Heat source device

Abstract

This technology provides a way to raise the overall temperature of the water in a hot water storage tank while preventing the water temperature at the top of the tank from falling below a predetermined temperature. [Solution] The heat source device comprises a hot water storage tank, an internal heat source for heating the water in the hot water storage tank, a first temperature sensor for detecting the temperature of the water in the hot water storage tank above the internal heat source, circulation piping connected to the lower and upper parts of the hot water storage tank, a circulation pump, and a control unit. The control unit is configured to perform heating control, which operates the internal heat source while the circulation pump is stopped, and circulation control, which operates the circulation pump. The control unit switches between heating control and circulation control based on the temperature detected by the first temperature sensor.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a heat source device.

Background Art

[0002] Patent Document 1 discloses a heat source device. The heat source device includes a hot water storage tank, an internal heat source disposed above the lowermost part of the hot water storage tank in the hot water storage tank for heating the water in the hot water storage tank, a plurality of temperature sensors provided in the hot water storage tank for detecting the temperature of the water in the hot water storage tank, a circulation pipe connected to the lower part and the upper part of the hot water storage tank, a circulation pump for sending water from the lower part of the hot water storage tank to the circulation pipe and sending water from the circulation pipe to the upper part of the hot water storage tank, and a control unit for controlling the operations of the internal heat source and the circulation pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the heat source device as described above, when the circulation pump is operated, the low-temperature water at the lower part of the hot water storage tank may flow into the upper part of the hot water storage tank via the circulation pipe. In that case, there is a risk that the temperature of the hot water supplied from the upper part of the hot water storage tank will decrease due to the mixing of the low-temperature water with the water at the upper part of the hot water storage tank. This specification provides a technology capable of raising the temperature of the water in the hot water storage tank as a whole while suppressing the temperature of the water at the upper part of the hot water storage tank from falling below a predetermined temperature.

Means for Solving the Problems

[0005] A heat source device according to a first embodiment disclosed herein may include: a hot water storage tank; an internal heat source positioned above the bottom of the hot water storage tank for heating the water in the hot water storage tank; a first temperature sensor provided in the hot water storage tank for detecting the temperature of the water in the hot water storage tank above the internal heat source; circulation piping connected to the bottom and top of the hot water storage tank; a circulation pump that sends water from the bottom of the hot water storage tank to the circulation piping and from the circulation piping to the top of the hot water storage tank; and a control unit that controls the operation of the internal heat source and the circulation pump. The control unit may be configured to perform heating control, which operates the internal heat source, and circulation control, which operates the circulation pump, while the circulation pump is stopped. The control unit may switch between the heating control and the circulation control based on the temperature detected by the first temperature sensor.

[0006] According to the above configuration, in heating control, the operation of the internal heat source heats the water above the internal heat source, causing its temperature to rise, while the water below the internal heat source remains unheated and at its original temperature. As a result, a temperature stratification is formed inside the hot water storage tank, with a layer of high-temperature water on top of a layer of low-temperature water. In circulation control, the low-temperature water from the bottom of the hot water storage tank flows into the top of the tank via the circulation pipe, mixing with the high-temperature water layer at the top of the tank. Therefore, inside the hot water storage tank, the volume of the high-temperature water layer increases and the volume of the low-temperature water layer decreases, while the temperature of the high-temperature water layer decreases. Consequently, the temperature of the high-temperature water layer decreases while circulation control is being performed. According to the above configuration, the control unit switches between heating control and circulation control based on the temperature detected by the first temperature sensor, thereby preventing the temperature of the water at the top of the hot water storage tank from falling below a predetermined temperature, while raising the overall temperature of the water in the hot water storage tank.

[0007] In a second embodiment, in the heat source device of the first embodiment, the control unit may operate the internal heat source while operating the circulation pump in the circulation control.

