GB2589615A

GB2589615A - Filter

Info

Publication number: GB2589615A
Application number: GB1917792.2A
Authority: GB
Inventors: Morris Ben
Original assignee: Global Energy Systems & Tech Ltd
Current assignee: Global Energy Systems & Tech Ltd
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2021-06-09
Also published as: GB201917792D0

Abstract

A filter module for filtering water in a central heating system comprises an inlet, an outlet, a magnetic filter medium 46 positioned between the inlet and outlet and a non-magnetic filter medium 54 positioned between the magnetic filter medium and the outlet. The filter module may comprise filter housing 4 and a removable filter component 6. The magnetic filter may pass through the centre of the filter module and be a plurality of magnets. The non-magnetic filter may be arched or curved and be a stainless steel woven mesh. The filter housing and the filter component may comprise alignment features. The filter module may be associated with a monitoring system for monitoring flow rate and indicating when it has fallen below a predetermined value.

Description

Intellectual Property Office Application No. GII1917792.2 RTM Date:21 May 2020 The following terms are registered trade marks and should be read as such wherever they occur in this document:

WRAS

Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo Filter

Technical field

The present invention relates to a filter module for filtering water in a central heating system.

Background

Central heating systems of various types are used to provide heating to residential and commercial properties. Wet systems typically involve a boiler/heat exchanger for heating water connected to radiators by a system of pipes for delivering heat to the property. Hot water therefore circulates through the system of pipes.

Dust and other particulate matter tends to gather within the system water from the boiler/heat exchanger, pipes, radiators and/or from any other components within the system. If these particles are not removed from the system water, they can cause blockages within the system and/or reduce water flow rate through the system, which can significantly reduce the efficiency of the system. This can lead to problems requiring an engineer to come out, which is both timely and costly for a user.

Such central heating systems can therefore be fitted with filters for removing particles from the system water. However, systems fitted with more simple filters tend to get clogged up very quickly, becoming ineffective as filters, leading to reduced water flow rate through the system and therefore reducing the efficiency of the central heating system. Such filters can be modified to rely on more complex techniques for filtering the water, but this makes the filters expensive to manufacture, and costly for a user to maintain and/or repair, typically requiring an engineer to come out to attend to the maintenance and/or repair.

It has been realised that many of the particles that need filtering from the system water are magnetic, since corrosion of the radiators and other components within the system leads to magnetic particles being present in the system water. Therefore, magnetic filters can be used to remove the magnetic particles from the system water. However, such filters are typically quite large and complex, requiring an engineer to come out and fit, clean and/or replace the filters when required. In addition, use of a magnetic filter only filters the magnetic particles from the system water but is ineffective against dust and other particulate matter that can also clog up the system and make the central heating system less effective.

It would therefore be desirable to provide a filter for a central heating system that overcomes one or more of the above problems. It would be desirable to provide a filter for a central heating system that is effective at removing both magnetic and nonmagnetic particles from the system water. It would be desirable to provide a filter for a central heating system that is less prone to getting blocked, and/or clogged up. It would be desirable to provide a filter for a central heating system that is easy to fit, clean and/or replace within the system, such that a user can fit, clean and/or replace the filter within the system without requiring an engineer to come out.

Summary

According to a first aspect of the present invention, there is provided a filter module for filtering water in a central heating system, the filter module comprising: an inlet for receiving water to be filtered by the filter module; an outlet for filtered water to leave the filter module; a magnetic filter medium positioned between the inlet and the outlet; and a non-magnetic filter medium positioned between the magnetic filter medium and the outlet; such that, in use, water flowing from the inlet to the outlet undergoes a first filtration by the magnetic filter medium and a second filtration by the non-magnetic filter medium.

It has been found that such a filter module is particularly effective at removing both magnetic and non-magnetic particles from the central heating system water, and the filter module is less prone to getting blocked meaning that the filter module generally lasts longer without requiring cleaning, maintenance and/or replacement. By having the two filter mediums present, and arranging the non-magnetic filter medium between the magnetic filter medium and the outlet in this way, means that the magnetic particles, which can also be larger and/or bulkier, are filtered from the water first to prevent them clogging up the non-magnetic filter medium helping the filter last longer. As such, the filter module helps the central heating system to act more efficiently and effectively for a longer time.

The use of between may be used to refer to the direction of water flow through the system. For example, the magnetic filter medium being positioned between the inlet and the outlet may mean that water flowing from the inlet to the outlet will pass the magnetic filter medium. By way of another example, the non-magnetic filter medium being positioned between the magnetic filter medium and the outlet may mean that water flowing from the magnetic filter medium to the outlet will pass the non-magnetic filter medium.

The magnetic filter medium being positioned between the inlet and the outlet may be used to mean that if a straight line was drawn from a point on the inlet to a point on the outlet, the magnetic filter medium would intersect this line. Alternatively, the magnetic filter medium being positioned between the inlet and the outlet may be used to mean that if a straight line was drawn from every point on the inlet to every point on the outlet, the magnetic filter medium would intersect all of these lines.

The non-magnetic filter medium being positioned between the magnetic filter medium and the outlet may be used to mean that if a straight line was drawn from a point on the magnetic filter medium to a point on the outlet, the non-magnetic filter medium would intersect this line. Alternatively, the non-magnetic filter medium being positioned between the magnetic filter medium and the outlet may be used to mean that if a straight line was drawn from every point on the magnetic filter medium to every point on the outlet, the non-magnetic filter medium would intersect all of these line.

The magnetic filter medium and the non-magnetic filter medium may be arranged in the filter module such that, in use, water flowing through the filter module flows from the inlet, to the magnetic filter medium, to the non-magnetic filter medium, and to the outlet.

The filter module may be substantially cylindrical. The filter module may be configured to be positioned on the return flow path in the central heating system.

The inlet may be arranged on a first side of the filter module, and the outlet may be arranged on a second side of the filter module, and the first and second sides may be opposite one another.

When the filter module is in use in a central heating system, water flowing in through the inlet may flow in a first general direction, and water flowing out through the outlet may flow in a second general direction, wherein the first general direction may be substantially parallel to the second general direction, and wherein a longitudinal axis of the magnetic filter medium may be arranged substantially perpendicular to the first and/or second general directions. The first general direction and the second general direction may be substantially aligned.

