JP5901312B2 - Hot water storage system - Google Patents

Description

  The present invention relates to a hot water storage system that recovers heat from a heat source such as a fuel cell (a gas engine generator, a fuel processing device (reformer), etc.) to heat and supply hot water in a hot water storage tank. The present invention relates to a hot water storage system that supplies hot water by supplementing the shortage with a backup heat source machine when heat storage is insufficient.

  FIG. 12 shows a configuration example of a conventional hot water storage system 100 that uses exhaust heat of a fuel cell. The hot water storage system 100 includes a hot water storage tank unit 101, an exhaust heat recovery device 110 that recovers exhaust heat of the fuel cell 130, and a gas water heater 120 as a backup heat source unit. The exhaust heat recovery device 110 includes an exhaust heat recovery heat exchanger 111 and an exhaust heat recovery pump 112.

  A water supply pipe 104 is connected to the lower water supply port 103 of the hot water storage tank 102, and a hot water discharge pipe 106 is connected to the upper hot water outlet 105. A mixer 107 that mixes hot water from the hot water storage tank 102 and water from the water supply pipe 104 at a set mixing ratio is provided in the middle of the hot water discharge pipe 106, and the outlet side of the mixer 107 is connected to a connecting pipe 121. And is connected to the water supply connection port 122 of the gas water heater 120.

  The gas water heater 120 includes a heat exchanger 123 and a first burner 124 that heat water supplied (or hot water) flowing from the water supply connection port 122 when hot water is supplied or poured into a bathtub.

  In the hot water storage system 100 configured as described above, the exhaust heat recovery pump 112 is operated when the exhaust heat of the fuel cell 130 is recovered and the hot water in the hot water storage tank 102 is heated. Thus, the hot water in the hot water storage tank 102 passes from the lower part of the hot water storage tank 102 to the upper part of the hot water storage tank 102 via the heat recovery pipe (low temperature) 114, the exhaust heat recovery heat exchanger 111, and the heat recovery pipe (high temperature) 115. It circulates in the return path and is heated as it passes through the exhaust heat recovery heat exchanger 111.

  In the hot water supply operation, when the hot water storage tank 102 has sufficiently stored heat, the hot water and hot water in the hot water storage tank 102 are mixed by the mixer 107 to produce hot water at a set temperature, and the hot water is supplied to the gas water heater 120. 120 does not perform additional heating and supplies hot water as it is. Further, when there is no heat storage in the hot water storage tank 102, hot water or water having a temperature lower than the set temperature in the hot water storage tank 102 is sent to the gas water heater 120 and heated to the set temperature by the gas water heater 120 to supply hot water. If the hot water in the hot water storage tank 102 is slightly lower than the set temperature and is sent to the gas water heater 120 as it is, the hot water temperature will exceed the set temperature even if the gas water heater 120 is operated with the minimum capacity. Then, the hot water from the hot water storage tank 102 is mixed with the hot water and the temperature is intentionally lowered to the gas water heater 120, and the gas water heater 120 is heated to the set temperature to supply the hot water.

JP 2010-236713 A JP 2007-10244 A Japanese Patent No. 4559307 Japanese Patent No. 3935416

  A hot water storage tank unit and a heat source such as a fuel cell are often provided separately from each other, and a heat recovery pipe connecting them is provided outdoors. Therefore, in a cold region, the heat recovery pipe may freeze while the operation of the combustion battery 130 is stopped. As countermeasures against freezing, for example, a heater is wound around the heat recovery pipe at the time of construction, or a heating device such as an electric heater provided in the fuel cell unit while operating the exhaust heat recovery pump in the fuel cell unit. A method of circulating and heating water is assumed. However, in these methods, the number of work steps at the time of construction increases and a heater or the like is added, resulting in an increase in system cost.

  An object of the present invention is to provide a hot water storage system capable of preventing the heat recovery pipe from being frozen without winding a heater around the pipe.

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] A hot water storage tank to which water is supplied and a heating device that recovers heat from a predetermined heat source and heats the water in the hot water storage tank, and the heat storage in the hot water storage tank is insufficient for the hot water at a set temperature. A hot water storage system that uses a backup heat source to heat the shortage
The heating device includes a heat exchanger for recovering heat from the heat source, a forward heat recovery pipe from the hot water storage tank to the inlet side of the heat exchanger, and an outlet side of the heat exchanger to the hot water storage tank. A return heat recovery pipe, and a heat recovery pump for circulating hot water in a heat recovery circulation path that returns from the hot water storage tank to the forward heat recovery pipe, the heat exchanger, and the return heat recovery pipe to the hot water storage tank. Configured
Furthermore, a path changing unit that switches the heat recovery circulation path to a bypass circulation path that bypasses the hot water storage tank;
A branch pipe connected to the hot water outlet of the backup heat source machine, branched from the first pipe leading to the hot water tap, and joined to the return heat recovery pipe of the portion constituting the bypass circulation path;
A merging pipe that branches from the forward heat recovery pipe of the part that forms the detour circulation path and joins to a second pipe that leads to a water supply port of the backup heat source unit;
A circulation pump that is provided in the junction pipe and feeds water toward the second pipe;
A control unit;
With
The controller is
When recovering the heat of the heat source to heat the water in the hot water storage tank, the heat recovery pump is operated to circulate the water in the hot water storage tank to the heat recovery circulation path,
When supplying heat to the heat recovery pipe, the heat recovery circulation path is switched to the bypass circulation path, the heat recovery pump and the circulation pump are operated, and further controlled to be heated by the backup heat source machine. ,
When the hot water supply port supplies heat to the heat recovery pipe, it does not switch between the state where the hot water supply port is connected to the branch pipe and the state where the hot water supply port is connected to the first pipe ahead of the branch point of the branch pipe. A hot water storage system in which a hot water supply port of a heat source device is in a state of communicating with both the branch pipe and the first pipe ahead of the branching point of the branch pipe .

In the above invention, the heat recovery circulation path connecting the hot water storage tank and the exhaust heat recovery device is branched from the path changing unit that switches to the bypass circulation path bypassing the hot water storage tank, and the return heat recovery pipe of the bypass circulation path. Branch path that returns to the detour circulation path via the backup heat source machine (path that branches from the forward heat recovery pipe, returns to the heat recovery pipe via the merge pipe, second pipe, backup heat source machine, first pipe, and branch pipe) And a circulation pump for circulating hot water in the branch path. When supplying heat to the heat recovery pipe to prevent freezing, switch the heat recovery circulation path to a bypass circulation path bypassing the hot water storage tank, and operate the heat recovery pump and circulation pump of the exhaust heat recovery device Then, heat with a backup heat source machine. As a result, part of the water circulating in the detour circulation path flows to the branch path side, is heated by the backup heat source unit, and returns to the detour circulation path, the water temperature in the detour circulation path rises, and freezing occurs. Is prevented.
[2] The branch pipe is provided with a check valve for preventing the flow from the return heat recovery pipe side to the first pipe side.
The hot water storage system according to [1].

[ 3 ] The apparatus further comprises a mixer for mixing hot water from the hot water supply port of the backup heat source unit flowing in through the first pipe, hot water from the hot water storage tank, and hot water at a set mixing ratio to supply hot water. ,
Water is supplied to the water supply port of the backup heat source machine through the second pipe,
The control unit controls heating by the backup heat source unit and a mixing ratio of the mixer so that hot water having a set temperature is supplied from the mixer. [1] or [2] Hot water storage system.

  In the said invention, the system (post-mixing system) which mixes the hot water from a backup heat source machine, the hot water from a hot water storage tank, and the feed water from a water supply pipe with a mixer, and supplies hot water of a preset temperature is employ | adopted.

[ 4 ] A mixer in which hot water and water supply from the hot water outlet of the hot water storage tank are mixed at a set mixing ratio, and the second pipe leading to the water supply port of the backup heat source machine is further connected to the outlet side. Have
The control unit controls the mixing ratio of the mixer so that hot water at a set temperature is supplied from the backup heat source unit without additional heating by the backup heat source unit or by adding heating by the backup heat source unit. The hot water storage system according to [1] or [2], which is characterized.

