GB2099984A - Solar energy collector heat exchanger - Google Patents

Abstract

A heat exchanger, which may act as a solar heater for a swimming pool, comprises a plurality of flexible pipes 4 connected in parallel between an inlet manifold 1 and an outlet manifold 2. The pipes 4 together thus constitute a solar connector or panel which, because of its flexibility does not require a carefully prepared support. The heater is designed to be connected in series with the pool circulating system and because the desired temperature rise is small, elaborate and expensive insulating and glazing arrangements are not required. The heat exchanger may alternatively be used for heat exchange between fluids. <IMAGE>

Description

SPECIFICATION Solar energy collector This invention relates to a solar energy collector which is particularly, aithough not exclusively, of use for heating swimming pools.

Solar energy collectors are known which are in the form of so-called "solar panels" which generally comprise a metal collector plate arranged to receive solar radiation, and metal tubing soldered or brazed to the collecting plate and through which a transfer medium, such as water is circulated, the collector plate and the metal tubing secured thereto being accommodated within an insulated casing which includes a glass cover intended to allow the passage of solar radiation but to inhibit loss of heat from within the casing.

Such solar panels have various disadvantages.

Thus, they are somewhat fragile and require a rigid, fairly accurately formed support. Furthermore, while they are efficient as long as the glass covers and collector plates face substantially perpendicularly to the direction of incidence of solar radiation, their efficiency falls off rapidly at smaller angles of incidence due, infer alia, to reflection from the surfaces of the glass plate. Known solar panels also have the disadvantage that, because of the vulnerability of the glass panes, they must be placed in locations where accidental damage is relatively unlikely for example, elevated above ground level or, if accommodated at ground level, the area of ground occupied thereby must be set aside exclu sively for that purpose.Furthermore, known solar panels of this kind have an extremely high initial cost and require skilled labourto install. It is among the objects of the present invention to provide a solar energy collector in which the above noted disadvantages may be avoided and which is particularly suitable for applications in which the required temperature rise of the thermal mass to be heated with respect to the surroundings is relatively small, for example for applications such as heating swimming pools.

According to the invention there is provided a solar energy collector comprising an inlet manifold, an outlet manifold and a plurality of flexible pipes connected in parallel between said inlet and outlet manifolds, at least the major part of the solar energy-collecting surface of the collector being constituted by the surfaces of said flexible pipes.

In the preferred embodiment of the invention, in which the required temperature rise is relatively low, no transparent layer is required above the flexible pipes for heat insulation purposes, and this, coupled with the flexibility of the tubes extending between the manifolds allows these tubes simply two be laid upon the surface of the ground or some other convenient surface and to be treated as a kind of flexible paving, so that the area of ground over which the collector is extended may also serve some other purpose, for example as part of a drive, a games area, part of a pool surround, etc.As the solar energy collecting pipes are flexible they are not damaged by being temporarily restricted by, for example, being trodden on, while because there are a plurality of such flexible pipes connected in parallel between the manifolds, localised constriction of one or more of the pipes has a negligible effect upon the effective total flow capacity.

Embodiments of the invention are described below with reference to the accompanying drawings in which: Figure 1 is a schematic plan view of a solar energy collector embodying the invention, Figure 2 is a plan view of a part of the solar energy collector of Figure 1, Figure 3 is a schematic view in vertical section of the solar energy collector, Figure 4 is a schematic view of a flow control system for the collector, Figure 5 is a schematic vertical section view illustrating the mounting of the collector on the wall of a swimming pool, Figure 6 is a schematic vertical section view illustrating the mounting of the collector as a flat surround at the edge of a swimming pool, Figure 7 is a schematic perspective view showing a collector embodying the invention supported by a supporting frame, Figure 8 is a schematic plan view showing one way in which adjoining, parallel, flexible pipes of the system may be held together, Figure 9 is a schematic plan view showing another way in which adjoining, parallel, flexible pipes of the system may be held together, Figure 10 is a cross-sectional view corresponding to Figures, and Figure 1 is a longitudinal section view of an alternative form of joint between manifold pipe sections.