The magnetic filter medium may be arranged in the filter module in a direct flow path between the inlet and the outlet. The non-magnetic filter medium may be arranged in the filter module in a direct flow path between the inlet and the outlet and/or between the magnetic filter medium and the outlet. Having a feature in a direct flow path between two other features, may mean that the feature blocks a line of sight between the two other features. Direct may be used to mean that it is the only obstruction between two features.

The magnetic filter medium and the non-magnetic filter medium may be arranged in the filter module in a direct flow path between the inlet and the outlet.

This may make the filter mediums more effective at attracting and retaining particulate matter that may reside in the water.

Having the magnetic filter medium and the non-magnetic filter medium arranged in the filter module in a direct flow path defined between the inlet and the outlet, may comprise the magnetic filter medium and the non-magnetic filter medium at least partially blocking a line of sight between the inlet and the outlet.

Having the filter mediums positioned within the filter module in this way may mean that the filter mediums are more effective at filtering the water passing from the inlet to the outlet.

The magnetic filter medium may pass through the centre of the filter module.

Having the magnetic filter medium positioned substantially centrally within the filter module in this way may mean that the magnetic filter medium is more likely to attract the magnetic particles and therefore filter more effectively.

The filter module may define a space, and the magnetic filter medium may passes through the centre of the space.

The filter module may have a longitudinal axis, and the magnetic filter medium may be coupled to the top of the filter module in a substantially central position and may extend into the filter module towards the centre of the filter module. A longitudinal axis of the magnetic filter medium may be substantially parallel to a longitudinal axis of the filter module.

The non-magnetic filter medium may be positioned adjacent to the outlet. The non-magnetic filter medium may be positioned in front of the outlet.

The non-magnetic filter medium may be curved. This may allow the nonmagnetic filter medium to cover a larger surface area for filtering more water.

The non-magnetic filter medium may be positioned directly between the magnetic filter medium and the outlet. Direct may be used to mean that the only obstruction between the magnetic filter medium and the outlet is the non-magnetic filter medium.

The filter module may comprise a removable filter component, wherein the removable filter component may comprise the magnetic filter medium and the nonmagnetic filter medium.

The filter module may comprise a removable filter component and a filter housing for receiving the removable filter component, and the removable filter component may comprise the magnetic filter medium and the non-magnetic filter medium.

This may be highly beneficial for allowing both of the magnetic filter medium and the non-magnetic filter medium to be inserted and removed in a single step for ease of cleaning and/or maintenance of the filter module.

When the removable filter component is received by the filter housing or filter module, the magnetic filter medium and the non-magnetic filter medium may be enclosed within the filter housing or filter module respectively.

The magnetic filter medium and the non-magnetic filter medium may be releasably coupled to the removable filter module.

The removable filter component and the filter housing may have a press fit relationship.

The removable filter component may be received axially by the filter housing. When the removable filter component is received by the filter housing, the magnetic filter medium may extend axially in the filter housing. When the removable filter component is received by the filter housing, the non-magnetic filter medium may extend axially in the filter housing. In use, water may enter the filter housing through the inlet substantially radially, and water may leave the filter housing through the outlet substantially radially.

The filter housing may be substantially cylindrical. The filter housing may define the inlet and the outlet.

The filter housing may comprise at least one first aligning feature and the removable filter component may comprise at least one second aligning feature for cooperating with the at least one first aligning feature to ensure the removable filter component is received by the filter housing in a predetermined orientation.

This may provide a simple way of ensuring that the non-magnetic filter medium is positioned within the filter housing between the magnetic filter medium and the outlet so that the magnetic particles are generally filtered first allowing the filter module to last longer without getting blocked.

The filter housing may have an open end defining an inner rim, and the removable filter component may comprise a supporting portion for supporting the magnetic filter medium and the non-magnetic filter medium, and the supporting portion and the inner rim may each define a generally regular shape with at least one irregularity in the generally regular shape, and wherein the at least one irregularity in the inner rim defines the at least one first aligning feature and wherein the at least one irregularity in the supporting portion defines the at least one second aligning feature.

This may provide a simple but effective way of positioning the magnetic filter mediums in the filter housing in the desired orientation.

The removable filter component may comprise nylon. The supporting portion may comprise nylon. The removable filter component may comprise a seal for cooperating with the filter housing. The supporting portion may comprise a seal for cooperating with the filter housing.

The supporting portion and the filter housing may have a press fit relationship.

The open end may have a substantially circular cross section.

The inner rim and/or the portion of the removable filter component may each have a generally circular cross section. Each of the generally circular cross sections may have at least one portion that is generally flat to form the at least one first aligning feature and the at least one second aligning feature. The at least one first aligning feature and the at least one second aligning feature may each comprise two irregularities, which may be generally flat portions configured so that the portion of the removable filter component may only be received by the inner rim in one orientation. The irregularities may comprise a ridge or otherwise.

The filter housing may have an open end defining an inner rim, and the removable filter component may comprise a supporting portion for supporting the magnetic filter medium and the non-magnetic filter medium, and wherein the supporting portion and the inner rim may define shapes that cooperate in only one relative orientation to ensure the removable filter component is received by the filter module in a predetermined orientation. The inner rim may comprise the at least one first aligning feature and the supporting portion may comprise the at least one second aligning feature. The shapes may be substantially circular in cross section.

The filter housing and the removable filter component may have a press fit relationship. This may provide a very simple and convenient mechanism for retrieving the removable filter component, and therefore magnetic and non-magnetic filter mediums, from the filter housing. The supporting portion and the filter housing may have a press fit relationship.

The removable filter component may comprise gripping means that are arranged on the removable filter component to be accessible from outside the filter module when the removable filter component is received by the filter housing, and the filter module may be associated with fixing means, wherein the gripping means may be configured to releasably couple with the fixing means for retrieving the removable filter component from the filter housing.

The gripping means may comprise an aperture and the fixing means may be elongate, the aperture defining a shape that cooperates with a shape of the fixing means. The supporting portion may comprise the gripping means. The aperture may be defined in the supporting portion. The aperture may be defined in a top surface of the supporting portion. The aperture may be a blind hole. The fixing means may be a fastener. The fixing means may be a screw. The gripping means may comprise an aperture having screw threads on its radial surface, and the fixing means may have cooperating screw threads. The fixing means or screw may therefore be screwed into place in the aperture to couple the fixing means and gripping means so that the removable component can be easily retrieved, for example pulled out, from the filter housing.

The filter module may comprise a cover for the filter housing, wherein the filter housing may receive the removable filter component to enclose the magnetic filter medium and the non-magnetic filter medium within the filter housing, and wherein the cover may be received by the filter housing to enclose the removable filter component within the filter housing, the cover providing a seal for the filter module.

