GB2482490A

GB2482490A - Portable Flushing Unit particularly for use with central heating systems

Info

Publication number: GB2482490A
Application number: GB1013011.0A
Authority: GB
Inventors: Balvinder Singh Nagi
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-08-03
Filing date: 2010-08-03
Publication date: 2012-02-08
Also published as: GB201013011D0

Abstract

The unit 19 comprises a liquid storage tank 20 having a lid 21, an inlet 30 for returning liquid to the tank, a pump 24 for pumping liquid from the tank to an outlet 29, and an electric motor 22 for driving the pump. The lid is secured to the tank by a quick release mechanism which may be released without the use of tools. When the lid is removed, an opening in the tank is revealed, the opening having a cross sectional area greater than 70% of the maximum internal cross sectional area of the tank in a horizontal plane. The unit may include a filter 34 in the tank through which liquid received through the inlet passes before returning to the tank and a valve 31 for diverting liquid received in the inlet to a dump 32. The lid may screw onto the tank by engaging a thread 25 on the tank, or be secured to the tank by a number of catches. The pump may be disposed in towards the bottom of the tank and attached to the lid. A connector for flushing a heat exchanger and a four way valve are also claimed.

Description

A Portable Flushin2 Unit The present invention relates to a portable flushing unit for a central heating system.

A central heating system in the context of the present specification meaning any system in which a liquid is heated by a boiler at a first location and dissipated to a secondary medium such as air or water at a remote location, for example at a radiator or the primary coil of the hot water cylinder.

An example of a known portable flushing unit is the SupaFlush 2 TM, by AquamaxTM, the essential features of which are depicted in Figure 1 of the attached drawings.

The prior art flushing unit of Figure 1 comprises a generally cylindrical tank 2 with a top portion 4 secured to the tank 2 by a number of bolts 5. Water or a cleaning agent may be inserted into the tank 5 by filler neck 6.

The flushing unit 1 has an electric motor 7 mounted to the top portion 4, the motor 7 driving a shaft 8 which in turn drives the pump 9 located in the bottom of the tank 2. The water (or cleaning agent) is pumped along pipe 10 to a four-way valve 11 where it is directed to pipe 12, through a respective three-way valve 13 to an outlet/inlet 14. A corresponding pipe 12' and three-way valve 13' (not shown) are connected to the other outlet of the four-way valve 11, so that the flow from the four way valve 11 may alternatively be directed to a second inlet/outlet 16 through the second three-way valve 13'.

In use, the outlet/inlet 14 is connected to the flow pipe of a central heating system and the inlet/outlet 16 is connected to the return pipe of a central heating system. The connection to the central heating system may be made by removing a pump motor and impeller of a pump from the central heating system and inserting an appropriate manifold into the housing of the pump, or alternatively the connections may be made to a purpose built valve anangement, as disclosed in UK Patent Application GB 2 450 501 A, installed in the system.

During flushing, the return pipe connected to the inlet/outlet 16 will receive liquid from the central heating system and this can be diverted by the three-way valve to what is termed a dump' 17, which is connected by a hose to a suitable drain. Alternatively the three-way valve may be set to direct return liquid back to the four-way 4 where it is returned via return line 18 into the tank so that it can be re-circulated.

In most central heating systems, it is desirable to reverse flush the central heating system to remove iron oxide and other deposits which tend to collect in radiators, for example. With the flushing unit of Figure 1, this can be achieved by altering the position of the two three-way valves and the four-way valve so that the outlet/inlet 14 becomes the inlet and inlet/outlet 16 becomes the outlet.

Therefore, there is no definitive inlet or outlet and to operate the system each of the two three-way valves has to be set at the correct dump', closed' or re-circulate' position and the four-way valve correspondingly has to be set to the correct one or two positions.

This can result in confusion when operating a unit especially if the operator is not familiar with the unit.

