Heater

Abstract

The heater (10) comprises at least one air inlet (14) and at least one air outlet (18). An airflow path is defined between the at least one air inlet and the at least one air outlet. The heater also includes an airflow generator configured to draw air through the air inlet and along the airflow path. A plurality of heater elements (42A, 42B, 44A, 44B) are positioned in series with respect to each other in the airflow path for heating air flowing along the airflow path. The heater further includes a control unit (58) configured to operate the plurality of heater elements in a first mode in which a first number of the plurality of heater elements is turned on, and in a second mode in which a second number of the plurality of heater elements is turned on, the second number being higher than the first number.

Description

Background Technology

[0001] Fan heaters generate warm air by creating airflow across a heater element. The heater element can be a positive temperature coefficient heater element. Summary of the Invention

[0002] According to a first aspect of the invention, a heater is provided, comprising: at least one air inlet and at least one air outlet, wherein an airflow path is defined between the at least one air inlet and the at least one air outlet; an airflow generator configured to draw air through the air inlet and along the airflow path; a plurality of heater elements positioned in the airflow path to heat air flowing along the airflow path, wherein the plurality of heater elements are positioned in series with respect to each other in the airflow path; and a control unit configured to operate the plurality of heater elements in a first mode and a second mode, wherein in the first mode a first number of the plurality of heater elements is turned on, and in the second mode a second number of the plurality of heater elements is turned on, the second number being greater than the first number.

[0003] A heater that generates airflow over its heating elements allows heated air to be directed to a specific part of a room or to a user. Using more than one heating element makes it possible to control the heater in different modes to produce low and high heating levels. By placing the heating elements in series in the airflow path, the same airflow is heated by each heating element. When more than one heating element is on, the air leaving the air outlet is heated more evenly. Additionally, by positioning the heating elements in series, the profile of the heating elements is relatively narrow. This allows the heating elements to be incorporated into physically constrained spaces.

[0004] Multiple heater elements can be two heater elements, and the first quantity can be one, and the second quantity can be two. By using two heater elements, the heater design can remain relatively simple, while still being able to achieve both high heating mode and low heating mode.

[0005] The first mode can be a low-power mode, and the second mode can be a high-power mode. Using at least two heating modes enables low-power operation. This reduces energy consumption when less heating is required.

[0006] Multiple heater elements can each have substantially similar rated power. For example, the rated power of each heater element can differ from the target rated power by 5% or less. Alternatively, multiple heater elements can each have the same rated power. By using multiple heater elements with similar or identical rated power, each heater element can have the same construction. This makes the device simpler and easier to manufacture.

[0007] Multiple heater elements may include a first heater element with a first rated power and a second heater element with a second rated power higher than the first rated power. Multiple heater elements may also include heater elements with different rated powers. This allows for a greater number of operating modes to be achieved for the same number of heater elements.

[0008] The first mode may include turning on the first heater element without turning on the second heater element, and the second mode includes turning on both the first and second heater elements; wherein the control unit is further configured to operate a plurality of heater elements in a third mode, wherein in the third mode, the second heater element is turned on when the first heater element is not turned on. The third mode may be a medium power mode. The medium power mode may include turning on one or more heater elements having a rated power between a low power mode and a high power mode. The first mode may include turning on only the first heater element, and the third mode may include turning on only the second heater element.

[0009] By using heater elements with different rated power, three power modes can be achieved using only two heater elements.

[0010] Multiple heater elements can be multiple positive temperature coefficient (PTC) heater elements. PTC heater elements are well-suited for airflow-based heaters. PTC heaters are highly efficient and heat up rapidly, thus improving the user experience. Alternatively, other types of heating elements can be used, such as wire-based heating elements.

[0011] The heater may also include a user interface configured to allow a user to select an operating mode from a range of user-selectable operating modes, including at least first and second modes.