This may provide for more flexibility in the configuration and materials used for the removable filter component since it does not need to provide the seal. The removable filter component and cover can therefore be designed and configured to be more effective at their particular functions. Additionally or alternatively, this may help provide for a more secure and/or effective seal by having both of the removable filter component and cover to provide effective lids for the open end of the filter housing.

The filter module may comprise a cover for the filter housing, wherein the filter housing may receive the removable filter component to enclose the magnetic filter medium and the non-magnetic filter medium within the filter housing, and wherein the cover may be received by the filter housing to enclose the removable filter component within the filter housing, the cover comprising a seal for cooperating with the filter housing, and optionally, the removable filter component and/or supporting portion.

The cover may releasably couple to the filter housing. The seal may be substantially watertight. The seal may cooperate with the filter housing and the removable filter component.

The cover may comprise a gasket for cooperating with the filter housing and the removable filter component. The cover may comprise a nut. The nut may comprise a closed upper end. The gasket may be fitted on an inside of the closed upper end. The gasket may have a substantially circular cross section. The gasket may comprise one or more rubber seals. The rubber may comprise EDPM.

The filter housing and the cover may be configured to couple by relative rotation between the cover and the filter housing. The filter housing and the cover may comprise cooperating threads for coupling the cover and the filter housing. The filter housing may have an external screw thread that cooperates with an internal screw thread on the cover to screw the cover in place on the filter housing. This may provide a convenient way of a user securing the cover in place on the filter housing to seal the filter module.

The filter module may be associated with releasing means specially adapted, adapted or configured, to cooperate with the cover, and the releasing means may be configured to secure the cover to the filter housing when operated in a first manner and to release the cover from the filter housing when operated in a second manner.

The releasing means may have an aperture, the aperture defining a shape that cooperates with a shape defined by the cover, and the first manner may be rotating the releasing means clockwise or anticlockwise on the cover, and the second manner may be rotating the releasing means the anticlockwise or clockwise respectively on the cover. The releasing means may be a ring spanner. The ring spanner may be configured to cooperate with the nut of the cover. Rotating the releasing means on the cover may rotate the cover with the releasing means. The releasing means may have a handle portion. This may allow for easier rotation of the cover for securing or releasing the cover from the filter housing.

The removable filter component and the filter housing may be configured to have a press fit relationship, and the filter housing and the cover may be configured to couple by relative rotation between the cover and the filter housing.

This may provide a particularly convenient way of assembling and disassembling the filter module to ensure that the filter mediums are in the desired orientation and that the filter module is sealed.

When the filter module is in use in the central heating system, the filter housing may define the inlet on a first side, the filter housing may define the outlet on a second side opposite the first side, and wherein the removable filter component may be received through a top surface of the filter housing and the cover may be received by the top surface of the filter housing.

This may help allow for a filter module requiring less sealing without leaking.

This may also help provide for a useful tolerance, for accounting for any error in user operation, for example if a user doesn't screw the cover on tightly enough.

The magnetic filter medium may be configured to attract and retain magnetic particles from the system water in the medium, for example metallic particles and/or ferromagnetic particles.

The magnetic filter medium may comprise one or more magnets. The one or more magnets may comprise two magnets. The one or more magnets may be permanent magnets. The one or more magnets may be elongate. Where the one or more magnets are elongate, the longitudinal axis of the magnets may be arranged in the filter module to be substantially parallel to a longitudinal axis of the filter module and/or the filter housing. The magnetic filter medium may be releasably coupled to the removable filter module. The magnetic filter medium may comprise a magnet housing for enclosing the one or more magnets and the magnet housing may be releasably coupled to the removable filter module.

The non-magnetic filter medium may comprise a mesh. The mesh may comprise wire. The non-magnetic filter medium may comprise a frame and a mesh releasably coupled to the frame. The non-magnetic filter medium and/or the frame and/or the mesh may comprise stainless steel. The frame may comprise tabs for releasably coupling the mesh to the frame. The non-magnetic filter medium may be releasably coupled to the removable filter module. The tabs may be flexible and/or resilient.

The non-magnetic filter medium may be configured to attract and retain particulate matter from the system water in the medium, for example metallic and/or non-magnetic particles.

The filter module may be associated with a monitoring system for monitoring flow rate in the central heating system, wherein the monitoring system may comprise a sensor for measuring the flow rate, and an indicator for indicating when the flow rate has fallen to or below a pre-determined value. The pre-determined value may be a lower threshold value.

This may provide for a convenient way of making the user aware when they may need to clean the filter module and/or when there may be a problem with the filter module and/or central heating system.

The monitoring system may comprise a processor for processing the measured flow rate and comparing it to the pre-determined value to determine whether the flow rate has fallen to or below the pre-determined value.

The sensor may be positioned adjacent to, or within, a heat pump of the central heating system.

The indicator may be positioned within the central heating system, for example so a user of the central heating system can view the indicator. The indicator may be positioned remotely, for example in a central control room where the function of the central heating system is monitored with others. The indicator may comprise a display.

The monitoring system may comprise an alarm for alerting a user when the flow rate has fallen below the pre-determined value.

There is provided a filter module for filtering water in a central heating system, the filter module comprising: a filter housing having an open end for receiving a removable filter component, the filter housing defining: an inlet for receiving water to be filtered by the filter module; and an outlet for filtered water to leave the filter module; and the removable filter component configured to be received by the open end of the filter housing, the removable filter component comprising: a magnetic filter medium; and a non-magnetic filter medium; wherein when the removable filter component is received by the filter housing, the magnetic filter medium is positioned between the inlet and the outlet, and the non-magnetic filter medium is positioned between the magnetic filter medium and the outlet, such that, in use, water flowing from the inlet to the outlet undergoes a first filtration by the magnetic filter medium and a second filtration by the non-magnetic filter medium. The open end may be configured to receive the removable filter component in a single, predetermined orientation. The open end may comprise at least one first aligning feature for cooperating with at least one second aligning feature on the removable filter component such that the removable filter component can only be received by the filter housing in a predetermined orientation.

The filter module may further comprise a cover for releasably coupling with the filter housing to secure the removable filter component in the filter housing when the removable filter component is received by the filter housing, the cover providing a seal for the filter module. The removable filter component and the filter housing may be configured with a press-fit relationship, and the cover and the filter housing may couple by relative rotation between the cover and the filter housing.