When servicing a central heating system it is also often desirable to flush the heat exchanger of the boiler especially in a combination boiler. These heat exchangers are relatively small, necessitated by the need to provide "instantaneous" hot water on demand and are often relatively easy to remove for servicing. They convey liquid from the primary circuit through ducts passing through the secondary circuit, which may for example be a hot water supply. These heat exchangers typically have a very fine structure of passages there through and may have dimension of the order 20 cm by 10 cm with a thickness of 3 cm, with one or more inlets and one more outlets.

To flush such units, the inlet and outlet of the heat exchanger are connected by pipes to the outlet/inlet 14 and inlet/outlet 16 and it is possible to flush the heat exchanger in both directions by reversing the inlet and outlets of the flushing unit 1 as previously described.

A problem with flushing heat exchangers is that it requires pipes from outlet/inlet 14 and inlet/outlet 16 of the flushing unit 1 to be connected to the respective outlet and inlet of the heat exchanger. This coupling to the heat exchanger can be difficult because the inlet and outlet of the heat exchanger are normally specific to a specific boiler. They do not normally have standard fitting and they are not normally threaded, so that some sort of clamping means is required to clamp the outlet and inlet of the heat exchanger to the pipes to the flushing unit. This is typically achieved by having an adaptor for a specific heat exchanger, or an adaptor which may be common to selected heat exchangers which have common inlet and outlet locations and inlet and outlet fitting types. The adaptor then has standard hose connections on one side and appropriate couplings on the other side for the intended heat exchanger. It may be secured to the heat exchanger, for example, by being screwed to one or more studs extending from the heat exchanger, which studs are used to mount the heat exchanger to the boiler and couple the heat exchanger to the boiler. This can be particularly problematic for it requires a plumber to know the type of heat exchanger he will encounter and to obtain the correct adaptor for that heat exchanger.

With the flushing unit of Figure 1, where the water returning to the flushing unit us to be re-circulated, which is typically necessary because the volume of the central heating system will be far in excess of the volume of the tank 2, it is sometimes desirable to filter magnetic particles from the return flow by mounting a magnetic filter, for example the SupaMeg TM compact filter, on the outlet/inlet 14 or inlet/outlet 16 of the unit.

From the above, it will be appreciated that correctly flushing a central heating system, particularly one which includes a combination boiler, can be quite an involved process, particularly if the return is to be filtered.

It is an object of the present invention to provide an improved flushing unit for a central heating system.

According to the first aspect of the present invention there is provided a portable flushing unit for a central heating system, the unit comprising: a liquid storage tank; a lid for the tank; a liquid outlet for discharging liquid from the tank; a liquid inlet for returning liquid to the tank; a pump for pumping liquid from the tank to the outlet; and an electric motor for the pump, characterised in that the lid of the tank engages with the tank by means of a quick release mechanism which can be released without any tools and wherein the opening in the top of the tank, with the lid removed, is greater than 70% of the maximum internal cross sectional area of the tank in a horizontal plane.

For the purposes of this specification, a portable flushing unit' is defined as one which is to be carried by hand by a user to an appropriate location. A quick release mechanism' is defined as a mechanism which is so simple in its nature so as to make it practicable for a user to remove and replace the lid a number of times during a typical flushing procedure and would include a unit having a lid which can be screwed on, by rotating the lid relative to the tank, or which is secured and released by clips without the requirement for any tools to be used, or a number of screw clamps, for example. The definition would exclude any securing means which required tools to release it, or any fixing which would take such a time to secure and release, that it would be impractical to successively release and secure the lid during the flushing operation.

The provision of a lid secured to the tank by a quick release mechanism, which when removed exposes an opening to the tank which is greater than 70% of the maximum internal cross-sectional area of the tank in a horizontal plane, makes the space within the tank easily accessible to the user which space can then be utilised to provide a number of features which are particularly advantageous over those of prior art flushing units.

It is particularly advantageous if the opening in the top of the tank is greater than 95% of the maximum cross-sectional area of the tank in a horizontal plane, or equal to the maximum internal cross-sectional area of the tank in a horizontal plane, for then completely unrestricted access to the tank is provided and also the area of the lid which can be used to make connections to the tank is increased.

