GB2464162A - Auxiliary heat exchange unit when used in conjunction with a hot water cylinder of a hot water supply system - Google Patents

Auxiliary heat exchange unit when used in conjunction with a hot water cylinder of a hot water supply system Download PDF

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Publication number
GB2464162A
GB2464162A GB0901186A GB0901186A GB2464162A GB 2464162 A GB2464162 A GB 2464162A GB 0901186 A GB0901186 A GB 0901186A GB 0901186 A GB0901186 A GB 0901186A GB 2464162 A GB2464162 A GB 2464162A
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United Kingdom
Prior art keywords
heat exchange
hot water
water
cylinder
auxiliary heat
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GB0901186A
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GB0901186D0 (en
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Brian A Sampson
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Individual
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Individual
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Classifications

    • 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
    • F24D17/00—Domestic hot-water supply systems
    • F24D17/0036—Domestic hot-water supply systems with combination of different kinds of heating means
    • 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
    • F24D11/00—Central heating systems using heat accumulated in storage masses
    • F24D11/002—Central heating systems using heat accumulated in storage masses water heating system
    • F24D11/004—Central heating systems using heat accumulated in storage masses water heating system with conventional supplementary heat source
    • 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
    • F24D12/00—Other central heating systems
    • F24D12/02—Other central heating systems having more than one heat source
    • 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
    • F24D17/00—Domestic hot-water supply systems
    • F24D17/0036—Domestic hot-water supply systems with combination of different kinds of heating means
    • F24D17/0052—Domestic hot-water supply systems with combination of different kinds of heating means recuperated waste heat and conventional heating means
    • F24D17/0057—Domestic hot-water supply systems with combination of different kinds of heating means recuperated waste heat and conventional heating means with accumulation of the heated water
    • 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
    • F24D17/00—Domestic hot-water supply systems
    • F24D17/0036—Domestic hot-water supply systems with combination of different kinds of heating means
    • F24D17/0063—Domestic hot-water supply systems with combination of different kinds of heating means solar energy and conventional heaters
    • F24D17/0068—Domestic hot-water supply systems with combination of different kinds of heating means solar energy and conventional heaters with accumulation of the heated water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D20/0034—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material
    • F28D20/0039—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material with stratification of the heat storage material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
    • 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
    • F24D2200/00—Heat sources or energy sources
    • F24D2200/04—Gas or oil fired boiler
    • 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
    • F24D2200/00—Heat sources or energy sources
    • F24D2200/08—Electric heater
    • 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
    • F24D2200/00—Heat sources or energy sources
    • F24D2200/14—Solar energy
    • 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
    • Y02B10/00—Integration of renewable energy sources in buildings
    • Y02B10/20—Solar thermal
    • 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
    • Y02B10/00—Integration of renewable energy sources in buildings
    • Y02B10/70—Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
    • 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]
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/14—Thermal energy storage
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Heat-Pump Type And Storage Water Heaters (AREA)

Abstract

An auxiliary heat exchange unit 20 used in conjunction with a hot water cylinder 10 of a hot water supply system comprises a first tank 24, a second tank 26 and a central tank 28. The first 24 and second 26 tanks are linked by heat exchange pipes (30, fig 2) passing through the central tank 28 and is in heat exchange relationship with liquid in the central tank 28. First tank 24 has an inlet for liquid heated by an auxiliary heat source 22 and the liquid passes through the heat exchange pipes (30) to the second tank 26. Second tank 26 has an outlet for discharge of the liquid therefrom, and the central tank 28 has at least one inlet for water from a water supply and an outlet for the water that has been heated by the heat exchange pipes (30) for supply as preheated water to the hot water cylinder 10. Heat exchange pipes (30) may be copper and have external fins. Central tank 28 may have a temperature sensor located in a first and second portion and an electric heating element maintains the water temperature in the central tank 28 above the legionella bacillus incubation temperature. Auxiliary heat source 22 may be a boiler, heat pump, waste heat from air conditioning or refrigeration units, waste water or a solar panel.

