A fan heater and a heater module

Abstract

A fan heater comprises an air duct 16 defining an airflow pathway between an inlet 46 and an outlet 18. A heater module 48 is releasably connected within the air duct such that the airflow path passes through the heater module. The air duct has an opening, which may be the air inlet, through which the heater module is removable from the air duct. The heater module may comprise a two-part mechanism for releasably attaching the heater module. The mechanism allows the heater module to be attached and detached via access to a first part of the mechanism which is at a first end of the heater module positioned proximal to the opening. A second part of the mechanism at a second end of the heater module may be actuated from the first end of the heater module. The second part may be a snap-fit mechanism, or a hook and cantilever mechanism.

Description

Background Fan heaters produce warm air by creating an airflow over one or more heater elements. They may be used in domestic or commercial environments to heat a room or person. Some fan heaters are formed as portable heaters that may be easily moved by the user. The heater elements may be formed in an airflow path within a compartment of the fan heater. Air is expelled over the heater element and out of the fan heater via a set of exhausts. Summary According to a first aspect of the present invention, there is provided a fan heater, comprising: an air duct assembly having an air inlet and an air outlet, the air duct assembly defining an airflow path between the air inlet and the air outlet; and a heater module, disposed within the air duct assembly, the heater module being releasably connected to the air duct assembly, the airflow path passing through the heater module to the air outlet; wherein the air duct assembly includes an opening through which the heater module is removable from the air duct assembly. In domestic appliances, certain components are likely to fail earlier than others. In the case of fan heaters, the heater modules are one of the components which may fail early. This is, at least in part, due to their use at high temperatures and regular cycling on and off. A problem with fan heaters is that the heater elements are typically designed to be inaccessible. They may be attached to the fan heater in such a way that they cannot be removed once they have been installed. For example, they may be glued in place. Even if they are attached in such a way that they might be removed, they may be located within a compartment which is inaccessible without destroying the appliance. Additionally, even if the heater module can be accessed without destroying the device, it may be very difficult or impossible to fully reassemble the device. If reassembly is possible, it may be difficult to do without creating “leak paths” through which air can leak into or out of the fan heater, thereby decreasing the efficiency of the device. In this example, a fan heater is provided with a releasable heater module that is removable from the air duct assembly via the opening. This enables the heater module to be replaced, repaired, serviced or inspected, without completely disassembling the fan heater. The heater module may include an attachment mechanism for releasably connecting the heater module to the air duct assembly. The attachment mechanism may have a first portion positioned proximal to the opening of the air duct assembly. The opening may provide limited access to the internal space of the air duct assembly. The attachment mechanism therefore includes a first portion which may be accessible via the opening. The heater module may be detached in use from the air duct assembly even though the user may only have access to the end of the heater module that is nearest to the opening. The heater module may be elongate and include a first end, proximal to the opening, and a second end, distal from the opening. The first portion of the attachment mechanism may be located proximal to the opening (such as, at the first end of the heater module) and may be accessible by a user via the opening. The second end of the heater module may be difficult to access. However, the user may access the first portion of the attachment mechanism. The first portion of the attachment mechanism may be directly operated by a user to release the heater module from the air duct assembly. The first portion of the attachment mechanism may be a user operable mechanism, such as a screw or clip, that may be operated directly using a screwdriver or the user’s hand. The attachment mechanism may include a second portion, located distal from the opening (such as, at the second end of the heater module). The second portion of the attachment mechanism may be actuatable by a user from the first end of the heater module. The second portion of the attachment mechanism may not require direct access by the user. Instead, the second portion may be operated by performing an action at the first end of the heater module. This enables removal of the heater module without direct access to the second end of the heater module. The second portion of the attachment mechanism may be actuatable by lifting the first end of the heater module away from (e.g., out of) the air duct assembly, in order to release the heater module from the air duct assembly. The second portion of the attachment mechanism may be a snap-fit mechanism. For example, the second portion of the attachment mechanism may be a hook and cantilever mechanism. The cantilever may be positioned at the second end of the heater module and the hook may be positioned on the air duct assembly, wherein the cantilever is configured to engage with the hook to hold the heater module in place. Alternatively, the cantilever may be positioned on the air duct assembly and the