JP4488884B2 - Hot water system - Google Patents

Description

  The present invention relates to a 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 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, the present invention relates to a technique for shortening the time until hot water adjusted to a hot water supply set temperature starts to be supplied to a hot water use location.

  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 such a hot water storage type hot water supply system, hot water stored in a hot water storage tank is adjusted to an appropriate temperature when necessary, and hot water is supplied to hot water use places (hot water tap, bathtub, shower, floor heating system, etc.). If hot water hotter than the hot water temperature required at the hot water use location is stored in the hot water tank, the hot water sent from the hot water tank and tap water (cold water) are mixed with the mixing unit and cooled to the required temperature. Hot water. If hot water having a temperature lower than the hot water temperature required at the hot water use location is stored in the hot water storage tank, the hot water is heated by a heater. Even when heating with a heater, the amount of heat required is smaller than when heating tap water. The hot water storage type hot water supply system has high overall energy efficiency and can reduce the running cost for hot water supply.

The temperature of the mixed water in the hot water supply path after the hot water supply is stopped decreases with time. If a certain amount of time elapses before the next hot water supply, low temperature water that has cooled in the hot water supply path will flow out at the start of the next hot water supply. Further, the hot water adjusted to the hot water supply set temperature by the mixing unit is deprived of heat while passing through the cold piping, and the temperature drops. Therefore, if a certain amount of time has elapsed since the previous hot water supply, at the start of the next hot water supply, low temperature water that does not reach the hot water supply set temperature is supplied, and it takes time until hot water adjusted to the hot water supply set temperature starts to be supplied. Cost. In this specification, starting the hot water supply in a state where the temperature of the hot water supply pipe or the mixed water in the pipe is lowered may be referred to as a cold start. In addition, from the start of hot water supply until the hot water adjusted to the hot water supply set temperature starts to be supplied is referred to as a start-up, and sometimes the hot water adjusted to the hot-water supply set temperature is started to be in a state of being supplied with hot water. .
At the cold start time, it takes time until the mixed water adjusted to the desired hot water temperature starts to open (starts up) after the hot water tap is opened.
Even when hot water is supplied by heating with a heater, it takes time until the hot water adjusted to the desired hot water temperature starts to open after the hot water tap is opened. However, since the pipe capacity from the heater to the hot water tap is small, the time is relatively short. On the other hand, since the piping capacity from the mixing unit to the hot water tap is large, the rise time in the case of supplying hot water without heating with a heater becomes long. In particular, the influence of the piping capacity inside the heater is large, and the latent heat recovery type water heater that improves the efficiency of thermal efficiency by placing a condenser inside has a particularly large piping capacity inside the heater. The difference between the rise time when the hot water is supplied without heating and the rise time when the hot water is heated with the heater is increased.
The present invention provides a technique for reducing the difference between the rise time when hot water is supplied without heating with a heater and the rise time when hot water is supplied with a heater.

  Patent Document 1 discloses a technique for shortening the rise time at the cold start. The hot water supply apparatus of Patent Document 1 includes means for heating the hot water supply pipe, and when the temperature of the hot water supply pipe is low, the hot water supply pipe is heated by the heating means. According to this technique, it is possible to prevent the hot water from the hot water tank from being deprived of heat while flowing through the hot water supply pipe, and the rise time can be shortened.

JP-A-6-300296

In the hot water storage type hot water supply system, when hot water having a temperature higher than the hot water supply set temperature is stored in the hot water storage tank, hot water is supplied using the hot water in the hot water storage tank without using the heater. When hot water is not stored in the hot water tank or when the temperature of the hot water stored is low, the hot water is heated with a heater.
The hot water supply path when using hot water from a hot water tank is from the hot water tank to the hot water tap, and compared to the hot water supply path when using a heater to supply hot water, the length of the pipe from the hot water tank Just long. Therefore, the heat loss at the cold start is large accordingly. Even when hot water from the hot water tank is supplied without being heated by the heater, the mixed water adjusted in temperature by the mixing unit passes through the heat exchanger of the heater. The heat dissipation in the heat exchanger of the heater is large. Moreover, at the time of cold start, low-temperature water stays in the heat exchanger of the heater, and much heat is taken away when the mixed water whose temperature is adjusted passes through the heat exchanger. Therefore, when the cold start is performed using the hot water in the hot water storage tank, the rise time is longer and the feeling of use is worse than when the cold start is performed using the heater.

