JP4287838B2 - Hot water storage hot water supply system - Google Patents

Description

  The present invention relates to a hot water storage hot water supply system that stores hot water heated by power generation heat, solar heat, or the like in a hot water storage tank and supplies hot water as needed using the hot water stored in the hot water storage tank. In particular, in a hot water storage hot water supply system, when the entire amount of hot water in the hot water storage tank has not been replaced within a predetermined long period of time, the technology that prevents the hot water that has remained in the hot water storage tank from being used for a long time is used as it is. About.

  2. Description of the Related Art A hot water supply system is known that stores hot water heated by power generation heat, solar heat, or the like to supply hot water. Hot water heated by generated heat or solar heat is stored in a hot water tank. During hot water supply operation, if hot water that is hotter than the hot water temperature (hot water set temperature) required at the location where hot water is used is stored in the hot water tank, the hot water sent from the hot water tank and tap water (cold water) are mixed in the mixing unit. The water is then cooled to the required temperature. If hot water at a temperature lower than the hot water temperature (hot water set temperature) required at the location where hot water is used is stored in a hot water storage tank, it is necessary to heat the hot water with a hot water heater, etc. Less heat is required than when heating and supplying hot water. The hot water storage system is highly energy efficient.

In recent years, it has been pointed out that harmful bacteria such as Legionella bacteria may propagate in facilities that store and use water such as hot water tanks. Since these facilities are supplied with chlorinated tap water, the possibility of contamination by bacteria such as Legionella is extremely low. However, since there is no possibility of bacterial contamination, measures need to be taken.
For example, Legionella bacteria are known to grow at 20 to 50 ° C. and to grow most at around 36 ° C. Legionella bacteria are also sensitive to heat, and are known to die in a short time (about 5 minutes) in a temperature environment of 60 ° C. or higher. In the hot water storage type hot water supply system as described above, if the power generation operation and the hot water supply operation are performed at an assumed frequency, the hot water in the hot water storage tank is heated to 60 ° C. or more by the generated heat and the hot water is used. Therefore, there is no need to worry about the growth of bacteria such as Legionella. However, such as when the user is absent and the system has not been used for a long period of time, the hot water in the hot water tank does not reach the temperature required for sterilization (the sterilization temperature) for a long period of time. If the period is not changed, there is no possibility that bacteria will propagate in the hot water tank.

  In order to deal with the above problem, for example, in the hot water storage type hot water supply apparatus of Patent Document 1, the hot water in the hot water tank is heated to raise the temperature, and the sterilization operation is maintained at a sterilizable temperature that can sterilize the bacteria for a certain period of time. Is executed. When the hot water is taken out from the bottom of the hot water tank and returned to the upper part of the hot water tank via an external heating means, as in the hot water storage system of Patent Document 1, the hot water temperature at the lower part of the hot water tank is Prone to low temperatures. Therefore, in the hot water storage type hot water supply apparatus of Patent Document 1, the sterilization operation is executed when the state where the hot water temperature in the lower part of the hot water tank is lower than the sterilizable temperature continues for a predetermined time or longer. According to this, since the sterilization operation is started based on the lower hot water temperature that tends to be the lowest in the hot water tank, the sterilization operation can be executed at an appropriate timing.

JP 2004-150649 A

In the hot water storage type hot water supply system incorporated in the cogeneration system, the amount of electric power stored varies depending on the household, so the amount of stored heat also differs. In the hot water storage hot water supply system incorporated in the solar system, the amount of heat storage varies depending on the weather. Also, the amount of hot water used and the frequency of use vary from home to home. Therefore, in the hot water storage type hot water supply system using power generation heat, solar heat or the like as in Patent Document 1, the amount of heat stored in the hot water storage tank is less than the allowable heat storage amount, and the total amount of hot water in the hot water storage tank exceeds the sterilization temperature. The temperature may not rise. Moreover, even if the amount of hot water used per day is less than the capacity of the hot water tank and a predetermined time (for example, 48 hours) in which it is necessary to worry about the growth of bacteria has passed, the total amount of hot water in the hot water tank does not change. Sometimes.
In the hot water storage hot water supply system of Patent Document 1, a sterilization operation is performed when a predetermined time has elapsed since it was detected that the temperature of the hot water in the lower part of the hot water tank is lower than the sterilization temperature. However, even if a predetermined time elapses after it is detected that the hot water temperature at the lower part of the hot water tank is lower than the sterilization temperature, the hot water in the hot water tank is used and the lower hot water enters before the predetermined time elapses. In other words, the time during which hot water below the sterilization temperature actually stays in the hot water tank is at least shorter than the predetermined time. Therefore, in this case, the sterilization operation is performed at a timing that does not need to be performed yet. In the technique of Patent Document 1, the number of sterilization operations increases unnecessarily, and energy required for the sterilization operation is wasted.
Moreover, in the hot water storage type hot-water supply apparatus of patent document 1, since only the hot water temperature of the lower part of a hot water tank is detected, the hot water temperature of the upper layer cannot be grasped | ascertained. That is, even if the heat storage amount is small and the hot water temperature in the upper layer is lower than the sterilization temperature, this cannot be detected. Furthermore, it is not possible to measure the time during which the upper layer warm water temperature is lower than the sterilization temperature. The residence time of the hot water in the upper layer of the hot water tank is longer than the residence time of the hot water in the lower part. In a household where the amount of hot water used is small, the residence time of the upper layer warm water is significantly longer than the residence time of the lower warm water. Therefore, when a predetermined time has elapsed since it was detected that the temperature of the hot water in the lower part of the hot water tank is lower than the sterilization temperature, the hot water in the upper layer has not passed the sterilization temperature and the predetermined time has passed. There is a possibility. In this case, the sterilization operation is performed later than the timing at which the sterilization operation should be performed. With the technique of Patent Document 1, it is difficult to use the hot water supply device in a sanitary manner.
An object of the present invention is to provide a hot water storage hot water supply system that can be used in a sanitary manner while sterilizing hot water in a hot water storage tank at an appropriate timing and suppressing waste of energy.

The hot water storage type hot water supply system of the present invention includes a hot water storage tank for storing hot water and heating means for heating the hot water stored in the hot water storage tank. This hot water storage type hot water supply system is distributed in a plurality of locations in the vertical direction in the hot water storage tank. The hot water tank temperature distribution detecting means for detecting the hot water temperature distribution in the hot water storage tank, and the hot water tank to the heating means. Sending hot water temperature detecting means for detecting the temperature of the hot water sent out, timing means for measuring the time when the hot water temperature detected by the sending hot water temperature detecting means is equal to or higher than a predetermined temperature, and detecting the flow rate of hot water supplied from the hot water tank And a hot water flow rate integration unit that integrates the flow rate detected by the hot water flow rate detection unit from the first predetermined time to the present time. Moreover, the prohibition means which prohibits the hot water supply from the hot water storage tank, and the sterilization means are provided. In the sterilizing means, the accumulated flow rate for the first predetermined time accumulated by the hot water flow rate integrating means is not more than the hot water tank capacity, and the detected temperature is not less than the predetermined temperature in the hot water tank temperature distribution detecting means. When the amount of hot water up to the water level where the lowest one is located is less than the hot water amount obtained by subtracting the integrated flow rate from the hot water tank capacity, the prohibiting means and heating means are operated and timed by the time measuring means When the time reaches the second predetermined time, the prohibition means is canceled,
The first predetermined time is a time that is slightly short of the time for the bacteria to start breeding in the hot water in the hot water tank, the first predetermined time is slightly longer than the time required for high temperature sterilization, and the predetermined time is high temperature sterilization. The temperature is slightly higher than the temperature required for.

