Patent Description:
Indoor heating can be provided through a sealed central heating system, which comprises a water heater that supplies heated water to a plurality of radiating heaters fluidly connected by a plurality of pipes in a closed heating circuit. Such a sealed central heating system generally comprises, amongst other things, a pump for urging water around the heating circuit, a pressure gauge for measuring the water pressure within the heating circuit, and a filling circuit between the cold water main and a return pipe (through which water is returned from the radiating heaters to the water heater) for filling the heating circuit with cold mains water so as to increase the pressure within the heating circuit.

A sealed central heating system should operate at a predetermined range of operating pressure, and when the water pressure within the heating circuit falls below the predetermined range of operating pressure, the filling circuit is used so as to repressurise the heating circuit to the desired operating pressure. Since the central heating circuit is pressurised, to protect incoming mains water from being contaminated by a backflow from the central heating system, the filling circuit is commonly provided with an isolation valve downstream for stopping water from the heating circuit from entering the filling circuit as well as a flow control valve upstream for releasing mains water into the filling circuit.

There can be different reasons for the pressure in the heating circuit to fall, for example air being trapped in the closed heating circuit, a leak in one or more valves in the radiating heaters, a fault in one or more pipes in the heating circuit, or a fault or leak in the water heating system that heats the water of the heating circuit. If the fault or leak is in the water heating system and the heating circuit is repressurised without the fault or leak being remedied, the drop in pressure in the water heating system as a result of the fault or leak may lead to water from the heating circuit back-feeding into the water heating system, potentially causing a contamination of the mains water supply directed to other water outlets such as taps and shower.

Conventionally, to identify the cause for pressure loss, a skilled engineer would first inspect for leaks on valves and pipes around the heating circuit, and if a leak cannot be found, a test on the water heating system is performed by pressuring the system to the predetermined operating pressure then engaging the isolation valve to the heating circuit to determine whether the water heating system maintains the operating pressure. During testing of the water heating system, the water heating system is prevented from operation. If the water heating system fail to maintain the operating pressure for a sufficient length of time (e.g. a day), then the fault is deemed to lie within the water heating system.

Such manual inspections and tests are time consuming and prone to error. For example, a leak in a valve or pipe of the heating circuit may be missed during manual inspections, and the engineer is required to balance between disrupting the normal operation of the water heating system and allowing a long enough time to determine whether the water heating system is able to maintain the operating pressure, so the engineer may be required to attend the water heating system over a long period of time or a fault in the water heating system may be missed.

<CIT> discloses an arrangement for detecting and locating a leak in a water pipe system, with a water treatment, with a pump, with a supply line and a discharge line, with at least one on the supply line and the circulation line connected to the discharge line, with at least one inlet valve, at least one outlet valve and at least one pressure sensor in at least one circulation line and / or the supply line and the discharge line, the inlet valve and the outlet valve electrically controllable, with control means for controlling the input valves and the output valves, with detection means for recording the time course the measured values (P) of the at least one pressure sensor, with evaluation means for evaluating the time course of the pressure change (dP/dt) and for comparing the amount of the pressure change (dP/dt) with one Limit value and with output means for outputting a display signal indicating a leak if the amount of pressure change (dP/dt) exceeds the limit value. <CIT> discloses a hydronic heating system that monitors pressure in the system, where certain pressures or variations of pressures may indicate one or more conditions in the system which may be good or adverse. <CIT> discloses a method for detecting a leak due to loss of a medium in an at least temporarily closable line network. A flow (V) or pressure (P) of the medium in the line network is measured. It is recognized that there is no leak if there are standstill phases (S) in which no flow (V) or pressure change (ΔP) was measured. <CIT> discloses an apparatus for monitoring a fluid conduit system for leaks. After closing a main valve that fluidly connects a fluid source to the conduit system, the time is measured for the pressure in the conduit system to drop to a predetermined first value. Upon reaching the first value a shunt valve is opened and the time is measured for the pressure to rise to a second predetermined value. The leakage flow is calculated from the two measured times and the two pressures together with known constants for the control system.

It is therefore desirable to provide improved methods and systems for determining a leakage in a water heating system to prevent a backflow from a sealed heating circuit.