  The graph of FIG. 6 shows the transition of the mixed water temperature (shown by a broken line) measured at the outlet of the mixing unit and the hot water temperature supplied from the hot water tap (shown by a solid line) at the cold start. The hot water supply temperature rises after the temperature rise of the mixed water temperature. At the start of hot water supply, the temperature of the mixed water rises quickly, but the hot water supply temperature is deprived of heat from the cold piping between the mixing unit and the hot water tap or the low-temperature water staying in the heat exchanger of the heater. As shown in the figure A, the temperature rise is stagnant. Even if the mixed water temperature has risen to the hot water supply set temperature, the hot water supply temperature does not readily rise to the hot water supply set temperature, and the rise time becomes long.

  In the technique of Patent Document 1, a heating means for heating a hot water supply pipe is provided in the vicinity of the outlet of the hot water storage tank to heat the hot water supply tank, and the rise time at the cold start when hot water is supplied using hot water in the hot water storage tank is shortened. However, since it is necessary to provide a separate heating means, the manufacturing cost of the system is increased.

  An object of the present invention is to provide a hot water supply system that can shorten the rise time at the time of cold start to supply hot water using hot water from a hot water tank and can be manufactured at low cost.

The hot water supply system of the present invention includes a hot water storage tank for storing hot water, a mixing unit that mixes hot water from the hot water storage tank and tap water, and an adjustable mixing ratio, and hot water temperature detection that detects the temperature of the hot water upstream from the mixing unit. Means, a mixed water temperature detecting means for detecting a mixed water temperature downstream from the mixing unit, a hot water supply temperature storing means for storing a hot water supply set temperature, and a mixed water temperature indicating means for instructing the mixing water temperature to the mixing unit And a mixed water flow rate integration means for integrating the mixed water flow rate after starting the flow of the mixed water.
The mixed water temperature indicating means of the present invention is such that the mixed water temperature detected by the mixed water temperature detecting means is not higher than the first predetermined temperature, and the hot water temperature detected by the hot water temperature detecting means is not lower than the second predetermined temperature, When the integrated flow integrated by the mixed water flow integration means is less than or equal to the predetermined integrated flow, a mixed water temperature higher by a predetermined temperature than the hot water supply set temperature is indicated, and when the integrated flow is above the predetermined integrated flow, the hot water supply setting Indicate the temperature.

In the present invention, when the temperature of the mixed water downstream from the mixing unit is equal to or lower than a first predetermined temperature (for example, 25 ° C. as exemplified in the embodiment), it is determined that the cold start has occurred. If the temperature of the hot water upstream from the mixing unit is equal to or higher than the second predetermined temperature (usually a hot water supply set temperature), it is determined that the hot water can be supplied without heating by using the hot water in the hot water storage tank. When it is a cold start and hot water is supplied without using the hot water in the hot water tank, the mixing water temperature is instructed to the mixing unit by a predetermined temperature higher than the hot water supply set temperature. During a cold start that is not heated by the heater, the temperature of the hot water supply pipe can be increased by adjusting the temperature at a temperature higher than the hot water supply set temperature by the mixing unit. If the temperature in the hot water supply pipe rises quickly, the heat dissipation loss when the mixed water passes through the hot water supply pipe is suppressed, so that the rising speed of the hot water temperature supplied from the hot water tap can be increased. From this, it becomes possible to shorten the rise time at the time of cold start which is not heated by the heater.
When the integrated flow rate of the mixed water reaches a predetermined integrated flow rate, the hot water supply set temperature is instructed to the mixing unit. Before the mixed water adjusted to a temperature higher than the hot water supply set temperature begins to be supplied from the hot water supply point, the temperature of the mixed water delivered from the mixing unit is switched to the hot water set temperature, so hot water higher than the hot water set temperature is It is possible to prevent the hot water from being fed from.

  In another hot water supply system of the present invention, the mixed water temperature indicating means is such that the mixed water temperature detected by the mixed water temperature detecting means is equal to or lower than a first predetermined temperature, and the hot water temperature detected by the hot water temperature detecting means is When the temperature is equal to or higher than the second predetermined temperature, a mixed water temperature higher by a predetermined temperature than the hot water supply set temperature is instructed, and when the mixed water temperature detected by the mixed water temperature detection means becomes a temperature higher by a predetermined temperature than the hot water supply set temperature Thereafter, the temperature applied to the hot water supply set temperature is gradually reduced to zero.