There is hot water staying in the hot water tank for a long time (for example, 48 hours or more, which is the first predetermined time here), and the hot water temperature is a temperature at which bacteria can propagate. If there is, there is no possibility that harmful bacteria such as Legionella bacteria propagate in the warm water. In other words, even if the hot water temperature in the hot water tank is a temperature at which bacteria can propagate, if the hot water in the hot water tank is replaced, there is no need to remove the bacteria, and the hot water in the hot water tank Even if it is not replaced, it is not necessary to remove bacteria if the temperature of the hot water in the hot water tank is higher than the sterilization temperature.
In the present invention, the amount of hot water supplied from the hot water tank is integrated for a predetermined time (for example, 48 hours), and the integrated flow rate is compared with the hot water tank capacity. As a result, if the integrated flow rate is greater than or equal to the hot water storage tank capacity, it can be seen that the hot water in the hot water storage tank has been replaced within a predetermined time. There is hot water staying above, and you can see how much hot water is present. Moreover, in this invention, the temperature distribution detection means is disperse | distributed and arrange | positioned in the up-down direction in the hot water storage tank. The temperature distribution of the hot water in the hot water tank can be ascertained based on the detected temperature of the temperature distribution detecting means. According to these, when there is hot water staying in the hot water storage tank for a predetermined time or more, whether the staying hot water is equal to or higher than the sterilization temperature by comparing the amount of hot water remaining and the amount of hot water equal to or higher than the sterilization temperature. It can be determined whether or not. Of the hot water tank temperature distribution detection means, the hot water amount up to the water level where the lowest one of the detection temperatures is higher than the predetermined temperature is less than the hot water amount obtained by subtracting the integrated flow rate from the hot water tank capacity. At some point, it can be seen that a portion of the hot water staying in the hot water storage tank for a predetermined time or more has dropped below the sterilization temperature, requiring sterilization treatment. According to the present invention, since the heat sterilization can be performed only when a part of the hot water staying in the hot water tank for a predetermined time or less is below the sterilization temperature, the hot water in the hot water tank is sterilized at an appropriate timing. can do.
During the sterilization process, hot water supply in the hot water tank is prohibited, so that unsterilized hot water is not supplied and is hygienic.

  Another hot water storage type hot water supply system of the present invention is a hot water storage tank for storing hot water, and a hot water storage tank that is arranged in a plurality of locations in the vertical direction in the hot water storage tank and detects the temperature distribution of the hot water in the hot water storage tank. An internal temperature distribution detecting means, a hot water flow detecting means for detecting the flow of hot water supplied from the hot water tank, and a hot water flow integrating means for integrating the flow detected by the hot water flow detecting means from the first predetermined time to the present time; It has. In addition, a prohibition means for prohibiting hot water supply from the hot water tank, a replacement means for replacing the hot water in the hot water tank, a replacement flow rate detection means for detecting the flow rate of the water replaced by the replacement means, And means for controlling the switching means. Then, the control means is such that the accumulated flow for the first predetermined time accumulated by the hot water flow accumulation means is equal to or less than the hot water tank capacity, and the detected temperature is equal to or higher than the predetermined temperature in the hot water tank temperature distribution detection means. When the amount of hot water up to the water level where the lowest one is located is equal to or less than the hot water amount obtained by subtracting the accumulated flow rate from the hot water tank capacity, the prohibition unit and the replacement unit are operated and detected by the replacement flow rate detection unit The prohibiting means is canceled when the exchange flow rate to be reached reaches a predetermined flow rate. The predetermined flow rate is more than the hot water tank capacity.

  Also in the present invention, when there is hot water staying in the hot water tank for a predetermined time or more, it can be determined whether or not the staying hot water is higher than the sterilization temperature. In the present invention, the hot water tank is replaced at an appropriate timing by replacing the hot water in the hot water tank only when a part of the temperature of the hot water staying in the hot water tank is lower than the sterilization temperature. The hot water inside can be replaced with fresh tap water.

  In the hot water storage type hot water supply system of the present invention, the hot water in the hot water storage tank is sterilized or replaced only when there is hot water staying in the hot water storage tank for a predetermined time or more and a part of the hot water stays below the sterilization temperature. It can be performed. According to the hot water storage type hot water supply system of the present invention, there is no waste of energy by wasting sterilization or replacement of hot water in the hot water storage tank, and the timing is delayed, and an unsanitary state does not occur.

Hereinafter, preferred embodiments of the present invention will be described.
(Mode 1) The first predetermined time is slightly shorter than the time required for the number of bacteria breeding in the hot water tank to be a harmful number when the hot water in the hot water tank is maintained at a temperature at which bacteria can propagate. It is a short time.
(Mode 2) The sending hot water temperature detecting means is arranged in a path for sending the hot water in the hot water tank to the heating means.
(Mode 3) The hot water flow rate detecting means may be a flow meter for measuring the amount of hot water sent from the hot water tank to the mixing unit, or mixed with the temperature of the hot water sent from the hot water tank to the mixing unit. You may calculate from the temperature of mixed water, supply water temperature, and the flow rate of hot water supplied.
(Mode 4) The prohibiting means prohibits hot water from being supplied from the hot water tank by prohibiting the opening and closing valve provided in the middle of the hot water path connecting the hot water tank and the mixing unit.
(Embodiment 5) When equipped with a mixed water heating means for heating the mixed water from the mixing unit as required, and when the hot water is requested while the opening / closing valve of the hot water path is prohibited by the prohibiting means, The tap water from the mixing unit is heated by the mixed water heating means to supply hot water.
(Mode 6) The first predetermined temperature is slightly higher than the temperature effective for sterilization (sterilization temperature).
(Mode 7) The second predetermined time is slightly longer than the time required to complete the heat sterilization at the first predetermined temperature.
(Mode 8) The switching means for switching the hot water in the hot water tank includes an on-off valve provided in the hot water drainage path branched from the hot water path.
(Mode 9) The switching means control means opens the open / close valve of the hot water drainage path only when there is hot water staying in the hot water tank for a predetermined time or more and a part of the staying hot water is below the sterilization temperature. When the amount of discharged water reaches a predetermined flow rate, the on-off valve of the hot water drainage path is closed.
(Mode 10) The predetermined flow rate is the hot water storage tank capacity + α.

Example 1
A first embodiment of the hot water storage type hot water supply system of the present invention will be described with reference to the drawings. A present Example is a cogeneration system incorporating the hot water storage type hot-water supply system of this invention.
As shown in FIG. 1, the cogeneration system of the present embodiment includes a power generation unit 110, a hot water supply system 10, and the like.
The power generation unit 110 includes a reformer 112, a fuel cell 114, heat exchangers 116 and 118, a heat medium radiator 120, a heat medium three-way valve 122, a path connecting them, and the like.
The reformer 112 is provided with a burner 131. When the burner 131 is operated to generate heat, the reformer 112 generates hydrogen gas from hydrocarbon-based gas. The high-temperature combustion gas burned by the burner 131 is guided to the combustion gas path 126. The combustion gas path 126 passes through the heat exchanger 116 from the reformer 112 and is opened to the outside. A circulation path 128 also passes through the heat exchanger 116. The combustion gas path 126 guides the high-temperature combustion gas generated in the burner 131 to the heat exchanger 116, heats the water flowing through the circulation path 128, and discharges the combustion gas whose temperature has been lowered by heat exchange to the outside.
The circulation path 128 includes a circulation return path 128 a and a circulation outward path 128 b and is connected to the hot water supply system 10. How the circulation path 128 is connected to the hot water supply system 10 will be described in detail later. The circulation path 128 circulates hot water. The hot water flowing through the circulation path 128 is heated by the combustion gas flowing through the combustion gas path 126 by passing through the heat exchanger 116, and the temperature rises.

