JP4546273B2 - Hot water system - Google Patents

Description

  The present invention relates to a hot water storage 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 when necessary using the hot water stored in the hot water storage tank. In particular, in a hot water storage-type hot water supply system, hot water that has been heated to a temperature higher than the hot water supply set temperature when the hot water supply operation is temporarily stopped immediately before switching from the heat storage use operation to the water heater use operation and then restarted. It is related with the technique which prevents that.

  In a hot water supply system that stores hot water heated by power generation heat or solar heat and supplies hot water, a hot water tank that stores hot water heated by power generation heat or solar heat, and hot water stored in a hot water storage tank A mixing unit for mixing tap water (cold water) and a water heater having a heater for heating the mixed water that has passed through the mixing unit as necessary are provided. In this type of hot water storage system, hot water stored in a hot water tank is adjusted to an appropriate temperature when necessary and used to supply hot water (hot water taps, bathtubs, showers, etc.), floor heating systems, etc. Or to use. In hot water supply operation, if hot water that is hotter than the hot water temperature required at the location where hot water is used (hot water supply set temperature) is stored in the hot water storage tank, the hot water sent from the hot water storage tank and tap water (cold water) are mixed in the mixing unit. By doing so, it cools to the required temperature and supplies hot water (referred to as heat storage operation). If hot water having a temperature lower than the hot water temperature (hot water set temperature) required in the hot water use location is stored in the hot water storage tank, the hot water is heated with a hot water heater or the like (referred to as hot water heater operation).

  In the hot water supply system as described above, if the hot water in the hot water storage tank becomes insufficient during the hot water supply operation in the heat storage use operation, the hot water supply operation is continued by switching from the heat storage use operation to the water heater use operation. When the hot water temperature entering the mixing unit falls below the hot water supply set temperature, the hot water heater or the like is ignited and the operation is switched to the hot water heater using operation. When switching from the heat storage use operation to the water heater use operation, the hot water supply temperature tends to become unstable. A hot water supply system in which the hot water supply temperature changes during use is uncomfortable for the user and unusable.

  Patent Document 1 discloses a technique for stabilizing a hot water supply temperature when switching from a heat storage use operation to a water heater use operation. When the hot water temperature entering the mixing unit is lower than the hot water supply set temperature and the operation is switched from the heat storage use operation to the hot water supply use operation, there is hot water adjusted to the hot water supply set temperature between the mixing unit and the water heater. If heating by the water heater is started at this time, the hot water adjusted to the hot water supply set temperature is heated, so that it is overheated to the hot water supply set temperature or higher. In the technique of Patent Document 1, the mixed water is used when the hot water temperature entering the mixing unit is lower than the hot water supply set temperature after the hot water temperature is lower than the reference temperature approximate to the hot water supply set temperature during the heat storage operation. The flow rate is integrated, and heating of the water heater is started when the integrated mixed water flow rate becomes equal to the pipe capacity between the mixing unit and the water heater. According to this technology, when switching from the heat storage use operation to the water heater use operation, hot water having a temperature higher than the hot water supply set temperature is prevented from being supplied.

  The technique of Patent Document 1 uses a hot water supply not only when switching from a heat storage operation to a water heater use operation during a continuous hot water supply operation, but also when the heat storage operation is finished and then the hot water operation is started. It can also be useful when driving is selected. When there is a hot water supply request again after a short while after stopping the heat storage use operation, if the hot water temperature in the hot water storage tank is lower than the hot water supply set temperature due to heat radiation, the water heater use operation is selected. For example, when hot water storage operation is stopped when intermittent hot water supply operation is performed, such as when washing dishes or using a shower, the temperature of hot water available in the hot water tank May be in a state just before the hot water supply set temperature falls below (hot water runs out). In this case, consider a case where a hot water supply request is made again after a short stoppage time. If the stop time of the hot water supply operation is short, the amount of heat released from the hot water in the hot water tank is also small. However, the temperature of the hot water in the hot water storage tank slightly decreases due to the heat radiation during the stop time, and the hot water temperature in the hot water storage tank at the time of the hot water supply request may be lower than the hot water supply set temperature. In this case, the water heater use operation is selected. When the hot water supply operation is stopped during the heat storage use operation, hot water having a temperature equal to or higher than the hot water supply set temperature remains in the pipe between the hot water tank and the hot water heater. While the hot water supply operation is stopped, the heat dissipation of the staying hot water in the pipe also proceeds. However, if the hot water supply operation is stopped for a short time, the heat release amount of the staying hot water is also small. Therefore, when a hot water supply request is made again, hot water having a temperature that is lower than the hot water supply set temperature but approximate to the hot water supply set temperature exists in the pipe. When heating by the water heater is started at this time, hot water having a temperature approximate to the hot water supply set temperature staying in the pipe may be overheated to a hot water supply set temperature or higher. According to the technique of Patent Literature 1, even in such a case, it is possible to prevent hot water having a temperature higher than the hot water supply set temperature from being supplied.