Also in this invention, when the temperature of the mixed water downstream from the mixing unit is equal to or lower than the first predetermined temperature, it is determined that the cold start has occurred. If the hot water temperature upstream from the mixing unit is equal to or higher than the second predetermined temperature, it is determined that hot water can be supplied without heating by using the hot water in the hot water storage tank. When it is a cold start and hot water is supplied without using the hot water in the hot water tank, the mixing water temperature is instructed to the mixing unit by a predetermined temperature higher than the hot water supply set temperature. During a cold start that is not heated by the heater, the temperature of the hot water supply pipe can be increased by adjusting the temperature at a temperature higher than the hot water supply set temperature by the mixing unit. If the temperature in the hot water supply pipe rises quickly, the heat dissipation loss when the mixed water passes through the hot water supply pipe is suppressed, so that the rising speed of the hot water temperature supplied from the hot water tap can be increased. It is possible to shorten the rise time at the cold start when the heater is not heated.
In the present invention, after the mixed water temperature detected by the mixed water temperature detecting means becomes a temperature higher than the hot water supply set temperature by a predetermined temperature, the temperature applied to the hot water supply set temperature is gradually reduced to zero.
If the temperature of the mixed water mixed in the mixing unit reaches a temperature that is higher than the preset hot water supply temperature by a predetermined temperature, the temperature in the pipe downstream from the mixing unit also increases. Therefore, even if the temperature of the mixed water sent out from the mixing unit is gradually lowered after this time, the time for the hot water temperature to be supplied at the hot water supply point to rise to the hot water supply set temperature is not lengthened. Since the temperature of the mixed water sent out from the mixing unit is gradually lowered, it is possible to prevent the temperature of the hot water supplied from the hot water tap from fluctuating rapidly.

In the hot water supply system of the present invention, it is preferable that the temperature added to the hot water supply set temperature at the cold start is determined by the temperature difference between the hot water supply set temperature and the mixed water temperature detected by the mixed water temperature detecting means.
When the temperature on the downstream side of the mixing unit is not so low and the rising speed of the temperature in the pipe downstream from the mixing unit is too high, hot water having a temperature higher than the hot water supply set temperature may be supplied. On the other hand, when the temperature on the downstream side is considerably low, if the rising speed of the temperature in the pipe downstream from the mixing unit is too slow, the rise time may take a long time. The temperature added to the hot water supply set temperature is decreased as the downstream temperature is higher, and the temperature added to the hot water set temperature is increased as the downstream temperature is lower, thereby appropriately adjusting the rate of increase in the temperature in the pipe downstream from the mixing unit. It is possible to suppress the change in the hot water supply temperature while shortening the time required for starting up.

Hereinafter, preferred embodiments of the present invention will be described.
(Mode 1) A cold start occurs when both the temperature detected by the sensor installed downstream of the mixing unit and the temperature detected by the sensor installed downstream of the water heater are equal to or lower than the first predetermined temperature. Is determined.
(Mode 2) The second predetermined temperature is a temperature that is higher than the preset hot water supply temperature by a predetermined temperature.
(Mode 3) A multi-stage temperature range is set for the mixed water temperature, and the temperature to be added to the hot water supply set temperature is set stepwise for each temperature range of the mixed water temperature.
(Mode 4) The predetermined integrated flow rate is a pipe capacity (switching preparation flow rate) downstream from the mixing unit.
(Mode 5) The temperature applied to the hot water supply set temperature is decreased stepwise so that the temperature applied to the hot water supply set temperature becomes zero when the integrated flow rate reaches the switching preparation flow rate.

Example 1
A first 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, so that 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, hot water is sucked out 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. In the burner heat exchanger 52, 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 76b 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 the 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 according to the present embodiment, water is heated and stored using the generated heat generated during power generation in the power generation unit 110, and the stored hot water can be used when necessary. When the hot water is not stored or when the temperature of the stored hot water is low, the hot water is heated by the burners 56 and 60 of the water heater 22 and used.
The temperature of the piping of the hot water supply path and the hot water in the piping after the hot water supply stops decreases with time. If a certain amount of time elapses before the next hot water supply, the temperature will drop, and even if hot water is resumed, the hot water adjusted to the hot water supply temperature will not come out immediately, and low-temperature water will come out (called cold start). .
In this specification, the state from the start of hot water supply until the hot water adjusted to the hot water set temperature is supplied is referred to as “rise”, and the hot water adjusted to the hot water set temperature is supplied. This is sometimes called “getting up”.

