Patent Application
20240044515
The present disclosure relates to a storage water heater.
Some storage water heater executes a heat-up operation by drawing hot water in a hot-water storage tank from the bottom part of the hot-water storage tank, heating the hot water to a high temperature through a heat-pump heating means, and then returning the high-temperature hot water to the top part of the hot-water storage tank (e.g., Patent Literature 1).
In such a storage water heater, the heat-up operation causes high-temperature hot water to be stored gradually from the top part of the hot-water storage tank. In the hot-water storage tank, low-temperature hot water and high-temperature hot water are stored in layers such that the low-temperature hot water with its large density accumulates in the lower part and the high-temperature hot water with its small density accumulates in the upper part. The temperature of hot water is thus lower in the lower part of the hot-water storage tank than in the upper part. In particular, when tap water is supplied to the hot-water storage tank upon supply of hot water to an external location, temperature is caused to drop in areas such as the lower part of the hot-water storage tank and the interior of a pipe located in a passage connected to the lower part of the hot-water storage tank. Such areas with decreased temperature provide an environment conducive to microbial growth. This makes it difficult to ensure long-term maintenance of hygiene.
The present disclosure is directed to addressing the above-mentioned problem. Accordingly, the present disclosure provides a storage water heater that prevents an environment conducive to microbial growth from being created in the lower part of the hot-water storage tank and in a passage connected to the lower part of the hot-water storage tank and that consequently ensures long-term maintenance of hygiene.
A storage water heater according to an embodiment of the present disclosure includes a heating device, a hot-water storage tank, a first passage, and a controller. The hot-water storage tank stores hot water. The first passage is connected to a lower part of the hot-water storage tank. The controller is configured to selectively switch between a heat-up operation and a recirculation operation. In the heat-up operation, hot water flowing out from the hot-water storage tank is delivered to the heating device via the first passage and then hot water heated by the heating device is delivered to an upper part of the hot-water storage tank. In the recirculation operation, hot water flowing out from the upper part of the hot-water storage tank is delivered to the lower part of the hot-water storage tank via the first passage.
With the storage water heater according to an embodiment of the present disclosure, hot water flowing out from the upper part of the hot-water storage tank is delivered to the lower part of the hot-water storage tank. This makes it possible to inhibit microbial growth and to improve maintenance of hygiene in the lower part of the hot-water storage tank and in a passage connected to the lower part of the hot-water storage tank.
Embodiments of the present disclosure are described below with reference to the drawings. In the drawings used herein, the same elements are provided with the same reference signs. The present disclosure is not limited to the embodiments below but may be variously modified without departing from the gist of the present disclosure.
<Configuration of Storage Water Heater>
The storage water heater 1 stores hot water heated by the heat pump unit 200, which is a heating device, into a hot-water storage tank 101 of the hot-water storage unit 10.
The heat pump unit 200 includes, for example, the following components (not illustrated): a compressor, a water-to-refrigerant heat exchanger, an expansion valve, and an air heat exchanger. These components are connected in a loop to form a refrigeration cycle circuit in which refrigerant is to be circulated.
Although the following description is directed to an exemplary case where the heating device is the heat pump unit 200, the heating device may be a combustion heater that heats water through combustion of a fuel such as gas and oil.
The hot-water storage tank 101 serves to store hot water. The hot-water storage tank 101 includes a first inlet-outlet port 101a, and a second inlet-outlet port 101b. In the vertical direction corresponding to the up-and-down direction illustrated in
The hot-water storage tank 101 further includes a water supply port 101c located in the lower part of the hot-water storage tank 101 and through which tap water is supplied. Although the water supply port 101c is located in the lower part of the hot-water storage tank 101 in the example illustrated in
A passage 11 connects the upper and lower parts of the hot-water storage tank 101. The passage 11 includes the following passages in a location external to the hot-water storage tank 101: a first passage 111, a second passage 112, a third passage 113, and a fourth passage 114. Each of the first to fourth passages 111 to 114 is in the form of, for example, a pipe that delivers hot water. A circulation pump 102, a four-way valve 103, and the heat pump unit 200 are disposed in the passage 11.
The storage water heater 1 selectively switches between and executes a heat-up operation and a recirculation operation. A heat-up operation is executed by, through activation of the circulation pump 102, causing hot water to flow out from the second inlet-outlet port 101b located in the lower part of the hot-water storage tank 101 into the passage 11, supplying the hot water, which has flowed out, toward an inlet portion of the heat pump unit 200 disposed in the passage 11, and then delivering, to the first inlet-outlet port 101a located in the upper part of the hot-water storage tank 101, hot water heated by the heat pump unit 200 and flowing out from an outlet portion of the heat pump unit 200.