hook may be positioned at the second end of the heater module. A user may undertake a lifting motion without requiring the use of specialist tools. As an alternative to a lifting motion, the heater module may be removed using a pivoting or tilting motion. A hook and cantilever mechanism is one that may be released without direct access by lifting one end of the heater module. In once example, the second portion of the attachment mechanism may be released by lifting the first end of the heater module such that the angle between the heater module and the air duct assembly is no more than 10 degrees. In an alternative example, the second portion of the attachment mechanism may be released by lifting the first end of the heater module so that it forms an angle of between 5 and 15 degrees with the air duct assembly. Optionally, the heater module is released when it is moved to around 10 degrees. The opening in the air duct assembly may be the air inlet and the opening may have a width. The heater module may be elongate and may have an elongate length. The elongate length may be greater than the width of the opening. The opening may define a plane, and the width of the opening may be aligned with the plane. The heater module may be disposed in the air duct assembly such that an elongate axis of the heater module is substantially perpendicular to the plane. The heater module may be removed from the air duct assembly such that the elongate axis intersects the plane of the opening. This enables the heater module to be removed from the air duct assembly, despite the elongate length of the heater module being greater than the width of the opening. The opening may also be referred to as a service or access opening. The heater module may include a heater chassis and a heater element. The heater chassis may define a conduit within which the heater element is positioned, such that in use air flowing through the heater module passes over the heater element towards the air outlet. The conduit may define part of the airflow path. The part of the airflow path that passes through the conduit takes a primary direction through the conduit. This is the direction that the majority of the air travels, when passing along the airflow path through the conduit. In this example, when the fan heater is located on a horizontal surface, such as a floor, the primary direction is substantially horizontally. The heater chassis may include an air inlet end having an inlet edge portion, and an air outlet end having an outlet edge portion. Each edge portion may define a periphery of the conduit. The outlet edge portion of the heater chassis may form a seal with a complementary edge portion of the air duct assembly, positioned around the air outlet of the air duct assembly. The primary direction of airflow through the conduit is from the air inlet end to the air outlet end. The seal may be a labyrinth seal. The heater module may be connected to the air duct assembly in such a way that vibration may be reduced. A seal is therefore formed around a peripheral edge of the heater chassis with the air duct assembly. This also helps to prevent air ingress from outside of the heater chassis through the join between the heater module and the air duct assembly. This improves efficiency and reduces noise. Other types of seals that provide sufficient air leakage prevention may be used. The heater element includes an air outlet side. At least a portion of the air outlet end of the heater chassis is offset from the heater element air outlet side. This may be achieved by offsetting at least a portion of the outlet edge portion from the outlet side of the heater element. The offset portion may be along the elongate side of the heater chassis. The heater module may be elongate in a direction perpendicular to the primary direction of airflow through the conduit. The air outlet side of the heater element may be substantially planar. The at least a portion of the air outlet end of the heater chassis is parallel to the plane of the air outlet side of the heater element. By offsetting the air outlet end of the heater chassis and the air outlet end of the heater element, the efficiency of the seal is improved, as air is less likely to ingress the airflow pathway. The air duct assembly may comprise an exhaust chassis, positioned between the air outlet of the air duct assembly and the heater chassis. The heater chassis may be aligned with and removably connected to the exhaust chassis, such that the airflow path passes through the heater chassis and the exhaust chassis to the air outlet. To provide a smooth airflow out of the fan heater, an exhaust is typically provided between the heater element and the air outlet. That is, a separate exhaust chassis may be provided between the heater module and the airflow outlet. The exhaust chassis may be integral with or otherwise connected to the air duct assembly. Air flow through the exhaust chassis may be in substantially a same primary direction as through the heater module. The exhaust chassis may include an air inlet end having an inlet edge portion defining a periphery of the exhaust chassis. The complementary edge portion of the air duct assembly may be the inlet edge portion of the exhaust chassis. To help ensure a good seal between the heater chassis and the exhaust chassis, the outlet edge portion of the heater chassis and the inlet edge portion of the exhaust chassis may have a complementary profile. As such, the edge portions are closely aligned, thereby helping to reduce the possibility of air ingress into the airflow path. The fan heater may further comprise a main body. The air duct assembly may include an interface portion for coupling the air duct assembly to the main body. The opening may be formed in the interface portion. The main body may include