Methods and systems and apparatus to support reduced energy and water usage
The system addresses the inefficiencies of heat pumps in smaller properties by integrating a heat exchanger, thermal storage, and electric heating, optimizing energy and water use for efficient hot water delivery, reducing waste and installation complexity.
Patent Information
- Authority / Receiving Office
- AU · AU
- Patent Type
- Applications
- Current Assignee / Owner
- OCTOPUS ENERGY HEATING LTD
- Filing Date
- 2024-04-24
- Publication Date
- 2026-07-23
Smart Images
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Abstract
Description
Technical field The present disclosure variously relates to methods and apparatus, for installations including an in-building hot water supply system, that support reduced energy and water usage. Background Worldwide, there is a shortage of potable water. Water shortages are now commonly reported around the world, and although it might be thought that such issues only affect "hot" countries and continents, that is no longer the case. The European Environment Agency reports that water shortages or water stress is a problem that affects millions of people around the world, including over 100 Million people in Europe. About 88.2 % of Europe's freshwater use (drinking and other uses) comes from rivers and groundwater, while the rest comes from reservoirs (10.3 %) and lakes (1.5 %), which makes these sources extremely vulnerable to threats posed by over-exploitation, pollution and climate change. Consequently, there is an urgent need reduce domestic water usage. In Europe, on average, 144 litres of freshwater per person per day is supplied for household consumption, but much of this water is "wasted" through carelessness and poor choices of taps, showers, and appliances. Allied to the need to reduce water consumption is the need to reduce domestic energy consumption, particularly given that (at least in Europe) around 75% of heating and cooling is still generated from fossil fuels while only 22% is generated from renewable energy. According to Directive 2012 / 27 / EU, buildings represent 40 % of the final energy consumption and 36% of the CO2 emissions of the European Union. The EU Commission report of 2016 "Mapping and analyses of the current and future (2020 - 2030) heating / cooling fuel deployment (fossil / renewables)" concluded that in EU households, heating and hot water alone account for 79% of total final energy use (192.5Mtoe). The EU Commission also report that, "according to 2019 figures from Eurostat, approximately 75% of heating and cooling is still generated from fossil fuels while only 22% is generated from renewable energy. To fulfil the EU's climate and energy goals, the heating and cooling sector must sharply reduce its energy consumption and cut its use of fossil fuels. Heat pumps (with energy drawn from the air, the ground or water) have been identified as potentially significant contributors in addressing this problem. In many countries, there are policies and pressures to reduce carbon footprint. For example, in the UK in 2020 the UK Government published a whitepaper on a Future Homes Standard, with proposals to reduce carbon emissions from new homes by 75 to 80% compared to existing levels by 2025. In addition, it was announced in early 2019 that there would be a ban on the fitment of gas boilers to new homes from 2025. It is reported that in the UK at the time of filing 78% of the total energy used for the heating of buildings comes from gas, while 12% comes from electricity. The UK has a large number of small, 2 -3 bedroom or less, properties with gas-fired central heating, and most of these properties use what are known as combination boilers, in which the boiler acts as an instantaneous hot water heater, and as a boiler for central heating (space heating). Combination boilers are popular because they combine a small form factor, provide a more or less immediate source of "unlimited" hot water (with 20 to 35kW output), and do not require hot water storage. Such boilers can be purchased from reputable manufactures relatively inexpensively. The small form factor and the ability to do without a hot water storage tank mean that it is generally possible to accommodate such a boiler even in a small flat or house - often wall-mounted in the kitchen, and to install a new boiler with one man day's work. It is therefore possible to get a new combi gas boiler installed inexpensively. With the imminent ban on new gas boilers, alternative heat sources will need to be provided in place of gas combi boilers. In addition, previously fitted combi boilers will eventually need to be replaced with some alternative. Combination boilers generally have dimensions of from about 70cm to 200cm in height, from 420cm to 150cm in width and from 20cm to 100cm in depth, with an average internal combination boiler for a small to medium size house being about 75cm in height, 45cm in width and 50cm in depth, although, of course, those dimensions vary according to manufacturer and rated power of the boiler. With growing concerns over the environmental impact of energy consumption, there has been a recent growing interest in the use of heat pump technologies as a way of providing domestic heated water. A heat pump is a device that transfers thermal energy from a source of heat to a thermal reservoir. Although a heat pump requires electricity to accomplish the work of transferring thermal energy from the heat source to the thermal reservoir, it is generally more efficient than electrical resistance heaters (electrical heating elements) as it typically has a coefficient of performance of at least 3 or 4. This means under equal electricity usage 3 or 4 times the amount of heat can be provided to users via heat pumps compared to electrical resistance heaters. The heat transfer medium that carries the thermal energy is known as a refrigerant. Thermal energy from the air (e.g. outside air, or air from a hot room in the house) or a ground source (e.g. ground loop or water filled borehole) is extracted by a receiving heat exchanger and transferred to a contained refrigerant. The now higher energy refrigerant is compressed, causing it to raise temperature considerably, where this now hot refrigerant exchanges thermal energy via a heat exchanger to a heating water loop. In the context of heated water provision, heat extracted by the heat pump can be transferred to water in an insulated tank that acts as a thermal energy storage, and the heated water may be used at a later time when needed. The heated water may be diverted to one or more water outlets, e.g. a tap, a shower, a radiator, as required. However, a heat pump generally requires more time compared to electrical resistance heaters to get water up to the desired temperature. Although heat pumps have been proposed as a potential solution to the need to reduce reliance on fossil fuels and cut CO2 emissions, they are currently unsuited to the problem of replacing gas fired boilers in smaller domestic (and small commercial) premises for a number of technical, commercial and practical reasons. They are typically very large and need a substantial unit on the outside of the property. Thus, they cannot easily be retrofitted into a property with a typical combi boiler. A unit capable of providing equivalent output to a typical gas boiler would currently be expensive and may require significant electrical demand. Not only do the units themselves cost multiples of the equivalent gas fired equivalent, but also their size and complexity mean that installation is technically complex and therefore expensive. A storage tank for hot water is also required, and this is a further factor militating against the use of heat pumps in small domestic dwellings. A further technical problem is that heat pumps tend to require a significant time to start producing heat in response to demand, perhaps 30 seconds for self-checking then some time to heat up - so a delay of 1 minute or more between asking for hot water and its delivery. For this reason, attempted renewable solutions using heat pumps and / or solar are typically applicable to large properties with room for a hot water storage tank (with space demands, heat loss and legionella risk). An important component of domestic energy consumption stems from use of domestic hot water, both in terms of the volume of hot water used, and in terms of energy wastage through overheating of domestic hot water. Hot water wastage is also, of course, a significant contributor to the more general problem of water wastage, which also needs to be addressed if mankind is going to have a sustainable future. 