A recirculation operation is executed by, through activation of the circulation pump 102, routing hot water flowing out from the first inlet-outlet port 101a, which is located in the upper part of the hot-water storage tank 101, through the passage 11 for delivery to the second inlet-outlet port 101b, which is located in the lower part of the hot-water storage tank 101. The controller 300 selectively switches between the heat-up operation and the recirculation operation mentioned above, and controls how a switching unit described later, the circulation pump 102, and the heat pump unit 200 operate during each of these operations. Details of the heat-up operation and the recirculation operation will be given later.
The heat-up operation and the recirculation operation differ from each other in the direction of hot water delivery but cause hot water to be routed through the same passage 11. It is to be noted, however, that in an example described later, the heat-up operation and the recirculation operation differ from each other in the order in which hot water flows through the four passages (the first to fourth passages 111 to 114) included in the passage 11. The four-way valve 103 is disposed in the passage 11. The four-way valve 103 serves as a switching unit that, by switching which other passage each one of the four passages (the first to fourth passages 111 to 114) communicates with, switches in what order hot water flows through the four passages. The circulation pump 102 is activated in each of the heat-up operation and the recirculation operation to pass hot water through the passage 11. In an alternative arrangement, another circulation device may be provided such that the circulation pump 102 is activated during only one of the heat-up operation and the recirculation operation, and the other circulation device is activated during the other operation.
The four-way valve 103 includes four water inlet-outlet ports through which hot water flows in and out. The four water inlet-outlet ports include a first water inlet-outlet port 3a, a second water inlet-outlet port 3b, a third water inlet-outlet port 3c, and a fourth water inlet-outlet port 3d. The first passage 111 connects the first water inlet-outlet port 3a of the four-way valve 103 with the second inlet-outlet port 101b located in the lower part of the hot-water storage tank 101. The second passage 112 connects the second water inlet-outlet port 3b of the four-way valve 103 with the hot-water inlet portion of the heat pump unit 200. The third passage 113 connects the third water inlet-outlet port 3c of the four-way valve 103 with the hot-water outlet portion of the heat pump unit 200. The fourth passage 114 connects the fourth water inlet-outlet port 3d of the four-way valve 103 with the first inlet-outlet port 101a located in the upper part of the hot-water storage tank 101. The fourth passage 114 includes a branch part 114a located at a point in the fourth passage 114. The fourth passage 114 is thus connected to not only the first inlet-outlet port 101a located in the upper part of the hot-water storage tank 101, but also to an inlet 1b of a mixing valve 121 described later and an inlet 2b of a mixing valve 122 described later.
Although the circulation pump 102 is illustrated in
In the hot-water storage unit 10, tap water is supplied from the water supply end 120 into the hot-water storage tank 101 through the water supply port 101c located in the lower part of the hot-water storage tank 101. The water supply end 120 is connected to the water supply port 101c via a fifth passage 115 and via a branch part 115a, which is located at a point in the fifth passage 115. The fifth passage 115 is in the form of, for example, a pipe that delivers water.
To the water supply end 120, the mixing valve 121 and the mixing valve 122 are connected. The mixing valve 121 includes inlets 1a and 1b, and an outlet 1c. The mixing valve 122 includes inlets 2a and 2b, and an outlet 2c.
The water supply end 120 is connected via the branch part 115a, which is located at a point in the fifth passage 115, to the inlet 1a of the mixing valve 121 and to the inlet 2a of the mixing valve 122. The inlet 1b of the mixing valve 121, and the inlet 2b of the mixing valve 122 are each connected via the fourth passage 114 to the first inlet-outlet port 101a of the hot-water storage tank 101 and to the fourth water inlet-outlet port 3d of the four-way valve 103.
The outlet 1c of the mixing valve 121 is connected via a sixth passage 116 to the hot-water supply end 124. A thermistor 131 is disposed at a point in the sixth passage 116. The thermistor 131 serves as a warm-water-temperature detection unit that detects the temperature of warm water that is supplied to the hot-water supply end 124.
The outlet 2c of the mixing valve 122 is connected via a seventh passage 117 to the bathtub 400. A thermistor 132 is disposed at a point in the seventh passage 117. The thermistor 132 serves as a warm-water-temperature detection unit that detects the temperature of warm water that is supplied to the bathtub 400. The measurement results obtained by the thermistor 131 and the thermistor 132 are sent to the controller 300. The sixth passage 116 and the seventh passage 117 are each in the form of, for example, a pipe that delivers warm water.