One particularly advantageous arrangement employs a cylindrical tank, wherein the lid screws onto the tank engaging with a thread on the outer surface of the tank. Not only does this provide a convenient quick release mechanism, enabling the lid to be removed by rotating it one or more turns, or part of a turn relative to the tank, but it can also provide a uniform contact pressure around a rim of the tank where it contacts with the lid. Also, if the lid is of a thicker material than the tank, particularly the outer rim of the lid, this will act to strengthen the tank permitting the walls of the tank to be thinner, reducing the weight of the tank.

Preferably, the unit comprises a filter located in the tank through which liquid received through the inlet passes before being returned to the tank. The provision of easy access to the tank, achieved by the present invention, makes it possible to locate the filter in the tank and for it to be practicable, during a flushing operation, to pause the flushing operation, possibly prior to reverse flushing, to remove and flush the filter. Furthermore, the filter can be permanently fitted, possibly to the bottom surface of the lid of the tank avoiding the need to connect the filter externally of the flushing unit prior to use and to avoid the possibility of the filter being damaged during transit of the portable flushing unit.

It can also ensures that all liquid returning to the tank is filtered, ensuring that particulate material cannot be inadvertently returned to the tank, which may cause damage to the pump. Also, the flow path through the filter is in the same direction whether the central heating system is being forward or reverse flushed, making it possible to use a filter screen in the filter, without the need to change any connections to the filter prior to changing the direction of flushing of the central heating system. The filter may be a screen filter, a magnetic filter or a combined filter. Any leakage from the filter will be returned directly to the tank.

If the filter is a screen filter, or if it includes a magnetic filter but additional magnetic filtering is required, the provision of easy access to the tank makes it possible to place a magnet in the bottom of the tank, preferably with a string attached for easy removal, which magnet will collect any magnetic particles from the tank. The magnet may be in a bag or similar container from which it may be removed, in order to easily remove the magnetic particles from the magnet simply by removing the magnet from the container.

Preferably, the pump is located towards the bottom of the tank and is attached to the lid and driven by a shaft connected to the motor fixed to the top of the lid. This arrangement enables the motor and pump to be removed from the tank together with any associated pipe work simply by removing the lid from the tank making it easy to rinse the tank or to store items in the tank during transit. Alternatively the motor could be comprised in the main body of the pump in what is termed a submersible pump.

The unit preferably comprises two hoses for connecting the inlet and outlet of the unit to a central heating system, wherein the unit is ananged such that when the lid is mounted upon the tank an unobstructed free space is left in the bottom of the tank extending 7cm from the bottom of the tank, in which space the hoses can be stored. Thus the lid can be quickly removed from the tank after a completion of a job and the hoses, possibly together with an electrical supply cable and other ancillary equipment, stored in the tank with the lid attached to the tank so the tank and associated items can be transported as a single unit.

Advantageously, the pump conveys liquid to the outlet of the unit by a pipe and the unit further comprises a valve for diverting liquid from the pump to a second outlet located in the tank. The provision of a second outlet located in the tank, together with ready access being obtainable to the tank, makes it possible to connect a heat exchanger to the outlet in the tank of a the flushing unit and to operate the flushing unit so as to flush the heat exchanger, with liquid from the heat exchanger being returned directly to the tank without the need to provide any connection between the outlet of the heat exchanger and the tank.

A particular advantage of this is that only a single connection needs to be made to the heat exchanger and this does not need to be leak proof for any liquids leaking from the connection will be returned to the tank. Therefore, it may be possible to use a universal connector which can connect to both inlets and outlets to most, or at least a considerable number of heat exchanger types, avoiding the need to obtain specific adaptors for a specific heat exchanger.

