GB2046397A

GB2046397A - A retaining rail for securing heating pipes of an under-floor heating system

Info

Publication number: GB2046397A
Application number: GB7930124A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-03-29
Filing date: 1979-08-30
Publication date: 1980-11-12
Also published as: FR2452676A1; NL7904630A; IT7912642A0; BE877207A; DE2912523A1; IT7915214V0; GR62845B; LU81206A1; ES243983U; PT69813A; SE7904987L; IT1124106B; ES243983Y

Abstract

A retaining rail of generally U- shaped configuration but formed as a box-profile extrusion from plastics material is described. The extrusion includes a base and side flanges the upper regions of which are solid but the base and lower regions of which are formed with elongate cavities which extend along the length of the extrusion. Cavities (20) are formed in the flanges and cavities in the base. Circular cut-outs (28) are formed in the side flanges to receive heating pipes (32) which are laid transversely to the length of the rail. The inwardly directed projections (30) grip the pipes (32) and retain them in place. The pipes are not laid in every pair of cut-outs but for example only in alternate cut-outs according to the local heat requirements so that the exposed cut- outs allow flooring compound to flow through the openings in the walls of the cut-outs into the cavities so as to assist in embedding the extrusion within the flooring compound. <IMAGE>

Description

SPECIFICATION A retaining rail for securing heating pipes of an under-floor heating system Field ofinvention The invention concerns under-floor heating systems and in particular a retaining rail for securing in place the heating pipe or pipes of such systems.

Background to the invention In the production of floor heating systems, heating pipes consisting usually of a flexible plastics material are laid on the floor and the under-floor of a room which is to be heated. This laying process involves, according to a certain method, the looping and bending and running ofthe pipe up and down the length of the floor. The individual lengths of the loops are placed at a certain distance from each other, which is calculated in accordance with local heating requirements and the location of cold regions due to windows and the like. This means that the heating pipes must be laid according to a specific design and be appropriately secured. For this purpose the use of clamps or so-called clips is recognised. These clips are pressed onto steel or plastic rails laid overthe under-floor.Other clips are pressed onto bars of steel, mats or grids. The clips, for their part, have cut-outs in which the heating pipes are laid. After the rails have been laid, the clips pressed onto the rails, and the heating pipes laid, the whole construction is covered with a flooring compound which may be concrete-based but additionally may include fillers.

The method using plastic clips on steel rails and described in (AT PS 326 869) offers a good solution to the problem in question. The steel rails have somewhat the same characteristics of expansion and contraction as the flooring compound. There is a disadvantage, however, in the high cost of steel.

There is a further disadvantage clips must be pressed into place. In addition, the cutting of the steel rails into lengths, and the application of the individual clips requires a lot of time. This method of laying, therefore, is qualitatively good, but very high in labour costs.

According to another known laying method, the plastic clips are pressed onto rails which are also of a plastics material. Such plastics rails are cheaper than steel rails. They are also easier to cut into lengths.

They have a very definite disadvantage however in that the plastics material has a different expansion and contraction characteristic from the flooring compound. With variations of temperature, therefore, tensions arise between the plastics rails and the flooring compound. Furthermore, as with steel rails, the spacing between the plastics clips must still be individually measured and the latter individually pressed onto the rails.

With another known securing method, use is made of rails of open U-profile, extruded from solid plastics material. Such rails have apertures or holes in their flanges across the line of the rail, in which the heating pipes are laid. These rails are not, however, distortion-free. They are unable to meet or absorb the forces which occur when laying and securing the heating pipes in position. They dislocate or displace themselves from their ideal position. In many cases, therefore, they are fastened to the floor with screws or bolts. When a flooring compound is used, however, this is not possible. Such rails therefore are found to twist and turn so much that the heating pipes which are laid in the apertures or cutouts are likewise pulled out of position and indented against the sharp edges of the apertures or cut-outs. Later on, leaks occur at these places.Thus these U-profile rails can only be used for heating pipes which are of small dimensions and made of soft material. Uprofile rails are, moreover, unsuitable for use with a flooring compound since, due to their large crosssection and large surfaces, they interfere with the structure of the floor. The latter cracks along the line of the rails and breaks up.

In the present state of the technology, therefore, there is no tube supporting rail which is both cheap in material and production costs and simple to lay.

Further, there is no rail which avoids the formation of cracks in the floor layer formed from a flooring compound and which, in practical use, has the same expansion and contraction characteristics. Finally, the ideal retaining rail should permit all the possible pipe laying to be within a 50mm grid.

Object of the invention It is an object of the invention to provide a retaining rail which is inexpensive to manufacture and lay, has appropriate stiffness and freedom from distortion, will absorb expansion and contraction due to differences in temperature/expansion characteristics of the flooring compound and the retaining rail, and lends itself to the unhampered laying of the heating pipes.