2024296525 12 Mar 2026 Whether it is in a commercial or domestic setting, heated water is required throughout the day all year round. It goes without saying that the provision of heated water requires both clean water and a source of heat. To provide heated water, a heating system is provided to an often centralised water provision system to heat water up to a predetermined temperature 5 e.g. set by a user, and the heat source used is conventionally one or more electric heating elements or burning of natural gas. Generally, during periods of high energy (e.g. gas or electricity) demand utilities providers would implement a peak tariff which increases the unit cost of energy, partly to cover the additional cost of having to purchase more energy to supply to customers and partly to discourage unnecessary energy usage. Then, during periods of low 10 energy demand utilities providers would implement an off-peak tariff which lowers the unit cost of energy to incentivise customers to switch to using energy during these off-peak periods instead of peak periods to achieve an overall more balanced energy consumption over time. However, such strategies are only effective if customers are always aware of the changes in tariffs and in addition make a conscious effort to modify their energy consumption habits. 15 Since different households, workplaces and commercial spaces have different requirements and preferences for heated water usage, new ways of heated water provision are desirable in order to enable heat pumps to be a practical alternative to electrical heaters. It is to be appreciated that any discussion of documents, devices, acts, or knowledge in this specification is included to explain the context of the present invention. Further, the 20 discussion throughout this specification comes about due to the realisation of the inventor and / or the identification of certain related art problems by the inventor. Moreover, any discussion of material such as documents, devices, acts, or knowledge in this specification is included to explain the context of the invention in terms of the inventor’s knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any 25 of the material forms part of the prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein. The preceding discussion of background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general 30 knowledge as at the priority date of the application. By way of guide to interpreting the present specification, “comprises / comprising” and “includes / including” when used in this specification is taken to specify the presence of stated features, integers, steps, or components but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. Thus, unless the 2024296525 12 Mar 2026 context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, ‘includes’, ‘including’ and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. 5 Summary The invention generally provides a domestic hot water provisioning system comprising: a cold water inlet for receiving cold water from a mains supply; a hot water outlet for providing hot water on demand to a domestic hot water outlet activated by a user and connected to the cold water inlet; 10 a heat exchanger having a first inlet connected to the cold water inlet and a first outlet connected to the hot water outlet, the heat exchanger selectively heating water between the first inlet and the first outlet using a hot fluid selectively received from a hot fluid source; an electric heater for selectively heating water; a thermal storage appliance for storing heat connected to the hot water outlet; 15 a circulation pump for pumping water from the thermal storage appliance to the heat exchanger; a first flow path between the cold water inlet and the first inlet of the heat exchanger; a second flow path between the cold water inlet and a fifth flow path; a third flow path having a first part between the thermal storage appliance and the first 20 flow path and a second part between the thermal storage appliance and the fifth flow path, wherein the circulation pump is located in a return flow path in parallel with the first part of the third flow path; a fourth flow path including the electric heater in series between the first outlet of the heat exchanger and the fifth flow path; 25 the fifth flow path from the fourth flow path and the third flow path to the hot water outlet; and a controller coupled to at least the electric heater and the circulation pump for controlling operation of the hot water provisioning system in one or more operating modes including: 30 a charging mode for charging the thermal storage appliance by controlling the system to heat the thermal storage appliance, wherein the thermal storage appliance is heated to a temperature based on availability of heat to the heat exchanger, wherein the thermal storage appliance may provide hot water via the third flow path to the fifth flow path to the hot water outlet; and 2024296525 12 Mar 2026 a mixed water mode for providing hot water to the hot water outlet, the mixed water mode comprising: a) determining whether hot water is being demanded at the hot water outlet, and, if hot water is being demanded at the hot 5 water outlet, controlling the system to pass hot water from the thermal storage appliance or from the electric heater or from the heat exchanger or from a combination thereof via the fifth flow path to the hot water outlet; b) determining a temperature of the hot water at the hot water 10 outlet; c) if the hot water at the hot water outlet is determined to be hotter than a desired temperature, controlling the system to pass cold water from the cold water inlet via the second flow path, to mix with the hot water from the fourth flow path to reduce the 15 temperature of the mixed water passed via the fifth flow path to the hot water outlet; and d) repeating steps b) and c) to control the flow of cold water though the second flow path so that the temperature of the mixed water available at the hot water outlet is at or lower than the desired 20 temperature. The invention also generally provides a method of controlling a domestic hot water provisioning system, the domestic hot water provisioning system comprising: a cold water inlet for receiving cold water from a mains supply; a hot water outlet for providing hot water on demand to a domestic hot water outlet 25 activated by a user and connected to the cold water inlet; a heat exchanger having a first inlet connected to the cold water inlet and a first outlet connected to the hot water outlet, the heat exchanger selectively heating water between the first inlet and the first outlet using a hot fluid selectively received from a hot fluid source; an electric heater for selectively heating water; 30 a thermal storage appliance for storing heat connected to the hot water outlet; a circulation pump for pumping water from the thermal storage appliance to the heat exchanger; a first flow path between the cold water inlet and the first inlet of the heat exchanger; a second flow path between the cold water inlet and a fifth flow path; 2024296525 12 Mar 2026 10 15 20 25 30 a third flow path having a first part between the thermal storage appliance and the first flow path and a second part between the thermal storage appliance and the fifth flow path, wherein the circulation pump is located in a return flow path in parallel with the first part of the third flow path; a fourth flow path including the electric heater in series between the first outlet of the heat exchanger and the fifth flow path; the fifth flow path from the fourth flow path and the third flow path to the hot water outlet; and a controller coupled to at least the electric heater and the circulation pump; the method comprising the controller controlling operation of the hot water provisioning system in one or more operating modes including: a charging mode for charging the thermal storage appliance by controlling the system to heat the thermal storage appliance, wherein the thermal storage appliance is heated to a temperature based on availability of heat to the heat exchanger, wherein the thermal storage appliance may provide hot water to the hot water outlet via the third flow path to the fifth flow path to the hot water outlet; and a mixed water mode for providing hot water to the hot water outlet, the mixed water mode comprising: a) b) c) d) determining whether hot water is being demanded at the hot water outlet, and, if hot water is being demanded at the hot water outlet, controlling the system to pass hot water from the thermal storage appliance or from the electric heater or from the heat exchanger or from a combination thereof via the fifth flow path to the hot water outlet; determining a temperature of the hot water at the hot water outlet; if the hot water at the hot water outlet is determined to be hotter than a desired temperature, controlling the system to pass cold water from the cold water inlet via the second flow path, to mix with the hot water from the fourth flow path to reduce the temperature of the mixed water passed via the fifth flow path to the hot water outlet; and repeating steps b) and c) to control the flow of cold water though the second flow path so that the temperature of the mixed water 2024296525 12 Mar 2026 available at the hot water outlet is at or lower than the desired temperature. The invention further generally provides a corresponding computer program product, in the