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WO2009015435A1 - Dispositif de chauffage de fluide - Google Patents

Dispositif de chauffage de fluide Download PDF

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Publication number
WO2009015435A1
WO2009015435A1 PCT/AU2008/001109 AU2008001109W WO2009015435A1 WO 2009015435 A1 WO2009015435 A1 WO 2009015435A1 AU 2008001109 W AU2008001109 W AU 2008001109W WO 2009015435 A1 WO2009015435 A1 WO 2009015435A1
Authority
WO
WIPO (PCT)
Prior art keywords
fluid
heat exchanger
heating
mains
heater according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU2008/001109
Other languages
English (en)
Inventor
Albert Massey Trihey
John Massey Trihey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hydox Pty Ltd
Original Assignee
Hydox Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2007203612A external-priority patent/AU2007203612A1/en
Priority claimed from AU2008901467A external-priority patent/AU2008901467A0/en
Application filed by Hydox Pty Ltd filed Critical Hydox Pty Ltd
Priority to CN2008801061838A priority Critical patent/CN101878399A/zh
Priority to EP08772731A priority patent/EP2288856A1/fr
Priority to AU2008281327A priority patent/AU2008281327A1/en
Priority to US12/671,420 priority patent/US20100282440A1/en
Publication of WO2009015435A1 publication Critical patent/WO2009015435A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H8/00—Fluid heaters characterised by means for extracting latent heat from flue gases by means of condensation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D3/00—Hot-water central heating systems
    • F24D3/08—Hot-water central heating systems in combination with systems for domestic hot-water supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/10—Continuous-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
    • F24H1/12—Continuous-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 in which the water is kept separate from the heating medium
    • F24H1/121—Continuous-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 in which the water is kept separate from the heating medium using electric energy supply
    • F24H1/122—Continuous-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 in which the water is kept separate from the heating medium using electric energy supply combined with storage tank
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/48—Water heaters for central heating incorporating heaters for domestic water
    • F24H1/52—Water heaters for central heating incorporating heaters for domestic water incorporating heat exchangers for domestic water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/48—Water heaters for central heating incorporating heaters for domestic water
    • F24H1/52—Water heaters for central heating incorporating heaters for domestic water incorporating heat exchangers for domestic water
    • F24H1/526—Pipes in pipe heat exchangers for sanitary water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H7/00—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release
    • F24H7/02—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid
    • F24H7/04—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid
    • F24H7/045—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid using fluid fuel
    • F24H7/0466—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid using fluid fuel the transfer fluid being water
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]