According to a second aspect of the present invention, there is provided a connector for flushing a heat exchanger comprising: an adaptor having a first end arranged to be connected to a pipe, a second end comprising a nozzle for non-interlocking insertion in an inlet or outlet of a heat exchanger, a flange between the first and second ends; and a G-clamp having a first contact point for engaging with the adaptor and a second contact point opposed to the first contact point for engaging with a surface of a heat exchanger opposite an inlet or outlet of a heat exchanger, wherein the clamp can be operated to decrease the distance between the first and second contact points to clamp the adaptor in an inlet or outlet of a heat exchanger, with the nozzle protruding into the inlet or outlet and the flange sealing, to some extent, with the inlet or outlet of the heat exchanger. By non-interlocking it is meant that the nozzle is not retained in the inlet or outlet by the adaptor engaging with the inlet or outlet of the heat exchanger.

A connector in accordance with the second aspect of the invention may connect to a considerable number of different types of inlets and outlets of heat exchangers and it may be designed to connect to almost all heat exchangers.

It is particularly advantageous if the nozzle of the adaptor has radially extending apertures, for this enables the adaptor when inserted in the inlet or outlet of a heat exchanger to direct liquid perpendicular to the axis of the connector, which will normally be in the direction of the passages conveying liquid through the heat exchanger.

A connector in accordance with a second aspect of the present invention can advantageously be employed with a flushing unit in accordance with the first aspect of the present invention, wherein the pump of the flushing unit conveys liquid to the outlet of the flushing unit by a pipe and the unit further comprises a valve for diverting liquid from the pump of the flushing unit to a second outlet located within the tank of the flushing unit, for this enables the connector to be connected to that second outlet within the tank so that a heat exchanger may be flushed within the tank itself, so that the outlet of the heat exchanger can return directly to the tank and the adaptor need not be a leak proof fit with the inlet of the heat exchanger.

According to a third aspect of the present invention, there is provided a four-way valve comprising a first component having a first port and a second port of the valve and a second component having a third port and a fourth port of the valve, wherein the first component has a first planar surface which the first and second ports extend to and the second component has a second planar surface to which the third and fourth ports extend to, the first and second planar surfaces abutting together with the first and second components being rotatable relative to each other about an axis orthogonal to and passing through the two planar surfaces, the components being ananged such that: in a first rotational position the first port is aligned with the third port so that liquid can flow substantially unimpeded from the first port to the third port and the second port is aligned with the fourth port so that liquid can flow substantially unimpeded from the second port to the fourth port; and in a second rotational position the first port is aligned with the fourth port so that liquid can flow substantially unimpeded from the first port to the fourth port and the second port is aligned with the third port so that liquid can flow substantially unimpeded from the second port to the third port.

A four-way valve in accordance with the third aspect of the present invention is particularly advantageous, for if first and second ports are connected to the inlet and outlet of a flushing device and the third and fourth outlet ports are connected to the flow and return pipes of a central heating system, then flushing can be reversed in the central heating system simply by rotating the first component of the four-way valve 180° relative to the second component of the valve.

It is particularly advantageous if the four ports each comprise apertures passing straight through respective ones of the first or second components and wherein, in the first rotational position, the first and third ports and second and fourth ports provide respective linear passages, each passing completely through the valve and, in the second rotational position, the first and third ports and second fourth ports provide respective linear passages each passing completely through the valve.

By employing this arrangement of four way valve, if the user knows which of the first and second ports is the inlet and outlet he can immediately identify which of the third ports will be the inlet and outlet for they will be directly aligned with appropriate ones of the first and second ports.

It is particularly advantageous if the four-way valve in accordance with the third aspect of the present invention is employed with a flushing unit in accordance with a first aspect of the present invention, wherein the pump of the flushing unit is connected to the first port of the four-way valve and the second port of the four-way valve is connected to a return to the tank, wherein in the first rotational position the third port of the four-way valve is the outlet of the unit and the fourth port is the inlet of the unit and in the second rotational position the fourth port of the four-way valve is an outlet of the unit and the third port of the four-way valve is the inlet of the unit.