The fuel cell 114 is a solid polymer fuel cell and has a plurality of cells. The fuel cell 114 and the reformer 112 are connected by a hydrogen gas supply path 121. The hydrogen gas generated by the reformer 112 flows through the hydrogen gas supply path 121 and is supplied to the fuel cell 114. The fuel cell 114 generates power by reacting the hydrogen gas supplied from the reformer 112 with oxygen in the air. When the fuel cell 114 generates power, it generates heat.
The heat medium circulation path 124 forms a circulation path that returns to the fuel cell 114 through the fuel cell 114, the heat exchanger 118, the reserve tank 125, the heat medium pump 127, and the heat medium three-way valve 122. A heat medium temperature sensor 117 and a freezing prevention heater 123 are mounted on the downstream side of the fuel cell 114 in the heat medium circulation path 124. The heat medium temperature sensor 117 detects the temperature of the heat medium flowing through the heat medium circulation path 124. The detection signal of the heat medium temperature sensor 117 is output to the controller 21 attached to the hot water supply system 10. The antifreezing heater 123 is an electric heater that heats the heat medium circulation path 124.
The heat medium three-way valve 122 includes one inlet 122a and two outlets 122b and 122c. The heat medium three-way valve 122 switches between communication between the inlet 122a and the outlet 122b or communication between the inlet 122a and the outlet 122c.
A cooling path 129 that connects the outlet 122b of the heat medium three-way valve 122 and the downstream side of the outlet 122c of the heat medium three-way valve 122 of the heat medium circulation path 124 is provided. The heat medium circulation path 124 and the cooling path 129 circulate pure water as a heat medium. A heat medium radiator 120 is mounted in the middle of the cooling path 129. A heat medium cooling fan 119 is provided adjacent to the heat medium radiator 120. When the heat medium cooling fan 119 is operated, air is blown to the heat medium radiator 120, and the heat medium flowing through the cooling path 129 is cooled.
The controller 21 controls the reformer 112, the fuel cell 114, the burner 131, the heat medium pump 127, the antifreezing heater 123, the heat medium three-way valve 122, and the heat medium cooling fan 119.

When the fuel cell 114 is activated, the inlet 122a and the outlet 122c of the heat medium three-way valve 122 are communicated and the heat medium pump 127 is operated. When the heat medium pump 127 is operated, the heat medium circulates through the heat medium circulation path 124. The heat generation medium is recovered from the fuel cell 114 by circulating the heat medium through the heat medium circulation path 124. The generated heat recovered by the heat medium is transported together with the heat medium to the heat exchanger 118 and heats the hot water flowing through the circulation path 128. The circulation path 128 will be described later.
If the temperature of the heat medium detected by the heat medium temperature sensor 117 becomes too high, the generated heat is not sufficiently recovered, and thus the generated heat is dissipated. The inlet 122a and outlet 122b of the heat medium three-way valve 122 are communicated with each other, and the heat medium cooling fan 119 is operated at the same time. When the inlet 122 a and the outlet 122 b of the heat medium three-way valve 122 communicate with each other, the heat medium flows into the cooling path 129 and passes through the heat medium radiator 120. The heat medium is cooled by passing through the heat medium radiator 120. The heat medium radiator 120 radiates heat with high efficiency when air is blown from the heat medium cooling fan 119. When the temperature of the heat medium decreases, the inlet 122a and the outlet 122c of the heat medium three-way valve 122 are communicated again. By repeating such switching of the heat medium three-way valve 122, the temperature of the heat medium is maintained within a predetermined range.

The hot water supply system 10 includes a hot water tank 20, a hot water heater (heater) 22, a mixing unit (mixer) 24, a plurality of paths that connect these, a controller 21, and the like.
A water supply path 26 for supplying tap water to the hot water tank 20 is connected to the bottom of the hot water tank 20. In the vicinity of the inlet 26 a of the water supply path 26, a pressure reducing valve 28 is attached. The downstream side of the pressure reducing valve 28 in the water supply path 26 and the water supply inlet 24 a of the mixing unit 24 are connected by a mixing unit water supply path 30. The pressure reducing valve 28 adjusts the water supply pressure to the hot water tank 20 and the mixing unit 24. When the hot water in the hot water storage tank 20 decreases or the water supply inlet 24a of the mixing unit 24 opens, the downstream pressure of the pressure reducing valve 28 decreases. The pressure reducing valve 28 opens when the downstream pressure decreases, and tries to maintain the pressure at a predetermined pressure regulation value. For this reason, when the hot water in the hot water storage tank 20 decreases or the water supply inlet 24a of the mixing unit 24 opens, tap water is supplied to them.
The hot water storage tank 20 stores water regulated to a regulated pressure value. The hot water tank 20 is formed of a pressure resistant container that can withstand the pressure regulation value. An outlet 20a is provided at the upper part of the hot water tank 20, and a relief valve 31 is mounted thereon. The valve opening pressure of the relief valve 31 is set slightly higher than the pressure regulation value of the pressure reducing valve 28. When the pressure regulation of the pressure reducing valve 28 becomes impossible, the relief valve 31 is opened to prevent the pressure in the hot water tank 20 from exceeding the pressure resistance. One end 32 a of a pressure release path 32 is connected to the relief valve 31. The other end 32 b of the pressure release path 32 is open to the outside of the hot water tank 20.
A drainage path 33 that connects the bottom of the hot water tank 20 and the vicinity of the other end 32 b of the pressure release path 32 is provided. A drain valve 34 is attached in the middle of the drain path 33. The drain valve 34 can be manually opened and closed. When the drain valve 34 is opened, the water in the hot water tank 20 is drained to the outside through the drain path 33 and the open path 32.

The hot water tank 20 is connected to the circulation path 128 (circulation return path 128a, circulation forward path 128b) of the power generation unit 110. Specifically, the circulation return path 128 a is connected to the upper part of the hot water tank 20, and the circulation forward path 128 b is connected to the lower part of the hot water tank 20. Thereby, a circulation path between the hot water tank 20 and the power generation unit 110 is formed. A circulation pump 40 is mounted in the middle of the circulation outward path 128b. A return thermistor 45 is attached to the circulation return path 128a, and an outward thermistor 44 is attached to the circulation outward path 128b. The return thermistor 45 detects the temperature of hot water in the circulation return path 128a, and the outward thermistor 44 detects the temperature of hot water in the circulation return path 128b. Detection signals from the return thermistor 45 and the outward thermistor 44 are output to the controller 21.
When the circulation pump 40 is activated during the power generation operation, hot water is sucked from the bottom of the hot water tank 20. The hot water sucked from the hot water storage tank 20 is heated by passing through the heat exchangers 118 and 116 of the power generation unit 110 after flowing through the circulation outward path 128b, and the temperature rises. The hot water whose temperature has risen flows through the circulation return path 128 a and is returned to the upper part of the hot water tank 20. In this way, the hot water sucked out from the bottom of the hot water tank 20 is heated by the heat exchangers 118 and 116 of the power generation unit 110 to become higher temperature, and the circulation returning to the upper part of the hot water tank 20 is performed. Hot water is stored in the hot water tank 20. When the hot water from the power generation unit 110 is returned to the hot water tank 20 from the state where the temperature in the hot water tank 20 is low, the hot water is returned to the upper part of the hot water tank 20, so that the high temperature layer is formed above the cold water layer. Is formed (hereinafter referred to as “temperature stratification”). The temperature of water deeper than the high temperature layer drops rapidly. During power generation, when the low temperature hot water is sucked out from the bottom of the hot water tank 20 and the high temperature hot water continues to be returned to the top, the high temperature layer does not cross with the low temperature layer, and the thickness (depth) of the low temperature layer gradually increases. It becomes smaller and the thickness (depth) of the high temperature layer becomes gradually larger. In a state where the hot water storage tank 20 is fully stored, high temperature hot water is stored in the entire hot water storage tank 20. By forming the temperature stratification, high-temperature hot water is sent out from the outlet 20a provided at the uppermost part of the hot water tank 20, even if the hot water tank 20 is not fully heat-accumulated. On the other hand, when hot water in the hot water tank 20 is used, hot hot water at the top of the hot water tank 20 is sucked out, and when tap water enters from the bottom, the thickness (depth) of the high temperature layer gradually decreases, and the low temperature layer The thickness (depth) of the film gradually increases. When the hot water in the hot water tank 20 is used up, the hot water tank 20 is filled with tap water.