form of a computer readable medium having instructions stored thereon, which, when 5 executed by one or more processors of a controller, cause the controller to perform one or a combination of the method steps disclosed herein. Brief description of the drawings Embodiments of various aspects of the disclosure will now be described by way of example only, with reference to the accompanying drawings, in which: 10 Figure 1 is schematic system overview of an exemplary water provision system in accordance with preferred embodiments of the invention; Figure 2 is a schematic diagram showing an in-building water supply installation according to a preferred aspect of the disclosure; Figure 3 is a schematic drawing of part of an in-building water supply installation, similar 15 to that of Figure 2, showing components and flow paths; Figure 4 shows the in-building water supply installation of Figure 3, illustrating a first mode of operation; Figure 5 shows the in-building water supply installation of Figure 3, illustrating a second mode of operation; Figure 6 shows the in-building water supply installation of Figure 3, illustrating a third mode of operation; Figure 7 shows the in-building water supply installation of Figure 3, illustrating a fourth mode of operation; Figure 8 shows the in-building water supply installation of Figure 3, illustrating a fifth mode of operation; Figure 9 shows the in-building water supply installation of Figure 3, illustrating a sixth mode of operation; Figure 10 shows the in-building water supply installation of Figure 3, illustrating a seventh mode of operation; Figure 11 shows the in-building water supply installation of Figure 3, illustrating an eighth mode of operation; and Figure 12 shows the in-building water supply installation of Figure 3, illustrating a ninth mode of operation. Detailed description In addressing domestic energy consumption, it is important to consider the energy used in providing hot water, and this means taking account not just of the temperature of the water that is supplied or stored, but also the volume of hot water used. In many countries and regions that are perceived to have ample fresh water, little attention was historically paid to the amount of water used by households, and that lack of attention was largely reflected in the configuration of water supply systems and the flow rates of water outlets. It was not uncommon for bath taps to flow more than 15 litres per minute, kitchen taps with flow rates or 12 litres per minute or more, and even basin taps with flow rates of 10 litres per minute or more. Shower outlets might flow more than 15 litres per minute, about 2 / 3 of which would typically come from the hot supply. Attitudes have changed somewhat over the past two decades, as water scarcity has begun to be recognised, and as former publicly owned water suppliers have been privatised with the consequent introduction of household water meters and volume-based charging for water. Consequently, newer build dwellings tend to have taps and shower outlets with maximum flow rates about half to two thirds of those of their historical counterparts. Nevertheless, not only is it common for older dwellings still to have high flow rate taps and showers, but even more modern outlets also make it easy to use more water than is strictly necessary to wash hands, bathe, or shower. Consider a shower with a 15 litre per minute flow rate: a 12-minute shower will use 180 litres of water, and of this around 100 to 110 litres will come from the hot supply. Hot water supply temperatures will often be in the range of 50 to 60 Celsius - heated from no more than 10 Celsius, an often from a considerably colder temperature. It will be appreciated therefore that not only is a lot of water used, but also a lot of energy to heat that water. In addition, although high hot water supply temperatures of 50 to 60 Celsius have the benefit of reducing the risk of Legionella infections, there is a considerable scalding risk with temperatures in this range. In embodiments of the present techniques, cold and heated water is provided by a centralized water provision system to a plurality of water outlets, including taps, showers, radiators, etc., for a building in a domestic or commercial setting. An exemplary water provision system according to an embodiment is shown in Fig. 1. In this schematic system, the water provision system 100 comprises a control module 110, which may include one or more Machine Learning Algorithms 120. The control module 110 is communicatively coupled to, and configured to control, various elements of the water provision system, including flow control 130 for example in the form of one or more valves arranged to control the flow of water internal and external to the system, a (ground source or air source) heat pump 140 configured to extract heat from the surroundings and deposit the extracted heat in a thermal energy storage 150 to be used to heat water, and one or more electric heating elements 160 configured to directly heat cold water to a desired temperature by controlling the amount of energy supplied to the electric heating elements 160. Heated water, whether heated by the thermal energy storage 150 or heated by the electric heating elements 160, is then directed to one or more water outlets as and when needed. In the embodiments, the heat pump 140 extracts heat from the surroundings into a thermal energy storage medium within the thermal energy storage 150. The thermal energy storage medium may in addition be heated by other sources. The thermal energy storage medium is heated until it reaches a desired operation temperature, then cold water e.g. from the mains can be heated by the thermal energy storage medium to the desired temperature. The heated water may then be supplied to various water outlets in the system. In the present schematic system, the control module 110 is configured to receive input from a plurality of sensors 170-1, 170-2, 170-3,..., 170-n. The plurality of sensors 1701, 170-2, 170-3, ..., 170-n may for example include one or more air temperature sensors disposed indoor and / or outdoor, one or more water temperature sensors, one or more water pressure sensors, one or more timers, one or more motion sensors, and may include other sensors not directly linked to the water provision system 100 such as a GPS signal receiver, calendar, weather forecasting app on e.g. a smartphone carried by an occupant and in communication with the control module via a communication channel. The control module 110 is configured, in the present embodiment, to use the received input to perform a variety of control functions, for example controlling the flow of water through the flow control 130 to the thermal energy storage 150 or electric heating elements 160 to heat water. While a heat pump is generally more energy efficient for heating water compared to an electrical resistance heater, a heat pump requires time to start up as it performs various checks and cycles before reaching a normal operation state, and time to transfer sufficient amount of thermal energy into a thermal energy storage medium before reaching the desired operation temperature. On the other hand, an electrical resistance heater is generally able to provide heat more immediately. Thus, a heat pump can take longer to heat the same amount of water to the same temperature compared to an electrical resistance heater. Figure 2 shows a more detailed schematic diagram of an in-building hot water supply installation 200 having a plurality of controllable water outlets (various taps and showers that will be described more fully later), a supply of hot water 205 with at least one outlet having a controllable outflow temperature, and in a water flow path between the supply of water 205 and the plurality of controllable water outlets, at least one first temperature sensor 243 to detect the outflow temperature, at least one flow measurement device 210 and at least one flow regulator 215. A processor 240 is operatively connected to the at least one flow measurement device 210 and the at least one flow regulator 215. The illustrated water supply installation represents a dwelling with a master bathroom 221, a first en-suite shower room 222, a second en-suite shower room 223, a cloakroom 224, and a kitchen 225. The master bathroom 221 and the first en-suite shower room 222 may be on one floor of the dwelling, whereas the cloakroom 224, second en-suite 223 and kitchen 225 may be on another floor of the dwelling. In such a situation, it may be convenient to have, as shown, two separate circuits, 230 and 231, to supply water to the various outlets. The two circuits 230 and 231 may each be fed from a different outlet, the temperature of the two outlets being separately adjustable, and each outlet lhaving its own associated temperature sensor 243. The temperature of the 2024296525 12 Mar 2026 water at the outlet (s) may be adjusted by mixing cold water with hot water from a source of fixed or variable temperature, or it may be adjusted by controlling the