JP 2003-42542 A

However, the phenomenon at the time of re-bathing is not limited to the above phenomenon. If the stop time of the hot water supply operation becomes longer, the temperature drop due to the heat radiation of the hot water in the hot water storage tank or the hot water in the pipe becomes larger. Applying the technique of Patent Document 1 until the hot water supply is requested in a state where the hot water temperature in the hot water tank or the hot water temperature in the pipe is lowered to a temperature approximate to the outside air temperature, the low-temperature water in the pipe flows. Heating by the water heater will be started after cutting. Even if the hot water temperature in the pipe is low temperature water that does not rise above the hot water supply set temperature even if it is heated by the water heater, heating by the water heater starts after the low temperature water in the pipe has completely flowed out. It will be. In this case, water and time are wasted before heating by the water heater is started, which is very inconvenient.
The present invention provides a hot water supply system capable of preventing hot water having a temperature higher than the hot water supply set temperature from being supplied or water and time being wasted when hot water is heated by heating means. It is an object.

The hot water supply system of the present invention is a hot water storage tank that stores hot water, a mixing unit that mixes hot water and tap water from the hot water storage tank, and an adjustment of the mixing ratio, and heats mixed water from the mixing unit as necessary. Heating means, hot water temperature detecting means for detecting the hot water temperature upstream from the mixing unit, mixed water temperature detecting means for detecting the mixed water temperature downstream from the mixing unit, and a hot water supply setting storing hot water supply set temperature A temperature storage means, a mixed water flow rate detecting means for detecting the flow rate of the mixed water, a mixed water flow rate integrating means for integrating the mixed water flow rate detected by the mixed water flow rate detecting means, and a controller are provided.
The controller is configured such that the flow rate detected by the mixed water flow rate detection unit is equal to or higher than a predetermined flow rate, the hot water temperature detected by the hot water temperature detection unit is equal to or lower than a first predetermined temperature, and is detected by the mixed water temperature detection unit. When the mixed water temperature is equal to or higher than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, the heating unit is operated when the integrated flow rate integrated by the mixed water flow rate integration unit becomes the predetermined integrated flow rate. Further, the controller has a flow rate detected by the mixed water flow rate detection means that is equal to or higher than a predetermined flow rate, a hot water temperature detected by the hot water temperature detection means is equal to or lower than a first predetermined temperature, and the mixed water temperature detection means When the detected mixed water temperature is lower than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, the heating means is immediately operated. The first predetermined temperature is a temperature determined based on the hot water supply set temperature, and the second predetermined temperature is a temperature determined based on the degree of the rising temperature of the hot water when heated with the minimum heating amount of the heating means. is there.