  In the above invention, a hot water supply (hot water preheating method) is used in which hot water from a hot water storage tank and hot water from a water supply pipe are mixed in a mixer and sent to a backup heat source machine, and the shortage is heated by the backup heat source machine. doing.

[ 5 ] The path changing unit switches the heat recovery circulation path to the bypass circulation path when the temperature of hot water flowing from the return heat recovery piping side is lower than a predetermined temperature. The hot water storage system according to any one of 5 ].

  In the above-mentioned invention, only hot water sufficiently heated by heat recovery or a backup heat source device is returned to the hot water storage tank, and water or hot water with insufficient heating is prevented from returning to the hot water storage tank. In addition, at the temperature of the hot water heated to the extent that freezing prevention is possible, the path changing unit becomes a bypass circulation path.

  According to the hot water storage system according to the present invention, freezing of the heat recovery pipe can be prevented without winding a heater around the pipe.

It is a figure which shows the structure of the bath hot-water supply system which concerns on the 1st Embodiment of this invention. It is a figure which shows schematic structure of a bath water heater. It is explanatory drawing which shows the flow of the hot water in the waste heat recovery operation | movement of the bath hot-water supply system which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the flow of the hot water in the hot water supply operation | movement of the bath hot water system which concerns on 1st Embodiment. It is explanatory drawing which shows the flow of the hot water in the freeze prevention operation | movement of the heat recovery piping of the bath hot-water supply system which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the bath hot-water supply system which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the flow of the hot water in the waste heat recovery operation | movement of the bath hot-water supply system which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the flow of the hot water in the hot water supply operation of the 1st mode of the bath hot water system which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the flow of the hot water in the hot water supply operation | movement of the 2nd mode of the bath hot-water supply system which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the flow of the hot water in the hot water supply operation | movement of the 3rd mode of the bath hot-water supply system which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the flow of the hot water in the freeze prevention operation | movement of the heat recovery piping of the bath hot-water supply system which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of schematic structure of the conventional hot water storage system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The basic concept of the present invention will be described.

  A hot water storage system according to the present invention includes a path changing unit that switches a heat recovery circulation path connecting a hot water storage tank and an exhaust heat recovery device to a bypass circulation path that bypasses the hot water storage tank, and a branch from the middle of the bypass circulation path. A branch path returning to the detour circulation path via the backup heat source unit and a circulation pump for circulating hot water in the branch path are provided. In order to prevent the heat recovery pipe from freezing, the heat recovery circulation path is switched to a bypass circulation path, the heat recovery pump and the circulation pump of the exhaust heat recovery apparatus are operated, and further heated by a backup heat source machine. As a result, a part of the water circulating in the detour circulation path flows to the branch path side, is heated by the backup heat source machine, and returns to the detour circulation path, and the water temperature in the detour circulation path is raised and frozen. Is prevented.

  Hereinafter, a first embodiment in which the anti-freezing technology of the present invention is applied to a hot water storage system using a feed water preheating system and a second embodiment in which the technique is applied to a hot water storage system using a post-mixing system will be described.

  First, a first embodiment of the present invention will be described.

  FIG. 1 shows a configuration of a bath hot water supply system 10 according to a first embodiment to which a hot water storage system of the present invention is applied. The bath hot water supply system 10 includes a hot water storage tank unit 11, a heat source unit 4, an exhaust heat recovery device 50 that recovers exhaust heat from the heat source unit 4, and a bath water heater 70 as a backup heat source unit. The bath hot water supply system 10 sends hot water obtained by mixing hot water from the hot water storage tank 13 and water supplied from the water supply pipe 12 in the mixer 23 to the bath water heater 70, and supplies the hot water by heating the shortage in the bath water heater 70. Preheating method is adopted. In the figure, piping between apparatuses and external piping are indicated by double arrows. In this example, a fuel cell is used as the heat source unit 4.

  The hot water storage tank unit 11 includes a hot water storage tank 13 that stores water supplied from a water supply pipe 12. The hot water storage tank 13 is a hollow, substantially cylindrical tank, with a water supply port 14 provided at the lower part and a hot water outlet 15 provided at the upper part. Further, a water intake port 16 is provided at the lower part of the hot water storage tank 13 and a return port 17 is provided at the upper part.

  The hot water storage tank 13 has, for example, a capacity of about 100 liters, and a first temperature sensor 18a for detecting the water temperature at the water level of 20 liters from the bottom has a water level of 40 liters from the bottom. A second temperature sensor 18b for detecting the water temperature at the location is located at a location where the water level is 60 liters from the bottom, and a third temperature sensor 18c for detecting the water temperature at the location is located at a location where the water level is 80 liters from the bottom. A hot water temperature sensor 18d for detecting the water temperature is further provided, and a tank upper temperature sensor 18e for detecting the water temperature at the location is provided at the uppermost part of the hot water storage tank 13, respectively.

  The exhaust heat recovery device 50 is provided in the heat source unit 4 or the like and recovers the exhaust heat of the heat source unit 4. The exhaust heat recovery device 50 includes an exhaust heat recovery heat exchanger 51 and an exhaust heat recovery pump 52. The heat recovery pipe 53 (53a, 53b) is configured so that a heat recovery circulation path for circulating water in the hot water storage tank 13 is configured between the hot water storage tank 13 and the exhaust heat recovery heat exchanger 51 of the exhaust heat recovery apparatus 50. Connected with. Specifically, one end of a heat recovery pipe (low temperature) 53 a is connected to the water intake 16 of the hot water storage tank 13, and the other end of the heat recovery pipe (low temperature) 53 a is connected to the inlet side of the exhaust heat recovery heat exchanger 51. ing. The exhaust heat recovery pump 52 is inserted into a heat recovery pipe (low temperature) 53a in the vicinity of the entrance side of the exhaust heat recovery heat exchanger 51, and the exhaust heat recovery pump 52 uses the water in the heat recovery pipe (low temperature) 53a. Water is fed from the intake 16 side of the hot water storage tank 13 toward the entrance side of the exhaust heat recovery heat exchanger 51.

  One end of a heat recovery pipe (high temperature) 53 b is connected to the outlet side of the exhaust heat recovery heat exchanger 51, and the other end of the heat recovery pipe (high temperature) 53 b is the first one of the first three-way valve 21 in the hot water storage tank unit 11. It is connected to the connection port 21a.

  The first three-way valve 21 includes the first connection port 21a, the second connection port 21b, and the third connection port 21c, and connects the first connection port 21a and the second connection port 21b to form a third connection port. The connection state can be switched between the A direction for closing 21c and the B direction for connecting the first connection port 21a and the third connection port 21c and closing the second connection port 21b. The first three-way valve 21 is controlled by the control unit 20 so as to be in the A direction if the temperature of the water flowing in from the first connection port 21a is equal to or higher than the predetermined temperature, and to be switched to the B direction if the temperature is lower than the predetermined temperature.

  The second connection port 21 b of the first three-way valve 21 is connected to the return port 17 of the hot water storage tank 13. One end of the bypass pipe 54 is connected to the third connection port 21 c of the first three-way valve 21, and the other end of the bypass pipe 54 joins the heat recovery pipe (low temperature) 53 a in the hot water storage tank unit 11.

  A heat recovery pipe high temperature side temperature sensor 22a is provided in the heat recovery pipe (high temperature) 53b in the vicinity of the first connection port 21a of the first three-way valve 21, and a junction between the water intake 16 of the hot water storage tank 13 and the bypass pipe 54 is provided. The heat recovery pipe low temperature side sensor 22b is provided in the heat recovery pipe (low temperature) 53a until the above.

  The hot water storage tank unit 11 includes a mixer 23 that mixes hot water from the hot water outlet 15 of the hot water storage tank 13 and water supply. This mixer 23 is actually a first mixer 23 a that adjusts the amount of hot water supplied from the hot water outlet 15 of the hot water storage tank 13 and a second mixer 23 b that adjusts the amount of mixed water supplied from the water supply pipe 12. And is configured.