energy put into a heat source, such as an electric heating element or even a gas fired heater. Later we will describe hot water systems which include thermal energy storage arrangements, generally in 5 combination with a heat pump, and in such systems generally the hot water supply temperature may be adjusted by mixing in different proportions of cold water from a coldwater supply. Sometimes such systems may include an instantaneous heat source (such as an electrical heating element) downstream of the thermal energy storage arrangement, controlled by a processor of the system, and in such installations control of hot water supply 10 temperature may involve controlling the amount of energy supplied to the instantaneous water heater, as well possibly by mixing in different proportions of cold water from a coldwater supply. The master bathroom 221 is shown as including a shower outlet 235, a bath tap or faucet 236, and a tap 237 for a sink. The en-suite shower rooms 222 and 223 also include a 15 shower outlet 235, and a tap 237 for a sink. Conversely, the cloakroom 224 contains just a W.C. (not shown) and a hand basin with a tap 238. Finally, the kitchen 235 has a sink with a tap 239. A processor, or system controller, 240, with an associated memory 241, is coupled to the at least one flow measurement device 210 and the at least one flow regulator 215. It will 20 be appreciated that each of the two circuits 230 and 231 is provided with a respective flow measurement device 210 and flow regulator 215 The processor is also optionally connected to one or more temperature sensors 243, one for each of the circuits 230 and 231. This processor may be associated with an energy bank. The processor may also be coupled to an RF transceiver 242, which includes at least 25 one RF transmitter and at least one RF receiver, for bidirectional communication via Wi-Fi (RTM), Bluetooth (RTM), or the like, and preferably also to the Internet 244 for connection to a server or central station 245, and optionally to a cellular radio network (such as LTE, UMTS, 4G, 5G, etc.). By means of the RF transceiver 242 and / or the connection to the Internet, the processor 240 is able to communicate with a mobile device 250, which may for example be a 30 smart phone or tablet, for use by an installation engineer in configuring (and also optionally in mapping) the in-building water supply installation. The mobile device 250 includes software, such as a specific app, that co-operates with corresponding software in the system controller 240 and also potentially within server 245, to facilitate the configuring (and optionally mapping) methods according to embodiments of the invention, and in particular to synchronize actions taken by the engineer to a clock of the system controller 240 / server 245. The memory 241 contains code to enable the processor to perform a method of configuring (and optionally mapping) an in-building water supply installation processor, for example during a process of commissioning a new installation. During the commissioning process, in order to configure the hot-water supply installation 200, the engineer may be asked to setup a temperature sensor direct under a particular hot-water outlet, e.g., a specific tap or shower outlet, and to open the outlet fully at a specific moment. The system processor is configured to measure flow, the difference between both outflow and provided temperature, time delay and, preferably, outdoor temperature (data provided from an external temperature sensor). This will allow algorithms (e.g., MLAs) to calculate heat loss through the distribution system, distance between the outlet (tap or shower outlet) and the source of hot water, and finally, accurately adjust the outflow temperature to achieve the correct water temperature at the relevant controllable outlet (e.g., tap). For example, if the household includes children, then the maximum hot water temperature to every outlet other than, for example, the kitchen sink may be limited to 40C or 41C, whereas if there are infants in the house, the maximum temperature may be limited to 37C. Even in the absence of children, the maximum temperature for all outlets other than the kitchen sink may be set at 43C, and possibly 41C for shower outlets. The system may also be set up to restrict the flow of hot water to some classes of water outlets, such as handbasins and sinks, and possibly showers, with different maximum flow rates being set for each class of outlet, and / or maximum specific flow rates may be set for specific outlets - so lower flow rates set for bathrooms and cloakrooms used by children, for example. The determination of maximum temperatures and flow rates may be based on rules provided by the system supplier. Later we will discuss hot water supply systems which use heat pumps and thermal energy storage arrangements, and such systems benefit significantly from the imposition of temperature and flow rate control - since heat pumps sized according to the space heating need of a modestly sized 1 to 3-bedroom dwelling generally do not have the heating capacity to satisfy the instantaneous hot water demands of the household, without the provision of voluminous hot water storage tanks. By managing hot water flow and temperature, it may be possible to eliminate the need to provide hot water storage, while minimizing the size of the energy shortfall to be accommodated by other means. If the installation does include a thermal energy storage arrangement and a heat pump, the system supplier will typically pre-program the processor with suitable values for temperature and flow based on outlet type and household composition. A database of temperatures and optionally flow rates, based on outlet type and household composition may also be made available to the system controller over the internet, and updated from time to time. A user interface for the system controller may provide a means for occupiers and or service engineers to adjust the various settings according to changes in the household composition-for addition the arrival of guests with infants, children or elderly or infirm persons, of for example to allow users to set lower maximum temperatures and / or flow rates. Figure 3 shows, schematically, a heating system 300, showing some of the components that may be used in a system similar to that described above with reference to Figure 1 and flow paths between the components. As shown, heating system 300 includes a mains inlet of cold water 302 and a domestic hot water outlet 304, such as a tap or shower outlet and a domestic hot water heating appliance 310, such as a radiator. The system 300 further includes a heat pump 306, which may typically have a heating capacity of 3-12 kW, a heat exchanger 308, and a thermal storage appliance 342, such as a relatively small water tank holding approximately 15 litres of water. These components are connected by water flow pipes, with flow transducers, temperature transducers and valves that control the water flows though the pipes in a manner to be described below. The flow transducers and temperature transducers are all connected via signal lines to provide signals to a system controller 340, which controls the valves in order to control the system to operate in one of several operating modes as will be described below. One, some or all of the flow transducers may be replaced by pressure transducers that determine the pressure of the fluid in order to be able to determine the flow rate. Leading from the mains cold water inlet 302 a first flow path 312 leads to a first inlet HX1 of the heat exchanger 308. A temperature transducer TT01 and a flow transducer FT01 measure the temperature and the flow rate of the cold water at the mains cold water inlet 302. A temperature transducer TT02 and a flow transducer FT03 measure the temperature and the flow rate at the first inlet HX1 to the heat exchanger 308. A second flow path 314 leads from the first flow path 312 near the mains cold water inlet 302 towards the domestic hot water outlet 304. A first motorised valve MV01 is positioned in the second flow path 314 to regulate the water flow within the second flow path 314. A flow transducer FT02 measures the flow rate of the cold water passing through the first motorised valve MV01, from which it is selectively combined with water leaving a motorised three-way valve MV03 as will be further described below, towards the domestic hot water outlet 304 adjacent which a temperature transducer TT07 measures the temperature of the water leading to the domestic hot water outlet 304. A first part 316a of a third flow path 316 leads from the first flow path 312 nearer to the heat exchanger 308 than the second flow path 314. A second motorised valve MV02 is positioned in the first part 316a of the third flow path 316 to regulate the water flow within the first part 316a of the third flow path 316 leading to a lower part of the thermal storage appliance 342. A temperature transducer TT11 measures the temperature of the water at the lower part of the thermal storage