Definitions

  • the present invention relates to a fluid heater and in particular to a water or oil heater.
  • the invention has been developed particularly for use as an instantaneous water heater and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular use and may also be used to heat other fluids, such as oil.
  • gas and oil fuelled storage water heaters can only store a set volume of water they are limited in their ability to always supply hot water on demand. If the stored water runs out, the user has to wait until the heater re-heats the cold water to the temperature required by the user. The delay in re-heating the stored water is prolonged by the gas or oil input in the combustion chamber which is generally very low to ensure a high combustion efficiency (thermal efficiency) performance.
  • Any combustion products which are driven or flow through a flue / heat exchanger mechanism which is part of a storage tank cannot drop the flue products temperature below the stored water temperature. The flue products must exit the unit at a higher temperature than the stored water in the tank.
  • Instantaneous water heaters were first developed as an alternative to conventional storage water heaters. Instantaneous and continuous flow water heaters maintain a relatively high combustion / thermal efficiency. However, they also suffer several deficiencies in performance which result in energy and water wastage.
  • Instantaneous water heaters become cold in standby mode and have no hot water storage capacity. This feature ensures that there are no maintenance losses from the unit during its "off period (i.e. after the heater has cooled down, after a heating period, and lost its residual heat to the atmosphere). Conversely storage tanks have a large tank surface area, which continually loses energy in standby mode despite the insulation around the tank.
  • the instantaneous unit's burner is activated by a water flow sensor which activates the gas or oil burner when the unit senses water flowing though the heater. Because the unit is cold when the water starts flowing through it, there is a significant delay whilst the burner heats up the cold water heat exchanger which has cold (mains) water flowing through it. Consequently the first several litres of water which leave the unit are cold and the water (which is still flowing) slowly heats to the user's desired temperature. Whilst the user is waiting for the flowing water to heat up, the water output from the heater is wasted. This is not only a waste of water, but also of the gas or oil energy used in the heating up process.
  • the water heat exchanger inside the combustion chamber and the combustion chamber case / fixtures remains very hot. Because the mains water is no longer flowing through the unit the (instantaneous) heater has no method of capturing or storing the remaining heat which quickly dissipates into the atmosphere and is lost / wasted.
  • Instantaneous water heaters can waste up to 25 litres per day (or more) on a typical domestic user pattern because of the delay the unit suffers on start up as described above. The more times the unit is started from a cold start equates to more water and energy losses from the same cause.
  • Conventional instantaneous water heaters have a combustion / thermal efficiency of approximately 80% when the unit has stabilised the hot water delivery temperature.
  • Instantaneous units may have a higher combustion / thermal efficiency for a short period just after the burner activates due to the water heat exchanger being cold however this higher efficiency performance is negated by the fact that the water flowing though the unit (during the short high efficiency period) is not hot enough to use by the user and is consequently wasted.
  • Some instantaneous units are fitted with a secondary (mains water) pre-heating heat exchanger, which can raise the efficiency to the around 90%.
  • a secondary (mains water) pre-heating heat exchanger which can raise the efficiency to the around 90%.
  • the use of a preheating heat exchanger has no significant effect on the water or energy wastage or the associated delays in supplying hot water previously described.
  • mains pressure storage water heaters can also fail when they are supplied with water which is corrupted with impurities, such as mud, silt or salt, which can collect at the bottom of the tank and sit / collect on the bottom tank dome, which is used as a heat exchange surface area by the gas combustion chamber.
  • impurities such as mud, silt or salt
  • the build up of sediment causes the heat exchange performance to be detrimentally effected and the efficiency of the unit continually drops as the build up of sediment increases.
  • the build up of sediment will prevent the mains water in the tank from scrubbing the bottom heat exchange dome, which prevents the dome (combustion chamber surface) from being cooled by the mains water. Over time the bottom tank dome will overheat, distort, and ultimately rupture the tank.
  • the present invention provides a fluid heater comprising: a storage reservoir for storing heating fluid; a burner for heating the heating fluid; a first heat exchanger located outside said storage reservoir; a first fluid circuit connecting the storage reservoir with the first heat exchanger for carrying heating fluid from the storage reservoir, through the first heat exchanger and back to the storage reservoir; and a second fluid circuit connecting a first inlet for mains fluid to a first outlet for heated mains fluid via the first heat exchanger, wherein the first heat exchanger is adapted to exchange heat between said heating fluid and said mains fluid.
  • the first heat exchanger preferably includes a first pipe-in-pipe heat exchanger.
  • the first pipe-in-pipe heat exchanger preferably includes a first thermally conductive pipe for containing the heating fluid, said first thermally conductive pipe being located within a second thermally conductive pipe for containing the mains fluid.
  • the first thermally conductive pipe is adapted to carry the mains fluid and the second thermally conductive pipe is adapted to carry the heating fluid.
  • the first heat exchanger preferably includes a plurality of the first and second thermally conductive pipes, with each said first thermally conductive pipe being located within a respective said second thermally conductive pipe.
  • the first thermally conductive pipes are preferably connected in parallel and the second thermally conductive pipes preferably loop backward and forward through the first heat exchanger.
  • the second thermally conductive pipes preferably include a first group of pipes connected in parallel to a second group of pipes.
  • the first heat exchanger is preferably adapted to be heated by combustion products generated by the burner.
  • the burner is preferably a gas burner and the first heat exchanger is preferably located above the gas burner, such that combustion products from the gas burner rise toward the first heat exchanger.
  • the first heat exchanger preferably includes an array of fins for absorbing heat from the combustion products and transferring said heat to the mains fluid and/or heating fluid in said first heat exchanger.
  • a second heat exchanger, for exchanging heat between the heating fluid and the mains fluid, is preferably provided downstream of the first heat exchanger.
  • the second heat exchanger is preferably located below the first heat exchanger, such that combustion products passing the second heat exchanger rise toward the first heat exchanger to heat the first heat exchanger.
  • the second heat exchanger preferably includes a second pipe-in- pipe heat exchanger.
  • the second pipe-in-pipe heat exchanger preferably includes a third thermally conductive pipe for containing the mains fluid, said third thermally conductive pipe being located within a fourth thermally conductive pipe for containing the heating fluid.
  • the third thermally conductive pipe is adapted to carry the heating fluid
  • the fourth thermally conductive pipe is adapted to carry the mains fluid.
  • the second heat exchanger preferably includes an array of fins for absorbing heat from the burner and transferring said heat to the mains fluid and/or heating fluid in said second heat exchanger.
  • the second heat exchanger preferably includes a plurality of the third and fourth thermally conductive pipes, with each said third thermally conductive pipe being located within a respective said fourth thermally conductive pipe.
  • the third thermally conductive pipes are preferably connected in parallel and the fourth thermally conductive pipes preferably loop backward and forward through the second heat exchanger.
  • the fourth thermally conductive pipes are preferably connected in series.
  • the second fluid circuit preferably includes a portion that bypasses the second heat exchanger.
  • a third heat exchanger, for exchanging heat between the heating fluid and the mains fluid, is preferably provided downstream of the first heat exchanger, and more preferably also downstream of the second heat exchanger.
  • the third heat exchanger is preferably a pipe-in-pipe heat exchanger.
  • the third heat exchanger includes a fifth thermally conductive pipe for containing the mains fluid, said fifth thermally conductive pipe being located within a sixth thermally conductive pipe for containing the heating fluid.
  • the fifth thermally conductive pipe is adapted to carry the heating fluid and the sixth thermally conductive pipe is adapted to carry the mains fluid.
  • the first fluid circuit is preferably defined in part by a first fluid conduit extending from the storage reservoir through the first heat exchanger, through the second heat exchanger, and back to the storage reservoir.
  • the first fluid circuit is preferably defined in part by a third fluid conduit extending from the storage reservoir through the third heat exchanger, through the second heat exchanger and back to the storage reservoir.
  • the third fluid conduit preferably intersects the first fluid conduit upstream of the second heat exchanger.
  • a first valve is preferably provided in the first fluid conduit for selectively preventing flow of the heating fluid through the first heat exchanger.
  • the first valve is preferably located between the first heat exchanger and the intersection with the third fluid conduit.
  • the first valve is preferably a solenoid valve.
  • a second valve is preferably provided in the first fluid conduit for selectively preventing flow of the heating fluid from the storage reservoir via the first fluid conduit.
  • the second valve is preferably located between the storage reservoir and the first heat exchanger.
  • the second valve is preferably a solenoid valve.
  • An expansion valve is preferably provided between the second fluid circuit and the first fluid circuit to allow mains fluid to pass from the second fluid circuit into the first fluid circuit when pressure within the second fluid circuit increases to a predetermined level.
  • a first pump is preferably provided for pumping heating fluid through the first fluid circuit.
  • a second outlet is preferably provided in the first fluid circuit to allow for supply of the heating fluid to a fourth heat exchanger for exchanging heat between the heating fluid and fluid in an external hydronic heating circuit.
  • the second outlet is preferably provided in a fourth fluid conduit that branches off from the first conduit downstream of the second heat exchanger.
  • a second inlet is preferably provided in the first fluid circuit to allow for the return of heating fluid from the fourth heat exchanger.
  • the second inlet preferably feeds into a fifth fluid conduit that feeds into the first heat exchanger.
  • a third valve is preferably provided for selectively disconnecting flow of heating fluid through the fifth fluid conduit.
  • the third valve is preferably a solenoid valve.
  • a second pump is preferably provided in the fourth or fifth conduits for pumping heating fluid through the fourth and fifth fluid conduits and the fourth heat exchanger.
  • the fourth heat exchanger is preferably a plate heat exchanger.
  • a valve is preferably provided for selectively controlling the supply of fuel to the burner.
  • a plurality of temperature and flow sensors are preferably provided for sensing the temperature and flow of fluids at various locations within the fluid heater.
  • a controller is preferably responsive to the sensors for controlling flow of fluid through the fluid heater for safety and/or to allow the fluid heater to operate in various modes.
  • a first temperature sensor is for sensing the temperature of the heating fluid adjacent its point of return to the storage reservoir.
  • a second temperature sensor is provided for sensing the temperature of the heating fluid adjacent its point of return to the storage reservoir.
  • a third temperature sensor is provided for sensing the temperature of the heating fluid downstream of the second heat exchanger.
  • a first flow sensor is provided for sensing the flow of mains fluid adjacent the first inlet.
  • the first flow sensor is preferably a thermal sensor, which senses flow based on the relative temperatures of the mains fluid and the heating fluid.
  • the first flow sensor is preferably located between the mains fluid circuit and the heating circuit adjacent the first inlet.
  • the controller is preferably also responsive to controls of the hydronic heating circuit.
  • the controller is preferably adapted to close the first valve in response to the first flow sensor sensing flow of mains fluid, to thereby prevent heating fluid from flowing through the first heat exchanger.
  • the controller is preferably adapted to actuate a heating sequence of the burner in response to the first flow sensor sensing flow of mains fluid and the first temperature sensor indicating a temperature below a first predetermined value, preferably of approximately 82°C.
  • the controller is preferably adapted to deactivate the burner in response to the first flow sensor sensing flow of mains fluid and the first temperature sensor indicating a temperature above a second predetermined value, preferably of around 85°C.
  • the controller is preferably adapted to open the first valve in response to the first flow sensor sensing a stoppage of mains fluid flow, to thereby allow heating fluid to flow through the first heat exchanger to scavenge residual heat in the first heat exchanger.
  • the controller is preferably adapted to actuate the burner in response to the first flow sensor sensing a stoppage of mains fluid flow and the second temperature sensor indicating a temperature below a third predetermined value, preferably of around 65 0 C.
  • the controller is preferably adapted to deactivate the burner in response to the first flow sensor sensing a stoppage of mains fluid flow and the second temperature sensor indicating a temperature above a fourth predetermined value, preferably of around 80°C.
  • the controller is preferably adapted to actuate the first pump and the second pump in response to the hydronic heating system being activated.
  • the controller is preferably adapted to open the third valve in response to the hydronic heating system being activated.