There is provided a filter module for filtering water in a central heating system, the filter module comprising: (a) a filter housing having an open end for receiving a removable filter component, the filter housing defining: an inlet for receiving water to be filtered by the filter module; and an outlet for filtered water to leave the filter module; and (b) the removable filter component configured to be received by the open end of the filter housing, the removable filter component comprising: a magnetic filter medium; a non-magnetic filter medium; wherein when the removable filter component is received by the filter housing, the magnetic filter medium is positioned between the inlet and the outlet, and the non-magnetic filter medium is positioned between the magnetic filter medium and the outlet, such that, in use, water flowing from the inlet to the outlet undergoes a first filtration by the magnetic filter medium and a second filtration by the non-magnetic filter medium; and (c) a cover for releasably coupling with the filter housing to secure the removable filter component in the filter housing when the removable filter component is received by the filter housing, the cover providing a seal for the filter module.

There is provided a filter assembly for a central heating system, comprising: (i) a filter module for filtering water in a central heating system, the filter module comprising: (a) a filter housing having an open end for receiving a removable filter component, the filter housing defining: an inlet for receiving water to be filtered by the filter module; and an outlet for filtered water to leave the filter module; and (b) the removable filter component configured to be received by the open end of the filter housing, the removable filter component comprising: a magnetic filter medium; a non-magnetic filter medium; wherein when the removable filter component is received by the filter housing, the magnetic filter medium is positioned between the inlet and the outlet, and the non-magnetic filter medium is positioned between the magnetic filter medium and the outlet, such that, in use, water flowing from the inlet to the outlet undergoes a first filtration by the magnetic filter medium and a second filtration by the non-magnetic filter medium; and (c) a cover for releasably coupling with the filter housing to secure the removable filter component in the filter housing when the removable filter component is received by the filter housing, the cover providing a seal for the filter module; (ii) two valves, a first for placing in the central heating system before the inlet and a second for placing in the central heating system after the outlet; (iii) releasing means specially adapted to cooperate with the cover, the releasing means being configured to secure the cover to the filter housing when operated in a first manner and to release the cover from the filter housing when operated in a second manner; and (iv) fixing means configured to releasably couple with the removable filter component for retrieving the removable filter component from the filter housing when the removable filter component is received by the filter housing.

The filter assembly may further comprise a heat pump for the central heating system.

Any feature(s) described herein in relation to one aspect, embodiment, example or otherwise, may be combined with any other feature(s) described herein in relation to any other aspect, embodiment, example or otherwise, as appropriate and applicable.

Brief description of the drawings

The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labelled in every drawing. Unless indicated otherwise, arrows in the figures are used to show the intended direction of water flow. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of an assembled water filter for a central heating system in accordance with an embodiment; Figure 2 shows a perspective view of an assembled water filter for a central heating system installed in a central heating system, with a releasing means and two fixing means present; Figure 3 shows an exploded view of at least a part of a water filter assembly for a central heating system including a water filter for a central heating system; Figure 4 shows a perceptive view of the disassembled parts of a water filter for a central heating system; Figure 5 shows an alternative perspective view to figure 4; Figure 6 shows a perspective view of a filter housing of a water filter for a central heating system; Figure 7 shows an alternative perspective view to figure 6; Figure 8 shows a near top view of a filter housing of a water filter for a central heating system; Figure 9 shows a perspective view of a removable filter component for a water filter for a central heating system, the removable filter component comprising a magnetic filter medium and a non-magnetic filter medium; Figure 10 shows another perspective view of a removable filter component for a water filter for a central heating system, the removable filter component comprising a magnetic filter medium and a non-magnetic filter medium; Figure 11 shows another perspective view of a removable filter component for a water filter for a central heating system, the removable filter component comprising a magnetic filter medium and a non-magnetic filter medium; Figure 12 shows a perspective view of a cover for a water filter for a central heating system; Figure 13 shows another perspective view of a cover for a water filter for a central heating system; Figure 14 shows various steps that may be taken to clean the filter mediums of a water filter for a central heating system when the water filter is installed in the central heating system; Figure 15 shows a perspective view of various parts of a water filter assembly for a central heating system including a partially disassembled water filter for a central heating system; Figure 16a illustrates one upright orientation for a water filter for a central heating system within the central heating system, and figure 16b shows an alternative side-on orientation for a water filter for a central heating system within the central heating system.

Detailed description

Aspects and embodiments disclosed herein are not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Aspects and embodiments disclosed herein are capable of being practiced or of being carried out in various ways.

Referring to the figures, there is shown a water filter 2, or filter module, for a central heating system. A wet central heating system typically comprises a boiler or heat exchanger for heating water. The boiler or heat exchanger is connected to one or more radiators by a system of pipes, the radiators for delivering heat to the surroundings. The boiler or heat exchanger therefore heats the water and the hot water circulates around the system through the pipes. This water then returns to the boiler or heat exchanger on a return path to be re-heated by the boiler or heat exchanger and then re-circulated around the system. Such a water filter as described herein is typically placed on this return path, after the hot water has passed through the radiators and pipes, and before the water re-enters into the boiler or heat exchanger. This is to ensure that the water is filtered immediately before entering the boiler or heat exchanger to prevent particulate matter clogging up the various components of the boiler or heat exchanger, for instance the air source heat pump, which would cause inefficiencies in, and/or problems for, the central heating system. It is possible that the filter could be placed elsewhere in the system. The water filter is typically placed between two shut-off valves, for instance gate valves, for stopping/starting the water flow between the two valves.

The water filter 2 may comprise a filter housing 4 or main body, a removable filter component 6 to be received by the filter housing, and a cover 8 or cap for the filter housing.

The filter housing 4 has a lower end 4a, an upper end 4b, a water inlet 5 and a water outlet 7. The water inlet 5 and the water outlet 7 may be positioned on opposing sides of the filter housing 4. The filter housing 4 may comprise a substantially cylindrical pipe 10 or tube that is fitted with a base plate 12 on its lower end 4a, and two pipe portions or welding nipples 14a, 14b connected to through holes on opposing sides of the housing's cylindrical surface 16. The welding nipples 14a, 14b are for connecting to a water pipe of a central heating system, particularly to two shut-off valves 18a, 18b, for instance gate valves, connected to the water pipe. The welding nipples 14a, 14b may therefore provide the water inlet 5 and water outlet 7 of the filter housing 4 respectively.