appliance 342 and another temperature transducer TT10 measure the temperature of the water at an upper part of the thermal storage appliance 342. A second part 316b of the third flow path 316 leads from the upper part of the thermal storage appliance 342 to a second inlet B of a motorised three-way valve MV03, with a temperature transducer TT05 measuring the temperature of the water in the second part 315b of the third flow path 316. A return flow path 318 is provided to return water from an outlet of the motorised valve MV02 in the first part 316a of the third flow path 316 to an inlet of the motorised valve MV02 via a circulation pump 320 and a non-return valve 322. The heat exchanger 308 has a first outlet HX2 which is connecter to receive the water having entered the heat exchanger via first inlet HX1. A fourth flow path 324 leads from the first outlet HX2 of the heat exchanger to a first inlet A of the motorised three-way valve MV03, via an electric heater 326. A temperature transducer TT03 measures the temperature of the water leaving the first outlet HX2 of the heat exchanger 308 and a temperature transducer TT04 measures the temperature of the water leaving the electrical heater 326 and entering the first inlet A of the motorised three-way valve MV03. A fifth flow path 328 leads from the outlet AB of the motorised three-way valve MV03 towards the domestic hot water outlet 304, and combines with the first flow path 314 prior to reaching the domestic hot water outlet 304. A temperature transducer TT06 measures the temperature of the water leaving the outlet AB of the motorised three-way valve MV03 prior to being combined with water from the second flow path 314 and a temperature transducer TT07 measures the temperature of the water after it has been combined with water from the second flow path 314 as it enters the domestic hot water outlet 304. On the other side of the heat exchanger 308 from the first inlet HX1 and the first outlet HX2 are second inlet HX3 and second outlet HX4. The second inlet HX3 is fed by a sixth flow path 330 leading from an outlet of the heat pump 306 via a motorised three-way valve MV04, with a temperature of transducer TT08 measuring the temperature of the water at the second inlet HX3 of the heat exchanger 308. A seventh flow path 332 is coupled between the second outlet HX4 of the heat exchanger 308 and an inlet of the heat pump 306. As shown, the heat pump 306 includes a heat exchanger 334 and a circulating pump 336 to heat water received at the inlet and to output the heated water and the output. A temperature transducer TT09 measures the temperature of the water leaving the heat exchanger 308 and being passed into the inlet of the heat pump 306. Thus, the motorised three-way valve MV04 has a first inlet A coupled to the outlet of the heat pump 306, an outlet AB coupled to the second inlet HX3 of the heat exchanger 308. A second outlet B of the motorised three-way valve MV04 leads to an inlet of the domestic hot water heating appliance 310, whose outlet leads to the seventh flow path 332. A dotted line labelled 344 illustrates all the components of the system that can be included in a housing that may be made of a similar size and shape as to replace a combination boiler, although it will be appreciated by people skilled in the art that in some circumstances, the components may be otherwise arranged, inside or outside such a housing, which may not be needed at all in some circumstances. In particular, for example temperature transducer TT09 may be located within the housing 344 nearer the heat exchanger 308 or outside the housing 344 nearer the domestic hot water heating appliance 310. Others of the temperature and flow transducers, such as, for example, flow transducer FT01 and / or temperature transducer TT01 may similarly be positioned inside or outside the housing, as desired. Modes of operation of the heating system 300 will now be more fully described with reference to Figures 4 to 12, which show the system of Figure 3, but, for clarity, without the signal lines between the controller 340 and the various flow transducers and temperature transducers nor the apparatus. Instead, the flow paths used in the particular mode of operation are shown with overlayed dotted lines to illustrate which flow paths and components are being controlled in that mode. There are a number of differing operating modes, each of which will be described in turn, although several may be interrelated and used in combination or separately. The modes are: Mode 1 (Figure 4): Heat Exchanger Charging Mode in which the heat exchanger 308 is used to heat water that is used to fill (or charge) the thermal storage appliance 342; Mode 2 (Figure 5): Electric Heater Charging Mode in which the electric heater 326 is used to heat water that is used to charge the thermal storage appliance 342; Mode 3 (Figure 6): Initial Hot Water Mode, in which hot water provided to the domestic hot water outlet 304 is provided either by the thermal energy storage appliance 342, if it is charged with hot water, or is heated by the electric heater 326, or a combination of both, as required; Mode 4 (Figure 7): Mixed Water Mode to decrease temperature of water from Mode 3 is mixed with cold water from the mains cold water inlet 302 to reduce the temperature of the water being provided to the domestic hot water outlet 304; Mode 5 (Figure 8): Steady State Mode in which the heat pump 306 is used to heat water from the cold water from the mains cold water inlet 302 at the heat exchanger and to provide the heated water, optionally further heated by the electric heater 326, and mixed with cold water from the mains cold water inlet 302 to reduce the temperature of the water being provided to the domestic hot water outlet 304; Mode 6 (Figure 9): Combined Mode, which is a combination of Modes 3 and 5; Mode 7 (Figure 10): Heat Pump Defrost Mode; Mode 8 (Figure 11): House Heating Mode; and Mode 9 (Figure 12): Overall Mode, which is a combination of Modes 6 and 8. Turning, firstly, to Figure 4, there is illustrated a first mode of operation (the "Heat Pump Charging of Thermal Storage Mode") in which the thermal storage appliance 342 is charged with hot water provided from the heat exchanger 308. In this first mode of operation, the second motorised valve MV02 is closed and the circulation pump 320 in the return flow path 318 is turned on so that water is pumped from the thermal storage appliance 342 via the circulation pump 320, the non-return valve 322 and the first flow path 312 to the first inlet HX1 of the heat exchanger 308. Since the water is being pumped from the first part 316a of the third flow path 316 into the first flow path 312, water from the domestic cold water inlet 302 does not affect the flow. The water is heated in the heat exchanger 308 and is passed from the first outlet HX2 through fourth flow path 324 via the electric heater 326, which in this mode is turned off, to the motorised valve MV03 which is controlled to direct the water from port A to port B, so that the water returns to the thermal storage appliance 342. It will be apparent that the water can be so looped around more than once, if desired, until the water at the thermal storage appliance 342 reaches a predetermined temperature, as measured by temperature transducer TT10 or temperature transducer TT04. In order to provide the heat exchanger 308 with hot water from the heat pump, the motorized valve MV04 is controlled so that water in the sixth flow path 330 from the heat pump 306 passes through port A to port AB of the motorized valve MV04 and hence to the second inlet HX3 of the heat exchanger 308. The water then returns from second outlet HX4 of the heat exchanger 308 to the heat pump 306. In this first mode the heat pump power is modulated to transfer heat to the circulating hot water loop, charging the thermal energy storage appliance 342, for example a 15 litre tank, with continued operation of the circulation pump 320 on the hot water side. An example case would be if the circulation pump 320 runs at 6L / min, and the heat pump 306 is modulated to heat the water in the hot water loop to 55°C at the heat exchanger 308, the circulation pump 320 would run for approximately 6 minutes to charge the water in the thermal energy storage appliance 342 to 55°C in 2 passes through the loop. Figure 5 illustrates a second mode of operation (the "Electric Heater Charging of Thermal Storage Mode") in which the thermal storage appliance 342 is charged with hot water heated by the electric heater 326. In this mode, similarly to the first mode, the second motorised valve MV02 is closed and the circulation pump 320 in the return flow path 318 is turned on so that water is pumped from the thermal storage appliance via the circulation pump 320, the non-return valve 322 and the first flow path 312 to the first inlet HX1 of the heat exchanger 308. The heat pump does not provide thermal energy to the heat exchanger in this mode, so the water is passed from the first outlet HX2 of the heat exchanger through fourth