  When the tap water is heated by the burner 56 of the water heater 22 to supply hot water, the pipe from the downstream side of the burner heat exchanger 52 to the hot water tap 64 before the hot water heated by the burner 56 is discharged at the cold start. A volume of low-temperature water is discharged. Moreover, while the hot water heated by the burner 56 passes through the hot water supply pipe, heat is taken away by the cold hot water supply pipe and the temperature is lowered. Accordingly, even after the low-temperature water corresponding to the pipe capacity from the downstream side of the burner heat exchanger 52 to the hot water tap 64 is discharged, the hot water having a temperature less than the hot water supply set temperature remains until the temperature of the hot water supply pipe rises. Take a bath. This cold start phenomenon is accepted by the user, and the amount of low-temperature water that flows out before hot water adjusted to the hot water supply set temperature is supplied (before starting up) and the time required to start up (also called rise time) ) Has been approved by the user to some extent.

  When hot water is supplied without using the hot water in the hot water storage tank 20 without being heated by the burner 56, that is, when hot water is supplied using heat storage, before the mixed water adjusted by the mixing unit 24 is discharged at the cold start. In addition, low-temperature water corresponding to the piping capacity from the hot water storage tank 20 to the hot-water tap 64 flows out. The amount of low-temperature water discharged at this time is larger by the piping capacity from the hot water storage tank 20 to the downstream side of the burner heat exchanger 52 than when hot water is supplied using the hot water heater 22. In addition, the hot water supply path of the mixed water after temperature adjustment is from the downstream side of the burner heat exchanger 52 to the hot water tap 64 when hot water is supplied using the hot water heater 22, whereas hot water is supplied using heat storage. In this case, from the mixing unit 22 to the hot water tap 64. The hot water supply path of the mixed water after temperature adjustment is equal to the pipe length from the mixing unit 22 to the downstream side of the burner heat exchanger 52, compared with the case where hot water is supplied using heat storage, compared to the case where hot water is supplied using a water heater. Just long. Further, there is a burner heat exchanger 52 between the mixing unit 22 and the hot water tap 64, and low-temperature water stays in the burner heat exchanger 52. Compared to the case where hot water is supplied using heat storage, compared to the case where hot water is supplied using hot water heater 22, the amount of heat lost to low temperature water staying in the hot water supply pipe or the burner heat exchanger 52 that is cooled at the cold start is less. Increased heat dissipation loss.

  In the cogeneration system of the present embodiment, a bypass pipe 37 that bypasses the burner heat exchanger 52 is formed in a hot water path 51 that is a hot water supply path, and a bypass servo 38 is provided in the bypass pipe 37. If the hot water heater 22 is not used, the opening of the bypass servo 38 is adjusted, the bypass pipe 37 side is fully opened, and the burner heat exchanger 52 side is fully closed. Heat is not lost to the low-temperature water staying in the exchanger 52. However, if the burner 56 is ignited in the state where the burner heat exchanger 52 side is fully closed, the burner heat exchanger 52 part will be in an empty state. For this reason, in the cogeneration system of the present embodiment, the control for fully closing the burner heat exchanger 52 side is not performed in consideration of safety.

In the cogeneration system of the present embodiment, the rise time at the cold start when the hot water is supplied using the heat storage is shortened by performing the hot water supply temperature control as follows.
As shown in FIG. 2, it is determined in step S10 whether the flow rate detected by the second flow rate sensor 47 is 2.7 liters / min or more. When the flow rate detected by the second flow rate sensor 47 is 2.7 liters / min or more (YES in step S10), it is considered that there is a hot water supply request, and the process proceeds to step S12. In step S12, integration of the flow rate detected by the second flow rate sensor 47 is started.
In step S14, it is determined whether or not the temperature detected by the mixed water thermistor 54 on the downstream side of the mixing unit 24 is 25 ° C. or less. If the detected temperature of the mixed water thermistor is 25 ° C. or less (if YES in step S14), the process proceeds to step S16, and whether the temperature detected by the hot water supply thermistor 65 on the downstream side of the burner heat exchanger 52 is 25 ° C. or less. It is determined whether or not. If the detected temperature of the hot water supply thermistor is 25 ° C. or lower (YES in step S16), the process proceeds to step S18. When both the detected temperature of the mixed water thermistor and the detected temperature of the hot water supply thermistor are 25 ° C. or less, it is regarded as a cold start and the process proceeds to step S18.