Description

TITLE
Auxiliary Heat Exchange Unit for a Domestic or Industrial Hot Water Supply
DESCRIPTION
The invention relates to hot water supplies, which may be for domestic, commercial or small industrial applications. The invention provides an auxiliary heat exchange unit which transfers heat indirectly from an external auxiliary heat source into an in situ hot water cylinder. The auxiliary heat exchange unit is particularly well suited to hot water supply systems which draw heat from two or more complementary heat sources. One heat source will be the primary heat source, and may be a boiler powered by gas, electricity, oil, solid fuel or other available fuel or a heat pump. The other heat source or sources may be any constant or intermittent heat source, including any of the above, or solar panels, or sources of waste heat from an industrial plant, from an air conditioning unit, from a biological waste digester or from ground heat. In a domestic situation, the primary heat source may be a domestic central heating boiler and the auxiliary heat source may be one or more solar panels or the back boiler of a domestic fire.
BACKGROUND ART
In conventional domestic hot water supply systems heated water from a boiler is circulated by a pump or by gravity feed, through a heat exchange coil in a hot water cylinder. That hot water cylinder is generally made from copper or stainless steel, and is lagged to retain the heat. Supply water enters the hot water cylinder at or near the bottom, and exits at or near the top after being heated by heat exchange with the hot water from the boiler in the heat exchange coil of the hot water cylinder.
If an auxiliary heat source, such as one of those listed above, is added to the installation, then heat from the liquid heated in the auxiliary heat source has to be passed to the water in the hot water cylinder. Typically this has involved either inserting an extra coil into the cylinder, or replacing the entire hot water cylinder with one that has two or more heat exchange coils. One such coil is for the heated water from the boiler and the other(s) is (are) for the heated water or other heat exchange liquid from the auxiliary heat source(s). These modifications to the hot water installation can be expensive, disruptive, and inefficient.
When an extra coil is inserted into the in situ cylinder, either an existing electric immersion heater is removed or an extra hole has to be cut into the cylinder. When the immersion heater is removed, the cylinder can be damaged beyond repair, but even if damage to the cylinder is avoided, the electric immersion heater is no longer available as an alternative heat source. When a new hole is cut, the cylinder can be damaged beyond repair, and new flanges may be prone to leakage, either immediately or at any later time. The extra coil is restricted by the width of the hole and the length that can pass into the cylinder without hitting either the bottom or side of the cylinder or the coil already in there.
When either the existing hole or a new hole is located at the top of the cylinder, the extra coil must be inserted vertically, with both the supply and return pipes for the heat exchange liquid entering the cylinder from above. The new heat exchange liquid in the extra coil will pass down into the cylinder. As it goes down it will give off heat.
As it returns it will pick up heat. The extra coil therefore becomes less effective as the target water is heated. As the return pipe of the extra coil passes through the top of the cylinder, it passes in heat exchange contact with water heated by the primary heat source. If the auxiliary heat source is above the cylinder, eg a solar panel, heated water can rise through the return pipe of the extra coil and trick the additional heat source into seeing this heat as being new heat and make the source falsely become active.
When either the existing hole or a new hole is located in the side of the cylinder, the new coil is restricted by the diameter of the hole and the width of the cylinder. A new hole cannot be made alongside the area directly covered by the in situ coil.
Instead of inserting an extra coil into the in situ cylinder, the entire hot water cylinder may be replaced. Often the original cylinder which is removed attracts only scrap value. The new hot water cylinder may be less efficient than the original because in order to fit two heat exchange coils into the hot water cylinder, the size of the main coil carrying the heated boiler water may have to be reduced so as to allow for the introduction of a second heat exchange coil carrying the water or other heat exchange liquid from the auxiliary heat source. Alternatively the replacement cylinder may have to be larger than the original. Otherwise the second heat exchange coil introduced alongside the principal heat exchange coil carrying hot water from the boiler displaces an equivalent volume of water from the hot water cylinder so as to reduce the effective cylinder capacity. The result can be a hot water cylinder with inadequate storage capacity for the intended use. There is therefore a clear need for a hot water system which can make use of a possibly intermittent source of auxiliary heat to increase the efficiency of the overall system, without reducing the capacity or efficiency of the hot water cylinder and without requiring replacement of that cylinder.