The above arrangement permits the flushing unit to have a dedicated outlet and a dedicate inlet (or return) considerably simplifying operation of the flushing unit and likewise reducing the possibility of incorrect operation. The four-way valve then permits the flow in the central heating system to be reversed simply by rotating the first component of the valve through 180° relative to the second component, reducing the possibility of erroneous operation. This is particularly the case wherein the four ports of the four-way valve each comprise apertures passing straight through respective ones of the first or second components and wherein, in the first rotational position, the first and third ports and second and fourth ports provide respective linear passages, each passing completely through the valve and, in the second rotational position, the first and third ports and second fourth ports provide respective linear passages each passing completely through the valve.

The flushing unit and valve used in the above manner provide a visible connection between the dedicated outlet or inlet of the flushing device and flow or return pipe of the central heating system.

Embodiments, encompassing all aspect of the present invention, will now be described by way of example only, with reference to the accompanying figures, of which:

Figure 1 discloses a prior art flushing unit;

Figure 2 is a schematic diagram of a flushing unit in accordance with a first aspect of the present invention; Figure 3a is an end elevation of a four-way valve in accordance with a third aspect of the present invention; Figure 3b is a longitudinal cross-section of the valve of Figure 3a; Figure 3c is the opposite end elevation to that of Figure 3a; Figure 4 illustrates a connector in accordance with a second aspect of the present invention; and Figure 5 shows the connector of Figure 4 connected to an inlet of a heat exchanger.

Refening to Figure 1, a description of this prior art flushing unit is given in the

introductory portion of the present specification.

Refening now to Figure 2, a flushing unit in accordance with the present invention is indicated generally as 19 and comprises a liquid storage tank 20, a lid 21, an electric motor 22 mounted to the lid 21 and a motor shaft 23 extending from the electric motor 22 to a pump 24 within the tank 20.

In the specific embodiment shown, the tank 20 is cylindrical and is threaded at an upper edge of the external wall which thread 25 engages with a corresponding thread on the lid 21, enabling the lid 21 to be quickly released without tools from the tank 20, by rotating it relative to the tank 20.

S

With the lid 21 attached to the tank 20, pump 24 is suspended a distance d of at least 7 cm from the bottom of the tank to define a storage space X. The pump 24 draws liquid from within the tank 20 and forces it along pipe 26 to a three-way valve 27 located within the tank 20. When the valve is in a first position, liquid from the pump 24 is fed along pipe 28 to an outlet 29 of the flushing unit 19.

The flushing unit 19 additionally comprises an inlet 30 connected to a three-way inlet valve 31. The inlet valve 31 directs liquid either to an additional outlet 32, termed a dump' which is intended to be connected to an external drain, or directs the liquid along pipe 33 and into a filter 34. The filter 34 is located within the tank 20 and has an outlet 35 which discharges directly into the tank 20. The inlet valve 31 and filter 34 are mounted to the lid 21 and are removed with the lid. When the lid is removed the filter 34 can be unscrewed from its mounting and emptied. The filter may be of any conventional type comprising a filter screen and/or magnetic filter to collect magnetic particles such as iron oxide.

Three-way outlet valve 27, in addition to being connected to the outlet 29 is connected by pipe 36 to a coupling 37 within the tank 20, so that in use liquid from the pump 24 may be directed by the outlet valve 27 to either the coupling 37 or the outlet 29 of the flushing unit 29.

All the components of the flushing unit, so far described, are mounted to the lid of the flushing unit 19 such that when the lid 21 of the flushing unit 19 is removed from the tank 20, all the components are removed from the tank without the necessity to disconnect any one of the various components.

In the specific embodiment illustrated, the lid 21 is shown as being screwed to the top of the tank, however in alternative arrangements it could be attached by a number of catches operating between a lid 21 and the tank 20. Also, the lid 21 will typically have a handle attached to it, which has been omitted for reasons of clarity, which handle, when the lid 21 is mounted on the tank 20, will enable the complete flushing unit 19 to be easily canied. Furthermore, when being canied or transported any hoses or additional equipment associated with the flushing unit may be stored in the space X' below and around the pump 24.

