Energy Supply System

Abstract

To provide an energy supply system capable of properly supplying hot water of high temperature when a fuel gas is not supplied by a simple constitution effectively utilizing a constitution provided in a power generation portion and a water heater.SOLUTION: An energy supply system has: a fuel cell-type power generation portion M generating power by supply of a fuel gas; a heat exchange flow channel 20 for circulating hot water / water in a hot water storage tank 3 via a heat exchange portion 2 by a circulation pump 22; a hot water storage-side anti-freezing heater H1 provided in the heat exchange flow channel 20; and an external anti-freezing heater provided in a hot water / water flow channel inside of a water heater B. An operation control portion C executes a heater heating-type hot water supply processing for heating the hot water / water in the hot water storage tank 3 by operating the hot water storage-side anti-freezing heater H1 in a state of driving the circulation pump 22 when the fuel gas is not supplied, and heating tank-delivery hot water / water supplied from the hot water storage tank 3 by the external anti-freezing heater and supplying hot water when supply of hot water is instructed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to an energy supply system including a fuel cell power generation unit that generates power by supplying fuel gas, a hot water storage tank that stores hot water, a heat exchange flow path that circulates the hot water in the hot water storage tank through a circulation pump through a heat exchange unit to which heat generated during power generation in the power generation unit is transmitted, a water heater that heats the hot water supplied from the hot water storage tank with the combustion heat of the fuel gas to produce hot water, and an operation control unit.

Background Art

[0002] As an energy supply system, while generating power in a power generation unit with supplied fuel gas, at the same time, the waste heat generated during this power generation is recovered in a heat exchange unit to raise the temperature of the hot water in the hot water storage tank, and while using the power obtained by power generation, there is a cogeneration system that uses the high-temperature hot water stored in the hot water storage tank while heating it with a water heater (see, for example, Patent Document 1).

[0003] In the energy supply system of Patent Document 1, when fuel gas is not supplied, by operating a freeze prevention heater on the hot water storage side provided in the heat exchange flow path in a state where the circulation pump is driven, even when fuel gas is not supplied, the hot water in the hot water storage tank is heated up, and it is described that the heated hot water in the hot water storage tank is used to produce hot water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the system described in Patent Document 1, hot water can be dispensed from the heated hot water storage tank even when fuel gas is not supplied. However, since the anti-freeze heater on the hot water storage side has a small heating capacity intended to prevent freezing, it takes a considerably long time to raise the entire volume of hot water stored in the tank to a predetermined high temperature (for example, 70°C). Therefore, when dispensing hot water from the hot water storage tank, there was a risk that high-temperature hot water could not be properly dispensed due to the hot water in the storage tank not being sufficiently heated.

[0006] Incidentally, as an energy supply system, in order to prevent the hot water stored in the hot water storage tank from being dispensed at high temperature, a mixing valve is installed to mix cold water with the hot water discharged from the tank. The mixing valve is controlled so that the temperature of the hot water discharged from the tank mixed with cold water reaches the set supply temperature (for example, 35°C). If the temperature of the hot water discharged from the tank mixed with cold water is lower than the set target temperature, the hot water discharged from the tank is heated (heated up) to the set target temperature by a water heater before being dispensed. In such an energy supply system, even if the hot water in the storage tank is heated to a high temperature (for example, 70°C) by the operation of the storage tank's anti-freeze heater, cold water is mixed with the hot water discharged from the tank. As a result, the temperature of the hot water discharged from the tank, mixed with cold water, may fall below the set target temperature, potentially leading to the inconvenience of dispensing hot water that is below the set target temperature.

[0007] Furthermore, while it is sometimes possible to fill a bathtub by supplying hot water from a storage tank, the amount of hot water stored in the storage tank is generally considerably less than the amount of hot water supplied to the bathtub. Therefore, when filling a bathtub, it becomes necessary to supply cold water that has not been heated to a higher temperature to the bathtub after supplying the hot water stored in the storage tank, which could lead to the inconvenience of the bathtub water temperature being considerably lower.

[0008] The present invention has been made in view of the above circumstances, and its purpose is to provide an energy supply system that can appropriately dispense high-temperature hot water when fuel gas is not supplied, with a simple configuration that effectively utilizes the components provided in the power generation unit and the water heater. [Means for solving the problem]

[0009] The energy supply system according to the present invention comprises a fuel cell type power generation unit that generates electricity by supplying fuel gas, a hot water storage tank for storing hot water, a heat exchange flow path that circulates the hot water in the hot water storage tank through a heat exchange unit to which heat generated by the power generation unit is transferred, a water heater that heats the hot water supplied from the hot water storage tank with the combustion heat of the fuel gas and dispenses it, and an operation control unit, and its characteristic configuration is as follows: The hot water storage side freeze prevention heater is provided in the heat exchange flow path, and the hot water flow path inside the water heater is provided in an external freeze prevention heater. The operation control unit is characterized by the fact that, when the fuel gas is not supplied, it operates the storage-side anti-freeze heater while the circulation pump is running to raise the temperature of the hot water in the storage tank, and when hot water is dispensed, it performs a heater-heated hot water supply process in which it raises the temperature of the hot water discharged from the tank using the external anti-freeze heater before dispensing the hot water.

[0010] With this configuration, even if fuel gas is not supplied, if external power is available, the anti-freeze heater on the hot water storage side is activated while the circulation pump is running to raise the temperature of the hot water in the storage tank. Then, when hot water is ordered to be dispensed, the hot water supplied from the storage tank is heated by the external anti-freeze heater to dispense high-temperature hot water.

[0011] In other words, by effectively utilizing the storage-side anti-freeze heater, which will be installed in the heat exchange flow path to prevent freezing, and the external anti-freeze heater, which will be installed in the hot water flow path inside the water heater to prevent freezing, it will be possible to properly dispense high-temperature hot water when fuel gas is not supplied.

[0012] In short, the characteristic configuration of the energy supply system of the present invention allows for the proper supply of high-temperature hot water when fuel gas is not available, through a simple configuration that effectively utilizes the components provided in the power generation unit and the water heater.

[0013] Further characteristic configurations of the energy supply system of the present invention are: A mixing valve is provided to mix cold water with the hot water supplied from the tank. The operation control unit controls the mixing valve in the heater-heated hot water supply process so that the temperature of the hot water discharged from the tank, mixed with the cold water, reaches the set supply temperature, or so that the cold water is mixed with the hot water discharged from the tank at a set ratio. Furthermore, when the temperature of the hot water discharged from the tank, mixed with the cold water, is lower than the set target temperature, the unit activates the external freeze prevention heater to bring the temperature of the hot water discharged from the tank closer to the set target temperature.

[0014] This configuration prevents the high-temperature hot water stored in the storage tank from being dispensed at a high temperature by controlling the mixing valve so that the temperature of the hot water dispensed from the tank, mixed with cold water, reaches the set supply temperature, or by mixing cold water with the hot water dispensed from the tank at a set ratio. Furthermore, when the temperature of the hot water discharged from the tank, which is mixed with cold water, is lower than the set target temperature, an external anti-freeze heater is activated to raise the temperature of the hot water discharged from the tank to bring it closer to the set target temperature, thereby enabling the proper discharge of hot water at a temperature close to the set target.

[0015] In short, according to the further characteristic configuration of the energy supply system of the present invention, it is possible to appropriately dispense hot water that is close to the set target temperature while avoiding the high-temperature hot water stored in the hot water storage tank being dispensed at a high temperature.