THE [NVENTION The invention provides an auxiliary heat exchange unit cylinder as defined in claim I herein. The unit itself may be constructed as a single integral unit, but essentially it consists of a top tank, a central tank and a bottom tank, with the top and bottom tanks being linked by an array of heat exchange pipes passing through the central tank in heat exchange contact with liquid in the central tank. That auxiliary heat exchange unit is used in conjunction with a domestic, small commercial or light industrial hot water supply as described and illustrated later in this specification.
Heat from the auxiliary heat source is used to heat a heat exchange liquid, which may be water, and that heat exchange liquid is passed into the top tank of the auxiliary heat exchange unit through a liquid inlet, down into the bottom tank through the one or more heat exchange pipes, and out from the bottom tank through a liquid outlet. The heat exchange liquid may be then recirculated if desired to the auxiliary heat source, using either convection or a pumped circulation system.
The heat exchange pipes pass through the central tank in heat exchange contact with water in that central tank. That water in the central tank is heated by the heat exchange, and is passed from an outlet at or near the top of the central tank as supply water to the principal hot water cylinder of the hot water supply system. The hot water supply system thus receives preheated water as its supply water, and that preheated water can be further heated as required by the principal heat source, to supply hot water at the required temperature.
The invention also provides a domestic, commercial or industrial hot water supply system according to claim 7 herein.
The auxiliary heat exchange unit may be a thermally lagged copper or stainless steel unit made from materials similar to those used for conventional domestic hot water cylinders, or alternatively may be made from a thermoplastic or thermosetting resin.
Even a resin cylinder is preferably thermally lagged. It does not have to have the same water capacity as conventional hot water cylinder, and preferably is considerably narrower in diameter than a conventional hot water cylinder, and optionally shorter in height, with a much smaller water capacity than the principal hot water cylinder which it supplies. Preferably it is proportioned as a tall and narrow unit, with the central tank occupying most of the unit height so as to take maximum benefit from the natural convection flow of the supply water through the central tank.
Even when that supply water is pumped into the principal water cylinder as supply water, the flow and the heat exchange characteristics within the central tank are improved by that particular tall narrow shape. Other shapes are, however, quite feasible, especially when accompanied by pumped circulation of the heat exchange liquid from the auxiliary heat source.
The heat exchange pipes connecting together the top and bottom tanks are preferably externally finned so as to increase their heat exchange efficiency as they contact the water in the central tank over an increased area. Externally finned copper pipes are most preferred.
The auxiliary heat exchange unit is preferably provided with one or two sensor pockets, one in an upper portion of the central tank and the other in a lower portion of the central tank. Each sensor pocket houses a sensor for monitoring the temperature of the water in the adjacent part of the central tank. Advantageously the central tank is provided with an electric heating element for maintaining the temperature of the supply water in the central tank above the incubation temperature of legionella bacillus. The reason for this electric immersion heater is that if the unit is left in an empty property, for example, with no boiler running as the primary heat source, the auxiliary heat source may cause the water in the auxiliary tank to heat up to a temperature of 30°C or thereabouts, being a temperature conducive to the growth of legionella bacillus. The result would be a risk of Legionellosis or Legionnaire's disease when water is subsequently drawn from taps in the property. If the central tank is provided with a small immersion heater sufficient to heat the relatively small amount of water in the auxiliary tank to a sufficiently high temperature, even only intermittently, then the danger of Legionnaire's disease is minimised.
Advantageously the auxiliary heat exchange unit is provided with a thermal cut-out, thermally activated to interrupt the heat exchange flow of liquid heated by the auxiliary heat source, to protect the unit and cylinder from the possibility of over-heating and subsequent raised pressure.
The auxiliary heat exchange unit according to the invention can be used when the auxiliary heat source is a solar panel or a number of solar panels. That heat source is often sufficient to provide all the hot water required in a domestic house or small commercial or industrial unit during the hottest part of the day when the sun is unobscured by cloud, but a boiler is needed as the main heat source for when there is poor sunlight to heat the solar panels. During hot summer weather the main boiler may not be needed at all with all required hot water being adequately heated by the solar panels, and stored in the cylinder. The boiler preferably automatically cuts in when there is a demand for hot water and the supply water from the cylinder is at a temperature below the desired usage temperature.
Instead of solar energy, the auxiliary heat source may be heat from a domestic chimney or back boiler, or waste heat from an air conditioning system, from an industrial plant, or from a biological waste digester, or it may be simply ground heat.