an airflow generator. The fan heater may further comprise electrical wiring, coupled to and for providing power to the heater module. The electrical wiring may pass through the opening in the interface portion to a power supply in the main body. The opening between the air duct assembly and the main body is typically used for air to flow between the main body and the air duct assembly. By utilising the same opening to remove the heater module, the overall design of the fan heater may be simplified. The air duct assembly may be an annular air amplifier having two elongate side portions. The fan heater may comprise two heater modules, one positioned within each elongate side portion of the air duct assembly. The fan heater may comprise two air outlets, one positioned in each elongate side portion of the air duct assembly. A primary direction of airflow through the heater module may be perpendicular to a primary direction of airflow through the opening between the air duct assembly and the main body. In this example, the primary direction of airflow through the opening in the air duct assembly is in a substantially vertical direction. In this example, the primary direction of airflow out of the fan heater (e.g., from the air outlet(s)) is in a substantially horizontal direction. According to a second aspect of the present invention, there is provided a heater module for use with the fan heater of any preceding clause relating to the first aspect of the present invention. According to a third aspect of the present invention, there is provided a heater module for use with a fan heater, the heater module comprising: a two-part attachment mechanism for releasably attaching the heater module to a fan heater, wherein the two-part attachment mechanism is configured to enable a user to attach and detach the heater module via access to a first part of the two-part attachment mechanism. The heater module may be elongate. The first part of the two-part attachment mechanism may be located at a first end of the heater module. A second part of the two-part attachment mechanism may be located at a second end of the two-part attachment mechanism. The second part may be actuated via user access to the first part. The second part may be a cantilever for coupling to a hook positioned on the fan heater. The heater module may further comprise a heater chassis and a heater element supported within the heater chassis. The heater chassis may define an airflow conduit having an air inlet end and an air outlet end. The air outlet end may be configured to form a seal with an exhaust chassis of the fan heater. The heater module may be elongate in a direction perpendicular to a direction of airflow through the conduit. The heater element may include a planar side portion configured to face the exhaust chassis. At least a portion of the air outlet end forming the seal may be offset from the planar side portion of the heater element. Further features and advantages of the invention will become apparent from the following description of preferred examples of the invention, given by way of example only, which is made with reference to the accompanying drawings. Brief Description of the Drawings Figure 1 shows a perspective view of a fan heater in accordance with an example of the disclosure; Figure 2 shows an exploded perspective view of an air duct assembly and heater modules in accordance with an example of the disclosure; Figure 3 shows a side view of the air duct assembly of Figure 2; Figure 4 shows a perspective view of an inner casing section and heater modules of the air duct assembly of Figure 3; Figure 5 shows a perspective view of a heater module and exhaust chassis in accordance with an example of the disclosure; Figure 6 shows an exploded perspective view of the heater module and exhaust chassis of Figure 5; Figure 7 shows a side view of the heater module and exhaust chassis of Figure 5, with the heater module illustrated in three different positions; Figures 8 shows a perspective view of the heater module of Figure 7 showing part of an attachment mechanism in accordance with an example of the disclosure; Figures 9 shows a further perspective view of an end of the heater module of Figure 7 showing part of the attachment mechanism in accordance with an example of the disclosure; Figures 10 shows a further perspective view of an end of the heater module of Figure 7 showing part of the attachment mechanism in accordance with an example of the disclosure; Figure 11 shows a cross-section of the inner casing section, heater module and exhaust chassis in accordance with an example of the disclosure; and Figures 12A to 12F show the steps of removing the heater modules from the air duct assembly in accordance with an example of the disclosure. Detailed Description Figure 1 illustrates an external view of a fan heater 10. In one example, the present disclosure relates to a fan heater for creating a warm air current in a room, office, or other domestic or commercial environment. The fan heater 10 is in the form of a portable fan heater. The fan heater 10 comprises a body 12 comprising an air inlet 14 through which a primary airflow enters the fan heater 10. The fan heater also comprises an air duct assembly 16 (sometimes referred to as a nozzle) in the form of an annular casing mounted on the body 12. The air duct assembly 16 comprises at least one air outlet 18 for emitting the primary airflow from the fan heater 10. In this example, the heater is a standalone fan heater. As an alternative, the heater may be part of an air purifier. The heater includes at least one heater module, which is not shown in Figure 1 as it is internal to the fan heater 10. The heater module will be described in more detail below. The body 12 comprises a substantially cylindrical main body section 