Water heater

Abstract

To provide a water heater that can avoid quality deterioration of hot water intended for drinking while adopting resin components derived from a recycled material.SOLUTION: A water heater comprises a heat pump unit for generating hot water by exchanging heat between low-temperature water and a high-temperature refrigerant, and a hot water storage unit for storing the hot water supplied from the heat pump unit. A resin derived from a virgin material is used for pipe joints, valves, and pumps arranged in drinking water flow passages in contact with drinking water. A resin derived from a recycled material is used for pipe joints, valves, and pumps arranged in non-drinking water flow passages not in contact with drinking water.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water heater that uses both resin parts made from virgin materials and resin parts made from recycled materials. [Background technology]

[0002] The pipe joint of Patent Document 1 is known as a resin part used in a water heater. For example, claim 11 of the document states "a water heater equipped with a pipe joint," and paragraph 0032 states "The pipe joint 1 is molded from a resin such as PPS." In other words, Patent Document 1 discloses a water heater equipped with a pipe joint molded from a resin such as PPS (polyphenylene sulfide).

[0003] Patent Document 1 does not mention the origin of the resin used in the pipe fittings, but in equipment that handles drinking water, food, etc., the use of resin parts made from recycled materials, which tend to have a stronger odor and a higher impurity content than virgin materials, has usually been avoided in order to avoid deterioration of the quality of drinking water, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6673477 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, in order to realize a sustainable society, there has been a growing demand to replace plastic parts that were previously made from virgin materials with those made from recycled materials.

[0006] Therefore, an object of the present invention is to provide a water heater that uses resin parts made from recycled materials while avoiding deterioration in the quality of hot water intended for drinking. [Means for solving the problem]

[0007] In order to solve the above problems, the water heater of the present invention is a water heater equipped with a heat pump unit that generates hot water by heat exchange between low-temperature water and high-temperature refrigerant, and a hot water storage unit that stores the hot water supplied from the heat pump unit, in which resins derived from virgin materials are used for pipe fittings, valves, or pumps placed in a drinking water flow path that comes into contact with drinking water, and resins derived from recycled materials are used for pipe fittings, valves, or pumps placed in a non-potable water flow path that does not come into contact with drinking water. Effect of the Invention

[0008] According to the water heater of the present invention, it is possible to avoid deterioration in the quality of hot water intended for drinking while using resin parts made from recycled materials. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of a water heater according to a first embodiment. [Diagram 2] FIG. 6 is a schematic configuration diagram of a water heater according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a water heater according to the present invention will be described with reference to the drawings. EXAMPLES

[0011] First, a water heater 1 according to a first embodiment, in which purified water is supplied from a water supply, will be described with reference to Fig. 1. In the following, water intended for drinking and supplied to kitchens, washrooms, etc. (water that meets the quality standards set by the Water Supply Act) will be referred to as potable water, and water not intended for drinking and supplied to bathtubs, etc. in bathrooms will be referred to as non-potable water.

[0012] Fig. 1 is a schematic configuration diagram of a water heater 1 of Example 1. The water heater 1 of this embodiment is a water heater that stores drinking water in a tank, and includes a heat pump unit 10 and a hot water storage unit 20. Details of each unit will be described below in order.

[0013] <Heat pump unit 10> The heat pump unit 10 is a unit that converts low-temperature water (drinking water) supplied from the hot water storage unit 20 into hot water of about 90°C and returns it to the hot water storage unit 20. As shown in Fig. 1, the heat pump unit 10 includes a circulation pump 11, a water-refrigerant heat exchanger 12, a control board 13, and a compressor (not shown).

[0014] The circulation pump 11 draws low-temperature water (drinking water) from the hot water storage unit 20 and supplies it to the water-refrigerant heat exchanger 12. The water-refrigerant heat exchanger 12 produces hot water by heat exchange between a high-temperature refrigerant supplied from a compressor (not shown) and the low-temperature water (drinking water) supplied from the circulation pump 11. The control board 13 controls the circulation pump 11, the compressor, etc. to produce a desired amount of hot water according to commands from a control board 21 of the hot water storage unit 20, which will be described later.