[0016] Further characteristic configurations of the energy supply system of the present invention are: A mixing valve is provided to mix cold water with the hot water supplied from the tank. The operation control unit, in the heater-heated hot water supply process, operates the external anti-freeze heater and controls the mixing valve to adjust the temperature of the tank-discharged hot water, which is mixed with the cold water, to a temperature at which the estimated discharge temperature of the hot water dispensed from the water heater becomes the set target temperature.

[0017] With this configuration, the hot water supplied from the tank, mixed with cold water, is heated by an external anti-freeze heater before being dispensed. The mixing valve is controlled to adjust the temperature of the hot water supplied from the tank, mixed with cold water, so that the estimated dispensed temperature of the hot water supplied from the water heater, heated by the external anti-freeze heater, reaches the set target temperature. This prevents the hot water stored in the storage tank from being dispensed at its high temperature, while still ensuring that hot water at a temperature close to the set target temperature is dispensed appropriately.

[0018] In short, according to the further characteristic configuration of the energy supply system of the present invention, it is possible to appropriately dispense hot water close to the set target temperature while avoiding the high-temperature hot water stored in the hot water storage tank being dispensed at a high temperature.

[0019] Further characteristic configurations of the energy supply system of the present invention are: A mixing valve is provided to mix cold water with the hot water supplied from the tank. The operation control unit controls the mixing valve to adjust the temperature of the tank-discharged hot water, which is mixed with cold water, to a temperature such that the estimated discharge temperature of the hot water dispensed from the water heater becomes the set target temperature when the external anti-freeze heater is activated, and when the temperature of the tank-discharged hot water, which is mixed with cold water, is lower than the set target temperature, it activates the external anti-freeze heater to bring the temperature of the tank-discharged hot water closer to the set target temperature.

[0020] According to this configuration, assuming that the tank-discharged hot water mixed with cold water is heated by an external anti-freeze heater before being dispensed, the mixing valve is controlled to adjust the temperature of the tank-discharged hot water mixed with cold water so that the estimated dispensed temperature of the hot water heated by the external anti-freeze heater and dispensed from the water heater becomes the set target temperature. When the temperature of the hot water sent out from the tank, which is mixed with cold water, is lower than the set target temperature, the external anti-freezing heater is activated to bring the temperature of the hot water sent out from the tank closer to the set target temperature. Therefore, while avoiding the high-temperature hot water stored in the hot water storage tank from being discharged at a high temperature, it is possible to appropriately discharge hot water at a temperature as close as possible to the set target temperature.

[0021] In short, according to a further characteristic configuration of the energy supply system of the present invention, while avoiding the high-temperature hot water stored in the hot water storage tank from being discharged at a high temperature, it is possible to appropriately discharge hot water at a temperature as close as possible to the set target temperature.

[0022] A further characteristic configuration of the energy supply system of the present invention is a bathtub water heating heater is provided in a circulation flow path for circulating bathtub water between a bathtub to which hot water is supplied from the water heater and the water heater by a bathtub water circulation pump. When water filling is instructed, the operation control unit supplies hot water of a set water filling amount discharged by the heater heating type hot water supply process to the bathtub, and then, when the temperature of the bathtub water is lower than the set water filling temperature, the operation control unit drives the bathtub water circulation pump in a state where the bathtub water heating heater is activated to raise the temperature of the bathtub water, thereby performing a heater type water filling process.

[0023] According to this characteristic configuration, when water filling is instructed, hot water of a set water filling amount discharged by the heater heating type hot water supply process is supplied to the bathtub. In addition, when supplying hot water of the set water filling amount to the bathtub, when the high-temperature hot water stored in the hot water storage tank runs out, unheated hot water (cold water) is supplied to the bathtub.

[0024] When the temperature of the bathtub water is lower than the set water filling temperature when hot water of the set water filling amount is supplied to the bathtub, the temperature of the bathtub water is raised to the set water filling temperature by driving the bathtub water circulation pump in a state where the bathtub water heating heater is activated to raise the temperature of the bathtub water.

[0025] In short, according to a further feature configuration of the energy supply system of the present invention, when fuel gas is not supplied, it is possible to fill the bathtub with hot water at a set temperature to a set volume. [Brief explanation of the drawing]

[0026] [Figure 1] This is a diagram showing the configuration of an energy supply system. [Figure 2] This is a diagram showing the configuration of a water heater. [Figure 3] This is a flowchart for hot water management and control. [Figure 4] This is a flowchart of the control scheme for raising the temperature inside the tank. [Figure 5] This is a flowchart of the control scheme for heating water during hot water supply. [Figure 6] This is a flowchart of the control configuration for bathtub hot water supply. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the drawings. [Overall structure] As shown in Figure 1, a combined heat and power energy supply system is configured with a power generation module M (an example of a fuel cell type power generation unit) that generates electricity using fuel gas such as city gas supplied from an external source, a power conversion unit 1 that converts the electricity generated by the power generation module M into alternating current, a waste heat recovery heat exchange unit 2 (an example of a heat exchange unit) that recovers waste heat generated when the power generation module M is powered, a hot water storage tank 3 that stores hot water heated by the waste heat recovered by the waste heat recovery heat exchange unit 2, a water heater B that heats the hot water discharged from the hot water storage tank 3 with the combustion heat of the fuel gas to dispense hot water, and an operation control device C (an example of an operation control unit) that controls the entire system. In other words, the energy supply system described as an example is configured to include a power generation unit A, which is equipped with a power generation module M and a hot water storage tank 3, and a water heater B.

[0028] Incidentally, in this embodiment, we illustrate a case where the operation control device C consists of a power generation control device P provided for the power generation unit A and a hot water supply control device Q provided for the water heater B. However, the power generation control device P and the hot water supply control device Q may also be configured as a single control device. The power generation control device P and the hot water supply control device Q are configured to receive control commands from a remote controller (hereinafter referred to as "remote control") R installed inside the house, and to be able to communicate via the remote control R. The remote control R is configured to issue control commands such as an operation switching command to switch the entire energy supply system between an operating state and a stopped state, a target temperature for hot water supply, a command to fill the bathtub, a set amount of hot water to fill and a set temperature for filling the bathtub, and a heater hot water supply switching command to start or stop the heater-heated hot water supply process described later, and is also configured to issue commands for various other types of information.

[0029] The power generation unit A houses a power generation module M, a power conversion unit 1, a heat recovery heat exchange unit 2, a hot water storage tank 3, and an operation control device C in a casing, and is installed outdoors in a typical household. The power conversion unit 1 supplies the converted AC power to the distribution board 5. The distribution board 5 combines the power supplied from the commercial power source 6 and the power supplied from the power conversion unit 1 and supplies it to the electrical loads 7, such as electrical appliances, inside the house.

[0030] [Details of the power generation module] The power generation module M is configured to house a reforming section 11, which is supplied with fuel gas such as city gas via a fuel gas supply line 10, and a cell stack 12, which consists of multiple solid oxide fuel cell cells stacked on top of each other, inside a high-temperature container 13.

[0031] The reforming section 11 processes the fuel gas using steam reforming to produce a reformed gas with a high hydrogen content, and is configured to supply the generated reformed gas to the cell stack 12. Incidentally, the reforming unit 11 is supplied with steam in addition to fuel gas, but since its configuration is well known, a detailed explanation will be omitted in this embodiment.

[0032] Although not shown in the diagram, air (oxygen-containing gas) is supplied to the inside of the high-temperature container 13. The cell stack 12 is configured to generate electricity by passing reformed gas through the fuel electrode and by passing air (oxygen-containing gas) supplied to the inside of the high-temperature container 13 through the oxygen electrode.