At a cold start, the lower the temperature of hot water in the hot water supply pipe and the hot water supply pipe downstream from the mixing unit 24, the more heat is taken away by the cold hot water supply pipe. It takes time to get hot water. In the case of hot water supply using heat storage, this phenomenon becomes particularly remarkable because the hot water supply path is long from the hot water storage tank 20 to the hot water tap 64.
In the present embodiment, when hot water is supplied using heat storage, the temperature of the mixed water adjusted by the mixing unit 24 is increased by a temperature α, thereby quickly increasing the temperature of the piping of the hot water supply path and shortening the rise time. To do. In step S18, the temperature α is determined. The temperature α is determined by the detected temperature of the mixed water thermistor 54. The temperature is divided into three stages according to the temperature of hot water in the hot water supply pipe downstream from the mixing unit 24, and the temperature α is set higher in the lower temperature range. If the detected temperature of the mixed water thermistor 54 is 5 ° C. or less, α is set to 15 ° C. If the detected temperature of the mixed water thermistor 54 exceeds 5 ° C. and is 15 ° C. or less, α is set to 10 ° C. If the detected temperature of the mixed water thermistor 54 exceeds 15 ° C. and is 25 ° C. or less, α is set to 5 ° C. By increasing the temperature α when the hot water temperature in the hot water supply pipe is low, the temperature of the cold hot water supply pipe can be increased more quickly. By reducing the temperature α when the hot water temperature in the hot water supply pipe is not very low, the temperature rise rate in the hot water supply pipe is too high, and the temperature control in the mixing unit 24 is delayed, resulting in a temperature higher than the hot water supply temperature. It is possible to prevent the mixed water from being supplied with hot water.

It progresses to step S20 and it is discriminate | determined whether the temperature which the upper thermistor 35 for detecting the hot water temperature of the upper part of the hot water storage tank 20 detects is more than the temperature which added (alpha) +1 degreeC to hot water supply preset temperature. At this time, + 1 ° C. is taken into consideration of heat radiation. If the detected temperature of upper thermistor 35 is equal to or higher than [hot water supply set temperature + α + 1 ° C.] (YES in step S20), it is considered that the hot water in hot water tank 20 can be used for hot water supply, and the process proceeds to step S22. In Step S22, in the mixing unit 24, the opening degree of the hot water inlet 24c and the opening degree of the water supply inlet 24a are controlled so that the detected temperature of the mixed water thermistor 54 becomes [hot water supply set temperature + α].
In step S24, it is determined whether or not the integrated flow rate detected by the second flow rate sensor 47 has reached the switching preparation flow rate. The switching preparation flow rate is a pipe capacity from the mixed water thermistor 54 on the downstream side of the mixing unit 24 to the hot water supply thermistor 65 on the downstream side of the burner heat exchanger 52. When the integrated flow rate detected by the second flow rate sensor 47 reaches the switching preparation flow rate (if YES in step S24), the mixed water adjusted to [hot water supply set temperature + α] by the mixing unit 24 is supplied to the hot water supply thermistor 65. It is considered that it has reached, and the process proceeds to step S28. Even if the integrated flow rate detected by the second flow rate sensor 47 does not reach the switching preparation flow rate (NO in step S24), the detected temperature of the hot water supply thermistor 65 reaches the hot water supply set temperature in step S26. If yes (YES), the process proceeds to step S28. In step S28, the mixing unit 24 supplies hot water by controlling the opening of the hot water inlet 24c and the opening of the water supply inlet 24a so that the detected temperature of the mixed water thermistor 54 becomes the hot water supply set temperature. Thereafter, in step S30, the detected temperature of the mixed water thermistor 54 is maintained until the flow rate detected by the second flow sensor 47 becomes 2.0 liters / min or less (becomes YES) and the hot water supply is regarded as being stopped. The mixed water adjusted to have a set temperature is supplied with hot water.