  The inlet side of the first mixer 23a is connected to a hot water outlet 15 of the hot water storage tank 13 by piping, and an overpressure relief valve 24, an intake valve 25, and a tank outlet temperature sensor 26 are provided in the middle of the piping. . A water supply pipe 12 is connected to the entrance side of the second mixer 23b.

  The outlet side of the first mixer 23 a and the outlet side of the second mixer 23 b merge to communicate with the outlet of the mixer 23. A connection pipe 61 that leads to a water supply connection port of the bath water heater 70 is connected to the outlet of the mixer 23. The connecting pipe 61 in the vicinity of the outlet side of the mixer 23 is provided with a tapping temperature sensor 32 and a high cut temperature sensor 33.

  The water supply pipe 12 inside the hot water storage tank unit 11 is provided with a flow rate sensor 34, a water supply temperature sensor 35, and a pressure reducing valve 36. The water supply pipe 12 branches into two downstream of these, one of which is connected to the inlet side of the second mixer 23b via a check valve 37a, and the other is connected to the hot water storage tank 13 via the check valve 37b. It is connected to the water supply port 14.

  Further, a drain pipe 41 leading to a predetermined drainage point is connected to the water intake 16 of the hot water storage tank 13, and a drain plug 42 for opening and closing the pipe line is provided in the middle of the drain pipe 41.

  A hot water supply pipe 62 leading to a hot water tap or the like is connected to the hot water supply connection port of the bath water heater 70. Further, the branch pipe 43 branched in the middle of the hot water supply pipe 62 is piped toward the hot water storage tank unit 11 and joined to the heat recovery pipe (high temperature) 53b inside the hot water storage tank unit 11. The branch pipe 43 in the hot water storage tank unit 11 is provided with a check valve 44 for preventing a reverse flow from the return pipe temperature sensor 28 and the heat recovery pipe (high temperature) 53b side.

  In addition, a junction pipe 45 that branches from the heat recovery pipe (low temperature) 53 a and joins to the connection pipe 61 is provided in the hot water storage tank unit 11. In the middle of the merging pipe 45, a circulation pump 46 and a pump solenoid valve 47 for supplying water from the heat recovery pipe (low temperature) 53a to the connection pipe 61 are provided. The pump solenoid valve 47 opens and closes the merge pipe 45. The pump solenoid valve 47 prevents hot water from flowing backward from the connection pipe 61 and flowing into the hot water storage tank 13. Further, the pump solenoid valve 47 prevents water in the lower part of the hot water storage tank 13 from flowing out from the water intake 16 and flowing out to the water supply connection port of the bath water heater 70 through the connection pipe 61 during a hot water supply operation described later.

  The hot water storage tank unit 11 is provided with an atmospheric temperature sensor 49 for measuring the atmospheric temperature (outside air temperature).

  The hot water storage tank unit 11 includes a control unit 20 that performs overall control of the operation of the hot water storage tank unit 11. The control unit 20 includes a CPU (Central Processing Unit), a flash ROM (Read Only Memory) that stores programs executed by the CPU, fixed data, and the like, and a RAM that temporarily stores various types of information when the CPU executes programs. (Random Access Memory) and an I / F (Interface) unit for inputting / outputting various signals and the like. Detection signals from various sensors of the hot water tank unit 11 are input to the control unit 20. A control signal is output from the control unit 20 to each valve and other controlled objects. The control unit 20 further exchanges various information and commands with the heat source unit 4 and the bath water heater 70.

  Next, a configuration example of the bath water heater 70 as a backup heat source device will be described. The bath water heater 70 has a function of heating and discharging water flowing from the water supply connection port, a function of pouring (filling) the bath (tub) 2, and a function of chasing hot water in the bath (tub) 2. This is a gas-fired bath water heater.

  As shown in FIG. 2, the bath water heater 70 includes a one-can two-water channel type heat exchanger 72 through which a first heat exchange water pipe 72 a and a second heat exchange water pipe 72 b pass, and a burner that heats the heat exchanger 72. 73 is provided. A gas supply pipe 73a is connected to the burner 73, and a gas valve for switching supply / cutoff of gas and a proportional valve for adjusting the amount of supply gas are provided in the middle of the gas supply pipe 73a.

  The inlet side of the first heat exchange water pipe 72 a is connected to a water supply connection port by a water inlet pipe 74, and the outlet side of the first heat exchange water pipe 72 a is connected to a hot water supply connection port by a hot water outlet pipe 75. Further, a bath return pipe 76 leading to the bath (tub) 2 is provided on the entry side of the second heat exchange water pipe 72b, and a bath return pipe 77 similarly leading to the bath (tub) 2 is provided on the exit side of the second heat exchange water pipe 72b. Each is connected.

  The hot water outlet pipe 75 and the bath return pipe 76 are connected by a connecting pipe 78, and a hot water electromagnetic valve 79 for switching between closing and opening of the connecting pipe 78 is provided in the middle of the connecting pipe 78. In addition, a water amount servo 81 capable of adjusting the opening degree from a substantially closed state to a fully open state is provided in the middle of the hot water discharge pipe 75 upstream from the connection point of the connecting pipe 78 to adjust the amount of hot water discharged. A tapping temperature sensor 82 for detecting tapping temperature is provided on the downstream side of the water amount servo 81.

  Furthermore, a bypass pipe 83 branched from the water intake pipe 74 and joined to and connected to the hot water discharge pipe 75 at a predetermined location on the first heat exchange water pipe 72a side from the water quantity servo 81 is provided. A bypass adjustment valve 84 whose opening degree can be adjusted until it is fully opened is provided. The bypass adjustment valve 84 is adjusted so that hot water from the first heat exchange water pipe 72a and water via the bypass pipe 83 are mixed to become hot water at a set temperature. The inlet pipe 74 upstream of the branching point of the bypass pipe 83 is provided with a flow rate sensor 85 that detects the flow rate in the inlet pipe 74 and an incoming water temperature sensor 86 that detects the incoming water temperature.

  In the middle of the bath return pipe 76, a bath circulation pump 87 for circulating the water in the bath (tub) 2 through the recirculation circulation path (bath return pipe 76, second heat exchange water pipe 72 b, bath going-out pipe 77). Is provided. A flowing water switch 88 provided in the bath return pipe 76 detects whether water is actually circulating in the recirculation circulation path when the bath circulation pump 87 is operated.

  In addition, the bath return pipe 76 and the bath return pipe 77 are provided with a bath return temperature sensor 89a and a bath return temperature sensor 89b, respectively, for detecting the temperature in the pipe.

  The control unit 91 includes a CPU, a flash ROM that stores a program executed by the CPU, fixed data, and the like, and a RAM that temporarily stores various types of information when the CPU executes the program. Has been. Various sensors, valves, a bath circulation pump 87, and the like that the bath water heater 70 has are connected to the control unit 91.

  Furthermore, normally, a remote controller 92 is directly connected to the control unit 91 via wiring. Here, in order to operate the bath water heater 70 under the control of the control unit 20 on the hot water storage tank unit 11 side, The control unit 91 is connected to the control unit 20 via wiring, and a remote control (a common remote control for the hot water storage tank unit 11 side and the bath water heater 70) 92 is connected to the control unit 20 via wiring. The common remote control 92 includes switches for receiving various operations from the user such as designation of hot water supply set temperature and bath set temperature, start / end instructions for hot water filling and reheating, and power on / off, as well as operation state and set temperature. It is comprised with the display part etc. which display etc.

  In the hot water supply operation for supplying hot water to the hot water supply pipe 62, the controller 91 of the bath water heater 70 turns on the burner 73 so that hot water at the hot water supply set temperature set by the common remote controller 92 connected to the hot water storage tank unit 11 is discharged. / OFF, the combustion amount thereof, the opening degree of the bypass adjustment valve 84, and the like are controlled. Specifically, if the temperature of the hot water supplied from the hot water storage tank unit 11 through the connection pipe 61 is equal to or higher than the hot water supply set temperature, the hot water is supplied to the hot water supply pipe 62 without burning the burner 73 of the apparatus itself. If the temperature of the hot water supplied from the hot water storage tank unit 11 side is lower than the hot water supply set temperature, a combustion air blowing fan (not shown) in the apparatus is driven and the burner 73 is burned so as to reach the hot water set temperature. The amount of combustion and the opening degree of the bypass adjustment valve 84 are controlled.