Referring to Figure 1, the solar energy collector comprises an inlet manifold 1, an outlet manifold 2, and a plurality of flexible pipes 4, connected in parallel with one another between the manifolds 1 and 2. As shown in Figure 2, each of the manifolds 1, 2 comprises one or more identical sections of semi-rigid plastics tubing, for example polyethylene, having extending radially therefrom a plurality of spigots 6, the spigots 6 in each section 5 being disposed at regular intervals in the longitudinal direction of the pipe section 5 and being disposed in a common longitudinally extending diametral plane of the section 5, The spigots 6 are preferably of the same material as the pipe sections 5 and may be formed integrally therewith or screwed into screw threaded apertures formed in the wall of the section 5 and fixed sealingly with respect to the section 5 by means of a suitable adhesive sealant.

Each of the flexible pipes 4 is fitted at one end over a respective spigot 6 of one pipe section 5 of the inlet manifold and is fitted at its opposite end over a corresponding spigot 6 of the opposite pipe section 5 of the outlet manifold. Thus, each pipe section 5 of the inlet manifold forms, together with an opposite pipe section 5 of the outlet manifold and the group of flexible pipes extending between the two sections in question, a respective module of the collector.It will be appreciated that the arrangement is preferably such that no flexible pipe 4 crosses over any other flexible pipe 4 at any point, so that the module may be stretched out on a flat surface as indicated in Figures 1 and 3 in such a way that the pipes 4 extend in a grid, parallel with one another and spaced slightly apart from one another in the longitudinal direction of the manifolds 1 and 2. The pipes 4 may, as illustrated in Figure 1, be all of the same length so that the module, when stretched out flat in the manner indicated, is substantially rectangular with the pipes 4 extending perpendicularly to the manifolds 1 and 2. However, as will appear from what follows, the precise configuration adopted is variable, depending on the specific location etc. in which the collector is to be located.

The flexible pipes 4 are conveniently of inexpensive black plastics garden hose, formed with longitudinally extending parallel ribs on its outer periphery.

Each length of pipe 4 may simply be sealed with respect to the spigots over which it is fitted by virtue of the tension and clinging tendency of the plastics material itself, or may additionally be clamped by means of a suitable clip (not shown) and/or using a suitable sealant adhesive.

Each pipe section 5 has, at each end thereof, a length which is free from spigots 6, and adjoining pipe sections 5 in the same manifold are connected by connecting sleeves 12 fitted over the free end parts of the adjoining pipe sections 5. Each manifold 1,2 is connected at one end, via flexible connection pipes 8, to an application system (for example a swimming pool circulation system), possibly through the intermediary of a control system. The material preferred for the pipes 8 is plastics piping of the kind comprising a helically extending corrugation within which is incorporated a heiical reinforcing element, so that the pipe has good resistance to lateral crusing yet is flexible enough to bend readily transversely.The pipes 8 are connected with the manifolds 1, 2 by connector arrangements fitted over the respective end portions of the respective pipe sections adjoining the pipes 8, while the ends of the manifolds 1, 2, remote from the application system and connection pipes 8 are closed by plastics end caps 14 fitted over the free ends of the respective pipe sections.

Depending upon the features of the specific installation concerned, adjoining pipe sections 5 in a manifold 1 or 2 may be connected in end to end engagement with one another by a short plastics sleeve fitted over the adjoining end parts, the plastics sleeve being either rigid or semi-flexible and being sealed with respect to the pipe sections 5 either by virtue of the natural clinging properties of the plastics material or by a suitable sealant/adhesive, or clamping rings or any other arrangement. In some installations, it may be necessary or desirable to place two adjoining pipe sections 5 of a manifold at some distance from one another, and in such a case the pipe sections can be connected with one another via lengths of flexible plastics piping.

As indicated above, the preferred embodiment is particularly intended as a heater for a swimming pool. It will be understood that a typical swimming pool installation incorporates at least one, and generally two, filtration and cleaning systems, incorporating a circulation pump and a conduit system through which the pool water is circulated by means of said pump at a high volumetric rate, typically several gallons per second. The diameters of the manifolds 1, 2 are such as to cope with such a volumetric flow rate with little pressure drop, and likewise, since the pipes 4 are connected in parallel between the manifolds, the net volumetric flow resistance of these pipes 4 is small.It is therefore possible to connect the solar energy collector substantially in series with the existing pool circulation system without significantly impeding the operation of the latter, such connection being effected through the connection pipes 8.

However, in order to afford a measure of control, and to allow the solar energy collector to be isolated from the pool circulation system without impeding the operation of the latter, it is preferable to utilise a control system incorporating appropriate valves.