  The controller 21 includes a CPU, a ROM, a RAM, and the like, and the power generation unit 110 and the hot water supply system 10 are controlled by the CPU processing a control program stored in the ROM. The RAM temporarily stores various signals input to the controller 21 and various data generated in the course of execution of processing by the CPU. A remote controller 23 is connected to the controller 21. The remote controller 23 is provided with switches and buttons for operating the power generation unit 110 and the hot water supply system 10, a liquid crystal display for displaying the operation state of the power generation unit 110 and the hot water supply system 10 and displaying an operation method described later. Yes.

  In the hot water tank 20, four hot water tank thermistors 35a, 35b, 35c, and 35d are attached. The hot water tank thermistor A35a is attached at a location of 5 liters from the upper part of the hot water tank 20, and the hot water tank thermistor B35b is attached at a location of 40 liters from the hot water tank thermistor A35a (45 liters from the upper part). The hot water tank thermistor C35c is mounted at a location 40 liters from the hot water reservoir thermistor B35b (85 liters from the top), and the hot water tank thermistor D35d is 40 liters from the hot water tank thermistor C35c (125 liters from the top). Installed). The detection signals from the four hot water tank thermistors 35a, 35b, 35c, and 35d are output to the controller 21, respectively. The detected temperatures of the four hot water tank thermistors 35a, 35b, 35c, and 35d are used for hot water temperature control and for calculation of the heat storage amount. The calculated heat storage amount is stored over time in a storage unit prepared in the controller 21.

  The mixing unit 24 includes a hot water inlet 24c, a mixed water outlet 24b, a first flow rate sensor 67, a hot water thermistor 50, a water supply thermistor 48, a mixed water thermistor 54, a high-cut thermistor 55, and the water supply inlet 24a already described. The outlet 20 a of the hot water tank 20 and the hot water inlet 24 c of the mixing unit 24 are connected by a hot water path 42. The warm water path 42 is provided with a warm water flow rate sensor 46 and a warm water path opening / closing valve 43. A hot water drainage path 41 is branched from the middle of the hot water path 42. The hot water drainage path 41 is provided with a hot water drainage path opening / closing valve 49. When the hot water drainage path opening / closing valve 49 is opened, tap water is sent from the water supply path 26 to the hot water storage tank 20 and is pushed out therefrom, so that the hot water from the hot water storage tank 20 is drained outside the hot water supply system 10. While the hot water drainage path opening / closing valve 49 is opened, the hot water path opening / closing valve 43 is closed. The hot water flow rate sensor 46 detects the flow rate of hot water delivered from the hot water storage tank 20. The first flow sensor 67 detects the flow rate of the mixed water flowing out from the mixed water outlet 24b. The hot water thermistor 50 detects the temperature of the hot water flowing into the hot water inlet 24c. The water supply thermistor 48 detects the temperature of the tap water flowing into the water supply inlet 24a. The mixed water thermistor 54 and the high cut thermistor 55 detect the temperature of the mixed water flowing out from the mixed water outlet 24b. Detection signals of the hot water flow sensor 46, the hot water path on / off valve 43, the hot water drain path on / off valve 49, the first flow sensor 67, the hot water thermistor 50, the feed water thermistor 48, the mixed water thermistor 54, and the high cut thermistor 55 are output to the controller 21. .

The controller 21 uses the detection signal of the mixed water thermistor 54 to change the opening on the hot water inlet 24c side and the opening on the water supply inlet 24a side. While the hot water inlet 24c is open, the hot water path opening / closing valve 43 is also opened. While the hot water inlet 24c is closed, the hot water path opening / closing valve 43 is also closed. When the opening degree on the hot water inlet 24c side and the opening degree on the water supply inlet 24a side are changed, the mixing ratio between the hot water from the hot water storage tank 20 and tap water (cold water) is adjusted. When the mixing ratio between the hot water from the hot water tank 20 and the tap water is adjusted, the temperature of the hot water flowing out from the mixed water outlet 24b is maintained at a predetermined value. By using the controller 21 and the mixing unit 24 in combination, the temperature of the mixed water measured by the mixed water thermistor 54 is adjusted to the temperature commanded by the controller 21.
When it is detected by the high-cut thermistor 55 that the hot water has greatly exceeded the predetermined value (that is, when there is a high possibility that the mixed water thermistor 54 or the mixing unit 24 has failed), the controller 21 opens the hot water inlet 24c. close. When the hot water inlet 24c is closed, the hot water having a temperature that greatly exceeds the predetermined value is prevented from being supplied to the water heater 22.
A mixed water outlet 24 b of the mixing unit 24 and a burner heat exchanger 52 (described later) of the water heater 22 are connected by a mixed water path 51. A second flow rate sensor 47 is attached to the mixed water path 51. A detection signal from the second flow sensor 47 is output to the controller 21.

The water heater 22 includes burner heat exchangers 52 and 60, burners 56 and 57, a reheating heat exchanger 58, a replenishing water valve 59, a cistern 61, and the like. Hot water flows from the mixing unit 24 into the burner heat exchanger 52 via the mixed water path 51. The gas combustion type burner 56 heats the burner heat exchanger 52. When the burner 56 receives an ignition instruction from the controller 21, it starts combustion after performing a pre-purge operation. The time required for the pre-purge is set based on the size and rotational speed of the combustion fan, the capacity of the portion where the combustion gas of the burners 56 and 57 passes through the burner heat exchangers 52 and 60, and is exhausted to the outside of the apparatus. 21 is stored. The pre-purge usually takes several seconds. In the burner 56 of this embodiment, the time for the pre-purge is 1.5 seconds.
The downstream side of the burner heat exchanger 52 and the hot water tap 64 are connected by a hot water tap path 63. The hot-water tap 64 is arranged in a bathroom, a washroom, a kitchen, etc. (in FIG. 1, the plurality of hot-water taps 64 are represented by one). A hot water supply thermistor 65 is attached to the hot water supply passage 63. The hot water supply thermistor 65 detects the temperature of hot water flowing out of the burner heat exchanger 52. A detection signal from the hot water supply thermistor 65 is output to the controller 21.