[0015] <Hot water storage unit 20> The hot water storage unit 20 is a unit that supplies low-temperature water (drinking water) to the heat pump unit 10, stores hot water (drinking water) recovered from the heat pump unit 10, and supplies hot water to the kitchen, bathroom, etc. As shown in Fig. 1, the hot water storage unit 20 includes a control board 21, a water supply solenoid valve 22, a tank 23, a three-way valve 24, a hot water supply mixing valve 25, a bath mixing valve 26, a bath solenoid valve 27, a bath circulation pump 28, a circulation adjustment valve 29, and piping that connects them. Note that check valves provided at various points in the hot water storage unit 20 separate non-potable water so that it does not mix with the drinking water. Below, the function of each part of the hot water storage unit 20 will be explained for each control state of the water heater 1.

[0016] <<Control of water injection into Tank 23>> When it is desired to pour purified water from the water supply into the tank 23, the control board 21 opens the water supply solenoid valve 22 to form a flow path from the water supply to the tank 23. This allows low-temperature purified water (drinking water) to be supplied to the bottom of the tank 23 via a strainer, a check valve, the water supply solenoid valve 22, a pressure reducing valve, etc.

[0017] <<Control of heating of drinking water in tank 23>> When it is desired to heat the low-temperature water (drinking water) in the tank 23 by the heat pump unit 10, the control board 21 first switches the three-way valve 24 to form a flow path from the bottom of the tank 23 toward the circulation pump 11. Thereafter, the control board 21 drives the circulation pump 11 via the control board 13 of the heat pump unit 10 to send the low-temperature water (drinking water) in the bottom of the tank 23 to the water-refrigerant heat exchanger 12, and drives the compressor to send the high-temperature refrigerant to the water-refrigerant heat exchanger 12. As a result, in the water-refrigerant heat exchanger 12 of the heat pump unit 10, heat exchange is performed between the low-temperature water (drinking water) and the high-temperature refrigerant, and hot water of about 90° C. is generated. The hot drinking water is collected in the upper part of the tank 23.

[0018] <<Freezing prevention control for the pipes connecting both units>> The pipes connecting the heat pump unit 10 and the hot water storage unit 20 are exposed to the outside air, so there is a risk that the water in the pipes will freeze in winter. Therefore, the control board 21 executes anti-freezing control of the pipes connecting both units at appropriate times. Specifically, the control board 21 first switches the three-way valve 24 so as to form a circulation flow path connecting the outflow side pipe of the water-refrigerant heat exchanger 12 and the inflow side pipe of the circulation pump 11. After that, the control board 21 drives the circulation pump 11 via the control board 13 of the heat pump unit 10 to send low-temperature water (drinking water) in the circulation flow path to the water-refrigerant heat exchanger 12, and drives the compressor to send high-temperature refrigerant to the water-refrigerant heat exchanger 12. As a result, heat exchange between the low-temperature water (drinking water) and the high-temperature refrigerant is performed in the water-refrigerant heat exchanger 12, and hot water at about 90° C. circulates through the circulation flow path, so that the pipes connecting both units can be prevented from freezing.

[0019] <<Hot water supply control to the kitchen>> When a user operates the kitchen remote control 30 to instruct hot water to be supplied to the kitchen, the control board 21, which receives the instruction, opens the water supply solenoid valve 22 to form a flow path from the water supply to the hot water supply mixing valve 25. This flow path supplies low-temperature water (drinking water) to one inlet end of the hot water supply mixing valve 25. When low-temperature water (drinking water) is supplied to the lower part of the tank 23 by opening the water supply solenoid valve 22, high-temperature drinking water flows out from the upper part of the tank 23 and is supplied to the other inlet end of the hot water supply mixing valve 25. Therefore, the control board 21 can supply hot water at a temperature specified by the kitchen remote control 30 to the kitchen by appropriately controlling the mixing ratio in the hot water supply mixing valve 25 according to the outputs of a hot water supply flow rate sensor and a hot water supply temperature sensor (not shown).

