Heating system and method of operating a heating system

Abstract

A heating system (2) is provided which comprises a combustion region (4) for burning fuel, a flue (8) extending from said combustion region, a temperature sensor (14, 16) arranged to measure a temperature in said combustion region or said flue, and a processing device (18). The processing device is arranged to receive temperature measurements from said temperature sensor, produce a temperature time profile, determine information relating to a plurality of different combustion phases using said temperature time profile and determine output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

Description

[0001] HEATING SYSTEM AND METHOD OF OPERATING A HEATING SYSTEM

[0002] The present invention relates to heating systems such as those comprising wood-burning stoves and methods for operating such systems.

[0003] Many buildings, particularly residential buildings such as houses and apartments, are heated by burning fuel such as wood. The wood is typically contained in a combustion region such as a fireplace or chamber of a stove. Emissions from the combustion are exhausted to the outside of the building through a flue (e.g. provided by a chimney). The flue also encourages air flow into the combustion region to facilitate the burning.

[0004] Over time, pollutants produced by the burning (e.g. soot, creosote) can build up inside the flue. This unwanted build-up can impede airflow through the flue and also pose a fire hazard. Moreover, particulate emissions from the burning can reduce air quality in the vicinity of the flue output. For instance, it has been estimated that emissions from residential wood combustion may be responsible for up to 70% of the organic particulate matter in the atmosphere of European rural locations in winter.

[0005] Fuels typically pass through different phases of combustion as they burn. For instance, the combustion of wood generally involves (1) evaporation of moisture; (2) thermal decomposition of the wood into charcoal, i.e. pyrolysis; and (3) oxidation of the residual charcoal. The different phases of combustion have different efficiencies and can produce varying types and levels of emissions. These variations can make it difficult to estimate accurately the actual performance of a given combustionbased heating system.

[0006] An improved approach may be desired.

[0007] According to a first aspect of the present invention there is provided a heating system comprising: a combustion region for burning fuel; a flue extending from said combustion region; a temperature sensor arranged to measure a temperature in said combustion region or said flue; and a processing device arranged to: receive temperature measurements from said temperature sensor; produce a temperature time profile; determine information relating to a plurality of different combustion phases using said temperature time profile; and determine output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

[0008] According to a second aspect of the present invention there is provided a method of operating a heating system comprising a combustion region and a flue extending from the combustion region, the method comprising: burning fuel in the combustion region; measuring a temperature in the combustion region or the flue to produce a temperature time profile; determining information relating to a plurality of different combustion phases using said temperature time profile; and determining output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

[0009] Thus, it will be recognised by those skilled in the art that using information relating to different combustion phases can improve the quality of data that can be obtained about the heating apparatus. The inventors have recognised that characteristics of the heating apparatus’ operation (e.g. relating to heating efficiency and emissions) can vary substantially between different combustion phases. Therefore, taking information relating to these into account can enable the production of improved insights about heating apparatus operation compared to conventional approaches based on static factors such as the type of fuel and / or apparatus or basic temperature and / or duration of use monitoring.

[0010] The combustion region may be provided by any suitable structure for containing burning fuel known in the art perse. The combustion region may be an enclosed chamber or permanently open on one or more sides. In a set of embodiments, the heating system comprises a wood-burning stove with a firebox defining the combustion region.

[0011] The heating system may comprise one or more air intake paths into the combustion region. The heating system may comprise one or more input dampers for controlling airflow through the one or more air intake paths. Similarly, the heating system may comprise one or more dampers for controlling airflow through the flue. Appropriate control of the intake and / or output dampers may facilitate more optimal heating system operation (e.g. increasing efficiency and / or reducing emissions).

[0012] Different fuels burn in different ways and the fuel burned in the combustion region may comprise any suitable fuel or mixture of fuels known in the art perse. In a set of embodiments, the fuel comprises solid fuel. The burning of solid fuels generally involves an initial heating phase where the fuel is brought up to a temperature at which combustion can be self-sustaining. The solid fuel thermally decomposes to produce solid char and flammable gases which ignite and provide heat to maintain the burning in a flaming phase. Finally, the solid char oxidises flamelessly in a smouldering phase.