  • the controller is preferably adapted to close the second valve in response to the hydronic heating system being activated.
  • the controller is preferably adapted to close the third valve and deactivate the second pump if the mains water temperature at the first outlet falls below a predetermined value.
  • An inlet to the first fluid circuit from the storage reservoir is preferably spaced apart from an outlet from the first fluid circuit into the storage reservoir. More preferably, the inlet and outlet are located at diametrically opposite sides of the storage reservoir.
  • the fluid heater preferably includes an insulated housing.
  • the present invention provides a fluid heater comprising: a storage reservoir for storing heating fluid; a burner for heating the heating fluid; a first heat exchanger; a first fluid circuit connecting the storage reservoir with the first heat exchanger for carrying heating fluid from the storage reservoir, through the first heat exchanger and back to the storage reservoir; and a second fluid circuit connecting an inlet for mains fluid to an outlet for heated mains fluid via the first heat exchanger, the second fluid circuit including a portion that passes through an exhaust path of burner heat expelled after heating of the heating fluid, wherein the first heat exchanger is adapted to exchange heat between said heating fluid and said mains fluid.
  • the first heat exchanger is preferably located outside the storage reservoir.
  • the first heat exchanger preferably includes a first pipe-in-pipe heat exchanger.
  • the first pipe-in-pipe heat exchanger preferably includes a first thermally conductive pipe for containing the heating fluid, said first thermally conductive pipe being located within a second thermally conductive pipe for containing the mains fluid.
  • the first thermally conductive pipe is adapted to carry the mains fluid and the second thermally conductive pipe is adapted to carry the heating fluid.
  • the first heat exchanger preferably includes a plurality of the first and second thermally conductive pipes, with each said first thermally s conductive pipe being located within a respective said second thermally conductive pipe.
  • the first thermally conductive pipes are preferably connected in parallel and the second thermally conductive pipes preferably loop backward and forward through the first heat exchanger.
  • the second thermally conductive pipes preferably include a first group of pipes connected in parallel to a second group of pipes.
  • the first heat exchanger is preferably adapted to be heated by combustion products generated by the burner.
  • the burner is preferably a gas burner and the first heat exchanger is preferably located above the gas burner, such that combustion products from the gas burner rise toward the first heat exchanger.
  • the first heat exchanger preferably includes an array of fins for absorbing heat from the combustion products and transferring saids heat to the mains fluid and/or heating fluid in said first heat exchanger.
  • a second heat exchanger for exchanging heat between the heating fluid and the mains fluid, is preferably provided downstream of the first heat exchanger.
  • the second heat exchanger is preferably located below the first heat exchanger, such that combustion products passing the second heat exchanger rise toward the first heat exchanger to heat0 the first heat exchanger.
  • the second heat exchanger preferably includes a second pipe-in- pipe heat exchanger.
  • the second pipe-in-pipe heat exchanger preferably includes a third thermally conductive pipe for containing the mains fluid, said third thermally conductive pipe being located within a fourth thermally conductive pipe for containing the heating fluid.
  • the third thermally conductive pipe is adapted to carry the heatings fluid and the fourth thermally conductive pipe is adapted to carry the mains fluid.
  • the second heat exchanger preferably includes an array of fins for absorbing heat from the burner and transferring said heat to the mains fluid and/or heating fluid in said second heat exchanger.
  • the second heat exchanger preferably includes a plurality of the third and fourth thermally conductive pipes, with each said third thermally conductive pipe being0 located within a respective said fourth thermally conductive pipe.
  • the third thermally conductive pipes are preferably connected in parallel and the fourth thermally conductive pipes preferably loop backward and forward through the second heat exchanger.
  • the fourth thermally conductive pipes are preferably connected in series.
  • the second fluid circuit preferably includes a portion that bypasses the second heat exchanger.
  • a third heat exchanger for exchanging heat between the heating fluid and the mains fluid, is preferably provided downstream of the first heat exchanger, and more preferably also downstream of the second heat exchanger.
  • the third heat exchanger is preferably a pipe-in-pipe heat exchanger. More preferably, the third heat exchanger includes a fifth thermally conductive pipe for containing the mains fluid, said fifth thermally conductive pipe being located within a sixth thermally conductive pipe for containing the heating fluid.
  • the fifth thermally conductive pipe is adapted to carry the heating fluid and the sixth thermally conductive pipe is adapted to carry the mains fluid.
  • the first fluid circuit is preferably defined in part by a first fluid conduit extending from the storage reservoir through the first heat exchanger, through the second heat exchanger, and back to the storage reservoir.
  • the first fluid circuit is preferably defined in part by a third fluid conduit extending from the storage reservoir through the third heat exchanger, through the second heat exchanger and back to the storage reservoir.
  • the third fluid conduit preferably intersects the first fluid conduit upstream of the second heat exchanger.
  • a first valve is preferably provided in the first fluid conduit for selectively preventing flow of the heating fluid through the first heat exchanger.
  • the first valve is preferably located between the first heat exchanger and the intersection with the third fluid conduit.
  • the first valve is preferably a solenoid valve.
  • a second valve is preferably provided in the first fluid conduit for selectively preventing flow of the heating fluid from the storage reservoir via the first fluid conduit.
  • the second valve is preferably located between the storage reservoir and the first heat exchanger.
  • the second valve is preferably a solenoid valve.
  • An expansion valve is preferably provided between the second fluid circuit and the first fluid circuit to allow mains fluid to pass from the second fluid circuit into the first fluid circuit when pressure within the second fluid circuit increases to a predetermined level.
  • a first pump is preferably provided for pumping heating fluid through the first fluid circuit.
  • a second outlet is preferably provided in the first fluid circuit to allow for supply of the heating fluid to a fourth heat exchanger for exchanging heat between the heating fluid and fluid in an external hydronic heating circuit.
  • the second outlet is preferably provided in a fourth fluid conduit that branches off from the first conduit downstream of the second heat exchanger.
  • a second inlet is preferably provided in the first fluid circuit to allow for the return of heating fluid from the fourth heat exchanger.
  • the second inlet preferably feeds into a fifth fluid conduit that feeds into the first heat exchanger.
  • a third valve is preferably provided for selectively disconnecting flow of heating fluid through the fifth fluid conduit.
  • the third valve is preferably a solenoid valve.
  • a second pump is preferably provided in the fourth or fifth conduits for pumping heating fluid through the fourth and fifth fluid conduits and the fourth heat exchanger.
  • the fourth heat exchanger is preferably a plate heat exchanger.
  • a valve is preferably provided for selectively controlling the supply of fuel to the burner.
  • a plurality of temperature and flow sensors are preferably provided for sensing the temperature and flow of fluids at various locations within the fluid heater.
  • a controller is preferably responsive to the sensors for controlling flow of fluid through the fluid heater for safety and/or to allow the fluid heater to operate in various modes.
  • a first temperature sensor is for sensing the temperature of the heating fluid adjacent its point of return to the storage reservoir.
  • a second temperature sensor is provided for sensing the temperature of the heating fluid adjacent its point of return to the storage reservoir.
  • a third temperature sensor is provided for sensing the temperature of the heating fluid downstream of the second heat exchanger.
  • a first flow sensor is provided for sensing the flow of mains fluid adjacent the first inlet.
  • the first flow sensor is preferably a thermal sensor, which senses flow based on the relative temperatures of the mains fluid and the heating fluid.
  • the first flow sensor is preferably located between the mains fluid circuit and the heating circuit adjacent the first inlet.
  • the controller is preferably also responsive to controls of the hydronic heating circuit.
  • the controller is preferably adapted to close the first valve in response to the first flow sensor sensing flow of mains fluid, to thereby prevent heating fluid from flowing through the first heat exchanger.
  • the controller is preferably adapted to actuate the burner in response to the first flow sensor sensing flow of mains fluid and the first temperature sensor indicating a temperature below a first predetermined value, preferably of approximately 82°C.
  • the controller is preferably adapted to deactivate the burner in response to the first flow sensor sensing flow of mains fluid and the first temperature sensor indicating a temperature above a second predetermined value, preferably of around 85°C.
  • the controller is preferably adapted to open the first valve in response to the first flow sensor sensing a stoppage of mains fluid flow, to thereby allow heating fluid to flow through the first heat exchanger to scavenge residual heat in the first heat exchanger.
  • the controller is preferably adapted to actuate the burner in response to the first flow sensor sensing a stoppage of mains fluid flow and the second temperature sensor indicating a temperature below a third predetermined value, preferably of around 65°C.
  • the controller is preferably adapted to deactivate the burner in response to the first flow sensor sensing a stoppage of mains fluid flow and the second temperature sensor indicating a temperature above a fourth predetermined value, preferably of around 80°C.
  • the controller is preferably adapted to actuate the first pump and the second pump in response to the hydronic heating system being activated.
  • the controller is preferably adapted to open the third valve in response to the hydronic heating system being activated.
  • the controller is preferably adapted to close the second valve in response to the hydronic heating system being activated.
  • the controller is preferably adapted to close the third valve and deactivate the second pump if the mains water temperature at the first outlet falls below a predetermined value.
  • An inlet to the first fluid circuit from the storage reservoir is preferably spaced apart from an outlet from the first fluid circuit into the storage reservoir. More preferably, the inlet and outlet are located at diametrically opposite sides of the storage reservoir.
  • the fluid heater preferably includes an insulated housing.
  • the present invention provides a method for heating fluid, said method comprising the steps of: providing a supply of heating fluid; heating the heating fluid; providing mains fluid; heating the mains fluid by exchanging heat between said heating fluid and said mains fluid; and further heating the mains fluid using residual heat from the step of heating the heating fluid.
  • the method preferably includes the further step of reheating the heating fluid if the temperature of the heating fluid falls below a predetermined lower limit.
  • the method preferably includes the further step of stopping the heating step if the temperature of the heating fluid reaches a predetermined upper limit.
  • the method preferably includes the step of changing the upper and lower limits based on whether mains fluid is flowing.
  • the method preferably includes the additional step of heating fluid in an external hydronic heating circuit by exchanging heat between the heating fluid in the first fluid circuit and fluid in the hydronic heating circuit.
  • the exchanging of heat between the heating fluid in the first fluid circuit and fluid in the hydronic heating circuit is preferably 5 stopped if a temperature of the heating fluid in the first fluid circuit falls below a predetermined lower limit.
  • FIGURE 1 is a schematic view of a first preferred embodiment of a water heater, showing relative water flow paths in a mains (domestic) water heating mode;
  • FIGURE 2 is a schematic view of the heater, showing the relative water flow paths in a maintenance heating mode
  • FIGURE 3 is a schematic view of the heater, showing the relative water flow paths in a i s hydronic heating mode
  • FIGURE 4 is a schematic view of the heater with its front cover removed
  • FIGURE 5 is a schematic cross-sectional view, taken along line A-A in FIGURE 4, showing the flow paths of air and combustion products in a mains (domestic) water heating mode;
  • FIGURE 6 is a schematic cross-sectional view, taken along line B-B in FIGURE 4;
  • FIGURE 7 is a schematic perspective rear view of the water heater chassis, showing air channels mounted on the back of the chassis and the top and bottom storage reservoir clamps;
  • FIGURE 8 is a schematic perspective rear view of the heating fluid storage reservoir
  • FIGURE 9 is a schematic perspective rear view of the chassis with the storage reservoir fitted in position, showing the air channels mounted on the back of the chassis and the top and bottom storage reservoir clamps;
  • FIGURE 10 is a schematic perspective front view of the combustion chamber (second) heat exchanger, with fan mounted on the bottom and flue connecting duct mounted on the0 top, and also showing the upper (first) heat exchanger;
  • FIGURE 11 is a schematic perspective front view of the combustion chamber (second) heat exchanger, with fan mounted on the bottom and flue connecting duct mounted on the top, connected to the upper (first) heat exchanger and third pipe-in-pipe heat exchanger, which forms a sub-assembly;
  • FIGURE 12 is a schematic perspective front view of the chassis and storage reservoir;
  • FIGURE 13 is a schematic perspective front view of the complete chassis sub-assembly, incorporating the three heat exchangers, the circulation pump and gas valve mounted in position on the chassis, and with the storage reservoir mounted on the back of the chassis (not shown);