flow path 324 to the electric heater 326, which in this mode is actively controlled to heat the water. The hot water is then passed to the motorised valve MV03 which is controlled to direct the water from port A to port B, so that the hot water returns to the thermal storage appliance 342. It will be apparent that the water can be so looped around more than once, if desired, until the water at the thermal storage appliance 342 reaches a predetermined temperature, as measured by temperature transducer TT10 or temperature transducer TT04. In this second mode the electric heater power is modulated to heat the circulating water on the hot water side to the desired temperature. An example case would be if the circulation pump 320 runs at 5L / min, and the electric heater 326 is modulated to heat the water in the hot water loop to 55°C as measured at temperature transducer TT04, the circulation pump 320 would run for 6 minutes to charge the water in the thermal energy storage appliance 342 to 55°C in 2 passes. The controller can therefore select whether to use the first mode or the second mode to charge the thermal energy storage appliance. This may depend on whether the heat pump is available and active. If it is active and hot fluid is already available at the heat exchanger then the first mode can be selected. If the heat pump is already active but motorised valve MV04 is not allowing the hot fluid to pass thorough to the heat exchanger, then the first mode may still be selected and the motorised valve MV04 is controlled, as mentioned above, so that the hot fluid passes from port A to port AB and hence to the second inlet HX3 of the heat exchanger. On the other hand, if the heat pump is not active, and given that, as described above, it takes some time for it to start to produce hot fluid, then the controller may select the second mode, so as to use the electric heater to heat the water to charge the thermal energy storage appliance. In the third mode of operation (the "Initial Hot Water Mode"), shown in Figure 6 hot water is provided to the domestic hot water outlet 304 either by the thermal energy storage appliance 342, if it is charged with hot water, or is heated by the electric heater 326, or a combination of both. If the thermal energy storage appliance 342 is charged full of hot water, then that can be used in preference to using the electric heater 326 to heat the water. To use hot water from the thermal energy storage appliance 342, the motorised valve is MV02 is open, so that the third flow path 316 is used to take cold water from the mains cold water inlet 302 to displace hot water from the thermal storage appliance 342. The hot water from the thermal storage appliance 342 passes through motorised valve MV03 from port B to port AB. As the temperature of the water from the thermal energy storage appliance 342 reduces (due to mixing with the cold water from the mains cold water inlet 302), the motorised valve MV03 is controlled to gradually open the pathway from port A to port AB, while gradually closing the pathway from port B to port AB. The flow rates across ports A-AB and ports B-AB are configured to be inversely proportional so that the flow of water out from port AB into the fifth flow path 328 leading to the domestic hot water outlet 304 remains constant. This is regulated according to the temperature sensed at temperature transducer TT06 depending on whether the sensed temperature is less than a desired temperature at temperature transducer TT06. Thus, if the temperature at temperature transducer TT06 is less than the desired temperature, the proportion of valve port B allowing fluid flow to port AB can be reduced from 100% to allow flow through port A, whilst reducing flow from port B. The now reduced flow from port B is therefore mixed with coming from port A. The water passing through port A of motorised valve MV03 comes from the fourth flow path 324 and via the electric heater 326 where it is heated, as necessary, to provide the hot water at port AB at the desired temperature, as sensed at temperature transducer TT06. Water in the fourth flow path 324 comes through the heat exchanger 308, having reached it via the first flow path 312 from the mains cold water inlet 302. This mode of operation relies on the thermal energy storage appliance 342 being pre-charged, for example by either of the first or second modes of operation. Typically, the water in the thermal energy storage appliance 342 is charged to 1.25 times the desired temperature as sensed at temperature transducer TT07 measured as temperatures at temperature transducers TT11 and TT10. When there is a secondary hot water demand of flow, as measured at flow transducer FT01, water flows through the third flow path 316 and into the thermal energy storage appliance 342. The thermal energy storage appliance 342 may be a stratified tank holding 15L, where 15L of water entering at a temperature measured by temperature transducer TT01, will displace 15L of preheated water. The depletion of the tank is measured by the read temperature at temperature transducers TT10 and TT11, and by knowing amount of water that has passed through the tank: V=t*(Q@ FT01-Q@ FT03-Q@ FT02) Where V is the depletion of the tank; t is time; Q@FT01 is the flow measured at flow transducer FT01; Q@FT02 is the flow measured at flow transducer FT02; and Q@FT03 is the flow measured at flow transducer FT03. As the water flows out of the tank and into port B of motorised valve MV03, if for whatever reason the temperature at temperature transducer TT05 is less than the desired temperature at temperature transducer TT07, the electric heater 326 can be used to top up the temperature of the water passing through the fourth flow path 324, where motorised valve MV03 is controlled to at least partially open port A to allow a at least a proportion of the flow measured at flow transducer FT01 through the fourth flow path 324 to the electric heater 326, where the bypassed proportion of flow of at flow transducer FT03 can be heated from the temperature at temperature transducer TT03 to a temperature at temperature transducer TT04 by controlling the electric heater 326. This is a useful mode to use when the heat pump 306 is not operational, or not yet fully operational, when it is not providing hot fluid to the heat exchanger 308. Of course, as the heat pump heats up, the fluid will start to get hotter, and may be provided to the heat exchanger 308, so that the water passing through it may start to increase in temperature, as measured by temperature transducer TT03, so that the heating provided by the electric heater 326 may be controlled to produce the appropriate desired temperature. Figure 7 shows the fourth mode of operation, which is the Mixed Water Mode in which the temperature of the hot water from the thermal energy storage appliance 342 and / or from the electric heater 326 (provided as per the third mode of operation described above) or from the heat exchanger 308 if that is producing hot water as per the fifth mode, is mixed with cold water from the mains cold water inlet 302 to reduce the temperature of the water being provided to the domestic hot water outlet 304. In this mode, whether the hot water leaving the port AB of the motorised three-way valve MV03 is provided via the heat exchanger 308 via the fourth flow path 324 (whether or not that water is heated by the electrical heater 326) or from the thermal storage appliance 342, the temperature of the hot water leaving the port AB of the motorised three-way valve MV03 is measured using the temperature transducer TT06. The temperature is signalled to the system controller 340 (not shown in Figures 4 to 12). The controller 340 then determines whether the temperature at temperature transducer TT06 is higher than the desired temperature for the hot water to be available at the domestic hot water outlet 304. If it is higher, then cold water from the second flow path 314 is mixed into the hot water leaving the port AB of the motorised three-way valve MV03 into the fifth flow path 328 by opening the motorised valve MV01 to allow cold water from the mains cold water inlet 302 to flow through the second flow path 314 to the fifth flow path 328. The amount by which the motorised valve MV01 is opened will depend on the temperature of the cold water from the mains inlet 302 as measured by the temperature transducer TT01 and the flow rate of the cold water from the mains inlet 302 as measured by the flow transducer FT01 to produce the desired flow rate as measure by flow transducer FT02 in the second flow path 314 leading to the fifth flow path 328 so that the cold water from the second flow path 314 mixes with the hot water in the fifth flow path 328 to produce the desired temperature for the water to be available at the domestic hot water outlet 304, as measured by the temperature transducer TT07. A suitable control program executed by the controller will modulate this mixing in normal operation, preventing any overshoot from the desired temperature at the domestic hot