[0033] Furthermore, the reformed gas that has passed through the fuel electrode is combusted using the air (oxygen-containing gas) that has passed through the oxygen electrode and the air (oxygen-containing gas) supplied to the inside of the high-temperature container 13, and the reforming section 11 is heated by the heat of this combustion. Furthermore, the exhaust gas passage 8, which discharges the exhaust gas obtained by burning the reformed gas from the high-temperature container 13, is provided in a manner that it passes through the aforementioned exhaust heat recovery heat exchange section 2. In other words, the exhaust heat recovery heat exchange section 2 is configured to recover the exhaust heat from the exhaust gas obtained by burning the reformed gas after it has passed through the fuel electrode.

[0034] The fuel gas supply passage 10 is equipped with a gas shut-off valve 14 that opens and closes the fuel gas supply passage 10 to intermittently supply fuel gas, and a pressure sensor 15 that detects the fuel gas supply pressure. Incidentally, when the fuel gas supply pressure detected by the pressure sensor 15 falls below the set reference pressure, the operation control device C determines that fuel gas is not being supplied to the power generation module M and the water heater B, and controls the gas shut-off valve 14 to close until the fuel gas supply pressure detected by the pressure sensor 15 becomes equal to or greater than the set reference pressure. The operation control device C is configured to execute heater-heated hot water supply when a heater-heated hot water supply switching command, which commands the start of the heater-heated hot water supply treatment described later, is issued when fuel gas is not supplied, and to stop the heater-heated hot water supply treatment when a heater-heated hot water supply switching command, which commands the stop of the heater-heated hot water supply treatment, is issued.

[0035] [Details of waste heat recovery] The hot water storage tank 3 is configured as a sealed type. A circulation path 20 (an example of a heat exchange flow path) for circulating hot and cold water is provided, connecting the bottom and top of the hot water storage tank 3 via the heat recovery heat exchange section 2. A circulation pump 22 is provided to circulate the hot and cold water through the circulation path 20, returning the hot and cold water taken from the bottom of the hot water storage tank 3 to the top of the hot water storage tank 3.

[0036] The circulation path 20 consists of a forward path 20a connecting the bottom of the hot water storage tank 3 and the heat recovery heat exchange unit 2, and a return path 20b connecting the heat recovery heat exchange unit 2 and the top of the hot water storage tank 3. Furthermore, the forward path 20a is equipped with the aforementioned circulation pump 22, a storage-side anti-freeze heater H1 that heats the hot water flowing through the circulation path 20, and a radiator 24 that cools the hot water flowing through the circulation path 20, all aligned with the direction of hot water flow. Furthermore, the radiator 24 is provided to cool the hot water circulating in the circulation path 20 when the entire inside of the hot water storage tank 3 is filled with hot water at the target temperature (for example, 70°C) (i.e., when it has boiled).

[0037] Incidentally, although not shown in the diagram, the pump drive circuit of the circulation pump 22 and the heater drive circuit of the hot water storage side freeze prevention heater H1 are configured to be supplied with commercial power from the commercial power supply 6 or power from the power conversion unit 1. In other words, the circulation pump 22 and the hot water storage side freeze prevention heater H1 are configured to be driven by the commercial power supply 6 as an external power source when the power generation unit A is stopped, and by the power from the power conversion unit 1 when the power generation unit A is generating power.

[0038] Upstream of the circulation pump 22 in the outbound path 20a, a cold water side sensor 25 is provided as a temperature sensor to detect the temperature of the hot water taken from the bottom of the hot water storage tank 3. Furthermore, the return path 20b is equipped with a hot water side sensor 26, which acts as a temperature sensor to detect the temperature of the hot water heated in the heat recovery heat exchange unit 2.

[0039] Furthermore, the bypass path 20c is provided in a manner that connects the flow path portion corresponding to the area between the chilled water side sensor 25 and the circulation pump 22 in the outbound path 20a with the return path 20b. Furthermore, a three-way switching bypass valve 21 is provided to switch between a hot water storage tank flow state, in which the hot water flowing in the return path 20b flows to the upper part of the hot water storage tank 3, and a bypass flow state, in which the hot water flowing in the return path 20b flows to the bypass path 20c. Furthermore, the system is configured to allow switching to a bypass flow state when activating the storage-side anti-freeze heater H1 to prevent freezing.

[0040] Incidentally, the water supply channel 30 is equipped with a water supply channel anti-freeze heater H2, and the hot water outlet channel 31 is equipped with a hot water outlet channel anti-freeze heater H3. Furthermore, when the power generation control device P activates the storage-side anti-freeze heater H1 to prevent freezing due to a decrease in outside air temperature, etc., it is configured to also activate the water supply channel anti-freeze heater H2 and the hot water outlet channel anti-freeze heater H3. Furthermore, the storage-side anti-freeze heater H1, the water supply channel anti-freeze heater H2, and the outlet channel anti-freeze heater H3 are collectively referred to as the power generation-side heater Ha.

[0041] Furthermore, the power generation control device P is configured to perform a waste heat recovery type hot water storage treatment in which, when the power generation module M is operating, it controls the operation of the circulation pump 22 in such a way that it adjusts the amount of hot water circulated through the circulation path 20 so that the temperature of the hot water supplied to the upper part of the hot water storage tank 3 through the circulation path 20 reaches a target temperature (for example, 70°C) in order to store hot water in the hot water storage tank 3 in a state where temperature stratification is formed. Furthermore, a temperature sensor (not shown) that detects the temperature of the hot water stored in the hot water storage tank 3 is configured to stop the circulation of the hot water through the circulation path 20 when it detects that the entire volume of hot water stored in the hot water storage tank 3 has reached a target temperature (for example, 70°C). Incidentally, the above target temperature may be automatically set to different temperatures depending on the season, such as summer, winter, or transitional season, or it may be configured so that the user can set their preferred temperature using the remote control R.

[0042] Therefore, the hot water stored in the hot water storage tank 3 is supplied to the water heater B through the hot water outlet passage 31 connected to the top of the hot water storage tank 3, and the water heater B is configured to dispense hot water to hot water consumption points such as the hot water tap 38 and the bathtub 50 (see Figure 2). Incidentally, when the hot water stored in the hot water storage tank 3 is released, it is supplied from a water source such as the public water supply through the water supply channel 30 connected to the bottom of the hot water storage tank 3.

[0043] Furthermore, when the power generation control device P (operation control device) is not supplied with fuel gas and a heater hot water supply switching command is issued to start heater-heated hot water supply processing, it is configured to activate the storage-side freeze prevention heater H1 and drive the circulation pump 22 at the set driving conditions, circulating hot water through the circulation path 20 to raise the temperature of the hot water stored in the storage tank 3. Additionally, when a temperature sensor (not shown) that detects the temperature of the hot water stored in the storage tank 3 detects that the entire amount of hot water stored in the storage tank 3 has reached the target temperature (for example, 70°C), the circulation of hot water through the circulation path 20 is stopped. The hot water supplied from the hot water storage tank 3 is heated (heated up) by an external anti-freeze heater Hb, which will be described later, and then dispensed from the water heater B.

[0044] (Details of the hot spring water supply configuration) The hot water outlet channel 31 is equipped with a mixing valve 33 that mixes the cold water supplied from the branch channel 30A, which is branched off from the water supply channel 30, with the tank-discharged hot water flowing through the hot water outlet channel 31. A water supply side temperature sensor 35 is provided in the branch channel 30A of the water supply channel 30, an upstream side temperature sensor 37 is provided upstream of the mixing valve 33 in the hot water outlet channel 31 to measure the temperature of the hot water discharged from the tank before mixing with cold water, and a downstream side temperature sensor 36 is provided downstream of the mixing valve 33 in the hot water outlet channel 31 to measure the temperature of the hot water discharged from the tank after mixing with cold water.