Such a control system may take the very simple form shown in Figure 4 in which a first valve 14 is connected in a conduit 15 which is connected in series with the pool circulation circuit, and branch pipes 16 and 17 branch off from the conduit from respective Tjunctions with the conduit 15 on either side of the valve 14, the branch pipes 16 and 17 having respective valves 18 and 19 disposed therein.

The valves 14, 18 and 19 conveniently take the form of simple screw-down valves.

By closing the valve 14 fully and opening the valves 18 and 15 fully the solar energy collector will be connected fully in series with the pool circulation circuit, whereas with the valves 18 and 19 fully closed and the valve 14 open the solar energy collectorwill be isoiated from the pool circulating system. With the valves 14, 18 and 19 only partially closed, partofthewaterflowing around the pool circulation system will pass through the solar energy collector whereas a by-pass portion will pass through the valve 14 and it will be appreciated that by adjustment of the relative positions of the valves 18, 19 and 14 it is possible to vary the rate of heat extraction from the solar energy collector.

For most users, the greater part of swimming pool usage falls in the summer months, and consequently the daily period for which the pool circulation and filtration system must be operated is greatest in the summer months and is, generally, greatest in periods of sunshine, because usage is then greater, so that over the period where pool usage is likely to be greatest, the most advantageous heating effect from solar radiation is obtainable and at the same time the pool circulation which would be necessary in any case generally corresponds approximately with the daily period over which useful solar radiation can be received, so that there are virtually no additional energy losses atributableto the operation of the collector described.

Because the desired temperature difference between the pool water and the mean ambient temperature is not great by solar heating standards, and the difference between this temperature and the current ambient temperature in the daylight hours when the system will be operated is even smaller, heat losses from the plastics pipes 4 are relatively insignificant, even to the ground, so that it is unnecessary to provide any transparent insulating covering over the pipes 4, in the way of glass panelling or plastics sheeting. The collector may simply be laid upon an area of virtually unprepared ground, preferably having a southerly aspect, and the individual pipes 4, being flexible, will conform to the contour of the underlying ground to be fully supported thereby.

The lack of any shiny transparent covering panels, coupled with the effect of the longitudinal grooves or fins on the pipes 4 in rendering the pipes 4 effectively mats to the solar radiation, means that loss of incident radiation through reflection from the collector is relatively low so that it is unnecessary to "track" the collector around with the sun, as is done with some solar panel arrangements.

The solar energy collector described may readily be adapted to various situations and sites.

Thus, for example, where, as shown in the schematic sectional view of Figure 5, a swimming pool has a peripheral wall 20 of which at least a part (preferably facing in a southerly direction) on the exterior of the pool is inclined downwardly from the level of the edge 21 of the pool in a direction away from the pool, the collector may be laid on this sloping surface, with the tubes 4 extending horizontally and lying one against one another up the slope as indicated, the lowermost tube 4 being supported by the ground 22 at the foot of the sloping surface, or by a ledge or abutment provided for this purpose.

While the tubes 4 will normally stay in place readily even on fairly steep slopes if desired the tubes may be held against the sloping wall at intervals by battens or the like.

It is, of course, perfectly feasible to have each pipe 4 running from top to bottom of the sloping surface, with the manifolds 1 and 2 extending horizontally along the top and bottom of the slope, but the preferred arrangement is less troublesome and costly to set up.

The arrangement described with reference to Figure 5 may, of course, be utilised whetherthe sloping wall in question is straight or curved as viewed in plan. In the latter case, since the surface on which the pipes 4 lie will be part conical, if the manifolds 1, 2 are to extend straight down the slope, the lengths of the individual pipes 4 must increase progressively from top to bottom. This would also be true of variants in which, for example the pool is set in the ground but with an earth mound sloping downwardly, with an appropriate aspect, from the pool.

Another arrangement which may be utilised is illustrated in Figure 6. In this arrangement, the pipes 4 are laid side by side on the horizontal margin 24 of the pool, the pipes 4 running circumferentially around the pool and together affording an effective non-slip surface for bathers to walk or sit upon.

Normally even a fairly low positive water pressure within the pipes is sufficient to support the suitably spread load of a person without significant restriction of the pipes, but even if one or several of the pipes should be restricted temporarily by a localised load, the effect on the flow resistance of the collector as a whole is negligible because of the larger number of unrestricted pipes, and when the load is removed, the temporarily restricted pipes are restored to their original, open condition once more by their inherent resilience and by water pressure.

