EP4649269A1

EP4649269A1 - Electric space heater

Info

Publication number: EP4649269A1
Application number: EP24701040.8A
Authority: EP
Inventors: Matthew White
Original assignee: Digital Heat Ltd
Current assignee: Digital Heat Ltd
Priority date: 2023-01-14
Filing date: 2024-01-10
Publication date: 2025-11-19
Also published as: GB2619116B; JP2026505161A; CN120584263A; GB202300582D0; WO2024149997A1; GB2619116A

Abstract

There is disclosed an electric space heater (1) comprising: a first electric heating arrangement (8) arranged to be powered by both an AC power supply (22) and a DC power supply (20); and a controller (24) arranged to control distribution of power to the first heating arrangement from the DC power supply and the AC power supply.

Description

Title: Electric space heater

Field

This invention relates to electric space heaters. In particular, but not exclusively, the invention relates to independent electric space heaters for heating spaces on demand.

Background

A space heater is an independent heating device that is designed to heat a small area, or "space," rather than an entire building or large room. Space heaters can be used to supplement central heating or to provide heat in a small area where it is needed.

Space heaters that use electricity as a fuel source are known - they can be powered by plugging into an electrical outlet to access a mains AC power supply. Some space heaters have a built-in thermostat, which allows the user to set the desired temperature, and they may also have safety features such as automatic shut-off and tip-over protection.

Space heaters are often used in small rooms or spaces where it is difficult or expensive to heat with a central heating system, or where additional heat is needed on a temporary basis. They can be an energy-efficient and cost-effective way to heat small areas, but should be used with caution to avoid the risk of fire or other hazards. Electric space heaters work by using electricity (e.g. mains AC supply) to power a heating element, such as a coil or a block of metal. When the heating element is energized, it becomes hot and begins to transfer heat to the surrounding air or fluid (e.g. oil) or other objects.

Electric heaters of many types include:

1. Convection heaters: These heaters work by using electricity to power a heating element, such as a coil or a block of metal, which becomes energised, becomes hot and begins to transfer heat to the surrounding air or fluid (e.g. oil) or other objects to heat the air around it, creating a current of warm air that circulates throughout a room. The heat is generated by the resistance of the heating element to the flow of electricity. As the electricity passes through the element, it encounters resistance, which causes the element to become hot. In a convection heater, the heating element is usually located within a housing or enclosure that is designed to allow air to circulate around it. As the air is heated by the element, it rises and is replaced by cooler air from the room, creating a current of warm air that circulates throughout the space. This process helps to evenly distribute the heat and raise the overall temperature of the room.

2. Radiant heaters: Radiant heaters work by using electricity to power a heating element, such as a coil or a block of metal. When the heating element is energised, it becomes hot and begins to transfer heat to the surrounding objects and surfaces by emitting infrared radiation. Infrared radiation is a type of electromagnetic radiation that has a longer wavelength than visible light and is not visible to the human eye. It is able to pass through the air and is absorbed by objects and surfaces that it comes into contact with, raising their temperature. The heat is generated by the resistance of the heating element to the flow of electricity. As the electricity passes through the element, it encounters resistance, which causes the element to become hot. In a radiant heater, the heating element is usually located within a housing or enclosure that is designed to allow the infrared radiation to be emitted into the surrounding space. As the radiation is absorbed by objects and surfaces in the room, it helps to raise the overall temperature of the space.

3. Fan heaters: Fan heaters work by using electricity to power a heating element, such as a coil or a block of metal, and a fan. When the heating element is energized, it becomes hot and begins to transfer heat to the surrounding air or objects. At the same time, the fan is used to blow the heated air into the room, creating a current of warm air that helps to raise the temperature of the space. The heat is generated by the resistance of the heating element to the flow of electricity. As the electricity passes through the element, it encounters resistance, which causes the element to become hot. Fan heaters are generally very efficient and can be used to heat a small area or an entire room.

4. Baseboard heaters: These heaters are installed along the baseboard of a wall and use a heating element to warm the air that is drawn through them by natural convection.

5. Oil Filled Radiators: Oil-filled radiators are a type of electric heater that uses oil as a heat-transfer fluid. They work by heating up the oil inside the radiator using electricity. As the oil is heated, it begins to circulate through the radiator, transferring its heat to the metal fins of the radiator. These fins then radiate the heat outward, warming the surrounding air. The oil inside the radiator never actually boils or evaporates, so it does not need to be replaced. This makes oil-filled radiators very efficient and long- lasting. They are also safe to use, as there is no risk of the oil catching fire or producing harmful fumes. Oil-filled radiators are slow to heat up, but they retain their heat for a long time, making them a good choice for providing steady, consistent heat in a room. They are also relatively quiet and do not produce the dry, hot air that some other types of heaters do. Inside the radiator, there is a heating element that is made of a conductive material such as copper or aluminium. When electricity flows through the heating element, it generates heat due to resistance to the flow of electricity. This heat is then transferred to the oil in the radiator, causing it to rise in temperature. The heating element is typically located near the bottom of the radiator, where the oil is the coolest. As the oil is heated, it becomes less dense and begins to rise through the radiator. As it rises, it passes through the metal fins of the radiator, which transfer the heat to the surrounding air. The hot oil then flows back down to the bottom of the radiator, where it is reheated by the heating element and the process starts over again. The temperature of the oil and the heat output of the radiator can be controlled by a thermostat, which turns the heating element on and off as needed to maintain the desired temperature and/or to provide a safety cut-off mechanism.

Electric heaters are generally efficient and can be used to heat a small area or an entire room. They are also easy to install and operate and do not produce harmful emissions.

The inventors have realised that a better electric space heater can be produced and have created the claimed solution.

Summary

According to a first aspect of the present invention, there is provided a fluid heater as claimed in claim 1.

Advantageously, an electric space heater that can use a combination of DC power and AC power (i.e. need not rely on AC input) is provided. This type of heater is able to make intelligent use of available electric power supply options and thereby work more efficiently whilst providing high performance and in an eco-friendly manner. The intelligent mix of AC and DC power sources reduces the risk of overwhelming household electric supplies or a local grid (e.g. at peak demand times when many devices (not only heating devices) may be plugged into mains AC). Furthermore, a fluid heater having a typically higher peak power may be provided - e.g. when a space first needs to be heated up from cold, the inventive heater can be operated at a peak power that is significantly higher than is possible using mains AC alone. Furthermore, intelligent use of DC power is useful in a mains AC power cut scenario. The ability to control and balance use of DC supplied electricity to power the electric heating arrangement in conjunction with the usual AC electricity power supply can also solve a responsiveness problem: it is possible to heat up with combined AC+DC more quickly than compared to mains AC only. This means a space can be warmed faster from when a heating demand is made (e.g. via a direct request from a user, or via an indirect or automated system that forecasts a user’s anticipated needs). In some aspects, a space can begin to be heated before a person arrives in the space - this is more efficient; and better from a user experience perspective.

The inventive heater can help to avoid circuit overload, e.g. by avoiding reaching a mains AC delivery limit: e.g. running a few spot heaters can overwhelm a local grid, such as the main circuit for a typical home - assuming 3kW space heaters, only 8 can be run for a home (before the mains supply is overloaded at 100A). There are usually other loads on a home or office AC circuit to account for too (especially at busy, high demand times of day. The limit on power that can be drawn from a domestic power socket depends on the specific country and the type of outlet being used. In the United States, for example, a standard 120-volt outlet can provide up to 15 amps of current, for a maximum power draw of 1,800 watts. However, some outlets in the US are rated for 20 amps and can provide up to 2,400 watts. These are the maximum ratings, and it is not recommended to continuously operate devices at or near these limits, as it can be dangerous and may cause damage to an electrical system. In the UK, the standard domestic power outlet is rated at 230 volts and 13 amps, for a maximum power draw of 2,990 watts. However, like in the US, these are the maximum ratings and it is not recommended to continuously operate devices at or near these limits. This is because the rating of the outlet is also dependent on the overall electrical system of the building and the wiring in the walls.

By using the DC power supply of this invention instead of, or in addition to, the mains AC power supply, the electricity demand loading on a domestic circuit can be managed by smoothing or reducing its peak (across the household, for example). So, for example, DC power supply can be recharged in household low-demand times, e.g. at night when people are asleep, or when a heater is switched off when a person leaves a room and the room becomes unoccupied. In household high-demand times, e.g. morning rush (when lots of different devices are plugged in and using grid AC), the DC is arranged to support or boost the AC, e.g. depending on specific needs.

In some examples of the invention, it is possible to use the DC supply to provide extra power and heating in short bursts when most needed, such as when first heating a space from cold.

In some examples, the maximum power via heating from the combined AC and DC power supplies is greater than that achievable using the AC supply alone. Typically, in some examples, at least a 25% heating boost (in delivered kW heating power) can be provided when needed. This allows aggressive heating for short periods when needed, which can be subsequently gradually phased away / removed abruptly once temperature conditions in the space reach a measured threshold, or once a user directly indicates that the aggressive heating is no longer required. The electric heating element can then run on the AC power supply only.