[0045] Furthermore, when the power generation control device P supplies tank-discharged hot water to the water heater B in response to the opening of the hot water tap 38 or the start of filling the tank, etc., when the power generation module M is operating with fuel gas supplied or when fuel gas is not supplied, the device is configured to control the mixing valve 33 so that the temperature of the tank-discharged hot water mixed with cold water reaches the set supply temperature (for example, 35°C) by feedforward control based on detection information from the water supply side temperature sensor 35 and the upstream side temperature sensor 37, and feedback control based on detection information from the downstream side temperature sensor 36. Furthermore, in cases where fuel gas is not supplied, etc., if the temperature of the hot water discharged from the tank before mixing with chilled water is below the set supply temperature (for example, 35°C), the hot water discharged from the tank will be supplied to water heater B without mixing with chilled water.

[0046] Next, as described below, when the power generation module M is in operation and supplied with fuel gas, the hot water supply control device Q is configured to heat the supplied hot water from the tank to a set target temperature (for example, 40°C) using the combustion heat of the fuel gas before dispensing it. Furthermore, when fuel gas is not being supplied, the hot water supply control device Q is configured to heat the supplied hot water from the tank using an external anti-freeze heater Hb, which is equipped on the water heater B and will be described later, to bring it closer to a set target temperature (for example, 40°C) before dispensing it as hot water.

[0047] Furthermore, a cold water channel 32 is provided to supply cold water from the branch channel 30A to the downstream side of the mixing valve 33 in the hot water outlet channel 31, and a cold water channel on / off valve 34 is provided to open and close this cold water channel 32. Furthermore, in cases where, for example, the hot water in the hot water storage tank 3 cannot be used due to sterilization measures for the hot water storage tank 3, the cold water channel 32 is opened, and cold water from the cold water channel 32 is supplied to the water heater B for heating, thereby enabling the supply of hot water at a set target temperature (for example, 40°C).

[0048] Incidentally, when fuel gas is not being supplied, instead of controlling the mixing valve 33 so that the temperature of the tank-discharged hot water mixed with chilled water reaches the set supply temperature (for example, 35°C), the system may be implemented by controlling the mixing valve 33 to mix chilled water with the tank-discharged hot water at a set ratio.

[0049] [Details of the water heater] As shown in Figure 2, the water heater B is basically configured to perform a hot water supply process that supplies hot water to the bathtub 50 and the hot water tap 38, a heat medium supply process that circulates and supplies a heat medium for heating to heat consumption terminals 51 such as floor heating panels and bathroom heating and drying machines, and a reheating process that reheats the bath water in the bathtub 50.

[0050] In other words, the hot water control device Q is configured to control the operation of the water heater B based on commands from the remote control R and the bathroom remote control R2, and to perform a hot water supply process that supplies hot water to the bathtub 50 and the hot water tap 38, a heat medium supply process that circulates and supplies to the heat consumption terminal 51, and a reheating process that reheats the bath water in the bathtub 50. Incidentally, the bathroom remote control R2 is installed on a wall adjacent to the bathtub 50 inside the bathroom Y where the bathtub 50 is installed.

[0051] The water heater B of this embodiment includes a water heater F that heats the water from the inlet channel 52 through which the hot water supplied from the outlet channel 31 of the power generation unit A flows, and supplies the heated water to the hot water tap 38 and the bathtub 50, and a heat transfer medium heating unit G that heats the heat transfer medium that is circulated and supplied to the heat consumption terminal 51.

[0052] Furthermore, a hot water supply channel 53 is provided to supply hot water heated in the hot water heating unit F to the hot water tap 38, and a hot water supply channel 89 is provided branching off from the hot water supply channel 53 to supply the hot water flowing through the hot water supply channel 53 to the bathtub 50. Furthermore, a heat medium circulation circuit J is provided for circulating the heat medium between the heat medium heating unit G and the heat consumption terminal 51, and a heat medium circulation pump Jp is provided for circulating the heat medium through the heat medium circulation circuit J.

[0053] (Configuration of the heating unit for hot water supply and the heating unit for the heat transfer medium) The hot water heating unit F is configured to heat the hot water flowing through the hot water heat exchanger 54 with the combustion gas from the hot water burner 55, with an inlet passage 52 connected to the inlet side and a hot water passage 53 connected to the outlet side, a hot water burner 55 that heats the hot water heat exchanger 54, and a hot water blower fan 56 that supplies combustion air to the hot water burner 55.

[0054] The heat transfer medium heating unit G is configured to heat the heat transfer medium flowing through the heat transfer medium heating unit G with the combustion gas from the heat transfer medium heating unit G, with the return path 57 of the heat transfer medium circulation circuit J connected to the inlet side and the outflow path 58 of the heat transfer medium circulation circuit J connected to the outlet side, a heat transfer medium heating burner 60 that heats the heat transfer medium heating unit G, and a heat transfer medium blower fan 61 that supplies combustion air to the heat transfer medium heating burner 60.

[0055] A hot water burner 55 equipped in the hot water heating unit F is connected to a hot water gas supply line 62 that supplies fuel gas for general household use, and a heat medium heating burner 60 equipped in the heat medium heating unit G is connected to a heat medium gas supply line 63 that supplies fuel gas for general household use. The hot water supply gas supply passage 62 and the heat transfer medium gas supply passage 63 are equipped with an electromagnetic gas proportional valve 64 for adjusting the amount of fuel gas supplied and an intermittent valve 65 for intermittently supplying fuel gas. Although not shown in the diagram, an igniter for ignition and a flame rod for detecting ignition will be provided near the hot water burner 55 and the heat transfer medium heating burner 60.

[0056] (Hot water supply configuration) The water inlet channel 52 is equipped with a water supply thermistor 66 for detecting the water supply temperature and a water flow sensor 67 for detecting the water supply amount. The portion of the water inlet channel 52 downstream of the water supply thermistor 66 and water flow sensor 67 is connected to the hot water supply channel 53 by a water supply bypass channel 68 that bypasses the hot water heat exchanger 54.

[0057] At the connection point between the hot water supply line 53 and the cold water supply bypass line 68, a mixing valve 69 is provided to adjust the mixing ratio of the amount of hot water from the hot water heat exchanger 54 and the amount of cold water from the cold water supply bypass line 68. Upstream of the connection point of the hot water supply line 53 to the cold water supply bypass line 68, a hot water outlet thermistor 70 is provided to detect the temperature of the hot water supplied from the hot water heat exchanger 54. Downstream of the connection point of the hot water supply line 53 to the cold water supply bypass line 68, in order from upstream, a hot water supply thermistor 71 is provided to detect the temperature of the hot water after it has been mixed by the mixing valve 69, a water proportional valve 72 is provided to adjust the amount of hot water, and an interruption detection water volume sensor 73 is provided to detect interruptions in general hot water supply.

[0058] Incidentally, the interruption detection water volume sensor 73 will detect when the hot water tap 38 is opened while the bathtub 50 is being filled with hot water, and this detection will interrupt the filling process.

[0059] (Configuration for heat medium circulation) An expansion tank 74 is interposed in the return path 57 of the heat medium circulation circuit J, and the heat medium circulation pump Jp described above is installed downstream of the expansion tank 74 in the return path 57 to draw hot water from the expansion tank 74 and send it to the heat exchanger 59 for heating the heat medium.