[0013] For instance, the fuel may comprise wood fuel such as wooden kindling, logs, split logs, sheets, chips, pellets or dust. The burning of such fuel may include a heating combustion phase, a flaming combustion phase and a smouldering combustion phase. The heating phase of wood burning typically involves the evaporation of water content from the wood. The flaming phase involves biopolymers in the wood being partially or completely decomposed through pyrolysis. The smouldering phase involves gradual oxidisation of charcoal formed in the flaming phase. In some embodiments other fuels may be used such as coal, natural gas or oil.

[0014] The complex and semi-random nature of burning means that the combustion process may not neatly progress from one phase to another (i.e. with well defined start and end times for each phase). There may be overlap between phases and different portions of burning fuel (e.g. different parts of a burning log) may be in different phases of combustion at the same time. However, it will be recognised that at any given time the burning of the fuel will primarily have one or two dominant combustion phases, and that useful insight may be gained using information relating to said dominant combustion phases.

[0015] Information relating to a combustion phase may include one or more of: a start time of a combustion phase; an end time of a combustion phase; a duration of a combustion phase; a number of instances of a combustion phase; a total duration of a combustion phase (e.g. over multiple instances); and an amount or proportion of fuel in a combustion phase. Information relating to a plurality of different combustion phases may include the same information about different phases or different information about different phases. In some embodiments the information relating to a plurality of different combustion phases comprises a combination of information relating to each phase (e.g. a ratio of durations of different combustion phases).

[0016] The temperature time profile may cover a single lighting of the heating system (i.e. from an ignition of fuel in the combustion region until the fuel is used up and potentially including one or more additions of fresh fuel during operation) or even only a portion of a single lighting. However, the temperature time profile may alternatively cover a longer period of operation that covers several lighting cycles. The temperature time profile may span a time period of minutes, hours, days, weeks, months or years. The temperature time profile may be discontinuous, for instance with breaks between lightings of fuel in the combustion region when the heating system is not being used to produce heat. The temperature time profile may comprise a concatenation of separate temperature time profiles from different periods of operation (e.g. corresponding to multiple lightings of fuel in the combustion region). Using a temperature time profile that covers a long period may allow the output data to provide useful long-term insights into the performance of the heating system.

[0017] The information relating to the combustion phases may be determined using the temperature time profile by various different methods. Determining information relating to a combustion phase may comprise comparing the temperature time profile with known temperature characteristics of combustion phases. In a set of embodiments, determining information relating to a combustion phase comprises comparing one or more features of the temperature time profile with one or more features associated with a combustion phase. Features of the temperature time profile may include absolute or relative temperature values, temperature patterns, positive or negative peaks (i.e. local minima / maxima) or gradients.

[0018] For instance, the end of a flaming combustion phase and the start of a smouldering phase may correspond to a positive peak in the combustion temperature, where the temperature changes from rising to falling. A time of such a peak may be identified in the temperature time profile and determined to correspond to an end time of a flaming combustion phase. Conversely, a negative temperature peak where the temperature changes from falling to rising may be associated with the end of a smouldering phase and the start of new flaming combustion phase. Additionally or alternatively, a steep positive temperature time gradient may be associated with a flaming phase and / or a less steep negative temperature time gradient may be associated with a smouldering phase.

[0019] Some features of the temperature time profile (e.g. times at which the temperature is above a threshold value) may be relatively straightforward to identify. However, some embodiments comprise applying one or more statistical methods to the temperature time profile to determine information relating to a combustion phase. For instance, in some embodiments a peak-finding algorithm may be applied to find positive or negative peaks in the temperature time profile (e.g. corresponding to the start / end of combustion phases). In some embodiments a gradient-finding algorithm may be used to find characteristic gradients (e.g. a steep gradient corresponding to a flaming phase) in the temperature time profile (e.g. filtering out high frequency noise).

[0020] In a set of embodiments, a machine learning algorithm is applied to the temperature time profile to determine information relating to a combustion phase. Machine learning algorithms may be particularly suited for finding characteristics features and patterns in the temperature time profile indicative of particular combustion phases. The machine learning algorithm may receive the temperature time profile as an input and produce information relating to a combustion phase or information relating to a plurality of combustion phases as an output. Some embodiments comprise training the machine learning algorithm using training data comprising a set of training temperature time profiles and a corresponding set of combustion phase information (e.g. start and end times of various combustion phases). The training data may be obtained from simulations or empirical combustion tests. Some embodiments comprise training the machine learning algorithm using measured values of particulate and / or gaseous emissions in the flue.