Similarly, it is possible to lay the pipes 4 side by side over a driveway to a garage or the like, as the temporary restriction of a limited number of the pipes 4 by the passage of a vehicle has no significant effect.

The collector described may also be conveniently laid on a suitably oriented roof surface, for example on a flat or inclined roof, or on a "wave" roof, (e.g. the roof of an indoor pool).

Although a significant advantage of the present solar energy collector is that it is not necessary to provide a space solely dedicated to the collector, there are, of course, situations in which this consideration is of minor relevance, and in such situations a specific supporting structure may be provided for the pipes 4. Such a structure may, for example, as shown in Figure 7, take the form of a frame 28, for example of timber, providing an inclined surface 29 on which the pipes 4 and manifolds 1, 2 rest, the frame 28 being supported at its higher end by a vertical or inclined support 30.

Such a structure may be utilised with other such structures as a fence.

As indicated above, the pipes 4 are preferably formed externally with longitudinally extending ribs and grooves regularly distributed around the circumference of the pipes. It has been found advantageous to arrange the adjacent pipes 4 in the device in direct engagement with one another, for if this is done the ribs on adjoining pipes interlock so that it is not possible to displace one pipe 4 individually from between the adjoining pipes 4, and thus considerable integrity is afforded the structure in a simple and straightforward manner.

The manifolds 1, 2 and pipes 8 may, of course, be readly concealed, for example by being installed in suitably covered channels or trenches from which the pipes 4 emerge. Such an arrangement is in any case preferable, as the manifolds 1, 2 and pipes 8, besides being larger than the pipes 4, are also likely to be somewhat more vulnerable.

Whilst, as described above, the pipes 4 may simply be held in place in engagement with the respective supporting surface by their own weight, with location of the pipes relative to one another being assisted by interengagement between the longitudinal ribs and grooves on adjoining pipes, in certain instances, for example where a group of pipes 4 arranged side by side are required to follow a bend while remaining at the same spacing from one another or in contact with one another, or where the pipes are particularly vulnerable to being dislodged, it may be desirable to have some additional means of retaining adjoining pipes 4 relative to one another.

Various means may be utilised to this end as discussed in more detail below.

As shown in Figure 8, adjacent pipes 4 may be held together by lacing 100 which may simply be interwoven with the pipes 4 as shown in Figure 8 and appropriately tied (not shown) or adjacent pipes 4 may be held together, as shown in Figures 9 and 10 by connecting strips each comprising an upper and a lower length oftape 101 and 102 respectively extended transversely relative to the pipes 4, above and below the pipes, the superimposed tapes 101 and 102 being secured together, in the locations between adjoining pipes 4, as indicated at 103. (See Figures 9 and 10).For convenience, the connecting strip, comprising the tapes 101 and 102, secured together at intervals, is preferably preformed, preferably as a continuous length, and in use, a length of the strip, appropriate to the array of pipes 4 to be held together, is cut from the strip and the respectiive pipes threaded through the respective pockets defined between the tapes 101 and 102 between adjoining locations 103 at which the tapes 101 and 102 are secured together before the respective ends of the pipes 4 are secured to the appropriate manifolds, or, for example as mentioned below, to further pipes 4. It is a simple matter to slip the connecting strips along the array of pipes 4 to the appropriate position afterthe pipes have been threaded through their respective pockets.

The securing together of the tapes 101 and 102 at intervals 103 may be effected by any suitable means, for example by stitching, but it is preferred to form the tapes 101 and 102 of thermoplastic material, for example to utilise flexible PVC tape for the tapes 102 and 103, with the superimposed plastics tapes 101 and 102 being simply welded together at the locations 103, for example by a spot welding technique.

The connecting strip may thus be readily produced and supplied in a continuous roll from which desired lengths may be cut off.

Another means by which adjoining pipes 4 may be held together in the desired relationship with respect to one another at a particular location is simply by glueing the adjoining pipes 4 together by interposing a respective blob of PVC cement between each pipe 4 and the adjoining pipe 4 at the desired location.

Another technique which may be employed is simply to secure the pipes 4 to a transversely extending backing strip, for example by cement or by welding.