<Heat-Up Operation>
A heat-up operation to be performed by the storage water heater 1 according to Embodiment 1 is described below with reference to
An exemplary heat-up operation is described below in which hot water drawn from the lower part of the hot-water storage tank 101 is heated by the heat pump unit 200 disposed in the passage 11 before the hot water is delivered to the upper part of the hot-water storage tank 101. In
The controller 300 controls the four-way valve 103 such that, in executing the heat-up operation, the four-way valve 103 causes the first water inlet-outlet port 3a to communicate with the second water inlet-outlet port 3b, and causes the third water inlet-outlet port 3c to communicate with the fourth water inlet-outlet port 3d. At this time, the four-way valve 103 is switched to a heat-up operation state in which the first passage 111 and the second passage 112 communicate with each other and in which the third passage 113 and the fourth passage 114 communicate with each other.
With the four-way valve 103 controlled in this manner, the controller 300 activates the circulation pump 102. Consequently, in the passage 11, hot water is sequentially introduced from the second inlet-outlet port 101b, which is located in the lower part of the hot-water storage tank 101, to the first passage 111, the first water inlet-outlet port 3a of the four-way valve 103, the second water inlet-outlet port 3b, the second passage 112, the circulation pump 102, the heat pump unit 200, the third passage 113, the third water inlet-outlet port 3c of the four-way valve 103, the fourth water inlet-outlet port 3d, the fourth passage 114, and then to the first inlet-outlet port 101a, which is located in the upper part of the hot-water storage tank 101.
The controller 300 controls the heat pump unit 200 such that the heat pump unit 200 heats hot water flowing into the inlet portion of the heat pump unit 200, and causes the heated hot water to flow out toward the outlet portion of the heat pump unit 200.
In this manner, a heat-up operation is executed, in which hot water drawn from the lower part of the hot-water storage tank 101 is heated by the heat pump unit 200 serving as a heating device and then the heated hot water is delivered to the upper part of the hot-water storage tank 101. For example, the hot water to be delivered to the hot-water storage tank 101 is heated in the heat pump unit 200 to a temperature of 45 degrees C. or above.
Through the heat-up operation mentioned above, in the up-and-down direction of the hot-water storage tank 101 illustrated in
<Recirculation Operation>
A recirculation operation to be performed by the storage water heater 1 according to Embodiment 1 is described below with reference to
When hot water is to be used at the bathtub 400 or the hot-water supply end 124 after the heat-up operation mentioned above, hot water flowing out from the first inlet-outlet port 101a in the upper part of the hot-water storage tank 101 passes through the fourth passage 114, where the hot water is mixed at the mixing valve 121 or the mixing valve 122 with tap water supplied from the water supply end 120. The hot water is thus adjusted in temperature, and supplied to the hot-water supply end 124 or the bathtub 400 as warm water. As warm water is supplied to an external location in this manner, tap water is supplied via the fifth passage 115 from the water supply end 120 into the hot-water storage tank 101 through the water supply port 101c. In
Tap water is usually colder and denser than the hot water in the hot-water storage tank 101, and thus accumulates in the lower part of the hot-water storage tank 101. This causes the temperature of hot water to decrease in the lower part of the hot-water storage tank 101. Typically, microorganisms such as bacteria and fungi thrive at temperatures between 20 and 40 degrees C. Accordingly, when hot water is maintained at a temperature between 20 to 40 degrees C., a build-up of microbial cells or microorganisms deposits as a biofilm attached at locations such as on the bottom and wall surface of the hot-water storage tank 101 and on the interior of a passage connected to the lower part of the hot-water storage tank 101. Attachment of microorganisms, biofilms, or other contaminants makes it difficult to keep hot water hygienic. The storage water heater 1 according to Embodiment 1 executes the recirculation operation to maintain hygiene by inhibiting microbial growth in the lower part of the hot-water storage tank 101 and in the passage 11, which is connected from the lower part of the hot-water storage tank 101 to the upper part of the hot-water storage tank 101. In particular, the hygiene in the pipe of the first passage 111 connected to the lower part of the hot-water storage tank 101 is improved.
In
The controller 300 controls the four-way valve 103 such that, in executing the recirculation operation, the four-way valve 103 causes the second water inlet-outlet port 3b to communicate with the fourth water inlet-outlet port 3d, and causes the first water inlet-outlet port 3a to communicate with the third water inlet-outlet port 3c. At this time, the four-way valve 103 is switched to a recirculation operation state in which the fourth passage 114 and the second passage 112 communicate with each other and in which the third passage 113 and the first passage 111 communicate with each other.
With the four-way valve 103 controlled in this manner, the controller 300 activates the circulation pump 102. Consequently, in the passage 11, hot water is sequentially introduced from the first inlet-outlet port 101a, which is located in the upper part of the hot-water storage tank 101, to the fourth passage 114, the fourth water inlet-outlet port 3d of the four-way valve 103, the second water inlet-outlet port 3b, the second passage 112, the circulation pump 102, the heat pump unit 200, the third passage 113, the third water inlet-outlet port 3c of the four-way valve 103, the first water inlet-outlet port 3a, the first passage 111, and then to the second inlet-outlet port 101b, which is located in the lower part of the hot-water storage tank 101.