  • FIGURE 14 is a schematic exploded cross-sectional view, taken along line C-C of FIGURE 5, showing the fitting of the complete chassis sub-assembly to the insulated housing;
  • FIGURE 15 is a schematic cross-sectional view, taken along line C-C of FIGURE 5, showing the complete chassis sub-assembly in position inside the insulated housing, but without the top securing insulation and front cover fitted;
  • FIGURE 16 is a schematic exploded cross-sectional view, taken along line C-C of FIGURE 5, showing the fitting of the top securing insulation sections and the front cover;
  • FIGURE 17 is a schematic cross-sectional view, taken along line C-C of FIGURE 5;
  • FIGURE 18 is a schematic view of the water heater showing the filling / priming flow path of mains water entering the de-oxygenated heating water circuit;
  • FIGURE 19 is a circuit drawing of the water heater's electronic control system
  • FIGURE 20 is a schematic view of a second embodiment of a water heater
  • FIGURE 21 is a schematic cross-sectional view, taken along line A-A in FIGURE 20, showing the flow paths of air and combustion products in mains (domestic) water, hydronic, and maintenance heating modes, when the burner is activated;
  • FIGURE 22 is a schematic view of the water heater of FIGURE 20, showing mains water flow paths in a mains (domestic) water heating mode;
  • FIGURE 23 is a schematic view of the heater of FIGURE 20, showing the deoxygenated water flow paths in a maintenance heating mode, with the second (mains) fluid circuit omitted for ease of understanding;
  • FIGURE 24 is a schematic view of the heater of FIGURE 20, showing the deoxygenated water flow paths in a hydronic heating mode, with the second (mains) fluid circuit omitted for ease of understanding;
  • FIGURES 25-27 schematically illustrate the filling/priming flow paths through the heater of FIGURE 20;
  • FIGURE 28 is a front elevational view of the third heat exchanger of the heater of FIGURE 20;
  • FIGURE 29 is a side elevational view of the third heat exchanger;
  • FIGURE 30 is a top plan view of the third heat exchanger;
  • FIGURE 31 is a cross-sectional view of the third heat exchanger, taken along line 31-31 of FIGURE 28;
  • FIGURE 32 is a cross-sectional view of the third heat exchanger, taken along line 32-32 of FIGURE 30;
  • FIGURE 33 is a cross-sectional view of the third heat exchanger, taken along line 32-32 of FIGURE 30, showing a flow path of mains water therethrough;
  • FIGURE 34 is an enlargement of FIGURE 31;
  • FIGURE 35 is a wiring diagram of the heater of FIGURE 20 when in a mains (domestic) water heating mode and with the burner on and mains water flowing through the unit;
  • FIGURE 36 is a wiring diagram of the heater of FIGURE 20 when in a maintenance mode, with the burner off and the de-oxygenated water in the storage reservoir hot;
  • FIGURE 37 is a wiring diagram of the heater of FIGURE 20 when in a maintenance mode, with the burner on and reheating the storage reservoir with no mains water flowing through the unit;
  • FIGURE 38 is a schematic drawing of an overflow outlet of the heater of FIGURE 20.
  • a water heater 100 comprising a storage reservoir 1 for storing de-oxygenated water for use as a heating fluid.
  • the pressure within the storage reservoir is atmospheric.
  • the storage reservoir includes an overflow 37.
  • the heater also includes a combustion chamber 8 housing a gas burner 5 for heating the de-oxygenated water.
  • a first heat exchanger 11, for exchanging heat between the de-oxygenated water and mains water, is located outside of the storage reservoir 1.
  • a first fluid circuit 200 connects the storage reservoir 1 with the first heat exchanger 11 for carrying de-oxygenated water from the storage reservoir 1, through the first heat exchanger 11 and back to the storage reservoir 1.
  • the inlets 201, 202 to the first fluid circuit 200 from the storage reservoir 1 are spaced apart from the outlet 203 from the first fluid circuit 200 into the storage reservoir 1.
  • the de-oxygenated water within the first fluid circuit 200 is recycled during operation of the water heater 100.
  • a second fluid circuit 300 connects a first inlet 19 for mains water to a first outlet 27 for heated mains water via the first heat exchanger 11. The mains water and de- oxygenated water are not mixed during operation of the water heater 100.
  • the first heat exchanger 11 includes a pipe-in-pipe heat exchanger 12 having a plurality of first thermally conductive pipes 12a for containing the de-oxygenated water.
  • the first thermally conductive pipes 12a are each located within a respective second thermally conductive pipe 12b for containing the mains water.
  • the first thermally conductive pipes 12a are connected in parallel and the second thermally conductive pipes 12b loop backward and forward through the first heat exchanger 11.
  • the second thermally conductive pipes 12b include a first (upper) group of pipes connected in parallel to a second (lower) group of pipes.
  • the first heat exchanger 11 is located above the gas burner 5, such that combustion products from the gas burner 5 rise toward the first heat exchanger to heat the first heat exchanger 11.
  • the combustion products enter the first heat exchanger 11 at a temperature in the range of approximately 100°C to 16O 0 C, dependent on the water heater's temperature settings and burner fuel input rate.
  • the first heat exchanger 11 also includes an array of fins 12c for absorbing heat from the burner combustion products and transferring the absorbed heat to the mains water and/or de- oxygenated water in the first heat exchanger 11.
  • a second heat exchanger 101 for exchanging heat between the de-oxygenated water and the mains water, is provided downstream of the first heat exchanger 11.
  • the second heat exchanger 101 is located below the first heat exchanger 11, such that combustion products passing the second heat exchanger 101 rise toward the first heat exchanger 11 to heat the first heat exchanger 11.
  • the second heat exchanger 101 also includes a pipe-in- pipe heat exchanger 10 having a plurality of third thermally conductive pipes 10a for containing the mains water.
  • the third thermally conductive pipes 10a are each contained within a respective fourth thermally conductive pipe 10b for containing the de- oxygenated water.
  • the second heat exchanger 101 also includes an array of fins 10c for absorbing heat from the burner combustion products and transferring the heat to the mains water and/or de-oxygenated water in the second heat exchanger 101.
  • the third thermally conductive pipes 10a are connected in parallel and the fourth thermally conductive pipes 10b loop backward and forward through the second heat exchanger 101.
  • the fourth thermally conductive pipes 10b are connected in series.
  • the second fluid circuit 300 includes a portion 301 that bypasses the second heat exchanger 101.
  • the bypassing portion 301 re-joins the remainder of the second fluid circuit 300 upstream of a third heat exchanger 25, at a position 26.
  • the third heat exchanger 25 is located downstream of the second heat exchanger 101 and is adapted to exchange heat between the de-oxygenated water and the mains water.
  • the third heat exchanger 25 also includes a pipe-in-pipe heat exchanger having a fifth thermally conductive pipe 25a for containing the mains water.
  • the fifth thermally conductive pipe 25a is located within a sixth thermally conductive pipe 25b for containing hot de-oxygenated water drawn directly from the storage reservoir 1.
  • the first fluid circuit 200 is defined in part by a first fluid conduit 204 extending from the storage reservoir 1 through the first heat exchanger 11 , through the second heat exchanger 101, and back to the storage reservoir 1.
  • the first fluid circuit 200 is defined in part by a third fluid conduit 205 extending from the storage reservoir 1 through the third heat exchanger 25, through the second heat exchanger 101 and back to the storage reservoir 1.
  • the third fluid conduit 205 intersects the first fluid conduit 204 upstream of the second heat exchanger 101.
  • a first solenoid valve 14 is provided in the first fluid conduit 204, between the first heat exchanger 11 and the intersection with the third fluid conduit 205, for selectively preventing flow of the de-oxygenated water through the first heat exchanger 11.
  • a second valve 35 is provided in the first fluid conduit 204, between the storage reservoir 1 and the first heat exchanger 11, for selectively preventing flow of the de-oxygenated water from the storage reservoir 1 via the first fluid conduit 204.
  • An expansion valve 36 is provided between the second fluid circuit 300 and the first fluid circuit 200 to allow mains fluid to pass from the second fluid circuit 300 into the first fluid circuit 200 when pressure within the second fluid circuit 300 increases to a predetermined level.
  • a first pump 28 is provided for pumping de-oxygenated water through the first fluid circuit 200.
  • a drain tap 47 is also provided in the first fluid circuit to allow drainage of the de-oxygenated water for servicing.
  • a second outlet 30 is provided in the first fluid circuit 200 to allow for supply of the de- oxygenated water to a fourth plate-type heat exchanger 32 for exchanging heat between the de-oxygenated water and fluid in an external hydronic heating circuit (not shown).
  • the second outlet 30 feeds into in a fourth fluid conduit 206 that branches off from the first conduit 204 downstream of the second heat exchanger 101.
  • a second inlet 30a is provided in the first fluid circuit 200 to allow for the return of de-oxygenated water from the fourth heat exchanger 32.
  • the second inlet 30a feeds into a fifth fluid conduit 207 that feeds into the first heat exchanger 11.
  • a third solenoid valve 31 is provided for selectively disconnecting flow of de-oxygenated water through the fifth fluid conduit 207.
  • a second pump 29 is provided in the fifth conduit 207 for pumping de-oxygenated water through the fourth 206 and fifth 207 fluid conduits and the fourth heat exchanger 32.
  • a plurality of temperature and flow sensors are provided for sensing the temperature and flow of fluids at various locations within the water heater 100.
  • a controller 38 is responsive to the sensors for controlling flow of fluid through the water heater 100 for safety and to allow the water heater to operate in various modes.
  • a first temperature sensor 39 is soldered to the first fluid conduit 204 adjacent its point of return to the storage reservoir 1 for sensing the temperature of the de-oxygenated water.
  • a second temperature sensor 40 is also soldered to the first fluid conduit adjacent its point of return to the storage reservoir 1 for sensing the temperature of the de-oxygenated water.
  • a third temperature sensor 45 is provided for sensing the temperature of the de-oxygenated water downstream of the second heat exchanger 101.
  • a first flow sensor in the form of a thermal sensor 41, which senses flow based on the relative temperatures of the mains water and the de-oxygenated water, is located between the mains water circuit 300 and the de-oxygenated water circuit 200, adjacent the first inlet 19, for sensing the flow of mains water.
  • the first flow sensor 41 is soldered to a conduit of the mains fluid heating circuit and to a conduit of the de-oxygenated water circuit.
  • the controller 38 is also responsive to controls of the hydronic heating circuit (not shown). Should the water heater 100 ever overheat due to a component failure, the controller 38 receives a signal from the third temperature sensor 45 and fuel to the burner 5 is stopped.
  • the controller 38 is adapted to close the first valve 14 in response to the first flow sensor 41 sensing flow of mains water, to thereby prevent de-oxygenated water from flowing through the first heat exchanger 101.
  • the controller 38 is adapted to open a fuel valve 23 for supplying fuel to the burner 5 and to actuate the burner 5 in response to the first flow sensor 41 sensing flow of mains water and the first temperature sensor 39 indicating a temperature below a first predetermined value of approximately 82 0 C.
  • the controller 38 is adapted to close the fuel valve 23 and deactivate the burner 5 in response to the first flow sensor 41 sensing flow of mains water and the first temperature sensor 39 indicating a temperature above a second predetermined value of approximately 85°C.
  • the controller 38 is adapted to open the first valve 14 in response to the first flow sensor 41 sensing a stoppage of mains water flow, to thereby allow de-oxygenated water to flow through the first heat exchanger 11 to scavenge residual heat in the first heat exchanger 11.
  • the controller 38 is adapted to open fuel valve 23 and actuate the burner 5 in response to the first flow sensor 41 sensing a stoppage of mains water flow and the second temperature sensor 40 indicating a temperature below a third predetermined value of approximately 65°C.
  • the controller 38 is adapted to close the fuel valve 23 and deactivate the burner 5 in response to the first flow sensor 41 sensing a stoppage of mains water flow and the second temperature sensor 40 indicating a temperature above a fourth predetermined value of approximately 8O 0 C.
  • the controller 38 is adapted to actuate both the first pump 28 and the second pump 29, and to open the third valve 31 and close the second valve 35, in response to the hydronic heating system (not shown) being activated.
  • the controller 38 is adapted to close the third valve 31 and deactivate the second pump 29 if the mains water temperature at the first outlet 27 falls below a user's preset desired hot water supply temperature.
  • the three pipe-in-pipe heat exchangers 11, 101, 25, the storage reservoir 1 and all other components of the water heater 100 are fixed to a central chassis 3, which is suspended inside a housing 4. Insulation 42 and 43 is fitted to the housing 4 to reduce heat losses. The insulation also supports the chassis 3 and prevents the internal water heater components from making any contact with the housing 4. Accordingly, the potential for any heat losses through the housing 4 is reduced.
  • the chassis 3 is fitted with air channels 44, which provide an air gap to allow heat from the back of the combustion chamber 8, and first heat exchanger 11 to heat the air in the gap via contact with the chassis 3.
  • the heated air is subsequently drawn by a forced draft fan 6 located in the combustion chamber 8, whilst the burner 5 is on, into the combustion chamber 8 and forced up and through the first 11 and second 101 heat exchangers.
  • the chassis 3 has vent holes 46 in its top and base to enhance the thermal rise of heat whilst the burner 5 is actuated.
  • the housing 4 has an air inlet vent 7.
  • the air inlet vent 7 is orientated vertically and forms an air heat trap which reduces the potential for any heat losses during maintenance mode.
  • An outlet duct 15 is also provided for the exhaust of cooled combustion products.
  • the outlet duct 15 is also orientated vertically to form an air heat trap, which reduces the potential for heat loss.
  • mains water heating mode as shown in Figure 1, mains water enters the water heater 100 via inlet 19.