[0008] With the above configuration, it is possible to heat the water above the internal heat source while circulation control is in operation. This reduces the time required to raise the overall temperature of the water in the hot water storage tank.

[0009] In a third embodiment, the heat source device according to the first or second embodiment may further include a water supply pipe for supplying water to the hot water storage tank and a hot water supply pipe for supplying hot water from the hot water storage tank. The point where the hot water supply pipe connects to the hot water storage tank may be located above the point where the downstream end of the circulation pipe connects to the hot water storage tank.

[0010] When the heat source unit performs circulation control, even if the temperature of the water in the upper part of the hot water storage tank decreases as the lower-temperature water flows into the upper part of the hot water storage tank, the water above the point where the lower-temperature water flows into the hot water storage tank (i.e., the point where the downstream end of the circulation piping connects to the hot water storage tank) will not decrease in temperature as easily. With the above configuration, since the point where the hot water supply piping connects to the hot water storage tank is located above the point where the downstream end of the circulation piping connects to the hot water storage tank, it is possible to suppress the decrease in the temperature of the hot water supplied from the hot water supply piping.

[0011] In the fourth embodiment, in the heat source device according to any one of the first to third embodiments described above, the control unit may switch from the heating control to the circulation control when the first temperature sensor detects a temperature of a first switching temperature or higher during the execution of the heating control, or when the temperature detected by the first temperature sensor is lower than the first switching temperature, i.e., a second switching temperature or lower, during the execution of the circulation control, the control unit may switch from the circulation control to the heating control.

[0012] With the above configuration, the second switching temperature, which is the threshold temperature for switching from circulation control to heating control, is set lower than the first switching temperature, which is the threshold temperature for switching from heating control to circulation control. Therefore, frequent switching between heating control and circulation control can be suppressed.

[0013] In a fifth embodiment, the heat source device according to any one of the first to fourth embodiments may further include a second temperature sensor for detecting the temperature of the water sent from the hot water storage tank to the circulation piping. The control unit may terminate the heating control or the circulation control if the second temperature sensor detects a temperature above the heating termination temperature while the heating control or the circulation control is being performed.

[0014] With the above configuration, it is possible to heat up the entire volume of hot water in the hot water storage tank.

[0015] In the sixth embodiment, in the heat source device of the fifth embodiment, the second temperature sensor may be provided in the circulation piping and detect the temperature of the water inside the circulation piping.

[0016] With the above configuration, it is possible to more reliably raise the temperature of all the hot water in the storage tank.

[0017] In the seventh embodiment, in the heat source device of the first to sixth embodiments, the first temperature sensor may detect the temperature of the water in the hot water storage tank below the point where the downstream end of the circulation piping is connected to the hot water storage tank.

[0018] With the above configuration, when the heat source device performs circulation control, the first temperature sensor detects the temperature of the water in the hot water storage tank below the point where cold water flows into the hot water storage tank (i.e., the point where the downstream end of the circulation piping connects to the hot water storage tank). Therefore, the temperature drop at the top of the hot water storage tank due to the inflow of cold water can be accurately detected by the first temperature sensor.

[0019] In the eighth embodiment, the heat source device of any one of the first to seventh embodiments may further include a third temperature sensor provided in the hot water storage tank for detecting the temperature of the water in the hot water storage tank above the point where the downstream end of the circulation piping connects to the hot water storage tank. The control unit may switch from the circulation control to the heating control when the third temperature sensor detects a temperature below the circulation stop temperature while the circulation control is being executed.

[0020] According to the above configuration, even when the temperature of the water above the connection point of the downstream end of the circulation pipe to the hot water storage tank decreases, the switching from circulation control to heating control is performed, so that it is possible to suppress the temperature of the hot water supplied from the upper part of the hot water storage tank from decreasing.

[0021] In a ninth aspect, in the heat source device according to any one of the first to eighth aspects, an external heat source for heating the water flowing through the circulation pipe may be further provided.

