The present relates to a solar tubing assembly and to a method of preparing such a solar tubing assembly.

Worldwide there are a number of pre-lagged (during manufacture) flexible tubing products specifically designed for solar applications. These systems typically use corrugated stainless steel tubing (CSST), although it would be possible to use some other material designed for the conveyance of a fluid, such as a flexible plastic, or other flexible metals such as annealed copper.

The tubing is then covered in (i.e. by having a material extruded over the tubing), or is passed through pre-manufactured lengths of, an insulating material. This material is typically ethylene propylene diene monomer (EPDM) rubber, but could also be nitrile rubber ( BR), Aerogel, or any insulating material that can be used to lag tubing and prevent thermal heat loss to the outside environment. This insulating material is then covered in a more durable plastic outer cover to prevent against wear and tear, it is also typically UV stable to prevent degradation from the sun.

Many businesses have expanded on the above product to manufacture a "twin", all in one, feed/return system for a solar collector. This product has two sets of tubing, for example, one to supply fluid from the heat exchanger/hot water tank to the solar collector, the other to return fluid form the collector to the heat exchanger/hot water tank. These types of product further incorporate two sets of insulating material that is then covered in a durable outer cover that also holds the two sets of tubes and insulation together. These products typically also include a sensor cable that is incorporated into the product between the outer cover and the insulation cover.

A typical embodiment of existing twin solar tubing is shown in Figure 1. (1) is the passage which would be occupied by the CSST, either by being passed through or having the EPDM extruded over the tubing. (2) is the EPDM insulation cover, typically of between 10-25mm thick. (3) is a durable outer cover. (4) is the sensor cable incorporated into the product between the outer cover and the insulation. (5) is where the outer cover has been manufactured so that it is pressed or moulded or joined together between the two sets of EPDM. This allows for the feed and return lines to be split, by cutting along this joined section lengthways up the tubing. This is necessary as the feed and return lines will typically be connected to the water tank or the solar collector at opposing locations, for example at opposite sides of the solar collector. The advantage of having the outer cover pressed together in the middle, like at (5), is so that when a cut is made lengthwise in the tubing each "split" single tube & EPDM insulation is still completely protected by the durable outer cover, i.e. the entire circumference of the insulation is still covered by the outer cover.

The disadvantage of this method is that manufacturing the outer cover with the joint section in the middle, like at (5), is reasonably hard to do and adds extra cost to the overall cost of production. Another disadvantage of this embodiment is that the sensor cable must be incorporated into the manufactured product, in this case in-between the outer cover and the EPDM insulation, which adds even further additional manufacturing effort. A further disadvantage of this embodiment is that due to the manufacturing processes involved addition of markings to the outer cover will have to be completed after the product is completed. Printing a circular surface like this typically requires the use of in line ink jet printing, which can be expensive.

Another embodiment of existing solar tubing is shown in Figure 2. (6) is the passage which would be occupied by the CSST, either by being passed through or having the EPDM extruded over the tubing. (7) is the EPDM insulation cover, typically of between 10-25mm. (8) is the durable outer cover. (9) is the sensor cable incorporated into the product between the outer cover and the EPDM insulation. This product incorporates two sets of CSST within one larger piece of EPDM insulation covered in a durable outer cover. The installer must then "split" the product by cutting lengthwise through the outer cover and the EPDM insulation like in Fig 3.

This means that there is now an exposed section of EPDM, shown by (10). Disadvantageously, this exposed section is now exposed to the outside environment and the installer would have to provide additional protection, either by using a plastic sleeve over the exposed "split" portion, or by taping up the exposed section. Cutting through thick lengths of insulation also requires additional work by the installer. Another disadvantage of this embodiment is that the sensor cable must be incorporated into the manufactured product, in this case in-between the outer cover and the EPDM insulation, which requires additional manufacturing effort.

The present invention therefore seeks to provide a solution to these problems. According to a first aspect of the invention, there is provided a solar tubing assembly comprising first and second solar heating fluid circulation elements; each of the first and second solar heating fluid circulation elements having a conduit for the passage of a solar-heatable heat transfer fluid, an insulator which surrounds the conduit, and an insulator cover which surrounds the insulator; and an engagement cover which engages the first and second solar heating fluid circulation elements.

Preferable and/or optional features of the first aspect of the invention are set forth in claims 2 to 10, inclusive.

