water heater

Abstract

To provide a water heater capable of further stabilizing a hot water supply temperature in a general hot water supply passage even when simultaneous hot water supply in a bath hot water supply passage is started during hot water supply in the general hot water supply passage.SOLUTION: A water heater includes a hot water storage unit and a heat source unit. The hot water storage unit includes: a hot water storage tank that stores hot water supplied from the heat source unit; a first mixing valve for mixing the hot water supplied from the hot water storage tank with water supplied from outside and causing the mixture to flow into a general hot water supply passage side; a second mixing valve for mixing the hot water supplied from the hot water storage tank with water supplied from outside and causing the mixture to flow into a bath hot water supply passage side; and a control section that controls valve openings of the first mixing valve and the second mixing valve. When hot water is simultaneously supplied to the general hot water supply passage side and the bath hot water supply passage side, the control section alternately starts first control for increasing the valve opening of the first mixing valve and second control for increasing the valve opening of the second mixing valve.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a water heater capable of simultaneously supplying hot water to a general hot water supply line and a bath hot water supply line. [Background technology]

[0002] The automatic hot water supply device disclosed in Patent Document 1 is known as a hot water supply device that can simultaneously supply hot water to both a general hot water supply line connected to a kitchen faucet or a bath shower, and a bath hot water supply line connected to a bathtub. For example, the abstract of this document states that the problem is to "obtain an automatic hot water supply device that can stably control the hot water temperature supplied from a high-priority mixing valve (for example, a shower) even when the operating conditions of the high-priority mixing valve (for example, a shower) change."

[0003] Furthermore, paragraph 0050 of the same document states, "Figure 9 is a diagram showing the relationship between the opening of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the general hot water supply temperature and the bath hot water supply temperature when the simultaneous hot water supply correction coefficient Km is not applied to the opening control of the bath hot water supply side mixing valve 2b (which has a lower priority). (a) shows the relationship between the opening of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the elapsed time, and (b) shows the relationship between the general hot water supply temperature and the bath hot water supply temperature and the elapsed time." Furthermore, Figure 10 shows the relationship between the opening of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the general hot water supply temperature and the bath hot water supply temperature when the simultaneous hot water supply correction coefficient Km is applied to the opening control of the bath hot water supply side mixing valve 2b (the one with the lower priority), where (a) shows the relationship between the opening of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b and the elapsed time, and (b) shows the relationship between the general hot water supply temperature and the bath hot water supply temperature and the elapsed time.

[0004] Furthermore, paragraph 0051 of the same document states, "When the simultaneous hot water supply correction coefficient Km is not applied, the opening degrees of the general hot water supply side mixing valve 2a and the bath hot water supply side mixing valve 2b are controlled independently, so the opening degree of the bath hot water supply side mixing valve 2b is too large, resulting in a large amount of undershoot in the general hot water temperature. However, when the simultaneous hot water supply correction coefficient Km is applied, as the general hot water supply en (deviation between the set temperature and the actual hot water temperature) increases, the amount of change in the opening degree of the bath hot water supply side mixing valve 2b becomes smaller, and the amount of undershoot in the general hot water temperature becomes smaller."

[0005] In this way, in the automatic hot water supply device of Patent Document 1, undershoot of the general hot water temperature that occurs when the driving conditions of the mixing valve change (such as when the set temperature of the bath hot water supply is increased) is suppressed by applying the simultaneous hot water supply correction coefficient Km to the opening control of the mixing valve (see Figures 9 and 10 of the same document). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-267692 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the undershoot of the general hot water temperature in Figure 10 of Patent Document 1 is suppressed compared to Figure 9 of the same document, it continues for a considerable period of time, and general hot water supply at a temperature lower than the set temperature continues for a considerable period of time, so it cannot be said that the issue of stabilizing the hot water temperature, which is the problem of Patent Document 1, has been fully achieved.