  In step S20, if the detected temperature of the upper thermistor 35 is lower than [hot water supply set temperature + α + 1 ° C.] (if NO), it is considered that the hot water temperature in the hot water storage tank 20 is low and cannot be used for hot water supply, Hot water supply using the water heater 22 is performed. In step S32, the burner 56 is ignited, and in step S34, the temperature of the hot water supply thermistor 65 is adjusted so as to become the hot water supply set temperature, and hot water is supplied. Thereafter, in step S30, the detected temperature of the hot water supply thermistor 65 is set to the hot water supply until the flow rate detected by the second flow sensor 47 becomes 2.0 liters / min or less (becomes YES) and the hot water supply is considered to be stopped. Hot water adjusted to a temperature is supplied.

  If the detected temperature of the mixed water thermistor 54 is higher than 25 ° C. in step S14 (NO), or if the detected temperature of the hot water supply thermistor 65 is higher than 25 ° C. in step S16 (if NO), the piping The internal temperature is high, and it is considered that there is no need to adjust the temperature at a temperature higher by the temperature α when adjusting the temperature in the mixing unit 24. Therefore, it progresses to step S36 and it is discriminate | determined whether the temperature which the upper thermistor 35 detects is more than the temperature which added 1 degreeC to the hot water supply preset temperature. If the detected temperature of upper thermistor 35 is equal to or higher than [hot water supply set temperature + 1 ° C.] (YES in step S36), it is considered that the hot water in hot water tank 20 can be used for hot water supply, and the process proceeds to step S38. In step S38, the mixing unit 24 supplies hot water by controlling the opening of the hot water inlet 24c and the opening of the water supply inlet 24a so that the detected temperature of the mixed water thermistor 54 becomes the hot water supply set temperature. Thereafter, in step S30, the detected temperature of the mixed water thermistor 54 is maintained until the flow rate detected by the second flow sensor 47 becomes 2.0 liters / min or less (becomes YES) and the hot water supply is regarded as being stopped. The mixed water adjusted to have a set temperature is supplied with hot water.

  If the detected temperature of the upper thermistor 35 falls below [hot water supply set temperature + 1 ° C.] (if NO) in step S36, it is considered that the hot water temperature in the hot water storage tank 20 is low and cannot be used for hot water supply. Hot water supply using the vessel 22 is performed. In step S32, the burner 56 is ignited, and in step S34, the temperature of the hot water supply thermistor 65 is adjusted so as to become the hot water supply set temperature, and hot water is supplied. Thereafter, in step S30, the detected temperature of the hot water supply thermistor 65 is set to the hot water supply until the flow rate detected by the second flow sensor 47 becomes 2.0 liters / min or less (becomes YES) and the hot water supply is considered to be stopped. Hot water adjusted to a temperature is supplied.

The graph of FIG. 6 shows the transition of the mixed water temperature (shown by a broken line) and the hot water supply temperature (shown by a solid line) when the temperature is adjusted at the hot water supply set temperature in the mixing unit 24 at the cold start, The graph of FIG. 3 shows the transition of the mixed water temperature (shown by a broken line) and the hot water supply temperature (shown by a solid line) when the hot water temperature control process of FIG. 2 is performed in the cogeneration system of the present embodiment. Since the hot water supply thermistor 65 is located downstream of the mixed water thermistor 54, the temperature rise of the temperature detected by the hot water supply thermistor 65 (hot water supply temperature) is delayed from the temperature rise of the temperature detected by the mixed water thermistor 54 (mixed water temperature). Happens.
As shown in FIG. 6, when the mixing unit 24 adjusts the temperature at the hot water supply set temperature, the mixed water temperature at the start of the hot water supply rises rapidly, but the hot water temperature supplied from the hot water tap 64 depends on the mixing unit 24 and the hot water supply. Heat is taken away by the hot water supply pipe between the plug 64 and the low-temperature water or the like staying in the burner heat exchanger 52, and the temperature rise stagnates as shown in FIG. Even if the mixed water temperature is the hot water supply set temperature, the hot water supply temperature does not readily rise to the hot water supply set temperature, and the rise time becomes longer and the usability is poor.