Another technique which may be employed is to connect adjoining pipes 4 by means of continuous strips of PVC cement extended longitudinally in the interstices between adjoining pipes 4 so that each pipe is connected with the adjoining pipes 4 along its whole length. Where it is desired to separate the pipes so connected, for example at the ends, it is possible, by the application of some force, to separate the pipes along the adhesive connection therebetween.

As a variation of the general form of solar energy collector described with reference to Figures 1 to 7, it may be convenient to provide arrays of pipes 4, already connected together side by side by any of the techniques described, as standardised modules.

Thus, for example, a typical such module may comprise a predetermined number of pipes 4 of a predetermined length connected side by side, so that when the module is laid flat it forms a straight, rectangular section of mat, elongate in the longitudinal direction of the pipes. Conveniently one or more such modules may be supplied as a package, in which the mats are rolled, about longitudinally extending axes, around the corresponding manifolds 1,2 etc. Modules of the above-mentioned "straight" type may be provided in several "standard" lengths. Successive such modules may be connected end to end as desired, (and also, of course, such modules or a plurality of series of such modules may be connected in parallel between appropriate manifolds as desired) to achieve a desired layout.Further modules might be provided incorporating bends of predetermined angles, for example, various modules might be provided in the form of a quarter circle (90 bend) or in the form of a half circle (180 bend), of various radii, so that a variety of different layouts may be catered for by utilising different combinations of such modules.

Preferably the different modules are of the same breadth, incorporating the same number of pipes 4 disposed side by side, so that successive modules may be readily connected in series, end to end, with a simple connection between the end of each tube of such a module and the end of a corresponding tube at the adjoining end of the adjoining module, The connection of adjoining said modules, placed end to end, in series, is conveniently effected by fitting adjoining ends of each pair of adjoining pipes 4 to be connected over respective ends of a respective tubular connecting stub of a semi-flexible nature. It is desirable that such connecting stubs should be semi-flexible in order that the collector should retain its flexibility and toughness in the region of the junctions between adjoining modules.

Where a modular system such as that referred to is adopted, it may even be convenient to form at least some modules, for example the straight modules, as lengths of a continuous extrusion, for example in flexible PVC, each such extrusion comprising, in effect, a plurality of parallel adjacent pipes 4 interconnected by thin integral webs, so that the module may be readily rolled up longitudinally as with the modules described previously. With such an arrangement, adjoining pipes 4 may, if desired, be separated by tearing or slitting the module along the respective flexible web.

The modular system referred to has numerous advantages.

For example, many domestic swimming pools are of a standardised design reproduced in large quantitities, and it is envisaged that the most commonly preferred arrangement of a solar collector as described for heating such a swimming pool will be as a pool surround. It would thus be possible for standardised solar collector layouts to be used for such standardised pools, with each layout comprising modules of only a few standard types, allowing for the economy of manufacture obtainable by mass-production techniques.

Another advantage of the modular approach referred to is that the modules can be readily rolled up into a compact and manageable form, with each module maintaining its integrity, for ease of transportation and handling, so that, for example, the task of laying such a collector on an acutely sloping surface, such as a roof or a bank, is considerably simplified.

In addition to the described use of the assemblies described as solar energy collectors for heating swimming pools, it will be appreciated that the constructions described with reference to the drawings may also be utilised for other purposes.

Thus, quite apart from the various uses to which solar energy thus collected may be put, besides that of heating swimming pools, it will be appreciated that the solar energy collector described may be regarded as a species of heat exchanger, in which radiant heat is used to heat a fluid passing within the collector. Such a heat exchanger is referred to herein as a radiant heat exchanger. It will also be appreciated that the same structure may also be used as a conductive heat exchanger, e.g. for heat exchange between fluids, for example by immersing the assembly within a fluid and cooling or heating the latter fluid, or (which is effectively the same thing) heating or cooling respectively the fluid circulated through the assembly. Similarly the structures described may be used for heating or cooling granular or solid bodies.

Among the various fields in which the structures described, or similar structures, may be used, whether as solar energy collectors or radiant or conductive heat exchangers are: the preheating of water by solar energy, in industrial applications, for heating to promote micro-biological processes, such as fermentation, digestion of animal wastes etc., for example as a slurry tank heat exchanger, for horticultural and agricultural heating, for example as a soil heating mat for plant growing, or for providing the heat required in air-drying processes, for example for agricultural crop drying or for air drying and air conditioning.

The pipes 4 in the preferred embodiments described are preferably of relatively large bore, e.g.