[0022] According to the above configuration, by operating the external heat source in a state where the circulation pump is operating, the water at the lower part of the hot water storage tank can be heated by the external heat source and returned to the upper part of the hot water storage tank, and the water in the hot water storage tank can be heated.

[0023] In a tenth aspect, in the heat source device according to the ninth aspect, the external heat source may include a heat pump heat source machine.

[0024] According to the above configuration, the energy efficiency when heating the water in the hot water storage tank using the external heat source can be improved.

Brief Description of Drawings

[0025] [Figure 1] It is a diagram showing the configuration of the heat source device 2 of the embodiment. 7] [Figure 2] It is a flowchart of the process performed by the controller 52 of the heat source device 2 of the embodiment. [Figure 3] It is a diagram schematically showing the temperature distribution of the water in the hot water storage tank 10 when the heating control is being executed in the heat source device 2 of the embodiment. [Figure 4] It is a diagram schematically showing the temperature distribution of the water in the hot water storage tank 10 when the circulation control is being executed in the heat source device 2 of the embodiment. [Figure 5] It is a diagram showing the configuration of the heat source device 4 of the modification. [Figure 6] It is a diagram showing the configuration of the heat source device 6 of another modification. [Modes for carrying out the invention]

[0026] (Examples) As shown in Figure 1, the heat source device 2 according to this embodiment includes a hot water storage tank 10, an internal heat source 20, a first temperature sensor 30, a second temperature sensor 32, circulation piping 40, circulation pump 50, a controller 52, hot water supply piping 60, and cold water supply piping 62. The hot water storage tank 10 is a sealed container that stores water inside and is covered on the outside with an insulating material (not shown). The capacity of the hot water storage tank 10 in this embodiment is, for example, 100 liters.

[0027] The internal heat source 20 is installed in the middle section of the inside of the hot water storage tank 10 and is equipped with a heating element 22 that generates heat when electricity is supplied to it. The internal heat source 20 heats the water stored inside the hot water storage tank 10 by generating heat in the heating element 22. The first temperature sensor 30 is installed inside the hot water storage tank 10 above the internal heat source 20 and can detect the temperature of the water in the upper part of the hot water storage tank 10. The second temperature sensor 32 is installed inside the hot water storage tank 10 below the internal heat source 20 and can detect the temperature of the water in the lower part of the hot water storage tank 10.

[0028] The upstream end of the circulation pipe 40 is below the second temperature sensor 32 and connected to the bottom of the hot water storage tank 10. The downstream end of the circulation pipe 40 is above the first temperature sensor 30 and connected to the top of the hot water storage tank 10. The circulation pump 50 is installed in the circulation pipe 40 and pumps water in the circulation pipe 40 from the upstream side to the downstream side. When the circulation pump 50 operates, water flows from the bottom of the hot water storage tank 10 into the circulation pipe 40, and water also flows from the circulation pipe 40 to the top of the hot water storage tank 10.

[0029] The upstream end of the water supply pipe 62 is connected to a water source (not shown), such as a public water supply. The downstream end of the water supply pipe 62 is connected to the bottom of the hot water storage tank 10, below the connection point between the upstream end of the circulation pipe 40 and the hot water storage tank 10. Alternatively, the downstream end of the water supply pipe 62 may be connected to the bottom of the hot water storage tank 10, above or at the same height as the connection point between the upstream end of the circulation pipe 40 and the hot water storage tank 10. The upstream end of the hot water supply pipe 60 is connected to the top of the hot water storage tank 10, above the connection point between the downstream end of the circulation pipe 40 and the hot water storage tank 10. Alternatively, the upstream end of the hot water supply pipe 60 may be connected to the top of the hot water storage tank 10, below or at the same height as the connection point between the downstream end of the circulation pipe 40 and the hot water storage tank 10. The downstream end of the hot water supply pipe 60 is connected to a hot water supply point (not shown), such as a faucet or shower. When the heat source device 2 supplies hot water, high-temperature water is sent from the top of the hot water storage tank 10 to the hot water supply piping 60, and low-temperature water flows from the water supply piping 62 to the bottom of the hot water storage tank 10.

