US20200408442A1 - Water heating apparatus and water heating system - Google Patents

Water heating apparatus and water heating system Download PDF

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Publication number
US20200408442A1
US20200408442A1 US16/907,128 US202016907128A US2020408442A1 US 20200408442 A1 US20200408442 A1 US 20200408442A1 US 202016907128 A US202016907128 A US 202016907128A US 2020408442 A1 US2020408442 A1 US 2020408442A1
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Prior art keywords
hot water
temperature
water supply
combustion
controller
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US16/907,128
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English (en)
Inventor
Takahide Hasegawa
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Noritz Corp
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Noritz Corp
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Publication of US20200408442A1 publication Critical patent/US20200408442A1/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D17/00Domestic hot-water supply systems
    • F24D17/0078Recirculation systems
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/10Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium
    • F24H1/107Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using fluid fuel
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/20Arrangement or mounting of control or safety devices
    • F24H9/2007Arrangement or mounting of control or safety devices for water heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23NREGULATING OR CONTROLLING COMBUSTION
    • F23N5/00Systems for controlling combustion
    • F23N5/02Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/022Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using electronic means
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D19/00Details
    • F24D19/10Arrangement or mounting of control or safety devices
    • F24D19/1006Arrangement or mounting of control or safety devices for water heating systems
    • F24D19/1051Arrangement or mounting of control or safety devices for water heating systems for domestic hot water
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/10Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/10Control of fluid heaters characterised by the purpose of the control
    • F24H15/104Inspection; Diagnosis; Trial operation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/10Control of fluid heaters characterised by the purpose of the control
    • F24H15/174Supplying heated water with desired temperature or desired range of temperature
    • F24H15/175Supplying heated water with desired temperature or desired range of temperature where the difference between the measured temperature and a set temperature is kept under a predetermined value
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/20Control of fluid heaters characterised by control inputs
    • F24H15/212Temperature of the water
    • F24H15/215Temperature of the water before heating
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/20Control of fluid heaters characterised by control inputs
    • F24H15/212Temperature of the water
    • F24H15/219Temperature of the water after heating
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/20Control of fluid heaters characterised by control inputs
    • F24H15/238Flow rate
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/30Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
    • F24H15/305Control of valves
    • F24H15/31Control of valves of valves having only one inlet port and one outlet port, e.g. flow rate regulating valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/30Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
    • F24H15/305Control of valves
    • F24H15/325Control of valves of by-pass valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/30Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
    • F24H15/335Control of pumps, e.g. on-off control
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/30Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
    • F24H15/355Control of heat-generating means in heaters
    • F24H15/37Control of heat-generating means in heaters of electric heaters
    • F24H9/128
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/12Arrangements for connecting heaters to circulation pipes
    • F24H9/13Arrangements for connecting heaters to circulation pipes for water heaters
    • F24H9/139Continuous flow heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/18Arrangement or mounting of grates or heating means
    • F24H9/1809Arrangement or mounting of grates or heating means for water heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/20Arrangement or mounting of control or safety devices
    • F24H9/2007Arrangement or mounting of control or safety devices for water heaters
    • F24H9/2035Arrangement or mounting of control or safety devices for water heaters using fluid fuel
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00Control of temperature
    • G05D23/19Control of temperature characterised by the use of electric means
    • G05D23/1927Control of temperature characterised by the use of electric means using a plurality of sensors
    • G05D23/193Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces
    • G05D23/1931Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces to control the temperature of one space
    • EFIXED CONSTRUCTIONS
    • E03WATER SUPPLY; SEWERAGE
    • E03BINSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
    • E03B7/00Water main or service pipe systems
    • E03B7/04Domestic or like local pipe systems
    • E03B7/045Domestic or like local pipe systems diverting initially cold water in warm water supply
    • EFIXED CONSTRUCTIONS
    • E03WATER SUPPLY; SEWERAGE
    • E03CDOMESTIC PLUMBING INSTALLATIONS FOR FRESH WATER OR WASTE WATER; SINKS
    • E03C1/00Domestic plumbing installations for fresh water or waste water; Sinks
    • E03C1/02Plumbing installations for fresh water
    • E03C1/04Water-basin installations specially adapted to wash-basins or baths
    • E03C1/0411Taps specially designed for dispensing boiling water
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23NREGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00Measuring
    • F23N2225/08Measuring temperature
    • F23N2225/18Measuring temperature feedwater temperature
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23NREGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00Measuring
    • F23N2225/08Measuring temperature
    • F23N2225/19Measuring temperature outlet temperature water heat-exchanger
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D17/00Domestic hot-water supply systems
    • F24D17/0073Arrangements for preventing the occurrence or proliferation of microorganisms in the water
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D17/00Domestic hot-water supply systems
    • F24D17/0078Recirculation systems
    • F24D17/0084Coaxial tubings
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D2200/00Heat sources or energy sources
    • F24D2200/04Gas or oil fired boiler
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D2220/00Components of central heating installations excluding heat sources
    • F24D2220/04Sensors
    • F24D2220/042Temperature sensors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D2220/00Components of central heating installations excluding heat sources
    • F24D2220/04Sensors
    • F24D2220/044Flow sensors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/20Control of fluid heaters characterised by control inputs
    • F24H15/269Time, e.g. hour or date
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H15/00Control of fluid heaters
    • F24H15/30Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
    • F24H15/395Information to users, e.g. alarms

Definitions

  • the present disclosure relates to a water heating apparatus and a water heating system and more particularly to a water heating apparatus and a water heating system both with an immediate hot water supply function.
  • a water heating apparatus of one form is equipped with what is called an immediate hot water supply function for outputting hot water at an appropriate temperature immediately after start of hot water supply even after hot water supply has been off for a long period of time.