  A bypass pipe 37 that bypasses the burner heat exchanger 52 is formed in the mixed water path 51. The bypass pipe 37 is provided with a bypass servo 38. The opening degree of the bypass servo 38 is controlled by the controller 21, and the opening degree is adjusted by driving a built-in stepping motor. When the bypass servo 38 is opened, there is a bypass path that branches from the upstream side of the burner heat exchanger 52 in the mixed water path 51, passes through the bypass pipe 37, and joins the downstream side of the burner heat exchanger 52 in the mixed water path 51. It is formed. By controlling the opening degree of the bypass servo 38 by the controller 21, the bypass ratio that is the ratio of the flow rate to the bypass pipe 37 with respect to the flow rate to the burner heat exchanger 52 is controlled.

From the middle of the mixed water path 51 in the water heater 22, a systern water inlet path 62 is branched. The open end of the cistern water intake path 62 is inserted into the upper part of the cistern 61. A makeup water valve 59 is provided in the middle of the cistern water intake path 62. The makeup water valve 59 is controlled by the controller 21 and opens and closes when a built-in solenoid is driven. When the replenishing water valve 59 is opened, hot water from the mixing unit 24 is supplied to the cistern 61.
A water level electrode 66 is mounted in the cis turn 61. The water level electrode 66 has a rod-shaped high level switch 66a and a low level switch 66b. The lower end of the high level switch 66 a is located at the high level water level of the cistern 61. The lower end of the low level switch 66 b is located at the low level water level of the cistern 61. The high level switch 66a and the low level switch 66b output a detection signal to the controller 21 when they are in contact with water. Based on the detection signal from the water level electrode 66, the controller 21 determines whether the water level of the cistern 61 exceeds the high level water level, is between the high level water level and the low level water level, or is lower than the low level water level. What is appropriate as the cis turn 61 is a state where the water level is located between the high level and the low level. The controller 21 controls opening / closing of the replenishing water valve 59 based on the water level detection signal from the water level electrode 66 and maintains the water level of the cistern 61 within an appropriate range.

One end of a cistern water discharge path 68 is connected to the bottom of the cistern 61. A heating pump 69 is mounted in the middle of the cistern water discharge path 68. The heating pump 69 is controlled by the controller 21. The other end of the cistern water discharge path 68 branches into a burner upstream path 71 and a low-temperature water path 70. The burner upstream path 71 connects the cistern water discharge path 68 and the upstream side of the burner heat exchanger 60. A heating low temperature thermistor 72 that detects the temperature of the hot water flowing inside is installed in the burner upstream path 71. A detection signal of the heating low temperature thermistor 72 is output to the controller 21.
The gas combustion type burner 57 heats the burner heat exchanger 60. The downstream of the burner heat exchanger 60 and the cistern 61 are connected by a high-temperature water path 73. A heating high temperature thermistor 74, a heating terminal thermal valve 75, and a heating terminal 76 are attached to the high temperature water path 73 in order from the upstream side.
The heating high temperature thermistor 74 detects the temperature of the hot water flowing through the high temperature water path 73. A detection signal of the heating high temperature thermistor 74 is output to the controller 21.

The heating terminal 76 includes a heat exchanger 76b, an operation switch 76a, and an electric fan (not shown). The heat exchanger 76 b performs heat exchange between the hot water flowing through the high temperature water path 73 and the air. The operation switch 76 a is connected to the heating terminal thermal valve 75 and the controller 21.
The heating terminal thermal valve 75 includes an expansion element and an on-off valve mechanically connected to the expansion element. When the operation switch 76a of the heating terminal 76 is turned on, power is supplied to the expansion element of the heating terminal thermal valve 75. The energized expansion element becomes hot and expands. The expanded expansion element drives the on-off valve, thereby opening the heating terminal thermal valve 75. Further, when the operation switch 76 a is turned on, the controller 21 operates the heating pump 69. As described above, when the operation switch 76a is turned on, the heating terminal thermal valve 75 is opened, and when the heating pump 69 is activated, hot water is sucked from the cistern 61. The controller 21 controls the burner 57 based on the hot water temperature detected by the heating low temperature thermistor 72 and the heating high temperature thermistor 74, and maintains the temperature of the hot water flowing out of the burner heat exchanger 60 within a predetermined range. The electric fan of the heating terminal 76 rotates when the operation switch 76a is turned on, and blows air to the heat exchanger 76b. The air blown to the heat exchanger 76b is warmed by exchanging heat with warm water via the heat exchanger 76b. Warmed air blows out from the heating terminal 76 to heat the room. By performing heat exchange with air in the heat exchanger 76b, the temperature of the hot water decreases. The warm water whose temperature has decreased flows through the high-temperature water path 73 and returns to the cistern 61.

The downstream side of the heating high temperature thermistor 74 in the high temperature water path 73 and the upstream side of the entrance to the cistern 61 in the high temperature water path 73 are connected by a tracking path 77. The tracking path 77 passes through the tracking heat exchanger 58. On the upstream side of the tracking heat exchanger 58 in the tracking path 77, a tracking thermal valve 78 is mounted. The reheating heat valve 78 is controlled by the controller 21.
The bathtub 79 is provided with a suction port 79a and a supply port 79b. The suction port 79 a and the supply port 79 b are connected by a bath circulation path 80. The bath circulation path 80 passes through the reheating heat exchanger 58. As described above, the tracking path 77 also passes through the tracking heat exchanger 58. For this reason, in the reheating heat exchanger 58, heat exchange is performed between the bath circulation path 80 and the reheating path 77. A bath water level sensor 81, a bath circulation pump 82, and a bath water flow switch 84 are mounted on the upstream side of the reheating heat exchanger 58 in the bath circulation path 80. The bath circulation pump 82 is controlled by the controller 21. The bath water level sensor 81 and the bath water flow switch 84 output detection signals to the controller 21. The bath water level sensor 81 detects water pressure. The controller 21 estimates the water level of the hot water stretched on the bathtub 79 from the water pressure detected by the bath water level sensor 81. The bath water flow switch 84 is turned on when water flows through the bath circulation path 80.
On the upstream side of the bath water level sensor 81 in the bath circulation path 80, a bath thermistor 85 that detects the temperature of hot water sucked out from the bathtub 79 is mounted. The detection signal of the bath thermistor 85 is output to the controller 21.

  When the reheating heat valve 78 is opened while the burner 57 and the heating pump 69 are operating, the hot water flows into the reheating path 77 and passes through the reheating heat exchanger 58. When the bath circulation pump 82 is activated, the hot water is sucked out from the suction port 79a of the bathtub 79, flows through the bath circulation path 80, and returns to the bathtub 79 from the supply port 79b again. The hot water flowing through the bath circulation path 80 is heated by the hot water flowing through the chasing path 77 by the chasing heat exchanger 58 and the hot water in the bathtub 79 is chased.

A hot water filling path 25 that connects the middle of the hot-water tap path 63 and the downstream side of the bath circulation pump 82 of the bath circulation path 80 is provided. A solenoid drive type pouring valve 27 and a hot water filling amount sensor 83 are attached to the hot water filling passage 25. The pouring valve 27 is controlled by the controller 21 and opens and closes the hot water filling path 25. The hot water filling amount sensor 83 detects the amount of water flowing through the hot water filling passage 25 to estimate how much the hot water filling operation has been performed to the bathtub 79. The hot water filling amount sensor 83 outputs a detection signal to the controller 21.
When hot water is filled in the bathtub 79, the hot water pouring valve 27 is opened. When the pouring valve 27 is opened, hot water flows from the hot water tap path 63 through the hot water filling path 25 into the bath circulation path 80. Hot water that has flowed into the bath circulation path 80 is supplied to the bathtub 79 from the suction port 79 a and the supply port 79 b, and is filled in the bathtub 79. At this time, the bath circulation pump 82 is not driven, and the water filling operation to the bathtub 79 is performed by the water pressure applied to the water filling passage 25.