In the present invention, when the flow rate detected by the mixed water flow rate detection means is equal to or higher than a predetermined flow rate, it is determined that a hot water supply request has been made. If the temperature of the hot water upstream from the mixing unit is equal to or lower than the first predetermined temperature (usually the hot water supply set temperature), it is determined that the hot water in the hot water tank cannot be used without heating, and is heated by the heating means. Then do hot water supply.
When hot water is supplied by heating by the heating means, if high-temperature water stays downstream from the mixing unit, the high-temperature water may be heated by the heating means and rise to a hot water supply set temperature or higher. . In the present invention, when the mixed water temperature downstream of the mixing unit is equal to or higher than the temperature obtained by subtracting the second predetermined temperature (for example, 10 ° C. exemplified in the embodiment) from the hot water supply set temperature, the inside of the piping on the downstream side of the mixing unit It is determined that there is a possibility that the temperature of the hot water staying in the hot water stays higher than the preset hot water supply temperature even when the hot water staying at the minimum heating amount of the heating means. In this case, the heating unit operates when the integrated flow rate integrated by the mixed water flow rate integration unit reaches a predetermined integrated flow rate (for example, the pipe capacity between the downstream side of the mixing unit and the downstream side of the heating unit). Let As a result, after the hot staying hot water has passed through the location where the heating means is provided, the heating means starts operating, and the staying hot water is prevented from being heated by the heating means and being heated above the hot water supply set temperature. can do.
On the other hand, when the mixed water temperature downstream of the mixing unit is lower than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, the hot water staying in the piping on the downstream side of the mixing unit is the minimum heating amount of the heating means. Even if it is heated at, it is determined that the temperature does not rise above the hot water supply set temperature. At this time, as described above, if the heating unit is operated when the integrated flow rate integrated by the mixed water flow rate integration unit reaches the predetermined integrated flow rate, the hot water supply setting is performed even if the heating unit is heated at the minimum heating amount. The heating means starts operating only after low-temperature water that does not rise above the temperature passes through the location where the heating means is provided. The time until the heating means starts operating is useless, and the low-temperature water that flows until hot water at the hot water supply set temperature is supplied is also useless. In this invention, when the temperature of the mixed water downstream from the mixing unit is less than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, the heating means is immediately operated. As a result, the time required for hot water supply at the hot water supply set temperature can be shortened, and the amount of low-temperature water flowing until hot water supply at the hot water supply set temperature can be suppressed.
In the hot water supply system of the present invention, when the hot water is heated by the heating means, the operation start timing of the heating means is changed according to the temperature of the hot water staying in the piping on the downstream side of the mixing unit. Before the hot water is supplied at the hot water supply set temperature, it is possible to prevent hot water having a temperature higher than the hot water supply set temperature from being supplied or water and time from being wasted.

In the hot water supply system of the present invention, it is preferable that the second predetermined temperature is equal to or higher than the temperature range at which the temperature of the hot water rises when heated by the minimum heating amount of the heating means.
In this way, it is accurately determined whether or not the temperature of the hot water or cold water staying downstream from the mixing unit will rise above the hot water supply set temperature when heated with the minimum heating amount of the heating means. can do.

Hereinafter, preferred embodiments of the present invention will be described.
(Mode 1) If the hot water temperature detected by the thermistor at the upper part of the hot water tank is equal to or higher than the first predetermined temperature, the heat storage use operation is performed, and if it is lower than the first predetermined temperature, the water heater use operation is performed.
(Mode 2) The predetermined integrated flow rate is equal to the pipe capacity between the mixed water temperature detection means and the hot water supply temperature detection means for detecting the hot water supply temperature downstream of the heating means.
(Embodiment 3) A mixing water temperature indicating means for instructing the mixing water temperature to the mixing unit is provided. If the temperature of the hot water downstream from the mixing unit is equal to or higher than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, mixing is performed. The heating means is operated when the integrated flow integrated by the water flow integration means reaches a predetermined integrated flow, and the mixed water temperature downstream from the mixing unit is equal to or higher than the temperature obtained by subtracting the third predetermined temperature from the hot water supply set temperature. If so, a temperature obtained by subtracting the third predetermined temperature from the hot water supply set temperature is instructed by the mixed water temperature instructing means. The second predetermined temperature is larger than the increase range of the hot water temperature (steady temperature increase range) that rises when heated with the minimum heating amount of the heating means, and the third predetermined temperature is when heated with the minimum heating amount of the heating means. It is equal to the rising width of the rising hot water temperature (steady temperature rising width).