In this manner, hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101.
At this time, the controller 300 stops heating performed by the heat pump unit 200 disposed in the passage 11, and allows only passage of water through the heat pump unit 200. In this manner, a recirculation operation is executed in which high-temperature hot water drawn from the upper part of the hot-water storage tank 101 is delivered to and circulated in the lower part of the hot-water storage tank 101. Executing such a recirculation operation causes the temperature in the lower part of the hot-water storage tank 101 to rise to a temperature that limits microbial growth. The recirculation operation also makes it possible to sterilize under high temperature, or disinfect under running water, the interiors of the following components disposed in the passage 11 connected from the lower part of the hot-water storage tank 101 to the upper part of the hot-water storage tank 101: the first passage 111, the second passage 112, the third passage 113, the fourth passage 114, the four-way valve 103, the circulation pump 102, and the heat pump unit 200.
At this time, high-temperature hot water drawn from the upper part of the hot-water storage tank 101 is used. This makes it possible to efficiently maintain, in an energy-saving manner without use of a heating device, the hygiene in the lower part of the hot-water storage tank 101 and in the passage 11, which is connected from the lower part of the hot-water storage tank 101 to the upper part of the hot-water storage tank 101.
In addition, the storage water heater 1 executes a recirculation operation in which hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101. This helps to improve the uniformity of hot water temperature in the hot-water storage tank 101, and mitigate a decrease in hot water temperature in the lower part of the hot-water storage tank.
If the hot water in the upper part of the hot-water storage tank 101 has dropped in temperature, to increase sterilization effect, the controller 300 may, in executing the recirculation operation, activate the heat pump unit 200 so that hot water drawn from the upper part of the hot-water storage tank 101 is heated before the hot water is delivered to the lower part of the hot-water storage tank 101. Even through the heating device is used in this case, the hot water from the upper part of the hot-water storage tank 101 has a higher temperature than the hot water in the lower part of the hot-water storage tank 101, and thus is heated with comparatively less energy. This allows hygiene to be efficiently maintained in an energy-saving manner in the lower part of the hot-water storage tank 101 and in the passage 11, which is connected from the lower part of the hot-water storage tank 101 to the upper part of the hot-water storage tank 101.
The controller 300 is configured to cause the above-mentioned recirculation operation to be executed, for example, at regular intervals when high-temperature hot water is stored in the upper part of the hot-water storage tank 101. Alternatively, the controller 300 may be configured to cause the recirculation operation to be executed when, after the heat-up operation, no hot water is used and thus no tap water is supplied. Whether hot water has been used is determined by the controller 300 through, for example, transmission of measurement results to the controller 300, the measurement results including a measurement result of hot water temperature obtained by a water temperature meter (not illustrated) in the hot-water storage tank 101 and measurement results obtained by the thermistor 131 and the thermistor 132.
The controller 300 may be configured to perform the recirculation operation immediately after the heat-up operation. Immediately after the hating-up operation, hot water in the hot-water storage tank 101 may have a temperature difference between the upper and lower parts of the hot-water storage tank 101. To decrease such a difference, executing the recirculation operation immediately after the heat-up operation makes it possible to mitigate a decrease in hot water temperature in the lower part of the hot-water storage tank 101. This makes it possible to sterilize under high temperature, or disinfect under running water, the lower part of the hot-water storage tank 101 and the interior of the passage 11, which is connected from the lower part of the hot-water storage tank 101 to the upper part of the hot-water storage tank 101.
The storage water heater according to Embodiment 1 executes a recirculation operation in which, after the heat-up operation, hot water drawn from the upper part of the hot-water storage tank is delivered to the lower part of the hot-water storage tank. This makes it possible to, in an energy-saving manner, efficiently inhibit microbial growth and improve the maintenance of hygiene in the lower part of the hot-water storage tank and in a passage connected to the lower part of the hot-water storage tank.
The recirculation operation mentioned above also helps to improve the uniformity of hot water temperature in the hot-water storage tank, and mitigate a decrease in hot water temperature in the lower part of the hot-water storage tank.
In the following description of Embodiment 2, components or elements identical to those according to Embodiment 1 of the present disclosure are provided with the same reference signs, and features identical or corresponding to those according to Embodiment 1 are not described. A storage water heater 2 according to Embodiment 2 is described below with reference to the drawings.
As illustrated in
The passage 12 connecting the upper and lower parts of the hot-water storage tank 101 includes the following passages in a location external to the hot-water storage tank 101: the first passage 111, the second passage 112, the third passage 113, and the fourth passage 114. The circulation pump 102, the three-way valve 104, the three-way valve 105, and the heat pump unit 200 are disposed in the passage 12.