[0020] <<Bathtub 2 filling control>> When a user operates the bath remote control 40 to instruct the bathtub 2 to be filled with water, the control board 21, which receives the instruction, opens the water supply solenoid valve 22 to form a flow path from the water supply to the bath mixing valve 26. This flow path supplies low-temperature water (drinking water) to one inlet end of the bath mixing valve 26. When low-temperature water (drinking water) is supplied to the bottom of the tank 23 by opening the water supply solenoid valve 22, high-temperature drinking water flows out from the top of the tank 23 and is supplied to the other inlet end of the bath mixing valve 26. Therefore, the control board 21 appropriately controls the mixing ratio in the bath mixing valve 26 according to the output of the bath flow rate sensor and the bath return temperature sensor (not shown), and further controls the opening and closing of the bath solenoid valve 27 according to the output of the water level sensor (not shown), thereby supplying hot water to the bathtub 2 at the temperature and amount specified by the bath remote control 40.

[0021] <<Bathtub 2 reheating control>> When a user operates the bath remote control 40 to instruct the reheating of hot water in the bathtub 2, the control board 21 that receives the instruction controls the flow ratio at the circulation adjustment valve 29 downstream of the bath circulation pump 28 while the water supply solenoid valve 22 is closed, and forms a first flow path toward the reheating heat exchanger 23a arranged in the tank 23 and a second flow path returning to the bathtub 2. The control board 21 then drives the bath circulation pump 28 to send the cold hot water in the bathtub 2 to the reheating heat exchanger 23a via the first flow path. This causes heat exchange between the cold hot water flowing in the reheating heat exchanger 23a and the hot water in the upper part of the tank 23, and the cold hot water is reheated to about 90°C. The reheated hot water is mixed with the cold hot water that has passed through the second flow path, and returns to the bathtub 2 at the appropriate temperature instructed by the user. In this way, the hot water in the bathtub 2 can be reheated.

[0022] <Layout of parts made from recycled materials> Next, the arrangement of resin parts and the like made from recycled materials in the hot water heater 1 of this embodiment will be described. Prior to the description, the terms "drinking water flow path" and "non-potable water flow path" used in this embodiment will be defined. That is, in this embodiment, a flow path that comes into contact with drinking water, as shown by dotted lines in Fig. 1, is defined as a drinking water flow path, and a flow path that does not come into contact with drinking water, as shown by dashed lines in Fig. 1, is defined as a non-potable water flow path. Therefore, even if a flow path through which non-potable water flows, if it comes into contact with drinking water (for example, reheating heat exchanger 23a), it is classified as a drinking water flow path in this embodiment.

[0023] As described above, resin parts made from recycled materials tend to have a stronger odor and a higher content of impurities (phenols, organic matter, etc.) than resin parts made from virgin materials. Therefore, since it is believed that placing resin parts made from recycled materials in the drinking water flow path will cause deterioration in the quality of the drinking water, it is desirable to place resin parts made from virgin materials in the drinking water flow path to suppress deterioration in the quality of the drinking water (deterioration of taste, odor, color, turbidity, etc.). On the other hand, even if some odor is added to the hot water supplied to the bathtub 2 or some impurities are mixed in, it is not a problem under the Water Supply Act, and it is also believed that there is no actual harm to the user unless the hot water in the bathtub 2 is drunk, so in order to promote the use of recycled materials, it is desirable to place parts made from recycled materials in the non-potable water flow path.

[0024] Therefore, in the hot water heater 1 of this embodiment, a resin part made of virgin material is arranged in the drinking water flow path, and a resin part made of recycled material is arranged in the non-potable water flow path. Note that the resin part made of recycled material in this embodiment is not limited to a resin part made of only recycled material, but is a concept including a resin part made of a mixture of recycled material and virgin material. Also, the resin part made of virgin material in this embodiment is not limited to a resin part made of only virgin material, but is a concept including a resin part made of a mixture of recycled material and virgin material, in which the ratio of recycled material used is significantly lower than that of the resin part made of recycled material used in combination.

[0025] For example, approximately T-shaped plastic pipe fittings are used in each part of the water heater 1 to connect three pipes, but in this embodiment, a pipe fitting J (shown as a white convex in Figure 1) made from virgin material is used for the drinking water flow path, and a pipe fitting J' (shown as a black convex in Figure 1) made from recycled material is used for the non-potable water flow path.

[0026] For drinking water flow paths, it is preferable to use pipe fittings J made from virgin materials for all or almost all of the pipe fittings, but pipe fittings J' made from recycled materials may be used if, for example, the residual odor can be suppressed below the human perception threshold. Also, for non-potable water flow paths, from the viewpoint of increasing the usage rate of recycled materials, it is preferable to use pipe fittings J' made from recycled materials for all or almost all of the pipe fittings. That is, pipe fittings J' may be used until the residual odor exceeds the human perception threshold, or may be suppressed below the perception threshold because non-potable water is used for bath water, etc.