In the middle of the low-temperature water path 70, a low-temperature thermistor 94, a floor heating thermal valve 90, and a floor heater 91 are provided. The floor heater 91 warms the floor with warm water flowing through the low-temperature water path 70. When performing floor heating, the floor heating thermal valve 90 is opened, and the hot water is guided to the floor heater 91. The guided hot water warms the floor heater 91. When floor heating is not performed, the floor heating thermal valve 90 is closed. The low temperature thermistor 94 detects the temperature of the hot water flowing through the low temperature water path 70. The detection signal of the low temperature thermistor 94 is output to the controller 21. The floor heating thermal valve 90 is controlled by the controller 21.
The upstream side of the heating terminal thermal valve 75 in the high temperature water path 73 and the downstream side of the floor heater 91 in the low temperature water path 70 are connected by a bypass path 92. When the heating pump 69 is operated with the heating terminal thermal valve 75 and the floor heating thermal valve 90 closed, the hot water in the cistern 61 is sequentially turned to the burner upstream path 71, the burner heat exchanger 60, the high-temperature water path 73, A bypass path 92, a low-temperature water path 70, and a high-temperature water path 73 flow to form a path back to the cistern 61.

In the cogeneration system of the present embodiment, when there is hot water that has not been used for a long time in the hot water tank 20, bacteria that adversely affect the human body such as Legionella bacteria may be propagated in the hot water. The stored water is sterilized by the procedure shown in 2.
As shown in FIG. 2, when the system power is turned on in step S10 (YES), the process proceeds to step S12. In step S12, the time measurement by the timer is started and the integration of the flow rate detected by the hot water flow rate sensor 46 is started. The hot water flow rate sensor 46 is provided in a hot water path 42 that connects the hot water storage tank 20 and the mixing unit 24, and detects the flow rate of the hot water sent out from the hot water storage tank 20.
In the normal operation of step S14, when the hot water temperature in the hot water tank 20 is equal to or higher than the hot water supply set temperature, the mixing unit 24 adjusts the hot water and tap water from the hot water tank 20 to the hot water set temperature to supply hot water. When the hot water temperature in the hot water tank 20 is lower than the hot water supply set temperature, the hot water is heated to the hot water set temperature by the burner 56 to supply hot water. When the hot water temperature in the hot water storage tank 20 is slightly lower than the hot water supply set temperature, but when this hot water is heated with the minimum heating amount of the burner 56, the hot water temperature exceeds the hot water supply set temperature, and when the hot water is heated with the minimum heating amount of the burner 56 In the mixing unit 24, the temperature is lowered in advance so that the hot water can be supplied at the hot water set temperature so that the hot water set temperature is reached.

  In step S16, it is determined whether or not the integrated flow rate from 48 hours ago to the present time (this is x liters) is 150 liters or less, which is the hot water storage tank capacity. If the integrated flow rate x exceeds 150 liters (if NO), the hot water in the hot water tank 20 has been replaced at least once within 48 hours, so bacteria in the hot water in the hot water tank 20 May be considered not to be breeding. Accordingly, the process proceeds to step S22, and after 1 hour has elapsed (when it becomes YES), the process returns to the normal operation of step S14 and the above processing is repeated. Thereby, it is monitored whether or not the integrated flow rate from 48 hours before exceeds the hot water storage tank capacity every hour.

If the integrated flow rate x is 150 liters or less in step S16 (if YES), the hot water in the hot water storage tank 20 has not been changed even once within 48 hours, and more time has passed. Then, there will be hot water staying in the hot water tank 20 for more than 48 hours. Thus, there is no possibility that bacteria will propagate in the hot water that stays in the hot water tank 20 for a long time. However, if the temperature of the hot water staying in the hot water tank 20 for a long time is 60 ° C. or higher, there is no need to worry about the growth of bacteria. Therefore, it progresses to step S18 and grasps | ascertains the amount of hot water of 60 degreeC or more (this is set as y liter) among the hot water in the hot water storage tank 20. FIG. Specifically, the process of step S18 is performed as follows.
First, it is determined whether or not the detected temperature of the hot water tank thermistor D35d is 60 ° C. or higher. If the detected temperature of the hot water tank thermistor D35d is 60 ° C. or higher, the hot water temperature for 125 liters from the position where the hot water tank thermistor D35d is attached, that is, from the upper part of the hot water tank 20, is 60 ° C. or higher. Can be considered. At this time, [y = 125 (liters)].
When the detected temperature of the hot water tank thermistor D35d is less than 60 ° C., it is determined whether or not the detected temperature of the hot water tank thermistor C35c is 60 ° C. or higher. If the detected temperature of the hot water tank thermistor D35d is less than 60 ° C. and the detected temperature of the hot water tank thermistor C35c is 60 ° C. or higher, it is above the position where the hot water tank thermistor C35c is attached, that is, above the hot water tank 20. It can be considered that the hot water temperature for 85 liters is 60 ° C. or higher. At this time, [y = 85 (liter)].
When the detected temperature of the hot water tank thermistor C35c is less than 60 ° C, it is determined whether or not the detected temperature of the hot water tank thermistor B35b is 60 ° C or higher. If the detected temperature of the hot water tank thermistor C35c is less than 60 ° C. and the detected temperature of the hot water tank thermistor B35b is 60 ° C. or more, it is above the position where the hot water tank thermistor B35b is attached, that is, above the hot water tank 20. It can be considered that the hot water temperature for 45 liters is 60 ° C. or higher. At this time, [y = 45 (liters)].
When the detected temperature of the hot water tank thermistor B35b is lower than 60 ° C., it is determined whether or not the detected temperature of the hot water tank thermistor A 35a is 60 ° C. or higher. If the detected temperature of the hot water tank thermistor B35b is less than 60 ° C. and the detected temperature of the hot water tank thermistor A 35a is 60 ° C. or higher, the upper part of the hot water tank thermistor A 35a is attached, that is, the upper part of the hot water tank 20. Therefore, it can be considered that the temperature of hot water for 5 liters is 60 ° C. or more. At this time, [y = 5 (liter)].

  In step S20, the amount of hot water (retained hot water) that has been retained in the hot water tank for more than 48 hours (150-x (liter)) is the amount of hot water (y liters) in the hot water tank 20 that is 60 ° C. or higher. It is determined whether or not it is above. If the amount of staying hot water (150-x) is less than the amount of hot water of 60 ° C. or more (if NO in step S20), all the staying hot water will be 60 ° C. or more. It can be assumed that there is no risk of bacterial growth. Accordingly, the process proceeds to step S22, and after 1 hour has elapsed (when it becomes YES), the process returns to the normal operation of step S14, the above processing is repeated, and the integrated flow rate from 48 hours before every hour exceeds the hot water storage tank capacity. Monitor whether or not

  If the amount of retained hot water [150-x (liters)] is greater than or equal to the amount of hot water (y liters) of 60 ° C. or higher in hot water tank 20 (if YES) in step S20, a portion of the retained warm water is 60. Since the temperature is lower than ° C., it is necessary to be concerned that bacteria will propagate in this low-temperature water when more time passes. Therefore, the heat sterilization process after step S24 is executed.