  • an immediate hot water supply operation mode Normally, in order to achieve the immediate hot water supply function, a mode in which a circulation path that goes through a heat source also while hot water supply is off is formed (an “immediate hot water supply operation mode” below) should be provided.
  • U.S. Pat. No. 6,536,464 discloses a configuration for forming a circulation path for the immediate hot water supply function by externally connecting a bypass valve (which is also referred to as a “crossover valve” below) for thermostatic control using a wax thermostatic element.
  • the immediate hot water supply function can thus be achieved by simplified attachment works without adding a function to control the crossover valve on a side of the water heating apparatus.
  • Japanese Patent Laying-Open No. 2015-230151 also describes a configuration in which an immediate hot water supply operation is performed by using a path to which a thermal valve similar to the crossover valve is connected.
  • a combustion mechanism such as a combustion burner as a heat source
  • difficulty in temperature control by adjustment of a quantity of heat generated by the combustion mechanism (an amount of fuel that is burnt).
  • the present disclosure was made to solve such problems, and an object of the present disclosure is to stabilize an operation with simplified temperature control in an immediate hot water supply operation mode by using a circulation path to which a crossover valve is connected.
  • the water heating apparatus further includes an inner path.
  • the inner path forms an immediate hot water supply circulation path through which fluid passes through the heating mechanism, as being combined with an outer path, the outer path bypassing the hot water supply faucet on the outside of the water heating apparatus.
  • the outer path includes a thermal water stop bypass valve including a path that is closed when a temperature increases.
  • the first temperature detector detects a fluid temperature upstream from the heating mechanism in the immediate hot water supply circulation path.
  • the second temperature detector detects a fluid temperature downstream from the heating mechanism in the immediate hot water supply circulation path.
  • the flow rate detector detects a circulation flow rate in the immediate hot water supply circulation path.
  • the controller controls the heating mechanism and the circulation pump.
  • the controller includes a heat quantity controller and a combustion controller.
  • the heat quantity controller sets, in the immediate hot water supply operation mode, an output heat quantity command value for the combustion mechanism for controlling a temperature detection value detected by the second temperature detector to a set temperature in the immediate hot water supply operation mode.
  • the combustion controller controls the combustion mechanism in accordance with the output heat quantity command value.
  • the output heat quantity command value is set as being restricted within a range from a minimum heat quantity value to a maximum heat quantity value in a combustion state of the combustion mechanism.
  • the combustion controller controls the combustion mechanism in the immediate hot water supply operation mode so as to alternately provide a minimum combustion state and a combustion stop state when the output heat quantity command value is set to the minimum heat quantity value and when the temperature detection value detected by the second temperature detector increases to a control upper limit temperature set to be higher than the set temperature. In the minimum combustion state, the combustion mechanism operates in accordance with the minimum heat quantity value.
  • a water heating system includes a water heating apparatus including a water entry port and a hot water output port, a low-temperature water pipe that introduces low-temperature water to the water entry port, a high-temperature water pipe that connects the hot water output port and a hot water supply faucet to each other, and a circulation pump arranged inside or outside the water heating apparatus.
  • the water heating apparatus includes a heating mechanism including a combustion mechanism, a first temperature detector, a second temperature detector, a flow rate detector, and a controller.
  • the water heating apparatus further includes an inner path.
  • the inner path forms an immediate hot water supply circulation path through which fluid passes through the heating mechanism, as being combined with an outer path, the outer path bypassing the hot water supply faucet on the outside of the water heating apparatus.
  • the outer path includes a thermal water stop bypass valve including a path that is closed when a temperature increases.
  • the first temperature detector detects a fluid temperature upstream from the heating mechanism in the immediate hot water supply circulation path.
  • the second temperature detector detects a fluid temperature downstream from the heating mechanism in the immediate hot water supply circulation path.
  • the flow rate detector detects a circulation flow rate in the immediate hot water supply circulation path.
  • the controller controls the heating mechanism and the circulation pump.
  • the controller includes a heat quantity controller and a combustion controller.
  • the heat quantity controller sets, in the immediate hot water supply operation mode, an output heat quantity command value for the combustion mechanism for controlling a temperature detection value detected by the second temperature detector to a set temperature in the immediate hot water supply operation mode.
  • the combustion controller controls the combustion mechanism in accordance with the output heat quantity command value.
  • the output heat quantity command value is set as being restricted within a range from a minimum heat quantity value to a maximum heat quantity value in a combustion state of the combustion mechanism.
  • the combustion controller controls the combustion mechanism in the immediate hot water supply operation mode so as to alternately provide a minimum combustion state and a combustion stop state when the output heat quantity command value is set to the minimum heat quantity value and when the temperature detection value detected by the second temperature detector increases to a control upper limit temperature set to be higher than the set temperature. In the minimum combustion state, the combustion mechanism operates in accordance with the minimum heat quantity value.
  • FIG. 1 is a block diagram illustrating a configuration of a water heating system including a water heating apparatus according to the present embodiment.
  • FIG. 2 is a block diagram illustrating an exemplary hardware configuration of a controller.
  • FIG. 3 shows a chart illustrating switching between flow paths by means of a crossover valve shown in FIG. 1 .
  • FIG. 4 shows a state transition diagram involved with an immediate hot water supply operation by the water heating apparatus according to the present embodiment.
  • FIG. 5 is a block diagram illustrating temperature control in an immediate hot water supply operation mode.
  • FIG. 6 shows an exemplary operation waveform diagram of temperature control in the immediate hot water supply operation mode.