In times of potentially high AC grid load, it may be desirable to reduce the amount of mains AC being used (e.g. whilst maintaining the same heat output, but not necessarily - may be slightly decreased heat output, or may even be increased) to power the electric heating arrangement. In such cases, the controller of the inventive heater may be arranged to switch between using AC and DC power supplies to power the arrangement in order to reduce load on the grid. In some cases, the switching between using AC and DC may occur at about 50 Hz to reduce the average power taken from the AC mains supply. If the AC mains supply operates at 50 Hz, and the DC power supply output is matched to the RMS average output of the mains supply, then the DC power supply can satisfy about half of the heating demand whilst maintaining the same heating output as if using AC only in a traditional electric space heater. The inventive space heater would reduce its load on the AC grid by about half in that scenario, without delivering any less heat. Other AC + DC balancing configurations will be apparent to the skilled person dependent upon the specific needs or desires of a particular system.

In some, or all, examples the AC power supply may be arranged to heat a space (continuously) for a relatively long duration; DC power supply is arranged to: heat the space more powerfully for a relatively short duration, by supplementing the AC power supply; reduce burden on the AC grid circuit; or amplify heating ability of the space heater beyond the AC-only capability; or work in a lower power mode than mains AC to reduce overall AC energy used; or work in a lower power mode to reduce overall cost compared to using AC; or allow safe non-plugged in (i.e. non- AC) running for short periods or very low output long periods.

Optional features of the invention are as claimed in the dependent claims - various advantages are thereby provided as discussed in the detailed description. These optional features add efficiency and intelligence to the inventive heater setup. Any of these optional features may be combined with any other of the optional features as will be appreciated by those skilled in this art.

Brief Description of Drawings

Embodiments will now be described by way of example only with reference to the accompanying drawings, in which:

Figures 1 to 3 show schematic views of electric space heaters according to first, second and third aspects of the invention;

Figures 4a to 4d show views from different angles and a cross-section view of a fan blower space heater according to another aspect of the invention;

Figures 5a to 5e show views from different angles and cross-section views of a fan blower space heater according to another aspect of the invention;

Figures 6a to 6e show views from different angles and cross-section views of the fan blower space heater of figures 5a to 5e in a first working configuration;

Figures 7a to 7e show views from different angles and cross-section views of a convection space heater according to another aspect of the invention;

Figures 8a to 8d show views from different angles and a cross-section view of an oil-filled radiator space heater according to another aspect of the invention; and

Figures 9a to 9d show views from different angles and a cross-section view of an oil-filled radiator space heater according to another aspect of the invention.

Description of Embodiments

The exemplary embodiments described in the detailed description and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the scope of the invention. Various embodiments are described. The specific embodiments are not intended as an exhaustive description or as a limitation to the broader discussed and claimed aspects. Features described in conjunction with a particular embodiment are not necessarily limited to that embodiment and can be incorporated into any other embodiment(s). Protection afforded by any applicable doctrine of equivalents is retained to its fullest extent.

Terms such as up, down, top, bottom, left, right, inner, outer, vertical, upstanding etc. have been used to describe the invention simply and clearly. These terms are not to be interpreted in a manner that would be limiting. The person skilled in the art will envisage other suitable embodiments within the scope of the invention.

Referring to figure 1, there is shown schematically an electric space heater 1. Various aspects of the heater will be described in detail with reference to non-limiting examples. Other details will be apparent to the skilled person. In particular, aspects (including undescribed aspects) of known electric space heaters can be incorporated and used with this invention by the skilled person. The electric space heater is an independent space heater in that it is independent of any central heating system; in some embodiments, it is a portable heating device that is designed to heat a small area, or "space," rather than an entire room or building. In this embodiment, the space heater is also independent in that it is not reliant on other sources of energy (e.g. in the same way as a central heating radiator that is dependent on heating from a central heater within a connected heating water circuit). Such central heating systems have access to a powerful heater that is located within the circuit; independent space heaters do not. The skilled person will be able to adapt the described embodiments to electric space heater types other than those described. As is known, these heater types can be used to directly heat air surrounding the heater, or to heat surrounding air via a heating fluid (such as oil in an oil-filled radiator), or to heat surrounding air via another medium, such as a heating block, e.g. a ceramic heating block.

Prior electric space heaters that heat surrounding air are well known in the field. Air typical flows past or through such heaters. In some cases, air to be heated flows past electric heating elements (e.g. in a fan blower space heater); in other cases, electric heating elements are encased in a housing along with a heating fluid, such as heating oil in an air filled radiator, and the radiator heats air around the outside of the housing, case

In this example, the independent electric space heater 1 is a convection heater. In other examples, the heater may be a fan blower heater or an oil-filled radiator, or any other type of other electric space heater. The heater 1 comprises a heater housing 2 arranged to house its components. Often the heater of this invention will be required to be portable. In many examples, this invention includes features that make the heater compact to allow the heater to be easily carried and moved even though the inventive heater comprises new components (as will be described in more detail below).

The heater 1 is arranged to heat surrounding air. Relatively cold air arrives at the heater 1 (schematically illustrated by a virtual input pipe 4), is heated and then relatively hot air exits the heater 1 to the surrounding environment (illustrated by a virtual pipe 6). These virtual pipes are depicted in the drawings to help clearly describe the invention only; typically a convection space heater creates air currents in a space due to temperature differences between heated and unheated air (as previously described) - there are no physical pipelines in this embodiment.

The heater 1 comprises a first electric heating arrangement comprising a first electric heating element 8 and a case 10, which is located within the housing 2 between the input 4 and output 6, and arranged to contain the electric heating element 8. The case 10 electric heating arrangement is arranged to heat air passing through the heater and past the case 10. The case is a protective case to protect the exposed element 8 from wear and tear. In other examples the case may not be present; the heating arrangement is exposed.

In some embodiments, the electric heating arrangement may comprise multiple electric heating elements.

As per this invention, the first electric heating element 8 communicates with both a DC power supply and an AC power supply such that it can be powered by either or both of them. In embodiments in which the electric heating arrangement comprises multiple electric heating elements, some may be arranged to be powered by AC only and some may be arranged to be powered by DC only and some may be arranged to be powered by both AC and DC. Any combination of these options is possible, as will be apparent to the skilled person. The grid sees a lower average AC power demand than if using AC at full pelt or continuously all the time. Also, the domestic dwelling (where such heaters are often used) sees less of a peak AC usage too - therefore, the inventive system is less likely to trip electric or overheat things such as a plug socket (can cause fire). In some examples, the controller is arranged to heat the electric heating arrangement via: a blend of AC and DC; or AC only and DC only at different times or for different use cases; or any combination thereof. In this example, the DC power supply is in the form of a battery pack 20, which is part of the heater 1 and is also located within the housing 2. In other examples, the DC power supply may be located externally of the heater.

In this example, the AC power supply comprises mains electric power 22 (also known as "utility power", "household power", "household electricity", "house current", "powerline", "domestic power", "wall power", "line power", "AC power”, "city power", "street power", “hydro”).

The heater also comprises a controller 24 arranged to control distribution of power to the first heating element 8 from the DC and AC power supplies 20, 22. The controller may be implemented in hardware or software or a combination thereof, as will be apparent to those skilled in the art.

In some examples, the controller is computer controlled and arranged to control the amount of heating supplied to the surrounding air based on or in response to any one or more control factors, the control factors comprising: capacity of the heating arrangement; capacity of the or each heating element; amount of heating required; air input temperature at an input point in the heater housing; air output temperature at an output point in the heater housing; air temperature at any predetermined point in heater housing; air temperature at any predetermined point outside the heater housing (e.g. in the space to be heated); amount of heating capacity available from the first heating element; instantaneous demand for heating; forecasted demand for heating; and flow rate of air to be heated.

Furthermore, in some examples, the fluid heater comprises one or more sensors (not shown) arranged to sense information relating to the one or more control factors and to provide said control factor information to the controller. Some of the sensors are located inside the heater housing (e.g. to measure air temperature or air or heating fluid flow rates within the heater). Some of the sensors are located outside the heater housing (e.g. to measure air temperature or air flow rates at a desired location outside the heater, such as in a room of a building). The controller acts in response to information from such sensors to instruct heating of the fluid by the electric heating arrangement.

In some examples, the controller may have a memory (not shown) associated therewith (either integrally or separately), the memory being arranged to store information about any one or more aspects of the system, such as historic or sensed information relating to any of the control factors, control factor information, sensed information from any of the sensors, desired output information (e.g. desired room temperature). The controller is able to access information from the memory in a known manner. The controller and memory may be implemented in a standard computerised network and system.

In this example, the controller 24 comprises (not shown) a hardware thermostatic controller and optionally a further GUI thermostatic controller such that a user can easily input desired heating demands and easily receive feedback on heating operating parameters in a known manner.

In this example, the controller 24 also includes (not shown) an AC power supply adapter arranged to interface with the external AC power supply 22 to deliver AC power to the heating element 8 within a desired power configuration. Although not present in this embodiment, in some embodiments, similarly a DC power supply adapter located between the DC power supply and the heating element is arranged to interface with the DC power supply 22 to deliver DC power to the heating element within a desired power configuration.