  In the heat sterilization process, in order to prevent the hot water before the sterilization process in the hot water tank 20 from being supplied, first, in step S24, the hot water path opening / closing valve 43 is kept closed. Thus, even if there is a hot water supply request while the hot water path opening / closing valve 43 is kept closed, the hot water in the hot water storage tank 20 during the sterilization process is not used for hot water supply. When there is a hot water supply request while the hot water path opening / closing valve 43 is closed, the tap water is heated to the hot water supply set temperature by the burner 56 of the hot water heater 22 to supply hot water.

In step S26, it is determined whether or not the power generation unit 110 is in a power generation operation. If the power generation operation is in progress (YES in step S26), the power generation heat recovery operation is executed, and low-temperature water is sent from the lower part of the hot water tank 20 to the power generation unit 110 and heated by the power generation heat in the power generation unit 110. The heated water is returned to the upper part of the hot water tank 20, so that the temperature of the hot water in the hot water tank 20 gradually increases from the upper part. If the power generation operation is not being performed in step S26 (if NO), the process proceeds to step S28 to forcibly start the power generation operation in order to heat the hot water in the hot water tank 20 with the generated heat.
In step S30, the hot water in the hot water storage tank 20 is sterilized by heating with the generated heat until the temperature detected by the forward thermistor 44 provided in the circulation outward path 128b of the circulation path 128 becomes 60 ° C. or higher (until YES). The hot water in the hot water tank 20 is sent from below to the power generation unit 110, heated by the generated heat, and returned to the upper part of the hot water tank 20. The detected temperature of the forward thermistor 44 being 60 ° C. or higher means that the hot water fed from the hot water tank 20 is 60 ° C. or higher, that is, the hot water temperature in the entire hot water tank 20 reaches 60 ° C. or higher. It will be done.

  It has been found that harmful bacteria such as Legionella can be killed by heating at 60 ° C. for about 5 minutes. Proceeding to step S32, timing by the timer is started and the state where the detected temperature of the forward thermistor 44 is 60 ° C. or higher is maintained. If the timer measurement time is 1 hour or longer in step S34 (if YES), the hot water in the entire hot water tank 20 is heated at 60 ° C. or higher for 1 hour. Thereby, it can be considered that the warm water in the entire hot water tank 20 is sufficiently heated and the sterilization treatment is completed. If the sterilization process is completed, the hot water in the hot water tank 20 can be used. Therefore, it progresses to step S36, the closed state of the hot water path | route opening-and-closing valve 43 maintained from step S24 is cancelled | released, and hot water can be supplied using the hot water in the hot water storage tank 20 in which the sterilization process was completed. Proceeding to step S38, the processing from step S14 to step S38 is repeated until the system power is turned off (YES). If the system power is turned off (YES in step S38), the process is terminated.

If hot water stays in the hot water tank for a long time (for example, 48 hours or more), and the hot water temperature is a temperature at which bacteria can propagate, harmful water such as Legionella bacteria can be added to the hot water. There is no possibility that bacteria will breed. In other words, even if the hot water temperature in the hot water tank is a temperature at which bacteria can propagate, if the hot water in the hot water tank is replaced, there is no need to remove the bacteria, and the hot water in the hot water tank Even if it is not replaced, it is not necessary to remove bacteria if the temperature of the hot water in the hot water tank is higher than the sterilization temperature.
In this embodiment, the amount of hot water sent from the hot water tank 20 to the mixing unit 24 is integrated for 48 hours, and this integrated flow rate (x liter) is compared with the hot water tank capacity (150 liters). As a result, if the integrated flow rate is equal to or greater than the hot water tank capacity, it can be seen that the hot water in the hot water tank 20 is replaced within 48 hours. If the integrated flow rate does not satisfy the hot water tank capacity, the hot water is stored in the hot water tank 20. It can be seen that there is warm water staying for more than 48 hours, and the amount of staying hot water [150-x (liter)] is also known. In this embodiment, four hot water tank thermistors 35a, 35b, 35c, and 35d are arranged in the hot water tank 20 so as to be dispersed in the vertical direction. Based on these detected temperatures, the temperature distribution of the hot water in the hot water tank 20 can be grasped. According to these, when there is hot water staying in the hot water storage tank 20 for 48 hours or more, the amount of staying hot water [150-x (liter)] is compared with the amount of hot water that is higher than the sterilization temperature (60 ° C.). By doing this, it is possible to determine whether the staying hot water is equal to or higher than the sterilization temperature. At this time, among the hot water tank thermistors 35a, 35b, 35c, and 35d, the amount of hot water up to the water level where the lowest one of the detected temperatures is equal to or higher than the sterilization temperature is equal to or higher than the sterilization temperature. (Y liter). Even if the staying hot water exists, there is no problem as long as the temperature of the staying hot water is equal to or higher than the sterilization temperature. Therefore, only when a part of the hot water temperature that has stayed in the hot water tank 20 for 48 hours or less is lower than the sterilization temperature, the power generation operation is performed and the heat sterilization by the generated heat is performed. During the sterilization process, the hot water in the hot water storage tank 20 is prohibited from being sent to the mixing unit 24 by maintaining the closed state of the hot water path opening / closing valve 43, so that unsterilized hot water is not supplied with hot water. . According to the present embodiment, since the hot water in the hot water tank 20 can be sterilized by heating at an appropriate timing, the hot water in the hot water tank 20 is sterilized to waste energy, or the timing is delayed. There is no hygienic condition.

(Example 2)
A second embodiment of the hot water storage type hot water supply system of the present invention will be described with reference to the drawings. This embodiment is also a cogeneration system incorporating the hot water storage type hot water supply system of the present invention. The configuration of the cogeneration system of this embodiment is the same as that of the cogeneration system of the first embodiment described in detail with reference to FIG. In the first embodiment, when there is hot water that has not been used for a long time in the hot water tank, bacteria that adversely affect the human body such as Legionella bacteria may be propagated, but sterilization treatment by heating is performed. In this embodiment, the hot water in the hot water tank is replaced instead. Therefore, here, the replacement process of the stored water will be mainly described, and the detailed description will be omitted for the rest. In this embodiment, the reference numerals used in the first embodiment are used as they are.

In the cogeneration system of the present embodiment, when hot water that has not been used for a long time exists in the hot water storage tank 20, the stored water is replaced by the procedure shown in FIG.
As shown in FIG. 3, the process from step S50 to step S64 is the same as the process from step S10 to step S24 of the first embodiment, and the outline is as follows. If it is determined that there is hot water that has not been used in the hot water tank 20 for a long time, it is determined that it is necessary to replace the hot water, and the hot water in the hot water tank 20 in which bacteria may have propagated is not supplied. In order to do so, the hot water path opening / closing valve 43 is kept closed. Even if there is a hot water supply request while the hot water path opening / closing valve 43 is kept closed, the hot water in the hot water storage tank 20 where bacteria may have propagated is not used for hot water supply. When there is a hot water supply request while the hot water path opening / closing valve 43 is closed, the tap water is heated to the hot water supply set temperature by the burner 56 of the hot water heater 22 to supply hot water.