The upper end 4b of the filter housing 4 may be open, providing an open end 20 for receiving the removable filter component 6, the open end 20 defining a rim 22.

Providing the upper end 4b of the filter housing 4 with the open end 20 may mean that when the water filter 2 is fitted into a central heating system in this orientation, leaking is less likely. An inner surface 24 of the filter housing 4 defines a ledge 26 or seat for supporting the removable filter component 6 therein. The seat may be stepped. The upper end 4b of the filter housing 4 extending from the rim 22 may have an external thread 28 for cooperating with an internal thread 30 on the cover 8. It will be appreciated from the above and the figures that the filter housing 4 may have a substantially cross shaped cross section and may be hollow.

The filter housing 4 may comprise one or more first aligning features 32 for cooperating with one or more second aligning features 34 on the removable filter component 6 to ensure that the filter housing 4 receives the filter component 6 in the desired orientation.

The rim 22 may define a generally regular shaped cross section, for instance a substantially circular cross section, but with one or more irregularities 36 in the otherwise generally regular shaped cross section, for instance one or more flat portions 36 in the otherwise substantially circular cross section. There may be two irregularities 36 on radially opposing sides of the rim 22, with slightly different shapes or orientations. The one or more first aligning features 32 may be provided by the one or more irregularities 36.

The filter housing 4 may comprise stainless steel, for instance 316 stainless steel. The through holes and welding nipples 14a, 14b may typically be approximately 28mm in diameter to cooperate with standard central heating pipework.

The removable filter component 6 may be received axially by the filter housing 4, in particular through the open end 20. The removable filter component 6 may comprise a magnetic filter medium 40 and a non-magnetic filter medium 42. This allows both of the magnetic filter medium 40 and the non-magnetic filter medium 42 to be removed from the filter housing 4 in one step, for ease of cleaning ancVor replacement of one or both of the magnetic filter medium 40 and the non-magnetic filter medium 42. The magnetic filter medium 40 and the non-magnetic filter medium 42 may be detachable from the removable filter component 6.

The removable filter component 6 may comprise a supporting portion 38 for supporting both the magnetic filter medium 40 and the non-magnetic filter medium 42. The supporting portion 38 may be substantially plate-like. The supporting portion 38 may cooperate with the open end 20 and rim 22 to close off the open end 20. The supporting portion 38 may sit on the ledge 26. In this way, the supporting portion 38 may form an intermediate lid for the filter housing 4, between the filter housing 4 and the cover 8. The supporting portion 38 may comprise nylon, for example Nylon 66. As mentioned above, the removable filter component 6, in particular the supporting portion 38, may comprise one or more second aligning features 34 for cooperating with the one or more first aligning features 32. The supporting portion 38 may define a shape that substantially cooperates and/or matches a shape defined by the rim 22. The supporting portion 38 may be press fit into the open end 20. The supporting portion 38 may have a generally regular shaped cross section, for instance a substantially circular cross section, but with one or more irregularities 44 in the otherwise generally regular shaped cross section, for instance one or more flat portions in the otherwise substantially circular cross section. There may be two irregularities 44 on radially opposing sides of the supporting portion 38, which may have slightly different shapes or orientations. The one or more second aligning features 34 may be provided by the one or more irregularities 44.

The supporting portion 38 may comprise first means for supporting the magnetic filter medium 40 thereon. Any suitable cooperating and/or fastening features on the supporting portion 38 and/or magnetic filter medium 40 may be used. The supporting portion 38 may comprise one or more first blind holes 45 open to its underside, and the one or more first blind holes 45 may have a threaded radial surface.

The magnetic filter medium 40 may comprise a magnet housing 46 and at least one magnet within the housing 46. The magnet housing may comprise Nylon, for example Nylon 66. The magnet housing 46 may be substantially test tube shaped for enclosing the at least one magnet therein between the magnet housing 46 and the supporting portion 38, for example for enclosing two torpedo magnets (for example two 5mm dia x 30mmA -N42 -NiCuNi plated NdFeB rod magnets). The open end of the test tube shape may cooperate with the underside of the supporting portion 38. An upper end of the magnet housing 46 cooperates one of the first blind holes 45. An upper end of the magnet housing 46 may have an external thread for cooperating with the threaded surface one of the first blind holes 45. This allows the at least one magnet to be placed in the magnet housing 46 and the magnet housing 46 to be screwed into the first blind hole 45. The one or more first blind holes 45 may be positioned substantially centrally on the supporting portion 38 for supporting the magnetic filter medium 40 substantially centrally within the filter housing 4.

The supporting portion 38 may further comprise second means for supporting the non-magnetic filter medium 42 thereon. Any suitable cooperating and/or fastening features on the supporting portion 38 and/or non-magnetic filter medium 42 may be used. The supporting portion 38 may comprise one or more second blind holes 48, 50 open to its underside. The non-magnetic filter medium 42 may comprise a mesh 54, for instance a gauze, and a frame 52 for supporting the mesh 54. The mesh 54 may for example be a stainless steel 304 woven mesh, and for instance may be a 40 by 40 mesh, having a wire size of approximately 0.224mm. The frame 52 may have tabs 56 to secure the mesh 54 in place on the frame. The tabs 56 may be flexible to bend over the mesh 54 as shown, which may make it easy to replace the mesh 54 if/when required. The frame 52 may comprise one or more securing portions 58 for cooperating with the one or more second blind holes 48, 50 to hold the frame 52 and mesh 54 in place on the supporting portion 38. The one or more securing portions 58 may be resilient so that the one or more securing portions 58 may be bent for being inserted into the one or more second blind holes 48, 50, and then released to spring back out to cooperate with the one or more second blind holes 48, 50 to be retained by the one or more second blind holes 48, 50. The one or more second blind holes 48, 50 may be positioned radially outwards from the centre of the supporting portion 38, perhaps adjacent an edge of the supporting portion 38 so that the non-magnetic filter medium 42 can be positioned just in front of the outlet 7 in the direction of water flow from the inlet 5 to the outlet 7. This may maximise the water's exposure to the non-magnetic filter medium 42 to provide for more effective filtering.

The non-magnetic filter medium 42 may have a shape that follows the shape defined by the supporting portion 38, and therefore also the open end 20 and filter housing 4. For example, the filter housing 4 and open end 20 may be substantially cylindrical and/or may have a substantially circular cross section. The supporting portion 38 may therefore have a substantially circular cross section. The non-magnetic filter medium 42 may be arched or curved and may follow the shape of the supporting portion 38 and/or the shape of the filter housing 4. Having the non-magnetic filter medium 42 follow the shape of the filter housing 4 and/or arching or curving the nonmagnetic filter medium 42 may maximise the surface area covered by the non- magnetic filter medium 42 which may maximise the water's exposure to the non-magnetic filter medium 42 to provide for more effective filtering.