The controller is arranged to take into account a number of factors when controlling apportionment of power to the heating element. In some cases (at any given time), it will be desirable to use the DC supply only; in other cases (at any given time), it will be desirable to use the AC supply only; and in other cases (at any given time), it will be desirable to use a combination of the DC and AC power supplies. Examples scenarios are listed in the Summary section above; other scenarios will be apparent to the skilled reader. The controller is configured to control relative distribution of power from the DC and AC power sources taking into account any one or more of: the capacity of the heating arrangement; the capacity of the or each heating element (e.g. what is the maximum safe load (e.g. peak power or duration of continuous powering) of a particular heating element); the capacity of the or each power supply; instantaneous demand for heating (e.g. has the heater just been turned on / has the or each heating been just been activated from cold); forecasted demand for heating; and instantaneous or forecasted available supply type (e.g. is there much DC battery capacity left, or is the load on the AC grid high at the moment). The controller may also be configured to provide a seamless switch from predominantly using the DC power supply to predominantly using the AC power supply, e.g. as the DC battery exhausts, the AC power supply takes over gradually or suddenly, whilst the power output stays substantially constant or at a desired level, or as an anticipated or measured peak AC load time is entered or approaching, then the DC power supply is utilised gradually or suddenly. The controller may also control smart charging of the DC power supply such that heat and charge level (of the DC battery) are taken into account when controlling charging (e.g. whether to charge aggressively / quickly or more slowly). In some examples, the DC power supply is configured to be simultaneously chargeable and to power the electric heating arrangement at the same time. If the DC power supply comprises a battery pack having multiple cells, the controller is arranged to simultaneously: use some cells of the DC power supply for heating the electric heating arrangement; and charge some (or all) other cells of the DC power supply.

In some examples, the first heating arrangement may have a preferred power demand range and the controller is arranged to supply power within the preferred power demand range whilst varying the proportion of AC to DC power to the first heating element from 0:100 to 100:0 of AC:DC. In cases where demand is met entirely or largely by the AC power supply, a relatively low or zero DC power supply may be needed. In some examples, the DC power supply is of a size such that 100% of the heating demand cannot be met solely by the DC power source. In other examples, a large DC power supply is provided and such demand can be met solely by the DC power source. Some examples are described later in this document.

In this example, the heater is a fully electric heater, i.e. the heat source is all electric. In other examples, the heater may be part electric, e.g. part electric and part gas, or part electric and part other combustible fuel - a suitable combustible fuel may be a combustible fluid such as natural gas, hydrogen gas, or propane gas or methane gas, or ethane gas, or butane gas, or a suitable combustible oil or a combustible solid or mulch, such as woodchip or wood pellet, or any combination thereof. In this way, some of the heating power is provided by the electric (DC and AC) component and some of it is provided by more traditional burnt fuel. This can help to add redundancy within the system, or can be used to operate efficiently in an environment where one or other power source is scarce. In some examples of this invention, the combined DC and AC power sources are large enough to supply all or nearly all of the power output of a typical heater if required. In other examples, the combustible fluid may provide most of the power output, whilst the electric sources provide a supplementary heating effect. For example, the electric sources may be used particularly when the heater is first started up, since the combustion fuel alone may be slow to heat up a space. In some cases, this is because the combustible fluid may be heating up via a heating block (or similar), which takes time (e.g. minutes) to warm up from cold.

Referring to figure 2, there is shown schematically an electric space heater 31 according to another example. V rious aspects of the heater 31 will be described in detail with reference to non-limiting examples. Other details will be apparent to the skilled person. In particular, aspects (including undescribed aspects) of known electric space heater systems can be incorporated and used with this invention by the skilled person.

In this example, the independent electric space heater 31 is a convection heater. In other examples, the heater may be a fan blower heater or an oil-filled radiator, or any other type of other electric space heater. The heater 31 comprises a heater housing 32 arranged to house its components. Often the heater of this invention will be required to be portable. In many examples, this invention includes features that make the heater compact to allow the heater to be easily carried and moved even though the inventive heater comprises new components (as will be described in more detail below).

The heater 31 is arranged to heat surrounding air. Relatively cold air arrives at the heater 31 (schematically illustrated by a virtual input pipe 34), is heated and then relatively hot air exits the heater 31 to the surrounding environment (illustrated by a virtual pipe 36). These virtual pipes are depicted in the drawings to help clearly describe the invention only; typically a convection space heater creates air currents in a space due to temperature differences between heated and unheated air (as previously described) - there are no physical pipelines in this embodiment.

The heater 31 comprises a first electric heating arrangement comprising a first electric heating element 38 and a case 40, which is located within the housing 32 between the input 34 and output 36, and arranged to contain the electric heating element 38. The case 40 electric heating arrangement is arranged to heat air passing through the heater and past the case 40. The case is a protective case to protect the exposed element 38 from wear and tear. In other examples the case may not be present; the heating arrangement is exposed.

As per this invention, the first electric heating element 38 communicates with both a DC power supply and an AC power supply such that it can be powered by either or both of them.

In embodiments in which the electric heating arrangement comprises multiple electric heating elements, some may be arranged to be powered by AC only and some may be arranged to be powered by DC only and some may be arranged to be powered by both AC and DC. Any combination of these options is possible, as will be apparent to the skilled person.

In this example, the DC power supply is in the form of a battery pack 50, which is part of the heater 31 and is also located within the housing 32. In other examples, the DC power supply may be located externally of the heater.

In this example, the AC power supply comprises mains electric power 52.

The heater also comprises a controller 54 arranged to control distribution of power to the first heating element 38 from the DC and AC power supplies 50, 52. The controller may be implemented in hardware or software or a combination thereof, as will be apparent to those skilled in the art.

In this example, the controller 54 comprises (not shown) a hardware thermostatic controller and optionally a further GUI thermostatic controller such that a user can easily input desired fluid heating demands and easily receive feedback on fluid heating operating parameters in a known manner.

In this example, the controller 54 also includes (not shown) an AC power supply adapter arranged to interface with the external AC power supply 52 to deliver AC power to the heating element 38 within a desired power configuration.

The controller 54 also includes a DC- AC converter (not shown separately from the controller in the drawings) located between the DC power supply and the heating element and arranged to interface with the DC power supply 22 to convert DC to AC in a known manner before delivering power to the heating element within a desired power configuration.

In this example, the controller is arranged to control combining of the outputs from the AC power supply and the DC power supply to deliver only AC power to the heating element. A benefit of this feature is to make the input circuitry to the heating element simpler than when providing both AC and DC directly to the heating element (resulting in fewer circuit connections to the electric heating element, which in turn results in enhanced for reliability, maintenance and space savings).

In other examples, the controller may be arranged to control combining of the outputs from the AC power supply and the DC power supply to achieve a different goal.

In other examples, the heater may (instead of a DC-AC converter) comprise an AC-DC converter located between the AC power supply and the heating element and arranged to interface with the AC power supply to convert AC to DC in a known manner before delivering only DC power to the heating element within a desired power configuration. Again, a benefit of this feature is to make the input circuitry to the heating element simpler than when providing both AC and DC directly to the heating element. In this scenario, in some embodiments, the AC-DC converter may be located inside the heater housing 32, and in other embodiments may be located outside the heater housing.

The controller is arranged to take into account a number of factors when controlling apportionment of power to the heating element. These have been discussed above in relation to the example of figure 1, and apply to this example too. The controller is configured to control relative distribution of power from the DC and AC power sources taking into account factors discussed above in relation to the example of figure 1, and apply to this example too.

In some examples, the first heating element may have a preferred power demand range and the controller is arranged to supply power within the preferred power demand range whilst varying the proportion of AC to DC power to the first heating element from 0:100 to 100:0 of AC:DC. Such examples discussed above in relation to the example of figure 1 apply to this example too.

In this example, the heater is a fully electric heater, i.e. the heat source is all electric. In other examples, the heater may be part electric, e.g. part electric and part gas, or part electric and part other combustible fuel - a suitable combustible fuel may be natural gas, hydrogen gas, or propane gas or methane gas, or ethane gas, or butane gas, or a suitable combustible oil or woodchip or wood pellet or any combination thereof. In this way, some of the heating power is provided by the electric (DC and AC) component and some of it is provided by more traditional burnt fuel. This can help to add redundancy within the system, or can be used to operate efficiently in an environment where one or other power source is scarce. In some examples of this invention, the combined DC and AC power sources may be large enough to supply all or nearly all of the power output of a typical heater if required.

The features of the controller and the way in which power from the AC and DC sources is intelligently apportioned when powering the heating element that are described with reference to figures 1 and 2 can be used in combination with the later described embodiments and protection is specifically sought for any such combination(s).

Referring to figure 3, there is shown an electric space heater 100 similar to that described with reference to figure 1. Unless otherwise indicated, technical features are similar to those described with reference to any previously described embodiment (e.g. with reference to figure 1 or figure 2). The heater 100 is used to heat air in a standard domestic room space. Various aspects of the heater and heater system will be described in detail with reference to non-limiting examples. Other details will be apparent to the skilled person. In particular, aspects (including undescribed aspects) of known space heater systems can be incorporated and used with this invention by the skilled person.

In this example, the heater 100 is a convection heater and comprises a heater housing 102 to house its components.

In this example, the independent electric space heater 100 is a convection heater. In other examples, the heater may be a fan blower heater or an oil-filled radiator, or any other type of other electric space heater. The heater 100 comprises a heater housing 102 arranged to house its components. Often the heater of this invention will be required to be portable. In many examples, this invention includes features that make the heater compact to allow the heater to be easily carried and moved even though the inventive heater comprises new components (as will be described in more detail below).

The heater 31 is arranged to heat surrounding air. Relatively cold air arrives at the heater 100 (schematically illustrated by a virtual input pipe 104), is heated and then relatively hot air exits the heater 100 to the surrounding environment (illustrated by a virtual pipe 106). These virtual pipes are depicted in the drawings to help clearly describe the invention only; typically a convection space heater creates air currents in a space due to temperature differences between heated and unheated air (as previously described) - there are no physical pipelines in this embodiment.