water outlet 304. This firstly acts as a safety feature to prevent scalding of a user who doesn't have temperature safety valves installed on taps or faucets in the home. Secondly, the mixing allows the thermal storage appliance 342 to be charged to a higher temperature than that of the desired outlet temperature, so that when the system is run in a mode of operation where the thermal storage appliance 342 provides the hot water to be used from the domestic hot water outlet 304, the higher temperature water is mixed down with cold water from the mains cold water inlet, thereby producing a slower drain on the thermal storage appliance 342 and giving it a proportionally higher effective volume. After the third mode of operation, in which the hot water is initially provided by the thermal energy storage appliance 342 of from the electric heater 326 (or a combination of both), once the heat pump has reached full operation and is providing hot fluid to the heat exchanger 308, the fifth mode of operation may be instituted. In this Steady State Mode, as illustrated in Figure 8, the motorised valve MV02 is shut so that there is no flow through the third flow path 316 and the thermal energy storage appliance 342. The electric heater 326 is active and controllable by the controller. The mixing control as described above with reference to the fourth mode is also active. Thus, motorised valve MV04 is controlled to pass water from port A to port AB. In this mode the heat pump 306 is actively providing heated fluid via the sixth flow path 330 and the motorised valve MV04 set to pass the fluid from port A to port AB to the heat exchanger 308 at a temperature determined by the measured flow rate of secondary hot water demand and set hot water temperature as measured a temperature transducer TT07. The water flow passing through the heat exchanger 308 is heated by the heat exchanger to a temperature measured by temperature transducer TT03. Thus, the flow measured at flow transducer FT03, the temperature measured by temperature transducerTT02, and the temperature measured by temperature transducer TT03 can be used to determine the amount of energy provided by the heat pump and subsequently provide feedback to the heat pump for power output adjustments. If the temperature measured by temperature transducer TT03 is determined to be less than the desired temperature at temperature transducer TT07, the electric heater 326 is controlled to heat the water to top the temperature of the water to the required temperature as measured at the temperature transducer TT04. It will be apparent that since the water is passing through the motorised valve MV03 from port A to port AB, the temperature measured by temperature transducer TT04 will be the same as the temperature at temperature transducer TT06. If the temperature measured by temperature transducer TT06 is greater than desired temperature at temperature transducer TT07, cold water can be mixed with the hot water described for the fourth mode of operation, in which the temperature of the hot water is mixed with cold water from the mains cold water inlet 302 to reduce the temperature of the water being provided to the domestic hot water outlet 304. Figure 9 shows the sixth mode of operation, which is, essentially, a combination of the third (Initial Hot Water) and fifth (Steady State) modes. The hot water is provided from the heat exchanger 308 or from the thermal storage appliance 342. The electric heater 326 can be used to top up the water temperature from the heat exchanger 308, if the water temperature measured at temperature transducer TT06 is lower than the desired water temperature at temperature transducer TT07. On the other hand, if the water temperature measured at temperature transducer TT06 is higher than the desired water temperature at temperature transducer TT07 cold water from the mains cold water inlet 302 via the second flow path 314 can be mixed into the hot water to reduce its temperature to the desired temperature. There are occasions, in inclement weather, when the heat pump is at risk of freezing up. In such circumstances, whether to defrost a frozen heat pump, or to try to prevent the heat pump freezing if it is known that the temperature is likely to fall to below freezing, the controller may control the system to bring the seventh mode (the "Heat Pump Defrost Mode") into operation. In this seventh mode of operation, as shown in Figure 10, the second motorised valve MV02 is closed and the circulation pump 320 in the return flow path 318 is turned on so that water is pumped from the thermal storage appliance 342 via the circulation pump 320, the non-return valve 322 and the first flow path 312 to the first inlet HX1 of the heat exchanger 308. Since the water is being pumped from the first part 316a of the third flow path 316 into the first flow path 312, water from the domestic cold water inlet 302 does not affect the flow. The water is passed from the first outlet HX2 through fourth flow path 324 via the electric heater 326 to the motorised valve MV03 which is controlled to direct the water from port A to port B, so that the water returns to the thermal storage appliance 342 and may circulate around again. The water entering at the first inlet HX1 of the heat exchanger 308 is controlled to be hot, either from the thermal storage apparatus, or, more likely, from being heated by the electric heater 326, or a combination of both, depending on the extent to which the thermal storage medium is charged with hot water. In this seventh mode the electric heater is active and is modulated to transfer heat to the circulating hot water loop, passing through the thermal energy storage appliance 342. The motorized valve MV04 is controlled so that water in the sixth flow path 330 from the heat pump 306 passes through port A to port AB of the motorized valve MV04 and hence to the second inlet HX3 of the heat exchanger 308. The water then returns from second outlet HX4 of the heat exchanger 308 to the heat pump 306. As the water passes from the second inlet HX3 to second outlet HX4 of the heat exchanger 308 it is heated by heat exchange with the hot water entering through the first inlet HX1 of the heat exchanger 308 to the first outlet HX1, as described above. The heated water returned to the heat pump 306 is then able to provide thermal energy to the refrigerant loop at the heat pump 306, which in turn is being circulated via the heat pump's compressor. The now hot refrigerant is then able to defrost the evaporator coils. The eighth mode (the "House Heating Mode") illustrated in Figure 11 assumes that no hot water is required at the domestic hot water outlet 304 (or any other hot water outlet, and this mode is therefore focussed exclusively on providing hot fluid, which may be water, for heating the domestic dwelling or other building, either through the use of radiators or a hot water underfloor heating system. In this mode, the heat pump is actively producing hot water which is directed through the motorised valve MV04 controlled to pass the hot water from port A to port B so that the hot water passes to the domestic hot water heating appliance 310, whose outlet leads back to the heat pump 306. Figure 12 illustrates the ninth mode, which is a combination of the sixth and eighth modes, which is, therefore, a combination of the third (Initial Hot Water), fifth (Steady State) and eighth (House Heating) modes so that all the various modes discussed above can be combined, as required. In this mode, the electric heater 326 is active and modulable and all four motorised valves MV01, MV02, MV03 and MV04 are active and modulable. In this mode the Heat Pump 306 can provide both heating (as per the eighth mode discussed above) and thermal energy to heat or preheat hot water at the heat exchanger 308. As described above in relation to the sixth mode, the hot water is provided from the heat exchanger 308 or from the thermal storage appliance 342. The electric heater 326 can be used to top up the water temperature from the heat exchanger 308, if the water temperature measured at temperature transducer TT06 is lower than the desired water temperature at temperature transducer TT07. On the other hand, if the water temperature measured at temperature transducer TT06 is higher than the desired water temperature at temperature transducer TT07 cold water from the mains cold water inlet 302 via the second flow path 314 can be mixed into the hot water to reduce its temperature to the desired temperature. As mentioned above, most of the components of the system, excluding the heat pump 306, the domestic hot water outlet 304 and the domestic hot water heating appliance 310 are generally included within an enclosure (or housing) 344 that may be made of a similar size and shape as to replace a combination boiler. The enclosure 344 may include insulating material to mitigate against heat loss and it will be apparent that the differing operating modes, may be used in combination or separately, as desired and controlled by the controller.