The supporting portion 38 may further comprise gripping means 72 for gripping the supporting portion 38 and therefore retrieving the supporting portion 38 and removable filter component 6 from the filter housing 4. Any suitable means may be used. For example, the supporting portion may comprise one or more blind holes 74 open to its topside, and the one or more blind holes 74 may have a threaded radial surface. The threaded surface may be for cooperating with one or more fixing means 76 for fixing in place in the one or more blind holes 74. The fixing means 76 may be screws and the screws may be screwed into the blind holes 74 to cooperate with the thread in the blind holes 74 so that pulling on the screws pulls the supporting portion 38 and therefore the removable filter component 6 out of the filter housing 4. This is advantageous where the supporting portion 38 and filter housing 4 have a press fit relationship.

The cover 8 may cooperate with the filter housing 4 to provide a seal, in particular a substantially watertight seal, for the water filter 2. The cover 8 may comprise or be in the shape of a nut 60 with one closed upper end 62. The cover 8 may comprise an internal thread 30 for cooperating with an external thread 28 on the filter housing 4 to provide a lid for the filter housing 4 and to enclose the filter component 6 within the filter housing 4. This may allow the cover 8 to be easily screwed onto the filter housing 4 when the removable filter component 6 is inserted into the filter housing 4 to secure the removable filter component 6 in place in the filter housing 4 and to prevent water flowing through the water filter 2 from leaking out. The cover 8 may comprise a gasket 64 which may cooperate with the supporting portion 38 of the filter component 6. The gasket 64 may be fitted on the inside of the one closed upper end 62. The gasket 64 may have a substantially circular cross section. The gasket 64 may comprise one or more rubber seals. The rubber may comprise EDPM (ethylene propylene diene monomer) rubber, for instance WRAS EPDM and/or standard EPDM sample. The WRAS EPDM may have a cloth finish and/or the standard EPDM may have a matt finish. The material for the gasket may be resilient which may allow it to be compressed against the supporting portion 38 and rim 22 when screwed in place on the filter housing 4, and may allow it to spring back to its original shape when unscrewed so that an effective seal is achieved every time the cover 8 is unscrewed and screwed back onto the filter housing 4. For example, this may mean that the material for the gasket 64 is selected such that it has no memory properties, for better re-sealing when the cover 8 is unscrewed from the filter housing 4 and then re-screwed back on.

There may also be provided a releasing means 66 for cooperating with the cover 8 for easy removal of the cover 8 from the filter housing 4. For example, where the cover is in the shape of a nut 60, the releasing means 66 may be a spanner or wrench, or for instance a ring spanner, having an opening 68 that cooperates with the nut 60. The cover 8 may have a substantially hexagonal cross section and the opening 68 defined by the ring spanner 66 may have a cooperating substantially hexagonal cross section. The releasing means 66 may have a handle portion 69 for a user to grip. The releasing means 66 may also comprise one or more holding or retaining portions 70 for holding the one or more fixing means 76 when the one or more fixing means 76 are not being used. Where the one or more fixing means 76 are screws, the one or more holding portions 70 may just comprise through holes 78 for holding the screws in place. The water filter 2 may be part of a water filter assembly 1000 and the water filter assembly 1000 may comprise the releasing means 66 and/or the one or more fixing means 76.

The water filter 2, the two shut-off valves 18a, 18b, the releasing means 66, and the one or more fixing means 76 may be provided as a kit for connecting to an existing central heating system. The water filter assembly 1000 may comprise the water filter 2, the two shut-off valves 18a, 18b, the releasing means 66, and the one or more fixing means 76.

The water filter 2 may be associated with, and/or the central heating system may comprise, a monitoring system. The monitoring system may comprise a sensor for monitoring water flow through the system. In some cases, the central heating system may comprise, and/or the water filter 2 may be associated with, a heat pump, for example an air source heat pump, and the sensor may be configured to monitor water flow rate through the system. The water flow rate can be monitored on site or remotely. For example, there may a display or dial associated with the monitoring system so that a user can read the water flow rate at any time. The water flow rate may be sent to a remote server where the data can be monitored remotely. The monitoring system may be associated with a predetermined lower threshold value for the water flow rate, depending on the particular system and/or heat pump. The monitoring system may comprise, or the water filter 2 may be associated with, a processor for processing the measured flow rate and comparing it to the pre-determined lower threshold value to determine whether the flow rate has fallen to or below the pre-determined value. The monitoring system may comprise, or the water filter 2 may be associated with, an alarm or alerting means to alert the user when the flow rate has fallen to or below the predetermined value.

When the water flow rate falls to this predetermined threshold value, the water filter 2 should be disassembled and the magnetic filter medium 40 and/or non-magnetic filter medium 42 cleaned. If the filter mediums 40, 42 are clogged up and in need of a clean, cleaning them should cause the water flow rate to increase back to a more normal and/or expected value. By way of example, for an existing Caernarfon 18kW Eco Air Source Heat Pump, this threshold value may be approximately 14.5-17.5 litres per minute. By way of another example, for other existing heat pumps, this threshold value may be approximately 5.5-8.5 litres per minute. The pre-determined threshold value may be an associated minimum flow rate, at which point the monitoring system or sensor or a processor may activate and/or trigger an alarm identifying a potentially blocked filter.

The water filter 2, the two shut-off valves 18a, 18b, the releasing means 66, the one or more fixing means 76, the heat pump and the sensor, and/or any combination of these components may be provided as a kit for connecting to an existing central heating system. The water filter assembly 1000 may comprise the water filter 2, the two shut-off valves 18a, 18b, the releasing means 66, the one or more fixing means 76, the heat pump and the sensor, and/or any combination of these components.

In use, there is provided a water filter 2. There may also be provided two shut-off valves 18a, 18b, a releasing means 66, and one or more fixing means 76. The water filter 2 may be fitted to a central heating system. As mentioned above, such a water filter 2 is typically placed on the return path to the boiler or heat exchanger, and so after the hot water has passed through the radiators and pipes, and before the water re-enters into the boiler or heat exchanger. Two shut-off valves 18a, 18b may be incorporated into the pipework of the central heating system. The water filter 2 is typically placed between the two shut-off valves 18a, 18b, for instance gate valves, for stopping/starting the water flow between the two valves 18a, 18b. Two connectors or adapters may be used to connect the inlet 5 and outlet 7 of the filter housing 4 to two pipe sections 82a, 82b, and so to position the filter housing 4 between the two pipe sections 82a, 82b, and so between the two shut-off valves, on the return path within the central heating system.