The heater 101 comprises a first electric heating arrangement comprising a first electric heating element 108 and a case 110, which is located within the housing 102 between the input 104 and output 106, and arranged to contain the electric heating element 108. The case 110 electric heating arrangement is arranged to heat air passing through the heater and past the case 110. The case is a protective case to protect the exposed element 108 from wear and tear. In other examples the case may not be present; the heating arrangement is exposed.

As per this invention, the first electric heating element 108 is powered by a combined DC and AC power supply of the type described with reference to figure 1 ; in another example the combined DC and AC power supply may be of the type described with reference to figure 2, or related examples. For clarity, most of the common components shown in figure 1 are not replicated in figure 3 (e.g. the controller and its related circuitry).

In some embodiments, the electric heating arrangement may comprise multiple electric heating elements. In embodiments in which the electric heating arrangement comprises multiple electric heating elements, some may be arranged to be powered by AC only and some may be arranged to be powered by DC only and some may be arranged to be powered by both AC and DC. Any combination of these options is possible, as will be apparent to the skilled person.

In this example the DC power supply is in the form of a battery pack 120, which is also located within the housing 102. In this example, the heater is a fully electric heater, i.e. the heat source is all electric. In other examples, the heater may be part electric, e.g. part electric and part gas, or part electric and part other combustible fuel - a suitable combustible fuel may be natural gas, hydrogen gas, or propane gas or methane gas, or ethane gas, or butane gas, or a suitable combustible oil or combustible solid or mulch or any combination thereof. In this way, some of the heating power is provided by the electric DC component and some of it is provided by more traditional burnt fuel. This can help to add redundancy within the system, or can be used to operate efficiently in an environment where one or other power source is scarce. In some examples of this invention, the DC power source is large enough to supply all or nearly all of the power output of a typical heater if required.

In this example, the DC power supply has a capacity of 0.25kWh.

In general, the DC power supply capacity may be arranged to significantly increase maximum performance of the space heater and/or allow the space heater to run on the DC supply with at least a reasonably useful power outer for a reasonably useful amount of time. Some example configurations include:

• 2kW to 3kW convection heater with up to 1500W AC and up to 1500W DC. A range of models in that capability may include a: 500Wh battery, 750Wh battery, or a IkWh battery. As an illustration, 500Wh can be used to provide IkW AC and IkW DC for half an hour etc.

• 2kW to 4kW Oil filled radiator - similar set up and batteries from 750Wh up to 2kWh or more.

Fan heater - including DC batteries capable of running 250Wh at 1.5kW for max 10 mins. These can be added to the AC heat of 1.5kW to give a total of 3kW. A powerful space heater of this invention may provide at least 400Wh and have a 5kW to 6kW combined (AC+DC) peak output. In this embodiment, the battery pack 120 comprises a stack of batteries in a compact configuration.

In this example, the 0.25kWh DC battery pack 120 comprises 25 replaceable or rechargeable cylindrical cells, such as standard sized 18650 cells (18 mm diameter and 65mm length), each having a capacity of about 10 Wh. In this example, the rechargeable cells are arranged in a 5x5 stack for compactness and the entire stack can be removed from the battery pack 120 and recharged externally from the housing 102. In another example, the stack may be a different configuration - other suitable stack configurations will be apparent depending on the available space for the battery pack. The stack is configured to provide substantially consistent use over time of each cell within the stack in a known manner so that the stack operates effectively as a single unit. In some examples, the DC power source can be charged from renewable heat sources too, such as solar or wind or a heat pump or any other suitable source.

In other embodiments, the DC battery pack can be charged in situ, i.e. without removing any cells from the housing 102, via a charging connection (not shown).

In some examples, such as this one, the space the DC power supply is configured to be simultaneously chargeable and to power the electric heating arrangement. The DC power supply comprises a battery pack having multiple cells. The controller is arranged to simultaneously: use some cells of the DC power supply for heating the electric heating arrangement; and charge some (or all) other cells of the DC power supply.

Charging of the battery pack is carried out in this example by an AC to DC converter (not shown), and in examples where the charging is carried out in situ, the heater further comprises an AC to DC converter located within its housing.

A typical 18650 cell has a voltage of 3.6V. In this example, the cells in the pack 120 are arranged in series, i.e. the effective voltage is about 90V. The pack is well insulated. In other examples, the cells may be arranged differently, e.g. all in series (so that the maximum voltage in any single path is 3.6V) or in parallel paths having a few cells in series, e.g. 5 parallel paths, each having 5 cells (18V) in series.

In some embodiments, cells can be arranged to provide substantially the same voltage as an AC input supply voltage - this makes combining AC and DC easier, and makes charging easier too. E.g. in the UK, a 240V battery pack may be provided. In some embodiments, instead of a single battery pack, multiple battery packs or stacks within a battery pack are provided.

In some examples, the DC power pack capacity is at least 50Wh, or optionally lOOWh. Therefore, in a 400W heater, AC can be supported for 15 mins with lOOWh. Or, double that power for 15 mins. Maximum capacity of no real limit - industrial independent heaters of this invention may have large batteries. In some cases, the DC power supply is arranged to have an output power capability of at least 200W; in other cases, at least 400W. This invention provides a significant power boost compared to using an AC -only electric heater, e.g. a 50Wh DC power pack used with this invention allows an additional 500W operation for 6 minutes (e.g. a total output of 3490W in UK or 2900W in US from a standard power socket (which is otherwise limited as previously discussed)). Larger capacity power packs would offer even greater running time in combination with greater boosted power levels.

The heater 100 housing also uses its AC connection 130 in order to power small electronic components (these have a relatively low power demand compared to the power required to heat air during normal heater operation) such as the controller, adapter(s), switching circuitry, heater display screen, heater user interface, sensors, Wi-Fi, Bluetooth, sub 1GHz comes etc, led lighting and other standard space heater components. Other such components may include: (thermal switch - sometimes stated separately to temperature sensors by manufacturers); thermostat; thermocouple / PRT; control PCB; multi-media interface; power electronics for powerpacks; fans (simple electrical or possibly more complex with drive electronics). In some examples, this power may be provided by renewable heat sources too, such as solar or wind or a heat pump or any other suitable source. In some other examples, any one or combination of these small electronic components can be powered directly from the DC power supply.

In this example, the heater 100 also comprises the controller (not shown) arranged to control any one or more of: heating, battery charging, battery discharging, system requirements, switching of the DC power supply as described with reference to the example of figure 1.

The battery of this invention produces some heat. Other electrical components of the heater also produce some heat. The inventors have realised that a compact, efficient non-standard cooling system is required.

The heater 100 of this embodiment also comprises a cooling system (not shown). The electronics (controller, switches, adapters etc.) can get hotter than on a normal heater because of the DC battery power involved and extra switching because of intelligent use of a DC battery, and operation of the controller and its related circuitry due to wanting to use DC-v-AC intelligently.

In some examples, the heater comprises a high-power switching module arranged to efficiently switch high currents such that power can be varied in the same resistant electric heating element. This is especially important in the mode in which AC and DC are combined to provide a quickly switched output that uses less average AC power, but maintains a steady overall total combined power output for the heater. This feature allows pulse width modulation within the control circuitry. The high-power switching module may be arranged to switch 3, 5, 13, 15, 20 amps or more (e.g. 30 amps or even more).

In examples containing a battery charging mechanism, the inventor further found that heat generation within the battery charging system can be a problem - specifically in an AC-DC converter battery charging system, which allows a voltage to charge the DC battery packs/cells. This type of battery charging system does not exist within any electric space heater systems or heater housings yet, and generates heat. A further advantage of some examples of the present invention is therefore to use the cooling system (or to provide a further separate cooling system) as a heat sink to cool the battery charging mechanism too. The battery charging mechanism cooling system can be particularly useful since charging can (and should) also occur when the heating system is not on (i.e. when it is not heating a space, e.g., in the middle of the night, or when it is detected that a user has left the space (such as if a sensor senses that a person has left a room that is being heated)). The present invention’s cooling system allows for running the heating system to leach heat away during charging-only periods. The controller may be arranged to force cold air through the heater (e.g. by operating a fan) to cool the battery charging mechanism even when heated is not required, e.g., the controller may act in response to predicting or being informed or sensing that the battery charging system should be cooled (e.g., via feedback from a temperature sensor located near the battery charger or after the battery has been continuously charging for a threshold minimum time period). This battery charging mechanism cooling feature can be implemented with any of the described embodiments containing a battery charger to create a new embodiment of the invention. In some examples (e.g., in which flow of the ambient air is participating in the cooling), when the heating system is running (e.g., heated air is being demanded), then cooling occurs via flow of the cool air to be heated past any one, some, or optionally all of, the controller I battery / battery charger / adapter(s) / any other control electronics. However, when the heating system is not running, this invention allows for operation of the charger cooling system (whether via flow of the ambient air or via its own dedicated coolant within its own dedicated coolant circuit) specifically for the purpose of cooling the battery charger. This feature may be particularly useful in examples of the invention which have a high powered charging system (which may be the case for larger batteries or smaller batteries which can be charged quickly or any combination of these).

In some examples, the cooling system uses some of the cool air, which arrives at the cold input 104 for cooling the electronics, which may be much hotter (ideally, the intention is to keep the electronic components well below 100 degC). In some examples, an element of the cooling system comprises locating the cool air intake from the input 104 within the heater 100 adjacent or near to the components that require cooling. As a result, overall efficiency of the heater is enhanced and its electronics can be made more compact / simpler due to a reduced need for perfect electronic efficiency with switching power.