According to a second aspect of the invention, there is provided a method of producing a solar tubing assembly for the passage of a solar-heatable heat transfer fluid by utilising a plurality of single insulated solar conduits, whereby a common production line can be utilised for manufacturing single and multiple insulated solar conduits, the method comprising the steps of: a] providing first and second single insulated solar conduits adjacent to each other and in parallel; and b] interengaging the first and second single insulated solar conduits together using an engagement cover. According to a third aspect of the invention, there is provided a method of producing a solar tubing assembly in accordance with the first aspect of the invention, for the passage of a solar-heatable heat transfer fluid by utilising a plurality of single insulated solar conduits, whereby a common production line can be utilised for manufacturing single and multiple insulated solar conduits, the method comprising the steps of: a] providing first and second single insulated solar conduits adjacent to each other and in parallel; and b] interengaging the first and second single insulated solar conduits and the sensor cable together using an engagement cover.

Preferable and/or optional features of the second and third aspects of the invention are set forth in claims 14 to 21, inclusive. Furthermore, the methods in accordance with the second and third aspects of the invention may utilise two or more single insulated solar conduits.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic perspective view of a first arrangement of a solar tubing assembly known in the art;

Figure 2 is a schematic perspective view of a second arrangement of a solar tubing assembly known in the art;

Figure 3 is another schematic perspective view of the solar tubing assembly of Figure 2 that has been split lengthwise, thus exposing an insulating material;

Figure 4 is a schematic perspective view of a solar heating fluid circulation element of a solar tubing assembly, in accordance with the current invention;

Figure 5 is a schematic perspective view of a solar tubing assembly, in accordance with the current invention; and Figure 6 is a schematic perspective view of the solar tubing assembly of Figure

5 that has been split lengthwise, thus exposing two solar heating fluid circulation elements of Figure 4 and a sensor cable.

Referring to Figures 5 and 6, there is shown an embodiment of a solar tubing assembly in accordance with the current invention. The present invention also relates to a manufacturing process that has a number of advantages over existing manufacturing methods whereby two fully manufactured sets of "single" tubing (as described in Paragraph 1 and shown in Fig 4) are arranged side by side as shown in Fig 5 and then wrapped by a 2 ^nd protective cover that holds the two single sets together converting 2 single solar product sets into a "twin" feed/return product. "Single" solar tubing is shown in Fig 4, where; (11) is the passage which would be occupied by the CSST, either by being passed through or having the EPDM extruded over the tubing, (12) is the EPDM insulation cover, typically of between 10- 25mm and (8) is the durable outer cover. The durable cover (of the single solar tube) encompasses the entire EPDM insulation so that the entire circumference of the "single" EPDM is protected.

With reference to Fig 5, with these 2 x sets of single solar tubing being arranged side by side, both sets are then covered with an additional durable outer layer (15) that covers both single sets and holds the two together, thus turning two single products into a "twin" product. The sensor cable (14) can simply be laid in the space created between the outer cover of the single products (13) and the outer cover that hold the two single sets together (15). Thus there is no need to incorporate the sensor cable into the manufacture of the twin product itself or incorporate it into the space between the insulation and the outer cover, which would cause additional work during manufacture.

It is anticipated that the outer plastic cover will be wrapped around the two sets and then heat bonded along the seam shown by (16) however other methods, such as heat shrink plastic, could also be used to manufacture the 2 ^nd outer layer. A significant advantage of the invention over previous embodiments is that it easily coverts two fully completed single solar products into a twin product by means of a relatively simple manufacturing process (i.e. the addition of a 2 ^nd outer layer). As companies generally need to provide both a single and twin product manufacturers producing existing twin products would need two different production lines, one to manufacture the single, the other to manufacture the twin. At the very least they would require different machinery to complete the different single and twin covers.

A further advantage over the embodiment shown in Fig 1 is that a desired length of the 2 ^nd outer cover can be removed easily using a utility knife revealing two fully protected single sets of tubing (with their own covers). Thus the product can easily be "split" where necessary for installation to the water tank or solar collector. This is possible without the difficulty of molding or joining two sides of the outer cover together in the middle between the two sets of solar tubing, as shown in (5), which is a difficult and costly manufacturing process.

A further advantage over the embodiment shown in Fig 2 is that the product can easily be "split" by removing the outer cover revealing two single tubing sets that do not need further protection by the adding of a sleeve or taping. There are no exposed sections of EPDM when the 2 ^nd outer cover is removed as the EPDM is still fully protected by the 1st outer cover on each single solar tube set. Advantageously, markings on the 2 ^nd outer cover (17) of the invention could be pre printed while it is still in a flat sheet form which is not possible with previous embodiments. Printing the necessary markings on this outer layer while it is in a flat sheet form is significantly less expensive and easier to produce than producing markings on a curved surface which would typically require the use of in line ink jet printing.

The sensor cable or sensor cables may be in accordance with one or more of the following arrangements: in or embedded within the engagement cover, between the engagement cover and at least one of the insulator covers, in or embedded within at least one of the insulator covers, and/or between the insulator cover and the associated conduit.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.