[0060] The supply path 58 of the heat medium circulation circuit J is provided with a heat medium thermistor 75 (an example of a heat medium temperature detection unit) for detecting the temperature of the heat medium after it has been heated in the heat exchanger 59 for heating the heat medium, and a terminal thermal valve 76 for intermittently supplying the heat medium to the heat consumption terminal 51. Furthermore, the section downstream of the heat transfer fluid thermistor 75 in the outbound path 58 and the section upstream of the expansion tank 74 in the return path 57 are connected by a circulation bypass path 77 that circulates hot water by bypassing the heat consumption terminal 51.

[0061] (Configuration for reheating) A reheating passage 78 is provided that connects the downstream side of the connection point of the circulation bypass passage 77 in the outbound path 58 of the heat medium circulation circuit J and the upstream side of the connection point of the circulation bypass passage 77 in the return path 57 of the heat medium circulation circuit J. The reheating passage 78 is equipped with a reheating heat exchanger 79 and a reheating thermal valve 80 for reheating the bath water in the bathtub 50.

[0062] A bath water circulation circuit K (an example of a circulation path) for circulating the bath water inside the bathtub 50 is provided, connected to a circulation adapter 81 mounted on the lower side of the side wall of the bathtub 50 and also connected to a reheating heat exchanger 79. In other words, the bath water return path 82 in the bath water circulation circuit K is provided in a state that connects the circulation adapter 81 and the reheating heat exchanger 79, the bath water supply path 83 in the bath water circulation circuit K is provided in a state that connects the reheating heat exchanger 79 and the circulation adapter 81, and a bath water circulation pump 84 that circulates bath water through the bath water circulation circuit K is provided in the bath water return path 82.

[0063] Incidentally, the reheating heat exchanger 79 is a liquid-to-liquid heat exchanger that exchanges heat between the bath water flowing through the bath water circulation circuit K and the heat transfer medium flowing through the heat transfer medium circulation circuit J, and also corresponds to the bath water heating section D that heats the bath water flowing through the bath water circulation circuit K.

[0064] Therefore, by operating the heat transfer fluid circulation pump Jp with the terminal thermal valve 76 closed and the reheating thermal valve 80 open, the heat transfer fluid heated in the heat transfer fluid heating heat exchanger 59 is circulated and supplied to the reheating heat exchanger 79 while bypassing the heat consumption terminal 51. In this state, the bath water circulation pump 84 is activated to circulate the bath water stored inside the bathtub 50 to the reheating heat exchanger 79 through the bath water return path 82 and the bath water supply path 83, thereby enabling the reheating of the bath water in the bathtub 50.

[0065] The bathtub water return path 82 is equipped with, in order from the upstream side, a bathtub water temperature detection sensor 85 for detecting the temperature of the bathtub water returning from the bathtub 50, a water level sensor 86 for detecting the water level inside the bathtub by detecting the pressure of the hot water inside the bathtub water return path 82, a water flow switch 87, and the aforementioned bathtub water circulation pump 84. Furthermore, the bath water supply path 83 is equipped with a bath water supply temperature detection sensor 88 that detects the temperature of the bath water heated by the reheating heat exchanger 79.

[0066] (Configuration for hot water filling) From a point between the water supply bypass path 68 and the interruption detection water volume sensor 73 in the hot water supply path 53, the aforementioned hot water filling path 89 for supplying hot water from the hot water supply path 53 to the bathtub 50 is branched off, and this hot water filling path 89 is connected to the bathtub water return path 82. This hot water supply channel 89 is equipped with, in order from the upstream side, a solenoid valve 90 for opening and closing the hot water supply channel 89 and a check valve 91 for opening and closing the hot water supply channel 89.

[0067] Furthermore, an air layer forming hopper 92 is interposed between the hot water filling solenoid valve 90 and the hot water filling check valve 91 in the hot water filling passage 89. The hopper 92 for forming an air layer is provided with a drainage channel 93 for draining hot water and an electromagnetic drain valve 94 for opening and closing the drainage channel 93. The end of the drainage channel 93 is connected to the point between the bath water circulation pump 84 and the water flow switch 87 in the bath water return channel 82. Since the configuration and function of the air layer forming hopper 92 are well known, a detailed explanation will be omitted in this embodiment.

[0068] Therefore, when the hot water supply solenoid valve 90 is opened, the hot water that has been heated in the hot water heating unit F and then supplied through the hot water supply passage 89 is supplied to the bath water return passage 82, and the hot water supplied to the bath water return passage 82 flows in a manner that divides towards both the side where the bathtub 50 is located and the side where the reheating heat exchanger 79 is located. In other words, the hot water supplied through the hot water supply passage 89 is supplied to the bathtub 50 through the bath water supply passage 83 and the bath water return passage 82.

[0069] External anti-freeze heaters Hb are provided in the hot and cold water flow path L inside the water heater B. Specifically, external anti-freeze heaters Hb are provided in the flow path upstream of the branching point of the water supply bypass path 68 in the inlet path 52, the flow path between the hot water heat exchanger 54 and the mixing valve 69 in the hot water supply path 53, the flow path between the mixing valve 69 and the branching point of the hot water supply path 89 in the hot water supply path 53, and the flow path downstream of the branching point of the hot water supply path 89 in the hot water supply path 53.

[0070] If the hot water control device Q determines, based on detection information from an outside temperature sensor (not shown), that there is a risk of freezing, it will activate five external anti-freeze heaters Hb to prevent the hot water inside the hot water flow path L of the water heater B from freezing. Incidentally, when fuel gas is not supplied, the hot water supply control device Q receives a heater hot water switching command, which instructs the start of heater-heated hot water supply processing. When this command is issued to perform the heater-heated hot water supply processing described later, the five external anti-freeze heaters Hb are activated.

[0071] Furthermore, a bath water heating heater Hy is provided in the downstream flow path portion of the reheating heat exchanger 79 in the bath water supply path 83 of the bath water circulation circuit K. The hot water supply control device Q is configured to heat the bath water by circulating it through the bath water circulation circuit K while the bath water heating heater Hy is activated after filling the bathtub with hot water using the heater-heated hot water supply process described later. The details of this process will be described later.

[0072] Incidentally, although not shown in the diagram, the five external anti-freeze heaters Hb, the bath water heating heater Hy, and the bath water circulation pump 84 are powered by the commercial power supply 6. In other words, the five external anti-freeze heaters Hb, the bathtub water heating heater Hy, and the bathtub water circulation pump 84 are designed to be powered by the commercial power supply 6 as an external power source, even when the power generation unit A is stopped.

[0073] (Operation control of water heaters) The water heater B is equipped with the above-mentioned devices, and as is clear from the above description, it is configured to perform a general hot water supply process, which supplies heated hot water to the hot water tap 38, and a bath filling process, which supplies heated hot water to the bathtub 50, as well as a heat medium supply process, which circulates and supplies heated heat medium to the heat consumption terminal 51, and a reheating process, which reheats the bathtub water in the bathtub 50.

[0074] In other words, the hot water control device Q is configured to operate the equipment installed in the water heater B based on command information from the remote control R and the bathroom remote control R2, and detection information from sensors installed in the water heater B, and when fuel gas is supplied, to perform general hot water supply operation corresponding to hot water supply processing, automatic hot water filling operation corresponding to hot water filling processing, keep operation performed following automatic hot water filling operation, additional hot water supply operation to fill the bathtub 50, terminal heating operation corresponding to heat transfer medium supply processing, and reheating operation corresponding to reheating processing.