The cooling system of some examples includes a coolant circuit having a closed coolant pipe system (not shown) through which coolant is pumped. The closed coolant pipe system is configured to encourage heat transfer between the coolant and the heater’s cool air input so as to transfer heat away thereto as well as to encourage heat transfer between the coolant and the battery cells or other components so as to transfer heat away therefrom. This is achieved by routing the pipe system close to any one or more of the heater components, battery cells and cool air input at appropriate locations.

In many embodiments, the DC power supply cells and the electronic components are protected from the heat of the electric heating arrangement. In some examples, the electric heating arrangement is located above the DC power supply cells and/or the electronic components to protect them (from rising hot air). In other examples, the DC power supply cells and/or the electronic components may be located to the side of the heating element(s). In some examples, the DC supply and/or the sensitive components may be located above the heating elements; in such examples, heat from the heating elements may be deflected around the cells/pcb etc., e.g. via one or more physical deflector panels, possibly heat-reflective deflector panels. Also, the housing protects direct infrared heat from the heating elements just by being a barrier to direct line of sight; so, in some examples, the DC power supply and/or other sensitive elements are located in compartmentalised parts of the housing that are separated from the heating element(s) appropriately.

In some examples, the housing 100 comprises an access door arranged to allow access to internal components of the heater (such as for servicing or repair) and the DC power supply is arranged within or integrally with the access door. This also adds to the overall compactness and also ensures that the DC battery does not need to be further removed or manipulated to access the internal heater components (e.g. for repair / servicing).

In this example, the heater 100 also comprises a thermal break or heat shield (not shown) located between the DC power supply and the first heating arrangement; and also between the controller and the first heating arrangement. The thermal break or heat shield may comprise any one or any combination of: an air gap; a gap filled (partly or fully) by a thermal insulation material; a gap filled (partly or fully) by an infrared-reflective material; a gap filled (partly or fully) by an insulator or low thermal conductivity material.

In some examples, the heat shield may include an associated heat shield cooling mechanism arranged to transfer heat from the heat shield area towards another area in which it is safer to dissipate heat and comprising any one or more of:

• a fluid material, e.g. air or water, that takes heat away from the area (e.g., from the heat shield area to a dissipation area (i.e. another area in which it is safer to dissipate heat than in the heat shield area));

• an active cooling mechanism, such as a Peltier device (that actively moves heat from one side to the other, e.g. towards another area in which it is safer to dissipate heat than in the heat shield area);

• a chilled cabinet or block located inside the heater (similar to a typical refrigerator) and arranged to substantially enclose the DC power supply; and

• an air flow mechanism, such as a blower, arranged to draw air in from outside the housing, or from inside the housing, to provide the required cooling effect. In a further embodiment (not shown), the heater comprises a hybrid electric-gas heater case instead of a case with only an electric heating element. In such an embodiment, within the same sealed, heater case chamber are provided multiple heating mechanisms. One is an electric heating mechanism (similar to that described in relation to other embodiments); the other is a gas burner mechanism. The gas burner mechanism is of a known type. Instead of natural gas, the other mechanism might be a different fuel combustion burner (e.g. hydrogen gas, propane gas, oil). The electric heating mechanism can be in any suitable form. In this example, it is in the form of electric heating elements. The heater may be arranged in one example to heat air in a space. The electrical heating element or multiple such elements can be located anywhere in or around the burner case such that air can be heated by either or both of the gas and the electric heating mechanisms. The heating elements can be electrical wires that can be heated by passing electric current therethrough and arranged suitably to deliver heat where needed. (E.g. wrapped around a pipe or any other component within the burner case). In some examples, the electric power supply is arranged to provide pre-heating when the hybrid heater is first turned on, and when the combustible fuel alone requires assistance in bringing a space up to a desired temperature. In some cases, this is because the combustible fluid may be heating up via a heating block (or similar), which takes time (e.g. minutes) to warm up from cold.

There may be a heat exchanger within the gas burner case. The heat exchanger is arranged to focus heat from the burning gas, the heated electric element(s), or both to the air to be heater. The heat exchanger may be metal or ceramic. In one example, the heat exchanger may be in the form of one or more plates (e.g. metal plates) arranged in proximity to the air to be heated. Electric heating elements can be arranged between the plates. In another example, there may be a block of suitable material (e.g. a ceramic block) arranged near the air to be heated.

More specific examples of the invention will now be described with reference to schematic drawings that show some key elements of these examples. Other elements of the examples may not be shown or described, but will be apparent to the skilled reader. In particular, all of the examples can work with any of the above-described features (e.g. in relation to figures 1, 2 or 3), and all such combinations are disclosed by virtue of this description. E.g. tip- or fall- sensing with automatic shutoff; the various controller control factor options; different battery capacity options; different power supply-balancing AC-v-DC options.

In some of these examples, the DC + AC power supply combination is arranged to increase peak power of the electric heating arrangement relative to using AC only by at least 25%; in other examples, by at least 50%, and in other examples by at least 100% (i.e. doubling the output, if about 100%); in yet further examples, by significantly more than 100%.

Example 1: Fan blower (figures 4a to 4d)

The electric space heater comprises a fan blower space heater 400 arranged to heat a space such as a room. The heater has a housing 402, which includes a foot 440 arranged to provide a broad and stable support for resting the heater on a flat surface. The housing has an air intake aperture 404 through which air from the space can enter the housing, and air output aperture 406 through which heated air can leave the housing to enter the space.

The heater comprises a first electric heating arrangement comprising a coiled electric heating element 408 arranged to heat air that flows through or past its coils. The heater comprises a fan 480 arranged to blow the air heated by the heating element 408 into the space to be heated. In this example (may be different in other examples), both the coiled heating element and the fan are coaxially mounted relative to the housing such that they are aligned in a straight line with the intake 404 and output 406 apertures. Therefore, the fan is also arranged to pull in air to be heated from the space towards the electric heating element.

The heating element 408 can be of any type previously described and is arranged to be powered by a mains AC power supply or a DC power supply as previously described in relation to other examples.

The heater also comprises power electronics 424, including a controller, which is arranged to control distribution of power to the heating element from the DC power supply and the AC power supply in a similar manner to that described above in relation to earlier embodiments. The power electronics 424 also includes an AC supply interface arranged to interface with the mains AC power supply. The power electronics is located below the first electric heating arrangement so that undesirable heating effects on the power electronics from the heating arrangement are mitigated. In this example, the heater comprises the DC power supply, which is in the form of a battery pack 420 comprising an array of easy-to-access, rechargeable cells. The battery pack is located below the first electric heating arrangement so that undesirable heating effects on the battery pack from the heating arrangement are mitigated.

In this example, peak power is 400W. In other examples, it may be less, e.g. for a smaller car cabin heater version. In other examples, it may be more, e.g. upto 3kW for domestic examples, and over lOkW for industrial fan blower heaters. Typical peak powers for space heaters according to this invention will be in the range 1500W-2000W. Such space heaters often have multiple heat settings, e.g. low and high settings may provide peak powers of IkW and 3kW respectively in one example.

The heater components and housing are configured to ensure that air flow is separated from the cells and electronics as will be described in more detail. Physically the heat is always above the cells and electronics to protect them (hot air rises etc).

The housing 402 is a compartmentalised housing 402 having two chambers, a first upper chamber containing the heating element 408 and the fan 480, and a second lower chamber containing the battery pack 420 and the power electronics (including controller and AC supply interface) 424. In this example, the upper chamber is directly above the lower chamber. Each chamber is relatively closed. In this example, the housing comprises a separating wall 403 between the upper and lower chambers - the wall 403 is arranged to protect the battery pack and control electronics from direct infrared heat from the heating elements by being a barrier to direct line of sight. The first chamber being above the second chamber, in use, also ensures that convective heat from the heating element 408 does not undesirably affect the battery pack and control electronics 424. Further, since the fan, the electric heating element and the air inlet to and air outlet from the heater housing are aligned in their own chamber, air is guided in a desired path that does not naturally flow past the second chamber (i.e. does not affect the battery or controller electronics).

Example 2: Fan blower (figures 5a to 5e and 6a to 6e)

The electric space heater comprises a modular fan blower space heater 500 arranged to heat a space such as a room. For clarity, figures 5a to 5e show the space heater with its modules separated, and figures 6a to 6e show the space heater with its modules assembled in one working configuration. Note that it is also possible to assemble the modular space heater in a different working configuration as will be explained in more detail below.

The housing has an air intake aperture 504 through which air from the space can enter the housing, and air output aperture 506 through which heated air can leave the housing to enter the space.

The heater comprises a first electric heating arrangement comprising a coiled electric heating element 508 arranged to heat air that flows through or past its coils. The heater comprises a fan 580 arranged to blow the air heated by the heating element 508 into the space to be heated. In this example (may be different in other examples), both the coiled heating element and the fan are coaxially mounted relative to the housing such that they are aligned in a straight line with the intake 504 and output 506 apertures. Therefore, the fan is also arranged to pull in air to be heated from the space towards the electric heating element.

The heating element 508 can be of any type previously described and is arranged to be powered by a mains AC power supply or a DC power supply as previously described in relation to other examples.