The invention According to the present invention, in a retaining rail of the type adapted to receive and support transversely running heating pipes, the retaining rail is extruded as a U-shaped box-profile having a base and two upstanding side flanges, and apertures are formed in the flanges to receive the pipes by removing material at intervals along the flanges.

A box-profile employs only a small volume of material and is therefore a low cost and light in weight. However such a section has a high resistance to bending and considerable freedom from distortion. The requirements of low cost and ease of laying, without additional screws or bolts, and thus fulfilled.

As a result of its great firmness against distortion, moreover, relatively stiff heating pipes can be held in place and protected against indentations at the points of contact with the apertures. Waste material removed to form the apertures can be recovered and used again.

At first sight a near solution to the problem is offered by an injection-moulded retaining rail. Practically any desired shape can be produced by injection moulding. For the purpose of the invention, however, the retaining rails must be approximately two to four metres in length. Machines and forming tools for the injection of such rails are however not normally available on the market and would first have to be developed at high cost. The only practical solution, therefore, is to extrude the retaining rail as a box-profile, as provided by the invention.

In one preferred embodiment the box-profile cross-section is divided internally into a plurality of cavities which run the length of the extrusion. The partitions which form the cavities increase the resistance of the rail to distortion still further.

Preferably the inner facing sides of the side flanges are inclined and slop inwardly. In this way the resistance to bending is markedly increased without increasing the volume of material used.

In a further preferred embodiment each of the cut-outs comprises the greater part of a circle in section. The entrance to each cut-out is thus defined by a pair of inwardly directed projections. This results in an under-cut into which the heating pipes can be pressed from above and in so doing are somewhat compressed. After the diameter of the pipe has been reduced to allow it to pass the two inwardly directed projections, the pipe springs back to its original diameter and fills the cut-out. The heating pipes are thus snapped into place and held there.

After the extrusion of the box-profile, the cut-outs are made, according to another feature of the invention, by drilling or milling at an angle of 90" to the line of the retaining rail. The waste material thus occurring can, as mentioned, be re-used. It is advantageous if the cut-outs are spaced at 50mm centres so that a 50mm rid of pipes and rails can be formed, if desired.

According to another feature of the invention the upper section of each side flange is solid whilst the base and the lower sections of the flanges are hollow by the formation of one or more cavities. The centres of the circular cut-outs preferably lie in the upper, solid sections of the flanges. The solid flanges provide a high resistance to forces exerted on them by the insertion into the cut-outs of relatively still heating pipes. Distortion of the retaining rails can thus be eliminated. As a result of making the upper parts of the flanges solid, the heating pipes when pressed into the cut-outs move past closed surfaces rather than sharp edges, as would be the case if the flanges were hollow. In this way no damage to the heating pipes occurs.

According to another preferred feature of the invention the cut-outs extend into the partitions defining the cavities under the flanges, such that the partitions are only chamfered by the cut-outs and thus remain as closed surfaces. Sharp edges, which could damage the heating pipes, are thus avoided.

The cavities in the lower sections of the flanges are, however, opened up by the cut-outs. When the retaining rails are covered over with flooring compound the latter flows into the exposed cavities which are not covered up by a heating pipe lying in the cut-out. In this way the flooring compound becomes anchored not only in the cut-outs but also in the neighbouring cavities into which it flows, along the whole length of the rail. Thus tensions between the flooring compound and the retaining rail, which are caused by different temperature coefficients of expansion, are absorbed at each open cut-out. Expansions and contractions occurring in stages in the retaining rails do not accumulate over the length of the rail and cracking of the flooring along the retaining rails is thereby prevented.

In a preferred form of the invention the thickness of a partition between a cavity in the base and a cavity in a side flange is approximately twice the thickness of a partition between the adjoining cavities in the base, and the cut-outs project, by up to half the thickness thereof, into the first-named partitions. In this way the partitions between the cut-outs and the cavities in the base remain as closed surfaces in spite of the cut-outs.

The cross-section of the base is preferably divided up into four cavities. In this way the base also possesses a high degree of freedom from distortion.

As previously mentioned the cut-outs are conveniently arranged at regular intervals along each of the flanges, typically at 50mm spacings.

The invention will now be described by way of example with reference to the accompanying drawings.

In the drawings Figure 1 is a perspective view of an extruded retaining rail before the apertures to receive the pipes have been cut out, Figure 2 is a perspective view of a finished retaining rail complete with cut-outs and with a heating pipe in place, Figure 3 is a longitudinal section along the line Ill-Ill in Figure 2, Figure 4 is a cross-section along the line IV-IV in Figure 2, Figure 5 is a cross-section along the line V-V in Figure 2, Figure 6 is a view from above of the retaining rail with a heating pipe laid in place, Figure 7 is a perspective view of an under-floor with retaining rails put down and heating pipes laid in place, Figure 8 is a section through a finished floor with the layer of flooring compound laid over the pipes and rails, Figure 9 is a corresponding section before the layer of flooring compound has been laid, and Figure 70 is a section corresponding to Figure 8 to a larger scale.