The storage water heater 2 according to Embodiment 2 includes a controller 302. The controller 302 selectively switches between the heat-up operation and the recirculation operation, and controls how the switching unit (the three-way valve 104 and the three-way valve 105), the circulation pump 102, and the heat pump unit 200 operate during each of these operations.
The three-way valve 104 and the three-way valve 105 each include three water inlet-outlet ports through which hot water flows in and out. The three-way valve 104 includes a first water inlet-outlet port 4a, a second water inlet-outlet port 4b, and a third water inlet-outlet port 4c. The three-way valve 105 includes a first water inlet-outlet port 5d, a second water inlet-outlet port 5e, and a third water inlet-outlet port 5f.
The first water inlet-outlet port 4a of the three-way valve 104 and the first water inlet-outlet port 5d of the three-way valve 105 are connected to the first passage 111. The first water inlet-outlet port 4a and the first water inlet-outlet port 5d are thus connected via the first passage 111 to the second inlet-outlet port 101b located in the lower part of the hot-water storage tank 101.
The second water inlet-outlet port 4b of the three-way valve 105 is connected to the second passage 112. The second water inlet-outlet port 4b is thus connected via the circulation pump 102 to the hot-water inlet portion of the heat pump unit 200. The second water inlet-outlet port 5e of the three-way valve 105 is connected to the third passage 113. The second water inlet-outlet port 5e is thus connected via the third passage 113 to the hot-water outlet portion of the heat pump unit 200.
The third water inlet-outlet port 4c of the three-way valve 104 and the third water inlet-outlet port 5f of the three-way valve 105 are both connected to the fourth passage 114. The third water inlet-outlet port 4c and the third water inlet-outlet port 5f are thus connected, via the fourth passage 114 and via the branch part 114a located at a point in the fourth passage 114, to the first inlet-outlet port 101a located in the upper part of the hot-water storage tank 101.
<Heat-Up Operation>
A heat-up operation to be performed by the storage water heater 2 according to Embodiment 2 is described below with reference to
An exemplary heat-up operation is described below in which hot water drawn from the lower part of the hot-water storage tank 101 is routed through the passage 12 and heated by the heat pump unit 200 before the hot water is delivered to the upper part of the hot-water storage tank 101. In
In executing the heat-up operation, the controller 302 controls the three-way valve 104 and the three-way valve 105 such that the first water inlet-outlet port 4a and the second water inlet-outlet port 4b of the three-way valve 104 communicate with each other, and that the second water inlet-outlet port 5e and the third water inlet-outlet port of the three-way valve 105 communicate with each other. At this time, the three-way valve 104 and the three-way valve 105 are switched to a heat-up operation state in which the first passage 111 and the second passage 112 communicate with each other and in which the third passage 113 and the fourth passage 114 communicate with each other.
With the three-way valve 104 and the three-way valve 105 controlled in this manner, the controller 302 activates the circulation pump 102. Consequently, in the passage 12, hot water is sequentially introduced from the second inlet-outlet port 101b, which is located in the lower part of the hot-water storage tank 101, to the first passage 111, the first water inlet-outlet port 4a of the three-way valve 104, the second water inlet-outlet port 4b, the second passage 112, the circulation pump 102, the heat pump unit 200, the third passage 113, the second water inlet-outlet port 5e of the three-way valve 105, the third water inlet-outlet port 5f, the fourth passage 114, and then to the first inlet-outlet port 101a, which is located in the upper part of the hot-water storage tank 101.
The controller 302 controls the heat pump unit 200 such that the heat pump unit 200 heats hot water flowing into the inlet portion of the heat pump unit 200, and causes the heated hot water to flow out toward the outlet portion of the heat pump unit 200.
In this manner, a heat-up operation is executed in which hot water drawn from the lower part of the hot-water storage tank 101 is heated by the heat pump unit 200 serving as a heating device and then the heated hot water is delivered to the upper part of the hot-water storage tank 101.
Through the heat-up operation mentioned above, in the up-and-down direction of the hot-water storage tank 101, hot water at high temperature is gradually stored into the hot-water storage tank 101 from the upper part of the hot-water storage tank 101 as a layer over hot water at low temperature located in the lower part.