The heater also comprises power electronics 524, including a controller, which is arranged to control distribution of power to the heating element from the DC power supply and the AC power supply in a similar manner to that described above in relation to earlier embodiments. The power electronics 524 also includes an AC supply interface arranged to interface with the mains AC power supply. The power electronics is located below the first electric heating arrangement so that undesirable heating effects on the power electronics from the heating arrangement are mitigated.

In this example, the heater comprises the DC power supply, which is in the form of a battery pack 520 comprising an array of easy-to-access, rechargeable cells. The battery pack is located below the first electric heating arrangement so that undesirable heating effects on the battery pack from the heating arrangement are mitigated.

In this example, the invention provides a 500Wh fan heater - peak output 2.5kW from DC with a 2.5kW max AC heat system. This allows for a total output of 5kW. However, the heater can be controlled by the controller to operate in a low power mode providing 250W AC and 250W DC, and the battery pack would then last for a long time, around 2 hours. The heater 500 has a modular housing comprising three modules: a base module 502a arranged to house the power electronics 524 and to interface with the AC power supply and having the intake aperture 504 formed therethrough; a mid-section module 502b arranged to house the DC power supply 520 and a top module 502c arranged to house the electric heating element 508 and the fan 580 and having the output aperture 506 formed therethrough. The base module, mid-section module and top module are arranged to slot together to form multiple working configurations of the heater housing as will be described below. In other examples, the modules may join together by any suitable mechanism, including one or more of slot fitting; clip fitting; friction fitting; screw fitting; bolt fitting.

In this example, the base module 502a includes a pedestal 540 configured to raise the bottom of the heater such that the air intake aperture can be and is formed in the bottom, in-use downwardly-facing surface, of the base module 502a. The air intake is thereby raised from a surface on which the space heater rests whilst being formed through the heater’s bottom surface. The air intake, the DC power supply, the heating element, the fan and the air output are thereby aligned providing for an efficient desired air flow path.

The pedestal also provides a broad and stable support for resting the base module on a flat surface.

In this example, a grill 550 is provided at the air output aperture to enhance safe operation (to prevent large objects / fingers from reaching the heating element and fan), Whilst allowing heated air to move freely away from the heater.

In this example, the housing is a generally cylindrical housing, and each module of the housing is correspondingly profiled to provide a smooth outer profile and pleasing aesthetic appearance, while allowing for efficient operation. The housing is elongate (to allow desired alignment of components as discussed above).

Advantageously, multiple working configurations of the modular heater are possible. The base module is connectable directly to the top module, and also direcdy to the mid-section module. The top module is connectable directly to the top module, and also directly to the mid-section module. The mid-section module is connectable to the base module and the top module.

In a first working configuration (as seen in figures 6a to 6e), all three modules can be used together to provide heating via the AC and DC power supplies.

In a second working configuration (not shown in the drawings), the base and top modules can be used together, without the mid-section module, to provide heating via the AC power supply only.

The controller 524 is configured to recognise (e.g. via a suitable sensing mechanism) which modules are connected into which working configuration. Based on this recognition, the controller can control power supply (AC only or an intelligent combination of AC+DC) to the electric heating element accordingly.

Battery cells can be charged without removing the pack from the mid-section module. The heater can run without the mid-section module in the second configuration, e.g. while the battery pack is recharging.

Advantageously, in the first working configuration, the battery pack and control electronics are located upstream of the heating element in the air flow path that is defined by the fan. Therefore, in use, relatively cool air flows past both the battery pack and control electronics, and is used to cool them (as they can generate undesired heat during operation). Via this arrangement, the air to be heated also receives some pre-heating before reaching the heating element, which makes the overall heating process more efficient.

Similarly, in the second working configuration, the control electronics are located upstream of the heating element in the air flow path that is defined by the fan, and similar advantages result.

In this example, there is therefore no other cooling system necessary. In other examples, the invention provides another cooling system, e.g. a separate cooling system for the electronics (one or more of the controller, adapters, battery charger) and for the battery pack.

As in other examples, physically the heat is above the cells and electronics to protect them (hot air rises etc).

The combined housing 502a, 502b, 502c of this modular, portable fan heater example is about 20cm in diameter, and 35 cm in height. Other size and shape options will be apparent to the skilled reader.

Example 3: Convection heater (figures 7a to 7e)

The electric space heater comprises a convection space heater 700 arranged to heat a space such as a room. The heater has a housing 702, which includes a bracket 740 arranged to facilitate safe mounting of the convection heater to a wall in a known manner. The housing has a series of apertures along its lower surface which serve as air intake apertures 704 through which air from the space can enter the housing, and a series of apertures along its upper surface which serve as air output apertures 706 through which heated air can leave the housing to enter the space. As previously discussed, air is heated by the convection heater, the air rises and is replaced by cooler air from the space, creating a current of warm air that circulates throughout the space. This occurs via the apertures 704, 706.

The heater comprises a first electric heating arrangement comprising two nichrome electric heating elements 708 arranged to heat air that flows through or past them. The heater does not comprise a fan in this example; natural convection drives air flow of the air heated by the heating elements 708 into the space to be heated.

The heating elements 708 can be of any type previously described and are arranged to be powered by a mains AC power supply or a DC power supply as previously described in relation to other examples.

The heater also comprises power electronics 724, including a controller, which is arranged to control distribution of power to the heating elements from the DC power supply and the AC power supply in a similar manner to that described above in relation to earlier embodiments. The power electronics 724 also includes an AC supply interface arranged to interface with the mains AC power supply. The power electronics is located below the electric heating arrangement so that undesirable heating effects on the power electronics from the heating arrangement are mitigated.

In this example, the heater comprises the DC power supply, which is in the form of a battery pack 720 comprising five blocks of rechargeable cells. The battery pack is located below the first electric heating arrangement so that undesirable heating effects on the battery pack from the heating arrangement are mitigated. In this example, the controller includes a battery charging mechanism and the battery pack is arranged to be charged in situ via the power electronics.

In this example, the convection heater is suitable for domestic use and its peak power is IkW. In other domestic use convection heater examples, the peak power may be 500W to 3kW.

The housing 702 is a compartmentalised housing 702 having two chambers, a first upper chamber containing the heating elements 708, and a second lower chamber containing the battery pack 720 and the power electronics (including controller and AC supply interface) 724. In this example, the upper chamber is directly above the lower chamber. Each chamber is relatively closed. In this example, the housing comprises a separating wall 703 between the upper and lower chambers - the wall 703 is arranged to protect the battery pack and control electronics from direct infrared heat from the heating elements by being a barrier to direct line of sight. The first chamber being above the second chamber, in use, also ensures that convective heat from the heating elements 708 does not undesirably affect the battery pack and control electronics 724. Further, since the electric heating elements and the air inlet to and air outlet from the heater housing are aligned in their own chamber, air is guided in a desired path that does not naturally flow past the second chamber (i.e. does not naturally affect the battery or controller electronics). In this example, notably the wall 703 does not seal off the upper and lower chambers from each other; an air flow path is left to allow air to travel freely from the intake to the output.

Furthermore, the convection heater has another heat shield 705 to shield the DC power supply, and the control electronics from heat from the electric heating elements. The heat shield allows air to flow past it, so that air can travel freely from the intake to the output. In this example (see figure 7e), the heat shield comprises a cross plate below the electric heating elements and above the battery and control electronics. The cross plate does not abut the interior walls of the heater housing such that some air is allowed to flow past the cross plates. In other examples, the cross plates may instead or additionally have apertures formed therethrough to allow air to flow past. In this example, the two heat shield plates 703, 705 work well together: the upper heat shield 703 may become warm enough to radiate heat, and the lower, secondary heat shield 705 is arranged to shield the battery and other components in the lower chamber from the heat radiated from the upper heat shield. Alternative configurations of heat shield (e.g. not plates) will be apparent to the skilled person.

In other examples (not shown), the convection heater may, instead or additionally, have a thermal break or heat shield or both between the battery (and/or power electronics components) and the housing 702 (which might undesirably conduct heat from the heating area (near the heating element(s)) towards the battery and/or power electronics. The same type of thermal break (e.g. an air gap) or heat shield as described previously in relation to other examples can be used. The thermal break may comprise the housing itself having a built-in break (e.g. a strip of insulating material (such as ABS plastic or nylon) between sections of the housing (e.g. metallic sections) - in such cases, metal housing enclosing the heating element(s) may become and remain hotter than metal housing enclosing the battery, e.g. the housing around the upper chamber may be much hotter than the housing around the lower chamber. 8a to 8d)

The electric space heater comprises an oil-filled radiator space heater 800 arranged to heat a space such as a room. As previously discussed, air is heated by the radiator heater radiating heat outwards, warming the surrounding air. In figure 8a, arrows 804, 806 are shown to depict this process.

The heater has a two-part housing, Part one of the housing is a radiator housing 802a, which contains: a first electric heating arrangement 808; and a heating fluid, in this case, oil. Part two of the housing is an electrical component housing 802b, which contains a battery pack 820 and power electronics 824. These features are described in further below. The radiator housing has metal fins as shown in the drawings. The housing also includes feet 840 that are arranged to provide a stable support for resting the heater on a flat surface in a known manner.

The heater comprises the first electric heating arrangement, which comprise an electric heating bar 808 arranged to heat oil that flows past it within the radiator housing 802a. The heater does not comprise a fan in this example; the metal fins of the radiator housing heat up due to the hot oil inside and radiate heat out into the space to be heated. In use, oil at the top of the radiator is warmer than oil at the bottom (hot fluid rises). After the oil has lost heat to the surroundings via the fins, it sinks to the bottom. The electric heating bar 808 is located near the bottom of the housing 802a. The cold oil is heated, rises, and the process repeats.