  In the operation of pouring (hot water) into the bath (tub) 2, the opening of the water quantity servo 81 is adjusted while the burner 73 is burned by opening the pouring solenoid valve 79, thereby flowing from the water supply connection port. The hot water is heated through the first heat exchange water pipe 72a of the heat exchanger 72, and further from the hot water pipe 75 to the bath (tub) 2 through both (or one) of the connecting pipe 78, the bath return pipe 76 and the bath outlet pipe 77. Flow in (this path is a pouring circuit). At this time, the combustion amount of the burner 73, the opening degree of the bypass adjustment valve 84, and the like are controlled so that hot water having a bath setting temperature set by the user is poured by the common remote controller 92. If the hot water supplied from the hot water storage tank unit 11 through the connection pipe 61 has already reached the bath set temperature and no additional heating is required in the bath water heater 70, the hot water pouring operation is performed without burning the burner 73. Do. The bath water heater 70 checks the water level in the bath (tub) 2, and the hot water pouring operation ends when the set water level is reached.

  In the reheating operation, the hot water solenoid valve 79 is closed, and the burner 73 is burned with the bath circulation pump 87 activated. As a result, hot water in the bath (tub) 2 is taken into the bath water heater 70 through the bath return pipe 76 and heated while passing through the second heat exchange water pipe 72 b of the heat exchanger 72, and the heated hot water is heated to the bath outlet pipe 77. It is returned to the bath (tub) 2 through.

  Next, various operations of the bath hot water supply system 10 will be described.

<Exhaust heat recovery operation>
FIG. 3 shows the flow of hot water in the exhaust heat recovery operation. The path through which hot water flows in the exhaust heat recovery operation is indicated by a bold line. In the exhaust heat recovery operation for recovering the exhaust heat of the heat source unit 4 and heating the hot water in the hot water storage tank 13, the control unit 20 instructs the heat source unit 4 to operate the exhaust heat recovery pump 52. As a result, the hot water in the hot water storage tank 13 exits from the water intake 16 and is connected to the heat recovery pipe (low temperature) 53a, the exhaust heat recovery heat exchanger 51, the heat recovery pipe (high temperature) 53b, and the first three-way valve 21 in the A direction. Is circulated through the heat recovery circulation path from the return port 17 to the upper part of the hot water storage tank 13 via In the exhaust heat recovery operation, when the return temperature from the exhaust heat recovery device 50 is low, the first three-way valve 21 is moved in the B direction by the control unit 20, and when the return temperature exceeds a certain level, the first three-way valve 21 is controlled. The unit 20 switches to the A direction. Thereby, low temperature water is prevented from returning to the upper part of the hot water storage tank 13.

  The hot water is supplied from the water supply port 14 at the lower part of the hot water storage tank 13 and the hot water heated by the exhaust heat recovery operation is returned to the upper part of the hot water storage tank 13, so that the lower part of the hot water storage tank 13 has a low temperature and the upper part has a high temperature. Such a temperature gradient is formed. By continuing the exhaust heat recovery operation, the amount of hot water that accumulates in the upper portion gradually increases.

<Hot-water supply operation>
Hot water is supplied in the following control mode (1) or (2).

(1) Combustion off mode The combustion off mode is a hot water supply operation in the case where the hot water storage tank 13 has sufficiently stored heat. FIG. 4 shows the flow of hot water in the hot water supply operation. In the figure, the path through which hot water flows is indicated by a bold line. In the combustion off mode, the hot water and hot water from the hot water storage tank 13 are mixed in the mixer 23 to set the hot water supply temperature + α ° C. (α ° C. is a temperature taking into account the temperature drop in the connecting pipe 61, for example, 2 ° C.). The hot water is made and supplied to the bath water heater 70 through the connecting pipe 61. The bath water heater 70 is supplied with hot water at the set temperature of the hot water supply, and does not perform additional heating by itself, turns off the burner 73 and supplies the hot water supplied from the hot water storage tank unit 11 side to the hot water supply pipe 62 as it is. To do.

(2) Additional heating mode This is a hot water supply operation in the case where the amount of heat stored in the hot water storage tank 13 is insufficient and hot water having a hot water supply set temperature cannot be supplied in the combustion off mode, and additional heating is performed by the bath water heater 70. The flow of hot water in the hot water supply operation in the follow-up heating mode is the same as that in FIG. However, the bath water heater 70 is turned on.

  More specifically, when the hot water in the hot water storage tank 13 is slightly lower than the hot water supply set temperature and is sent to the bath water heater 70 as it is, the hot water temperature exceeds the hot water set temperature even if the bath water heater 70 is operated with the minimum capacity. The hot water from the hot water tank 13 mixed with hot water from the hot water storage tank 13 by the mixer 23 is sent to the bath water heater 70, and the hot water hot water is heated to the set hot water temperature by the bath water heater 70. When the temperature of the hot water in the hot water storage tank 13 is sufficiently lower than the hot water supply set temperature and the above-described intentional temperature reduction is not necessary, hot water (or water) having a temperature lower than the hot water supply set temperature in the hot water storage tank 13 is used as the bath hot water. The hot water is supplied to the water heater 70 and heated to the set hot water temperature by the bath water heater 70.

<Operation to prevent freezing of heat recovery piping>
When the control unit 20 detects a temperature at which the ambient temperature sensor 49 of the hot water storage tank unit 11 may be frozen, or when it is determined that the heat recovery pipe 53 may be frozen based on the temperature detected by the ambient temperature sensor 49. In addition, the freeze recovery operation of the heat recovery pipe 53 is performed. When performing the freeze prevention operation, the control unit 20 of the hot water storage tank unit 11 sets the first three-way valve 21 in the B direction, opens the pump electromagnetic valve 47, and turns on the circulation heat pump 46 and the exhaust heat recovery pump 52 of the exhaust heat recovery device 50. drive.

  FIG. 5 shows the flow of water in the freeze prevention operation of the heat recovery pipe 53 with a bold line and a thick broken line. By setting the first three-way valve 21 in the B direction, the heat recovery circulation path is switched to a bypass circulation path (path indicated by a thick solid line in FIG. 5) that bypasses the hot water storage tank 13 and passes through the bypass pipe 54. The bypass circulation path passes through the heat recovery pipe (high temperature) 53b from the exhaust heat recovery heat exchanger 51, the first three-way valve 21 in the B direction, the bypass pipe 54, and the heat recovery pipe (low temperature) 53a to recover the heat recovery heat. This is a circulation path returning to the vessel 51. By operating the exhaust heat recovery pump 52, water circulates in the detour circulation path.

  Further, by opening the pump solenoid valve 47 and operating the circulation pump 46, a part of the water in the detour circulation path circulates through the branch path (path indicated by a thick broken line in FIG. 5). That is, a part of the water flowing through the heat recovery pipe (low temperature) 53a is drawn to the merging pipe 45 side by the action of the circulation pump 46, and from the merging pipe 45, the connection pipe 61, the bath water heater 70, the hot water pipe 62, and the branch. It flows back to the heat recovery pipe (high temperature) 53b via the pipe 43, and is heated when passing through the bath water heater 70. By controlling the combustion ON / OFF of the bath water heater 70 based on the temperature detected by the return pipe temperature sensor 28, the water in the heat recovery pipe 53 is heated to a certain temperature or more, and the heat recovery pipe 53 is frozen. To prevent. The first three-way valve 21 maintains the B direction, not the A direction, at a temperature heated by the bath water heater 70 to such an extent that the heat recovery pipe 53 can be prevented from freezing.

  In the anti-freezing operation, the heat recovery circulation path is set as a bypass circulation path and the hot water storage tank 13 is bypassed. Therefore, cold water does not flow into the upper part of the hot water storage tank 13 by the anti-freezing operation. Further, when the hot water storage tank 13 is bypassed, the total amount of water circulated is smaller than when passing through the hot water storage tank 13, so that the temperature of the entire heat recovery pipe 53 can be raised in a short time by heating in the bath water heater 70. The amount of heating for preventing freezing can be reduced.