  • the controller 38 opens the fuel valve 23 and ignites the burner 5.
  • the controller 38 also closes solenoid valve 14 to prevent de-oxygenated water from flowing through the first heat exchanger 11.
  • the mains water passes through the first heat exchanger 11, where it is heated by exchanging heat with hot combustion products rising through the first heat exchanger 11 and by exchanging heat with the relatively hot, stationary, de-oxygenated water in pipes 12a of the heat exchanger 12.
  • the mains water absorbs most of the heat from combustion products rising through the first heat exchanger 1 1.
  • the partially heated mains water then passes into the second heat exchanger 101, where it is heated by exchanging heat with the relatively hot de-oxygenated water therein. Some of the mains water also bypasses the second heat exchanger 101 via portion 301 of the second fluid circuit 300.
  • the mains water passing through the second heat exchanger 101 and through portion 301 continues on through to the third heat exchanger 25, where the mains water is further heated by exchanging heat with the de-oxygenated water therein.
  • the third heat exchanger 25 provides the largest temperature rise for the mains water during its passing through the water heater 100. However, the other heat exchangers 11, 101 also impart significant heat to the mains water. After exiting the third heat exchanger 25, the heated mains fluid passes out of the water heater 100 via outlet 27.
  • controller 38 opens solenoid valve 14 to allow the de-oxygenated water to cycle through the first heat exchanger 11 to scavenge any residual heat in still rising combustion products.
  • the burner 5 also remains on, until the sensor 40 indicates a de-oxygenated water temperature of 80°C, to reinstate heat lost from the de- oxygenated water during heating of the mains water.
  • mains water s trapped in the second fluid circuit 300 after a tap (not shown) downstream of the water heater 100 is closed, will continue to heat and expand.
  • pressure in the second fluid circuit 300 is released by allowing small injections of mains water into the first fluid circuit 200 through expansion valve 36.
  • These small injections of mains water also serve to top up the water level in the first fluid circuit 200o to account for any losses. If the water level in the first fluid circuit 200 becomes too large, however, it simply overflows via overflow 37 of the storage reservoir 1.
  • the water heater 100 In maintenance heating mode, as shown in Figure 2, the water heater 100 is not being called upon to supply hot mains water and the controller 38 opens solenoid valve 14 in response to sensor 41 sensing no flow of mains water.
  • the de-oxygenated water iss continuously cycled through the first 11, second 101 and third 25 heat exchangers.
  • the burner 5 is periodically actuated and deactivated by the controller 38 in response to feedback from sensor 40 to maintain the de-oxygenated water at a temperature of between 65 and 8O 0 C.
  • Figure 3 shows a hydronic heating mode of the water heater 100.
  • the controller 38 closes solenoid valve 35 to prevent de-oxygenated water from flowing from the storage reservoir 1 directly into the first heat exchanger 11.
  • the controller 38 also opens solenoid valve 31 and actuates the second pump 29.
  • the closed solenoid valve 35 ensures that only the returned (cooled) de-oxygenated waterS from the fourth heat exchanger 32 is circulated though the first heat exchanger 11. This ensures that the temperature differential between the combustion products in the first heat exchanger 11 and the de-oxygenated water (which has been cooled by the hydronic system in plate heat exchanger 32) is the largest achievable and consequently the highest possible combustion / thermal efficiency can be maintained during hydronic heating0 mode.
  • the de-oxygenated water is continuously cycled through the first 11, second 101 and third 25 heat exchangers.
  • the burner 5 is periodically actuated and deactivated by the controller 38 in response to feedback from sensor 40 to maintain the de-oxygenated water at a temperature of between 65 and 80°C.
  • the controller 38 is also fitted with a mains water priority sensor (not shown), which automatically disconnects supply to the hydronic heating system should the mains water outlet temperature ever drop below the user's desired preset hot water temperature.
  • the cut-off setting for the hydronic heating system is also adjustable to suit the operating temperature of the hydronic system and ensures that the domestic mains water is always given priority over the hydronic heating system should the unit not be able to supply sufficient energy to run both functions.
  • the expansion valve 36 operates in the same manner in the hydronic heating mode as in the maintenance heating mode.
  • Figure 19 shows a circuit drawing of the water heater's electronic control system. In addition to a number of the abovementioned control components, Figure 19 also shows mains power MP, a plurality of switches SwI, Sw2, Sw3, Sw4 and Sw5, an air pressure switch SWA P , a flame proof ignitor I, and a hydronic heating thermostat TR.
  • the controller 38 actuates the forced draft fan 6 to draw combustion air into a space around the combustion chamber 8 and then through the fan 6 where the combustion air is mixed with burner fuel for ignition.
  • This flow path of the incoming air ensures that the exterior surfaces of both the combustion chamber 8 and the fins 12c of the first heat exchanger 11 are air cooled.
  • cooler air inside the bottom of the housing 4 is drawn into vent holes 46 in the bottom of the chassis 3, rises up between the chassis 3 and the storage reservoir 1 and exits into the top of the housing 4 via vent holes 46 in the top of the chassis 3. This air movement prevents the combustion chamber 8 and the storage reservoir 1 from overheating during combustion.
  • the heated cooling air is then redirected back into the combustion chamber 8, and through the second 101 heat exchanger and then through the first heat exchanger 11, via the forced draft fan 6.
  • high temperature combustion products 9 shown as vertical arrows, are forced up to make contact with the second heat exchanger 101 at the top of the combustion chamber 8.
  • the high temperature combustion products 9 heat exchange with the de-oxygenated water in the outer pipe 10b, which is always flowing when the burner 5 is on, and the mains water in the inner pipe 10a of the second heat exchanger 101, which only flows when hot mains water is being consumed.
  • combustion products 13 that have passed through the second heat exchanger 101, and have heat exchanged with the de-oxygenated water in the outer pipe 10b, are now significantly cooler. These cooler combustion products 13 then rise and pass through the first heat exchanger 11, where they heat exchange predominantly with the mains water in the outer thermally conductive pipes 12b.
  • the combustion products 13 cool in the first heat exchanger 11, they form condensation droplets on the surface of the vertically orientated heat exchanging fins 12. As shown in Figures 1-3 and 5, the droplets flow vertically down the fins 12 of the first heat exchanger 11 and collect in a condensation bath 20 at the base of the first heat exchanger 11. The condensation then flows through a drain outlet 21 in the base of the condensation bath 20 and out of the water heater 100 via a drain pipe 22.
  • the condensation bath 20 is positioned so that it is not in contact with any hot surfaces or in the path of any high temperature combustion products which ensures that the condensate will not re-evaporate or form a vapour.
  • the condensate liquid drains from the water heater 100 at a relatively low temperature.
  • the installer opens the expansion valve 36 by pulling on a lever at the top of the valve 36. As shown in Figure 18, this injects mains pressure water into the de- oxygenated water circuit 200 as shown by the arrows, which demonstrate the filling / priming flow path of the mains water into the de-oxygenated water circuit 200. As can be seen in Figure 18, the mains water injected from the expansion valve 36 flows into the de- oxygenated water pipe 25b of the third heat exchanger 25 in a reverse direction to the normal (pump) flow direction.
  • the mains water flows through the third heat exchanger 25 and the second heat exchanger 101 and forces all the air out of the fluid conduits 204 and 200 as it enters the storage reservoir 1.
  • the flowing mains water fills the storage reservoir 1 until the installer notices that water is flowing out of the overflow outlet 37, which indicates that the storage reservoir 1 is full and the third heat exchanger 25 is primed and has no air inside it.
  • the installer connects the power to the water heater 100 which automatically starts a preset / programmed cold start sequence.
  • the cold start sequence is preset into the controller 38 and initiates the following purging sequence of the water heater 100 prior to an ignition sequence for lighting the burner 5.
  • the controller 38 opens solenoid valve 14 and activates pump 28 for a set period of time (between 3 and 10 minutes) to enable priming of the first heat exchanger 11 and remove any air that is still present in the de-oxygenated pipes 12a of the first heat exchanger 11.
  • the configuration of the storage reservoir 1 and the first heat exchanger 11 is such that it causes the water in the storage reservoir 1 to automatically siphon through the first heat exchanger 11. Also, with the aid of the pump 28, during the cold start purging period, the water stored in the storage reservoir 1 automatically purges the first heat exchanger 11 of air and fills it with the water from storage reservoir 1.
  • the ignition sequence for burner 5 commences after the cold start purging sequence is completed.
  • the combustion fan 6, the gas valve 23 and the circulation pump 28 are simultaneously actuated and the water heater 100 reverts to its controller 38 to govern all operational modes, as shown in Figure 19.
  • the water heater 100 can be manually reset to the cold start mode, by an activation switch on the electronic controller 38, to re-prime the water heater 100, for example after drainage of the de-oxygenated water circuit 200 or storage reservoir 1 for inspection or repair.
  • the pipe-in-pi ⁇ e configuration allows for both the mains water and de-oxygenated water to be utilised as a conduit medium for heat transfer, which provides a high efficiency performance in mains water heating, maintenance and hydronic heating modes.
  • the pipe-in-pipe configuration enables the water heater to suffer virtually no negative effect in terms of longevity if the water supply is corrupted with impurities, as the mains water circuit 300, which potentially contains impurities, is separated from the de-oxygenated water circuit 200 and consequently the potential for scaling is significantly reduced.
  • the de-oxygenated water in the water heater 100 is not replaced and is constantly re-circulated between the storage reservoir 1 and the heat exchangers 11, 101, 25. Accordingly, minimal topping up of the de-oxygenated water is required, which thereby reduces the probability of the de-oxygenated water being contaminated.
  • hydronic heating mode by isolating and delivering the returned (cooled) de- oxygenated water from the return line 207 from the fourth heat exchanger 32 directly into the first heat exchanger 1 l, a large temperature differential is created with the combustion products 13. This large temperature differential can again produce a high efficiency performance.
  • the operating temperature of the heating system has a direct bearing on the efficiency of the water heater 100 in hydronic heating mode. If the hydronic heating system temperature is set above 8O 0 C, the water heater will provide a thermal / combustion efficiency close to
  • the water heater 100 can provide high efficiency combustion / thermal performance (condensing) of between 90 and 95%.
  • the de-oxygenated water in pipes 12a of the first heat exchanger 12 remains static, when the water heater 100 is in a water heating mode, to ensure that the cold mains water can recover / absorb the bulk of the heat energy from the hot combustion products 13.
  • the ability of the water heater 100 to continually cool the first heat exchanger 11 in circumstances whereby the burner 5 is cycled on and off, by continuously cycling cold mains water through the first heat exchanger 11.
  • the air flow path inside the water heater 100 ensures that heat losses from the combustion chamber 8 are re-directed back to the combustion chamber 8, where the heat is recovered via the first 11 and second 101 heat exchangers.
  • the inlet and outlet ports 201, 202, 203 from the storage reservoir 1 all penetrate via the reservoir's horizontal top lid, so as not to contact de- ⁇ xygenated water within the reservoir 1. By positioning the exit and entry points of the inlet and outlets 201, 202, 203 in the air gap 2 at the top of the reservoir 1, the potential for leaks to occur is reduced. This design also enables a variety of alternate materials to be used for the reservoir 1.
  • the relatively large 15°C differential between the cut-in and cut-out temperature settings of sensor 40 ensures that the water heater 100 performs only one recovery burn sequence after a mains domestic water draw off, a hydronic heating draw off, or a maintenance burn.
  • flow sensor 41 senses mains water flow by a thermal reading and not a flow reading, it can operate at any mains domestic water flow rate or pressure.
  • the heater 100 is able to maintain a consistent hot mains water output due to the heat energy stored in the relatively hot de-oxygenated water stored in the reservoir 1, which is pumped through the various heat exchangers 11, 101, 25 to heat the mains water until the burner 5 has activated.
  • the first thermally conductive pipe can be adapted to carry the mains water and the second thermally conductive pipe can be adapted to carry the de-oxygenated water;
  • the third thermally conductive pipe can be adapted to carry the de-oxygenated water and the fourth thermally conductive pipe can be adapted to carry the mains water;
  • the fifth thermally conductive pipe can be adapted to carry the de-oxygenated water and the sixth thermally conductive pipe can be adapted to carry the mains water; • the gas burner can be replaced with an electric burner, an oil burner or another type of fuel burner;
  • the fourth heat exchanger can be a radiator panel, air convector (forced draft or natural convection), or underfloor / slab heating coils;
  • the water heater preferably only has one gas input rate, which is the maximum rate as determined by the burner fuel valve 23 settings.
  • gas or oil management systems can be applied to the water heater;
  • the atmospheric pressure storage reservoir can be replaced with a pressurised storage reservoir governed by a conventional pressure and temperature relief/ safety valve; • the upper and lower limits of the various sensors can be adjusted based on the user's requirements and/or operating parameters of the water heater (eg. desired hot water output temperature, cold mains water input temperature); and/or