The invention is defined in the independent claims, with optional features being defined in the dependent claims. An aspect of the present technology provides a computer-implemented method of determining a leak in a water heating system, the water heating system comprising a control module configured to control operation of the water heating system, at least one water heating module configured to heat water to be circulated around a sealed heating circuit, a first valve configured to control water flow returning from the heating circuit to the water heating system and a second valve configured to control water flow from the water heating system to the heating circuit, the method being performed by the control module and comprising: receiving first sensor data from a first pressure sensor disposed upstream of the first valve; receiving second sensor data from a second pressure sensor disposed downstream of the first valve; upon determining that the first sensor data and/or the second sensor data indicates a water pressure below a reference water pressure, closing the first valve and the second valve to isolate the heating circuit and the first pressure sensor from the water heating system and the second pressure sensor; monitoring the first sensor data indicating a water pressure in the heating circuit and the second sensor data indicating a water pressure in the water heating system; and upon determining that the second sensor data indicates a fall in water pressure, determining a leak in the water heating system, wherein the water heating system comprises a third valve configured to control a flow of mains water into the heating circuit, the method further comprising, upon determining that the water pressure indicated by the first sensor data and the water pressure indicated by the second sensor data remain substantially constant, releasing the first valve and the third valve to allow mains water into the heating circuit to increase the water pressure to at least the reference water pressure.

According to the invention, it is possible to determine whether there is a leak or a fault in the water heating system when the water pressure in the heating circuit falls below the reference water pressure (or a minimum water pressure). In doing so, it is possible to give an early warning when a leak occurs to prevent more serious issues caused by a delay in detection. Moreover, if there is a leak or fault in the water heating system and the heating circuit is repressurised without the leak or fault being repaired, it can lead to a backflow from the heating circuit into the mains water feeding loop, contaminating water supply with bacteria harmful to health. Thanks to the invention, it is possible to prevent backflow by determining whether there is a leak in the water heating system before the heating circuit is repressurised.

A further aspect of the present technology provides a computer-readable medium comprising machine-readable code which, when executed by a processor, causes the processor to perform the methods described above.

A yet further aspect of the present technology provides a water heating system comprising: at least one water heating module configured to heat water to be circulated around a sealed heating circuit; a first valve configured to control water flow returning from the heating circuit to the water heating system; a second valve configured to control water flow from the water heating system to the heating circuit; a first pressure sensor configured to measure a water pressure in the heating circuit disposed upstream of the first valve; a second pressure sensor configured to measure a water pressure in the heating circuit disposed downstream of the first valve; and a control module configured to control operation of the water heating system, the control module comprising: at least one processor; and a non-transitory computer-readable medium having stored thereon software instructions that, when executed by the at least one processor, cause the control module to: receive first sensor data from the first pressure sensor; receive second sensor data from the second pressure sensor; upon determining that the first sensor data and/or the second sensor data indicates a water pressure below a reference water pressure, closing the first valve and the second valve to isolate the heating circuit and the first pressure sensor from the water heating system and the second pressure sensor; monitoring the first sensor data indicating a water pressure in the heating circuit and the second sensor data indicating a water pressure in the water heating system; and upon determining that the second sensor data indicates a fall in water pressure, determining a leak in the water heating system, further comprising a third valve configured to control a flow of mains water into the heating circuit, wherein the software instructions further cause the control module to, upon determining that the water pressure indicated by the first sensor data and the water pressure indicated by the second sensor data remain substantially constant, releasing the first valve and the third valve to allow mains water into the heating circuit to increase the water pressure to at least the reference water pressure.

Additional aspects and advantages of implementations of the present technology will become apparent from the following description, the accompanying drawings and the appended claims.

In view of the foregoing, the present disclosure provides various approaches for determining a leak in a water heating system.

In embodiments of the present techniques, a centralized water provision/heating system provides cold and heated water to a plurality of water outlets, including taps, showers, etc. and heated water to be circulated around a sealed heating circuit to provide central heating in a building in a domestic or industrial/commercial setting. An exemplary water provision system according to an embodiment is shown in <FIG>.