20. In this example the body 12 has a height in the range from 300 to 400 mm, and a diameter in the range from 200 to 300 mm. The main body section 20 comprises the air inlet 14 through which the primary airflow enters the fan heater 10. In this example the air inlet 14 comprises an array of apertures formed in the main body section 20. Alternatively, the air inlet 14 may comprise one or more grilles or meshes mounted within windows formed in the main body section 20. The main body section 20 is open at the upper end thereof to allow the primary airflow to be exhausted from the body 12 to the air duct assembly 16. The main body section 20 comprises a user interface 22 of the fan heater 10. The user interface 22 comprises a plurality of interactive controls for enabling a user to control various functions of the heater 10. The user interface 22 also includes a display for providing the user with, for example, a visual indication of a temperature setting of the heater 10, and a user interface control circuit connected to the interactive controls and the display. In this example, the user interface 22 is positioned on the main body section 20. In other examples, the user interface 22 could be positioned in alternative locations, such as on the air duct assembly 16. The body 20 is mounted on a base 24 for engaging a surface on which the fan heater 10 is located. The fan heater 10 also includes a motor and an impeller, housed within the body 12. The impeller is positioned in a primary airflow path. In use, the motor turns the impeller to draw air along the primary airflow path. The air duct assembly 16 has an annular shape, extending about a central axis to define a passageway 26. The air outlet 18 for emitting the primary airflow from the fan heater 10 is located towards the front of the air duct assembly 16 and arranged to direct the primary airflow away from the front of the air duct assembly 16. In this example, the air duct assembly 16 defines the passageway 26, which is elongate and has a height greater than its width. In this example, the maximum height of the passageway 26 is in the range from 400 to 500 mm, whereas the maximum width of the passageway 26 is in the range from 50 to 150 mm. An inner annular periphery of the air duct assembly 16 comprises a diffuser surface 28. The diffuser surface 28 is arranged to taper away from the central axis of the passageway 26. The angle subtended between the diffuser surface 28 and the central axis of the passageway 26 is in the range from 5 to 25°, and in this example is around 7°. A tapered surface 30 is located downstream from the diffuser surface 28, terminating at the air outlet 18. The angle subtended between the tapered surface 30 and the central axis of the passageway 26 is preferably around 45°. The fan heater 10 also includes a power cable 32 and plug 34 for receiving power from a wall socket. In other examples, the fan heater 10 may be battery powered and include a battery pack within the body 12. Further details of the arrangement shown in Figure 1 is provided in WO 2013150264 Al, the contents of which are hereby incorporated by reference. With reference to Figures 2 and 3, the air duct assembly 16 comprises an annular outer casing section 36 connected to and extending about an annular inner casing section 38. Each of these sections may be formed from a plurality of connected parts, but in this example each of the casing sections 36, 38 is formed from a respective, single moulded part. The inner casing section 38 defines the central passageway 26 of the air duct assembly 16, and has an external surface 40 which is shaped to define the diffuser surface 28 and tapered surface 30. The outer casing section 36 and the inner casing section 38 together define an annular interior passage of the air duct assembly 16. The interior passage extends about the passageway 26, and thus comprises two relatively straight sections each adjacent a respective elongate side of the passageway 26, an upper curved section joining the upper ends of the straight sections, and a lower curved section joining the lower ends of the straight sections. The interior passage is bounded by an internal surface 42 of the outer casing section 36 and the external surface 40 of the inner casing section 38. The outer casing section 36 comprises an interface portion 44 which is configured to be connected to, and over, an open upper end of the body 12. The interface portion 44 of the outer casing section 36 comprises an air duct assembly air inlet 46 through which the primary airflow enters the lower curved section of the interior passage from the body 12. Within the lower curved section, the primary airflow is divided into two airflows which each flow into a respective one of the straight sections of the interior passage. The fan heater 10 also comprises a pair of heater modules 48A, 48B. Each heater module 48A, 48B comprises a heater element 50A, 50B and a heater chassis 52A, 52B. In Figures 2 and 3 the heater elements 50A, 50B are shown separate from the heater chassis 52A, 52B. However, once assembled, the heater elements 50A, 50B are attached to and held within their respective heater chassis 52A, 52B, as will be described in more detail below. The heater elements 50A, 50B are preferably formed from positive temperature coefficient (PTC) ceramic material. The air duct assembly 16 also comprises a pair of exhaust chassis 54A, 54B. Each exhaust chassis 54A, 54B is configured to be connected to the inner casing section 38. Each exhaust chassis 54A, 54B is configured to be disposed in a respective straight section of the interior passage, adjacent a respective elongate side of the passageway 26. Each exhaust chassis 54A, 54B comprises a plurality of exhaust channels which are oriented such that when the exhaust chassis 54A, 54B