  • the third heat exchanger 25 can be placed in an exhaust path of combustion products exhausted from the first heat exchanger 11.
  • a second embodiment of a water heater 400 comprising a storage reservoir 401 for storing de-oxygenated water for use as a heating fluid.
  • the pressure within the storage reservoir is atmospheric.
  • the storage reservoir includes an overflow 402.
  • the heater 400 also includes a combustion chamber 403 housing a gas burner 404 for heating the de-oxygenated water.
  • a first heat exchanger 405, for exchanging heat between the de-oxygenated water and mains water, is located outside of the storage reservoir 401.
  • a first fluid circuit 406 connects the storage reservoir 401 with the first heat exchanger 405 for carrying de-oxygenated water from the storage reservoir 401, through the first heat exchanger 405 and back to the storage reservoir 401, as shown in Figure 23.
  • the return pipe 407 to the first fluid circuit 406 from the storage reservoir 401 causes the returning de-oxygenated water to mix with the de-oxygenated water inside the storage reservoir 401.
  • the de-oxygenated water within the first fluid circuit 406 is recycled during operation of the water heater 400.
  • a second fluid circuit 410 connects a first inlet 411 for mains water to a first outlet 412 for heated mains water via the first heat exchanger 405. The mains water and de-oxygenated water are not mixed during operation of the water heater 400.
  • the first heat exchanger 405 includes a pipe-in-pipe heat exchanger 413 having a plurality of first thermally conductive pipes 414a for containing the de-oxygenated water.
  • the first thermally conductive pipes 414a are each located within a respective second thermally conductive pipe 414b for containing the mains water.
  • the first thermally conductive pipes 414a are connected in parallel and the second thermally conductive pipes 414b loop backward and forward through the first heat exchanger 405.
  • the second thermally conductive pipes 414b include a first (upper) group of pipes connected in parallel to a second (lower) group of pipes.
  • the first heat exchanger 405 is located above the gas burner 404, such that combustion products from the gas burner 404 rise toward the first heat exchanger to heat the first heat exchanger 405.
  • the combustion products enter the first heat exchanger 405 at a temperature in the range of approximately 100° C to 160°C, dependent on the water heater's temperature settings and burner fuel input rate.
  • the first heat exchanger 405 also includes an array of fins 415 for absorbing heat from the burner combustion products and transferring the absorbed heat to the mains water and/or de-oxygenated water in the first heat exchanger 405.
  • a second heat exchanger 416 is located below the first heat exchanger 405, such that combustion products passing the second heat exchanger 416 rise toward the first heat exchanger 405 to heat the first heat exchanger 405.
  • the second heat exchanger 416 also includes an array of fins 417 for absorbing heat from the burner combustion products and transferring the heat to the de-oxygenated water in the portion of the first fluid circuit 406 passing through the second heat exchanger 416.
  • a third heat exchanger 409 is immersed in the deoxygenated water in the storage reservoir 401.
  • the third heat exchanger 409 is located downstream, in the second fluid circuit 410, of the first heat exchanger 405.
  • the third heat exchanger 409 is adapted to exchange heat between the de-oxygenated water and the mains water.
  • the third heat exchanger 409 also includes a pipe-in-pipe heat exchanger having a series of third thermally conductive pipes 409a for containing the mains water.
  • the third thermally conductive pipes 409a are located within two fourth thermally conductive pipes 409b, which contain hot de-oxygenated water.
  • the hot de-oxygenated water in the pipes 409b is drawn directly from the storage reservoir 401, via inlet bleed holes 408 and inlets 420.
  • An expansion valve 422 is provided between the second fluid circuit 410 and the first fluid circuit 406 to allow mains fluid to pass from the second fluid circuit 410 into the first fluid circuit 406 when pressure within the second fluid circuit 410 increases to a predetermined level.
  • a first pump 423 is provided for pumping de-oxygenated water through the first fluid circuit 406.
  • a drain tap 424 is also provided in the first fluid circuit 406 to allow drainage of the de-oxygenated water for servicing.
  • the drain tap 424 is connected to expansion valve 422 and, upon opening, allows de-oxygenated water to drain from the first fluid circuit 406 and storage reservoir 401.
  • an outlet 425 is provided in the storage reservoir 401 to allow for supply of the de-oxygenated water to a fourth plate-type heat exchanger 427, via a third fluid circuit 426, for exchanging heat between the de-oxygenated water and fluid in an external hydronic heating circuit (not shown).
  • An inlet 425a is provided in the first fluid circuit 406 to allow for the return of de-oxygenated water from the fourth heat exchanger 427.
  • the inlet 425a feeds into the first fluid circuit 406 upstream from the first heat exchanger 405.
  • a second pump 434 is provided in the third fluid circuit for pumping de-oxygenated water through the first 406 and third 426 fluid conduits and the fourth heat exchanger 427.
  • thermostat sensors 429 and 430 are provided for sensing the temperature and flow of fluids at various locations within the water heater 400.
  • the first thermostat sensor 429 is fitted to the first fluid circuit 406 inside the first fluid conduit 421 downstream from the second heat exchanger 416 and above storage reservoir 401 for sensing the temperature of the de-oxygenated water in the first fluid circuit 406 and storage reservoir 401.
  • a controller (not shown) is responsive to the thermostat sensor 429 for activating and de- activating the burner 404.
  • the second thermostat sensor 430 is fitted to the second fluid circuit 410 inside the second fluid conduit 431 adjacent, and in physical contact with, the first fluid conduit 421 at a point of return to the storage reservoir 401, for sensing the temperature of the mains water.
  • the controller (not shown) is responsive to the thermostat sensor 430 for activating and deactivating pump 423 upon sensing temperature change in the mains water flowing through the second fluid circuit 410.
  • a safety cut-out switch 432 is provided for sensing the temperature of the de-oxygenated water downstream of the second heat exchanger 416. Should the water heater 400 ever overheat due to a component failure, the safety cut out switch 432 will stop the supply of fuel to the burner 404.
  • thermostat sensor 429 In response to thermostat sensor 429 sensing a de-oxygenated water temperature below a first predetermined value of approximately 82° C, the controller (not shown) is set to open a fuel valve 433 for supplying fuel to the burner 404 and to actuate the burner 404 and pump 423. In response to thermostat sensor 429 sensing a de-oxygenated water temperature above a second predetermined value of approximately 85 0 C, the controller is set to close the fuel valve 433, deactivate burner 404 and stop the pump 423.
  • the controller In response to sensor 430 sensing a mains water temperature below a first predetermined value of approximately 50°C, the controller (not shown) is set to activate pump 423. In response to thermostat sensor 430 sensing a mains water temperature above a second predetermined value of approximately 55°C, the controller (not shown) is set to deactivate pump 423. The controller (not shown) responds to feedback from both sensors 429 and 430 independently. As shown in Figure 24, a hydronic heating controller (not shown) is adapted to actuate pump 423, a second pump 434, and a third pump 435 in response to the hydronic heating system (not shown) being activated. The hydronic heating controller is adapted to deactivate both the second pump 434 and third pump 435 if the mains water temperature at the first outlet 412, as shown in Figure 22, falls below a user's preset desired hot water supply temperature.
  • the two pipe-in-pipe heat exchangers 405 and 409, the storage reservoir 401 and all other components of the water heater 400 are fixed to a central chassis 436, which is suspended inside a housing 437.
  • Insulation 438 and 439 is fitted to the housing 437 to reduce heat losses.
  • the insulation 438, 439 also supports the chassis 436 and prevents the internal water heater components from making any contact with the housing 437 using the same principles as shown in FIGURES 14, 15, 16, and 17 of the first embodiment. Accordingly, the potential for any heat losses through the housing 437 is reduced.
  • the chassis 436 is fitted with air channels 440, which provide an air gap to allow heat from the back of the combustion chamber 403, and first heat exchanger 405 to heat the air in the air gap via contact with the chassis 436.
  • the heated air is subsequently drawn by a forced draft fan 441 connected to the combustion chamber 403, whilst the burner 404 is on, into the combustion chamber 403 and forced up and through the second 416 and first 405 heat exchangers.
  • the housing 437 has an air inlet vent 442.
  • the air inlet vent 442 is orientated vertically and forms an air heat trap which reduces the potential for any heat losses during a maintenance mode.
  • An outlet duct 443 is also provided for the exhaust of cooled combustion products.
  • the outlet duct 443 is also orientated vertically to form an air heat trap, which reduces the potential for heat loss.
  • mains water heating mode as shown in Figures 22 and 35, mains water enters the water heater 400 via inlet 411.
  • the controller (not shown) actuates pump 423 and starts circulating hot de-oxygenated water through the first fluid circuit 406.
  • the flowing mains water in the second fluid circuit 410 Prior to entering the water heater 400, the flowing mains water in the second fluid circuit 410 is cold and heat exchanges with the hot de-oxygenated water which is being pumped through both pipe-in-pipe heat exchangers 409 and 413.
  • the flowing mains water is heated by the flowing de-oxygenated water and the de-oxygenated water is accordingly cooled by the flowing mains water.
  • Thermostat sensor 429 senses the resulting drop in de- oxygenated water temperature and causes the controller 500 to open the fuel valve 433 and ignite the burner 404.
  • the mains water passes through the first heat exchanger 405, where it is heated by exchanging heat with hot combustion products rising through the first heat exchanger 405 and by exchanging heat with the hot, flowing de-oxygenated water in pipes 414a of the heat exchanger 413.
  • the de-oxygenated water in the first heat exchanger 405 is flowing and also provides heat to the flowing mains water in the first heat exchanger 405. Heat is applied to the flowing mains water from both the hot combustion products and the flowing hot de-oxygenated water inside the first heat exchanger 405.
  • the flowing mains water is cold, it can cool the combustion products flowing through the first heat exchanger 405 to an extent that a high combustion efficiency in the range of 90 to 99% can be achieved, dependent on the ambient temperature and water temperature that the heater 400 is operating in. A combustion efficiency above 90% can create large volumes of condensate in the first heat exchanger 405.
  • the partially heated mains water then passes into the third heat exchanger 409, where it is heated by exchanging heat with the hot de-oxygenated water that is circulating through the second heat exchanger 416, storage reservoir 401 and third heat exchanger 409.
  • Both pipe in pipe heat exchangers 409 and 413 provide temperature rise for the mains water during its passing through the water heater 400.
  • the heated mains fluid passes out of the water heater 400 via outlet 412.
  • thermostat sensor 429 allows the de-oxygenated water to continue to cycle through the first fluid circuit 406 and heat exchangers 405 and 409 to scavenge any residual heat in the still rising combustion products from the combustion chamber 403.
  • the burner 404 also remains on, until the thermostat sensor 429 senses a de-oxygenated water temperature of 85 0 C, to reinstate heat lost from the de- oxygenated water during heating of the mains water.
  • the controller (not shown) closes the supply of fuel to the fuel valve 433 and the burner 404 shuts down.
  • the controller (not shown), in response to feedback from thermostat sensor 430, may maintain the pump 423, which circulates the de-oxygenated water through the first fluid circuit 406 after the burner 404 has shut down, until the temperature in the mains water adjacent to the sensor 430 rises to its shut-off setting of approximately 55 0 C.
  • the burner 404 may reactivate whilst the mains water is reheating until the thermostat sensor 430 reaches its pre set shut-off temperature setting of approximately 55°C.
  • thermostat sensor 429 gains full control of the pump 423 and simultaneously activates and deactivates the pump 423, fuel valve 433 and fan 441 upon feedback from thermostat sensor 429, which only senses the temperature of the de-oxygenated water circulating through the first fluid circuit 406.
  • thermostat sensor 429 is responding to and reading the hottest de-oxygenated water in the first fluid circuit 406, which is downstream from the second heat exchanger 416. This method of temperature control causes the de-oxygenated water in the storage reservoir 401 to be maintained at a lower temperature of between 5 0 C and 10°C below the actual shut-off temperature setting of thermostat sensor 429.
  • the cooler mains water which is trapped in the second fluid circuit 410 after a tap (not shown) downstream of the water heater 400 is closed, will continue to heat and expand.
  • pressure in the second fluid circuit 410 is released by allowing small injections of mains water into the first fluid circuit 406 through expansion valve 422.
  • These small injections of mains water also serve to top up and maintain the water level in the first fluid circuit 406 to account for any losses. If the water level in the first fluid circuit 406 becomes too large, it simply overflows via overflow 402 of the storage reservoir 401.
  • Figure 35 shows a wiring diagram of the water heater 400 when in mains water heating heating mode, with sensor 429 sensing a de-oxygenated water temperature below 82°C whilst sensor 430 is sensing mains water below 50°C. Accordingly sensor 430 connects the pump 423 to the active power line 510 which is independent and not influenced by sensor 429.
  • the components shown in the wiring diagram are the gas fuel valve controller 500, mains power input 510, a 7.5 Amp fuse 512, pump 423, forced draft fan 441, burner thermostat sensor 429a, burner thermostat switch 429b, pump thermostat sensor 430a, pump thermostat switch 430b, safety cut-out sensor 432a, safety cut-out switch 432b, , gas line inlet 602, active inlet 603, neutral inlet 604a, neutral wire 604b, earth inlet 605a, earth wire 605b, ignition wire 606 and combustion flames 607.