  In the case where the heat source device 4 has a temperature sensor that detects the ambient temperature (outside temperature), the temperature sensor may be used for the start control of the freeze prevention operation instead of the ambient temperature sensor 49.

  Such freezing prevention operation can prevent the heat recovery pipe 53 from freezing, so that it is not necessary to take measures such as winding a heater around the heat recovery pipe 53 at the time of construction even in an outdoor pipe in a cold region. Further, it is not necessary to provide a heating device such as an electric heater on the heat source unit 4 side in order to circulate and heat the water in the heat recovery pipe 53.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 shows a configuration of a bath hot water supply system 10B according to a second embodiment to which the hot water storage system of the present invention is applied. The hot-water supply system 10B according to the second embodiment is configured to mix hot water obtained by heating the hot-water supply with the hot-water heater 70, hot water from the hot water storage tank 13 and the hot water with the mixer 23, and hot water having a hot-water supply set temperature. The method of making hot water and making hot water (after mixing method) is adopted.

  In a bath hot water system that uses a hot water storage tank, pressure loss in the hot water storage tank and pressure loss in the connecting piping are added, compared to when hot water is supplied directly from a gas water heater or the like. Further, depending on the construction conditions, it is necessary to install the hot water storage tank unit and the gas water heater as a backup heat source machine apart from each other, and the pressure loss further increases when the connecting pipe from the hot water storage tank unit to the gas hot water heater becomes longer.

  In the case of the hot water supply hot water bath system 10 shown in the first embodiment, since the entire amount of hot water to be supplied always passes through the connection pipe 61 and the bath water heater 70, it is easily affected by pressure loss. In the post-mixing method shown in the second embodiment, the pressure loss is reduced. Thereby, the fall of the amount of hot water supply in a low water pressure area is prevented.

  As shown in FIG. 6, a bath water heater system 10B according to the second embodiment includes a hot water storage tank unit 11B, a heat source unit 4, an exhaust heat recovery device 50, and a bath water heater 70 as a backup heat source unit. It is prepared for. In this example, the heat source unit 4 is a fuel cell. In addition, the same code | symbol is attached | subjected to the same location as 1st Embodiment. In the figure, piping between apparatuses and external piping are indicated by double arrows.

  The hot water storage tank unit 11 </ b> B includes a hot water storage tank 13 that stores water supplied from the water supply pipe 12. The structure of the hot water storage tank 13 and the internal temperature sensors 18a to 18e are the same as those in the first embodiment, and a description thereof will be omitted. Further, the exhaust heat recovery device 50, the heat recovery pipe 53 that connects the exhaust heat recovery device 50 and the hot water storage tank 13, and the like are the same as those in the first embodiment, and the description thereof is also omitted.

  The hot water storage tank unit 11 </ b> B includes a mixer 30 that mixes hot water from the hot water outlet 15 of the hot water storage tank 13, hot water from the bath water heater 70, and water supply. This mixer 30 is actually a first mixer 30 a that adjusts the amount of hot water supplied from the outlet 15 of the hot water storage tank 13 and a second mixer that adjusts the amount of hot water supplied from the bath water heater 70. 30 b and a third mixer 30 c that adjusts the amount of water supplied from the water supply pipe 12.

  The inlet side of the first mixer 30a is connected to a hot water outlet 15 of the hot water storage tank 13 by piping, and an overpressure relief valve 24, an intake valve 25, and a tank outlet temperature sensor 26 are provided in the middle of the piping. . The entrance side of the second mixer 30 b is connected to the hot water supply connection port of the bath water heater 70 by a connection pipe (high temperature) 65. A return pipe temperature sensor 28 for detecting the temperature of hot water in the connection pipe (high temperature) 65 is provided at a predetermined location in the hot water storage tank unit 11B in the connection pipe (high temperature) 65. The water supply pipe 12 is connected to the entrance side of the third mixer 30c.

  The outlet side of the first mixer 30a and the outlet side of the second mixer 30b join together, and after passing through the pipe provided with the hot water supply high temperature sensor 29, join the pipe from the outlet side of the third mixer 30c. It leads to the outlet of the mixer 30. A hot water supply pipe 31 is connected to the outlet of the mixer 30. A hot water supply temperature sensor 32 and a high cut temperature sensor 33 are provided in the hot water supply pipe 31 in the vicinity of the outlet side of the mixer 30.

  The water supply pipe 12 inside the hot water storage tank unit 11B is provided with a flow rate sensor 34, a water supply temperature sensor 35, and a pressure reducing valve 36. The water supply pipe 12 branches into three downstream of these, one of which is connected to the inlet side of the third mixer 30c via a check valve 37a, and the other one via the check valve 37b. The other one is connected to the second connection port 38b of the second three-way valve 38 through the pipe 12b via the check valve 37c.

  The second three-way valve 38 includes a first connection port 38a, a second connection port 38b, and a third connection port 38c, connects the first connection port 38a and the second connection port 38b, and closes the third connection port 38c. The connection state can be switched between the C direction and the D direction in which the first connection port 38a and the third connection port 38c are connected and the second connection port 38b is closed. A pipe 31b branched from the hot water supply pipe 31 on the downstream side of the high cut temperature sensor 33 is connected to the third connection port 38c. A check valve 39 is provided in the middle of the pipe 31b. The first connection port 38 a of the second three-way valve 38 is connected to the water supply connection port of the bath water heater 70 through a connection pipe (low temperature) 66.

  Further, a drain pipe 41 leading to a predetermined drainage point is connected to the water intake 16 of the hot water storage tank 13, and a drain plug 42 for opening and closing the pipe line is provided in the middle of the drain pipe 41.

  Further, in the hot water storage tank unit 11B, the branch pipe 43 branched from the portion closer to the mixer 30 than the return pipe temperature sensor 28 of the connection pipe (high temperature) 65 joins the heat recovery pipe (high temperature) 53b. The branch pipe 43 in the hot water storage tank unit 11B is provided with a check valve 44 for preventing a back flow from the heat recovery pipe (high temperature) 53b side.

  Further, a junction pipe 45 that branches from the heat recovery pipe (low temperature) 53a inside the hot water storage tank unit 11B and joins the pipe 12b in the vicinity of the second connection port 38b of the second three-way valve 38 is provided. In the middle of the junction pipe 45, a circulation pump 46 and a pump solenoid valve 47 for supplying water from the heat recovery pipe (low temperature) 53a to the pipe 12b side are provided. The pump solenoid valve 47 opens and closes the merge pipe 45. The pump solenoid valve 47 prevents water supply from the pipe 12 b from flowing back through the circulation pump 46 and flowing into the lower part of the hot water storage tank 13 from the water intake 16. In addition, the pump solenoid valve 47 has a bath water heater 70 via the second three-way valve 38 and the connecting pipe (low temperature) 66 in the C direction when the water in the lower part of the hot water storage tank 13 comes out from the intake port 16 during a hot water supply operation described later. Prevents water from flowing in the direction of the water supply connection port.

  The configuration of the control unit 20 and the transmission / reception of signals are the same as those in the first embodiment, and a description thereof will be omitted.

  The bath water heater 70 as a backup heat source machine has the same configuration as that of the first embodiment. However, the controller 91 of the bath water heater 70 according to the second embodiment has a temperature instructed by the controller 20 on the hot water storage tank unit 11B side in the operation of discharging hot water from the hot water supply connection port to the connection pipe (high temperature) 65. The combustion amount of the burner 73 and the opening degree of the bypass adjustment valve 84 are controlled so that the hot water is discharged to the connection pipe (high temperature) 65.

  In the operation of pouring (filling) the bath (tub) 2, the combustion amount of the burner 73, the opening of the bypass adjustment valve 84, etc. so that the bath set temperature set by the user with the common remote controller 92 is poured. To control. If the hot water supplied from the hot water storage tank unit 11B side through the connection pipe (low temperature) 66 has already reached the bath set temperature and no additional heating is required in the bath water heater 70, the burner 73 is not burned. Perform hot water operation. The bath water heater 70 checks the water level in the bath (tub) 2, and the hot water pouring operation ends when the set water level is reached. The chasing operation is the same as that in the first embodiment.