In the present embodiment, the water heating system <NUM> comprises a control module <NUM>. The control module <NUM> is communicatively coupled to, and configured to control, various elements of the water heating system, including a flow control <NUM> for example in the form of one or more valves arranged to control the flow of water into, out of and around the system, a (ground source or air source) heat pump <NUM> configured to extract heat from the surroundings and deposit the extracted heat in a thermal energy storage <NUM> to be used to heat water, and one or more electric heating elements <NUM> configured to directly heat cold water to a desired temperature by controlling (by the control module <NUM>) the amount of energy supplied to the electric heating elements <NUM>. Heated water, whether heated by the thermal energy storage <NUM> or heated by the electric heating elements <NUM>, is then directed to one or more water outlets as and when needed. In the embodiments, the heat pump <NUM> extracts heat from the surroundings into a thermal energy storage medium within the thermal energy storage <NUM>. The thermal energy storage medium may optionally also be heated by other sources such as the electric heating elements <NUM> if desired. The heat pump <NUM> continues to deposit extracted heat to the thermal energy storage medium until it reaches a desired operation temperature, then cold water e.g. from the mains can be heated by the thermal energy storage medium in a heat exchanger <NUM> to the desired temperature. The heated water may then be output for distribution around a water distribution network that comprises e.g. various hot/cold water taps, shower(s), etc..

In the present embodiment, the control module <NUM> comprises one or more processors <NUM> configured to execute instructions for controlling operations of the water heating system. In particular, the control module <NUM> is configured to receive sensor data from a plurality of sensors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. The plurality of sensors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-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, and may include other sensors not directly linked to the water provision system <NUM> such as one or more motion sensors, 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 one or more processors <NUM> of the control module <NUM> 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 <NUM> to the thermal energy storage <NUM> or to the electric heating elements <NUM> to be heated.

In the present embodiment, a pressure sensor <NUM>-<NUM> is disposed at a position in the water heating system <NUM> to measure the water pressure of heated water output by the water heating system <NUM>, and sensor data indicating the measured water pressure is received by the control module <NUM> which processes the sensor data and controls operation of the water heating system based on the results. A flow control e.g. valve <NUM>-<NUM> is disposed at a position in the water heating system <NUM> to control the flow of heated water output by the water heating system <NUM> to the water distribution network. The control module <NUM> is configured to control the operation of the valve <NUM>-<NUM> based on the received sensor data from the pressure sensor <NUM>-<NUM>.

Embodiments of the present technology make use of a heat pump and a thermal energy storage (or heat reservoir) as a source of heat for heating cold 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. Moreover, in some embodiments, the heat pump <NUM> may for example use a phase change material (PCM), which changes from a solid to a liquid upon heating, as a thermal energy storage medium. Additional time may therefore be required to for the heat pump to first transferred a sufficient amount of heat to turn the PCM from solid to liquid, if it has been allowed to solidify, before it can further raise the temperature of the liquified thermal storage medium. Although this approach of heating water is slower, it consumes less energy to heat water compared to electric heating elements, so overall, energy is conserved and the cost for providing heated water is reduced.

In the present embodiments, a phase change material may be used as a thermal storage medium for the heat pump. One suitable class of phase change materials are paraffin waxes which have a solid-liquid phase change at temperatures of interest for domestic hot water supplies and for use in combination with heat pumps. Of particular interest are paraffin waxes that melt at temperatures in the range <NUM> to <NUM> degrees Celsius (°C), and within this range waxes can be found that melt at different temperatures to suit specific applications. Typical latent heat capacity is between about 180kJ/kg and 230kJ/kg and a specific heat capacity of perhaps <NUM>. 27Jg-<NUM>K-<NUM> in the liquid phase, and <NUM>. 1Jg-<NUM>K-<NUM> in the solid phase. It can be seen that very considerable amounts of energy can be stored taking using the latent heat of fusion. More energy can also be stored by heating the phase change liquid above its melting point. For example, when electricity costs are relatively low during off-peak periods, the heat pump may be operated to "charge" the thermal energy storage to a higher-than-normal temperature to "overheat" the thermal energy storage.