An embodiment embodying a 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 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 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 114 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 is 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 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 reformer 112, the fuel cell 114, the burner 131, the heat medium three-way valve 122, the heat medium pump 127, and the heat medium cooling fan 119 are controlled by the controller 21.

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 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, hot 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 portion 20a provided at the uppermost portion of the hot water storage tank 20 even if the hot water storage tank 20 is not fully stored. 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.

  An upper thermistor 35 is attached at a location 5 liters from the top of the hot water tank 20. The upper thermistor 35 detects the temperature in the hot water tank 20. A detection signal from the upper thermistor 35 is output to the controller 21. The detected temperature of the upper thermistor 35 is used not only for hot water temperature control but also for calculating 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 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 from 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. 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.
The 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 hot water path 51. A second flow rate sensor 47 is attached to the hot 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 hot 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 hot 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, a bypass path is formed that branches from the upstream side of the burner heat exchanger 52 in the hot water path 51, passes through the bypass pipe 37, and joins the downstream side of the burner heat exchanger 52 in the hot water path 51. The 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 hot 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 installed 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 route 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 hot water filling operation to the bathtub 79 is performed by the water pressure applied to the hot 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 into 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, water is heated using the generated heat generated during power generation in the power generation unit 110 and stored in the hot water storage tank 20, and the stored hot water can be used when necessary. it can. Moreover, if there is no hot water which can be utilized in the hot water tank 20, the low temperature water in the hot water tank 20 can be heated and utilized by the hot water heater 22 provided in the hot water system 10.
The temperature control of the hot water supply temperature in the cogeneration system of the present embodiment will be described. As shown in FIG. 2, in step S10, it is determined whether or not the flow rate detected by the second flow rate sensor 47 in the water heater 22 is 2.7 liters / min or more. If the detected flow rate of the second flow rate sensor 47 is 2.7 liter / min or more (if YES in step S10), it is determined that the hot water tap 64 has been opened and a hot water supply request has been made, and the process proceeds to step S12. In step S12, integration of the detected flow rate of the second flow rate sensor 47 is started.
It progresses to step S14 and it is discriminate | determined whether the temperature which the upper thermistor 35 provided in the upper part of the hot water storage tank 20 detects is less than the temperature which added 1 degreeC to the hot water supply preset temperature set by the user. If the detected temperature of upper thermistor 35 is equal to or higher than [hot water supply set temperature + 1 ° C.] (NO in step S14), it is determined that a hot water supply operation using heat storage can be performed, and the process proceeds to step S30. Perform heat storage operation.