Any source of auxiliary heat may be used, since the water outlet temperature from the principal hot water cylinder is always going to be under the control of the domestic or commercial boiler serving as the primary heat source.
DRAWINGS
Figure 1 is a schematic illustration of a hot water supply installation comprising a principal hot water cylinder and an auxiliary heat exchange unit according to the invention; Figure 2 is a section through an auxiliary heat exchange unit according to the invention; Figures 3a to 3g are an array of seven alternative water supply circuits displayed in a conventional schematic manner to illustrate to flexibility of the incorporation of an auxiliary heat exchange unit according to the invention into a variety of hot water installation circuits.
Figures 3a' to 3g' are the corresponding pumped versions of Figures 3a to 3g.
Referring first to Figure 1, a complete hot water supply installation is illustrated. The installation comprises a conventional hot water cylinder 10 which has an internal heat exchange coil 12 supplied with hot water heated by a boiler indicated schematically as B. Water is drawn off from the top of the cylinder 10 through pipe 14 to taps situated throughout the building in which the hot water supply is installed. The cylinder may be an open cylinder with a header tank above (not illustrated) to create the necessary pressure of water to the taps, or it may be a pressurised cylinder accepting water at mains pressure. The different alternative circuit details indicating open or pressurised cylinders are omitted for simplicity.
Feed water is supplied to the cylinder 10 through a pipe 16 from an auxiliary heat exchange unit 20 according to the invention. The different possible alternative supply installations are briefly described below with reference to Figures 3a to 3g and Figures 3a' to 3g. Water is supplied to the auxiliary heat exchange unit 20 through a pipe 18.
Heat exchange liquid such as water or a non-aqueous heat exchange fluid is circulated through the auxiliary heat exchange unit 20 from an auxiliary heat source 22 such as a solar panel. The flow may be siphonic convection flow or may be pumped. Figure 1 shows a pump P by way of example, denoting a pumped flow.
The internal construction of the auxiliary heat exchange unit 20 is better illustrated in Figure 2. The unit, made of metal or plastic, is preferably lagged (not shown) with a thermal insulation material such as a foam covering. It comprises a top tank 24, a bottom tank 26 and a central tank 28. The top tank 24 has a liquid inlet for the heat exchange liquid from the auxiliary heat source. The bottom tank has a liquid outlet for discharge of the heat exchange liquid therefrom, in the case of Figure 1 for recirculation by the pump P to the solar panel 22. The top and bottom tanks 24 and 26 are linked by an array of externally fumed heat exchange pipes 30 which pass through the central tank 28 in heat exchange contact with water in the central tank.
Figures 3a to 3g show alternative installations which are possible using the auxiliary heat exchange unit 20 (AUX 20) according to the invention. The different feed and return arrangements are as follows: In Figure 3a AUX 20 is below cylinder 10. Cold supply is to AUX 20. Heated water from AUX 20 is supplied to the inlet of cylinder 10. Cool water from the drain of cylinder 10 is linked to the cold inlet supply to AUX 20.
In Figure 3b AUX 20 is below the cylinder 10. Cold supply is to AUX 20. Heated water from AUX 20 is supplied to the inlet of cylinder 10. Cool water from the drain of cylinder 10 is supplied to a separate inlet supply to AUX 20.
In Figure 3c AUX 20 is below the cylinder 10. Cold supply is to AUX 20. Heated water from AUX 20 is supplied to the inlet of cylinder 10. Cool water from the cylinder 10 is drawn through the cylinder 10 inlet and linked to the cold inlet supply to AUX 20.
In Figure 3d the AUX 20 is below the cylinder 10. Cold supply is to cylinder 10.
Cool water from the cylinder 10 is supplied to the inlet of AUX 20. Heated water from AUX 20 is supplied to the drain of cylinder 10.
In Figure 3e the AUX 20 is level with the cylinder 10. Cool water from the drain of cylinder 10 is heated in AUX 20 and is supplied to cylinder 10 via an Essex flange.
In Figure 3f the AUX 20 is level with the cylinder 10. Cool water from the drain of cylinder 10 is linked to the cold supply which is to AUX 20. Water heated in AUX is supplied to cylinder 10 via a Surrey flange through a pipe extended down towards the base of cylinder 10.
In Figure 3g the AUX 20 is level with the cylinder 10. Cool water from the drain of AUX 20 is linked to the cold supply which is to AUX 20. Water heated in AUX 20 is supplied to cylinder 10 via a reduced pipe passing through a tee connector and extending down towards the base of cylinder 10..
Figures 3a' to 3g' are pumped versions of Figures 3a to 3g.
In every case, the auxiliary heat source such as the solar panel 22 illustrated in Figure 1 is used to preheat the supply water fed to the hot water cylinder 10. At times that preheating may be sufficient to mean that no further heating of the water is required at all from the boiler B. At other times the boiler B may be used to raise the water temperature further, to a proper usage temperature. In all cases however, it will be appreciated that the hot water cylinder 10 has received virtually no modification as a result of the addition of the auxiliary heat source to the hot water system, and it retains its original water capacity.