[0012] The user interface can be configured to allow a user to switch the heater between at least a first mode and a second mode. The user interface may include at least one physical switch or other physical user interface to enable the user to control the heater. Alternatively, the user interface may include a wireless interface to enable the user to control the heater using a dedicated wireless control device or a mobile device such as a mobile phone. For example, the wireless interface may use WiFi™ or Bluetooth™ radio frequency protocols.

[0013] At least one physical switch may be multiple switches, configured to allow a user to switch multiple heater elements based on an operating mode.

[0014] The control unit may include multiple heater switches connected to the multiple heater elements and configured to turn the multiple heater elements on or off based on the operating mode. The multiple heater switches may be high-power MOSFETs or TRIACs.

[0015] At least one air outlet may include two air outlets, wherein a first airflow path is defined between one of the two outlets and at least one air inlet, and a second airflow path is defined between the other of the two outlets and at least one air inlet. By providing two air outlets, the heater can provide a wider heating zone than an equivalent single-outlet design. For example, this allows the heater to be used with an annular air duct assembly having heater elements on both sides of the heater, thus adapting the heater to use with a fan incorporating an air amplifier design. In some examples, the heater may include two air inlets, wherein airflow paths are formed between each air inlet and a corresponding air outlet.

[0016] The multiple heater elements may be a first heater element array positioned in a first airflow path, and the heater may further include a second heater element array positioned in a second airflow path for heating air flowing along the second airflow path. By providing two heater arrays, each heater array having multiple heater elements, each side of the heater can provide at least two heating levels. For example, when used with an annular air duct assembly, the first and second arrays may be positioned on the left and right sides, respectively.

[0017] The second heater element array includes multiple heater elements arranged in series in the second airflow path. By providing multiple heater elements in series, the airflow is heated more uniformly in the same manner as the first heater array.

[0018] The control unit is also configured to operate the second heater element array such that, in a first mode, a first number of the plurality of heater elements are turned on, and in a second mode, a second number of the plurality of heater elements are turned on. By controlling the heater elements of the second heater array in the same manner as the heater elements of the first heater array, the total output from the air outlet of the heater is more uniform.

[0019] Each of the first heater element array and the second heater element array includes a first heater element and a second heater element, and the control unit includes a first switch arrangement connected to the first heater element of the first heater element array and the second heater element array, and a second switch arrangement connected to the second heater element of the first heater element array and the second heater element array. By connecting the first heater elements of each array together and connecting the second heater elements of each array individually together, the heater arrays can be controlled simultaneously and synchronously.

[0020] The heater may also include an air duct assembly; wherein at least one air outlet is formed in the air duct assembly, and the air duct assembly defines at least one cavity in which the plurality of heater elements are positioned. By forming an air outlet in the air duct assembly, the air duct assembly defines a cavity that serves as a path for airflow from an airflow generator.

[0021] The heater may also include a base supporting the air duct assembly, wherein an airflow generator is positioned within the base, and an airflow path is defined between the base and the air duct assembly. The cross-section of the opening in the air duct assembly may be annular, such as a capsule or ring. A capsule shape is a rectangle with semi-circular ends.

[0022] The control unit is also configured to control the airflow generator to regulate the airflow rate along the airflow path. The user interface allows the user to independently control the airflow rate and heating mode. Alternatively, the airflow rate and heating mode can be controlled together. For example, a low-power mode can be combined with a low airflow rate, and a high-power mode can be combined with a high airflow rate.

[0023] According to a second aspect of the present invention, a method for controlling the aforementioned heater is provided, the method comprising: operating a plurality of heater elements using a control unit in a first mode, wherein in the first mode a first number of the plurality of heater elements is turned on; or operating the plurality of heater elements using the control unit in a second mode, wherein in the second mode a second number of the plurality of heater elements is turned on; wherein the second number is greater than the first number.