[0021] Once the information relating to different combustion phases has been determined, there are a variety of ways that this can be used to determine useful output data. In some embodiments, the output data may comprise the information itself (e.g. total durations of different combustion phases). In some embodiments, the output data may be determined by using one or more mathematical calculations based on the information relating to different combustion phases. For instance, the output data may comprise or be determined from the result of a weighted function (e.g. a weighted sum) having one or more elements or weightings based on the information relating to different combustion phases (e.g. cumulative durations of flaming and smouldering phases).

[0022] Output data may be determined using the information relating to different combustion phases in combination with other information related to the heating system. This other information may comprise other information determined from the temperature time profile data (e.g. raw temperature data, total burn duration). In some embodiments the other information may comprise fixed parameters of the heating system such as a size, shape, configuration or type of the combustion region or flue, or variable parameters of the heating system such as a total number of burns performed, a type of fuel used or current environmental conditions (e.g. internal building temperature or humidity and / or external weather conditions or forecasts). Information not relating to the temperature time profile used to determine the output data may be input by a user (e.g. to a user device of the heating system) or obtained automatically (e.g. from an internet weather service).

[0023] In a set of embodiments, the output data is determined using an output data machine learning algorithm. Some embodiments comprise training the output data machine learning algorithm using training data comprising a set of training combustion phase information and a corresponding set of output data (e.g. values of particulate or gaseous emissions). The training data may be obtained from simulations or empirical tests. Some embodiments comprise training the output data machine learning algorithm using measured values of particulate and / or gaseous emissions in the flue.

[0024] In a set of embodiments, the output data comprises data relating to one or more deposits in the flue. The output data may comprise an estimate of type and / or quantity one or more materials deposited in the flue. The material may include soot and / or other materials such as creosote.

[0025] The data may relate to material deposited during the period of operation covered by the temperature time profile (i.e. in the period of operation analysed by the processing device). However, in some embodiments previous deposit information may be combined with an estimate of material deposited during the period of operation covered by the temperature time profile (i.e. the most recent material deposits) to produce up-to-date data on material deposits in the flue. Previous deposit information may include previous estimates of material deposited in the flue and / or information relating to a sweeping schedule of the flue (e.g. when the flue was last swept).

[0026] The output data may comprise a quantitative estimate of material deposited in the flue (e.g. an estimated mass, volume or thickness), or a quantitative indication of a level of deposits in the flue (e.g. a “soot index”). The output data may comprise a fire risk level indicating a likelihood of a fire breaking out in the flue.

[0027] Determining an estimate or indication of material deposited in the flue may comprise combining known material deposit data for different combustion phases (e.g. simulated deposition rates, test deposition rates or reference deposition rates for different phases) with the information relating to different combustion phases in the temperature time profile. For instance, a duration of different combustion phases determined from the temperature time profile may be combined with known deposition rates for said combustion phases to determine an estimate of material deposited in the flue.

[0028] In a set of embodiments, the output data comprises data relating to one or more emissions of the heating apparatus, such as one or more particulate emissions of the heating apparatus (e.g. black carbon emissions, PM1 emissions, PM2.5 emissions). Additionally or alternatively the output data comprises data relating to gaseous emissions of the heating apparatus (e.g. CO, CO2, NH3, O2). The output data may comprise an estimate of a quantity of one or more particulates and / or gases emitted from the heating apparatus. The output data may comprise an estimate of a rate at which one or more particulate or gas types has been emitted from the heating apparatus. The output data may comprise a plurality of estimates for different types and / or size ranges of particulates, and / or different gases.

[0029] The heating system may produce different types and quantities of emissions in the different combustion phases. For instance, it has been found that PM1 emissions from burning wood fuel may be at their highest during the flaming phase and at their lowest during the smouldering phase. Determining an estimate of one or more emissions of the heating apparatus may comprising combining using known emissions data for different combustion phases (e.g. simulated emissions data, test emissions data or reference emissions data for different combustion phases) with the information relating to different combustion phases determined from the temperature time profile. For instance, a duration of different combustion phases determined from the temperature time profile may be combined with known emissions rates for different combustion phases to determine an estimate of emissions of the heating system.