<Recirculation Operation>
A recirculation operation to be performed by the storage water heater 2 according to Embodiment 2 is described below with reference to
The storage water heater 2 according to Embodiment 2 operates in substantially the same manner as with Embodiment 1 when hot water is to be used at the bathtub 400 or the hot-water supply end 124 after the heat-up operation mentioned above. That is, hot water drawn from the first inlet-outlet port 101a in the upper part of the hot-water storage tank 101 is routed through the fourth passage 114, where the hot water is mixed at the mixing valve 121 or the mixing valve 122 with tap water supplied from the water supply end 120. The hot water thus becomes warm water, which is then supplied to the hot-water supply end 124 or the bathtub 400. In this case, as the warm water obtained by the mixing is supplied to an external location, tap water is supplied via the fifth passage 115 from the water supply end 120 into the hot-water storage tank 101 through the water supply port 101c. In
After the heat-up operation, a recirculation operation is executed in which hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101.
In the recirculation operation performed by the storage water heater 2 as well, hot water is routed through the passage 12. In
In executing the recirculation operation, the controller 302 controls the three-way valve 104 and the three-way valve 105 such that the second water inlet-outlet port 4b and the third water inlet-outlet port 4c of the three-way valve 104 communicate with each other, and that the first water inlet-outlet port 5d and the second water inlet-outlet port 5e of the three-way valve 105 communicate with each other. At this time, the three-way valve 104 and the three-way valve 105 are switched to a recirculation operation state in which the fourth passage 114 and the second passage 112 communicate with each other and in which the third passage 113 and the first passage 111 communicate with each other.
With the three-way valve 104 and the three-way valve 105 controlled in this manner, the controller 302 activates the circulation pump 102. Consequently, in the passage 12, hot water is sequentially introduced from the first inlet-outlet port 101a, which is located in the upper part of the hot-water storage tank 101, to the fourth passage 114, the third water inlet-outlet port 4c of the three-way valve 104, the second water inlet-outlet port 4b, the second passage 112, the circulation pump 102, the heat pump unit 200, the third passage 113, the second water inlet-outlet port 5e of the three-way valve 105, the first water inlet-outlet port 5d, the first passage 111, and then to the second inlet-outlet port 101b, which is located in the lower part of the hot-water storage tank 101.
In this manner, hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101.
At this time, the controller 302 causes the heat pump unit 200 to stop heating, and allows only passage of water through the heat pump unit 200. In this manner, a recirculation operation is executed in which high-temperature hot water drawn from the upper part of the hot-water storage tank 101 is delivered to and circulated in the lower part of the hot-water storage tank 101. Executing such a recirculation operation causes the temperature in the lower part of the hot-water storage tank 101 to rise to a temperature that limits microbial growth. The recirculation operation also makes it possible to sterilize under high temperature, or disinfect under running water, the interiors of the following components disposed in the passage 12 connected from the lower part of the hot-water storage tank 101 to the upper part of the hot-water storage tank 101: the first passage 111, the second passage 112, the third passage 113, the fourth passage 114, the three-way valve 104, the three-way valve 105, the circulation pump 102, and the heat pump unit 200.
As with Embodiment 1, in executing the recirculation operation mentioned above, the heat pump unit 200 is activated to deliver hot water drawn from the upper part of the hot-water storage tank 101 to the lower part of the hot-water storage tank 101. This allows for improved sterilization effect.
In the following description of Embodiment 3, components or elements identical to those according to Embodiment 1 of the present disclosure are provided with the same reference signs, and features identical or corresponding to those according to Embodiment 1 are not described. A storage water heater 3 according to Embodiment 3 is described below with reference to the drawings.
As illustrated in
The flow sensor 127 is disposed between the branch part 115a of the fifth passage 115 connected to the water supply end 120, and the second inlet-outlet port 101b of the hot-water storage tank 101. The tap water to be supplied to the hot-water storage tank 101 passes through the fifth passage 115 and the branch part 115a. The flow sensor 127 may be disposed at any location other than the above-mentioned location as long as the flow sensor 127 is configured to measure the amount of tap water charged into the hot-water storage tank 101.
All of the flow sensors 125, 126, and 127 may be provided, or only one of these flow sensors may be provided as required.
The storage water heater 3 according to Embodiment 3 includes a controller 303. The controller 303 controls a heat-up operation, a recirculation operation, and the switching action of the four-way valve 103 serving as a switching unit.
A heat-up operation performed by the storage water heater 3 is substantially the same as the heat-up operation performed by the storage water heater 1 according to Embodiment 1, and thus not described below.
As with Embodiment 1, the storage water heater 3 according to Embodiment 3 likewise executes, after the heat-up operation, a recirculation operation in which hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101. The following describes how the recirculation operation performed by the storage water heater 3 according to Embodiment 3 differs from the recirculation operation according to Embodiment 1.
<Recirculation Operation>
In the storage water heater 3 according to Embodiment 3, the controller 303 controls the recirculation operation depending on the amount of tap water that is supplied to the hot-water storage tank 101.