The heating element 808 can be of any type previously described and is arranged to be powered by a mains AC power supply or a DC power supply as previously described in relation to other examples.

The heater also comprises power electronics 824, including a controller, which is arranged to control distribution of power to the heating elements from the DC power supply and the AC power supply in a similar manner to that described above in relation to earlier embodiments. The power electronics 824 also includes an AC supply interface arranged to interface with the mains AC power supply. The power electronics is located to the side of the electric heating arrangement in a separate part of the housing, the electrical component housing 802b, so that undesirable heating effects on the power electronics from the heating arrangement are mitigated.

In this example, the DC power supply is in the form of a battery pack comprising six easy-to-access, modules, each module comprising a block of cells that are in electrical series communication with each other. The battery modules are arranged in a 3x2 configuration in this example for compactness. Each module can be easily removed for charging.

The battery pack is located to the side of the electric heating arrangement in a separate part of the housing, the electrical component housing 802b, so that undesirable heating effects on the battery pack from the heating arrangement are mitigated.

Notably, the two parts of the housing 802a, 802b are arranged to securely connect together in use such that the contents of the electrical component housing 802b are heat shielded from the contents of the radiator housing 802a. Further the two parts of the housing 802a, 802b are arranged to securely connect together in use such that the power electronics 824 is located close to the electric heating arrangement so that the amount of wiring required between the two is minimised - advantageous for assembly and reducing wire routes etc.

The two parts of the housing 802a, 802b can be easily separated when needed, e.g. the electrical component housing 802b can be easily removed to allow access to the batteries and power electronics for charging or replacement / repair.

In some examples, the controller includes a battery charging mechanism and the battery pack is arranged to be charged in situ via the power electronics.

In this example, the heater 800 is suitable for domestic use and its peak power is IkW. In other domestic use examples, the peak power may be 800W to 2.5kW.

Example 5: Oil-filled radiator (figures 9a to 9d) In this example, the space heater comprises an oil-filled radiator 900 similar to that of example 4. For clarity, similar features will not be repeated. The radiator 900 differs from the radiator 800 in that its battery 920 and power electronics 924 are located in an electrical component housing 902b underneath its radiator housing 902a. Instead of feet, the radiator is supported by four wheels 940 arranged to stably support on flat ground and for ease of portability.

Example 6: infra-red radiative space heater (not shown in drawings)

Infra-red radiative space heaters are within the scope of this invention. The skilled reader will understand that such a heater will work on similar principles to those previously described, and may have a peak power of 300W, in one example. Other examples might have a peak power of at least IkW, perhaps 3kW.

Example 7: all-electric patio space heater (not shown in drawings)

All-electric patio space heaters are within the scope of this invention. The skilled reader will understand that such a heater will work on similar principles to those previously described, and may have a peak power of 1500W, in one example. Other examples might have a peak power of at least 5kW, perhaps lOkW.

Example 8: hybrid gas-electric electric patio heater space heater (not shown in drawings)

Hybrid gas-electric electric patio space heaters are within the scope of this invention. The skilled reader will understand that such a heater will work on similar principles to those previously described, and may have a peak power of 1000W, in one example. Other examples might have a peak power of at least 3kW, perhaps 7kW.

Example 9: hybrid combustible fuel-electric spot space heater (not shown in drawings)

Hybrid combustible fuel-electric spot space heaters are within the scope of this invention. The skilled reader will understand that such a heater will work on similar principles to those previously described, and may have a peak power of 500W, in one example. Other examples might have a peak power of at least 2kW, perhaps 5kW.

Various modifications may be made to this invention without departing from its scope.

Optionally, in some examples where the heater comprises two (or more) heating elements, the controller may be arranged to power a first heating element only via the DC power supply and a second heating element only via the AC power supply. This feature reduces the need for more complex circuitry and therefore reduces the risk of circuitry failure. Further, if one source fails, the other still works.

In other examples, the heater comprises an industrial sized furnace air heater (similar to the above-described portable space heater but larger).

In any of the examples, AC could be disconnected (or unavailable, e.g. during a power cut) and the heater could be run only from the DC power supply.

In some examples, the DC battery capacity may be at least 0.1 kWh power supply, e.g. about 0.2kWh or about 0.5kWh or about IkWh. Peak power output may be about 3kW DC and 3kW AC combined in some examples.

More than one heating element may be provided per heater case.

For any embodiment described as solely electric, the skilled person will appreciate that it may alternatively be provided in a part electric -part combustible fuel format.

Any of the examples may include a DC power supply interface arranged to receive the DC power supply, wherein the DC power supply interface is configured to receive more than one type of DC power supply, such as any combination of an Ni-MH battery cell pack, an Ni-Cd battery cell pack and a lithium battery cell pack or a mixed pack containing a mixture of any of these types of cells. Supercapacitors can be used instead of or in addition to a traditional DC battery pack to provide the DC power source.

Any of the examples that include DC power supply cells may include a safety shut-off mechanism arranged to disconnect the cells from powering the electric heating element. The safety shut-off mechanism may comprise a master switch or automatic master switch; in some examples the safety shut-off mechanism comprises a contactor. Advantageously, a safe, simple DC switching mechanism is thereby provided. In particular, for floor-standing or portable space heaters, the safety mechanism is triggered if it is detected that the heater has tipped over or has been lifted from a flat or stable surface. The space heater may one or more feet arranged to rest stably on a flat surface. Such a safety mechanism (fall sensing mechanism) is particularly important for this invention because, if the heater is knocked over, heat could leach to battery cells posing a more significant hazard than for a traditional space heater.

Electric heating element(s), or a battery, or both, along with a control mechanism (e.g. control electronics and/or software) to control the amount of heating provided by DC, AC or a combination thereof can be retro-fitted to an existing electric space, gas (or other combustible fuel) or gas-electric hybrid heater to provide a heater within the scope of this invention.

The inventive space heater may be more powerful and more efficient as previously described. Such examples may be particular suitable for retro-fitting electrical heating capability to existing AC electric heaters or gas heaters. For example, electric heating elements may be coated on, coated within, sprayed, contained in, wrapped around, partially or totally embedded in, or otherwise associated with, a duct section at or near: its exit from a combustible fuel burner case: its entrance to the burner case; or both. The heating element(s) may be powered by DC, AC or a combination thereof. In some examples, a battery, such as a large battery of the type previously described, may be attached to the burner case along with a control mechanism (e.g. control electronics and/or software) to control the amount of heating provided by the electric heating element(s) compared to the combustible fuel source. When attached to an AC electric heater, a DC power pack may be added along with suitable control electronics to allow a balanced use of DC and AC depending on demand requirements and / or supply.

In any, all or some embodiments, there is provided a battery charging mechanism, which is arranged to charge the DC power supply taking into account, and in response to, any one or more of: current DC power supply battery charge level; capacity of the or each power supply; instantaneous demand for heating; forecasted demand for heating; instantaneous or forecasted available supply type; and household demand, local demand, national demand, international demand or any combination thereof. Typically, the battery pack is charged at low demand times, e.g. in the middle of the night or middle of the day (when the controller is told that AC demand (not necessarily just from heating) is usually low, or the controller learns that grid electricity demand is low, in some cases).

In any of the described examples, the, any or each heating element may be any element that emits heat when an electric current is passed therethrough, such as any resistive wire, or arrangement of wires, that emits heat when a current is passed therethrough, such as (but not limited to):

Thin film (polyimide over conductive metal);

Ceramic (ceramic sheath with embedded nickel chrome aluminium etc.) wire;

Bare wire (nickel, nichrome, Kanthal, stellites etc. Tungsten);

Encapsulated wire - e.g. silicone jacketed nichrome;

Aluminium encased resistive element (e.g. die cast) with the resistive element arranged to be electrically isolated from the aluminium casing;

Mineral insulated wire - copper sheath / nichrome, cupronickel / Inconel, steel sheath / nickel, Inconel sheath / nickel allow wire and all sorts of mixtures of these. Elements may be drawn to size or manufactured at finish size etc. Insulation generally A12O3 or MgO;

Plain wires, spiralled (helical) wires, busbar wires with wound elements between.

Suitable alternative materials using similar arrangements will be apparent to the skilled reader.

In any example where a single heating element is described, it may be replaced by one or more different heating elements as will be apparent to the skilled reader. For example, one or more of the electric heating elements may comprise a conductive heating element coating on any one or more of: an interior surface of the heater; an exterior surface of the heater; or any other component. One or more of the electric heating elements may comprise an inductive heating element, e.g. such that it I they can be powered by induction (without direct contact).

In some cases, multiple distinct electric heating elements are arranged to heat air in distinct sections of the heater. In some examples, multiple distinct sections of heating element are provided within the heater, and each section may be controlled together or separately, e.g. to provide different levels of heating at different section locations. This is efficient in situations where different heating levels might be appropriate in different locations of the heater - it may be desirable to provide different heating levels at different sections of the air path, such as upon initial heating startup when air is first heated from cold, such as when heating is first demanded, more intense heating may be provided at the beginning of the air path than at the end because the initial input air is particularly cold. In some of these examples, the elements may be completely embedded in the heater housing such that no part of them emerges or protrudes from the duct (e.g. there is no external electrical connection point).