[0027] Here, the resin parts of the water heater 1 are made of PPS (polyphenylene sulfide), a crystalline resin with excellent water resistance, heat resistance, and chemical resistance, as well as PPE (polyphenylene ether) and SPS (syndiotactic polystyrene), which are amorphous resins with similar properties. In this case, the residual odor can be a sulfur odor. The perception threshold of the sulfur odor can be considered to be 0.5 ppm.

[0028] When these resins are used to mold pipe fittings, glass fiber reinforcement is usually mixed into the resin to increase mechanical strength. As a result, the surface of pipe fittings made from recycled materials tends to be rough because the glass fiber reinforcement that was crushed during the resin recycling process is exposed. Therefore, pipe fittings made from recycled materials have the disadvantage of being inferior in airtightness compared to pipe fittings made from virgin materials, which have a smooth surface. The surface roughness of pipe fittings is generally evaluated using the ten-point average roughness (Rz), and it is said that if Rz exceeds 6.3, the risk of water leakage from the pipe fitting increases.

[0029] Considering this, in the hot water heater 1 of this embodiment, pipe fittings made of virgin materials with smooth surfaces and high airtightness are arranged in the drinking water flow path that receives a relatively high water pressure, and pipe fittings made of recycled materials with relatively rough surfaces and low airtightness are arranged in the non-drinking water flow path that receives a relatively low water pressure. With this arrangement, even pipe fittings made of recycled materials with inferior airtightness can satisfy the airtightness required for the non-drinking water flow path, so water leakage from pipe fittings made of recycled materials can be avoided.

[0030] The use of resin made from recycled materials is not limited to pipe joints, but may also be used for valves, pumps, piping, etc.

[0031] For example, when using resin made from recycled materials for valves and pumps, resin parts made from virgin materials can be used for the valves and pumps placed in the drinking water flow path (e.g., circulation pump 11, water supply solenoid valve 22, three-way valve 24, hot water mixing valve 25, bath mixing valve 26, bath solenoid valve 27, etc.), and resin parts made from recycled materials can be used for the valves and pumps placed in the non-potable water flow path (e.g., bath circulation pump 28, circulation adjustment valve 29).

[0032] Similarly, when using resin derived from recycled materials for piping, resin parts derived from virgin materials can be used for the piping arranged in the drinking water flow path, and resin parts derived from recycled materials can be used for the piping arranged in the non-potable water flow path. In the case of piping that contacts both drinking water and non-potable water, such as the reheating heat exchanger 23a, the entire piping may be molded from resin derived from recycled materials, or two layers of resin derived from virgin materials and resin derived from recycled materials may be molded, with the virgin resin surface in contact with the drinking water and the recycled resin surface in contact with the non-potable water.

[0033] As described above, according to the water heater of this embodiment, by placing resin parts made from recycled materials in the non-potable water flow path, the use of recycled materials is promoted, while by placing resin parts made from virgin materials in the potable water flow path, deterioration in the quality of hot water intended for drinking can be avoided. EXAMPLES

[0034] Next, a water heater 1A according to a second embodiment, in which purified water is supplied from a well, will be described with reference to Fig. 2. Note that a duplicated description of points common to the first embodiment will be omitted.

[0035] 2 is a schematic diagram of a water heater 1A of Example 2. The water heater 1A of this example is a water heater that stores non-potable water in a tank, and includes a heat pump unit 10 and a hot water storage unit 20A. Each unit will be described in detail below.

[0036] <Heat pump unit 10> In the first embodiment, potable water is stored in the tank 23 and is supplied from the tank 23 to the heat pump unit 10, so the flow path connecting the heat pump unit 10 and the hot water storage unit 20 is classified as a potable water flow path. In contrast, in the present embodiment, non-potable water is stored in the tank 23 and is supplied from the tank 23 to the heat pump unit 10, so the flow path connecting the heat pump unit 10 and the hot water storage unit 20A is classified as a non-potable water flow path. Other than this, the heat pump units 10 in both embodiments are equivalent, so duplicated explanations regarding the configuration and functions of the heat pump unit 10 will be omitted.