The amount of warm water supplied to an external location at the hot-water supply end 124 is measured by the flow sensor 125 disposed in correspondence with the hot-water supply end 124. At this time, the temperature of warm water is measured by the thermistor 131. The measurement results obtained by the flow sensor 125 and the thermistor 131 are sent to the controller 303. Since a heat quantity is calculated as the product of temperature and the amount of water, the heat quantity of warm water supplied to the hot-water supply end 124 is calculated from the measured amount of warm water and the measured temperature of warm water. The controller 303 thus computes the amount of hot water that has been drawn from the upper part of the hot-water storage tank 101, and estimates the amount of tap water that has been charged into the hot-water storage tank 101.
The amount of warm water supplied to an external location at the bathtub 400 is measured by the flow sensor 126 disposed in correspondence with the bathtub 400. At this time, the temperature of warm water is measured by the thermistor 132. The measurement results obtained by the flow sensor 126 and the thermistor 133 are sent to the controller 303. The heat quantity of warm water supplied to the bathtub 400 is calculated from the measured amount of warm water and the measured temperature of warm water. The controller 303 thus computes the amount of hot water that has been drawn from the upper part of the hot-water storage tank 101, and estimates the amount of tap water that has been charged into the hot-water storage tank 101.
That is, the amount and temperature of warm water supplied to an external location are measured by using each of the flow sensors 125 and 126 as a water flow detection unit and by using each of the thermistors 131 and 132 as a warm-water-temperature detection unit. The heat quantity of warm water supplied to an external location is calculated on the basis of the measurement results of the amount and temperature of warm water, and the amount of hot water that has been drawn from the hot-water storage tank 101 is thus computed. The amount of tap water supplied to the hot-water storage tank 101 is estimated from the amount of hot water that has been drawn from the hot-water storage tank 101.
Alternatively, the amount of hot water that has been drawn from the hot-water storage tank 101 may be directly measured by a flow sensor or other suited sensor.
In a case in which the flow sensor 127 is to be used as a water flow detection unit for tap water, the amount of tap water supplied to the hot-water storage tank 101 is measured directly. The measurement result obtained by the flow sensor 127 is sent to the controller 303.
The controller 303 may calculate the amount of tap water supplied to the hot-water storage tank 101 from measurement information individually obtained by the flow sensors 125, 126, and 127, or may calculate the amount of tap water supplied to the hot-water storage tank 101 more accurately by combining the measurement results obtained by these flow sensors.
According to Embodiment 3, the duration of the recirculation operation is controlled depending on the amount of tap water supplied to the hot-water storage tank 101. More specifically, the controller 303 controls the recirculation operation such that the duration for which the circulation pump 102 is to be operated during the recirculation operation increases with increasing amount of tap water supplied to the hot-water storage tank 101, and that the duration for which the circulation pump 102 is to be operated during the recirculation operation decreases with decreasing amount of tap water supplied to the hot-water storage tank 101.
This makes continuous circulation unnecessary, and allows for reduced duration of the recirculation operation in comparison to Embodiment 1. The controller 303 allows the heat pump unit 200 to be operated depending on the amount of tap water charged into the hot-water storage tank 101. This enables efficient execution of the recirculation operation.
The storage water heater according to Embodiment 3 provides substantially the same advantageous effect as that of the storage water heater according to Embodiment 1.
Further, the recirculation operation is controlled depending on the amount of tap water supplied to the hot-water storage tank. This allows for improved efficiency of the recirculation operation.
In the following description of Embodiment 4, components or elements identical to those according to Embodiment 1 of the present disclosure are provided with the same reference signs, and features identical or corresponding to those according to Embodiment 1 are not described. A storage water heater 4 according to Embodiment 4 is described below with reference to the drawings.
As illustrated in
Although the thermistors 133, 134, and 135 are illustrated in
The storage water heater 4 according to Embodiment 4 includes a controller 304. The controller 304 controls a heat-up operation, a recirculation operation, and the switching action of the four-way valve 103 serving as a switching unit.
A heat-up operation performed by the storage water heater 4 is substantially the same as the heat-up operation performed by the storage water heater 1 according to Embodiment 1, and thus not described below.
As with Embodiment 1, the storage water heater 4 according to Embodiment 4 likewise executes, after the heat-up operation, a recirculation operation in which hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101. The following describes how the recirculation operation performed by the storage water heater 4 according to Embodiment 4 differs from the recirculation operation according to Embodiment 1.
<Recirculation Operation>
In the storage water heater 4 according to Embodiment 4, the temperature of hot water stored in the hot-water storage tank 101 is detected by each of the thermistors 133, 134, and 135 serving as a hot-water-temperature detection unit, and the temperature detected by each thermistor is sent to the controller 304. The controller 304 controls the recirculation operation depending on the temperature of hot water stored in the hot-water storage tank 101.