In the heat storage utilization operation in step S30, the hot water in the hot water storage tank 20 is sent to the mixing unit 24 and mixed with tap water, and the hot water is adjusted to a hot water supply set temperature to supply hot water. When the hot water in the hot water tank 20 decreases and there is no hot water available (when the hot water runs out), the operation is switched to the hot water heater using operation. Step S30 is displayed as a heat storage use operation. However, if the hot water in the hot water storage tank 20 runs out as a result of continuously performing the heat storage use operation, the operation is switched to the water heater use operation. Perform use operation. When switching from the heat storage utilization operation to the water heater utilization operation during a series of hot water supply operations, the water heater utilization operation after the switching is also executed in step S30.
When switching from the heat storage use operation to the water heater use operation, the hot water supply temperature tends to become unstable with a change in the heating amount at the start of heating of the water heater 22 or a rapid temperature drop in hot water when the hot water runs out. In the hot water supply system of the present embodiment, the hot water set temperature is stabilized by executing the following temperature control when switching from the heat storage use operation to the water heater use operation.
Since the burner heat exchanger 52 has a length, the water on the downstream side of the burner heat exchanger 52 and the water on the upstream side at the start of heating of the burner 56 pass through the burner heat exchanger 52. There is a difference in the temperature rise width that is heated by the water, and the temperature rise width increases as the water is on the upstream side (hereinafter, while the water on the upstream side of the burner heat exchanger 52 passes through the burner heat exchanger 52). In addition, the temperature increase width that is heated by the minimum heating amount of the burner 56 may be referred to as a steady temperature increase width). Therefore, in the hot water supply system 10 of the present embodiment, when the detected temperature of the upper thermistor 35 falls below [the hot water supply set temperature + 1 ° C.], the temperature of the mixed water entering the water heater 22 is changed to the hot water at the start of the heating operation of the water heater 22. The temperature is lowered at a change rate of the temperature rise range, and the hot water when the temperature starts to drop reaches the outlet of the burner heat exchanger 52 of the hot water heater 22 and the hot water when the temperature has been lowered (at this time) When the hot water temperature reaches [the hot water supply set temperature−the steady temperature rise width] reaches the inlet of the burner heat exchanger 52 of the water heater 22, the burner 56 starts to burn with the minimum heating amount. Thereby, the temperature of the hot water sent out from the burner heat exchanger 52 can be stabilized at the hot water supply set temperature immediately after the start of heating.
Further, in the hot water supply system 10, the mixing unit 24 after the integrated flow rate after the detected temperature of the upper thermistor 35 falls below [the hot water supply set temperature + 1 ° C.] exceeds the flow rate corresponding to the capacity of the burner heat exchanger 52. The temperature of the mixed water to be temperature-controlled is adjusted so as to be [hot-water supply set temperature-steady temperature rise width]. When the detected temperature of the upper thermistor 35 falls below [hot water supply set temperature−steady temperature rise width], the mixing unit 24 starts to control the mixing ratio so that the detected temperature of the mixed water thermistor 54 decreases at 1 ° C./sec. The temperature decrease rate of 1 ° C./sec of the mixed water is a gradual rate, and can be sufficiently dealt with by controlling the change rate of the heating amount in the water heater 22. Therefore, the hot water supply temperature at the time of switching from the heat storage use operation to the water heater use operation can be stabilized at the hot water supply set temperature.

  When the heat storage utilization operation is performed in step S30 or the water heater utilization operation is performed following the heat storage utilization operation, if the detected flow rate of the second flow sensor 47 becomes 2.0 liters / min or less in step S28 ( If YES), it is determined that the hot water tap 64 has been closed, and the hot water supply operation is stopped.

On the other hand, if the detected temperature of the upper thermistor 35 is lower than [hot water supply set temperature + 1 ° C.] (if YES) in step S14, it is determined that it is impossible to perform the hot water supply operation using heat storage. In order to perform the container using operation, the process proceeds to step S16. Note that “1 ° C.” of [hot water supply set temperature + 1 ° C.] used for the determination in step S14 is a switching correction amount.
In step S16, it is determined whether or not the temperature detected by the mixed water thermistor 54 provided in the vicinity of the mixed water outlet 24c of the mixing unit 24 is equal to or higher than a temperature obtained by subtracting 10 ° C. from the hot water supply set temperature.

  When the heat storage operation is performed and the hot water supply operation is stopped in a state where the available high temperature water remains in the hot water storage tank 20, the available high temperature water remains in the piping of the hot water supply path. If time passes in this state, the temperature of the hot water near the upper thermistor 35 in the upper part of the hot water tank 20 and the temperature of the hot water in the pipe are lowered by heat radiation. For example, it is assumed that the hot water supply operation is stopped immediately before the hot water runs out, and the detected temperature of the upper thermistor 35 is slightly higher than [hot water supply set temperature + 1 ° C.]. Thereafter, if the heat storage is not performed while the hot water supply operation is stopped and the heat radiation proceeds, the temperature of the hot water in the hot water storage tank 20 decreases. If the stop time of the hot water supply operation is not so long, a state may occur in which the detected temperature of the upper thermistor 35 at the start of the hot water supply operation is slightly lower than [hot water supply set temperature + 1 ° C.]. In such a state, since the heat of the hot water staying in the piping of the hot water supply passage is also little, a state in which the detected temperature of the mixed water thermistor 54 is not less than [hot water supply set temperature −10 ° C.] may occur. When the detected temperature of the mixed water thermistor 54 is equal to or higher than [hot water supply set temperature −10 ° C.], the temperature of the hot water downstream from the mixed water thermistor 54 is likely to be higher. Due to the configuration of the hot water supply system 10, the temperature of the high temperature water staying in the pipe downstream from the mixing unit 24 cannot be lowered, so that the high temperature water is directly sent to the burner heat exchanger 52. The steady temperature rise width in this embodiment is 8 ° C., and “10 ° C.” of “hot water supply set temperature−10 ° C.” used for the determination in step S 16 is the mixed water thermistor in the steady temperature rise width of the water heater 22. In consideration of the assumed temperature difference between the hot water temperature in the vicinity of 54 and the hot water temperature in the burner heat exchanger 52, the temperature is set to be equal to or greater than the steady temperature rise. If the burner 56 is ignited and burns with the minimum heating amount of the burner 56 when there is high-temperature water in the burner heat exchanger 52 that is [hot-water supply set temperature −10 ° C.] or higher, the high-temperature water is heated and further heated As a result, hot water having a temperature higher than the hot water supply set temperature may be supplied.