[0024] According to a third aspect of the invention, a fan assembly is provided, comprising a first heater element and a second heater element arranged in series in an airflow path of the fan assembly; wherein the fan assembly further comprises an airflow generator configured to move air along the airflow path; wherein the fan assembly is configured to operate in a low-heat mode and a high-heat mode, wherein in the low-heat mode the first heater element is turned on, and in the high-heat mode both the first heater element and the second heater element are turned on.

[0025] The airflow generator may also include an impeller and a motor coupled to the impeller. The motor may be configured to rotate the impeller to draw air through the heater and along the main airflow path.

[0026] The heater may also include a control unit coupled to multiple heater elements. The control unit may include a user interface. The user interface allows the user to control the heater by turning it on / off, controlling fan speed, or adjusting heating modes. The user interface may include physical buttons or switches on the heater, or it may be a wireless interface provided via a dedicated wireless controller or a mobile device such as a mobile phone.

[0027] The control unit can be connected to multiple heater elements. A user interface can be connected to the control unit.

[0028] Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 A perspective view of a heater according to an example of this disclosure is shown;

[0030] Figure 2 It shows Figure 1 Front view of the heater;

[0031] Figure 3 It shows the way Figure 1 A sectional view of line AA;

[0032] Figure 4 It shows Figure 1 A block diagram of the heater control system for the heater;

[0033] Figure 5 It shows Figure 1 The operating method of the heater; and

[0034] Figure 6 The arrangement of the heater elements in an alternative embodiment of this disclosure is shown. Detailed Implementation

[0035] This disclosure relates to a heater. In one example, this disclosure relates to a heater for generating warm airflow in a room, office, or other domestic or commercial environment. Figure 1 and Figure 2An external view of heater 10 is shown. Heater 10 is in the form of a portable fan heater. Heater 10 includes a body 12, which includes an air inlet 14 through which the main airflow enters heater 10. The heater also includes an air duct assembly 16 (sometimes referred to as a nozzle) in the form of an annular housing mounted on the body 12, and which includes at least one air outlet 18 for discharging the main airflow from heater 10. In this example, the heater is a stand-alone fan heater. Alternatively, the heater could be part of an air purifier. The heater includes heater elements, which in Figure 1 They are not shown because they are inside heater 10. The heater elements will be described in more detail below.

[0036] The body 12 includes a generally cylindrical body portion 20. In this example, the height of the body 12 is in the range of 300 to 400 mm, and the diameter is in the range of 200 to 300 mm. The body portion 20 includes an air inlet 14 through which the main airflow enters the heater 10. In this example, the air inlet 14 includes an array of holes formed in the body portion 20. Alternatively, the air inlet 14 may include one or more grilles or meshes mounted in a window formed in the body portion 20. The body portion 20 is open at its upper end to allow the main airflow to exit from the body 12 to the air duct assembly 16.

[0037] The main body 20 includes a user interface 22 for the heater 10. The user interface includes multiple user-operable buttons for enabling a user to control various functions of the heater 10, a display for providing the user with visual indications, such as temperature settings of the heater 10, and user interface control circuitry connected to the buttons and display. In this example, the user interface 22 is positioned on a base. In other examples, the user interface 22 may be positioned in an alternative location, such as on the air duct assembly 16. The main body 20 is mounted on a base 24 for engaging the surface on which the heater 10 is located. The heater 10 also includes a motor and impeller housed within the main body 12. The impeller is positioned in the main airflow path. In use, the motor rotates the impeller to draw air along the main airflow path.

[0038] The air duct assembly 16 has an annular shape and extends around a central axis X to define an opening 26. An air outlet 18 for emitting the main airflow from the heater 10 is located at the front of the air duct assembly 16 and is arranged to guide the main airflow toward the front of the air duct assembly 16 through the opening 26. In this example, the air duct assembly 16 defines an elongated opening 26 with a height greater than its width, and the air outlet 18 is located on the opposite elongated side of the opening 26. In this example, the maximum height of the opening 26 is in the range of 400 to 500 mm, while the maximum width of the opening 26 is in the range of 50 to 150 mm. The inner annular periphery of the air duct assembly 16 includes a diffuser surface 28 located upstream of the air outlet 18.