The controller 304 is configured to cause the recirculation operation to be continued to keep the temperature of hot water stored in the hot-water storage tank 101 outside a predetermined temperature range. A predetermined temperature range that tends to facilitate microbial growth is defined in advance, and the recirculation operation is executed such that the temperature of stored hot water is outside the predetermined temperature range. For example, the circulation pump 102 is continued to operate to ensure that the temperatures detected by the thermistors 133, 134, and 135 be outside a range of 20 to 40 degrees C.
In a case in which the temperatures detected by the thermistors 133 and 134 drop, and the temperature detected by the thermistor 135 located in the lower part of the hot-water storage tank 101 does not become higher than 40 degrees C. even when the recirculation operation is executed, the controller 304 activates the heat pump unit 200 to enable efficient execution of the recirculation operation.
A thermistor may be disposed only in the lower part of the hot-water storage tank 101 as a hot-water-temperature detection unit to detect the temperature of hot water in the lower part. In this case, the recirculation operation is controlled such that the temperature of hot water in the lower part of the hot-water storage tank 101 is outside the range of 20 to 40 degrees C.
The storage water heater according to Embodiment 4 provides substantially the same advantageous effect as that of the storage water heater according to Embodiment 1.
Further, the recirculation operation is controlled depending on the temperature of hot water in the hot-water storage tank. This leads to improved efficiency of the recirculation operation.
In the following description of Embodiment 5, components or elements identical to those according to Embodiment 1 of the present disclosure are provided with the same reference signs, and features identical or corresponding to those according to Embodiment 1 are not described. A storage water heater 5 according to Embodiment 5 is described below with reference to the drawings.
As illustrated in
The tap-water-temperature detection unit to be used, and its location are not limited to those mentioned above as long as the temperature of hot water supplied to the hot-water storage tank 101 is detected.
The storage water heater 5 according to Embodiment 5 includes a controller 305. The controller 305 controls a heat-up operation, a recirculation operation, and the switching action of the four-way valve 103 serving as a switching unit.
A heat-up operation performed by the storage water heater 5 is substantially the same as the heat-up operation performed by the storage water heater 1 according to Embodiment 1, and thus not described below.
As with Embodiment 1, the storage water heater 5 according to Embodiment 5 likewise executes, after the heat-up operation, a recirculation operation in which hot water drawn from the upper part of the hot-water storage tank 101 is delivered to the lower part of the hot-water storage tank 101. The following describes how the recirculation operation performed by the storage water heater 5 according to Embodiment 5 differs from the recirculation operation according to Embodiment 1.
<Recirculation Operation>
In the storage water heater 5 according to Embodiment 5, the temperature of tap water supplied to the hot-water storage tank 101 is detected by the thermistor 136 serving as a tap-water-temperature detection unit, and the temperature detected by the thermistor 136 is sent to the controller 305. The controller 305 controls the recirculation operation depending on the temperature of tap water supplied to the hot-water storage tank 101.
More specifically, the controller 305 controls the recirculation operation as described below. The higher the environmental temperature because of the season or other factors, and the higher the temperature of tap water detected by the thermistor 136, the shorter the duration for which the circulation pump 102 is to be operated during the recirculation operation. The lower the environmental temperature because of the season or other factors, and the lower the temperature of tap water detected by the thermistor 136, the longer the duration for which the circulation pump 102 is to be operated during the recirculation operation. In this manner, the duration of the recirculation operation is controlled depending on the detected temperature of tap water. This allows for improved efficiency of the recirculation operation.
The controller 305 may, in response to changes in environmental temperature, activate the heat pump unit 200 when the temperature of tap water is below a predetermined temperature, such as in winter. This enables efficient execution of the recirculation operation.
It is also possible to combine different embodiments with each other. For example, the storage water heater 5 may be used in combination with the thermistors according to Embodiment 4 that are disposed in the interior of the hot-water storage tank 101. In this case, the operation of the circulation pump 102 and the operation of the heat pump unit 200 are controlled depending on the detected temperature of hot water stored in the hot-water storage tank 101 and the detected temperature of tap water supplied to the hot-water storage tank 101. This enables efficient execution of the recirculation operation.
The storage water heater according to Embodiment 5 provides substantially the same advantageous effect as that of the storage water heater according to Embodiment 1.
Further, the recirculation operation is controlled depending on the detected temperature of tap water being supplied. This enables efficient execution of the recirculation operation.
The features described above with reference to the embodiments are representative of one example of the present disclosure. These features may be combined with other known techniques, or different embodiments may be combined with each other. The features may be partially omitted or modified without departing from the spirit and scope of the present disclosure. The above-mentioned embodiments are intended to be illustrative of the present disclosure, rather than restrictive of the scope of the present disclosure.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/002298 | 1/22/2021 | WO |
