circuit has a micro-bubble generation switching means for switching whether or not the stored hot water is led to the micro-bubble generating means, The control means In the scale adhesion suppression operation mode, the hot water is introduced into the fine bubble generating means by switching the fine bubble generating switching means, In the boiling operation mode, the hot water is not introduced to the fine bubble generating means by switching the fine bubble generating switching means.

5. The hot water storage type water heater according to claim 1, wherein the hot water storage type water heater comprises:

6. The circulation circuit has a micro-bubble generation switching means for switching whether or not the stored hot water is led to the micro-bubble generating means, The control means In the scale adhesion suppression operation mode, the hot water is introduced into the fine bubble generating means by switching the fine bubble generating switching means, In the boiling operation mode, the stored hot water is intermittently introduced to the fine bubble generating means by switching the fine bubble generating switching means.

5. The hot water storage type water heater according to claim 1, wherein the hot water storage type water heater comprises:

7. The circulation circuit has a micro-bubble generation switching means for switching whether or not the stored hot water is led to the micro-bubble generating means, The control means a boiling initial operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the lower connection port of the hot water storage tank, and the heating operation is performed by the heating means; In the scale adhesion suppression operation mode, the hot water is introduced into the fine bubble generating means by switching the fine bubble generating switching means, In the initial boiling operation mode, the hot water is not introduced to the fine bubble generating means by switching the fine bubble generating switching means.

5. The hot water storage type water heater according to claim 1, claim 2, or claim 4.

8. The circulation circuit has a micro-bubble generation switching means for switching whether or not the stored hot water is led to the micro-bubble generating means, The control means a pipe freeze prevention operation mode in which the flow path switching means switches the downstream end of the circulation circuit to the lower connection port of the hot water storage tank, and performs a pipe freeze prevention operation; In the scale adhesion suppression operation mode, the hot water is introduced into the fine bubble generating means by switching the fine bubble generating switching means, In the pipe freeze prevention operation mode, the hot water is not introduced to the fine bubble generating means by switching the fine bubble generating switching means. The hot water storage type water heater according to any one of claims 1 to 3.

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