[0039] Provided in WO 2013150264 A1 Figure 1 and Figure 2 Further details of the arrangement shown are incorporated herein by reference.

[0040] Figure 3 It shows along Figure 2 The image shows a cross-section of the air duct assembly 16 taken by line AA. The air duct assembly 16 includes an annular housing with a first side 32A and a second side 32B. The first side 32A and the second side 32B of the annular housing define a first air chamber 34A and a second air chamber 34B, respectively. The first air chamber 34A and the second air chamber 34B are fluidly connected to openings (not shown) in the base of the air duct assembly 16. The openings in the base of the air duct assembly 16 are fluidly connected to an opening at the upper end of the base 20. The main airflow leaving the main base 20 can then flow into the first air chamber 34A and the second air chamber 34B. Therefore, the main airflow branches into a first airflow through the first air chamber 34A and a second airflow through the second air chamber 34B.

[0041] Figure 3The specific arrangement shown is an example and is not intended to be limiting. The air duct assembly can be a housing of any shape suitable for a particular heater design. In one example, the housing may include a single airflow path with a single air inlet and a single air outlet. Various positions and orientations can be used to guide air in a particular direction. A common feature among the different examples is the use of at least two heater elements placed in series, such that airflow passes through one heater element before the other. In this sense, one heater element is upstream and one heater element is downstream. Several heater elements (three or more) can be arranged in this way to provide various heating levels. In one example, a single airflow path is provided through a series of heater elements, and a single air inlet and a single air outlet are provided. In an alternative example, the single airflow path through the heater elements may include multiple air inlets and / or multiple air outlets. For example, several air outlets allow air to be guided in several directions.

[0042] The first side 32A of the annular housing includes a first air outlet 18A. Within the first side 32A, a first heater channel 36A is defined by a first guide wall 30A and a first inner heater wall 38A. A first airflow passing through the first air chamber 34A passes along the first heater channel 36A and exits from the first air outlet 18A. A first heater array 40A is positioned within the first heater channel 36A. The first heater array 40A includes a first upstream heater element 42A and a first downstream heater element 44A. The first upstream heater element 42A and the first downstream heater element 44A are physically arranged in series. The first airflow passing through the first heater channel 36A first passes through the first upstream heater element 42A, then through the first downstream heater element 44A, and then exits the air duct assembly 16 via the first air outlet 18A.

[0043] A similar arrangement is used on the second side 32B of the annular housing. The second side 32B of the annular housing includes a second air outlet 18B. Within the second side 32B, a second heater passage 36B is defined by a second guide wall 30B and a second inner heater wall 38B. A second airflow passing through the second air chamber 34B passes along the second heater passage 36B and exits from the second air outlet 18B. A second heater array 40B is positioned within the second heater passage 36B. The second heater array 40B includes a second upstream heater element 42B and a second downstream heater element 44B. The second upstream heater element 42B and the second downstream heater element 44B are physically arranged in series. The second airflow passing through the second heater passage 36B first passes through the second upstream heater element 42B, then through the second downstream heater element 44B, and then exits the air duct assembly 16 via the second air outlet 18B.

[0044] Heater elements 42A, 42B, 44A, and 44B are all electrically connected to the heater controller. Heater elements 42A, 42B, 44A, and 44B may all have the same rated power. The term rated power refers to the maximum power that can be delivered by each heater element. When a heater element can only deliver one heating level, the rated power is the power value used by the heater element to deliver that heating level. Alternatively, upstream heater elements 42A and 42B may share the same rated power, which may differ from the rated power shared by downstream heater elements 44A and 44B. Heater elements 42A, 42B, 44A, and 44B may be formed of a positive temperature coefficient (PTC) ceramic material. Heater elements 42A, 42B, 44A, and 44B are not limited to using PTC ceramic material, and other suitable types of heater elements may be used. The electrical connections and operating modes will be described in more detail below.