[0037] <Hot water storage unit 20A> The hot water storage unit 20A is a unit that supplies low-temperature water (non-potable water) to the heat pump unit 10, stores hot water (non-potable water) recovered from the heat pump unit 10, and supplies hot water to the kitchen, bathroom, etc. This hot water storage unit 20A has various components as shown in Fig. 2, but since the functions of each part are well known, detailed explanations will be omitted except for elements that are particularly necessary.

[0038] As shown in Figure 2, the hot water storage unit 20A of this embodiment heats drinking water to a desired temperature by heat exchange in a heat exchanger 2a between low-temperature water (drinking water) supplied from a well and hot water (non-potable water) of about 90°C taken out from the top of the tank 23, and when supplying hot water to the kitchen or filling the bathtub 2, the hot water generated in the heat exchanger 2a is supplied to the kitchen, bathtub 2, etc.

[0039] 2, in which the heat exchanger 2a is disposed immediately after the water supply end of the hot water storage unit 20A, the drinking water flow path shown by the dotted line is shorter and the non-potable water flow path shown by the dashed line is longer than in the hot water heater 1 of the first embodiment. This expands the area in which pipe fittings J' (black convex in the figure), valves, pumps, piping, etc., made of resin derived from recycled materials can be disposed, and in the case of using a resin-molded tank 23, it is also possible to mold the tank 23 from resin derived from recycled materials. Therefore, the hot water heater 1A of this embodiment can promote the use of recycled materials more than the hot water heater 1 of the first embodiment. [Explanation of symbols]

[0040] 1. Water heater 10 Heat pump unit 11 Circulation pump 12 Water refrigerant heat exchanger 13 Control Board 20 Hot water storage unit 21 Control board 22 Water supply solenoid valve 23 Tank 23a Reheating heat exchanger 24 Three-way valve 25 Hot water mixing valve 26 Bath Mixing Valve 27 Bath solenoid valve 28 Bath Circulation Pump 29 Circulation Regulating Valve 2a heat exchanger 30 Kitchen remote control 40 Bath remote control 2 Bathtub J Pipe fittings made from virgin materials J' Pipe fittings made from recycled materials

Claims

1. a heat pump unit that generates hot water by heat exchange between low-temperature water and a high-temperature refrigerant; a hot water storage unit that stores the hot water supplied from the heat pump unit; A water heater comprising: The pipe joints, valves, or pumps to be placed in non-potable water flow paths that do not come into contact with potable water use resins made from recycled materials. At least a resin derived from virgin materials is used for pipe joints, valves, or pumps arranged in a drinking water flow path that comes into contact with drinking water, A water heater characterized in that the residual odor of the non-potable water supplied from the hot water storage unit is stronger than the residual odor of the potable water supplied from the hot water storage unit.

2. A heat pump unit that generates hot water by heat exchange between low-temperature water and a high-temperature refrigerant; a hot water storage unit that stores the hot water supplied from the heat pump unit; A water heater comprising: The pipe joints, valves, or pumps to be placed in non-potable water flow paths that do not come into contact with potable water use resins made from recycled materials. At least a resin derived from virgin materials is used for pipe joints, valves, or pumps arranged in a drinking water flow path that comes into contact with drinking water, A water heater characterized in that a residual impurity concentration of non-potable water supplied from the hot water storage unit is higher than a residual impurity concentration of potable water supplied from the hot water storage unit.

3. In the water heater according to claim 1 or 2, A water heater characterized in that a resin derived from recycled materials is used for piping arranged in the non-potable water flow path.

4. In the water heater according to claim 1 or 2, The water heater, wherein the resin is polyphenylene sulfide (PPS), polyphenylene ether (PPE), or syndiotactic polystyrene (SPS).

5. In claim 4, A hot water heater characterized in that the sulfur odor of the non-potable water supplied from the hot water storage unit is equal to or greater than the human perception threshold.

6. In claim 4, The sulfur odor of the non-potable water supplied from the hot water storage unit is below the human perception threshold, A water heater characterized in that the total amount of resin made from recycled materials used in the pipe fittings, valves, or pumps placed in the non-potable water flow path is greater than the total amount of resin made from recycled materials used in the pipe fittings, valves, or pumps placed in the potable water flow path that comes into contact with potable water.

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