Claims (14)

  1. CLAIMSI. An auxiliary heat exchange unit for use in conjunction with a principal hot water cylinder of a hot water supply system, which auxiliary heat exchange unit comprises: a top tank; a central tank; and a bottom tank, the top and bottom tanks being linked by an array of heat exchange pipes passing through the central tank in heat exchange contact with liquid in the central tank; wherein the top tank includes a liquid inlet for liquid heated by an auxiliary heat source, which liquid passes down through the heat exchange pipes to the bottom tank; the bottom tank includes a liquid outlet for the discharge of the liquid therefrom; and the central tank includes at or near its base an inlet(s) for water from a water supply and at or near its top an outlet for that water, heated by heat exchange with the heat exchange pipes, for supply as preheated water to the principal hot water cylinder.
  2. 2. An auxiliary heat exchange unit according to claim 1, wherein the heat exchange pipes have external fins to increase their heat exchange contact with liquid in the central tank.
  3. 3. An auxiliary heat exchange unit according to claim 2, wherein the heat exchange pipes are externally finned copper pipes.
  4. 4. An auxiliary heat exchange unit according to any preceding claim, further comprising a sensor pocket in the upper portion of the central tank, housing a sensor for monitoring the temperature of water in that portion of the central tank.
  5. 5. An auxiliary heat exchange unit according to any preceding claim, further comprising a sensor pocket in the lower portion of the central tank, housing a sensor for monitoring the temperature of water in that portion of the central tank.
  6. 6. An auxiliary heat exchange unit according to any preceding claim, further comprising an electric heating element in the central tank, for maintaining the temperature of water in the central tank above the incubation temperature of legionella bacillus.
  7. 7. A domestic or industrial hot water supply system comprising: a principal hot water cylinder; a primary heat source for heating water in the principal hot water cylinder; an auxiliary heat exchange unit connected to supply preheated water to a supply side of the principal hot water cylinder; and an auxiliary heat source for heating a heat exchange liquid supplied to an inlet of the auxiliary heat exchange unit, wherein the heat exchange liquid is arranged to pass through the auxiliary heat exchange unit in counter current flow and in heat exchange relationship with water in the auxiliary heat exchange unit which is supplied as the preheated water to the principal hot water cylinder.
  8. 8. A hot water system according to claim 7, wherein the primary heat source is a boiler or an electric immersion heater.
  9. 9. A hot water system according to claim 7 or claim 8, wherein the auxiliary heat source is a solid fuel boiler, a heat pump, a source for obtaining waste heat from an air conditioning or refrigeration unit or from a water drain, or a solar heat exchange panel.
  10. 10. A hot water system according to claim 9, wherein the auxiliary heat source is a solar heat exchange panel. -12-
  11. 11. A hot water system according to any of claims 7 to 10, wherein the auxiliary heat exchange unit is mounted at a lower level than the principal hot water cylinder and the supply of preheated water to the principal hot water cylinder is a convection supply.
  12. 12. A hot water system according to any of claims 7 to 10, wherein the auxiliary heat exchange unit is mounted alongside the principal hot water cylinder but with an outlet for the preheated water at a level below the top of the principal hot water cylinder, and the supply of preheated water to the principal hot water cylinder is a convection supply.
  13. 13. A hot water system according to any of claims 7 to 10, wherein the auxiliary heat exchange unit is mounted at a lower level than, or alongside, or above, the principal hot water cylinder and the supply of preheated water to the principal hot water cylinder is a pumped supply.