A suitable choice of wax may be one with a melting point at around <NUM>, such as n-tricosane C<NUM>, or paraffin C<NUM>-C<NUM>, which requires the heat pump to operate at a temperature of around <NUM>, and is capable of heating water to a satisfactory temperature of around <NUM> for general domestic hot water, sufficient for e.g. kitchen taps, shower/bathroom taps. Cold water may be added to a flow to reduce water temperature if desired. Consideration is given to the temperature performance of the heat pump. Generally, the maximum difference between the input and output temperature of the fluid heated by the heat pump is preferably kept in the range of <NUM> to <NUM>, although it can be as high as <NUM>.

While paraffin waxes are a preferred material for use as the thermal energy storage medium, other suitable materials may also be used. For example, salt hydrates are also suitable for latent heat energy storage systems such as the present ones. Salt hydrates in this context are mixtures of inorganic salts and water, with the phase change involving the loss of all or much of their water. At the phase transition, the hydrate crystals are divided into anhydrous (or less aqueous) salt and water. Advantages of salt hydrates are that they have much higher thermal conductivities than paraffin waxes (between <NUM> to <NUM> times higher), and a much smaller volume change with phase transition. A suitable salt hydrate for the current application is Na<NUM>S<NUM>O<NUM>·<NUM><NUM>O, which has a melting point around <NUM> to <NUM>, and latent heat of <NUM>-<NUM> kJ/kg.

<FIG> shows a central heating branch of the water heating system <NUM> of <FIG>. Like elements are indicated by like reference numerals. As can be seen in <FIG>, the heating branch (heating circuit) is a sealed or closed loop comprising elements of a central heating system <NUM> which, for example, includes one or more radiating heating elements/modules disposed in multiple locations around the building.

Water circulating around the heating circuit is heated by heat exchanger <NUM> in the thermal energy storage <NUM>, which is arranged to store thermal energy (heat) extracted from the surroundings by the heat pump <NUM> (optionally also received from the electric heating elements <NUM>). Heated water is output from the water heating system <NUM> via a valve <NUM>-<NUM> (second valve) which controls the flow of the output heated water. The heated water circulates the heating circuit and dissipated by the central heating system <NUM> via one or more radiating heating elements. Cooled water returns from the central heating system <NUM> around the heating circuit to the water heating system via a valve <NUM>-<NUM> (first valve) which controls the flow of the returned water. The pressure of the heating circuit is measured by a first pressure sensor <NUM>-<NUM> and a second pressure sensor <NUM>-<NUM>, and sensor data from the first and second pressure sensors <NUM>-<NUM>, <NUM>-<NUM> is received by the control module <NUM>, which monitors the water pressure of the heating circuit.

As can be seen in <FIG>, the first pressure sensor <NUM>-<NUM> is positioned upstream of the first valve <NUM>-<NUM> and downstream of the second valve <NUM>-<NUM>, while the second pressure sensor <NUM>-<NUM> is positioned downstream of the first valve <NUM>-<NUM>. With this arrangement, the first and second pressure sensors <NUM>-<NUM>, <NUM>-<NUM> and the first and second valves <NUM>-<NUM>, <NUM>-<NUM> are positioned such that, when the first and second valves are in a closed position, the heating circuit (or central heating <NUM>) is fluidly isolated from the water heating system, and the first pressure sensor <NUM>-<NUM> is in a position to measure the isolated water pressure in the heating circuit while the second pressure sensor <NUM>-<NUM> is in a position to measure the isolated water pressure in the water heating system.

For the central heating system to perform optimally, the water pressure within the heating circuit is preferably maintained at a level that is within an optimal operating range. If the pressure in the heating circuit falls below the operating range, the heating circuit may first be fluidly isolated by closing the first valve <NUM>-<NUM>, and then mains water is released into the return flow by operating a third valve <NUM> to an open position so as to increase the water pressure in the heating circuit to a level within the optimal range.