[0045] Figure 4 This is a block diagram of a shared heater control system 50 according to an example of this disclosure. The heater control system 50 includes a first heater array 40A and a second heater array 40B. Figure 4 The first and second upstream heater elements 42A, 42B and the first and second downstream heater elements 44A, 44B are also shown. All heater elements are connected to a neutral terminal 52. The neutral terminal 52 is connected to the neutral line of the local power supply within the main body 20. The heater control system 50 also includes a live wire terminal 54, which is connected to the live wire of the local power supply within the main body 20. The live wire terminal 54 is connected to a power supply unit PSU 56, which is configured to convert the input power supply voltage to a suitable voltage for use with the heater elements 42A, 42B, 44A, 44B.

[0046] The heater control system 50 also includes a heater controller 58. The heater controller 58 is coupled to the PSU 56 and configured to deliver power to the heater elements. The heater controller 58 includes a first connection 60A to a first upstream heater element 42A and a second upstream heater element 42B, and a second connection 60B to a first downstream heater element 44A and a second downstream heater element 44B. Therefore, the heater controller 58 can independently control the upstream and downstream heater elements. The heater control system 50 also includes a system controller 59 and a user interface 22 (also...). Figure 1 (As shown in the diagram). User interface 22 is connected to system controller 59, which in turn is connected to heater controller 58. In an alternative embodiment, heater controller 58 may be independently connected to each heater element, thus allowing independent control of all heater elements.

[0047] The heater controller 58 includes multiple switches for controlling the heater elements. In one example, the heater controller 58 may include one switch for each heater element. The switches can be any type of power switch suitable for switching the heater elements. For example, the switches can be high-power MOSFETs or TRIACs. Other suitable arrangements will be apparent. Figure 3 and 4 In the example shown, upstream heater elements 42A and 42B have the same or substantially similar rated power as downstream heater elements 44A and 44B. Therefore, similar heating levels are achieved using either upstream heater elements 42A and 42B or downstream heater elements 44A and 44B. In this case, "substantially similar" takes into account manufacturing variations. For example, upstream heater elements 42A and 42B and downstream heater elements 44A and 44B can all operate within 5% of the target power.

[0048] User interface 22 includes multiple switches or buttons to enable a user to control heater 10. For example, user interface 22 may include an on / off switch and a heating mode switch. When heater 10 is on, a motor drives an impeller to draw air along the main airflow path. For clarity, operational details of the motor and impeller are omitted here. Further details of the motor and impeller are provided in WO 2013150264 A1. User interface 22 may also include switches or buttons to enable a user to select the motor speed. In this example, user interface 22 allows the user to select three heating modes. These modes are: a) no heating; b) low heat; and c) high heat. In one example, heater 10 can be controlled wirelessly. For example, heater 10 may include a wireless interface that can use WiFi™ or a short-range radio frequency protocol such as Bluetooth™. The wireless interface may form part of user interface 22 and perform the functions of an on / off switch or heating mode switch. Therefore, a user can control heater 10 using a dedicated wireless control or a mobile device such as a mobile phone. Now, in conjunction with... Figure 5 Describe the operation of heater 10.