In use, the outlet 29 may be connected to the inlet of a central heating system and the inlet 30 connected to the outlet of the central heating system, with the outlet valve 27 directing fluid from the pump 24 to the outlet 29. Operation of the pump will then force liquid from within the tank 20, which may be water or a cleaner, typically in an acid cleaner, back to the inlet 30. The return liquid at the inlet 30 can be directed by the inlet valve 31, either to return to the tank 20 via filter 34, or to be directed to the dump 32 where it will be released to an external drain. Because a central heating system will typically have a larger capacity than the tank 20, fluid will be re-circulated through the tank to ensure the cleaning agent passes throughout the whole system prior to the system being drained or released through the dump 32.

The flushing unit described with reference to Figure 2 is relatively simply in its operation, having a dedicated outlet 29 and a dedicated inlet 30, limiting the possibility for confusion when connecting to a central heating system. However, without disconnecting and switching the hoses between the inlet and the outlet it is not possible to both flush and reverse flush a central heating system, a technique it is often desired to perform. This can be addressed by attaching a four-way reversing valve, as shown in Figures 3a to 3c, to the outlet 29 and inlet 30 of the flushing unit.

Referring now to Figures 3a to 3c there is illustrated a four-way reversing valve, indicated generally as 38, comprising a first component 39 and a second component 40.

The first component 39 comprises a cylindrical block having a cylindrical recess 41 at one end and a first port 42 and a second port 43 at the other end. The ports 42 and 43 have associated passages 44 and 45 extending through the first component 39 to the cylindrical recess 41.

The second component 40 of the reversing valve 38 has a third port 46 and a fifth 47 of the reversing valve 38, each port having a respective passageway 48, 49 extending between the port and an inner face of the second component 40.

The second component 40 is cylindrical and fits within the cylindrical recess 41 of the first component 39, so that the first component may be rotated relative to the second component about a longitudinal access of the reversing valve 38. The first and second components 39 and 40 of the reversing valve 38 are drilled through their central longitudinal axis, with a bolt 50 passing therethrough to engage with a nut 51 to clamp the first component 39 to the second component 40, but to permit the first component 39 to rotate relative to the second component 40.

Each pair of passages 44, 45 are located at opposite sides of the longitudinal axis of the respective component 39 or 40 and all four passageways 44, 45, 48 and 49 are equidistant from the central axis such that the passageways may be aligned in a first position, as shown in Figure 3b. Here, the first port 42 is connected to the third port 46 and the second port 43 is connected to the fourth port 44, or the first component 39 may be rotated through 180° relative to the second component 40 whereby the second port 43 will be connected to the third port 46 and the first port 42 will be connected to the fourth port 47. 0-ring seals 50 and 51 are embedded in annular apertures in the internal face of cylindrical recess 41 of the first component 39 at locations centred on passages 44 and 45 respectively. These act to ensure a liquid tight seal between the passages when they are aligned.

The reversing valve of Figures 3a to 3c, in use, will have a first port 42 connected to the outlet of a flushing machine, the second port 43 connected to the inlet of the flushing machine, a fourth port 46 connected to the inlet of a central heating system and a fourth port 47 connected to the outlet of a central heating system. Thus, when orientated as shown in Figure 3b, the flushing unit will cause the central heating system to be flushed in a first direction. The central heating system can then be flushed in a reverse direction simply by rotating the first component 39 of the reversing valve 38 through 180° relative to the second component. Straight passageways 44, 48 and 45, 49 through the reversing valve 38 ensure that the flow path through the valve is self-evident and thus the flow paths between the flushing unit and the central heating system can be traced by eye.

The reversing valve 38 of Figures 3a to Figure 3c can be fitted to the inlet 30 and outlet 29 of the flushing unit 19 of Figure 2, providing a quick and easy way of reversing the flow through a central heating system whilst maintaining the advantages of having a dedicated outlet on the flushing system. The straight passageways in the reversing valve 38 enabling the outlet port of the flushing valve to be immediately identified for this will be the one that is connected straight-through the reversing valve 38 to the outlet port 29 of the flushing unit 19.