[0030] The emissions estimate(s) may cover an entire period of operation (e.g. the period of operation covered by the temperature profile), e.g including multiple different combustion phases and possibly multiple different lightings. In other words, the output data may comprise an estimate of a total quantity of one or more emissions of the heating system over a time period covered by the temperature time profile. Information determined from the temperature time profile may also be combined with previously-gathered or separately-gathered data to produce an emissions estimate that covers a longer time period than just that covered by the temperature time profile (e.g. covering multiple years). For instance, the output data may comprise one or more aggregate emissions estimates (e.g. relating to a most recent period of operation and one or more previous periods of operation), such as a yearly aggregate.

[0031] Additionally or alternatively, the output data may comprise a plurality of estimates of emissions of the heating apparatus in shorter time periods, e.g. corresponding to time periods corresponding to different dominant combustion phases. The output data may comprise a time series of emissions estimates (i.e. an emissions time profile).

[0032] In a set of embodiments, the output data comprises data relating to an efficiency of the heating apparatus (i.e. what proportion of energy contained in the fuel is released as heat). The data may comprise a quantitative estimate of the efficiency of the heating apparatus, or a qualitative indication of efficiency.

[0033] In a set of embodiments, the output data comprises user guidance for improving operation of the heating apparatus, e.g. suggestions for how a user of the heating system can change how they use the heating apparatus to improve its operation.

[0034] In a set of embodiments, the output data comprises guidance for improving an efficiency of the heating system (i.e. how to get more energy out of the fuel). Said guidance may include guidance to use drier fuel, smaller logs and / or a top-down lighting approach (e.g. if the temperature time profile indicates a long ignition phase). The guidance may include guidance to pay closer attention to the fire during operation and / or to add more fuel earlier (e.g. if the temperature time profile indicates a smouldering phase that is longer than optimal).

[0035] In a set of embodiments the output data comprises guidance for reducing one or more emissions by the heating system. For instance, guidance may include suggested settings for input and / or output dampers of the heating system (e.g. to open the damper(s) further to encourage faster burning if long smouldering phases are identified). Additionally or alternatively, guidance for reducing emissions may comprise similar or the same guidance for improving efficiency (e.g. to use drier fuel, smaller logs or a top-down lighting approach, and / or to pay closer attention to the fire during operation and / or to add more fuel earlier).

[0036] In a set of embodiments the output data comprises guidance for reducing the build up of deposits in the flue. Guidance for reducing deposit build-up may comprise similar or the same guidance as that for improving efficiency and / or reducing emissions (e.g. to use drier fuel, smaller logs or a top-down lighting approach, and / or to pay closer attention to the fire during operation and / or to add more fuel earlier).

[0037] The guidance may be provided to the user in many different forms such as text, audio, images, videos or a combination of these.

[0038] In a set of embodiments the heating system comprises or is arranged to communicate with a user device such as a smartphone. The heating system (e.g. the processing device) may be arranged to transmit some or all of the output data to the user device and to cause the user device to output some or all of said data to the user.

[0039] Additionally or alternatively, the output data (e.g. user guidance) may be provided to the user by other less direct means. For instance the heating system may communicate the user guidance (and possibly other output data) to a separate system and to cause said system to forward the user guidance to the user. For instance, the heating system may cause an SMS message or a letter containing user guidance to be sent to the user. In some embodiments the user guidance may be communicated to a third party (e.g. a chimney sweeper or environmental adviser) who can then forward the guidance to the user of the heating system (e.g. verbally).

[0040] A useful temperature time profile may be produced from measurements of temperature in only the combustion region or in only the flue. In a set of embodiments the heating system comprises a single temperature sensor arranged to measure a temperature in the combustion region or in the flue.

[0041] It has been found that there is a generally a strong correlation between the temperatures in the flue and the combustion region, so measuring just the flue can still provide useful insight into actual combustion temperatures. In a set of embodiments the heating system comprises a single temperature sensor arranged to measure a temperature in the flue. It may be easier to install a flue temperature sensor than a combustion region temperature sensor. Furthermore, flue temperatures may be generally lower than combustion region temperatures so using only a flue temperature sensor may allow for the use of a less expensive sensor with lower heat-resistance requirements.