are aligned with respective air outlet portions 18A, 18B of the air outlet 18, air may flow from the interior passage and out of the air duct assembly 16. The direction of airflow out of the air outlet portions 18A, 18B is parallel to the central axis of the passageway 26, which in normal use is substantially horizontal. The exhaust chassis 54A, 54B are configured to be connected to the inner casing section 38 using an airtight interface. This is to prevent air leaking into the exhaust channels during use, which can create unwanted noise or decrease the efficiency of the fan heater 16. This may be achieved by gluing, using labyrinth seals, screws, or a combination of these. The purpose of the exhaust chassis 54A, 54B is to provide a smooth airflow out of the air outlet 18. This creates a better experience of the user, reduces airflow-related noise, and improves efficiency. The heater modules 48A, 48B are configured to be releasably connected to the air duct assembly 16. In this example, they are releasably connected to respective exhaust chassis 54A, 54B. The releasable connection will be described in more detail below. The direction of airflow through the heater modules 48A, 48B is also in parallel to the central axis of the passageway 26. The heater modules 48A, 48B are also aligned with the exhaust chassis 54A, 54B such that the airflow through the heater modules 48A, 48B is aligned with the airflow through the exhaust chassis 54A, 54B. The fan heater 10 also includes a wiring loom 56 (also referred to as a harness) for supplying electrical power to the heater modules 48A, 48B. Once assembled, the wiring loom 56 is connected to electrical terminals of each heater element 50A, 50B. The wiring loom 56 may also be connected to thermal sensors (not shown in Figures 2 and 3) for detecting overheating. The wiring loom 56 is in turn connected to a heater control circuit located in the body 12. The heater control circuit may be controlled by control signals supplied thereto by the user interface 22. Figure 4 illustrates the inner casing section 38 of the air duct assembly 16. The inner casing section 38 is shown orientated 180° relative to Figure 2. In Figure 4, the exhaust chassis 54A, 54B and the heater modules 48A, 48B are shown fully assembled. The exhaust chassis 54A, 54B are glued and screwed in place, and aligned with their respective air outlets 18A, 18B. For example, the exhaust chassis 54A, 54B are retained in place using upper exhaust chassis retaining brackets 5 8A, 58B. Lower exhaust chassis retaining brackets are included at the lower end of the air duct assembly, although they are not visible in Figure 4. The heater modules 48A, 48B are releasably connected to the air duct assembly 16 via the exhaust chassis 54A, 54B. The releasable connection is made using a two-part attachment mechanism. In connection with the heater module 48B, a first part 60 of the two-part attachment mechanism is located at first end 62B of the heater module 48B. This is the lower end of the heater module 48B, when assembled. The first end 62B of the heater module 48B is proximal the interface portion 44 of the outer casing section 36. It is also proximal the air duct assembly air inlet 46. The air duct assembly air inlet 46 is an opening through which access to the heater modules 48A, 48B may be achieved once the air duct assembly 46 is fully assembled. This opening may be referred to as a service opening. It should be noted that once the inner and outer casing sections 38, 36 have been assembled during manufacturing, they are not intended to be disassembled by a customer or a qualified service engineer. This is because the seal formed between the two casing sections is designed to reduce noise owing to air leakage and to improve efficiency. As such, the air duct assembly 16 is not designed to be disassembled. However, the air duct assembly 16 is designed to be removable from the body 12. Given this, the service opening 46 represents the only opening through which access to the heater modules 48A, 48B may be gained. As a user may gain access to the first part 60 via the opening 46, a secure attachment mechanism, such as a screw and bracket may be used. Alternatively, a clip arrangement may be used. Alternatively, any attachment mechanism which is user operable by direct access to the first end 62B of the heater module 48B may be used. A second end 64B of the heater module 48B includes a second part 66 of the two-part attachment mechanism. The second end 64B of the heater module 48B is at the upper end of the air duct assembly 16, when assembled. The second end 64B is located distal from the interface portion 44 of the outer casing section 36. It is also distal from the air duct assembly air inlet 46 and is therefore difficult or impossible for a user to access directly when the air duct assembly 16 is fully assembled. The second part 66 is actuatable from the first end 62B of the heater module 48B. In this example, the second part 66 is a hook and cantilever mechanism, as will be described in more detail below. The heater chassis 52A, 52B also include thermal sensor retaining portions 68A, 68B. These portions are for retaining thermal sensors (not visible in Figure 4) for monitoring the heater module 48A, 48B temperature, and for enabling the heater control circuit to cut off the heater elements 50A, 50B in the event of overheating. Figures 5 and 6 illustrate a heater module 48, including a heater element 50 and heater chassis 52, and an exhaust chassis 54. These components may be either of the heater modules 48A, 48B, heater elements 50A, 50B, heater chassis 52A, 52B and exhaust chassis 54A, 54B. The air duct assembly 16 is omitted in these figures for clarity. Figure 5 shows the heater module 48 in position on the exhaust chassis 54. In addition to the features