[0075] Furthermore, when the hot water supply control device Q receives a heater hot water switching command that instructs the start of heater-heated hot water supply processing when fuel gas is not being supplied, it executes a process to activate five external anti-freeze heaters Hb as a process corresponding to heater-heated hot water supply processing. Furthermore, when a heater hot water switching command is issued to initiate heater-heated hot water supply, and when filling the bathtub is instructed, the system is configured to supply a set amount of hot water to the bathtub 50 using the heater-heated hot water supply. Subsequently, if the temperature of the bathtub water is lower than the set bathtub water temperature, the system is configured to operate the bathtub water circulation pump 84 with the bathtub water heating heater Hy activated to raise the temperature of the bathtub water, thereby executing a heater-type hot water filling process.

[0076] The following provides explanations for each operation: general hot water supply operation, terminal heating operation, automatic hot water filling operation, and reheating operation. Incidentally, in addition to these operations, as described later, when a heater-heated hot water supply switching command is issued to start heater-heated hot water supply while the fuel gas supply is stopped, the hot water supply control device Q executes the process corresponding to heater-heated hot water supply and the heater-type hot water filling process.

[0077] (Normal hot water supply operation) When fuel gas is supplied, the hot water supply control device Q performs general hot water supply operation when the hot water tap 38 is opened and the amount of water detected by the water volume sensor 67 exceeds a predetermined amount. In general hot water supply operation, after driving the hot water blower fan 56 in the hot water heating unit F, the intermittent valve 65 is opened and the hot water burner 55 is ignited by the igniter. Based on the water volume detected by the water volume sensor 67, the water temperature detected by the water supply thermistor 66, the temperature detected by the hot water outlet thermistor 70, and the temperature detected by the hot water thermistor 71, the opening of the gas proportional valve 64 and the opening of the mixing valve 69 are adjusted so that the temperature detected by the hot water thermistor 71 reaches the set target temperature (for example, 40°C). Then, when the water flow sensor 67 no longer detects water flow, the intermittent valve 65 is closed to stop the combustion of the hot water burner 55, the hot water blower fan 56 is stopped, and general hot water operation ends.

[0078] (Terminal heating operation) When fuel gas is supplied, the hot water supply control device Q executes terminal heating operation when it is instructed to start terminal heating operation. In terminal heating operation, the terminal thermal valve 76 is opened and the reheating thermal valve 80 is closed, and the heat medium circulation pump Jp is operated to circulate the heat medium through the heat medium circulation circuit J. Simultaneously, the heat medium blower fan 61 in the heat medium heating section G is driven, and then the intermittent valve 65 is opened to ignite the heat medium heating burner 60 with an igniter. Finally, the opening degree of the gas proportional valve 64 is adjusted so that the temperature detected by the heat medium thermistor 75 reaches the target circulation temperature (for example, 70°C).

[0079] (Automatic bath filling operation) The hot water supply control device Q is configured to perform automatic hot water filling operation when a hot water filling command is issued while fuel gas is being supplied. In automatic bath filling operation, the process of supplying hot water to the bathtub 50 and the process of stopping the supply of hot water and determining the water level detected by the water level sensor 86 are performed alternately until the water level detected by the water level sensor 86 is equal to or greater than the target water level. Once the water level detected by the water level sensor 86 is equal to or greater than the target water level, a reheating process is performed to reheat the bathtub water to the target bath filling temperature, after which the automatic bath filling operation ends.

[0080] During the hot water supply process, the hot water supply control device Q opens the hot water supply solenoid valve 90 and ignites the hot water burner 55 in the same manner as in the general hot water supply operation described above. Based on the water volume detected by the water volume sensor 67, the water temperature detected by the water supply thermistor 66, the temperature detected by the hot water outlet thermistor 70, and the temperature detected by the hot water supply thermistor 71, the Q adjusts the opening of the gas proportional valve 64 and the mixing valve 69 so that the temperature detected by the hot water supply thermistor 71 becomes the set target hot water supply temperature. After the set time for hot water supply has elapsed, the Q closes the hot water supply solenoid valve 90 and temporarily stops the combustion of the hot water burner 55 for the determination process described above.

[0081] Furthermore, in the reheating process, the hot water supply control device Q closes the terminal thermal valve 76 and opens the reheating thermal valve 80, then operates the heat medium circulation pump Jp and the bath water circulation pump 84 to circulate the hot water in the bath 50 through the bath water return path 82 and the bath water supply path 83. In conjunction with this, it drives the heat medium blower fan 61 in the heat medium heating section G, then opens the intermittent valve 65 to ignite the heat medium heating burner 60 with an igniter. In addition, it adjusts the opening degree of the gas proportional valve 64 so that the temperature detected by the bath supply temperature detection sensor 88 becomes the set hot water outlet temperature for reheating (for example, 60°C).

[0082] Then, when the temperature detected by the bath water temperature detection sensor 85 reaches or exceeds the target bath filling temperature, the intermittent valve 65 is closed to stop the combustion of the heat transfer medium heating burner 60, and the heat transfer medium blower fan 61 is stopped to end the reheating process.

[0083] (Reheating operation) When the hot water supply control device Q is instructed to start reheating operation, it operates the bath water circulation pump 84 with the drain valve 94 closed, and then, after a set elapsed time (for example, 10 seconds), it reads the temperature detected by the bath water temperature detection sensor 85.

[0084] If the temperature detected by the bath water temperature detection sensor 85 is lower than the target bath filling temperature, the terminal thermal valve 76 is closed and the reheating thermal valve 80 is opened, similar to the reheating process described above, and the heat medium circulation pump Jp and the bath water circulation pump 84 are operated to circulate the hot water in the bath 50 through the bath water return path 82 and the bath water supply path 83. At the same time, the heat medium blower fan 61 in the heat medium heating section G is driven, and then the intermittent valve 65 is opened to ignite the heat medium heating burner 60 with the igniter. Furthermore, the opening degree of the gas proportional valve 64 is adjusted so that the temperature detected by the bath supply temperature detection sensor 88 becomes the set hot water outlet temperature for reheating (for example, 60°C), thereby heating the bath water.

[0085] Then, when the temperature detected by the bath water temperature detection sensor 85 reaches or exceeds the target bath water temperature, the bath water heating continues for a set additional time (for example, 30 seconds) from that point onward. After that, the intermittent valve 65 is closed to stop the combustion of the heat transfer medium heating burner 60, and the heat transfer medium blower fan 61 is stopped to end the reheating operation.

[0086] (Details of heater-type hot water supply system) When fuel gas is not supplied, the operation control device C executes the heater-heated hot water supply process when it receives a heater-heated hot water supply switching command that instructs the start of the heater-heated hot water supply process. In other words, the power generation control device P operates the storage tank side freeze prevention heater H1 while the circulation pump 22 is running to raise the temperature of the hot water in the storage tank 3, and the hot water supply control device Q, when instructed to dispense hot water, that is, when the hot water tap 38 is opened and the amount of water detected by the water volume sensor 67 exceeds a predetermined amount, or when instructed to fill the tank with hot water, performs the process of raising the temperature of the hot water supplied from the tank using the external freeze prevention heater Hb and dispensing it.

[0087] In this embodiment, in a heater-heated hot water supply process, the power generation control device P controls the mixing valve 33 so that the temperature of the hot water supplied from the tank, which has been mixed with cold water, reaches a set supply temperature (for example, 35°C), or so that cold water is mixed with the hot water supplied from the tank at a set ratio. Furthermore, when the temperature of the hot water supplied from the tank, which has been mixed with cold water, that is, the temperature of the hot water supplied from the tank detected by the water supply thermistor 66, is lower than the set target temperature, the hot water supply control device Q activates five external anti-freeze heaters Hb to bring the temperature of the hot water supplied from the tank closer to the set target temperature (for example, 40°C).