[0030] In this embodiment, the connection point between the upstream end of the circulation pipe 40 and the hot water storage tank 10, and the connection point between the downstream end of the water supply pipe 62 and the hot water storage tank 10, may be located above or below the bottom of the hot water storage tank 10. Also, the connection point between the downstream end of the circulation pipe 40 and the hot water storage tank 10, and the connection point between the upstream end of the hot water supply pipe 60 and the hot water storage tank 10, may be located below or above the top of the hot water storage tank 10.

[0031] The controller 52 includes a CPU, ROM, RAM, etc. The controller 52 controls the operation of the heat source device 2 by executing various processes according to the program stored in the ROM. When power is supplied to the heat source device 2, the controller 52 executes the process shown in Figure 2.

[0032] In S10, the controller 52 waits until the first temperature sensor 30 detects a temperature below a predetermined heating start temperature (e.g., 55°C). When the first temperature sensor 30 detects a temperature below the heating start temperature (i.e., the result is YES), the process proceeds to S12.

[0033] In S12, the controller 52 starts the operation of the internal heat source 20. As a result, the water in the hot water storage tank 10 is heated by the internal heat source 20. Note that the circulation pump 50 is stopped when the process in S12 is executed. This control, in which the controller 52 operates the internal heat source 20 while the circulation pump 50 is stopped, is also called heating control.

[0034] Figure 3 illustrates the temperature distribution of the water inside the hot water storage tank 10 when the controller 52 is performing heating control. During heating control, the heating element 22 of the internal heat source 20 generates heat, causing the water above the internal heat source 20 to heat up and its temperature to rise. On the other hand, the water below the internal heat source 20 is not heated and remains at its original temperature. Through heating control, a temperature stratification is formed inside the hot water storage tank 10, in which a layer of high-temperature water is stacked on top of a layer of low-temperature water.

[0035] As shown in Figure 2, in S14, the controller 52 waits until the first temperature sensor 30 detects a predetermined first switching temperature (e.g., 60°C) or higher. When the first temperature sensor 30 detects a temperature of YES or higher, the process proceeds to S16.

[0036] In S16, the controller 52 starts the operation of the circulation pump 50. As a result, water flows from the bottom of the hot water storage tank 10 into the circulation pipe 40, and water flows from the circulation pipe 40 to the top of the hot water storage tank 10. This control by the controller 52 to operate the circulation pump 50 is also called circulation control. In other words, in S16, the controller 52 switches from heating control to circulation control. In this embodiment, since the internal heat source 20 is operating when the process in S16 is executed, in circulation control, the controller 52 operates the internal heat source 20 while the circulation pump 50 is operating.

[0037] Figure 4 illustrates the temperature distribution of the water inside the hot water storage tank 10 when the controller 52 is performing circulation control. During circulation control, the cold water at the bottom of the hot water storage tank 10 flows into the top of the tank via the circulation pipe 40, and the cold water from the circulation pipe 40 mixes with the layer of hot water at the top of the tank. As a result, the volume of the layer of hot water increases and the volume of the layer of cold water decreases inside the hot water storage tank 10, and the temperature of the layer of hot water decreases. In this embodiment, the water above the internal heat source 20 is continuously heated by the heat generated by the heating element 22 of the internal heat source 20, but the decrease in water temperature due to the inflow of cold water from the circulation pipe 40 is greater than the increase in water temperature due to heating by the internal heat source 20, so the temperature of the layer of hot water decreases while circulation control is being performed.

[0038] As shown in Figure 2, in S18, the controller 52 determines whether the first temperature sensor 30 detects a temperature below a predetermined second switching temperature (e.g., 55°C). If the first temperature sensor 30 detects a temperature above the second switching temperature (NO), the process proceeds to S20.