[0008] Therefore, the present invention aims to provide a water heater that can more stabilize the hot water temperature in the general hot water supply line even when hot water supply to the bath hot water supply line is started simultaneously while hot water supply to the general hot water supply line is started. [Means for solving the problem]

[0009] In order to solve the above problems, the water heater of the present invention is a water heater having a hot water storage unit and a heat source unit, wherein the hot water storage unit has a hot water storage tank for storing hot water supplied from the heat source unit, a first mixing valve for mixing the hot water supplied from the hot water storage tank with water supplied from the outside and discharging the mixture to the general hot water supply path side, a second mixing valve for mixing the hot water supplied from the hot water storage tank with water supplied from the outside and discharging the mixture to the bath hot water supply path side, and a control unit for controlling the valve opening of the first mixing valve and the second mixing valve, wherein the control unit, when supplying hot water to the general hot water supply path side and the bath hot water supply path side simultaneously, alternately initiates a first control for increasing the valve opening of the first mixing valve and a second control for increasing the valve opening of the second mixing valve. [Effects of the Invention]

[0010] According to the water heater of the present invention, the hot water temperature in the general hot water supply line can be more stabilized even when hot water supply to the bath hot water supply line is started simultaneously while hot water supply to the general hot water supply line is being started. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a water heater according to a first embodiment. [Figure 2] 4 is a graph showing valve opening control of a mixing valve by the water heater of Example 1. [Figure 3] 3 is a graph showing the effect of the valve opening control in FIG. 2; [Figure 4] 6 is a graph showing valve opening control of a mixing valve by a water heater according to a second embodiment. [Figure 5] 5 is a graph showing the effect of the valve opening control of FIG. 4. [Figure 6] 10 is a graph showing valve opening control of a mixing valve by a water heater according to a third embodiment. [Figure 7] 7 is a graph showing the effect of the valve opening control of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of a water heater 100 according to the present invention will be described with reference to the drawings. [Example]

[0013] Fig. 1 is a schematic diagram of a water heater 100 according to one embodiment. As shown here, the water heater 100 is a device in which a hot water storage unit 1 and a heat source unit 2 are connected by piping, and the hot water storage unit 1 and an operation unit 3 are connected so as to be able to communicate with each other. A mixing faucet 4 is also provided outside the water heater 100. Each of these will be explained in turn below.

[0014] <Heat source unit 2> The heat source unit 2 is a device that boils water at room temperature (for example, 20°C) to produce hot water at high temperature (for example, 60°C). Note that, since a well-known heat source such as a heat pump can be used as the heat source unit 2 of this embodiment, detailed explanation of the heat source unit 2 will be omitted below.

[0015] <Operation Unit 3> The operation unit 3 is a user interface that the user operates to set the temperatures of the general hot water supply and the bath hot water supply separately, and to start automatic bath filling. In the following, the set temperature of the general hot water supply set by the user will be referred to as Ta, and the set temperature of the bath hot water supply set by the user will be referred to as Tb.

[0016] <Hot water storage unit 1> The hot water storage unit 1 is a device that supplies hot water according to a set temperature to the general hot water supply line and the bath hot water supply line, and has the function of supplying water at room temperature to the heat source unit 2 and the function of storing high-temperature hot water supplied from the heat source unit 2. As shown in the figure, this hot water storage unit 1 has a hot water storage tank 11, a pressure reducing valve 12, mixing valves 13a and 13b, a solenoid valve 14, temperature sensors 15a to 15d, and a control unit 16, and each component is connected by piping as shown in the figure.

[0017] Although not shown, each of mixing valves 13a, 13b and solenoid valve 14 is provided with a drive unit that controls the valve opening of each valve, and communication lines are wired to transmit commands from control unit 16 to each drive unit. Communication lines are also wired to transmit temperatures measured by temperature sensors 15a to 15d to control unit 16.

[0018] Hot water storage tank 11 is a container that stores hot water supplied from heat source unit 2 in an upper portion and water supplied from the water supply in a lower portion. Note that there is no partition inside hot water storage tank 11 to separate the hot water from the water storage, and the hot water is configured so that hot water accumulates in the upper portion of hot water storage tank 11 and water accumulates in the lower portion as the relatively lighter hot water moves upward and the relatively heavier water moves downward, and therefore the height of the hot water / water boundary changes from time to time depending on the amount of remaining hot water.