In order to prevent the above problem, if the detected temperature of the mixed water thermistor 54 is [hot water supply set temperature-10 ° C.] or more (if YES) in step S16, it is determined that the hot water temperature in the pipe is high. Then, the process proceeds to step S18. In step S18, it is determined whether or not the detected temperature of the mixed water thermistor 54 is equal to or less than [hot water supply set temperature−steady temperature rise width]. If the detected temperature of the mixed water thermistor 54 exceeds [the hot water supply set temperature-steady temperature rise width] (NO in step S18), when this hot water is sent to the burner heat exchanger 52, the burner 56 is When ignited and heated with the minimum heating amount of the burner 56, the temperature rises to a temperature higher than the hot water supply set temperature. Therefore, if the detected temperature of the mixed water thermistor 54 is higher than [hot water supply set temperature−steady temperature rise width] (NO in step S18), the process proceeds to step S20, and the mixing unit 24 determines the mixed water thermistor 54. The temperature is adjusted so that the detected temperature becomes [hot water supply set temperature−steady temperature rise width].
If the temperature of the hot water sent out from the hot water storage tank 20 decreases and the detected temperature of the mixed water thermistor 54 is equal to or lower than [hot water supply set temperature−steady temperature rise width] in step S <b> 18 (if YES), the mixed water thermistor 54. Since it is not necessary to adjust the temperature so that the detected temperature becomes [hot-water supply set temperature-steady temperature rise width], the process proceeds to step S22.

In step S22, it is determined whether or not the integrated flow rate of the second flow rate sensor 47 is equal to or greater than the switching preparation flow rate. The switching preparation flow rate is a flow rate corresponding to the pipe capacity from the mixed water thermistor 54 to the hot water supply thermistor 65 provided on the downstream side of the burner heat exchanger 52. When water is passed until the integrated flow rate of the second flow rate sensor 47 becomes equal to or higher than the switching preparation flow rate (until YES in step S22), the hot water that has remained [hot water set temperature -10 ° C] or higher has remained. Pass through 52. At the same time, hot water that has started to be adjusted to a temperature lower than [hot water supply set temperature−steady temperature rise range] is sent into the burner heat exchanger 52. If the integrated flow rate of the second flow rate sensor 47 is greater than or equal to the switching preparation flow rate (if YES in step S22), the process proceeds to step S24.
In step S16, if the detected temperature of the mixed water thermistor 54 is lower than [hot water supply set temperature −10 ° C.] (if NO), the temperature of the hot water upstream of the burner heat exchanger 52 is It is determined that the hot water is less than (set temperature−steady temperature rise range)], and the process proceeds from step S16 to step S24.