previously described, a thermal sensor 70 is retained by the thermal sensor retaining portion 68. The thermal sensor retaining portion 68 and the thermal sensor 70 are positioned at a midpoint along the heater element 50, between a first end 62 and the second end 64 of the heater module 48. The heater module 48 also includes thermal sensor wiring 72 for coupling the thermal sensor 70 to the wiring loom 56. Additionally, the heater module 48 includes heater element wiring 74 for coupling the heater element 50 to the wiring loom 56. Figure 6 shows an exploded view of the heater element 50, heater chassis 52 and exhaust chassis 54. The heater element 50 is generally shaped as an elongate cuboid, and is elongate along a primary heater axis. When the heater module 48 is assembled, the primary heater axis is oriented in a substantially vertical direction, and is substantially perpendicular to the central axis of the passageway 26. The heater element 50 may be a positive temperature coefficient (PTC) heater that includes a plurality of closely spaced fins 76. The fins 76 extend from one side of the heater element 50 to another side, in a direction perpendicular to the primary heater axis. The fins 76 are therefore aligned in the direction of airflow through the heater element 50 that is perpendicular to the primary heater axis and parallel to the central axis of the passageway 26. The heater fins 76 are surrounded by a casing 78 along each elongate side of the heater element 50. A first end 80 of the heater element 50 proximal the first end 62 of the heater module 48 includes a pair of electrical connections 82 for connecting the heater element 50 to the heater element wiring 74. The heater element wiring 74 includes a pair of heater element connectors 84 for coupling the heater element wiring 74 to the pair of electrical connections 82. A second end 86 of the heater element 50, proximal to the second end 64 of the heater module 48, includes a pair of protruding fins 88. The protruding fins 88 extend away from the second end 86 of the heater element 50 in a direction parallel to primary heater axis. The protruding fins 88 are for insertion into complementary openings in the corresponding ends of the heater chassis 52. The protruding fins 88 help retain the heater element 50 within the heater chassis 52. The heater chassis 52 is also generally shaped as an elongate cuboid. An inner surface 90 of the heater chassis 52 is shaped to be complementary to the outer surface of the heater element 50, such that the heater chassis 52 may receive the heater element 50. The heater chassis 52 is open along one elongate side to receive the heater element 50. The heater chassis 52 is also open along a side opposing the side that receives the heater element 50, in order for air to flow out of the heater element 50 towards the exhaust chassis 54. The heater chassis 52 therefore defines a conduit within which the heater element 50 is disposed and in which air flows. The heater chassis 52 includes an air inlet side 92 and an air outlet side 94. The heater chassis 52 includes an inlet edge portion 96 which defines the entry to the conduit formed by the heater chassis 52. The heater chassis 52 also includes an outlet edge portion 98 which defines the exit to the conduit formed by the heater chassis 52. The inlet edge portion 96 is substantially aligned with a plane formed by an inlet side of the heater element 50. Conversely, the outlet edge portion 98 is offset from a plane formed by the outlet side of the heater element 50 along a majority of the outlet edge portion 98. At the second end 64 of the heater chassis 52, the outlet edge portion 98 is aligned with the outlet side of the heater element 50. This enables the heater element 50 to be held in place, for example by the protruding fins 88. Along each elongate side of the heater chassis 52, the outlet edge portion 98 is offset from the heater element 50 along a portion of the elongate side. In this example, the outlet edge portion 98 has a trapezoidal profile when viewed from the side. Other profiles may be used. The outlet edge portion 98 is shaped in a complementary manner, and forms a seal with, an inlet edge of the exhaust chassis 54, as will be explained below. The end of the heater chassis 52 proximal the second end 64 of the heater module 48 includes a cantilever 100. The cantilever 100 is shaped as a beam protruding away from the second end 64 of the heater module 48 in a direction aligned with primary heater axis. The cantilever 100 is for engaging with the exhaust chassis 54, as will be described below. The heater module 48 also includes a heater chassis cover 102 and a heater chassis cover fixing screw (not shown). The heater chassis cover 102 is for placing on top of the heater element 50 once it is in position in the heater chassis 52, in order to fix it in place. Other user operable fixing mechanisms such as clips or hand-screwed fixings may be used. The exhaust chassis 54 also takes a shape similar to an elongate cuboid. The exhaust chassis 54 includes a plurality of exhaust channels 106 which pass from an inlet side to an outlet side of the exhaust chassis 54. The exhaust channels 106 are for smoothing the airflow from the heater element 50 prior to the airflow exiting the air duct assembly via air outlet 18. The inlet side of the exhaust chassis includes an edge profile 108 that is complementary to the outlet edge portion 98 of the heater chassis 52. As such, a portion of the heater element 50 is disposed within a channel formed by the inlet edges of the exhaust chassis 54. A seal may be formed between the heater chassis 52 and the exhaust chassis 54 along the complementary edges. The seal may be a labyrinth seal or other suitable seal. The benefit of offsetting the seal from the edge of the heater