[0019] The pressure reducing valve 12 reduces the pressure of high-pressure water supplied from the waterworks and supplies the water to the hot water storage tank 11 and the mixing valves 13a and 13b.

[0020] Mixing valve 13a mixes high-temperature hot water supplied from the top of hot water storage tank 11 with water supplied from the mains via pressure reducing valve 12, produces hot water at a desired temperature, and supplies it to the mixing faucet. Similarly, mixing valve 13b mixes high-temperature hot water supplied from the top of hot water storage tank 11 with water supplied from the mains via pressure reducing valve 12, produces hot water at a desired temperature, and supplies it to solenoid valve 14.

[0021] For example, if 60°C hot water is supplied from the hot water storage tank 11 and 20°C water is supplied from the tap, and the set hot water temperature is 40°C, the valve opening of each mixing valve can be controlled so that the inflow ratio is 50:50 hot water:50 cold water, thereby making the temperature of the hot water flowing out of each mixing valve 40°C. For simplicity's sake, the valve opening in the following explanation refers to the valve opening on the hot water side. Therefore, to find the valve opening on the cold water side, simply subtract the value of the valve opening on the hot water side (0 to 100) from 100.

[0022] Solenoid valve 14 switches whether or not hot water from mixing valve 13b is supplied to the bath hot water supply line. That is, when solenoid valve 14 is open, hot water is supplied to the bath hot water supply line, and when solenoid valve 14 is closed, hot water is not supplied to the bath hot water supply line.

[0023] Temperature sensor 15a measures the temperature of the hot water immediately after it flows out of mixing valve 13a and notifies control unit 16. Temperature sensor 15b measures the temperature of the hot water immediately after it flows out of mixing valve 13b and notifies control unit 16. Temperature sensor 15c measures the temperature of the hot water immediately after it flows out of hot water storage tank 11 and notifies control unit 16. Temperature sensor 15d measures the temperature of water supplied from the water supply and notifies control unit 16. In the following, the temperatures measured by temperature sensors 15a to 15d will be referred to as Ta' to Td', respectively.

[0024] The control unit 16 feedback-controls the valve openings of the mixing valves 13a and 13b so that the measured temperature becomes the set temperature. For example, when supplying hot water only to the general hot water supply line, the control unit 16 feedback-controls the valve opening of the mixing valve 13a to reduce the error ΔTa, based on the error ΔTa between the set temperature Ta and the measured temperature Ta' and the error between the measured temperature Tc' and the measured temperature Td'. When supplying hot water only to the bath hot water supply line, the control unit 16 feedback-controls the valve opening of the mixing valve 13b to reduce the error ΔTb, based on the error ΔTb between the set temperature Tb and the measured temperature Tb' and the error between the measured temperature Tc' and the measured temperature Td'. When supplying hot water simultaneously to both the general hot water supply line and the bath hot water supply line, the control unit 16 performs the valve opening control described with reference to Figures 2 and 3 to stabilize the hot water temperature of the general hot water supply line, which has a higher priority.

[0025] <Mixer faucet 4> The mixer tap 4 is a tap that mixes hot water from the mixer valve 13a with water from the tap and supplies it to a faucet or shower in the general hot water supply line, and is operated by the user when making final adjustments to the hot water temperature.

[0026] <Mixing valve control when simultaneously supplying hot water> If hot water supply to the bath starts while hot water is being supplied to the general hot water supply line (for example, while a user is taking a shower), the hot water that had previously been supplied only to mixing valve 13a on the general hot water supply line from hot water storage tank 11 will now also be supplied to mixing valve 13b on the bath hot water supply line. Therefore, the pressure of the hot water supplied to mixing valve 13a temporarily drops until the hot water flows in both directions stabilize. This temporary drop in hot water pressure temporarily disrupts the balance between hot and cold water pressure at mixing valve 13a, causing the water pressure to increase relatively. This temporarily lowers the temperature of the hot water flowing out of mixing valve 13a (measured temperature Ta'). This temporarily lowers the temperature of the hot water downstream of mixing valve 13a, causing problems such as a user taking a shower being temporarily bathed in water that is cooler than usual.