In step S24, the burner 56 is ignited and the operation is switched to the hot water heater utilization operation. Since the hot water in the burner heat exchanger 52 when the burner 56 is ignited is hot water less than [hot water supply set temperature−steady temperature rise width], even if it is heated with the minimum heating amount of the burner 56, it is equal to or higher than the hot water supply set temperature. Never become.
The burner 56 is ignited, and the process proceeds to step S26, in which the temperature is adjusted so that the detected temperature of the hot water supply thermistor 65 becomes the set hot water temperature. In step S28, when the detected flow rate of the second flow rate sensor 47 is 2.0 liters / min or less (when it becomes YES), it is determined that the hot water tap 64 is closed, and the hot water supply operation is stopped.

  For example, the hot water supply operation is intermittently performed when washing dishes or using a shower while taking a bath. When the heat storage use operation is stopped, the temperature of the hot water available in the hot water storage tank 20 is just before the hot water supply set temperature falls (hot water runs out), and a hot water supply request is made again after a short operation stop time. In this case, if the hot water supply operation is stopped for a short time, the heat dissipation amount of the hot water in the hot water storage tank 20 is also small. However, if the temperature of the hot water in the hot water storage tank 20 drops slightly due to heat dissipation during this stop time, and the hot water temperature in the hot water storage tank 20 at the time of requesting hot water supply falls below the hot water supply set temperature, the hot water heater using operation is performed. It will be. When the hot water supply operation is stopped during the heat storage use operation, the hot water at the hot water supply set temperature stays in the pipe between the hot water tank 20 and the hot water heater 22. While the hot water supply operation is stopped, the heat dissipation of the staying hot water in the pipe also proceeds. However, if the hot water supply operation is stopped for a short time, the heat release amount of the staying hot water is also small. Therefore, when a hot water supply request is made again, there may be hot water having a temperature that is lower than the hot water supply set temperature but approximate to the hot water supply set temperature. When heating by the hot water heater 22 is started at this time, hot water having a temperature approximating the hot water supply set temperature staying in the pipe is heated by the minimum heating amount of the burner 56 and is heated to a temperature higher than the hot water supply set temperature. Hot water will be supplied.

In this embodiment, when the hot water supply operation is performed in the operation using the hot water heater, the temperature of the hot water staying in the piping on the downstream side of the mixing unit 24 is detected, and the hot water supply setting is performed even if the burner 56 is heated with the minimum heating amount. It is possible to determine whether or not the temperature is likely to rise above the temperature. When it is determined that the temperature of the staying hot water is higher than the hot water supply set temperature when heated by the minimum heating amount of the burner 56, the mixed water thermistor 54 and the hot water supply thermistor 65 The burner 56 of the water heater 22 is not ignited until an integrated flow rate corresponding to the pipe capacity is detected. That is, the burner 56 is ignited at the timing when the staying hot water passes through the burner heat exchanger 52 of the water heater 22. As a result, it is possible to prevent high-temperature staying hot water from being heated by the burner 56 to rise in temperature, and hot water to be supplied at or above the hot water supply set temperature.
At this time, the hot water temperature that is supplied before the hot water is supplied at the set hot water temperature is lower than the hot water set temperature, but is higher than the tap water temperature, so there is very little discomfort for the user. .
Further, in this embodiment, if it is determined that the temperature of the staying hot water is a low temperature that does not rise above the hot water supply set temperature even when heated by the minimum heating amount of the burner 56, the burner of the hot water heater 22 is immediately 56 is ignited. There is no waiting until the integrated flow rate corresponding to the pipe capacity between the mixed water thermistor 54 and the hot water supply thermistor 65 is detected. As a result, it is possible to reduce the time until the burner 56 is ignited and the amount of low-temperature water that flows until the hot water at the hot water supply set temperature is supplied.
In the hot water supply system 10 of the present embodiment, when performing the hot water supply operation using the hot water heater, the ignition timing of the burner 56 is changed according to the temperature of the hot water remaining in the piping on the downstream side of the mixing unit 24 to Before the hot water is supplied at the set temperature, it is possible to prevent hot water having a temperature higher than the hot water set temperature from being supplied, and water and time from being wasted.