[0088] Incidentally, in this embodiment, we illustrate a configuration in which all five external anti-freeze heaters Hb are activated simultaneously. However, it is also possible to adjust the amount of heating by the external anti-freeze heaters Hb by changing the number of heaters activated among the five external anti-freeze heaters Hb based on the difference between the temperature of the hot water supplied from the tank detected by the water supply thermistor 66 and the set target temperature.

[0089] (Details of the heater-type water filling process) The operation control device C is configured such that when fuel gas is not supplied, and a heater hot water switching command is issued to start heater-heated hot water supply, when a bath filling command is issued, it supplies a set amount of hot water to the bathtub 50 using the heater-heated hot water supply method. Subsequently, if the temperature of the bathtub water is lower than the set bath filling temperature, it operates the bathtub water heating heater Hy and drives the bathtub water circulation pump 84 to raise the temperature of the bathtub water, thereby executing a heater-type bath filling process.

[0090] In other words, the process of supplying hot water heated by a heater-type hot water supply system to the bathtub 50, and the process of stopping the hot water supply process and determining the water level detected by the water level sensor 86 are performed alternately, and this process is repeated until the water level detected by the water level sensor 86 reaches the target water level (an example of the set amount of hot water to fill). When the water level detected by the water level sensor 86 reaches or exceeds the target water level, the process of raising the temperature of the bathtub water to the set hot water filling temperature is performed.

[0091] During the hot water supply process, the hot water supply control device Q opens the hot water filling solenoid valve 90, and activates five external anti-freeze heaters Hb when the temperature of the hot water supplied to the tank, as detected by the water supply thermistor 66, is lower than the set hot water filling temperature.

[0092] Furthermore, when the hot water supply control device Q raises the temperature of the bath water to the set bath filling temperature, it operates the bath water heating heater Hy and drives the bath water circulation pump 84. When the temperature detected by the bath water temperature detection sensor 85 reaches or exceeds the set bath filling temperature, it stops the bath water heating heater Hy and the bath water circulation pump 84, and terminates the process.

[0093] (Details of control operation) Next, we will explain the control operation of the operation control device C, that is, the water temperature management control, when a heater hot water switching command is issued to start heater-heated hot water treatment when fuel gas is not supplied, based on the flowcharts in Figures 3 to 6. As shown in Figure 3, in the water temperature control, first, the process of raising the temperature inside the tank (#100) is executed, and when a hot water supply is instructed, that is, when a hot water supply operation is performed (#01 Yes), the process of raising the temperature during hot water supply (#200) is executed.

[0094] Furthermore, when a bathtub filling operation is instructed, that is, when a bathtub filling operation is performed (#02 Yes), the bathtub hot water supply process equivalent to a heater-type bathtub filling process is executed (#300). Subsequently, if it is determined that the process is complete when fuel gas is supplied or when a heater hot water switching command is issued to stop the heater-heated hot water treatment (#3 Yes), the hot water temperature control process is terminated. If it is determined that the process is not complete (#3 No), the process proceeds to #100.

[0095] [Process for raising the temperature inside the tank] As shown in Figure 4, in the tank temperature raising process (#100), the tank temperature is obtained based on the detection information from the cold water side sensor 25 (#101). If the obtained temperature is less than the set value corresponding to the target temperature (e.g., 70°C) (No. in #102), the process of driving the circulation pump 22 (#103) and the process of turning on the heater to activate the hot water side freeze prevention heater H1 (#104) are executed, and then the process proceeds to the flowchart shown in Figure 3.

[0096] Based on the detection information from the cold water side sensor 25, if it is determined that the temperature inside the tank has reached a set value or higher (Yes in #102), the process of stopping the hot water side freeze prevention heater H1 (Heater OFF process, #105) and stopping the circulation pump 22 (Circulation pump, #106) is executed, and then the process proceeds to the flowchart shown in Figure 3.

[0097] [Processing for raising the temperature during hot water supply] As shown in Figure 5, in the process of raising the temperature during hot water supply (step #200), the mixing valve 33 is controlled so that the temperature of the hot water supplied from the tank, which has been mixed with cold water, reaches the set supply temperature (for example, 35°C), or the mixing valve 33 is controlled so that cold water is mixed with the hot water supplied from the tank at a set ratio, and the process of starting hot water supply is executed to supply the hot water to the water heater B (step #201). Subsequently, the process of obtaining the temperature detected by the water supply thermistor 66 as the hot water supply temperature is executed (step #202).

[0098] The system determines whether the hot water temperature is below the set target temperature (#203). If it is below the set target, it performs a heater ON process to activate the five external anti-freeze heaters Hb (#204). If it is not below the set target, it performs a heater OFF process to stop the five external anti-freeze heaters Hb (#205). After that, the system proceeds to the flowchart shown in Figure 3.

[0099] [Bathtub hot water supply treatment] As shown in Figure 6, in the bathtub hot water supply process (#300 step), the mixing valve 33 is controlled so that the temperature of the tank-discharged hot water mixed with cold water reaches the set supply temperature (for example, 35°C), or the mixing valve 33 is controlled so that cold water is mixed with the tank-discharged hot water at a set ratio, and the tank-discharged hot water is supplied to the water heater B, and the process of opening the hot water filling solenoid valve 90 to start discharging hot water is executed (#301), followed by the process of obtaining the temperature detected by the water supply thermistor 66 as the hot water discharge temperature (#302).

[0100] Subsequently, the system determines whether the hot water temperature is below the set value for the set bath filling temperature (#303). If it is below the set value, the system performs a heater ON process to activate the five external anti-freeze heaters Hb (#304). If it is not below the set value, the system performs a heater OFF process to stop the five external anti-freeze heaters Hb (#305).

[0101] Next, the system determines whether the water level detected by the judgment process described above is the target water level (an example of the set amount of hot water to be filled) (#306). If the water level is above the target water level, the system closes the solenoid valve 90 and stops the hot water supply (#307). Next, the process of acquiring the temperature detected by the bath water temperature detection sensor 85, which is detected while the bath water circulation pump 84 is running, as the bath water temperature is executed (#308), and then it is determined whether or not the bath water temperature is equal to or greater than the set value for the set bath filling temperature (#309).

[0102] If process #309 determines that the bath water temperature is not above the set value, the process to turn on the bath water heating heater Hy (#310) and the process to drive the bath water circulation pump 84 (#311) are executed, after which the process proceeds to process #308.

[0103] If the #309 process determines that the bath water temperature is above the set value, the bath water circulation pump stop and heater OFF process is executed (#312), stopping the bath water circulation pump 84 and the bath water heating heater Hy. After that, the process proceeds to the flowchart shown in Figure 3.

[0104] [Another embodiment] In the above embodiment, the operation control device C controls the mixing valve 33 in a heater-heated hot water supply process so that the temperature of the hot water discharged from the tank, mixed with cold water, reaches a set supply temperature (for example, 35°C), or so that cold water is mixed with the hot water discharged from the tank at a set ratio. Furthermore, when the temperature of the hot water discharged from the tank, mixed with cold water, is lower than the set target temperature, the external anti-freeze heater Hb is activated to bring the temperature of the hot water discharged from the tank closer to the set target temperature.

[0105] As an alternative form of heater-heated hot water supply treatment, the operation control device C may operate the external freeze prevention heater Hb and control the mixing valve 33 to adjust the temperature of the tank-discharged hot water mixed with cold water so that the estimated outlet temperature of the hot water dispensed from the water heater B becomes the set target temperature. In other words, the estimated hot water outlet temperature is the sum of the temperature detected by the downstream temperature sensor 36 and the set temperature increase that is expected to occur when the external anti-freeze heater Hb is used to raise the temperature. The mixing valve 33 is controlled to adjust the temperature of the hot water sent to the tank, to which cold water is mixed, so that the estimated hot water outlet temperature becomes the set target temperature. In this configuration, the external anti-freeze heater Hb is activated in a unambiguous manner in heater-heated hot water supply processing.