[0027] To avoid such problems, the water heater 100 of this embodiment implements valve opening control, which alternately increases the valve opening of the mixing valve 13a and the valve opening of the mixing valve 13b, when starting to supply hot water to the bath while supplying hot water to the general hot water supply line, as shown in the schematic graph of Figure 2. This valve opening control will be described in detail below.

[0028] First, when simultaneous hot water supply starts, the control unit 16 increases the valve opening of the mixing valve 13a on the general hot water supply line side to increase the amount of hot water flowing into the mixing valve 13a. This keeps the hot water / cold water mixture ratio in the mixing valve 13a approximately constant, and prevents a drop in the temperature of the hot water flowing out of the mixing valve 13a.

[0029] However, if the valve opening of mixing valve 13a is increased to increase the amount of hot water flowing into mixing valve 13a, the amount of hot water flowing into mixing valve 13b on the bath hot water supply line side will decrease as a reaction, and the temperature of the hot water flowing out of mixing valve 13b will drop. Therefore, when the pressure balance of hot and cold water in mixing valve 13a becomes stable, control unit 16 increases the valve opening of mixing valve 13b to increase the amount of hot water flowing into mixing valve 13b, thereby suppressing the drop in the temperature of the hot water flowing out of mixing valve 13b.

[0030] If the valve opening of mixing valve 13b is increased to increase the amount of hot water flowing into mixing valve 13b, the pressure balance of the hot water and water in mixing valve 13a will be disrupted again as a reaction, causing a drop in the temperature of the hot water flowing out of mixing valve 13a to occur again.However, if the valve opening of mixing valve 13a is increased again, the drop in the temperature of the hot water flowing out of mixing valve 13a can be suppressed again, so when the valve opening of mixing valve 13b is increased, the valve opening of mixing valve 13a should also be increased in conjunction with it.

[0031] As can be seen from the above explanation, when bath hot water supply is started while hot water is being supplied to the general hot water supply line, the control unit 16 of this embodiment performs valve opening control that alternates between periods in which the valve opening of the mixing valve 13a on the general hot water supply line side is increased and periods in which the valve opening of the mixing valve 13b on the bath hot water supply line side is increased.

[0032] <Effects of valve opening control in Figure 2> Figure 3 is a graph showing an example of the change in hot water temperature on the general hot water supply path side when the valve openings of mixing valves 13a and 13b are controlled as in Figure 2. The left graph in Figure 3 is a graph showing the change over time in temperature Ta' measured by temperature sensor 15a located immediately after mixing valve 13a, and the right graph in Figure 3 is a graph showing the change over time in temperature of hot water flowing out from a faucet or shower, which is the outlet of the general hot water supply path.

[0033] As shown in the left diagram of Figure 3, a relatively large undershoot occurs in the measured temperature Ta' (hot water temperature immediately after mixing valve 13a) immediately after simultaneous hot water supply begins, but the undershoot quickly converges by controlling the valve opening of mixing valve 13a on the general hot water supply line to increase significantly all at once (see Figure 2). Thereafter, a relatively small undershoot occurs each time the valve opening of mixing valve 13b on the bath hot water supply line is increased, but this undershoot also quickly converges each time the valve opening of mixing valve 13a on the general hot water supply line is increased. Therefore, when the valve opening control shown in Figure 2 is implemented, small undershoots are repeatedly observed in the measured temperature Ta' (hot water temperature immediately after mixing valve 13a), but each undershoot can be quickly converged.

[0034] Here, there is a considerable piping distance from the mixing valve 13a to the faucet (or shower), and the hot water temperature averages out as it flows from the mixing valve 13a to the faucet (or shower). As a result, any undershoot in the temperature of the hot water flowing out of the faucet (or shower) is suppressed to a momentary drop corresponding to the initial relatively large undershoot shown in the left figure of Figure 3, as shown in the right figure of Figure 3. Therefore, users will not be affected by the disadvantages associated with simultaneous hot water supply for a long period of time.