  • the water heater 400 In maintenance heating modes, as shown in Figures 23 36 and 37, the water heater 400 is not being called upon to supply hot mains water.
  • the de-oxygenated water is periodically cycled through the first 405, second 416 and third 409 heat exchangers.
  • the burner 404 and pump 423 are periodically actuated and deactivated simultaneously in response to feedback from thermostat sensor 429 to maintain the de-oxygenated water in the storage reservoir 401 at a temperature of between 68°C and 70°C.
  • Figure 36 shows the wiring diagram of the water heater 400 when in maintenance heating mode and with thermostat sensor 429 sensing a de-oxygenated water temperature above its shut off setting.
  • the water heater 400 is in a standby maintenance mode with no water being circulated through the unit and burner 404 and pump 423 off.
  • the components shown in the wiring diagram are the gas fuel valve controller 500, mains power input 510, a 7.5 Amp fuse 512, pump 423, forced draft fan 441, burner thermostat sensor 429a, burner thermostat switch 429b, pump thermostat sensor 430a, pump thermostat switch 430b, safety cut-out sensor 432a, safety cut-out switch 432b, gas line inlet 602, active inlet 603, neutral inlet 604a, neutral wire 604b, earth inlet 605a, earth wire 605b and ignition wire 606.
  • Figure 37 shows the wiring diagram of the water heater 400 when in maintenance heating mode and with thermostat sensor 429 sensing a de-oxygenated water temperature below its shut off setting.
  • Pump 423 is receiving its active power from and active line 510 via the gas controller which also supplies power to the combustion fan 441 and both are activated and deactivated by controlling thermostat 429.
  • the components shown in the wiring diagram are the gas fuel valve controller 500, mains power input 510, a 7.5 Amp fuse 512, pump 423 , forced draft fan 441 , burner thermostat sensor 429a, burner thermostat switch 429b, pump thermostat sensor 430a, pump thermostat switch 430b, safety cut-out sensor 432a, safety cut-out switch 432b, gas line inlet 602, active inlet 603, neutral inlet 604a, neutral wire 604b, earth inlet 605a, earth wire 605b, ignition wire 606 and combustion flames 607.
  • Figure 24 shows a hydronic heating mode of the water heater 400.
  • the hydronic controller (not shown) simultaneously activates pumps 434, 435 and 423.
  • Pump 434 prevents de-oxygenated water from flowing from the storage reservoir 401 directly into the first heat exchanger 405, because the flow of water through the third fluid circuit 426 feeds into the first fluid circuit 406 between the tank reservoir 401 and the first heat exchanger 405 and is sufficient to supply the demand from pump 423. This ensures that the temperature differential between the combustion products in the first heat exchanger 405 and the de-oxygenated water (which has been cooled by the hydronic system in plate heat exchanger 427) is the largest achievable and consequently the highest possible combustion / thermal efficiency can be maintained during hydronic heating mode.
  • the de-oxygenated water is continuously cycled through the first heat exchanger 405, the second heat exchanger 416, into the storage reservoir 401, exiting via outlet 425, which directs the de-oxygenated water into pump 434, which pumps the deoxygenated water through the plate heat exchanger 427.
  • the burner 404 is periodically actuated and deactivated by thermostat sensor 429 in response to the temperature of the de-oxygenated water circulating through the first 406 and third fluid circuit 426.
  • the hydronic controller (not shown) is also fitted with a mains water priority sensor (not shown), which automatically shuts down pumps 434 and 435 should the mains water outlet temperature ever drop below the user's desired preset hot water temperature.
  • the cut-off setting for the hydronic heating system is also adjustable to suit the operating temperature of the hydronic system and ensures that the domestic mains water is always given priority over the hydronic heating system should the unit not be able to supply sufficient energy to run both functions.
  • the expansion valve 422 operates in the same manner in the hydronic heating mode as in the maintenance heating mode and does not inject any water into the first fluid circuit 406.
  • Ventilation of the water heater 400 will now be described with reference to Figure 21.
  • the controller (not shown) actuates a forced draft fan 441 to draw combustion air into a space below the combustion chamber 403 and then through the fan 441, where the combustion air is mixed with burner fuel for ignition.
  • This flow path of the incoming air enables the exterior surfaces of the lower part of the combustion chamber 403 and other heat sensitive internal components, such as components of the fuel valve 433, fan 441, pump 423 and thermostat sensors 429 and
  • Cooler air inside the bottom of the housing 437 is drawn through vent holes 444 via air inlet vent 442.
  • the air vent holes 444 direct the incoming air directly onto components of the fuel valve 433, fan 441, pump 423 and thermostat sensors 429 and 430 whilst the burner 404 is in operation.
  • the heated cooling air is then re-directed back into the combustion chamber 403, through the second 416 heat exchanger, and then through the first heat exchanger 405, via the forced draft fan 441.
  • High temperature combustion products 445 shown as vertical arrows, are forced up to make contact with the second heat exchanger 416 at the top of the combustion chamber 403.
  • the high temperature combustion products 445 heat exchange with the de- oxygenated water in the heat exchanger 416, which is always flowing when the burner 404 is on.
  • combustion products 446 that have passed through the second heat exchanger 416 have heat exchanged with the de-oxygenated water in the second heat exchanger 416, and have been significantly cooled. These cooler combustion products 446 then rise and pass through the first heat exchanger 405, where they heat exchange predominantly with the mains water in the outer thermally conductive pipes 414b (as shown in Figure 21).
  • combustion products 446 pass through the first heat exchanger 405, they enter flue outlet duct 443, which forces them vertically down to the flue outlet 447, which directs the cooled combustion products 448 horizontally out and away from a front cover 449 of the housing 437.
  • the combustion products 446 cool in the first heat exchanger 405, they form condensation droplets on the surface of the vertically orientated heat exchanging fins 415.
  • the condensation droplets flow vertically down the fins 415 of the first heat exchanger 405 and collect in a condensation bath 450 at the base of the first heat exchanger 405.
  • the condensation then flows through a drain outlet (not shown) in the base of the condensation bath 450 and out of the water heater 400 via a drain pipe (not shown).
  • the condensation bath 450 is positioned so that it is not in contact with any hot surfaces or in the path of any high temperature combustion products which ensures that the condensate will not re-evaporate or form a vapour.
  • the condensate liquid drains from the water heater 400 at a relatively low temperature.
  • the installer opens the expansion valve 422 by pulling on a lever 451 at the top of the valve 422. This injects mains pressure water into the de-oxygenated first fluid circuit 406, as shown by the arrows, which demonstrate the filling / priming flow path of the mains water into the de-oxygenated first fluid circuit 406.
  • the mains water injected from the expansion valve 422 flows into the de-oxygenated first fluid circuit 406 and takes two paths at junction 452 upon entering the de-oxygenated first fluid circuit 406.
  • the outlet of expansion valve 422 is set at an angle so that the majority of the mains water entering and filling the de-oxygenated first fluid circuit 406 is directed at pump 423 to ensure that the first heat exchanger 405 can be purged of air that is driven out by the rising mains water as it makes its way through the de-oxygenated first fluid circuit 406, the first heat exchanger 405 and ultimately into the storage reservoir 401 via the third heat exchanger inlets 420 and bleed holes 408 in a reverse direction to the normal pump 423 flow direction.
  • FIG 25 shows that, as the storage reservoir 401 starts to fill up with mains water that enters via the third heat exchanger 409 and the first fluid circuit return pipe 407, the outlet from the first fluid circuit return pipe 407 becomes submerged by the rising mains water in the storage reservoir 401, as indicated by the water level 453.
  • Figure 27 shows the water heater 400 at the completion of the filling sequence.
  • Mains water can be seen flowing out of the overflow outlet 402, which indicates that the storage reservoir is full of water and that first heat exchanger 405 and the third heat exchanger 409 are purged of air and full of mains water.
  • the thermostat sensor 429 (shown in Figure 22) will instantly sense that the water heater 400 is cold and cause the controller (not shown) to activate the fuel valve 433, which will initiate an ignition sequence which causes pump 423 and fan 441 to start simultaneously.
  • the pump 423 will draw water from the storage reservoir 401 through the first fluid circuit 406 via the third heat exchanger 419 and first heat exchanger 405. As the pump 423 activates, all the residual air which was previously trapped in the combustion chamber 403 and the first fluid circuit return pipe 407 is driven out by the water being pumped into the storage reservoir 401. As the water is heated in the first fluid circuit the oxygen present in the water is driven out and ultimately becomes de-oxygenated.
  • the above described embodiment provides the following benefits: •
  • the pipe-in-pipe configuration allows for both the mains water and de-oxygenated water to be utilised as a conduit medium for heat transfer, which provides a high efficiency performance in mains water heating, maintenance and hydronic heating modes.
  • the pipe-in-pipe configuration enables the water heater to suffer virtually no negative effects in terms of longevity if the water supply is corrupted with impurities, as the mains water circuit 410, which potentially contains impurities, is separated from the de-oxygenated water circuit 406 and consequently the potential for scaling is significantly reduced, because the mains water circuit 410 does not into contact with the high temperature combustion products 445, as shown in Figure 22.
  • the de-oxygenated water in the water heater 400 is not replaced and is constantly re-circulated between the storage reservoir 401 and the heat exchangers 405, 416, 409. Accordingly, minimal topping up of the de-oxygenated water is required, which thereby reduces the probability of the de-oxygenated water being contaminated.
  • the combustion / thermal efficiency in maintenance mode is between 90% and 94%, dependent on the temperature setting of de-oxygenated water in the storage reservoir 401.
  • hydronic heating mode by isolating and delivering the returned (cooled) de- oxygenated water from the return line 454 from the fourth heat exchanger 427 directly into the first heat exchanger 405, a large temperature differential is created with the combustion products 446. This large temperature differential can again produce a high efficiency performance.
  • the operating temperature of the heating system has a direct bearing on the efficiency of the water heater 400 in hydronic heating mode. If the hydronic heating system temperature is set above 80°C, the water heater will provide a thermal / combustion efficiency close to 90%. If the hydronic heating system is set under 60-50°C, or the returning water from the hydronic heating system is lower than 45-50°C, the water heater 400 can provide high efficiency combustion / thermal performance (condensing) of between 90 and 95%.
  • the burner 404 will cycle on and off to ensure an appropriate /desired hot mains water temperature can be supplied.
  • the air flow path inside the water heater 400 ensures that heat losses from the combustion chamber 403 are re-directed back into the combustion chamber 403, where the heat is recovered via the first 405 and second 416 heat exchangers.
  • the inlet and outlet ports from the storage reservoir 401 all penetrate via the reservoir's horizontal top lid, so as not to contact de-oxygenated water within the reservoir 401.
  • the exit and entry points of the inlet and outlets in the air gap 455, as shown in Figure 22, at the top of the reservoir 401 the potential for leaks to occur is reduced.
  • This design also enables a variety of alternate materials to be used for the reservoir 401.
  • the use and function of dual thermostat sensors 429 and 430 also prevents nuisance burns (stair casing), which can occur in single thermostat systems.
  • thermostat sensor 430 senses mains water flow by a thermal reading and not a flow reading, it can operate at any mains domestic water flow rate or pressure.
  • the heater 400 is able to maintain a consistent hot mains water output due to the heat energy stored in the relatively hot de- oxygenated water stored in the reservoir 401, which is pumped through the various heat exchangers 405, 416, 409 to heat the mains water until the burner 404 has activated.
  • the mixing of de-oxygenated water returning to the reservoir 401 with de- oxygenated water already in the reservoir 401 is enhanced by the internal currents inside reservoir 401, which are caused by the velocity of the circulation pump 423 and the direction of the returning de-oxygenated water, which is set by the return pipe 407. This mixing ensures that the reservoir 401 supplies de-oxygenated water of a consistent temperature, which reduces temperature fluctuations in the hot flowing mains water whilst burner 404 is cycling on and off in mains water heating mode.
  • the first thermally conductive pipe 414a can be adapted to carry the mains water and the second thermally conductive pipe 414b can be adapted to carry the de-oxygenated water;
  • the thermally conductive pipe 409a can be adapted to carry the de-oxygenated water and the thermally conductive pipe 409b can be adapted to carry the mains water;
  • the gas burner 404 can be replaced with an electric burner, an oil burner or another type of fuel burner;
  • the fourth heat exchanger 427 can be a radiator panel, air convector (forced draft or natural convection), or underfloor / slab heating coils; • the water heater 400 preferably only has one gas input rate, which is the maximum rate as determined by the burner fuel valve 433 settings. However, alternative gas or oil management systems (modulating input rates) can be applied to the water heater 400;
  • the atmospheric pressure storage reservoir 401 can be replaced with a pressurised storage reservoir governed by a conventional pressure and temperature relief/ safety valve; and/or
  • the upper and lower limits of the various sensors can be adjusted based on the user's requirements and/or operating parameters of the water heater (eg. desired hot water output temperature, cold mains water input temperature).