  14. 14. A hot water system according to any of claims 7 to 13, substantially as described herein with reference to the drawings.Amendments to the Claims have been filed as followsCLAIMS1. A hot water supply system comprising a principal hot water cylinder and an auxiliary heat exchange unit, wherein the auxiliary heat exchange unit comprises: a top tank; a central tank; and a bottom tank, the top and bottom tanks being linked by an array of heat exchange pipes passing through the central tank in heat exchange contact with water in the central tank which is connected to flow in a circulatory fluid path to and from the principal hot water cylinder; wherein the top tank includes a liquid inlet for liquid heated by an auxiliary heat source, which liquid passes down through the heat exchange pipes to the bottom tank; the bottom tank includes a liquid outlet for the discharge of the liquid therefrom; and the central tank includes at or near its base an inlet for water from a water supply and at or near its top an outlet for that water, heated by heat exchange with the heat exchange pipes, for supply as preheated water to the principal hot water cylinder.2. A hot water supply system according to claim 1, wherein the heat exchange pipes have external fins to increase their heat exchange contact with liquid in the central tank. * * * S. S * .**3. A hot water supply system according to claim 2, wherein the heat exchange pipes are externally finned copper pipes.SS.....* 4. A hot water supply system according to any preceding claim, further * .*S * . : comprising a sensor pocket in the upper portion of the central tank, housing a sensor : 30 for monitoring the temperature of water in that portion of the central tank.5. A hot water supply system according to any preceding claim, further comprising a sensor pocket in the lower portion of the central tank, housing a sensor for monitoring the temperature of water in that portion of the central tank.6. A hot water supply system according to any preceding claim, further comprising an electric heating element in the central tank, for maintaining the temperature of water in the central tank above the incubation temperature of legionella bacillus.7. A hot water supply system according to any receding claim, further comprising: a primary heat source for heating water in the principal hot water cylinder; and an auxiliary heat source for heating a heat exchange liquid supplied to an inlet of the auxiliary heat exchange unit, wherein the heat exchange liquid is arranged to pass through the auxiliary heat exchange unit in counter current flow and in heat exchange relationship with water in the auxiliary heat exchange unit which is supplied as the preheated water to the principal hot water cylinder.8. A hot water supply system according to claim 7, wherein the primary heat source is a boiler or an electric immersion heater.9. A hot water supply system according to claim 7 or claim 8, wherein the auxiliary heat source is a solid fuel boiler, a heat pump, a source for obtaining waste heat from an air conditioning or refrigeration unit or from a water drain, or a solar heat exchange panel.S S...* 10. A hot water supply system according to claim 9, wherein the auxiliary heat I..* ** source is a solar heat exchange panel.*...*. * .11. A hot water supply system according to any of claims 7 to 10, wherein the auxiliary heat exchange unit is mounted at a lower level than the principal hot water cylinder and the supply of preheated water to the principal hot water cylinder is a convection supply.12. A hot water supply system according to any of claims 7 to 10, wherein the auxiliary heat exchange unit is mounted alongside the principal hot water cylinder but with an outlet for the preheated water at a level below the top of the principal hot water cylinder, and the supply of preheated water to the principal hot water cylinder is a convection supply.13. A hot water supply system according to any of claims 7 to 10, wherein the auxiliary heat exchange unit is mounted at a lower level than, or alongside, or above, the principal hot water cylinder and the supply of preheated water to the principal hot water cylinder is a pumped supply.14. A hot water supply system according to any preceding claim, substantially as described herein with reference to the drawings. *.** * * * ** * S... * .S..... * . * S * * S *S * S.SI S
GB0901186A 2009-01-24 2009-01-24 Auxiliary heat exchange unit when used in conjunction with a hot water cylinder of a hot water supply system Withdrawn GB2464162A (en)