Detailed description of the drawings Figure 1 shows the retaining rail 12 with its base 14 and the two flanges 16. The flanges 16 have inner walls 18 which slope inwards. Each flange 6 has in its lower part a cavity 20 and its upper part 22 is solid.

The base 14 is divided by several partitions 24 into cavities 26. A partition 24 of approximately double thickness separates the cavities 20 of the flanges 16 from the cavities 26 of the base 14.

Figure 2 shows the cut-outs 28. At the top the cut-outs 28 are partly closed by inwardly directed projections 30. At the bottom the cut-outs 28 extend to approximately half the thickness of the partitions 24 enclosing the cavities 20 from below.

Figures 3 to 6 show further views of the retaining rail 12. These figures show a heating pipe 32 which has been pressed into two cut-outs 23. Figures 3 to 6 show particularly clearly that when being pressed into the cut-outs 28, the heating pipe must be compressed as it passes between the projections.

Before reaching its final position the heating pipe 32 can, however, expand again and assume its full circular section. It lies within the confining surfaces of the cut-outs 28, which are solid in the upper part 22, and is held by these securely and with no identation effect.

Figure 7 to 10 show the arrangement of the retaining rails 12 and the heating pipe 32 on a supporting under-floor 34. The first part of the layer process is shown in the illustration represented by Figures 7 and 9. A layer of flooring compound 36 covers the assembly. This is covered with floor plates 38 or similar. In the example illustrated heating pipes 32 lie in every third cut-out 28. The two cut-outs 28 in between are left open. The flooring compound flows in the direction of the arrows shown in Figure 10, through the openings at the bottom of the cut-outs 28, into the cavities 20 of the flanges 16. In this way the compound becomes embedded and clamped into the retaining rails 12 and is supported on the surfaces of the solid parts 22 of the cut-outs 28. This all acts against the formation of cracks in the flooring compound when it has set hard.Forces arising out of different coefficients of expansion of the flooring compound and the plastics material of the retaining rails are absorbed by the anchoring of the flooring compound within the closely adjoining cut-outs.

With reference to Figures 1 and 2, mention must again be made of the stiffness and freedom from distortion which are achieved with the profile of the retaining rail. Forces which act on the flanges 16 in a horizontal direction are restricted by the high resistance moment of the solid upper part 22 and also by virtue of the fact that the outer walls and the sloping inner walls 18 of the flanges are relatively far apart from each other. Forces acting in a vertical direction are restricted, in addition, by the walls and cut-outs confining the outer cavities 26. The partitions 24 and cut-outs which confine the cavities 26 of the base 14 also act against torsional forces. With little use of material and thereby little weight, the retaining rail achieves optimal solidity.

Claims

1. A retaining rail for receiving and supporting transversely extending heating pipes of an underfloor heating system characterised in that the retaining rail is extruded in plastics material as a U-shaped cross-section box-profile with a base and two side flanges and pipe-receiving cut-outs are made by removing material from the flanges at intervals along the length of the rail.

2. A retaining rail as claimed in Claim 1 in which the box-profile forming the retaining rail is divided into cavities by a plurality of partitions.

3. A retaining rail as claimed in Claim 1 or 2 in which the flanges have inwardly sloping inner walls.

4. A retaining rail as claimed in Claims 1,2 or 3 in which the cut-outs are circular and are intersected by the upper surface of the flange so as to provide an opening through which a pipe can be pushed into the cut-out, the opening being defined by inwardly directed projections.

5. A retaining rail as claimed in Claims 1 and 4 in which the cut-outs are formed by driliing or milling.

6. A retaining rail as claimed in any of Claims 1 to 5 in which an upper section of each flange is solid and the lower section of each flange is hollow and the centre of each circular cut-out lies in the solid upper part, and the cut-out extend into but not beyond a partition situated between a cavity in the base and a cavity in the flange.

7. A retaining rail as claimed in Claim 6 in which the said partition between a cavity in the base and a cavity in the flange is twice as thick as a partition between two cavities in the base, and the cut-out projects up to halfway into the thickness of the said partition.

8. A retaining rail as claimed in any of Claims 1 to 7 in which the base is divided up into a plurality of cavities.

9. A retaining rail as claimed in Claims 1 to 8 in which the cut-outs are arranged at constant intervals along the length of the rail.

10. Aretaining rail for heating pipesofan under-floor heating system, constructed and arranged substantially as herein described with reference to and as illustrated in Figures 1 to 6 of the accompanying drawings.

11. An under-floor heating system constructed and arranged substantially as herein described with reference to and as illustrated in Figures 7 to 10 of the accompanying drawings.