  • FIG. 7 is a flowchart illustrating control processing for determining whether or not a condition for deactivating the immediate hot water supply operation mode is satisfied.
  • FIG. 8 is a flowchart illustrating control processing for determining whether or not a condition for resuming the immediate hot water supply operation mode is satisfied.
  • FIG. 9 is a flowchart illustrating control processing in diagnosis as to an abnormal condition of an immediate hot water supply circulation path performed in the immediate hot water supply operation mode.
  • FIG. 10 is a block diagram illustrating a configuration of a water heating apparatus and a water heating system according to a modification of the present embodiment.
  • FIG. 1 is a block diagram illustrating a configuration of a water heating system 1 A including a water heating apparatus according to the present embodiment.
  • water heating system 1 A includes a water heating apparatus 100 , a low-temperature water pipe 110 , a high-temperature water pipe 120 , and a crossover valve 200 .
  • Water heating apparatus 100 includes a water entry port 11 , a hot water output port 12 , and a circulation port 13 .
  • Low-temperature water pipe 110 is supplied with low-temperature water through a check valve 112 .
  • Low-temperature water is representatively supplied from a not-shown water supply pipe.
  • Low-temperature water pipe 110 is connected to water entry port 11 and circulation port 13 .
  • Water heating apparatus 100 includes a controller 10 , a water entry path 20 , a hot water output path 25 , a circulation path 28 , a bypass path 29 , a combustion mechanism 30 , a heat exchanger 40 , a circulation pump 80 , and a flow rate regulation valve 90 .
  • Water entry path 20 is formed between water entry port 11 and an input side (upstream side) of heat exchanger 40 with a check valve 21 being interposed.
  • Combustion mechanism 30 is representatively implemented by a burner that generates a quantity of heat by combustion of fuel such as gas or petroleum or the like.
  • Heat exchanger 40 increases a temperature of low-temperature water (fluid) introduced through water entry path 20 by using the quantity of heat generated by combustion mechanism 30 .
  • Combustion mechanism 30 and heat exchanger 40 implement an embodiment of the “heating mechanism.”
  • Hot water output path 25 is formed between an output side (downstream side) of heat exchanger 40 and hot water output port 12 .
  • Bypass path 29 connects water entry path 20 and hot water output path 25 to each other without heat exchanger 40 being interposed.
  • a ratio of a flow rate in bypass path 29 (a bypass flow rate ratio) to a total flow rate (the sum of a flow rate in heat exchanger 40 and a flow rate in bypass path 29 ) can be regulated.
  • some of low-temperature water bypasses heat exchanger 40 and is mixed without being heated, in a portion downstream from heat exchanger 40 , and thus high-temperature water is supplied from hot water output port 12 . Since a temperature of output from heat exchanger 40 (heating mechanism) can thus be high, drainage water generated by cooling of exhaust from combustion mechanism 30 at a surface of heat exchanger 40 is advantageously suppressed.
  • a flow rate sensor 81 that outputs a value of a flow rate of low-temperature water is arranged in water entry path 20 and a flow rate sensor 82 is arranged in circulation path 28 . Detection values from flow rate sensors 81 and 82 are input to controller 10 . Flow rate sensor 81 is arranged to be included in an immediate hot water supply circulation path which will be described later.
  • a temperature sensor 71 is arranged in hot water output path 25 and a temperature sensor 73 is arranged in water entry path 20 .
  • a temperature sensor 72 is arranged in circulation path 28 . Fluid temperatures detected by temperature sensors 71 to 73 are input to controller 10 .
  • a temperature sensor that detects a temperature of incogning water during a hot water supply operation is arranged also in water entry path 20 .
  • Temperature sensor 72 arranged upstream from heat exchanger 40 corresponds to an embodiment of the “first temperature detector” and temperature sensor 71 arranged downstream from heat exchanger 40 corresponds to an embodiment of the “second temperature detector.”
  • FIG. 2 is a block diagram illustrating an exemplary hardware configuration of controller 10 .
  • controller 10 is representatively implemented by a microcomputer.
  • Controller 10 includes a central processing unit (CPU) 15 , a memory 16 , an input and output (I/O) circuit 17 , and an electronic circuit 18 .
  • CPU 15 , memory 16 , and I/O circuit 17 can transmit and receive signals to one another through a bus 19 .
  • Electronic circuit 18 is configured to perform prescribed operation processing with dedicated hardware. Electronic circuit 18 can transmit and receive signals to and from CPU 15 and I/O circuit 17 .
  • CPU 15 receives output signals (detection values) from sensors including temperature sensors 71 to 73 and flow rate sensors 81 and 82 through I/O circuit 17 .
  • CPU 15 further receives a signal indicating an operation instruction input to a remote controller 92 through I/O circuit 17 .
  • the operation instruction includes, for example, an operation to switch on and off an operation switch of water heating apparatus 100 , a set hot water supply temperature, and various types of programmed time setting (which is also referred to as “timer setting”).
  • CPU 15 controls operations by constituent apparatuses including combustion mechanism 30 and circulation pump 80 such that water heating apparatus 100 operates in accordance with the operation instruction.
  • CPU 15 can output visually or aurally recognizable information by controlling a notification apparatus 95 .
  • notification apparatus 95 can output information by showing visually recognizable information such as characters and graphics on a screen.
  • notification apparatus 95 can be implemented by a display screen provided in remote controller 92 .
  • notification apparatus 95 may be implemented by a speaker so that information can also be output by voice and immediate sound or melodies.
  • low-temperature water is introduced into water entry path 20 by a supply pressure of low-temperature water.