The water filter 2 may be positioned within the central heating system in an assembled state and so with all parts of the water filter 2 in place, or the water filter 2 may be positioned within the central heating system in a dis-assembled state and so with only the filter housing 4 in place. When the water filter 2 is positioned within the central heating in the dissembled state, the other components of the water filter 2 are then assembled with the filter housing 4 whilst it is connected to the central heating system.

To assemble the removable filter component 6, the magnetic filter medium 40 is connected to the supporting portion 38, in particular its underside. For example, the at least one magnet is placed within the magnet housing 46 and then the magnet housing 46 is screwed into place in a first blind hole 45. In addition, the non-magnetic filter medium 42 is connected to the supporting portion 38, in particular the underside. For example, the mesh 54 is connected to the frame 52, for instance using the tabs 56 where present, and then the one or more securing portions 58 are inserted into the one or more second blind holes 48, 50 to flex into place. The removable filter component 6 is now assembled with both the magnetic filter medium 40 and the non-magnetic filter medium 42 connected to it.

Once the filter housing 4 is connected to the pipe sections 82a, 82b, and so between the two shut-off valves 18a, 18b, the removable filter component 6 can be inserted into the filter housing 4. If the filter housing 4 is not connected as such within the central heating system, the removable filter component 6 can of course still be inserted into the filter housing 4. To do so, the one or more first aligning features 32 and the one or more second aligning features 34 are aligned, since the removable filter component 6 may only be to be inserted into the filter housing 4 when they are aligned. This may be to ensure that the removable filter component 6 is inserted into the filter housing 4 in the correct or desired orientation, with the non-magnetic filter medium 42 positioned between the magnetic filter medium 40 and the outlet 7, and with the non-magnetic filter medium 42 in the correct orientation. Once aligned, the supporting portion 38 may be inserted axially through the open end 20 of the filter housing with the magnetic filter medium 40 and the non-magnetic filter medium 42 connected to its underside, being press fit into the open end 20 to enclose the magnetic filter medium 40 and the non-magnetic filter medium 42 within the filter housing 4 and the supporting portion 38. The supporting portion 38 cooperates with the ledge 26 on the inner surface 24 of the filter housing 4 to prevent the removable filter component 6 being inserted too far into the filter housing 4.

Once assembled, there may be a direct flow path defined between the inlet 5 and the outlet 7. A direct flow path may be defined by a straight line path and/or line of sight between the inlet 5 and the outlet 7. For instance, the direct flow path may follow the shortest route between the inlet 5 and the outlet 7. A direct flow path may be used to mean that no obstructions lie between the two features defining the direct flow path. The magnetic filter medium 40 and the non-magnetic filter medium 42 may be arranged on the supporting portion 38, and the removable filter component 6 may be arranged in the water filter 2, such that one or both of the magnetic filter medium 40 and the non-magnetic filter medium 42 are in the direct flow path between the inlet 5 and the outlet 7.

The cover 8 may then be coupled to the filter housing 4, when the removable filter component 6 has been received by, and so inserted into, the filter housing 4. For example, the cover 8 may be simply screwed onto the top of the filter housing 4 using the cooperating threads 28, 30 on the filter housing 4 and cover 8. In doing so, the gasket 64 presses against the supporting portion 38 and the rim 22 to provide a seal for the water filter 2.

When the water filter 2 is positioned and assembled within the central heating system, the two shut-off valves 18a, 18b can be opened to allow water to flow through the water filter 2 from the inlet 5 to the outlet 7. Water enters the inlet 5 and passes over the magnetic filter medium 40 to undergo a first filtration whereby magnetic particles within the water are attracted to the magnetic filter medium 40. Where the magnetic filter medium 40 is in the direct flow path between the inlet 5 and outlet 7, the magnetic particles may be more likely to be attracted to the magnetic filter medium 40 and so filtered from the water. It may also allow for the use of weaker magnets which may reduce manufacturing costs. After passing over the magnetic filter medium 40, the water flows through the non-magnetic filter medium 42 to undergo a second filtration whereby any particulate matter in the water. It is beneficial to have the filter mediums 40, 42 arranged in this way, so that the magnetic filtration takes place before the non-magnetic filtration, since there tends to be a lot of magnetic particles within the water of central heating systems and so the non-magnetic medium 42 would otherwise get clogged up too quickly. The magnetic particles may also be larger and/or bulkier. The filtered water then passes to the outlet 7.

A user may decide to clean the water filter 2 from time to time and/or when they believe they notice an inefficiency in the central heating system. Where a monitoring system is associated with the central heating system and/or the water filter 2, the user may be alerted to the water flow rate having reduced to a lower threshold value which may prompt them to check and/or clean the water filter 2.

To clean the water filter 2, the user may simply uncouple the cover 8 from the filter housing 4. For example, the user may unscrew the cover 8 from the filter housing 4. Where present, this can be performed using the releasing means 66 for cooperating with the cover 8 for easy removal of the cover 8 from the filter housing 4. The removable filter component 6 can then be uncoupled, removed from and/or pulled out of the filter housing 4. Where present, the one or more fixing means 76 can be used to cooperate with the gripping means 72 to be able to easily pull the removable filter component 6 from out of the filter housing 4. For example, the user may screw the screws 76 into the blind holes 74 so that their threads cooperate and then may pull on the screws 76 once secured in the blind holes 74 to pull the removable filter component 6 from out of the filter housing 4. It should be noted that there may only be one blind hole 74 and one screw 76.

The user can then simply clean the magnetic filter medium 40 and the nonmagnetic filter medium 42. For example, the non-magnetic filter medium 42 or mesh 54 or frame 52 may be wiped with a cloth to remove any loose particles from the non-magnetic filter medium 42 or mesh 54. Once wiped with a cloth, or alternatively, the non-magnetic filter medium 42 or mesh 54 or frame 52 may be washed with water, perhaps under a tap, to remove any further particles or dirt that wasn't removable by the cloth. The magnetic filter medium 40 or magnet housing 46 may be wiped with a cloth to remove any loose magnetic particles attached thereto. Once wiped with a cloth, or alternatively, the magnetic filter medium 40 or magnet housing 46 may be washed with water, perhaps under a tap, to remove any further particles, magnetic or otherwise, or dirt, that wasn't removable by the cloth.