[0035] <Example of valve opening control> Although the valve opening control of this embodiment has been outlined using FIGS. 2 and 3, the valve opening control of FIG. 2 may also be implemented as follows.

[0036] <<First specific control>> The control unit 16 may set the amount of increase in the valve opening of the mixing valve 13a on the general hot water supply path side to be relatively large, and the amount of increase in the valve opening of the mixing valve 13b on the bath hot water supply path side to be relatively small. In other words, the control unit 16 may set the amount of increase in the valve opening of the mixing valve 13a on the general hot water supply path side to be relatively large, and the amount of increase in the valve opening of the mixing valve 13b on the bath hot water supply path side to be relatively small.

[0037] By controlling the valve opening in this manner, priority is given to maintaining the hot water temperature on the general hot water supply line side over the bath hot water supply line side, and a temporary drop in the hot water temperature on the general hot water supply line side can be reduced.

[0038] <<Second specific control>> The control unit 16 may increase the opening of the mixing valve 13a on the general hot water supply line by alternating between a relatively short period t1 during which the opening is increased and a relatively long period t2 during which the opening is maintained. The control unit 16 may increase the opening of the mixing valve 13b on the bath hot water supply line by alternating between a relatively short period t3 during which the opening is increased and a relatively long period t4 during which the opening is maintained. In this case, the control unit 16 may set the control period of the mixing valve 13b on the bath hot water supply line longer than the control period of the mixing valve 13a on the general hot water supply line. For example, if the time t1 is 0.1 seconds and the time t2 is 0.9 seconds, i.e., the control period of the mixing valve 13a is 1.0 seconds, the control period of the mixing valve 13b may be set to 0.2 seconds and 1.8 seconds, i.e., the control period of the mixing valve 13b is 2.0 seconds.

[0039] This allows the control cycles of mixing valve 13a and mixing valve 13b to be synchronized, while the valve opening degree of mixing valve 13a on the general hot water supply line side is changed more frequently, thereby shortening the period during which undershooting of hot water flows out of mixing valve 13a.

[0040] <Effects of this Example> As described above, according to the water heater 100 of this embodiment, the hot water temperature of the general hot water supply line can be more stabilized even when hot water supply to the bath hot water supply line is started simultaneously while hot water supply to the general hot water supply line is started. [Example]

[0041] Second Embodiment Next, a water heater 100 according to a second embodiment of the present invention will be described with reference to Figures 4 and 5. Note that a duplicated description of points common to the first embodiment will be omitted.

[0042] In Example 1, as shown in Figure 2, the valve opening degrees of mixing valves 13a and 13b were approximately the same at the start of simultaneous hot water supply, but in this example, as shown in Figure 4, the valve opening degree at the start of simultaneous hot water supply was set higher on the mixing valve 13a side and lower on the mixing valve 13b side.

[0043] When the initial valve opening degree is set as in this embodiment, the temporary drop in hot water pressure that occurs in the mixing valve 13a on the general hot water supply line side when simultaneous hot water supply starts is smaller than in embodiment 1, and therefore the undershoot that occurs immediately after the start of synchronous hot water supply, as shown in the left diagram of Figure 5, is also smaller than that shown in the left diagram of Figure 3. Therefore, the undershoot in the temperature of the hot water flowing out of the faucet (or shower) can also be suppressed to a negligible level, as shown in the right diagram of Figure 5. [Example]

[0044] Next, a water heater 100 according to a second embodiment of the present invention will be described with reference to Figures 6 and 7. Note that a duplicated description of points common to the above-mentioned embodiments will be omitted.

[0045] In Examples 1 and 2, as shown in Figures 2 and 4, the period in which the valve opening degree of mixing valve 13a is increased and the period in which the valve opening degree of mixing valve 13b is increased are alternately provided. However, as in this embodiment shown in Figure 6, the period in which the valve opening degree of mixing valve 13a is increased and the period in which the valve opening degree of mixing valve 13b is increased may be overlapped.