[0042] However, measuring the temperature in the combustion region itself can provide a more direct insight into the combustion process, which may facilitate more accurate identification of different combustion phases. Therefore in some embodiments, the heating system comprises a single temperature sensor arranged to measure a temperature in the combustion region.

[0043] In a set of embodiments the heating system comprises a flue temperature sensor arranged to measure a temperature in the flue and a combustion region temperature sensor arranged to measure a temperature in the combustion region. Measuring the temperatures of both parts of the system may allow for a more complete picture of the combustion. In embodiments which measure flue and combustion region temperatures, separate temperature time profiles may be produced and used to determine the information relating to a plurality of different combustion phase sensors. Additionally or alternatively, a combined temperature time profile may be produced using both sets of measurements and used to determine the information relating to a plurality of different combustion phase sensors. For instance, the flue and combustion region temperature measurements may be averaged.

[0044] The processing device may receive the temperature measurements from the temperature sensor(s) using wired and / or wireless communication. For instance, the processing device and the temperature sensor(s) may be arranged to communicate using radio frequency signals. The processing device and the temperature sensor(s) may communicate over a wireless network (e.g. coordinated by a separate base station) such as a cellular network or a Wi-Fi network. In some embodiments the processing device and the temperature sensor(s) may be arranged to communicate over a direct RF communication link such as a Bluetooth link.

[0045] In some embodiments, the temperature sensor(s) and / or the processing device may be arranged to communicate using a smart home protocol such as Matter. The temperature sensor(s) and / or the processing device may be arranged to join a smart home ecosystem (e.g. Google Home or Apple HomeKit).

[0046] The processing device may be located physically near to the combustion region, e.g. in the same building that is heated by the heating system. However, the processing device may be provided partially or entirely remotely. For instance, the processing device may comprise a server located physically remote from the combustion region. The server may be part of a cloud processing system.

[0047] As explained above the heating system disclosed here can enable the determining of more accurate emissions data. This may be very useful for assessing air quality levels at a local or regional level. Many current estimates of air quality may rely on rough estimates of heating demand and typical or intended heating system operation. However, if a heating system is used more or less optimally than is expected, the actual emissions may be higher or lower than estimated. Because embodiments of the invention determine emissions data based on which combustion phases actually occur detected in the heating system, more accurate local and regional air quality estimates can be obtained.

[0048] When viewed from a third aspect of the present invention there is provided a method of estimating an air quality in a region, the method comprising: operating a plurality of heating systems in said region using the method disclosed herein to determine output data comprising data relating to one or more emissions of the heating apparatuses; estimating an air quality in said region using said output data.

[0049] When viewed from a fourth aspect of the present invention there is a monitoring system for monitoring a heating system comprising a combustion region for burning fuel and a flue extending from said combustion region, the monitoring system comprising: a temperature sensor arranged to measure a temperature in said combustion region or said flue; and a processing device arranged to: receive temperature measurements from said temperature sensor; produce a temperature time profile; determine information relating to a plurality of different combustion phases using said temperature time profile; and determine output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

[0050] Features of any aspect or embodiment described herein may, wherever appropriate, be applied to any other aspect or embodiment described herein. Where reference is made to different embodiments, it should be understood that these are not necessarily distinct but may overlap. It will be understood that, where appropriate, the processing device of the heating system according to the first aspect may be arranged to perform features introduced as part of the method of the second aspect.

[0051] One or more non-limiting examples will now be described, by way of example only, and with reference to the accompanying figures in which:

[0052] Figure 1 is a schematic cross-sectional diagram of a heating system according to an embodiment of the present invention;

[0053] Figure 2 is a graph showing a time profile of a temperature in the flue of the heating system during operation; and

[0054] Figure 3 is a graph showing an emissions profile output by the heating system.

[0055] Figure 1 shows a heating system 2, e.g., located in a residential building. The heating system 2 comprises a combustion region 4 and a chimney stack 6 through which a flue 8 rises vertically. In this embodiment the combustion region 4 is the fire chamber of a wood-burning stove.

[0056] The heating system 2 comprises a combustion region temperature sensor 14, a flue temperature sensor 16, a processing device 18 and a user device 20 (e.g. a smartphone).