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GB0901186A GB2464162A (en) 2009-01-24 2009-01-24 Auxiliary heat exchange unit when used in conjunction with a hot water cylinder of a hot water supply system

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2475149A (en) * 2009-11-03 2011-05-11 Peter Thomas Dearman Solar hot water system comprising two tanks
EP4253847A1 (en) 2022-03-28 2023-10-04 Mitsubishi Electric Corporation System and method for providing domestic hot water

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2256778A1 (en) * 1974-01-03 1975-08-01 Sun Ventures Inc Elimination of tubular hot-spots in heat exchange reactors - by dividing outer casing into individually temp.-controlled compartments
US4126122A (en) * 1977-01-24 1978-11-21 Bross Theodore D Solar hot water booster and exchanger for use therein
US4296729A (en) * 1980-02-04 1981-10-27 Suntime, Inc. Solar hot water heating system
US4619311A (en) * 1985-06-28 1986-10-28 Vasile Carmine F Equal volume, contraflow heat exchanger
US20060011193A1 (en) * 2004-07-16 2006-01-19 Jiangming Rong Water pre-heating arrangement

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2256778A1 (en) * 1974-01-03 1975-08-01 Sun Ventures Inc Elimination of tubular hot-spots in heat exchange reactors - by dividing outer casing into individually temp.-controlled compartments
US4126122A (en) * 1977-01-24 1978-11-21 Bross Theodore D Solar hot water booster and exchanger for use therein
US4296729A (en) * 1980-02-04 1981-10-27 Suntime, Inc. Solar hot water heating system
US4619311A (en) * 1985-06-28 1986-10-28 Vasile Carmine F Equal volume, contraflow heat exchanger
US20060011193A1 (en) * 2004-07-16 2006-01-19 Jiangming Rong Water pre-heating arrangement

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2475149A (en) * 2009-11-03 2011-05-11 Peter Thomas Dearman Solar hot water system comprising two tanks
EP4253847A1 (en) 2022-03-28 2023-10-04 Mitsubishi Electric Corporation System and method for providing domestic hot water

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