Whilst flushing a central heating system, or in addition to flushing a central heating system, the flushing unit 19 of Figure 2 may be required to flush the heat exchanger of a boiler, as for example the heat exchanger of a combination boiler. Such heat exchangers are typically of the order of 20 cm by 10 cm by 5 cm thick, with non-standard outlets and inlets. Figure 4 illustrates a connector, indicated generally as 52 suitable for connecting to various types of heat exchanger. This comprises a G-clamp 53 and an adaptor 54. Tn the embodiment illustrated, the adaptor 54 has a threaded fitting 55 at one end for connecting to the coupling 37 of the flushing unit 19 of Figure 2. However, the threaded fitting 55 may be replaced by any fitting enabling it to be coupled to an appropriate fluid source and the connector 52 has application other than directly to the flushing unit of Figure 2.

At the opposite end of the connector 52 is a nozzle 56 spaced from threaded fitting by a flange 57 and a waist portion 58 which engages with the G-clamp 53. The adaptor 54 has a central passageway 59 and a plurality of radial passageways connected to the central passageway 59. The nozzle 56 is of a relatively smaller diameter so that it may be inserted into most outlets and inlets of standard heat exchangers. The flange 57 is relatively large and the diameter may be more than 2.5cm, enabling it to cover the aperture of the inlet or outlet of most heat exchangers.

Figure 5 illustrates the connector 52 mounted on a heat exchanger 61, such that the adaptor 54 is connected to inlet port 61 of the heat exchanger with the flange 57 sealing the inlet port 62 by the pressure exerted by the G-clamp 53. In this position, the nozzle extends into the heat exchanger 59, so that fluid forced through the adaptor 54 into the heat exchanger 61 exists central passageway 59 and the radial passageways 60 such that the spaces between adjacent plates of the heat exchanger are flushed with the flushing liquid exiting the heat exchange via the outlet 63.

When the connector 52 is fitted to the coupling 37 of the flushing unit 19 of Figure 2 and the outlet valve 27 is set so that fluid from the pump 24 is forced through the coupling 37, adaptor 54 and heat exchanger 51 of Figure 5, the liquid may exit the outlet 63 of the heat exchanger directly into the tank because the heat exchanger is located in the tank. This avoids the need to make an additional coupling to the outlet 63 of the heat exchanger 61. The easy access to the inside of the tank 20 of the flushing unit 19 of Figure 2, makes it possible to readily flush the heat exchanger 61 of Figure 5 within the tank 20.

Although the connector 52 of Figure 5 finds particular application with the flushing unit of Figure 2, it may also be used with standard flushing units with possibly two such connectors being used in pairs to connect to both the inlet and the outlet of a heat exchanger to be flushed.

One embodiment of each aspect of the present invention has been described above by way of example only, but it will be realised that many alternative embodiments are possible within the scope of the appended claims.