  • flow rate sensor 81 detects a flow rate exceeding a minimum operating quantity (MOQ) of working water while the operation switch of water heating apparatus 100 is on, controller 10 activates combustion mechanism 30 .
  • MOQ minimum operating quantity
  • high-temperature water heated by combustion mechanism 30 and heat exchanger 40 is mixed with low-temperature water that passes through bypass path 29 and thereafter output from high-temperature water pipe 120 through hot water output port 12 .
  • controller 10 deactivates circulation pump 80 and controls a temperature of fluid (hot water output temperature Th) detected by temperature sensor 71 to a set hot water supply temperature input to remote controller 92 .
  • a temperature of hot water output can be controlled based on combination of control of a quantity of heating (a quantity of generated heat) by combustion mechanism 30 (heating mechanism) and control of the bypass flow rate ratio by means of flow rate regulation valve 90 .
  • Circulation path 28 is formed between circulation port 13 and water entry path 20 (a connection point 22 ).
  • Circulation pump 80 is connected to circulation path 28 .
  • circulation pump 80 may be connected to circulation port 13 on the outside of water heating apparatus 100 . Activation and deactivation of circulation pump 80 are controlled by controller 10 .
  • water heating apparatus 100 is provided with an immediate hot water supply function for promptly supplying high-temperature water after start of the hot water supply operation.
  • the immediate hot water supply function is performed by forming an immediate hot water supply circulation path including combustion mechanism 30 and heat exchanger 40 by activation of circulation pump 80 while the faucet is closed, that is, while hot water supply faucet 330 is closed.
  • a user can designate by timer setting, a period for which the immediate hot water supply operation is to be performed.
  • Timer setting can be input, for example, by operating remote controller 92 .
  • the period for which the immediate hot water supply operation is to be performed may automatically be set based on learning of a history of use by the user in the past.
  • the period for which the immediate hot water supply operation is performed can also be started or ended directly in response to a switch operation by the user.
  • crossover valve 200 In water heating system 1 A, the immediate hot water supply operation mode with activation of circulation pump 80 can be executed by using crossover valve 200 .
  • Crossover valve 200 is configured similarly to the thermostatically controlled bypass valve described in U.S. Pat. No. 6,536,464 and includes ports 201 to 204 and a wax thermostatic element 210 .
  • Ports 201 and 203 internally communicate with each other and ports 202 and 204 internally communicate with each other.
  • Wax thermostatic element 210 is connected between ports 201 and 203 and ports 202 and 204 .
  • Wax thermostatic element 210 forms a thermal bypass path between ports 201 and 203 and ports 202 and 204 in a low-temperature state. Wax thermostatic element 210 closes the thermal bypass path owing to thermal expansion force in a high-temperature state.
  • a switching temperature at which switching between formation and closing of the thermal bypass path is made is designed in advance depending on a material and a configuration of wax thermostatic element 210 .
  • a state that a fluid temperature in crossover valve 200 is higher than the switching temperature is also referred to as a high-temperature state and a state that the fluid temperature is lower than the switching temperature is also referred to as a low-temperature state below.
  • Crossover valve 200 thus corresponds to an embodiment of the “thermal water stop bypass valve.”
  • a pressure loss in the thermal bypass path is designed to be higher than a pressure loss in each of a path through which ports 201 and 203 communicate with each other and a path through which ports 202 and 204 communicate with each other.
  • Port 201 is connected to high-temperature water pipe 120 and port 202 is connected to low-temperature water pipe 110 .
  • Ports 203 and 204 are connected to hot water supply faucet 330 .
  • Hot water supply faucet 330 is provided as a combination faucet in which high-temperature water from port 203 and low-temperature water from port 204 are mixed.
  • Valves 331 and 332 for adjustment of a ratio of mixing between high-temperature water and low-temperature water can be provided between port 204 and hot water supply faucet 330 and between port 203 and hot water supply faucet 330 , respectively.
  • FIG. 3 shows a chart illustrating switching between flow paths by means of crossover valve 200 shown in FIG. 1 .
  • a thermal bypass path Pc is formed between ports 201 and 202 , that is, between high-temperature water pipe 120 and low-temperature water pipe 110 , through a thermal bypass path formed in wax thermostatic element 210 .
  • the thermal bypass path is closed so that the flow path between high-temperature water pipe 120 and low-temperature water pipe 110 is cut off.
  • high-temperature water is obtained by heating of low-temperature water introduced into water entry port 11 through low-temperature water pipe 110 by combustion mechanism 30 and heat exchanger 40 (heating mechanism). High-temperature water is output from hot water supply faucet 330 through hot water output port 12 and high-temperature water pipe 120 as well as crossover valve 200 (flow path Pa).
  • a fluid path (outer path) from hot water output port 12 through high-temperature water pipe 120 , crossover valve 200 (thermal bypass path Pc), and low-temperature water pipe 110 to circulation port 13 can be formed on the outside of water heating apparatus 100 .
  • a fluid path (an inner path) including circulation port 13 , circulation path 28 , water entry path 20 (on the downstream side of connection point 22 ), heat exchanger 40 (heating mechanism), hot water output path 25 , and hot water output port 12 can be formed.
  • the immediate hot water supply circulation path By forming the immediate hot water supply circulation path by the inner path and the outer path as such, high-temperature water flows through the immediate hot water supply circulation path also while the faucet is closed, so that high-temperature water can be supplied to hot water supply faucet 330 from immediately after the faucet is opened.
  • temperature sensor 72 can detect a fluid temperature (a return temperature Tb) before heating and temperature sensor 71 can detect a fluid temperature (hot water output temperature Th) after heating.
  • FIG. 4 shows a state transition diagram involved with the immediate hot water supply operation by water heating apparatus 100 . State transition shown in FIG. 4 is controlled by controller 10 .