[0106] Furthermore, as an alternative form of heater-heated hot water supply treatment, the operation control device C may control the mixing valve 33 to adjust the temperature of the tank-discharged hot water mixed with cold water to a temperature such that the estimated discharge temperature of the hot water dispensed from the water heater B becomes the set target temperature, assuming that the external anti-freeze heater Hb is activated. In addition, if the temperature of the tank-discharged hot water mixed with cold water is lower than the set target temperature, the external anti-freeze heater Hb may be activated to bring the temperature of the tank-discharged hot water closer to the set target temperature.

[0107] In other words, the estimated hot water outlet temperature is the sum of the temperature detected by the downstream temperature sensor 36 and the set temperature increase that is expected to occur when the external anti-freeze heater Hb is activated. The mixing valve 33 is controlled to adjust the temperature of the hot water sent to the tank, to which cold water is mixed, so that the estimated hot water outlet temperature becomes the set target temperature. Furthermore, if the temperature of the tank-discharged hot water mixed with chilled water, as detected by the water supply thermistor 66, is lower than the set target temperature, the external freeze prevention heater Hb is activated to bring the temperature of the tank-discharged hot water closer to the set target temperature.

[0108] Incidentally, assuming that the external anti-freeze heaters Hb are activated, it is also possible to predict the set temperature rise by assuming that some (for example, 3) of the multiple (5) external anti-freeze heaters Hb are activated, and then, when activating the external anti-freeze heaters Hb to bring the temperature of the hot water supplied to the tank closer to the set target temperature, the number of heaters activated out of the 5 external anti-freeze heaters Hb is controlled based on the temperature difference between the temperature of the hot water supplied to the tank and the set target temperature, so as to bring the temperature of the hot water supplied to the tank closer to the set target temperature.

[0109] [Other embodiments] (a) In the above embodiment, an example was given in which the circulation pump 22 is driven under preset drive conditions in a heater-heated hot water supply treatment. However, the operation of the circulation pump 22 may also be controlled in a manner that adjusts the amount of hot water circulating through the circulation path 20 so that the temperature of the hot water heated by the storage-side anti-freeze heater H1, that is, the temperature of the hot water supplied to the upper part of the storage tank 3 through the circulation path 20, reaches a target temperature (for example, 70°C).

[0110] (b) In the above embodiment, when supplying a set amount of hot water to the bathtub 50 using the heater-type hot water supply process, the example given was that the water level detected by the water level sensor 86 is controlled to reach the target water level. However, for example, a flow meter may be installed in the hot water supply passage 89, and it may be determined that the set amount of hot water has been supplied to the bathtub 50 when the total flow rate detected by the flow meter after the start of hot water supply reaches a flow rate corresponding to the set amount of hot water supply.

[0111] (c) In the above embodiment, an example was given in which five external anti-freeze heaters Hb are provided, but the number of external anti-freeze heaters Hb and their installation locations can be changed in various ways depending on the specific configuration of the water heater B.

[0112] (d) In the above embodiment, the example given for the water heater B is one in which the bath water circulation circuit K is connected to the reheating heat exchanger 79 to which the heat medium is supplied from the heat medium circulation circuit J. However, the specific configuration of the water heater B can be changed in various ways, for example, by configuring the bath water circulation circuit K to be connected to the heat exchange section heated by the reheating burner.

[0113] (e) The current supplied to the storage-side antifreeze heater H1 and the external antifreeze heater Hb may be set such that the current supplied when heating the hot water is greater than the current supplied for antifreeze, thereby increasing the heating capacity when heating the hot water to a greater level than the heating capacity when performing antifreeze.

[0114] (f) In the above embodiment, when fuel gas is not supplied, a heater hot water supply switching command is issued from the remote control R to command the start of heater hot water supply, and the heater hot water supply is executed as an example. However, the system may be implemented in a way that the heater hot water supply is automatically executed when it is detected that fuel gas is not being supplied.

[0115] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Industrial applicability]

[0116] This invention can be used in an energy supply system that generates electricity in a power generation unit using supplied fuel gas and stores hot water heated by the waste heat generated during power generation in a hot water storage tank. [Explanation of Symbols]

[0117] 2 Heat exchange section 3. Hot water storage tank 20 Heat exchange channel 22 Circulation pump 33 Mixing valve 50 Bathtubs 84 Bathtub water circulation pump B Water heater C Driving control device M Power Generation Department H1 Anti-freeze heater for hot water storage side Hb External freeze protection heater Hy Bathtub Water Heater K circulation channel L Hot water flow path

Claims

1. An energy supply system comprising: a fuel cell type power generation unit that generates electricity by supplying fuel gas; a hot water tank that stores hot water; a heat exchange flow path that circulates the hot water in the hot water tank by a circulation pump through a heat exchange unit that transfers heat generated by power generation in the power generation unit; a water heater that heats the tank-delivery hot water supplied from the hot water storage tank with the combustion heat of the fuel gas and supplies the water; and an operation control unit, A hot water storage side anti-freeze heater is provided in the heat exchange flow path, and an external anti-freeze heater is provided in the hot water flow path inside the water heater, The operation control unit, when the fuel gas is not supplied, operates the hot water storage side anti-freeze heater while driving the circulation pump to heat the hot water in the hot water storage tank, and when hot water is instructed to be dispensed, performs a heater-heated hot water supply process in which the hot water dispensed from the tank is heated by the external anti-freeze heater and dispensed.

2. A mixing valve is provided to mix cold water with the hot water delivered from the tank, The energy supply system of claim 1, wherein the operation control unit controls the mixing valve in the heater-heated hot water supply process so that the temperature of the hot water delivered to the tank mixed with the cold water becomes a set supply temperature or so that the cold water is mixed with the hot water delivered to the tank at a set ratio, and when the temperature of the hot water delivered to the tank mixed with the cold water is lower than the set target temperature, the external anti-freeze heater is activated to bring the temperature of the hot water delivered to the tank closer to the set target temperature.

3. A mixing valve is provided to mix cold water with the hot water delivered from the tank, The energy supply system described in claim 1, wherein the operation control unit activates the external anti-freeze heater during the heater-heated hot water supply process and controls the mixing valve to adjust the temperature of the hot water discharged from the tank mixed with the cold water to a temperature at which the estimated outlet temperature of the hot water discharged from the water heater becomes the set target temperature.

4. A mixing valve is provided to mix cold water with the hot water delivered from the tank, The energy supply system described in claim 1, wherein the operation control unit controls the mixing valve to adjust the temperature of the hot water discharged from the tank mixed with the cold water in the heater-heated hot water supply process to a temperature at which the estimated outlet temperature of the hot water discharged from the water heater becomes the set target temperature when the external anti-freeze heater is activated, and when the temperature of the hot water discharged from the tank mixed with the cold water is lower than the set target temperature, activates the external anti-freeze heater to bring the temperature of the hot water discharged from the tank closer to the set target temperature.

5. A bathtub water heater is provided in a circulation flow path that circulates bathwater between the bathtub to which hot water is supplied from the water heater and the water heater using a bathtub water circulation pump; The energy supply system described in any one of claims 1 to 4, wherein when a filling command is received, the operation control unit supplies the bathtub with a set amount of hot water to be dispensed by the heater-heated hot water supply process, and then, when the temperature of the bathtub water is lower than the set filling temperature, executes a heater-type filling process to raise the temperature of the bathtub water by driving the bathtub water circulation pump with the bathtub water heating heater activated.

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