In some examples in which the heating element is to be provided in distinct zones (not continuously along the entire length of the heater housing), gaps between the distinct zones can be formed by masking gap sections of the housing surface (e.g. with a spray mask) during the coating / spraying process.

In some examples, the invention provides a single-housing space heater having an electric heating element arranged to be powered by both a large DC supply and an AC supply with an onboard controller and controller cooling system. The inventor realised that components of this type of system have significantly different cooling needs.

In some examples, the controller may be arranged to provide a power saver algorithm as follows: if DC power is unavailable (e.g., if the battery level is low or zero), then switch to powering the electric heating element via AC power only. The controller is programmed to ensure there is always some minimum threshold of DC capacity left, e.g., to allow a high-power heating start-up from cold, or AC-grid saving at very busy times, when it is really needed etc. This feature can be selectively activated or deactivated by a user via a user interface that sends instructions to the controller. In some examples, the minimum threshold of DC capacity may be 5% of total battery capacity to be held in reserve.

In some examples, the invention provides a space heater that achieves safe provision of modular power packs that are easily replaceable within the confines of the heater’s housing. The power packs are of a sufficient capacity such that the heating load for a typical domestic dwelling room space can be provided for via the DC power source for a reasonable time, e.g. for at least 5 minutes or at least 10 minutes. This size of power pack is located safely within the confines of the housing using a heat shield as previously described. Because the battery charger cooling mechanism may often be operated at different times to the controller and battery cooling mechanisms, it may comprise, or include a separate or distinct cooling mechanism to the controller and battery cooling mechanisms.

In some cases, there may be multiple cooling mechanisms, e.g. at least one cooling mechanism associated with the controller and/or other heater power electronics, at least one cooling mechanism associated with the battery and at least one cooling mechanism associated with the battery charger.

In some examples, the cooling system might be a passive cooling system (instead of or in addition to the previously- described cooling systems) arranged to transfer heat away from components to be cooled (such as the heater electronics or DC power supply or battery charger or any combination thereof). The passive cooling system may not comprise a flowing fluid. The passive cooling system may comprise a thermal heatsink (e.g. an aluminium block, with natural convection fins for heat dissipation into the environment. The passive cooling system may comprise a relatively large thermal mass, such as the heater housing.

Space heaters are generally portable, but can also be mounted to a surface such as a wall of a room. This is usually done by using appropriate mounting brackets. Depending upon the type of space heater, it is desirable to leave an air gap between a wall of the space heater and the surface to which it is mounted to allow safe flow of air.

In some examples, the heater comprises an AC port for providing power to other devices and/or USB ports or wireless charging for providing power to other devices.

In some examples, the heater may be arranged to work in a camping mode - it may be useful to run the fan version described above, or any other examples, as a portable camping tent heater.

In many examples, this invention can provide a significant power boost compared to using an AC-only electric heater, e.g. a 50Wh DC power pack used with this invention allows an additional 500W operation for 6 minutes (e.g. a total output of 3490W in UK or 2900W in US from a standard power socket (which is otherwise limited as previously discussed)). Larger capacity power packs would offer even greater running time in combination with greater boosted power levels.

In some examples, any one or more of: the controller; the AC power supply adapter; the DC-AC converter; and the AC-DC converter is located near (e.g. within 50cm, or within 15cm, or within 10cm, or within 2cm) to the first electric heating arrangement. This reduces the amount of wiring needed and simplifies assembly. It also reduces the potential for electrical interference and so provides more efficient operation.

In any example, the space heater’s controller may comprise a hardware thermostatic controller and optionally a further graphical user interface thermostatic controller.

Claims

1. An electric space heater comprising: a first electric heating arrangement arranged to be powered by both an AC power supply and a DC power supply; and a controller arranged to control distribution of power to the first heating arrangement from the DC power supply and the AC power supply.

2. The space heater of claim 1 wherein the DC power supply has a capacity of at least 0.05 kWh, optionally at least 0.1 kWh, optionally at least 0.25 kWh.

3. The space heater of claim 1 or claim 2 wherein the AC power supply comprises a mains AC power supply, and the combined peak power of the DC power supply and the AC power supply is larger than the peak mains AC power alone by at least 25%, optionally by at least 50%, further optionally by at least 100%.

4. The space heater of any preceding claim further comprising the DC power supply, and optionally comprising a DC power supply charging mechanism arranged to recharge the DC power supply.

5. The space heater of any preceding claim further comprising a cooling system arranged to provide cooling to any one or more of: the controller; the DC power supply; and the DC power supply charging mechanism.

6. The space heater of any preceding claim wherein, in use, the first electric heating arrangement is located above the DC power supply, the controller and, optionally when dependent on claim 4, the DC power supply charging mechanism.

7. The space heater of any preceding claim comprising a thermal break or heat shield located between the DC power supply and the first electric heating element, and optionally between any one or more of: the controller; the DC power supply charging mechanism; or both the controller and the DC power supply charging mechanism; and the first electric heating element.

8. The space heater of any preceding claim wherein the AC power supply comprises an AC power supply adapter arranged to interface with an external AC power supply, such as a mains AC power supply.

9. The space heater of any preceding claim comprising: a DC-AC converter between the DC power supply and the first electric heating arrangement such that the first electric heating arrangement is arranged to receive only AC power from either the AC power supply, the DC power supply or both; or an AC-DC converter between the AC power supply and the first electric heating arrangement such that the first electric heating arrangement is arranged to receive only DC power from either the AC power supply, the DC power supply or both.

10. The space heater of any preceding claim wherein the controller is arranged to control combining of the outputs from the AC power supply and the DC power supply.

11. The space heater of any preceding claim wherein the controller is arranged to vary the proportion of AC to DC power to the first electric heating arrangement, optionally by controlling switching between AC-only and DC-only power supply modes.

12. The space heater of any preceding claim wherein the controller is arranged to: power the first electric heating arrangement using only the DC power supply when a heating boost is required and using only the AC power supply when steady, continuous heating is required; or power the first electric heating arrangement using the DC power supply when it is determined that a local AC grid may be overloaded; or both.

13. The space heater of any preceding claim wherein the first electric heating arrangement comprises a single electric heating element arranged to be powered by both an AC power supply and a DC power supply.

14. The space heater of any preceding claim wherein the first electric heating arrangement comprises multiple electric heating elements, such as a first electric heating element arranged to be powered by only the AC power supply and a second electric heating element arranged to be powered by only the DC power supply.

15. The space heater of any preceding claim further comprising a heater housing, wherein the heater housing is arranged to house the first electric heating arrangement, and optionally wherein the heater housing has an inlet through which atmospheric air enters the heater housing and an outlet through which heated air exits the heater housing, and further optionally wherein the inlet is in a bottom surface of the heater housing, the space heater further comprising a pedestal, optionally the pedestal being part of the heater housing, arranged to raise the inlet from a surface on which the space heater rests, in use.

16. The space heater of claim 15 further comprising guide means arranged to direct air along a desired flow path between the inlet and the outlet, and optionally wherein the guide means comprises a fan system, and further optionally wherein the fan system is arranged to direct air from outside the heater housing into the heater housing and to direct the air towards the DC power supply, the fan system further arranged to subsequently, after the air has passed the DC power supply, direct the air towards the first electric heating arrangement and subsequently towards the outlet.

17. The space heater of claim 15 or claim 16 wherein the heater housing is arranged to house any one or more of: the DC power supply; the controller; the cooling system; the DC power supply charging mechanism; the AC power supply adapter; the DC-AC converter; the AC-DC converter; and the fan system.

18. The space heater of any claims 15 to 17 comprising an elongate electric heater wherein the DC power supply, the controller, the first electric heating arrangement and the outlet are configured in a straight line, and optionally wherein the fan system is also configured in line with the DC power supply, the first electric heating arrangement and the outlet.

19. The space heater of any preceding claim comprising a modular space heater comprising a base module arranged to interface with the AC power supply, a mid-section module arranged to house the DC power supply and a top module arranged to house the first electric heating arrangement, the base module, mid-section module and top module being arranged to connect together via any one or more of: slot fitting; clip fitting; friction fitting; screw fitting; bolt fitting to form the heater housing.

20. The space heater of claim 19 wherein: the base module is arranged to connect directly to the top module, and also direcdy to the mid-section module; the top module is arranged to connect directly to the top module, and also directly to the mid-section module; and the mid-section module is arranged to connect to the base module and the top module; such that, in a first in-use configuration, all three modules can be used together to provide heating via the AC and DC power supplies, and in a second in-use configuration, the base and top modules can be used together without the mid-section module to provide heating via the AC power supply only.

21. The space heater of any preceding claim further comprising a radiator housing filled with heating fluid, such as oil, wherein the first electric heating arrangement is located inside and near the bottom, in use, of the radiator housing and is arranged to heat the heating fluid.

22. The space heater of claim 21 wherein the DC power supply is located below the first electric heating arrangement, in use.

23. The space heater of claim 21 or claim 22 wherein the DC power supply is located outside, optionally beneath or to the side of, the radiator housing, and optionally wherein the DC power supply comprises an attachable battery pack arranged to be attached to the radiator housing to form the space heater.

24. The space heater of any of claims 21 to 23 wherein the radiator housing is arranged to be attached to the heater housing, and optionally the radiator housing is located above the heater housing, in use.

25. A method of operating a space heater according to any preceding claim, the method comprising controlling the distribution of power to the first heating arrangement from the DC power supply and the AC power supply, and optionally solely by either the DC power supply or the AC power supply at any given moment.