  • controller 10 has water heating apparatus 100 make transition from an “immediate hot water supply operation off mode” to an “immediate hot water supply operation on mode.”
  • controller 10 determines that a start condition J 0 is satisfied and activates circulation pump 80 .
  • the immediate hot water supply operation mode is thus started.
  • controller 10 deactivates circulation pump 80 and starts a stand-by mode.
  • the hot water supply interrupt condition is satisfied with increase in value of the flow rate detected by flow rate sensor 81 .
  • controller 10 quits the stand-by mode and resumes a circulation operation mode.
  • the period for which the immediate hot water supply operation is to be performed ends based on timer setting or in response to a switch operation in the stand-by mode
  • water heating apparatus 100 returns to the immediate hot water supply operation off mode.
  • transition to the stand-by mode is made and thereafter water heating apparatus 100 returns to the immediate hot water supply operation off mode.
  • the fluid temperature in the immediate hot water supply circulation path can be increased. Therefore, the temperature in the immediate hot water supply circulation path is controlled by controlling an operation of combustion mechanism 30 in the immediate hot water supply operation mode.
  • crossover valve 200 included in the immediate hot water supply circulation path a pressure loss in the thermal bypass path caused by wax thermostatic element 210 is high. Therefore, since the flow rate of circulating fluid that passes through heat exchanger 40 is low in the immediate hot water supply operation mode, an amount of increase in temperature of fluid with respect to a quantity of heat generated by combustion mechanism 30 is large. On the other hand, from a point of view of ensuring stable combustion, reduction in quantity of heat generated by combustion mechanism 30 is limited. Consequently, even though the quantity of heat generated by combustion mechanism 30 is controlled to the minimum value, there is a concern about excessive heating and resultant instability in temperature control.
  • FIG. 5 is a block diagram illustrating temperature control in the immediate hot water supply operation mode.
  • controller 10 includes a heat quantity controller 10 A and a combustion controller 10 B. Functions of heat quantity controller 10 A and combustion controller 10 B can be achieved by software processing by controller 10 and/or hardware processing.
  • Heat quantity controller 10 A calculates a command value (Pset) for a quantity of heat generated by combustion mechanism 30 for temperature control.
  • the quantity of generated heat is generally calculated with a “scale number” being defined as a unit.
  • the quantity of heat generated by combustion mechanism 30 can be calculated in an expression (1) below in accordance with a product of a circulation flow rate Qt (L/minute) through the immediate hot water supply circulation path and amount of temperature increase ⁇ T.
  • Set temperature Tr in the immediate hot water supply operation mode may be equal to or different from a set hot water supply temperature.
  • set temperature Tr may be set to have a predetermined temperature difference from the set hot water supply temperature.
  • Circulation flow rate Qt can be detected by flow rate sensor 82 .
  • circulation flow rate Qt can be obtained also by multiplying a value of the flow rate (the flow rate in heat exchanger 40 ) detected by flow rate sensor 81 by 1/(1 ⁇ r) time by using bypass flow rate ratio r.
  • each of flow rate sensors 81 and 82 corresponds to an embodiment of the “flow rate detector” that detects a circulation flow rate.
  • thermal efficiency a ratio of a quantity of heat (thermal efficiency) used for temperature increase in heat exchanger 40 to a quantity of heat generated by combustion mechanism 30 should be taken into account.
  • thermal efficiency is assumed as 1.0.
  • Heat quantity controller 10 A sets scale number command value Pset as being restricted within a range from a smallest scale number Pmin to a largest scale number Pmax.
  • Pset calculated in accordance with the expression (1) is larger than Pmax (Pset>Pmax)
  • Pset calculated in accordance with the expression (1) is smaller than Pmin (Pset ⁇ Pmin)
  • Scale number command value Pset corresponds to the “output heat quantity command value”
  • smallest scale number Pmin corresponds to the “minimum heat quantity value”
  • largest scale number Pmax corresponds to the “maximum heat quantity value.”
  • Heat quantity controller 10 A can calculate scale number command value Pset also in common to that in the normal hot water supply operation, by substituting circulation flow rate Qt in the expression (1) with a value calculated by multiplying a flow rate detection value Q detected by flow rate sensor 81 by 1/(1 ⁇ r) time described above, substituting the term of return temperature Tb with a temperature detection value (an incoming water temperature Tw) detected by temperature sensor 73 , and substituting set temperature Tr with the set hot water supply temperature.
  • Combustion controller 10 B generates an operation command value for combustion mechanism 30 based on scale number command value Pset from heat quantity controller 10 A, a detection temperature detected by temperature sensor 71 (hot water output temperature Th), and set temperature Tr in the immediate hot water supply operation mode.
  • Combustion mechanism 30 includes a plurality of burners 31 a to 31 f , a proportional valve 34 , and solenoid valves 36 to 38 .
  • Proportional valve 34 is disposed between a source fuel supply pipe 32 and a fuel supply pipe 33 .
  • a flow rate of fuel to be supplied to fuel supply pipe 33 can be controlled based on opening of proportional valve 34 .
  • a not-shown igniter is arranged in each of the plurality of burners 31 a to 31 f . The number of burners can be set to any number.
  • Solenoid valve 36 is connected between fuel supply pipe 33 and one burner 31 a .
  • Solenoid valve 37 is connected between fuel supply pipe 33 and two burners 31 b and 31 c .
  • Solenoid valve 38 is connected between fuel supply pipe 33 and three burners 31 d to 31 f .