[0057] In use, wood fuel 10 (e.g. wooden logs) is burned inside the combustion region 4.

[0058] This produces (useful) heat along with gaseous and particulate emissions which are exhausted through the flue 8. Over time, soot and creosote deposits 12 build up on the interior walls of the flue 8.

[0059] These deposits 12 can inhibit the flow of air through the flue 8. They are also flammable and thus introduce a risk of chimney fire.

[0060] The temperature sensors 14, 16 measure continuously the temperature within the combustion region 4 and the flue 6 respectively (i.e. the temperature of gases within the fire chamber and the flue). These temperature measurements are transmitted wirelessly (e.g. over a Bluetooth or Wi-Fi connection) to the processing device 18.

[0061] The processing device 18 logs the temperature measurements as the wood fuel 10 is burned in the combustion region 4 to produce two temperature time profiles. An example temperature time profile 100 for the flue 8 is shown in Figure 2.

[0062] When wood fuel 10 is burned in the combustion region 4 it passes through several combustion phases. Each phase of the burning results in different types and / or levels of gaseous and particulate emissions.

[0063] Not all of the wood fuel 10 present in the combustion region 4 at a given time may be experiencing exactly the same phase of combustion (e.g. if fresh wood is added to the combustion region 4 whilst previous wood is still smouldering). However, the approximate start of different dominant combustion phases can be identified in the temperature time profile 100.

[0064] First, from t=0, the wood undergoes an initial drying phase in which water content evaporates from the fuel as it is heated.

[0065] After moisture evaporation, the temperature in the combustion region 4 rises suddenly, reaching relatively high values (e.g. 350 - 750°C) and the combustion enters a flaming phase at around t1. During this period there may be visible flames in the combustion region 4 with temperature fluctuations related to flame intensity variations and the combustion of gaseous compounds resulting from the devolatilization of the wood. In the flaming phase, biopolymers such as cellulose, hemicelluloses and lignin are partially or completely decomposed through pyrolysis. This produces residual black carbon material called char. Char is formed continuously until the combustible volatile material is consumed. At around t2 the combustion enters a smouldering phase which involves slower and flameless oxidation of the char.

[0066] At time t3, fresh wood fuel 10 is added to the fire and the combustion quickly returns to the flaming phase. This cycle of flaming and smouldering repeats until a final log finishes flaming at t4, after which the temperature gradually decreases in a final smouldering phase until the end of the time profile 100.

[0067] The processing device 18 uses the temperature time profiles to identify when and for how long different combustion phases dominate in the combustion region 4. For instance, the processing device 18 may use statistical analysis methods to identify negative peaks in the time profiles that correspond to the start of flaming combustion phases and positive peaks that correspond to the start of smouldering phases.

[0068] The processing device 18 calculates a total duration of flaming and a total duration of smouldering. The processing device 18 also obtains other relevant information about the heating system 2 including the type of chimney 6, the type of combustion region 4 and current weather conditions in the vicinity of the heating system 2.

[0069] The processing device 18 uses all of this information (e.g. in a weighted function) to determine various output data relating to the heating system.

[0070] The output data includes an indication of an expected level (e.g. thickness) of deposits 12 in the flue 8 (a “soot index”).

[0071] The output data also includes an emissions time profile for the heating system 2 (i.e. how the emissions of the heating system 2 vary over its operation).

[0072] Figure 3 shows an example of an emissions profile for a section 300 of the temperature time profile 100 which includes part of a flaming phase and part of a smouldering phase. It can be observed that the concentration of particulate matter (PM) emissions 302 peaks during the flaming phase. The gaseous CO2 emissions 304 peak a little later. The output data also includes an estimated efficiency of the heating system (i.e. how much energy in the fuel is being usefully extracted as heat energy).

[0073] Finally, the output data includes guidance for a user on how to operate of the heating system 2 in future to reduce soot build-up, reduce emissions and improve efficiency.

[0074] All of the output data is transmitted from the processing device 18 to the user device 20. Some or all of the output data may be viewed by a user on a display of the user device 20.