Claims
1. A domestic hot water provisioning system comprising:a cold water inlet for receiving cold water from a mains supply;a hot water outlet for providing hot water on demand to a domestic hot water outlet activated by a user and connected to the cold water inlet;a heat exchanger having a first inlet connected to the cold water inlet and a first outlet connected to the hot water outlet, the heat exchanger selectively heating water between the first inlet and the first outlet using a hot fluid selectively received from a hot fluid source;an electric heater for selectively heating water;a thermal storage appliance for storing heat connected to the hot water outlet;a circulation pump for pumping water from the thermal storage appliance to the heat exchanger;a first flow path between the cold water inlet and the first inlet of the heat exchanger;a second flow path between the cold water inlet and a fifth flow path;a third flow path having a first part between the thermal storage appliance and the first flow path and a second part between the thermal storage appliance and the fifth flow path, wherein the circulation pump is located in a return flow path in parallel with the first part of the third flow path;a fourth flow path including the electric heater in series between the first outlet of the heat exchanger and the fifth flow path;the fifth flow path from the fourth flow path and the third flow path to the hot water outlet; anda controller coupled to at least the electric heater and the circulation pump for controlling operation of the hot water provisioning system in one or more operating modes including:a charging mode for charging the thermal storage appliance by controlling the system to heat the thermal storage appliance, wherein the thermal storage appliance is heated to a temperature based on availability of heat to the heat exchanger, wherein the thermal storage appliance may provide hot water via the third flow path to the fifth flow path to the hot water outlet; anda mixed water mode for providing hot water to the hot water outlet, the mixed water mode comprising:2024296525 12 Mar 2026a) determining whether hot water is being demanded at the hot water outlet, and, if hot water is being demanded at the hot water outlet, controlling the system to pass hot water from the thermal storage appliance or from the electric heater or from the heat exchanger or from a combination thereof via the fifth flow path to the hot water outlet;b) determining a temperature of the hot water at the hot water outlet;c) if the hot water at the hot water outlet is determined to be hotter than a desired temperature, controlling the system to pass cold water from the cold water inlet via the second flow path, to mix with the hot water from the fourth flow path to reduce the temperature of the mixed water passed via the fifth flow path to the hot water outlet; andd) repeating steps b) and c) to control the flow of cold water though the second flow path so that the temperature of the mixed water available at the hot water outlet is at or lower than the desired temperature.
2. A hot water provisioning system according to claim 1, further comprising one or moretemperature sensors located at or adjacent the hot water outlet and coupled to transmit temperature signals to the controller to enable the controller to determine the temperature of the hot water at the hot water outlet in step b).
3. A hot water provisioning system according to either claim 1 or claim 2, furthercomprising one or more flow transducers in or adjacent a flow path to the hot water outlet coupled to transmit flow signals to the controller to enable the controller to determine whether hot water is being demanded at the domestic hot water outlet.
4. A hot water provisioning system according to either claim 1 or claim 2, furthercomprising one or more pressure transducers in or adjacent a flow path to the hot water outlet coupled to transmit pressure signals to the controller to enable the controller to determine whether hot water is being demanded at the domestic hot water outlet.
5. A hot water provisioning system according to any preceding claim, wherein the coldwater inlet, the hot water outlet, the controller, the heat exchanger, the electric heater, the thermal storage appliance, and the circulation pump are contained within a housing.2024296525 12 Mar 20266. A hot water provisioning system according to claim 5, wherein the housing hasmaximum dimensions of 90cm in height, 60cm in width and 60cm in depth.
7. A hot water provisioning system according to claim 6, wherein the housing hasdimensions of about 75cm in height, about 45cm in width and about 50cm in depth.
8. A method of controlling a domestic hot water provisioning system, the domestic hotwater provisioning system comprising:a cold water inlet for receiving cold water from a mains supply;a hot water outlet for providing hot water on demand to a domestic hot water outlet activated by a user and connected to the cold water inlet;a heat exchanger having a first inlet connected to the cold water inlet and a first outlet connected to the hot water outlet, the heat exchanger selectively heating water between the first inlet and the first outlet using a hot fluid selectively received from a hot fluid source;an electric heater for selectively heating water;a thermal storage appliance for storing heat connected to the hot water outlet;a circulation pump for pumping water from the thermal storage appliance to the heat exchanger;a first flow path between the cold water inlet and the first inlet of the heat exchanger;a second flow path between the cold water inlet and a fifth flow path;a third flow path having a first part between the thermal storage appliance and the first flow path and a second part between the thermal storage appliance and the fifth flow path, wherein the circulation pump is located in a return flow path in parallel with the first part of the third flow path;a fourth flow path including the electric heater in series between the first outlet of the heat exchanger and the fifth flow path;the fifth flow path from the fourth flow path and the third flow path to the hot water outlet; anda controller coupled to at least the electric heater and the circulation pump;the method comprising the controller controlling operation of the hot water provisioning system in one or more operating modes including:a charging mode for charging the thermal storage appliance by controlling the system to heat the thermal storage appliance, wherein the thermal storage appliance is heated to a temperature based on availability of heat to the heat exchanger,2024296525 12 Mar 2026wherein the thermal storage appliance may provide hot water to the hot water outlet via the third flow path to the fifth flow path to the hot water outlet; anda mixed water mode for providing hot water to the hot water outlet, the mixed water mode comprising:a) determining whether hot water is being demanded at the hot water outlet, and, if hot water is being demanded at the hot water outlet, controlling the system to pass hot water from the thermal storage appliance or from the electric heater or from the heat exchanger or from a combination thereof via the fifth flow path to the hot water outlet;b) determining a temperature of the hot water at the hot water outlet;c) if the hot water at the hot water outlet is determined to be hotter than a desired temperature, controlling the system to pass cold water from the cold water inlet via the second flow path, to mix with the hot water from the fourth flow path to reduce the temperature of the mixed water passed via the fifth flow path to the hot water outlet; andd) repeating steps b) and c) to control the flow of cold water though the second flow path so that the temperature of the mixed water available at the hot water outlet is at or lower than the desired temperature.
9. A method of controlling a domestic hot water provisioning system according to claim8, wherein determining the temperature of the hot water at the hot water outlet in step b) comprises using one or more temperature sensors located in or adjacent the hot water outlet and transmitting the temperature signals from the one or more temperature sensors to the controller10. A method of controlling a domestic hot water provisioning system according to eitherclaim 8 or claim 9 wherein determining whether hot water is being demanded at the domestic hot water outlet comprises using one or more flow transducers in or adjacent a flow path to the hot water outlet and transmitting the flow signals from the one or more flow transducers to the controller.
11. A method of controlling a domestic hot water provisioning system according to either claim 8 or claim 9, wherein determining whether hot water is being demanded at the domestic hot water outlet comprises using one or more pressure transducers in or adjacent a flow path2024296525 12 Mar 2026to the hot water outlet and transmitting the pressure signals from the one or more pressure transducers to the controller.
12. A computer readable medium having instructions stored thereon, which, when executed by one or more processors of a controller, cause the controller to perform the method of any one of claims 8 to 11.