  • Combustion by burners 31 a to 31 f can be turned on and off by turning on and off solenoid valves 36 to 38 . Therefore, the number of burners that burn fuel (which is also referred to as a combustion burner number Nbrn below) can be controlled based on combination of on and off commands for solenoid valves 36 to 38 .
  • the operation command value for combustion mechanism 30 from combustion controller 10 B includes an on and off command for solenoid valves 36 to 38 and an opening command value for proportional valve 34 in the example in FIG. 5 .
  • Combustion controller 10 B stores in advance a table that determines combination between the combustion burner number and the flow rate of fuel in correspondence with scale number command value Pset.
  • Combustion controller 10 B can generate, by referring to the table, an on and off command for solenoid valves 36 to 38 (a combustion burner number) and an opening command value for proportional valve 34 (a flow rate of fuel) for generating a quantity of heat in accordance with scale number command value Pset.
  • combustion controller 10 B When combustion controller 10 B controls combustion mechanism 30 into the combustion stop state, it generates an off command for all of solenoid valves 36 to 38 .
  • flow rate detection value Q from flow rate sensor 81 is smaller than a minimum operating quantity MOQ, in order to deactivate combustion mechanism 30 , an off command is generated for all of solenoid valves 36 to 38 and supply of fuel is also cut off.
  • FIG. 6 shows an exemplary operation waveform diagram of temperature control in the immediate hot water supply operation mode.
  • combustion controller 10 B controls on and off of combustion by combustion mechanism 30 based on comparison of a control upper limit temperature Trh and a control lower limit temperature Trl set in accordance with set temperature Tr with hot water output temperature Th (temperature sensor 71 ).
  • combustion mechanism 30 is in a state that it outputs a quantity of heat in accordance with smallest scale number Pmin (which is also referred to as a “minimum combustion state” below) before time t 1 , hot water output temperature Th increases above set temperature Tr.
  • combustion controller 10 B controls combustion mechanism 30 to a combustion stop state. In the combustion stop state, combustion controller 10 B outputs an operation command to turn off solenoid valves 36 to 38 .
  • combustion controller 10 B controls combustion mechanism 30 to be in the combustion on state.
  • the operation command for combustion mechanism 30 is generated to output a quantity of heat in accordance with scale number command value Pset from combustion mechanism 30 .
  • hot water output temperature Th increases.
  • combustion mechanism 30 is again controlled to be in the combustion stop state at time t 6 after lapse of T 1 since time t 5 .
  • hot water output temperature Th can be controlled in a stable manner without excessively increasing.
  • intermittent combustion can be controlled in a stable manner with simplified control based on scale number command value Pset that can be calculated in common to that in the normal hot water supply operation.
  • similar control is similarly applicable also to a state in which a condition of Pset>Pmin is set. Namely, even though the condition of Pset>Pmin is set, combustion mechanism 30 can be controlled to be in the combustion stop state in response to increase in hot water output temperature Th to control upper limit temperature Trh in the combustion on state of combustion mechanism 30 , and combustion mechanism 30 can also be controlled to be in the combustion on state in accordance with scale number command value Pset in response to lowering in hot water output temperature Th to control lower limit temperature Trl in the combustion off state of combustion mechanism 30 .
  • a condition (J 2 ) for deactivating the immediate hot water supply operation mode and a condition (J 3 ) for resuming the immediate hot water supply operation mode in the stand-by mode shown in FIG. 4 will now be described. Since the immediate hot water supply circulation path is formed or cut off by crossover valve 200 in accordance with a fluid temperature in water heating system 1 A, the deactivation condition (J 2 ) and the resumption condition (J 3 ) should be set in consideration of this aspect. Though setting of the deactivation condition (J 2 ) and the resumption condition (J 3 ) which will be described below may be combined with intermittent combustion control described with reference to FIGS. 5 and 6 , it is noted for a confirmation purpose that the setting can also be realized without being combined with intermittent combustion control.
  • FIG. 7 is a flowchart illustrating control processing for determining whether or not a condition for deactivating the immediate hot water supply operation mode is satisfied. Control processing shown in FIG. 7 is repeatedly performed by controller 10 in the immediate hot water supply operation mode.
  • controller 10 determines in step (which is simply denoted as “S” below) 110 whether or not circulation flow rate Qt has lowered to a predetermined flow rate value (a first flow rate value). For example, in S 110 , when an MOQ off state in which flow rate detection value Q detected by flow rate sensor 81 is smaller than a minimum operating quantity (MOQ) continues for a certain time period (for example, two to three seconds), determination as YES is made. In this case, the minimum operating quantity (MOQ) in S 110 corresponds to the “first flow rate value.”
  • controller 10 determines whether or not a temperature detection value detected by temperature sensor 72 (return temperature Tb) has increased. For example, when a state in which return temperature Tb is higher than a criterion temperature Tth 1 continues for a certain time period (for example, approximately one to two seconds), increase in return temperature Tb is sensed and determination as YES is made in S 120 .
  • Criterion temperature Tth 1 in S 120 corresponds to the “first criterion temperature.”
  • controller 10 determines in S 130 that the deactivation condition (J 2 ) is not satisfied. Consequently, activation of circulation pump 80 is maintained and the immediate hot water supply operation mode is continued.
  • controller 10 determines in S 140 that the condition (J 2 ) for deactivating the immediate hot water supply operation mode is satisfied.
  • the deactivation condition (J 2 ) is satisfied, circulation pump 80 is deactivated and transition from the immediate hot water supply operation mode to the stand-by mode is made in FIG. 4 . In the stand-by mode, combustion mechanism 30 is also deactivated.