[0075] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

Claims1. A heating system comprising: a combustion region for burning fuel; a flue extending from said combustion region; a temperature sensor arranged to measure a temperature in said combustion region or said flue; and a processing device arranged to: receive temperature measurements from said temperature sensor; produce a temperature time profile; determine information relating to a plurality of different combustion phases using said temperature time profile; and determine output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

2. The heating system of claim 1, wherein the fuel comprises wood fuel and the burning of the fuel comprises a heating combustion phase, a flaming combustion phase and a smouldering combustion phase.

3. The heating system of any preceding claim, wherein information relating to a combustion phase includes one or more of: a start time of a combustion phase; an end time of a combustion phase; a duration of a combustion phase; a number of instances of a combustion phase; a total duration of a combustion phase; and an amount or proportion of fuel in a combustion phase.

4. The heating system of any preceding claim, wherein the processing device is arranged to determine information relating to a combustion phase by comparing one or more features of the temperature time profile with one or more features associated with a combustion phase.

5. The heating system of claim 4, wherein the one or more features of the temperature time profile include one or more of: absolute or relative temperature values, temperature patterns, positive or negative peaks and gradients.

6. The heating system of any preceding claim, wherein the processing device is arranged to determine information relating to a combustion phase by applying one or more statistical methods to the temperature time profile.

7. The heating system of any preceding claim, wherein the processing device is arranged to determine information relating to a combustion phase by applying a machine learning algorithm to the temperature time profile.

8. The heating system of claim 7, wherein the machine learning algorithm is trained using training data comprising a set of training temperature time profiles and a corresponding set of combustion phase information.

9. The heating system of any preceding claim, wherein the output data comprises or is determined from the result of a weighted function having one or more elements or weightings based on the information relating to different combustion phases.

10. The heating system of any preceding claim, wherein the processing device is arranged to determine output data using the information relating to different combustion phases in combination with other information related to the heating system.

11. The heating system of claim 10, wherein the other information related to the heating system comprises fixed parameters of the heating system or variable parameters of the heating system.

12. The heating system of any preceding claim, wherein the processing device is arranged to determine the output data using an output data machine learning algorithm, said output data machine learning algorithm being trained using training data comprising a set of training combustion phase information and a corresponding set of values of particulate or gaseous emissions.

13. The heating system of any preceding claim, wherein the output data comprises data relating to one or more deposits in the flue.

14. The heating system of any preceding claim, wherein the output data comprises an estimate of a quantity of one or more particulates and / or gases emitted from the heating apparatus.

15. The heating system of claim 14, wherein the output data comprises a time series of emissions estimates.

16. The heating system of any preceding claim, wherein the output data comprises data relating to an efficiency of the heating apparatus.

17. The heating system of any preceding claim, wherein the output data comprises user guidance for improving operation of the heating apparatus.

18. The heating system of any preceding claim, arranged to transmit some or all of the output data to a user device.

19. The heating system of any preceding claim comprising a single temperature sensor arranged to measure a temperature in the combustion region or a single temperature sensor arranged to measure a temperature in the flue.

20. The heating system of any of claims 1-18, comprising a flue temperature sensor arranged to measure a temperature in the flue and a combustion region temperature sensor arranged to measure a temperature in the combustion region.

21. The heating system of any preceding claim, wherein the processing device and the temperature sensor(s) are arranged to communicate using radio frequency signals.

22. The heating system of any preceding claim, comprising a wood-burning stove with a firebox defining the combustion region.

23. A method of operating a heating system comprising a combustion region and a flue extending from the combustion region, the method comprising: burning fuel in the combustion region;measuring a temperature in the combustion region or the flue to produce a temperature time profile; determining information relating to a plurality of different combustion phases using said temperature time profile; and determining output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

24. A method of estimating an air quality in a region, the method comprising: operating a plurality of heating systems in said region using the method of claim 23 to determine output data comprising data relating to one or more emissions of the heating apparatuses; and estimating an air quality in said region using said output data.

25. A monitoring system for monitoring a heating system comprising a combustion region for burning fuel and a flue extending from said combustion region, the monitoring system comprising: a temperature sensor arranged to measure a temperature in said combustion region or said flue; and a processing device arranged to: receive temperature measurements from said temperature sensor; produce a temperature time profile; determine information relating to a plurality of different combustion phases using said temperature time profile; and determine output data relating to the heating apparatus using the information relating to the plurality of different combustion phases.

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