However, there may be different causes that lead to the heating circuit losing pressure. For example, there may be a buildup of air within the heating circuit, a leak somewhere in the heating circuit, such as a valve of one of the radiating heating modules, a damaged pipe or joint, or a leak or fault somewhere in the water heating system. In cases where the loss of pressure is not a result of a fault or a leak, e.g. an air pocket in the heating circuit, then topping up the heating circuit with mains water to remove the air pocket would resolve the issue. However, in cases where the loss of pressure is caused by a fault or a leak, simply restoring the operating pressure in the heating circuit by introducing mains water into the heating circuit will not resolve the issue and may worsen the problem, such as causing further leakage and/or risking heating circuit water back-feeding to water supply (backflow).

It is therefore desirable to determine if there is a leak or fault, and whether the leak or fault is in the heating circuit or the water heating system, before repressurizing the heating circuit. The water heating system <NUM> according to embodiments of the present disclosure enables such a determination to be made through the use of the first and second pressure sensors <NUM>-<NUM>, <NUM>-<NUM> and the first and second valves <NUM>-<NUM>, <NUM>-<NUM>, as illustrated in <FIG> by way of an example.

<FIG> shows a method of detecting water leakages in a water heating system such as the water heating system <NUM>, according to an embodiment. The method is performed by a control unit or control module, such as the control module <NUM>, that is configured to control operations of various elements of the water heating system. In particular, the method may be a computer-implemented method that comprises software instructions which, when executed by one or more processors, such as the one or more processors <NUM>, performs the various steps of the method.

The method begins at S301 when the control module receives sensor data from the first pressure sensor <NUM>-<NUM> (first sensor data) and sensor data from the second pressure sensor <NUM>-<NUM> (second sensor data), indicating a water pressure in the heating circuit.

The control module compares the received first sensor data and second sensor data with a predetermined reference water pressure at S302, and upon determining that the water pressure in the heating circuit is at or above the reference water pressure (NO branch), the method returns to S301 and the control module continues to receive sensor data from the first and second pressure sensors and monitors the water pressure of the heating circuit. If, at S302, the control module determines from the first and/or second sensor data that the water pressure in the heating circuit is below the reference water pressure (YES branch), the control module outputs control signals at S303 to operate the first valve <NUM>-<NUM> and the second valve <NUM>-<NUM> to a closed position in order to fluidly isolate the heating circuit from the water heating system.

Herein, the predetermined reference water pressure may be any suitable water pressure that represents a lower threshold or minimum water pressure at which the heating circuit branch of the water heating system can operate. For example, an optimal operating water pressure, e.g. <NUM> bar, may be set by a human operator during the initial installation of the water heating system or subsequent maintenance of the water heating system and heating circuit. In some embodiments, the reference water pressure may be set at the optimal operating water pressure. However, it may be desirable to take into account of a range of normal operating conditions such as outdoor air temperature, indoor air temperature, atmospheric pressure, etc. when setting the reference water pressure. Thus, in some embodiments, a normal operating pressure range may instead be adopted to account for a normal expected deviation from the optimal operating water pressure, and the reference water pressure may be set at the lower end of the operating pressure range or at the minimum of the operating pressure range. In some embodiments, it may be desirable for the control module to adjust the reference water pressure based on operating conditions of the water heating system, or to provide recommendation or suggestion to a human operator to adjust the reference water pressure based on operating conditions of the water heating system.

After operating the first and second valves <NUM>-<NUM>, <NUM>-<NUM> to the closed position at S303, the control module at <NUM> continues to receive first sensor data from the first pressure sensor <NUM>-<NUM> to monitor the water pressure in the heating circuit (first water pressure) to determine, at S305, whether the first water pressure continues to fall. If the first water pressure continues to fall, this can be used as an indication that the isolated heating circuit is losing water despite water within the heating circuit is not being circulated. Thus, upon determining at S305 that the first water pressure continues to fall (YES branch), the control module determines at <NUM> that there is a leak (or fault) in the heating circuit.

The control module further receives second sensor data from the second pressure sensor <NUM>-<NUM> to monitor the water pressure in the water heating system (second water pressure) at S307, and at S308, determines whether the second water pressure continues to fall. This can be performed simultaneously with, alternately, before, or after S304. If the second water pressure continues to fall, this can be used as an indication that there may be a leak or a fault in the water heating system. Thus, upon determining at S308 that the second water pressure continues to fall (YES branch), the control module determines at S309 that there is a fault or a leak in the water heating system.