[0046] By providing such an overlap period, the pulling of hot water toward mixing valve 13b, which occurs when the valve opening of mixing valve 13b on the bath hot water supply line side is increased, can be quickly eliminated by simultaneously increasing the valve opening of mixing valve 13a on the general hot water supply line side.As a result, as shown in the left diagram of Figure 7, the undershoot in the temperature of the hot water flowing out of mixing valve 13a can be further reduced. [Explanation of symbols]

[0047] 100 water heater 1 Hot water storage unit 11 Hot water tank 12 Pressure reducing valve 13a, 13b Mixing valve 14 Solenoid valve 15a, 15b Temperature sensors 16 Control Unit 2 Heat source unit 3 Operation Unit 4 Mixer taps

Claims

1. A water heater having a hot water storage unit and a heat source unit, The hot water storage unit is a hot water storage tank that stores hot water supplied from the heat source unit; a first mixing valve that mixes hot water supplied from the hot water storage tank with water supplied from the outside and flows the mixture into a general hot water supply line; a second mixing valve that mixes hot water supplied from the hot water storage tank with water supplied from the outside and flows the mixture into the bath hot water supply line; a control unit that controls the valve opening degrees of the first mixing valve and the second mixing valve, When hot water is simultaneously supplied to the general hot water supply path side and the bath hot water supply path side, the control unit alternately starts a first control for increasing the valve opening degree of the first mixing valve and a second control for increasing the valve opening degree of the second mixing valve, The water heater is characterized in that the control unit increases the valve opening degree of the first mixing valve in the first control by a larger amount than the valve opening degree of the second mixing valve in the second control.

2. A water heater having a hot water storage unit and a heat source unit, The hot water storage unit is a hot water storage tank that stores hot water supplied from the heat source unit; a first mixing valve that mixes hot water supplied from the hot water storage tank with water supplied from the outside and flows the mixture into a general hot water supply line; a second mixing valve that mixes hot water supplied from the hot water storage tank with water supplied from the outside and flows the mixture into the bath hot water supply line; a control unit that controls the valve opening degrees of the first mixing valve and the second mixing valve, When hot water is simultaneously supplied to the general hot water supply path side and the bath hot water supply path side, the control unit alternately starts a first control for increasing the valve opening degree of the first mixing valve and a second control for increasing the valve opening degree of the second mixing valve, the first control includes a first period during which the valve opening degree of the first mixing valve is increased, and a second period longer than the first period during which the valve opening degree of the first mixing valve is maintained, The water heater is characterized in that the second control comprises a third period in which the valve opening degree of the second mixing valve is increased, and a fourth period longer than the third period in which the valve opening degree of the second mixing valve is maintained.

3. The water heater according to claim 2, The water heater, wherein the sum of the third period and the fourth period in the second control is greater than the sum of the first period and the second period in the first control.

4. The water heater according to claim 2, The hot water heater, wherein the first period in the first control and the third period in the second control overlap.

5. A water heater having a hot water storage unit and a heat source unit, The hot water storage unit is a hot water storage tank that stores hot water supplied from the heat source unit; a first mixing valve that mixes hot water supplied from the hot water storage tank with water supplied from the outside and flows the mixture into a general hot water supply line; a second mixing valve that mixes hot water supplied from the hot water storage tank with water supplied from the outside and flows the mixture into the bath hot water supply line; a control unit that controls the valve opening degrees of the first mixing valve and the second mixing valve, When hot water is simultaneously supplied to the general hot water supply path side and the bath hot water supply path side, the control unit alternately starts a first control for increasing the valve opening degree of the first mixing valve and a second control for increasing the valve opening degree of the second mixing valve, A water heater characterized in that the valve opening degree of the first mixing valve at the start of the simultaneous hot water supply is higher than the valve opening degree of the second mixing valve at the start of the simultaneous hot water supply.

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