[0049] In the first step S100, the user turns on the heater using the user interface 22. In response, the motor rotates the impeller to draw air through the heater 10. The air is discharged from the air outlet 18, allowing the air to circulate in the room where the heater 10 is located. In the next step S102, the user selects a heating mode using the user interface 22. The user can select a) no heating; b) low power; or c) high power. In an alternative example, the user can select a medium power option. If the user selects no heating, the heater controller 58 shuts down all heater elements (S104). If the user selects low power, the heater controller 58 turns on the first and second downstream heater elements 44A, 44B and shuts down the first and second upstream heater elements 42A, 42B (S106). In an alternative example, in the low power mode, the heater controller 58 can turn on the first and second upstream heater elements 44A, 44B and shut down the first and second downstream heater elements 42A, 42B. If the heater elements all have the same rated power, either the upstream or downstream heater element can be turned on. If the upstream and downstream heater elements have different rated power, this determines which heater elements are turned on in low-power mode. If the user selects high-power mode, all upstream and downstream heater elements are turned on (S108).

[0050] In this arrangement, the air heated by heater 10 is heated more uniformly. Because the upstream and downstream heater elements are all physically connected in series within their respective heater channels, all the air flowing in the first and second airflow paths passes through both heater elements. This ensures that all the air is heated uniformly. Conversely, if the heater elements were physically arranged partially or completely parallel (i.e., side-by-side), different portions of the airflow would be heated to different degrees in high-heat mode.

[0051] Figure 6 This is a representation of heater elements 42A, 42B, 44A, 44B according to another example of this disclosure. Figure 6 The heater elements shown are schematic and are not intended to accurately represent the dimensions, shape, or any other real-world parameters associated with the heater elements. In this example, the first and second upstream heater elements 42A, 42B have a first rated power, and the first and second downstream heater elements 44A, 44B have a second rated power. In this example, the first rated power is greater than the second rated power. This can be achieved by using larger PTC heater elements for the upstream heater elements 42A, 42B. This is in Figure 6The upstream heater elements 42A and 42B are shown in larger boxes. Assuming a combined power output of 100%, the upstream heater elements may contribute 60% or more of the total power, while the downstream heater elements may contribute 40% or less. In another example, the upstream heater elements may contribute 70% or more of the total power, while the downstream heater elements may contribute 30% or less. In yet another example, the upstream heater elements may contribute 80% or more of the total power, while the downstream heater elements may contribute 20% or less.

[0052] The rated power of heater 10 will depend on the country where the product is sold. For example, in the UK, the maximum total heater power may be approximately 2200 watts, and the minimum total heater power may be approximately 1100 watts. In Japan, the maximum total heater power may be 1500 watts, and the minimum total heater power may be approximately 500 watts.

[0053] In low-power mode, the first and second downstream heater elements 44A and 44B are turned on, and the first and second upstream heater elements 42A and 42B are turned off. In medium-power mode, the first upstream heater element 42A and the second upstream heater element 42B are turned on, and the first downstream heater element 44A and the second downstream heater element 44B are turned off. In high-power mode, all of the first and second upstream heater elements 42A and 42B, as well as the first and second downstream heater elements 44A and 44B, are turned on. In another example, the downstream heater elements 44A and 44B can provide a greater power contribution than the upstream heating elements at the same ratio as mentioned above.

[0054] In another example, each of the heater arrays 40A and 40B may include three or more heater elements. This arrangement can provide a wider range of heating modes than the example described above.

[0055] The examples above should be understood as illustrative. Other examples are contemplated. It should be understood that any feature described with respect to any example may be used alone or in combination with other described features, and may also be used in combination with one or more features of any other example, or in any combination of any other example. Furthermore, equivalents and modifications not described above may be employed without departing from the scope of the invention as defined in the appended claims.

Claims

1. A heater, comprising: At least one air inlet and at least one air outlet, wherein an airflow path is defined between the at least one air inlet and the at least one air outlet; An airflow generator is configured to draw air through the air inlet and along the airflow path; Multiple heater elements are positioned in the airflow path for heating air flowing along the airflow path, wherein the multiple heater elements are positioned in series with respect to each other in the airflow path; The control unit is configured to operate a plurality of heater elements in a first mode and a second mode, wherein in the first mode a first number of the plurality of heater elements is turned on, and in the second mode a second number of the plurality of heater elements is turned on, the second number being greater than the first number.