The control module may simultaneously or in turn determine whether the first water pressure or the second water pressure continues to fall (S305, S308), and only when both the first water pressure and the second water pressure are determined to remain substantially constant for a sufficient length of time after operating the first and second valves <NUM>-<NUM>, <NUM>-<NUM> to the closed position (NO branch), the control module repressurises the heating circuit at S310 by releasing the second valve <NUM>-<NUM>, to allow water to flow from the water heating system to the heating circuit, while maintaining the first valve <NUM>-<NUM> in the closed position to prevent water from returning from the heating circuit to the water heating system, and operating the third valve <NUM> to introduce mains water into the return route to increase the water pressure in the heating circuit until it reaches a desired pressure, e.g. at or above the reference water pressure, the optimal operating pressure, etc. When the heating circuit has been repressurised to the desired pressure, the control module at <NUM> closes the third valve <NUM> to stop the flow of mains water and releases the first valve <NUM>-<NUM> to allow normal operation of the heating circuit to resume.

According to the invention, it is possible to determine whether there is a leak in the water heating system and/or the heating circuit when the water pressure in the heating circuit falls below the reference water pressure (or a minimum water pressure). Only when it is determined that there is no leak in either the water heating system or the heating circuit would the heating circuit be repressurised. In doing so, it is possible to give an early warning when a leak occurs to prevent a more serious leak caused by late detection and/or pressurising a faulty circuit. Moreover, if there is a leak or fault in the water heating system and the heating circuit is repressurised without the leak or fault being repaired, it can lead to a backflow from the heating circuit into the mains water feeding loop, contaminating water supply with bacteria harmful to health. Through the present invention, it is possible to prevent backflow by only repressurising the heating circuit after it is determined that there is no leak in the water heating system.

In some embodiments, to determine whether the first (second) water pressure continues to fall, the control module may compare first (second) sensor data received at a first time step, T1, with first (second) sensor data received subsequently at a second time step, T2, after a predetermined time interval from T1, and determine whether the first (second) sensor data received at T2 indicates a lower water pressure than the first (second) sensor data received at T1. T1 and T2 may be any suitable and desirable time steps, for example T1 may be the time at which the first (second) water pressure is detected to fall below the reference water pressure, and T2 may be a time after a predetermined interval from T1, e.g. after <NUM> minutes, <NUM> minutes, <NUM> hour, <NUM> day, etc. Present embodiments are not limited to taking only two measurements of water pressure, three, four or more measurements may be taken, and the control module may be configured to only determine that there is a leakage in the water heating system after two, three, four or more consecutive water pressure measurements indicate a continuous fall in water pressure.

In some embodiments, the control module may be configured to only determine that there is a leakage in the heating circuit (the water heating system) when the first (second) water pressure falls below a lower water pressure threshold, or when the difference between two water pressure measurements (sensor data) is above a difference threshold.

In some embodiments, the control module may be configured to determine a rate at which the water pressure falls or decreases based on the sensor data received at T2 and T1 (and any other subsequently received sensor data). For example, the water pressure decrease rate may be determined by dividing the difference in water pressure by the corresponding time interval. In an embodiment, the thus determined water pressure decrease rate can be used to determine an extent or severity of the water leakage by comparing the determined rate with one or more rate thresholds. For example, a lower rate indicates a less severe water leakage while a higher rate indicates a more severe water leakage.

In some embodiments, upon determining at <NUM> that there is a leakage in the heating circuit, and/or upon determining at S309 that there is a leakage in the water heating system, the control module may generate a warning signal to notify a human operator of the water leakage. For example, the warning signal may comprise different form and colour light signal, an audio signal such as a discrete or continuous alarm, a verbal, text or multimedia warning, or a combination thereof.

In an embodiment, the control module may be configured to only generate a warning signal when a difference between the water pressure as indicated by sensor data received at T2 and the water pressure as indicated by sensor data received at T1 exceeds a pressure drop threshold. In doing so, a human operator is only notified if and when the water leakage is deemed problematic.