  Next, various operations of the bath hot water supply system 10B will be described.

<Exhaust heat recovery operation>
FIG. 7 shows the flow of hot water in the exhaust heat recovery operation. The path through which hot water flows in the exhaust heat recovery operation is indicated by a bold line. The control and operation of the exhaust heat recovery operation are the same as in the first embodiment, and a description thereof is omitted.

<Hot-water supply operation>
The hot water storage tank unit 11B may be installed near the bath water heater 70 or may be installed far away. For example, in a house with a bath on the second floor, there is a case where the bath water heater 70 is installed on the outer wall of the second floor, and the hot water storage tank unit 11B and the heat source unit 4 are installed on the first floor. The connection pipe (high temperature) 65 and the connection pipe (low temperature) 66 connecting the apparatuses become long, resulting in an installation situation where the pressure loss is large. In the hot water supply system 10B according to the second embodiment of the present invention, an increase in pressure loss is suppressed so that a sufficient amount of hot water can be secured even in an installation situation where the piping is long and the pressure loss is large in a low water pressure region. It is supposed to do hot water supply.

  Hot water is supplied in one of the following three control modes.

(1) First mode (tank hot water mode)
The first mode is a hot water supply operation in the case where the hot water storage tank 13 has sufficiently stored heat. FIG. 8 shows the flow of hot water in the hot water supply operation in the first mode. In the figure, the path through which hot water flows is indicated by a bold line. In the first mode, hot water and hot water from the hot water storage tank 13 are mixed by the mixer 30 to make hot water at a hot water supply set temperature, and hot water is supplied. No water is sent to the bath water heater 70, no heating is performed in the bath water heater 70, and no combustion operation is performed.

  Specifically, the second mixer 30b of the mixer 30 is closed, the opening degree of the first mixer 30a and the third mixer 30c is adjusted, and the outlet side of the mixer 30 detected by the tapping temperature sensor 32 is adjusted. The hot water temperature is controlled so as to become the hot water supply set temperature. Here, for example, the detection temperature of the hot water temperature sensor 18d provided in the hot water storage tank 13 is equal to or higher than the hot water supply set temperature (actually, for example, the hot water supply set temperature + 1 ° C. in consideration of a temperature drop in the hot water supply pipe) In this case, hot water is supplied in the first mode.

(2) Second mode (hot water supply hot water mode)
The second mode is a hot water supply operation when there is no hot water available in the hot water storage tank 13. FIG. 9 shows the flow of hot water in the hot water supply operation in the second mode. In the figure, the path through which hot water flows is indicated by a bold line. In the second mode, hot water heated to a temperature higher than the hot water supply set temperature by the bath water heater 70 and hot water are mixed by the mixer 30 to supply hot water at the hot water set temperature.

  Specifically, the second three-way valve 38 is set in the C direction, and water is supplied to the bath water heater 70. Also, the first mixer 30a of the mixer 30 is closed, the opening degree of the second mixer 30b and the third mixer 30c is adjusted, and the hot water on the outlet side of the mixer 30 detected by the hot water temperature sensor 32 is adjusted. The temperature is controlled so as to become the hot water supply set temperature.

  Note that the control unit 20 instructs the bath water heater 70 to provide a hot water temperature so that the hot water temperature of the bath water heater 70 is sufficiently higher than the hot water supply set temperature. Thereby, the amount of hot water from the bath water heater 70 necessary for mixing with the water supply to obtain the hot water supply set temperature is reduced, and passes through the connection pipe (low temperature) 66, the bath water heater 70, and the connection pipe (high temperature) 65. The pressure loss caused by this can be kept small. For example, if the hot water supply set temperature is 40 ° C., hot water at 55 ° C. is obtained from the bath water heater 70. If the hot water supply set temperature is 60 ° C., 75 ° C. hot water is obtained from the bath water heater 70.

[Calculation of effect]
When the hot water supply temperature is 15 ° C, the hot water supply set temperature is 40 ° C, and the hot water supply flow rate is 8L / min. ) 65 and connecting pipe (low temperature) 66 will flow hot water at 8 L / min. On the other hand, when 55 ° C. hot water is received from the bath water heater 70, the flow rate through the connecting pipe (high temperature) 65 and the connecting pipe (low temperature) 66 may be 5 L / min, and the water supply is 3 L / min in the hot water storage tank unit 11B. To make 8L / min of 40 ° C hot water. Since the pressure loss increases as the flow velocity (proportional to the flow rate when the pipe diameter is the same) is increased, reducing the flow rate greatly contributes to pressure loss reduction.

  In the case of the hot water preheating method, even if there is heat storage in the hot water storage tank, hot water of 40 ° C and 8L / min is made with the hot water tank unit, and the entire amount is connected to the water supply connection port of the hot water heater as a backup heat source and hot water supply Will flow into the vessel. Even when there is no heat storage in the hot water storage tank, 8 L / min of water is sent from the hot water storage unit to the water heater and heated to 40 ° C. In any case, it is necessary to flow 8 L / min through the pipe to the water heater and the water heater.

  According to the experimental results using a cross-linked polyethylene pipe having an inner diameter of 16 mm, when the pipe length is 25 m (when the pipe is reciprocated to 25 m, it corresponds to a case where the bath water heater 70 and the hot water storage tank unit 11B are installed 12.5 m apart). As a result, the pressure loss of the pipe connected to the bath water heater 70 is 8 L / min and the pipe pressure loss is 11 kPa, and 5 L / min is 5 kPa. The pressure loss is reduced by 55%.

(3) Third mode (post-mixing hot water mode)
The third mode is a hot water supply operation in the case where heat is stored in the hot water storage tank 13 but the temperature is low and the hot water in the hot water storage tank 13 is not sufficient. FIG. 10 shows the flow of hot water in the hot water supply operation in the third mode. In the figure, the path through which hot water flows is indicated by a bold line. The third mode is selected, for example, when the temperature detected by the hot water temperature sensor 18d of the hot water storage tank 13 is lower than the hot water supply set temperature but not lower than a predetermined temperature (for example, 10 ° C.) above the hot water supply set temperature.

  In the third mode, the hot water heated by the bath water heater 70, the hot water from the hot water storage tank 13 and the hot water are mixed to make hot water having a hot water supply set temperature. Specifically, the hot water produced by heating the water supply with the bath water heater 70 with the second three-way valve 38 in the C direction, the water supply, and the hot water from the hot water storage tank 13 are mixed with the mixer 30 to set the hot water supply set temperature. Make hot water and supply hot water. Even if the temperature of the hot water in the hot water storage tank 13 is low, the heat stored in the hot water storage tank 13 can be used up more by mixing with the hot water received from the bath water heater 70, so the first and second Energy savings are higher than when controlling only in the mode.

  The controller 20 preferentially selects the first mode, and hot water that is not lower than the hot water set temperature by a predetermined temperature (for example, 10 ° C.) from the hot water storage tank 13 when hot water at the set temperature cannot be supplied in the first mode. When the supply is possible, the third mode is selected, and when the third mode cannot be selected, the second mode is selected.

<Operation to prevent freezing of heat recovery piping>
When the control unit 20 detects a temperature at which the ambient temperature sensor 49 of the hot water storage tank unit 11B may be frozen, or determines that the heat recovery pipe 53 may be frozen from the temperature detected by the ambient temperature sensor 49. In addition, the freeze recovery operation of the heat recovery pipe 53 is performed. When performing the freeze prevention operation, the control unit 20 of the hot water storage tank unit 11B sets the first three-way valve 21 in the B direction, the second three-way valve 38 in the C direction, opens the pump solenoid valve 47, opens the circulation pump 46 and the exhaust heat. The exhaust heat recovery pump 52 of the recovery device 50 is operated.