  The time t1 shown in FIG. 3 indicates the time when hot water supply is started and the integration of the flow rate detected by the second flow rate sensor 47 is started (step S12 in FIG. 2), and the time t2 is the second flow rate sensor. This shows the time when the integrated flow rate of the detected flow rate of 47 has reached the switching preparation flow rate (YES in step S24). As shown in FIG. 3, in the hot water temperature control process of FIG. 2, the temperature of the mixed water in the mixing unit 24 at the start of hot water supply (time t1) is made higher by the temperature α than the hot water supply set temperature (in FIG. For the sake of clarity, the illustration of + 1 ° C. considering heat dissipation is omitted). Therefore, the rising speed of the temperature in the piping of the hot water supply path can be increased. If the temperature in the hot water supply pipe rises quickly, the heat dissipation loss when the mixed water passes through the hot water supply pipe is suppressed, so that the rising speed of the temperature of the mixed water supplied with hot water can be increased. When the integrated flow rate detected by the second flow rate sensor 47 reaches the switching preparation flow rate (time t2), the temperature of the mixed water adjusted by the mixing unit 24 is lowered to the hot water supply set temperature, whereby the hot water supply temperature is changed to the hot water supply set temperature. To prevent the temperature from rising. At this time, the temperature in the hot water supply pipe has already increased, and the temperature in the burner heat exchanger 52 has also increased. For this reason, even if the mixed water temperature adjusted by the mixing unit 24 at the time t2 is switched to the hot water supply set temperature, the temperature increase of the hot water supply temperature is not hindered.

  According to the cogeneration system of this embodiment, even when the hot water supply pipe is cold at the cold start and the hot water supply path is long and the heat dissipation loss is large to supply hot water using heat storage, Time can be shortened and usability can be improved.

(Example 2)
A second embodiment embodying the present invention will be described with reference to the drawings. The configuration of the cogeneration system of the present embodiment is the same as the configuration of the cogeneration system of the first embodiment. In the present embodiment, similarly to the first embodiment, the mixed water temperature adjusted by the mixing unit 24 is set higher than the hot water supply set temperature, thereby shortening the rise time at the cold start. However, this embodiment differs from the first embodiment in part of the hot water temperature control. Here, the description of the same parts as those in the first embodiment is omitted, and only different parts will be described.

In the hot water supply temperature control of the cogeneration system of the present embodiment shown in FIG. 4, the processing from step S110 to step S122 is the processing from step S10 to step S22 of the first embodiment described above with reference to FIG. Since it is the same as that of FIG.
In step S122, the temperature of the mixed water thermistor 54 is adjusted to gradually increase. If the detected temperature of the mixed water thermistor 54 reaches [hot water supply set temperature + α ° C.] in step S123 (if YES), Proceed to step S124.

In step S124, the temperature α decreases as the integrated flow rate detected by the second flow sensor 47 approaches the switching preparation flow rate, and when the integrated flow rate detected by the second flow sensor 47 reaches the switching preparation flow rate, the temperature α Becomes 0 ° C. As the integrated flow rate detected by the second flow sensor 47 approaches the switching preparation flow rate, the detected temperature of the mixed water thermistor 54 gradually decreases, and the integrated flow rate detected by the second flow sensor 47 reaches the switching preparation flow rate. At this time, the detected temperature of the mixed water thermistor 54 becomes the hot water supply set temperature.
In step S125, it is determined whether or not the integrated flow rate detected by the second flow rate sensor 47 has reached the switching preparation flow rate. When the integrated flow rate detected by the second flow rate sensor 47 reaches the switching preparation flow rate (YES in step S125), the mixed water whose temperature is adjusted to [hot water supply set temperature + α] by the mixing unit 24 is the hot water supply thermistor. It is considered that 65 has been reached, and the process proceeds to step S128. Even if the integrated flow rate detected by the second flow rate sensor 47 does not reach the switching preparation flow rate in step S125 (even if NO), the detected temperature of the hot water supply thermistor 65 reaches the hot water supply set temperature in step S126. If yes (YES), the process proceeds to step S128. In step S128, the mixing unit 24 supplies hot water by controlling the opening of the hot water inlet 24c and the opening of the water supply inlet 24a so that the detected temperature of the mixed water thermistor 54 becomes the hot water supply set temperature. Thereafter, in step S130, the detected temperature of the mixed water thermistor 54 is maintained until the flow rate detected by the second flow sensor 47 becomes 2.0 liters / min or less (becomes YES) and the hot water supply is regarded as being stopped. The mixed water adjusted to have a set temperature is supplied with hot water.