[0039] In S20, the controller 52 determines whether the second temperature sensor 32 detects a temperature above a predetermined heating completion temperature (e.g., 60°C). If the second temperature sensor 32 detects a temperature below the heating completion temperature (NO), the process returns to S18.

[0040] In S18, if the first temperature sensor 30 detects a temperature below the second switching temperature (YES), the process proceeds to S22. In S22, the controller 52 stops the circulation pump 50. That is, in S22, the controller 52 switches from circulation control to heating control. After S22, the process returns to S14.

[0041] Through the processes in S14-S22, the controller 52 repeatedly alternately performs heating control and circulation control. When the temperature of the water at the top of the hot water storage tank 10 reaches a first switching temperature (e.g., 60°C) or higher, the controller 52 switches from heating control to circulation control. Conversely, when the temperature of the water at the top of the hot water storage tank 10 falls below a second switching temperature (e.g., 55°C), the controller 52 switches from circulation control to heating control. This allows the water at the top of the hot water storage tank 10 to remain above the second switching temperature (e.g., 55°C) while continuing to heat the water inside the hot water storage tank 10 until the total water temperature in the tank reaches a heating termination temperature (e.g., 60°C) or higher.

[0042] In S20, if the second temperature sensor 32 detects a temperature above the heating end temperature (YES), the process proceeds to S24. In S24, the controller 52 determines whether the first temperature sensor 30 detects a temperature above the heating end temperature. Normally, a temperature stratification is formed inside the hot water storage tank 10, so the temperature detected by the first temperature sensor 30 should be higher than the temperature detected by the second temperature sensor 32. However, if the temperature stratification of the water inside the hot water storage tank 10 is disturbed for some reason, the temperature detected by the first temperature sensor 30 may be lower than the temperature detected by the second temperature sensor 32. For this reason, in this embodiment, a confirmation check is also performed using the first temperature sensor 30 in S24. If the first temperature sensor 30 detects a temperature below the heating end temperature (NO), the process returns to S18. If the first temperature sensor 30 detects a temperature above the heating end temperature (YES), the process proceeds to S26.

[0043] In S26, the controller 52 stops the operation of the circulation pump 50.

[0044] In S28, the controller 52 stops the operation of the internal heat source 20. After S28, the process shown in Figure 2 is completed.

[0045] (modified version) The heat source device 2 is installed in the hot water storage tank 10, as shown in the heat source device 4 in Figure 5, and may include a third temperature sensor 34 that detects the temperature of the water in the hot water storage tank 10 above the connection point between the downstream end of the circulation pipe 40 and the hot water storage tank 10. In this case, the controller 52 may execute the process in S22 in S18 of Figure 2 if the first temperature sensor 30 detects a predetermined second switching temperature (e.g., 55°C) or lower, or if the third temperature sensor 34 detects a predetermined circulation stop temperature (e.g., 55°C) or lower, and execute the process in S20 otherwise.

[0046] In the example shown in Figure 1, the first temperature sensor 30 and the second temperature sensor 32 may be installed inside the hot water storage tank 10 or outside the hot water storage tank 10.

[0047] In the example shown in Figure 5, the second temperature sensor 32 may be installed inside the circulation piping 40 or outside the circulation piping 40. Also, in the example shown in Figure 5, the third temperature sensor 34 may be installed inside the hot water storage tank 10 or outside the hot water storage tank 10.

[0048] The heat source device 2 may further include an external heat source 70 for heating the water flowing through the circulation pipe 40, as shown in the heat source device 6 in Figure 6. The external heat source 70 may be a heat pump, a gas heat source, or a solar heat source.

[0049] The internal heat source 20 does not have to be configured to generate heat through power supply. For example, the internal heat source 20 may be a heat exchanger through which a high-temperature heat transfer medium flows. In this case, the heat exchanger is positioned to pass through the inside of the hot water storage tank 10 and heats the water inside the hot water storage tank 10 through heat exchange with the high-temperature heat transfer medium.