element 50 is that air is less likely to leak through the seal into the airflow path. The heater chassis 52 and exhaust chassis 54 together form an air outlet conduit, formed partially from the heater chassis 52 conduit and partially from the exhaust channels 106 of the exhaust chassis 54. The air outlet conduit has a cross-sectional profile which substantially rectangular, being elongate in one direction. The seal between the heater chassis 52 and exhaust chassis 54 is therefore formed part way along the air outlet conduit. A major portion of the heater element 50 is disposed within the heater chassis 52. The seal is arranged such that a minor portion of the heater element 50 is disposed within the exhaust chassis 54. In this regard, a portion of the seal is offset from the air outlet end of the heater element 50. The exhaust chassis 54 also includes a cantilever receiving portion 110 (otherwise referred to as a hook) at an end of the exhaust chassis 54 proximal the second end 64 of the heater module 48. The cantilever receiving portion 110 includes an opening for receiving the cantilever 100. The cantilever mechanism will be described in more detail below. Figures 7 and 8 show a side view of the heater chassis 52 and exhaust chassis 54. In Figure 7, the heater chassis 52 is shown in three different positions Pl, P2 and P3, to demonstrate the operation of the second part 66 of the two-part attachment mechanism. The second part 66 includes the cantilever 100. The cantilever 100 is configured to fit through an opening in the cantilever receiving portion 110. In position Pl, the second end 64 of the heater chassis 52 is positioned against the exhaust chassis 54 with the cantilever 100 located in the cantilever receiving portion 110. The first end 62 of the heater chassis 52 is positioned away from the exhaust chassis 54 such that the heater module 48 forms an angle with the exhaust chassis 54. This angle may be 15° or less. In this example the angle may be no more than 10°. As the heater chassis 52 is lowered towards the exhaust chassis 54 through position P2 and into position P3, the cantilever 100 moves against the cantilever receiving portion 110. This forces the outlet edge portion 98 against the exhaust chassis 54, forming a seal between the heater chassis 52 and the exhaust chassis 54. The cantilever receiving portion 110 includes a safety rib 112 which is configured to engage with a safety fin 114 that protrudes from an edge of the heater chassis 52. The safety fin 114 is held within the safety rib 112 to prevent the heater chassis 52 moving away from the exhaust in the event the cantilever 100 fails. The heater chassis 52 is fixed in place using the heater chassis cover fixing screw. Figures 9 and 10 illustrate the second part 66 of the two-part attachment mechanism in greater detail. In addition to the cantilever receiving portion 110, an opening 116 is shown. In some embodiments, the cantilever 100 may include a tapered barb (not shown) disposed at an end of the cantilever 100 distal from the body of the heater chassis 52. Alternatively, or additionally, the cantilever 100 may form a U-shape (not shown). In embodiments, the cantilever 100 may comprise at least a portion which tapers away from the heater chassis 52 to a narrow point at the tip of the cantilever 100. Figure 11 shows a cross-section through the heater element 50A, the heater chassis 52A and the exhaust chassis 54A. A labyrinth seal is formed between the outlet edge portion 98A of the heater chassis 52A and the inlet edge of the exhaust chassis 54A. This seal is formed around the periphery of the interface between the heater chassis 52A and the exhaust chassis 54A. The seal reduces air leakage into the airflow path, reducing unwanted noise and improving efficiency. Other air leak resistant seals may be used to provide the necessary resistance to air leakage. Figures 12A to 12G show the steps for removing the heater modules 48A, 48B from the air duct assembly 16. This procedure is possible by accessing the heater modules 48A, 48B through the opening 46 in the interface portion 44 of the air duct assembly 16. Firstly, as shown in Figure 12A, the air duct assembly 16 is removed from the body 12. This may be done using any suitable mechanism. For example, the air duct assembly 16 may be attached using screws. Alternatively, the air duct assembly 16 may itself be screwed onto the body 12. In Figure 12B, a loom cover panel 120 is removed to expose the wiring loom 56. The screws retaining the heater modules 48A, 48B are then removed from the first part 60 of the attachment mechanism. The first end of the heater modules 48A, 48B are then lifted to an angle of approximately 10°, as shown in Figure 12C. In Figure 12C, the outer casing section 36 is omitted for clarity. This enables the cantilevers 100A, 100B to be disengaged with the cantilever retaining portions 110A, 110B, and for the heater modules 48A, 48B to be removed from the exhaust chassis 54A, 54B. Figure 12D shows the heater modules 48A, 48B and the wiring loom 56 partially removed from the air duct assembly 16. In Figure 12D, the outer casing section 36 is omitted for clarity. Once the heater modules have been fully removed from the air duct assembly 16, the retaining covers 102A, 102B may be removed, as shown in Figure 12E. The heater elements 50A, 50B may then be removed from the heater chassis 52A, 52B, as shown in Figure 12F. The wiring loom 56 may then be disconnected. The heating elements may then be repaired, replaced or serviced as required. The air duct assembly 16 may then be reassembled and reattached to the body 12 by following Figures 12A12F in the reverse order. The above examples are to be understood as illustrative. Further examples are envisaged. It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