  • FIG. 8 is a flowchart illustrating control processing for determining whether or not the condition (J 3 ) for resuming the immediate hot water supply operation mode is satisfied. Control processing shown in FIG. 8 is repeatedly performed by controller 10 in the stand-by mode.
  • controller 10 determines in S 210 whether or not a duration of the stand-by mode has attained to a value corresponding to a predetermined time period Tx (for example, approximately ten minutes). Count of the duration of a stand-by state is started at the time of transition from the immediate hot water supply operation mode to the stand-by mode.
  • controller 10 determines in S 220 whether or not the fluid temperature in the immediate hot water supply circulation path has lowered.
  • controller 10 Until the duration of the stand-by mode attains to Tx (determination as NO in S 210 ) or when the fluid temperature in the immediate hot water supply circulation path has not lowered (determination as NO in S 220 ), controller 10 allows the process to proceed to S 270 and determines that the resumption condition (J 3 ) is not satisfied. Consequently, the stand-by mode is continued and deactivation of circulation pump 80 and combustion mechanism 30 is maintained.
  • controller 10 activates circulation pump 80 in S 230 and determines in S 240 whether or not circulation flow rate Qt increases to a predetermined flow rate value (the second flow rate value). For example, in S 240 , the controller determines whether or not it detects MOQ on which represents a flow rate detection value detected by flow rate sensor 81 (or flow rate sensor 82 ) becoming higher than the minimum operating quantity (MOQ) within a certain time period (for example, approximately one minute) from activation of circulation pump 80 (S 230 ).
  • controller 10 makes determination as NO in S 240 .
  • S 260 count by the timer that counts the duration of the stand-by mode is cleared.
  • S 270 the resumption condition (J 3 ) is determined as not being satisfied, and the stand-by mode is continued.
  • determination as NO in S 210 is maintained and circulation pump 80 is not active until Tx (minutes) elapses again.
  • Tx in S 210 corresponds to the “first time period.”
  • controller 10 When controller 10 detects MOQ on in response to activation of circulation pump 80 , controller 10 makes determination as YES in S 240 and controller 10 determines in S 250 that the condition (J 3 ) for resuming the immediate hot water supply operation mode is satisfied. When the resumption condition (J 3 ) is satisfied, transition from the stand-by mode to the immediate hot water supply operation mode is made in FIG. 4 and hence activation of circulation pump 80 from S 230 is maintained.
  • influence by the thermal bypass path within crossover valve 200 is preferably taken into consideration also in diagnosis as to an abnormal condition in the immediate hot water supply circulation path formed by activation of circulation pump 80 .
  • FIG. 9 is a flowchart illustrating control processing in diagnosis as to an abnormal condition of the immediate hot water supply circulation path performed in the immediate hot water supply operation mode.
  • controller 10 when controller 10 senses in S 310 transition from the immediate hot water supply operation off mode to the immediate hot water supply operation on mode shown in FIG. 4 (determination as YES in S 310 ), the controller determines in S 320 whether or not a predetermined time period Tc (for example, approximately five to six hours) has elapsed since stop of previous combustion by combustion mechanism 30 . Determination as YES is made in S 310 only at the time of start of the period for which the immediate hot water supply operation is to be performed as set by the timer or the like, and while the period for which the immediate hot water supply operation is to be performed continues, determination as NO is made. When controller 10 makes determination as NO in S 310 or S 320 , in S 315 , the controller makes no determination as to an abnormal condition of the immediate hot water supply circulation path. Tc corresponds to the “second time period.”
  • controller 10 Only when controller 10 makes determination as YES in both of S 310 and S 320 , controller 10 allows the process to proceed to S 330 and launches determination as to an abnormal condition of the immediate hot water supply circulation path.
  • controller 10 activates circulation pump 80 in S 332 . While circulation pump 80 is active, whether or not circulation flow rate Qt becomes higher than a diagnosis reference flow rate Qtst is determined in S 334 . In S 334 , circulation flow rate Qt based on a flow rate detection value detected by flow rate sensor 81 or 82 is compared with predetermined diagnosis reference flow rate Qtst.
  • controller 10 When controller 10 does not detect circulation flow rate Qt exceeding diagnosis reference flow rate Qtst within a certain time period (for example, approximately one minute) from activation (S 332 ) of circulation pump 80 , controller 10 makes determination as NO in S 334 and allows the process to proceed to S 335 .
  • S 335 an abnormality count value Ncnt is increased by 1, and in S 336 , increased abnormality count value Ncnt is compared with a criterion value Nth set in advance.
  • controller 10 detects an abnormal condition of the immediate hot water supply circulation path in S 338 .
  • notification apparatus 95 in FIG. 2 is used to notify a user of occurrence of the abnormal condition.
  • diagnosis as to the abnormal condition of the immediate hot water supply circulation path shown in FIG. 9 only when crossover valve 200 is reliably in the low-temperature state and the thermal bypass path is formed, diagnosis as to the abnormal condition can be launched based on a result of determination in S 310 and S 320 . Consequently, erroneous detection of the abnormal condition of the immediate hot water supply circulation path can be prevented. Unnecessary activation of circulation pump 80 with the thermal bypass path in crossover valve 200 being closed can also be avoided.
  • abnormality count value Ncnt at that time point can also be cleared to the initial value (0).
  • possibility that determination as NO in S 334 sensed previously is a temporary phenomenon caused by clogging by a foreign matter or the like is taken into consideration.
  • diagnosis as to the abnormal condition of the immediate hot water supply circulation path shown in FIG. 9 may also be combined with intermittent combustion control described with reference to FIGS. 5 and 6 and/or a mode transition condition described with reference to FIGS. 7 and 8 , it is noted for a confirmation purpose that diagnosis as to the abnormal condition can also be realized without being combined therewith.