[0050] The heating start temperature in S10 in Figure 2 may be the same as or different from the second switching temperature in S18. Similarly, the heating end temperatures in S20 and S24 may be the same as or different from the first switching temperature in S14.

[0051] In S16 of Figure 2, the controller 52 may start the operation of the circulation pump 50 and stop the operation of the internal heat source 20. In this case, in S22 of Figure 2, the controller 52 may stop the circulation pump 50 and start the operation of the internal heat source 20. In other words, in circulation control, the controller 52 may operate the circulation pump 50 and stop the internal heat source 20.

[0052] (Correspondence) Controller 52 is an example of a control unit.

[0053] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0054] 2, 4, 6: Heat source device 10: Hot water storage tank 20: Internal heat source 22: Heat-generating part 30: First temperature sensor 32: Second temperature sensor 34: Third temperature sensor 40: Circulation piping 50: Circulation pump 52: Controller 60: Hot water piping 62: Water supply piping 70: External heat source

Claims

1. Hot water storage tank and Within the hot water storage tank, an internal heat source is positioned above the lowest part of the hot water storage tank and heats the water in the hot water storage tank, A first temperature sensor is provided in the hot water storage tank and detects the temperature of the water in the hot water storage tank above the internal heat source, The circulation piping connected to the lower and upper parts of the aforementioned hot water storage tank, A circulation pump that sends water from the bottom of the hot water storage tank to the circulation piping and from the circulation piping to the top of the hot water storage tank, It comprises the aforementioned internal heat source and a control unit that controls the operation of the circulation pump, The control unit, With the circulation pump stopped, heating control is performed to operate the internal heat source, The system is configured to perform circulation control for operating the aforementioned circulation pump, The control unit performs switching between the heating control and the circulation control based on the temperature detected by the first temperature sensor. Heat source device.

2. The heat source device according to claim 1, wherein the control unit operates the internal heat source while the circulation pump is operating in the circulation control.

3. A water supply pipe for supplying water to the hot water storage tank, The system further includes hot water supply piping that supplies hot water from the aforementioned hot water storage tank, The point where the hot water supply piping connects to the hot water storage tank is located above the point where the downstream end of the circulation piping connects to the hot water storage tank. The heat source device according to claim 1.

4. The control unit, During the execution of the heating control, if the first temperature sensor detects a temperature above the first switching temperature, the system switches from the heating control to the circulation control. During the execution of the circulation control, if the temperature detected by the first temperature sensor is lower than the first switching temperature (a second switching temperature), the system switches from the circulation control to the heating control. The heat source device according to claim 1.

5. The system further includes a second temperature sensor that detects the temperature of the water sent from the hot water storage tank to the circulation piping, The control unit, If the second temperature sensor detects a temperature above the heating termination temperature while the heating control or circulation control is being executed, the heating control or circulation control is terminated. The heat source device according to claim 1.

6. The second temperature sensor is provided in the circulation piping and detects the temperature of the water inside the circulation piping. The heat source device according to claim 5.

7. The first temperature sensor detects the temperature of the water in the hot water storage tank below the point where the downstream end of the circulation piping connects to the hot water storage tank. The heat source device according to claim 1.

8. The hot water storage tank is further provided with a third temperature sensor that detects the temperature of the water in the hot water storage tank located above the point where the downstream end of the circulation piping connects to the hot water storage tank. The control unit, When the third temperature sensor detects a temperature below the circulation stop temperature while the circulation control is being executed, the system switches from the circulation control to the heating control. The heat source device according to claim 7.

9. The system further includes an external heat source for heating the water flowing through the aforementioned circulation pipe. The heat source device according to claim 1.

10. The aforementioned external heat source includes a heat pump heat source unit. The heat source device according to claim 9.

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