In an embodiment, the control module may be configured to generate different forms of warning, such as a traffic light system, different speed of flashing light signal, different verbal warning, etc., based on the severity of the water leakage. For example, the control module may select a form of warning based on the extent of the water leakage determined by the rate at which the water pressure of the water heating system is falling. In doing so, a human operator can quickly and easily judge the severity of the leakage and take appropriate action.

In some embodiments, upon determining at <NUM> that there is a leakage in the heating circuit, and/or upon determining at S309 that there is a leakage in the water heating system, the control module may provide on a display an option for a human operator to switch off the water heating system. The display may be an integrated display on the control module or an external display (e.g. a smartphone, a tablet, a computer, etc.) in communication, wirelessly or with a wired connection, with the control module. Alternatively or in addition, the control module may be configured to automatically switch off the water heating system. For example, the control module may be configured to automatically switch off the water heating system if it is determined that the water leakage is severe, and/or if a human operator has not responded to a recommendation to switch off within a predetermined time, wherein the predetermined time may be dependent on the severity or extent of the leakage.

The present techniques may take the form of a computer program product embodied in a computer readable medium having computer readable program code embodied thereon.

Computer program code for carrying out operations of the present techniques may be written in any combination of one or more programming languages, including object-oriented programming languages and conventional procedural programming languages.

For example, program code for carrying out operations of the present techniques may comprise source, object or executable code in a conventional programming language (interpreted or compiled) such as C, or assembly code, code for setting up or controlling an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or code for a hardware description language such as VerilogTM or VHDL (Very high-speed integrated circuit Hardware Description Language).

The program code may execute entirely on the user's computer, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network. Code components may be embodied as procedures, methods or the like, and may comprise sub-components which may take the form of instructions or sequences of instructions at any of the levels of abstraction, from the direct machine instructions of a native instruction set to high-level compiled or interpreted language constructs.

The examples and conditional language recited herein are intended to aid the reader in understanding the principles of the present technology and not to limit its scope to such specifically recited examples and conditions. It will be appreciated that those skilled in the art may devise various arrangements which, although not explicitly described or shown herein, nonetheless embody the principles of the present technology and are included within its scope as defined by the appended claims.

The functions of the various elements shown in the figures, including any functional block labeled as a "processor", may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read-only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage.

Claim 1:
A computer-implemented method of determining a leak in a water heating system (<NUM>), the water heating system (<NUM>) comprising a control module (<NUM>) configured to control operation of the water heating system (<NUM>), at least one water heating module (<NUM>, <NUM>) configured to heat water to be circulated around a sealed heating circuit (<NUM>), a first valve (<NUM>-<NUM>) configured to control water flow returning from the heating circuit (<NUM>) to the water heating system (<NUM>) and a second valve (<NUM>-<NUM>) configured to control water flow from the water heating system (<NUM>) to the heating circuit (<NUM>) , the method being performed by the control module (<NUM>) and comprising:
receiving first sensor data from a first pressure sensor (<NUM>-<NUM>) disposed upstream of the first valve (<NUM>-<NUM>);
receiving second sensor data from a second pressure sensor (<NUM>-<NUM>) disposed downstream of the first valve (<NUM>-<NUM>);
upon determining that the first sensor data and/or the second sensor data indicates a water pressure below a reference water pressure, closing the first valve (<NUM>-<NUM>) and the second valve (<NUM>-<NUM>) to isolate the heating circuit (<NUM>) and the first pressure sensor(<NUM>-<NUM>) from the water heating system (<NUM>) and the second pressure sensor (<NUM>-<NUM>);
monitoring the first sensor data indicating a water pressure in the heating circuit (<NUM>) and the second sensor data indicating a water pressure in the water heating system (<NUM>); and
upon determining that the second sensor data indicates a fall in water pressure, determining a leak in the water heating system (<NUM>),
characterized in that
the water heating system (<NUM>) comprises a third valve (<NUM>) configured to control a flow of mains water into the heating circuit (<NUM>), and in that the method further comprises, upon determining that the water pressure indicated by the first sensor data and the water pressure indicated by the second sensor data remain substantially constant, releasing the first valve (<NUM>-<NUM>) and the third valve (<NUM>) to allow mains water into the heating circuit (<NUM>) to increase the water pressure to at least the reference water pressure.