Claims

Claims 1. A portable flushing unit for a central heating system, the unit comprising: a liquid storage tank; a lid for the tank; a liquid outlet for discharging liquid from the tank; a liquid inlet for returning liquid to the tank; a pump for pumping liquid from the tank to the outlet; and an electric motor for driving the pump, characterised in that the lid of the tank engages with the tank by means of a quick release mechanism, which can be released without any tools and wherein the opening in the top of the tank, with the lid removed, is greater than 70% of the maximum internal cross sectional area of the tank in a horizontal plane.
2. A unit as claimed in Claim 1, wherein the opening in the top of the tank is greater than 95% of the maximum internal cross sectional area of the tank in a horizontal plane.
3. A unit as claimed in Claim 1 or 2, wherein the opening in the top of the tank is equal to the maximum internal cross sectional area of the tank in a horizontal plane.
4. A unit as claimed in Claim 1, 2 or 3, wherein the tank is cylindrical and the lid screws on to the tank, engaging with a thread on the outer surface of the tank.
5. A unit as claimed in any preceding claim, further comprising a filter located in the tank through which liquid received through the inlet passes before being returned to the tank.
6. A unit as claimed in any preceding claim, wherein the pump is located towards the bottom of the tank and is attached to the lid and driven by a shaft connected to the motor fixed to the top of the lid.
7. A unit as claimed in any preceding claim, further comprising two hoses for connecting the inlet and outlet to a central heating system wherein, when the lid is on the tank, an unobstructed free space is left in the bottom of the tank extending 7 cm from the bottom of the tank in which the hoses can be stored.
8. A unit as claimed in any preceding claim, wherein the inlet comprises a valve for diverting liquid received in the inlet to a dump to be discharged from the unit without passing through the tank.
9. A unit as claimed in any preceding claim, wherein the pump conveys liquid to the outlet by a pipe, the unit further comprising a valve for diverting liquid from the pump to a second outlet located within the tank.
10. A connector for flushing a heat exchanger comprising: an adaptor having an first end ananged to be connected to a pipe, a second end comprising a nozzle for non-interlocking insertion in an inlet or outlet of a heat exchanger, a flange between the first and second ends; and a G-clamp having a first contact point for engaging with the adaptor and a second contact point opposed to the first contact point for engaging with a surface of a heat exchanger opposite an inlet or outlet of the heat exchanger, wherein the clamp can be operated to decrease the distance between the first and second contact points to clamp the adaptor in the inlet or outlet of the heat exchanger, with the nozzle protruding into the inlet or outlet and the flange sealing, to some extent, with the inlet or outlet of the heat exchanger.
11. A connector as claimed in Claim 10, wherein the nozzle of the adaptor has radially extending apertures.
12. A flushing unit as claimed in Claim 9, comprising a connector as claimed in Claim 10 or 11, wherein the first end of the adaptor is connected to the second outlet in the tank of the flushing unit.
13. A four-way valve comprising a first component having a first port and a second port of the valve and a second component having a third port and a fourth port of the valve, wherein the first component has a first planar surface which the first and second ports extend to and the second component has a second planar surface to which the third and fourth ports extend to, the first and second planar surfaces abutting together with the first and second components being rotatable relative to each other about an axis orthogonal to and passing through the two planar surfaces, the components being arranged such that: in a first rotational position the first port is aligned with the third port so that liquid can flow substantially unimpeded from the first port to the third port and the second port is aligned with the fourth port so that liquid can flow substantially unimpeded from the second port to the fourth port; and in a second rotational position the first port is aligned with the fourth port so that liquid can flow substantially unimpeded from the first port to the fourth port and the second port is aligned with the third port so that liquid can flow substantially unimpeded from the second port to the third port.
14. A valve as claimed in Claim 13, wherein the four ports each comprise passages passing straight through respective ones of the first or second components and wherein, in the first rotational position, the first and third ports and second and fourth ports provide respective linear passages, each passing completely through the valve and, in the second rotational position, the first and third ports and second fourth ports provide respective linear passages each passing completely through the valve.
15. A unit as claimed in any one of Claims 1 to 9 or 12, comprising a valve as claimed in Claim 13 or 14, wherein the pump is connected to the first port of the four-way valve and the second port of the four-way valve is connected to a return to the tank, wherein in the first rotational position the third port of the four-way valve is the outlet of the unit and the fourth port is the inlet of the unit and in the second rotational position the fourth port of the four-way valve is an outlet of the unit and the third port of the four-way valve is the inlet of the unit.
16. A portable flushing unit substantially as hereinbefore described, with reference to and/or as illustrated in one or more of the accompanying figures.
17. A four-way valve substantially as hereinbefore described, with reference to and/or as illustrated in one or more of the accompanying figures.
18. A connector for flushing a heat exchanger substantially as hereinbefore described, with reference to and/or as illustrated in one or more of the accompanying figures.