2. The heater according to claim 1, wherein, The plurality of heater elements are two heater elements, and the first quantity is one and the second quantity is two.

3. The heater according to claim 1 or 2, wherein, The first mode is a low-power mode, and the second mode is a high-power mode.

4. The heater according to any one of the preceding claims, wherein, The plurality of heater elements each have substantially similar rated power.

5. The heater according to any one of claims 1 to 3, wherein, The plurality of heater elements includes a first heater element having a first rated power and a second heater element having a second rated power higher than the first rated power.

6. The heater according to claim 5, wherein, The first mode includes turning on the first heater element but not turning on the second heater element, and the second mode includes turning on both the first heater element and the second heater element; wherein the control unit is further configured to operate the plurality of heater elements in a third mode, wherein in the third mode, the second heater element is turned on when the first heater element is not turned on.

7. The heater according to any one of the preceding claims, wherein, The plurality of heater elements are plurality of positive temperature coefficient heater elements.

8. The heater according to any one of the preceding claims further includes a user interface configured to allow the user to select an operating mode from a series of user-selectable operating modes including at least the first mode and the second mode.

9. The heater according to claim 8, wherein, The user interface includes at least one physical switch configured to allow the user to switch the heater between at least the first mode and the second mode.

10. The heater according to any one of the preceding claims, wherein, The control unit includes a plurality of heater switches connected to the plurality of heater elements and configured to turn the plurality of heater elements on or off based on the operating mode.

11. The heater according to any one of the preceding claims, wherein, The at least one air outlet includes two air outlets, wherein a first airflow path is defined between one of the two air outlets and the at least one air inlet, and a second airflow path is defined between the other of the two air outlets and the at least one air inlet.

12. The heater according to claim 11, wherein, The plurality of heater elements is a first heater element array positioned in the first airflow path, and the heater further includes a second heater element array positioned in the second airflow path for heating air flowing along the second airflow path.

13. The heater according to claim 12, wherein, The second heater element array includes a plurality of heater elements arranged in series in the second airflow path.

14. The heater according to claim 13, wherein, The control unit is further configured to operate the second heater element array such that, in the first mode, a first number of the plurality of heater elements is turned on, and in the second mode, a second number of the plurality of heater elements is turned on.

15. The heater according to any one of claims 12 to 14, wherein, Each of the first heater element array and the second heater element array includes a first heater element and a second heater element, and the control unit includes a first switch arrangement and a second switch arrangement, the first switch arrangement being connected to the first heater element of the first heater element array and the second heater element array, and the second switch arrangement being connected to the second heater element of the first heater element array and the second heater element array.

16. The heater according to any one of the preceding claims further includes an air duct assembly; wherein the at least one air outlet is formed in the air duct assembly, and the air duct assembly defines at least one cavity in which the plurality of heater elements are positioned.

17. The heater of claim 16, further comprising a base supporting the air duct assembly, wherein the airflow generator is positioned within the base and the airflow path is defined between the base and the air duct assembly.

18. The heater according to any one of the preceding claims, wherein, The control unit is also configured to control the airflow generator to adjust the flow rate of the air along the airflow path.

19. A method for controlling a heater according to any one of claims 1 to 18, the method comprising: The control unit is used to operate the plurality of heater elements in the first mode, in which a first number of the plurality of heater elements are turned on; or The control unit is used to operate the plurality of heater elements in a second mode, in which a second number of the plurality of heater elements is turned on; wherein the second number is greater than the first number.

20. A fan assembly, the fan assembly comprising a first heater element and a second heater element arranged in series in an airflow path of the fan assembly; wherein, The fan assembly further includes an airflow generator configured to move air along the airflow path; wherein the fan assembly is configured to operate in a low-heat mode and a high-heat mode, wherein in the low-heat mode the first heater element is turned on, and in the high-heat mode both the first heater element and the second heater element are turned on.

Images