  FIG. 11 shows the flow of water in the freeze prevention operation of the heat recovery pipe 53 with a bold line and a thick broken line. By setting the first three-way valve 21 in the B direction, the heat recovery circulation path is switched to a bypass circulation path (path indicated by a thick solid line in the figure) that bypasses the hot water storage tank 13 and passes through the bypass pipe 54. The bypass circulation path passes through the heat recovery pipe (high temperature) 53b from the exhaust heat recovery heat exchanger 51, the first three-way valve 21 in the B direction, the bypass pipe 54, and the heat recovery pipe (low temperature) 53a to recover the heat recovery heat. This is a circulation path returning to the vessel 51. By operating the exhaust heat recovery pump 52, water circulates in the detour circulation path.

  Further, the second three-way valve 38 is set in the C direction, the pump electromagnetic valve 47 is opened, and the circulation pump 46 is operated, so that a part of the water in the detour circulation path is branched (shown by a thick broken line in FIG. 5). Cycle). That is, a part of the water flowing through the heat recovery pipe (low temperature) 53a is drawn to the merging pipe 45 side by the action of the circulation pump 46, and from the merging pipe 45, a part of the pipe 12b, the second three-way valve in the C direction. 38, when passing through the bath water heater 70 through the connection pipe (low temperature) 66, the bath water heater 70, the connection pipe (high temperature) 65, the branch pipe 43 and the heat recovery pipe (high temperature) 53b. To be heated. By controlling the combustion ON / OFF of the bath water heater 70 based on the temperature detected by the return pipe temperature sensor 28, the water in the heat recovery pipe 53 is heated to a certain temperature or more, and the heat recovery pipe 53 is frozen. To prevent. The first three-way valve 21 maintains the B direction, not the A direction, at a temperature heated by the bath water heater 70 to such an extent that the heat recovery pipe 53 can be prevented from freezing.

  In the anti-freezing operation, the heat recovery circulation path is set as a bypass circulation path and the hot water storage tank 13 is bypassed. Therefore, cold water does not flow into the upper part of the hot water storage tank 13 by the anti-freezing operation. Further, when the hot water storage tank 13 is bypassed, the total amount of water circulated is smaller than when passing through the hot water storage tank 13, so that the temperature of the entire heat recovery pipe 53 can be raised in a short time by heating in the bath water heater 70. The amount of heating for preventing freezing can be reduced.

  In the case where the heat source device 4 has a temperature sensor that detects the ambient temperature (outside temperature), the temperature sensor may be used for the start control of the freeze prevention operation instead of the ambient temperature sensor 49.

  Such freezing prevention operation can prevent the heat recovery pipe 53 from freezing, so that it is not necessary to take measures such as winding a heater around the heat recovery pipe 53 at the time of construction even in an outdoor pipe in a cold region. Further, it is not necessary to provide a heating device such as an electric heater on the heat source unit 4 side in order to circulate and heat the water in the heat recovery pipe 53.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration is not limited to that shown in the embodiment, and there are changes and additions within the scope of the present invention. Are also included in the present invention.

  If the hot water storage system of the present invention includes the hot water storage tank unit 11 (or 11B) of the bath hot water system 10 (10B), the exhaust heat recovery device 50, the bath water heater 70, and the heat source device 4 are included. For example, the exhaust heat recovery device 50 may be included in the heat source unit 4, or the bath water heater 70 may be an existing one.

  In 2nd Embodiment, although the suitable example which has 1st mode, 2nd mode, and 3rd mode as a hot water supply control mode was shown, if there exists at least 1st and 2nd mode, the structure without 3rd mode But it doesn't matter.

  In the second mode, how much hot water is made by the bath water heater 70 from the hot water set temperature may be determined as appropriate. In order to reduce the pressure loss by reducing the amount of water flowing through the water, it is desirable that the temperature be sufficiently high as long as it is mixed with the feed water to obtain hot water at the hot water set temperature. In addition, in the bath water heater 70 of the embodiment, the configuration including the incoming water temperature sensor 86 that detects the incoming water temperature is shown, but the incoming water temperature may be estimated by calculation without providing the incoming water temperature sensor 86. That is, an estimated value of the incoming water temperature Ti is calculated from Ti = To− (ηQ / W) from the hot water temperature To, the flow rate W, the gas amount (heating amount) Q measured at the last time when the hot water temperature was stabilized, and the efficiency η at this time. ), Etc. may be obtained by back calculation. In addition, efficiency (eta) measures and memorize | stores beforehand the value (efficiency (eta)) in each condition by changing tapping temperature and flow volume variously. Then, at the time of calculation, it is only necessary to obtain and use the efficiency η corresponding to the hot water temperature and the flow rate to be substituted for the calculation with reference to this memory.

  In the embodiment, the exhaust heat of the fuel cell is recovered and the water in the hot water storage tank 13 is heated. However, the heat source is not limited to the fuel cell. For example, a gas engine generator, a fuel processing device (reformer), etc. But you can.

  In the embodiment, the bath water heater 70 is a single-can two-water channel type, but it may be a water heater of a type in which the reheating of the bath and the hot water supply are performed by separate heat exchangers.

  Next, a modification of the first embodiment of the present invention will be described.

  In FIG. 5, the case where the heat source unit 4 does not operate normally in a low temperature state can be considered. In the case where there is a circumstance and timing at which heat must be applied above the temperature at which freezing is prevented, the following is performed.

  That is, the exhaust heat recovery pump 52 is operated by setting the first three-way valve 21 in the B direction while opening the pump electromagnetic valve 47 and operating the circulation pump 46 as in the first embodiment. The difference from the first embodiment is that the value of the constant temperature when the water in the heat recovery pipe 53 is heated to a constant temperature by the combustion ON / OFF control of the bath water heater 70 is, for example, freezing prevention. Although it was 2-7 degreeC, it is only a point which makes the value of this fixed temperature the heat source machine 4 side circumstance temperature (for example, 30-40 degreeC) (the modification A of 1st Embodiment below). By controlling the combustion ON / OFF of the bath water heater 70 based on the set temperature optimum for the situation of the heat source machine 4 and the temperature detected by the return pipe temperature sensor 28, the requirements of the situation of the heat source machine 4 are satisfied. May be.

  However, in the modification A of the first embodiment of the present invention, the following problems newly occur. That is, if the requirement of the temperature of the heat source device 4 side is satisfied while preventing freezing, the branch pipe 43 and the connection pipe 61 that are not originally related to the requirement of the heat source device 4 side are connected (for example, in FIGS. 6 to 11). The connection pipe (high temperature) 65 and the connection pipe (low temperature) 66 are temperatures that are unnecessary to prevent freezing.

  Therefore, the exhaust solenoid valve 47 may not be opened, the operation of the circulation pump 46 may be turned off, the first three-way valve 21 may be set in the A direction, and the exhaust heat recovery pump 52 may be operated in reverse (hereinafter, control example B). In this case, the back flow rate of the exhaust heat recovery pump 52 may be controlled according to the temperature detected by the heat recovery pipe high temperature side temperature sensor 22a, or the temperature detected by the heat recovery pipe low temperature side temperature sensor 22b is a constant temperature. By controlling the reverse rotation speed of the exhaust heat recovery pump 52 to be (for example, 20 to 30 ° C.), the hot water is not circulated through the branch pipe 43 or the connection pipe 61, so as to satisfy the requirements of the heat source unit 4 side circumstances. Anyway.

  And, when it is necessary to satisfy the temperature requirement on the heat source unit 4 side while preventing freezing, for example, the first three-way valve 21 is set in the B direction and hot water is circulated through the branch pipe 43 and the connection pipe 61. Preventing freezing (using the combustion heat of the bath water heater 70) (first embodiment or modification A of the first embodiment) and setting the first three-way valve 21 in the A direction Thus, the branch pipe 43 and the connection pipe are appropriately replaced with the heat transfer operation (control example B, the heat storage and heat transfer operation in the hot water storage tank 13) according to the circumstances of the heat source unit 4 with the control that does not circulate the hot water through the branch pipe 43 and the connection pipe 61. It is also possible to prevent a heat dissipation loss by preventing a problem that 61 becomes unnecessarily high to prevent freezing.