  In step S66, the hot water drainage path opening / closing valve 49 provided in the hot water drainage path 41 is opened. As a result, the hot water in the upper part of the hot water tank 20 is drained from the end of the hot water drain path 41. At the same time, tap water is introduced from the lower part of the hot water tank 20. When the hot water drainage path opening / closing valve 49 is opened, the process proceeds to step S68, and integration of the flow rate detected by the hot water flow rate sensor 46 provided in the hot water path 42 is started. The flow rate integrated here is the amount of drainage. Proceeding to step S70, the hot water drainage path opening / closing valve 49 is opened and the hot water in the hot water tank 20 is drained until the amount of drainage becomes equal to or greater than the capacity of the hot water tank 20 (150 liters) + α (10 liters). Drain. α is a value larger than the piping capacity of the hot water passage 42. Thereby, the hot water in the hot water tank 20 is replaced with fresh water. Then, it progresses to step S72 and the warm water drainage path on-off valve 49 is closed. And it progresses to step S74, the closed state of the warm water path | route on-off valve 43 maintained from step S64 is cancelled | released, and hot water can be supplied using the warm water in the hot water storage tank 20 which the sterilization process was completed. Proceeding to step S76, the processing from step S54 to step S76 is repeated until the system power supply is turned off (YES). If the system power is turned off (YES in step S76), the process ends.

  Also in the present embodiment, as in the first embodiment, when there is hot water staying in the hot water tank 20 for 48 hours or more, it is determined whether or not the staying hot water is equal to or higher than the sterilization temperature (60 ° C.). be able to. In this embodiment, the hot water drain passage opening / closing valve 49 that opens and closes the hot water drain passage 41 that branches from the hot water passage 42 that connects the hot water tank 20 and the mixing unit 24 is controlled to open and close the hot water in the hot water bath 20. Can be replaced with tap water. Therefore, the hot water in the hot water tank 20 is replaced only when a part of the hot water temperature that has stayed in the hot water tank 20 for 48 hours or more is lower than the sterilization temperature. During the hot water replacement process, the hot water in the hot water storage tank 20 is prohibited from being sent out to the mixing unit 24 by maintaining the closed state of the hot water path opening / closing valve 43, so hot water that may be unsanitary. Will never get hot water. According to the present embodiment, since hot water in the hot water tank 20 can be replaced with fresh tap water at an appropriate timing, replacement of the hot water in the hot water tank 20 is wasted and resources and energy are wasted. And the timing will not be delayed and it will not fall into an unsanitary state.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The modification examples are listed below.
(1) In the first and second embodiments, the hot water flow rate from the hot water tank 20 is integrated for 48 hours, but this time setting can be changed as appropriate.
(2) In the first and second embodiments, the temperature environment in the hot water tank 20 is detected by the four hot water tank thermistors 35a, 35b, 35c, and 35d. The number of tank thermistors can be selected.
(3) In the first and second embodiments, the hot water flow rate sensor 46 provided in the hot water path 42 detects the hot water flow rate, but the hot water flow rate can also be calculated by the following calculation formula.
Flow rate detected by first flow sensor 67 or flow rate detected by second flow sensor 47 × (mixed water thermistor 44 detected temperature−feed water thermistor 48 detected temperature) / (hot water thermistor 50 detected temperature−feed water thermistor 48 detected temperature)
(4) In the cogeneration system of the first embodiment, if the power generation operation is not being performed, the power generation operation is forcibly performed to obtain the generated heat. If not, the power generation unit 110 is disposed. The hot water in the hot water storage tank 20 may be heated using the anti-freezing heater 123.
(5) When there is a possibility that bacteria have propagated in the hot water in the hot water tank 20, in the first embodiment, heat sterilization is performed, and in the second embodiment, the hot water in the hot water tank 20 is replaced. The selection of whether to perform heat sterilization or to replace the stored water may be performed automatically or manually by the user. For example, the stored water may be replaced when the amount of staying hot water is equal to or higher than a predetermined amount (can be set as appropriate) and the temperature of the staying hot water at that time is equal to or lower than a predetermined temperature (can be set as appropriate).

  In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The system diagram of the cogeneration system of 1st Example. The flowchart which shows the process of the hot water in the hot water storage tank of 1st Example. The flowchart which shows the process of the hot water in the hot water storage tank of 2nd Example.

Explanation of symbols

10: Hot water supply system 20: Hot water tank 22: Hot water heater 24: Mixing unit 35a: Hot water tank thermistor A, 35b: Hot water tank thermistor B, 35c: Hot water tank thermistor C, 35d: Hot water tank thermistor D
41: Warm water drainage path 42: Warm water path 43: Warm water path opening / closing valve 44: Outward thermistor 46: Warm water flow rate sensor 47: Second flow rate sensor 49: Hot water drainage path opening / closing valve 64: Hot water tap 65: Hot water supply thermistor 110: Power generation unit 128 : Circulation path, 128a: circulation return path, 128b: circulation outward path

Claims (2)

A hot water tank for storing hot water,
Heating means for heating the hot water stored in the hot water tank;
Dispersed and arranged in a plurality of locations in the vertical direction in the hot water tank, the hot water tank temperature distribution detection means for detecting the hot water temperature distribution in the hot water tank,
Sending hot water temperature detecting means for detecting the temperature of hot water sent from the hot water tank to the heating means,
A time measuring means for measuring a time during which the hot water temperature detected by the delivery hot water temperature detecting means is equal to or higher than a predetermined temperature;
Hot water flow rate detecting means for detecting the flow rate of hot water supplied from the hot water tank;
Hot water flow rate integrating means for integrating the flow rate detected by the hot water flow rate detecting means from the first predetermined time to the present time;
Prohibiting means to prohibit hot water supply from the hot water tank,
Sterilization means,
The sterilizing means is one in which the accumulated flow rate for the first predetermined time accumulated by the hot water flow rate integrating means is not more than the hot water tank capacity and the detected temperature is not less than the predetermined temperature among the temperature distribution detecting means in the hot water tank. When the amount of hot water up to the water level where the lowest one is located is less than or equal to the hot water volume obtained by subtracting the integrated flow rate from the hot water tank capacity, the time that is measured by the time measuring means by operating the prohibition means and heating means Cancels the prohibition means when becomes the second predetermined time,
The first predetermined time is a time that is slightly short of the time for bacteria to start breeding in the hot water in the hot water tank, the second predetermined time is slightly longer than the time required for high temperature sterilization, and the predetermined temperature is high temperature sterilization. Hot water storage hot water supply system characterized in that the temperature is slightly higher than the temperature required for the hot water. A hot water tank for storing hot water,
Dispersed and arranged in a plurality of locations in the vertical direction in the hot water tank, the hot water tank temperature distribution detection means for detecting the hot water temperature distribution in the hot water tank,
Hot water flow rate detecting means for detecting the flow rate of hot water supplied from the hot water tank;
Hot water flow rate integrating means for integrating the flow rate detected by the hot water flow rate detecting means from the first predetermined time to the present time;
Prohibiting means to prohibit hot water supply from the hot water tank,
A replacement means for replacing the hot water in the hot water tank;
A replacement flow rate detecting means for detecting the flow rate of the water replaced by the replacement means;
A switching means control means,
In the control means, the accumulated flow for the first predetermined time accumulated by the hot water flow accumulation means is less than the hot water tank capacity, and among the temperature distribution detection means in the hot water tank, the detected temperature is equal to or higher than the predetermined temperature. When the amount of hot water up to the water level where the lowest one is located is equal to or less than the amount of hot water obtained by subtracting the integrated flow rate from the hot water tank capacity, the prohibition means and the exchange means are operated, and the exchange flow rate detection means When the detected replacement flow rate reaches the predetermined flow rate, the prohibition means is released,
The hot water storage hot water supply system, wherein the predetermined flow rate is equal to or greater than a hot water tank capacity.

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