1. A fan heater, comprising:an air duct assembly having an air inlet and an air outlet, the air duct assembly defining an airflow path between the air inlet and the air outlet; anda heater module, disposed within the air duct assembly, the heater module being releasably connected to the air duct assembly, the airflow path passing through the heater module to the air outlet; whereinthe air duct assembly includes an opening through which the heater module is removable from the air duct assembly.

2. A fan heater according to claim 1, wherein the heater module includes an attachment mechanism for releasably connecting the heater module to the air duct assembly, the attachment mechanism having a first portion positioned proximal to the opening of the air duct assembly.

3. A fan heater according to claim 2, wherein the heater module is elongate and includes a first end, proximal to the opening, and a second end, distal from the opening, wherein the first portion of the attachment mechanism is located at the first end of the heater module and is accessible by a user via the opening.

4. A fan heater according to claims 2 or 3, wherein the first portion of the attachment mechanism is a user operable mechanism.

5. A fan heater according to claim 3, wherein the attachment mechanism includes a second portion, positioned at the second end, the second portion of the attachment mechanism being actuatable by a user from the first end of the heater module.

6. A fan heater according to claim 5, wherein the second portion of the attachment mechanism is actuatable by lifting the first end of the heater module away from the air duct assembly, in order to release the heater module from the air duct assembly.

7. A fan heater according to claim 6, wherein the second portion of the attachment mechanism is a snap-fit mechanism.

8. A fan heater according to claims 6 or 7, wherein the second portion of the attachment mechanism is a hook and cantilever mechanism, the cantilever being positioned at the second end of the heater module and the hook being positioned on the air duct assembly, wherein the cantilever is configured to engage with the hook to hold the heater module in place.

9. A fan heater according to any preceding claim, wherein the opening in the air duct assembly is the air inlet and the opening has a width, and wherein the heater module is elongate and has an elongate length, the elongate length being greater than the width of the opening.

10. A fan heater according to any preceding claim, wherein the heater module includes a heater chassis and a heater element, the heater chassis defining a conduit within which the heater element is positioned, such that in use air flowing through the heater module passes over the heater element towards the air outlet.

11. A fan heater according to claim 10, wherein the heater chassis includes an air inlet end having an inlet edge portion, and an air outlet end having an outlet edge portion, each edge portion defining a periphery of the conduit, wherein the outlet edge portion of the heater chassis forms a seal with a complementary edge portion of the air duct assembly, positioned around the air outlet of the air duct assembly.

12. A fan heater according to claim 11, wherein the seal is a labyrinth seal.

13. A fan heater according to claims 11 or 12, wherein the heater element includes an air outlet side, and at least a portion of the air outlet end of the heater chassis is offset from the heater element air outlet side.

14. A fan heater according to claim 13, wherein the heater module is elongate in a direction perpendicular to the direction of airflow through the conduit, the air outlet side of the heater element is substantially planar, and the at least a portion of the air outlet end of the heater chassis is parallel to the plane of the air outlet side of the heater element.

15. A fan heater according to any of claims 11 to 14, wherein the air duct assembly comprises an exhaust chassis, positioned between the air outlet of the air duct assembly and the heater chassis, and the heater chassis is aligned with and removably connected to the exhaust chassis, such that the airflow path passes through the heater chassis and the exhaust chassis to the air outlet.

16. A fan heater according to claim 15 when ultimately dependent on claim 11, wherein the exhaust chassis includes an air inlet end having an inlet edge portion defining a periphery of the exhaust chassis, the complementary edge portion of the air duct assembly being the inlet edge portion of the exhaust chassis.

17. A fan heater according to any preceding claim, further comprising a main body, wherein the air duct assembly includes an interface portion for coupling the air duct assembly to the main body, the opening being formed in the interface portion, and the main body including an airflow generator.

18. A fan heater according to claim 17, further comprising electrical wiring, coupledto and for providing power to the heater module, the electrical wiring passing through the opening in the interface portion to a power supply in the main body.

19. A fan heater according to any preceding claim, wherein a primary direction of airflow through the heater module is perpendicular to a primary direction of airflow through the opening.

20. A heater module for use with the fan heater of any of claims 1 to 19.

21. A heater module for use with a fan heater, the heater module comprising: a two-part attachment mechanism for releasably attaching the heater module to a fan heater, wherein the two-part attachment mechanism is configured to enable a user to attach and detach the heater module via access to a first part of the two-part attachment mechanism.

22. A heater module according to claim 21, wherein the heater module is elongate, the first part of the two-part attachment mechanism is located at a first end of the heater module and a second part of the two-part attachment mechanism is located at a second end of the two-part attachment mechanism, and wherein the second part is actuated via user access to the first part.

23. A heater module according to claim 22, wherein the second part is a hook for coupling to a cantilever positioned on the fan heater.

24. A heater module according to any of claims 21 to 23 further comprising a heater chassis; a heater element supported within the heater chassis; wherein the heater chassis defines an airflow conduit having an air inlet end and an air outlet end, the air outlet end configured to form a seal with an exhaust chassis of the fan heater.

25. A heater module according to claim 24, wherein the heater module is elongate in a direction perpendicular to a direction of airflow through the conduit, the heater element includes a planar side portion configured to face the exhaust chassis, wherein at least a portion of the air outlet end forming the seal is offset from the planar side portion of the heater element.

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