5/8", and may be of any suitable inexpensive plastics material such as PVC.

Whilst, in the arrangement described with reference to Figures 1 and 2, adjoining pipe sections 5 in a manifold 1 or 2 are connected with one another by short plastics sleeves fitted over the adjoining end parts, this arrangement has the disadvantage that even when these plastics sleeves are made as short as is practicable, their use makes inevitable short gaps in the series of spigots 6 extending from the manifold. To avoid this disadvantage, it is possible to interconnect adjoining pipe sections 5 by means of lengths of rigid connecting pipe, such as indicated at 120 in Figure 11, which are a close sealing fit within the respective pipe sections 5.Each length 120 of connecting pipe has approximately half of its length engaged within one of the two pipe sections 5 connected thereby and the remainder of its length engaged within the other of the two pipe sections connected, the two sections 5 thus abutting end to end in axially aligned relationship as shown. Each length 120 of connecting pipe extends over a length greater than the pitch between adjoining spigots 6, but the series of spigots is not interrupted because, over the region over which the connecting pipe 120 extends transverse bores to accommodate spigots 6, 6a are still formed through the walls of the respective pipe sections and corresponding aligned bores are formed through the wall of the connecting pipe 120.

The spigots over the region of connecting pipe 120 may be of the same length as the other spigots, and similarly disposed, as indicated at 6a, with the aligned transverse bore in the pipe 120 simply affording a communicating passage with the bore of the conduit, or, as indicated at 6b, the spigots over the region of the connecting pipe may project into the respective transverse bores in the connecting pipe, thereby to assist in retention of the latter. In either case the connecting pipe is preferably retained in the pipe sections 5 by friction and/or by a suitable adhesive. The transverse bores in the connecting pipe may be drilled prior to assembly and located so as to secure the desired alignment with the spigots or the spigot bores, or may be formed after assembly, by drilling by means of a drill extended longitu dinallythrough the spigot bores, or preferably, where the pipe sections 5 with spigots 6 are preformed, through the bores of the spigots 6.

Claims (14)

1. A radiant or conductive heat exchanger comprising an inlet manifold, an outlet manifold and a plurality of flexible pipes connected in parallel between said inlet and outlet manifolds, at least the major part of the solar energy-collecting surface of the collector being constituted by the surfaces of said flexible pipes.

2. A heat exchanger according to claim 1 wherein the mean spacing between adjoining said flexible tubes is less than the diameter of said tubes.

3. A heat exchanger according to claim 1 or claim 2 wherein each said manifold comprises at least one larger pipe section which is substantially more rigid than said flexible pipes, is of substantially greater diameter than said flexible pipes, and has extending laterally from it a plurality of hollow spigots, sealingly fitted in the wall of the larger pipe section and in communication with the interior of the larger pipe section, each said spigot having an end portion of a respective said flexible pipe fitted over its free end and sealed with respect thereto.

4. A heat exchanger according to claim 3 wherein each said manifold comprises a plurality of such larger pipe sections interconnected in series.

5. A heat exchanger according to claim 4 wherein said larger pipe sections interconnected in series are interconnected by means of lengths of flexible piping of substantially the same diameter.

6. A heat exchanger according to any preceding claim wherein said flexible pipes connected in parallel between said inlet and outlet manifolds, are formed externally with longitudinally extending ribs.

7. A heat exchanger according to any preceding claim, wherein at least a group of said flexible pipes extending side by side are physically interconnected via transversely extending linking means attaching each said pipe of said group to the adjacent said pipes of the group.

8. A heat exchanger according to claim 7 wherein said transversely extending linking means com prises a flexible strip formed by two superimposed flexible tapes secured to one another at intervals along the strip to define, in said intervals, respective pockets between the tapes to receive respective said pipes of said group.

9. A heat exchanger according to claim 8 wherein said tapes are of a heat-fusible plastics material and the tapes are secured to one another at said intervals by welding.

10. A heat exchanger according to claim 7 which comprises a plurality of modules each comprising a said group of flexible pipes flexibly connected to one another by such linking means.

11. A heat exchanger according to any preceding claim which takes the form of a solar energy collector.

12. Aswimming pool installation incorporating a circulation and filtration system and further incorporating a solar energy collector according to any of claims 1 to 5, said manifolds being connected with said circulation and filtration system.

13. A heat exchanger substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

14. Any novel feature or combination of features described herein.