  The time t1 shown in FIG. 5 indicates the time when hot water supply is started and the integration of the flow rate detected by the second flow rate sensor 47 is started (step S112 in FIG. 4), and the time t2 is the second flow rate sensor. This shows the time when the integrated flow rate of the detected flow rate of 47 has reached the switching preparation flow rate (YES in step S125). Time t3 indicates the time when the detected temperature of the mixed water thermistor 54 reaches [hot water supply set temperature + α] (YES in step S123 in FIG. 4). As shown in FIG. 5, in the hot water temperature control process of FIG. 4, similarly to the hot water temperature control process of FIG. 2, the mixed water temperature adjusted by the mixing unit 24 at the start of hot water supply (time t1) is set as the hot water supply set temperature. The temperature is higher by α (in FIG. 5, illustration of + 1 ° C. in consideration of heat radiation is omitted for clarity of illustration). Therefore, the rising speed of the temperature in the piping of the hot water supply path can be increased. When the detected temperature of the mixed water thermistor 54 reaches [hot water supply set temperature + α] (time t3), the temperature of the mixed water adjusted by the mixing unit 24 starts to gradually decrease, and the detected flow rate of the second flow rate sensor 47 is integrated. When the flow rate reaches the switching preparation flow rate (time t2), the temperature is lowered so that the temperature of the mixed water adjusted by the mixing unit 24 is exactly the hot water supply set temperature. This prevents the hot water supply temperature from rising beyond the hot water supply set temperature. In addition, as in the first embodiment, the hot water supply temperature can be stabilized as compared to reducing the temperature of the mixed water adjusted by the mixing unit 24 at a time t2 at a time t2. At time t3, the temperature in the hot water supply pipe has already increased, and the temperature in the burner heat exchanger 52 has also increased. For this reason, even if the mixed water temperature controlled by the mixing unit 24 is gradually lowered to the hot water supply set temperature from time t3 to time t2, the temperature rise of the hot water supply temperature after time t3 is not delayed.

  According to the cogeneration system of this embodiment, even when the hot water supply pipe is cold at the cold start and the hot water supply path is long and the heat dissipation loss is large to supply hot water using heat storage, Time can be shortened and the hot water supply temperature can be stabilized.

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 systematic diagram of the cogeneration system which concerns on 1st Example. The flowchart which shows the hot water supply temperature control process at the time of the hot water supply start in 1st Example. The graph which shows the change of the mixed water temperature and hot water supply temperature in 1st Example. The flowchart which shows the hot water supply temperature control process at the time of the hot water supply start in 2nd Example. The graph which shows the change of the mixed water temperature and hot water supply temperature in 2nd Example. The graph which shows the change of the mixed water temperature and hot water supply temperature in a prior art example.

Explanation of symbols

10: Hot water supply system 20: Hot water storage tank 22: Water heater 24: Mixing unit 35: Upper thermistor 47: Second flow sensor 54: Mixed water thermistor 65: Hot water thermistor 110: Power generation unit

Claims (3)

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;
Hot water temperature detection 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 temperature indicating means for instructing the mixing unit of the mixed water temperature;
Provided with a mixed water flow rate integrating means for integrating the mixed water flow rate after the start of the mixed water flow,
The mixed water temperature indicating means is such that the mixed water temperature detected by the mixed water temperature detecting means is not higher than a first predetermined temperature, the hot water temperature detected by the hot water temperature detecting means is not lower than a second predetermined temperature, When the integrated flow integrated by the mixed water flow integration means is less than or equal to the predetermined integrated flow, a mixed water temperature higher than the hot water set temperature by a predetermined temperature is indicated, and when the integrated flow is equal to or higher than the predetermined integrated flow, A hot water supply system characterized by indicating a temperature. 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;
Hot water temperature detection 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;
Comprising a mixed water temperature control means to direct the mixed water temperature to the mixing unit,
When the mixed water temperature detected by the mixed water temperature detecting means is not higher than a first predetermined temperature and the hot water temperature detected by the hot water temperature detecting means is not lower than a second predetermined temperature, A mixed water temperature that is higher by a predetermined temperature than the hot water supply set temperature is instructed, and after the mixed water temperature detected by the mixed water temperature detection means becomes a temperature that is higher than the hot water supply set temperature by a predetermined temperature, the hot water supply set temperature is set. A hot water supply system characterized in that the predetermined temperature to be applied is gradually reduced to zero.   3. The hot water supply system according to claim 1, wherein the predetermined temperature to be added to the hot water supply set temperature is determined by a temperature difference between the hot water supply set temperature and the mixed water temperature detected by the mixed water temperature detecting means.

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