  • FIG. 10 shows a block diagram illustrating a modification of the configuration of the water heating apparatus and the water heating system according to the modification of the present embodiment.
  • a water heating system 1 B includes a water heating apparatus 100 X, low-temperature water pipe 110 , high-temperature water pipe 120 , and crossover valve 200 .
  • Water heating apparatus 100 X includes water entry port 11 and hot water output port 12 without including circulation port 13 . Therefore, unlike water heating apparatus 100 in FIG. 1 , no circulation path 28 is provided in the inside of water heating apparatus 100 X.
  • Low-temperature water pipe 110 supplied with low-temperature water through check valve 112 has a first end connected to water entry port 11 of water heating apparatus 100 X and a second end connected to port 202 of crossover valve 200 . Connection of crossover valve 200 to low-temperature water pipe 110 , high-temperature water pipe 120 , and hot water supply faucet 330 is the same as in water heating system 1 A shown in FIG. 1 . Circulation pump 80 is connected to water entry port 11 .
  • water heating system 1 B In water heating system 1 B, during the hot water supply operation, at least some of low-temperature water introduced from low-temperature water pipe 110 into water entry port 11 is heated by the heating mechanism (combustion mechanism 30 and heat exchanger 40 ). High-temperature water obtained by heating is output from hot water supply faucet 330 through hot water output port 12 and high-temperature water pipe 120 as well as crossover valve 200 (flow path Pa) as in water heating system 1 A. Water heating apparatus 100 X can thus also perform the hot water supply operation similarly to water heating apparatus 100 .
  • a fluid path (outer path) from hot water output port 12 through high-temperature water pipe 120 , crossover valve 200 (thermal bypass path Pc), and low-temperature water pipe 110 to water entry port 11 can be formed on the outside of water heating apparatus 100 X.
  • an inner path that passes through water entry port 11 , water entry path 20 , heat exchanger 40 (heating mechanism), hot water output path 25 , and hot water output port 12 can be formed in the inside of water heating apparatus 100 X as in FIG. 1 .
  • the immediate hot water supply circulation path can be formed by the inner path and the outer path also in water heating system 1 B.
  • circulation flow rate Qt in the immediate hot water supply circulation path can be detected by flow rate sensor 81 and return temperature Tb in the immediate hot water supply circulation path can be detected by temperature sensor 73 . Therefore, also in water heating system 1 B, as in water heating system 1 A, intermittent combustion control described with reference to FIGS. 5 and 6 can be applied in the immediate hot water supply operation mode. Furthermore, also in water heating system 1 B, transition between modes including the immediate hot water supply operation mode can be controlled in accordance with FIGS. 4, 7, and 8 , and diagnosis as to an abnormal condition of the immediate hot water supply circulation path can be conducted in accordance with FIG. 9 .
  • Crossover valve 200 described in U.S. Pat. No. 6,536,464 and shown in the present embodiment is merely an exemplary “thermal water stop bypass valve” and a valve containing a thermal bypass path of which formation and closing are switched depending on a temperature could be employed instead of crossover valve 200 in the present embodiment.
  • circulation pump 80 can be arranged at any position on the outside or in the inside of water heating apparatus 100 without being limited to the configuration in the illustration in FIGS. 1 and 10 . Even in such a configuration that circulation pump 80 is not contained in water heating apparatus 100 , the immediate hot water supply operation mode described in the present embodiment can be realized by including controller 10 that controls deactivation and activation of circulation pump 80 .
  • water heating apparatuses 100 and 100 X each include a bypass configuration (bypass path 29 and flow rate regulation valve 90 ) is described in the present embodiment
  • the immediate hot water supply operation mode described in the present embodiment can be realized also in the configuration of water heating apparatuses 100 and 100 X from which the bypass configuration is excluded.

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CN115095985A (zh) * 2022-06-30 2022-09-23 九阳股份有限公司 一种即热出水机循环预热方法和控制方法
EP4198406A1 (en) * 2021-12-13 2023-06-21 Kyungdong Navien Co., Ltd. Fluid heating apparatus

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JP2021103011A (ja) * 2019-12-24 2021-07-15 株式会社ノーリツ 給湯装置

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JPH0762530B2 (ja) * 1991-08-30 1995-07-05 株式会社ノーリツ 給湯装置
JP3311413B2 (ja) * 1993-02-26 2002-08-05 東陶機器株式会社 循環式給湯装置
JP4253006B2 (ja) * 2006-03-27 2009-04-08 リンナイ株式会社 循環型給湯装置
JP4234738B2 (ja) * 2006-07-26 2009-03-04 リンナイ株式会社 連結給湯システム
US10215424B2 (en) * 2013-11-27 2019-02-26 Advanced Conservation Technology Distribution, Inc Methods and apparatus for remotely monitoring and/or controlling a plumbing system
JP6092815B2 (ja) * 2014-06-06 2017-03-08 リンナイ株式会社 給湯装置
US10302312B2 (en) * 2014-12-22 2019-05-28 Battelle Memorial Institute Estimation of unknown states for an electric water heater with thermal stratification and use of same in demand response and condition-based maintenance
JP2016125692A (ja) * 2014-12-26 2016-07-11 リンナイ株式会社 給湯システム
JP6819210B2 (ja) * 2016-10-25 2021-01-27 株式会社ノーリツ 給湯装置

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EP4198406A1 (en) * 2021-12-13 2023-06-21 Kyungdong Navien Co., Ltd. Fluid heating apparatus
CN115095985A (zh) * 2022-06-30 2022-09-23 九阳股份有限公司 一种即热出水机循环预热方法和控制方法

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