If replacement of either the magnetic filter medium 40 or the non-magnetic filter medium 42 is required, the user can also easily attend to this, either by replacing the one or more magnets, the magnet housing, and/or the frame 52 and/or mesh 54.

The water filter 2 is then re-assembled as has already been described above.

Figure 14 outlines an example of various steps that may be taken to clean the filter mediums 40, 42 of a water filter 2 for a central heating system when the water filter 2 is installed in the central heating system, which may reiterate one or more steps mentioned above. Step i) shows the water filter 2 in a working position, in the orientation in which it may be installed in a central heating system, and the arrow indicates this direction of water flow through the system. Step ii) involves closing the shut-off valves 18a, 18b which are positioned either side of the water filter 2, the dotted lines showing the position of the levers of the shut-off valves 18a, 18b before being turned and therefore when in the open position. Step iii) involves using a spanner 66 to release and therefore remove the cover 8 from the filter housing 4. In this example, the cover 8 is slackened by turning the spanner 66 in an anti-clockwise direction. Step iv) involves removing the removable filter component 6 from the filter housing 4 using the spanner 66 and screws 76. The screws 76 engage in screw threaded blind holes 74 in a top side of the supporting portion 38 to allow the removable filter component 6 to be pulled out of the filter housing 4. Step v) involves removing debris from the nonmagnetic filter medium 42, in particular the mesh 54. To re-assemble the water filter 2, the removable filter component 6 may be pushed back into the filter housing 4. The user should ensure that the removable filter component 6 is fully seated in the filter housing 4, for example sitting on the ledge 26, before coupling the cover 8 to the filter housing 4.

Figures 16a and 16b show two orientations for the water filter 2 in the central heating system. Figure 16a shows an upright configuration wherein, in use, the cover 8 is coupled to the filter housing 4 on its uppermost surface. This may be a desirable configuration as an additional security against leaking. Figure 16b shows a side-on configuration wherein, in use, the inlet 5 is on the uppermost surface of the filter housing 4.

It will be appreciated from the above description of the water filter 2 or filter module, that the filter module: is effective at removing both magnetic and non-magnetic particles from the system water; is less prone to getting blocked, and/or clogged up; and is easy to fit, clean and/or replace within the system, such that a user can fit, clean and/or replace the filter within the system without requiring an engineer to come out.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the appended claims.

Claims

Claims 1. A filter module for filtering water in a central heating system, the filter module comprising: an inlet for receiving water to be filtered by the filter module; an outlet for filtered water to leave the filter module; a magnetic filter medium positioned between the inlet and the outlet; and a non-magnetic filter medium positioned between the magnetic filter medium and the outlet; such that, in use, water flowing from the inlet to the outlet undergoes a first filtration by the magnetic filter medium and a second filtration by the non-magnetic filter medium 2. The filter module as claimed in claim 1, wherein the magnetic filter medium and the non-magnetic filter medium are arranged in the filter module in a direct flow path between the inlet and the outlet.3. The filter module as claimed in claim 2, wherein having the magnetic filter medium and the non-magnetic filter medium arranged in the filter module in a direct flow path defined between the inlet and the outlet, comprises the magnetic filter medium and the non-magnetic filter medium at least partially blocking a line of sight between the inlet and the outlet.4. The filter module as claimed in either one of claims 2 or 3, wherein the magnetic filter medium passes through the centre of the filter module.5. The filter module as claimed in any preceding claim, wherein the filter module comprises a removable filter component and a filter housing for receiving the removable filter component, and wherein the removable filter component comprises the magnetic filter medium and the non-magnetic filter medium.6. The filter module as claimed in claim 5, wherein the filter housing comprises at least one first aligning feature and the removable filter component comprises at least one second aligning feature for cooperating with the at least one first aligning feature to ensure the removable filter component is received by the filter housing in a predetermined orientation.7. The filter module as claimed in either of claims 5 or 6, wherein the filter housing has an open end defining an inner rim, and wherein the removable filter component comprises a supporting portion for supporting the magnetic filter medium and the nonmagnetic filter medium, and wherein the supporting portion and the inner rim each define a generally regular shape with at least one irregularity in the generally regular shape, and wherein the at least one irregularity in the inner rim defines the at least one first aligning feature and wherein the at least one irregularity in the supporting portion defines the at least one second aligning feature.8. The filter module as claimed in any of claims 5 to 7, wherein the filter housing and the removable filter component have a press fit relationship.9. The filter module as claimed in any of claims 5 to 8, wherein the removable filter component comprises gripping means that are arranged on the removable filter component to be accessible from outside the filter module when the removable filter component is received by the filter housing, wherein the filter module is associated with fixing means, and wherein the gripping means is configured to releasably couple with the fixing means for retrieving the removable filter component from the filter housing.10. The filter module as claimed in any of claims 5 to 9, wherein the filter module comprises a cover for the filter housing, wherein the filter housing receives the removable filter component to enclose the magnetic filter medium and the nonmagnetic filter medium within the filter housing, and wherein the cover is received by the filter housing to enclose the removable filter component within the filter housing, the cover providing a seal for the filter module.11. The filter module as claimed in claim 10, wherein the filter module is associated with releasing means specially adapted to cooperate with the cover, the releasing means configured to secure the cover to the filter housing when operated in a first manner and to release the cover from the filter housing when operated in a second manner.12. The filter module as claimed in claim 10 or 11, wherein the removable filter component and the filter housing are configured to have a press fit relationship, and wherein the filter housing and the cover are configured to couple by relative rotation between the cover and the filter housing.13. The filter module as claimed in any of claims 10 to 12, wherein, in use, the filter housing defines the inlet on a first side, the filter housing defines the outlet on a second side opposite the first side, and wherein the removable filter component is received through a top surface of the filter housing and the cover is received by the top surface of the filter housing.14. The filter module as claimed in any preceding claim, wherein the magnetic filter medium comprises one or more magnets.15. The filter module as claimed in any preceding claim, wherein the non-magnetic filter medium comprises a mesh.16. The filter module as claimed in any preceding claim, wherein the filter module is associated with a monitoring system for monitoring flow rate in the central heating system, wherein the monitoring system comprises a sensor for measuring the flow rate, and an indicator for indicating when the flow rate has fallen to or below a predetermined value.