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Abstract

La présente invention concerne un dispositif de chauffage de fluide (100) comprenant un réservoir de stockage (1) destiné à stocker un fluide de chauffage, un brûleur (5) destiné à chauffer le fluide de chauffage et un premier échangeur de chaleur (1) situé à l'extérieur dudit réservoir de stockage (1). Le dispositif de chauffage (100) comprend également un premier circuit de fluide (200) raccordant le réservoir de stockage (1) au premier échangeur de chaleur (11) pour transporter le fluide de chauffage depuis le réservoir de stockage (1), à travers le premier échangeur de chaleur (11) et à nouveau vers le réservoir de stockage (1), et un second circuit de fluide (300) raccordant une première entrée (19) pour le fluide de réseau à une première sortie (27) pour le fluide de réseau chauffé par le biais du premier échangeur de chaleur (11). Le premier échangeur de chaleur (11) est adapté pour échanger la chaleur entre ledit fluide de chauffage et ledit fluide de réseau.
PCT/AU2008/001109 2007-08-01 2008-07-31 Dispositif de chauffage de fluide Ceased WO2009015435A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN2008801061838A CN101878399A (zh) 2007-08-01 2008-07-31 流体加热器
EP08772731A EP2288856A1 (fr) 2007-08-01 2008-07-31 Dispositif de chauffage de fluide
AU2008281327A AU2008281327A1 (en) 2007-08-01 2008-07-31 Fluid heater
US12/671,420 US20100282440A1 (en) 2007-08-01 2008-07-31 Fluid Heater

Applications Claiming Priority (4)

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AU2007203612 2007-08-01
AU2007203612A AU2007203612A1 (en) 2007-08-01 2007-08-01 Condensing water and hydronic heater
AU2008901467A AU2008901467A0 (en) 2008-03-26 Fluid heater
AU2008901467 2008-03-26

Publications (1)

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WO2009015435A1 true WO2009015435A1 (fr) 2009-02-05

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US (1) US20100282440A1 (fr)
EP (1) EP2288856A1 (fr)
CN (1) CN101878399A (fr)
AU (1) AU2008281327A1 (fr)
WO (1) WO2009015435A1 (fr)

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WO2017135814A1 (fr) * 2016-02-01 2017-08-10 Intergas Heating Assets B.V. Chauffe-eau, évacuation de gaz de combustion pour celui-ci et procédé de chauffage d'un fluide

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DE102015225581A1 (de) * 2015-12-17 2017-06-22 Convotherm Elektrogeräte GmbH Verfahren zum Betreiben eines gewerblichen Gargeräts
CA3107299A1 (fr) 2020-01-31 2021-07-31 Rinnai America Corporation Accessoire d`event pour un chauffe-eau sans reservoir
UA122651C2 (uk) * 2020-02-13 2020-12-10 Костянтин Леонідович Серебреников Двоконтурний електричний котел (варіанти)
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WO2017135814A1 (fr) * 2016-02-01 2017-08-10 Intergas Heating Assets B.V. Chauffe-eau, évacuation de gaz de combustion pour celui-ci et procédé de chauffage d'un fluide
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US11359837B2 (en) 2016-02-01 2022-06-14 Intergas Heating Assets B.V. Hot water appliance, flue gas discharge therefor and method for heating a fluid

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AU2008281327A1 (en) 2009-02-05
CN101878399A (zh) 2010-11-03
US20100282440A1 (en) 2010-11-11
EP2288856A1 (fr) 2011-03-02

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