  In particular, the alternate operation of the modified example A and the control example B of the first embodiment (for example, during the operation of the control example B, the pump solenoid valve 47 is occasionally opened for a short time to operate the circulation pump 46 to control the temperature in the branch pipe 43. Monitored by the return pipe temperature sensor 28, when the temperature becomes close to 2 ° C. (below 7 ° C.), the operation of the exhaust heat recovery pump 52 that has been reversed is stopped and switched to the modified example A (modified example A operation) At the start, for example, the start of the exhaust heat recovery pump 52 is delayed and switched), and the fact that the branch pipe 43 and the connecting pipe 61 have risen to, for example, 30 to 40 ° C. and stabilized by the operation of the modified example A, for example, If the sensor 28, the heat recovery pipe high temperature side temperature sensor 22a, etc. are used, the heat is dissipated in the branch pipe 43 and the connection pipe 61, but the heat source 4 side is increased. Continuously meet the temperature requirements Can. During the alternate operation of the modified example A and the control example B of the first embodiment, when the operation of the modified example A of the first embodiment is resumed, the branch pipe 43 cooled as a result of performing the control example B. Since the water (for example, 2 to 7 ° C.) is mixed with the hot water (for example, 30 to 40 ° C.) in the heat recovery pipe 53 and sent to the heat source unit 4 side, the temperature of the heat source unit 4 side is temporarily not satisfied. There is. In such a case, until the hot water produced by the bath water heater 70 reaches the merging pipe 45 (for example, after confirming that the hot water has been received by the heat recovery pipe high temperature side temperature sensor 22a, the exhaust heat is exhausted). If the start-up of the recovery pump 52 is delayed, the freezing can be prevented while further reliably satisfying the temperature requirement on the heat source device 4 side (continuously heating the heat source device 4 to, for example, 30 to 40 ° C.) ( The branch pipe 43 and the connection pipe 61 can always be kept warm, for example, at 2 to 40 ° C.

2 ... Bath (tub)
4 ... Heat source machine (fuel cell)
DESCRIPTION OF SYMBOLS 10, 10B ... Bath hot water supply system 11, 11B ... Hot water storage tank unit 12 ... Water supply pipe 12b ... Pipe branched from the water supply pipe 13 ... Hot water storage tank 14 ... Water supply port 15 ... Hot water outlet 16 ... Water intake 17 ... Return port 18a ... 1st Temperature sensor 18b ... 2nd temperature sensor 18c ... 3rd temperature sensor 18d ... Hot water temperature sensor 18e ... Tank upper temperature sensor 20 ... Control part 21 ... 1st three-way valve 21a ... 1st connection port 21b ... 2nd connection port 21c ... 3rd connection port 22a ... Heat recovery pipe high temperature side temperature sensor 22b ... Heat recovery pipe low temperature side temperature sensor 23 ... Mixer 23a ... First mixer 23b ... Second mixer 24 ... Overpressure relief valve 25 ... Intake valve 26 ... Tank outlet temperature sensor 28 ... Return pipe temperature sensor 29 ... Hot water supply high temperature sensor 30 ... Mixer 30a ... First mixer 30b ... Second mixer 30c ... 3 Mixer 31 ... Hot water supply pipe 31b ... Pipe 32 ... Hot water temperature sensor 33 ... High cut temperature sensor 34 ... Flow rate sensor 35 ... Water supply temperature sensor 36 ... Pressure reducing valve 37a ... Check valve 37b ... Check valve 37c ... Check valve 38 ... 2nd three-way valve 38a ... 1st connection port 38b ... 2nd connection port 38c ... 3rd connection port 39 ... Check valve 41 ... Drain pipe 42 ... Drain plug 43 ... Branch pipe 44 ... Check valve 45 ... Merge pipe 46 ... Circulating pump 47 ... Pump solenoid valve 49 ... Ambient temperature sensor 50 ... Exhaust heat recovery device 51 ... Exhaust heat recovery heat exchanger 52 ... Exhaust heat recovery pump 53 ... Heat recovery piping 53a ... Heat recovery piping (low temperature)
53b ... Heat recovery piping (high temperature)
54 ... Bypass pipe 61 ... Connection pipe 62 ... Hot water supply pipe 65 ... Connection pipe (high temperature)
66 ... Connection piping (low temperature)
70 ... Bath water heater 72 ... Heat exchanger 72a ... First heat exchange water pipe 72b ... Second heat exchange water pipe 73 ... Burner 73a ... Gas supply pipe 74 ... Inlet pipe 75 ... Outlet pipe 76 ... Bath return pipe 77 ... Bath return pipe 77 78 ... Connecting pipe 79 ... Pouring solenoid valve 81 ... Water volume servo 82 ... Outflow temperature sensor 83 ... Bypass pipe 84 ... Bypass adjustment valve 85 ... Flow sensor 86 ... Incoming water temperature sensor 87 ... Bath circulation pump 88 ... Flow water switch 89a ... Bath going out Temperature sensor 89b ... Bath return temperature sensor 91 ... Control unit 92 ... Common remote controller

Claims (5)

A hot water storage tank to which hot water is supplied and a heating device that recovers heat from a predetermined heat source and heats the water in the hot water storage tank, when the heat storage in the hot water storage tank is insufficient for hot water at a set temperature. A hot water storage system that uses a backup heat source machine to heat the shortage,
The heating device includes a heat exchanger for recovering heat from the heat source, a forward heat recovery pipe from the hot water storage tank to the inlet side of the heat exchanger, and an outlet side of the heat exchanger to the hot water storage tank. A return heat recovery pipe, and a heat recovery pump for circulating hot water in a heat recovery circulation path that returns from the hot water storage tank to the forward heat recovery pipe, the heat exchanger, and the return heat recovery pipe to the hot water storage tank. Configured
Furthermore, a path changing unit that switches the heat recovery circulation path to a bypass circulation path that bypasses the hot water storage tank;
A branch pipe connected to the hot water outlet of the backup heat source machine, branched from the first pipe leading to the hot water tap, and joined to the return heat recovery pipe of the portion constituting the bypass circulation path;
A merging pipe that branches from the forward heat recovery pipe of the part that forms the detour circulation path and joins to a second pipe that leads to a water supply port of the backup heat source unit;
A circulation pump that is provided in the junction pipe and feeds water toward the second pipe;
A control unit;
With
The controller is
When recovering the heat of the heat source to heat the water in the hot water storage tank, the heat recovery pump is operated to circulate the water in the hot water storage tank to the heat recovery circulation path,
When supplying heat to the heat recovery pipe, the heat recovery circulation path is switched to the bypass circulation path, the heat recovery pump and the circulation pump are operated, and further controlled to be heated by the backup heat source machine. ,
When the hot water supply port supplies heat to the heat recovery pipe, it does not switch between the state where the hot water supply port is connected to the branch pipe and the state where the hot water supply port is connected to the first pipe ahead of the branch point of the branch pipe. A hot water storage system in which a hot water supply port of a heat source device is in a state of communicating with both the branch pipe and the first pipe ahead of the branching point of the branch pipe .   The branch pipe is provided with a check valve that prevents the flow from the return heat recovery pipe side to the first pipe side.
  The hot water storage system according to claim 1. A mixer for supplying hot water by mixing hot water from the hot water supply port of the backup heat source machine flowing in through the first pipe, hot water from the hot water storage tank, and water supply at a set mixing ratio;
Water is supplied to the water supply port of the backup heat source machine through the second pipe,
The hot water storage according to claim 1 or 2 , wherein the control unit controls heating by the backup heat source unit and a mixing ratio of the mixer so that hot water having a set temperature is supplied from the mixer. system. Mixing hot water and water supply from the hot water outlet of the hot water storage tank at a set mixing ratio, and further comprising a mixer connected to the outlet side of the second pipe leading to the water supply port of the backup heat source machine,
The control unit controls the mixing ratio of the mixer so that hot water at a set temperature is supplied from the backup heat source unit without additional heating by the backup heat source unit or by adding heating by the backup heat source unit. The hot water storage system according to claim 1 or 2 , characterized in that The path changing unit, any one of claims 1 to 5 the temperature of hot water flowing from the return heat recovery pipe side if there is less than a predetermined temperature and switches the heat recovery circulating path to the bypass circulation route The hot water storage system according to item 1.

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