In this embodiment, in step S14, when the upper temperature of the hot water tank 20 is equal to or lower than [hot water supply set temperature + 1 ° C.] (an example of the first predetermined temperature), the hot water heater using operation is selected. The temperature at which the hot water heater utilization operation is selected is a temperature obtained by adding a predetermined temperature to the hot water supply set temperature. The reason why the predetermined temperature is applied is that the hot water passing through the water heater 22 is cooled unless the water heater 22 is heated. In this embodiment, the hot water is cooled by 1 ° C. while passing through the water heater 22 if not heated, so that [hot water supply set temperature + 1 ° C.] is set as the first predetermined temperature. This is different for each embodiment.
In this embodiment, in step S16, it is selected whether to immediately ignite the burner 56 or to ignite it with a delay depending on whether the temperature of the mixed water detected by the mixed water thermistor 54 is equal to or higher than [hot water supply set temperature−10 ° C.]. The second predetermined temperature (10 ° C. in this case) subtracted from the hot water supply set temperature is larger than the steady temperature rise (in this case, 8 ° C.). This is because the hot water temperature in the burner heat exchanger 52 may be about 2 ° C. higher than the hot water temperature in the vicinity of the mixed water thermistor 54 at the time of ignition of the burner. Due to the difference in the amount of heat release, the hot water in the burner heat exchanger 52 may be warmer than the hot water near the mixed water thermistor 54. In the present invention, the temperature obtained by adding the temperature difference between hot water in the vicinity of the mixed water thermistor 54 and the burner heat exchanger 52 (in this case, 2 ° C.) to the steady temperature rise (in this case, 8 ° C.) is set as the second predetermined temperature. However, this differs for each embodiment. If the temperature difference between the hot water temperature in the vicinity of the mixed water thermistor 54 and the burner heat exchanger 52 is negligible, the steady temperature rise width may be set to the second predetermined temperature.

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.
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 which concerns on a present Example. The flowchart which shows the hot water supply temperature control process at the time of the hot water supply start in a present Example.

Explanation of symbols

10: Hot water supply system 20: Hot water storage tank 22: Hot water heater 24: Mixing unit 35: Upper thermistor 47: Second flow sensor 52: Burner heat exchanger 54: Mixed water thermistor 56: Burner 64: Hot water tap 65: Hot water thermistor 110: Power generation unit

Claims (2)

A hot water tank for storing hot water,
A mixing unit that mixes hot water and tap water from a hot water tank and adjusts the mixing ratio;
Heating means for heating the mixed water from the mixing unit as needed;
Hot water temperature detecting means for detecting the temperature of the hot water upstream from the mixing unit;
A mixed water temperature detecting means for detecting the mixed water temperature downstream from the mixing unit;
Hot water set temperature storage means for storing hot water set temperature;
A mixed water flow rate detecting means for detecting a flow rate of the mixed water;
Mixed water flow rate integration means for integrating the mixed water flow rate detected by the mixed water flow rate detection means;
With a controller,
The controller has the following controls:
The flow rate detected by the mixed water flow rate detection means is not less than a predetermined flow rate, the hot water temperature detected by the hot water temperature detection means is not more than the first predetermined temperature, and the mixed water temperature detected by the mixed water temperature detection means Is equal to or higher than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, the heating unit is operated when the integrated flow rate integrated by the mixed water flow rate integration unit becomes the predetermined integrated flow rate,
The flow rate detected by the mixed water flow rate detection means is not less than a predetermined flow rate, the hot water temperature detected by the hot water temperature detection means is not more than the first predetermined temperature, and the mixed water temperature detected by the mixed water temperature detection means Is less than the temperature obtained by subtracting the second predetermined temperature from the hot water supply set temperature, the heating means is immediately operated,
The first predetermined temperature is a temperature determined based on the hot water supply set temperature,
The second predetermined temperature is a hot water supply system , which is a temperature determined based on a degree of rising temperature of hot water when heated by the minimum heating amount of the heating means .   2. The hot water supply system according to claim 1, wherein the second predetermined temperature is equal to or higher than a temperature range in which the temperature of the hot water rises when heated by the minimum heating amount of the heating unit.

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