GB2051293A

GB2051293A - A fixing rail for securing the pipes of an under-floor heating system

Info

Publication number: GB2051293A
Application number: GB7942070A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-06-15
Filing date: 1979-12-05
Publication date: 1981-01-14
Also published as: NL7907283A; IT1124188B; FR2459427A1; PT70359A; IT7912757A0

Abstract

A fixing rail (12) is formed from a plastics material and is laid on a bearing floor (40) for fixing the heating pipes of an under-floor heating system. On its upper face it has recesses (24) at mutual intervals, for accommodating the heating pipes (38). In its lower region reinforcing wires (18) extend in the longitudinal direction. These wires increase the tensile strength of the fixing rail and give it virtually the same coefficient of thermal expansion as that of the composition flooring concrete (42) in which it is embedded. The fixing rail (12) strengthens the concrete and prevents the occurrence of cracks. In a second embodiment the fixing rail (12) has a U-shaped profile and has two flanges extending over the reinforcing wires (18). The recesses (24) for accommodating the heating pipes (38) are moulded in these flanges. <IMAGE>

Description

SPECIFICATION A fixing rail for securing the pipes of an underfloor heating system FIELD OF INVENTION The invention relates to a fixing rail for securing the pipes of an under-floor heating system of the type consisting of an elongate member having transverse slots between upstanding sections of the material running transverse into which are inserted the pipes of the heating system.

Hereinafter the elongate member will be referred to as "a crosspiece".

BACKGROUND TO THE INVENTION To produce an under-floor heating system, heating pipes made of a flexible plastics material are laid in the floor of the room which is to be heated. The lay-out corresponds to a specific layout pattern with coils and curves passing to and fro. The individuai strands of the coils are at a specific distance from each other, calculated according to the local heat requirement and incidence of coldness. This means that the heating pipes are laid out according to a specific laying pattern and must be fixed in this pattern. For this fixing of the heating pipes, a fixing rail has already been proposed which is extruded from plastics as a U-profile. The U-profile itself is used as a framework profile and is equipped with a crosspiece and two flanges, and the recesses are cut or bored into the flanges.A heating pipe inserted in a recess then lies against the walls of the flange. Since the flange walls are not very thick, high surface compression may occur here.

This may lead to dents in the material of the heating pipes. In this proposed fixing rail the chambers formed by the flanges are open to the outside via the cut-out recesses. When the fixing rails are laid on a bearing floor and a coating of composition flooring concrete is applied, the latter runs into the chambers or flanges via the open recesses. According to the reciprocal distance between open recesses, i.e. those in which there is no heating pipe, the composition flooring concrete is anchored by running into the flanges or chambers. This affords the great advantage that thermal stresses, which arise due to the different expansion coefficient of the plastics material from which the fixing rail is made and that of the composition flooring concrete, are absorbed and dispersed. The danger of the formation of cracks is thus excluded to a very great extent.

It is an object of the present invention to improve these two aspects of the proposed fixing rail. Thus the heating pipes should be held without high surface compression occuring, and the fixing rail itself should possess the same thermal expansion coefficient as composition flooring concrete.

THE INVENTION According to the invention, the solution of this problem lies in a fixing rail of the type previously described which is produced from foamed plastics material with recesses moulded therein and reinforcing wires are inlaid in the crosspiece. Thus, the recesses are moulded into the entire material of the fixing rail or in the foamed plastics material from which it is formed. The recesses are thus formed or defined by whole surfaces. A heating pipe inserted in a recess therefore lies with every point on its surface against a wall element of the recess. It is held and supported over its entire surface area by the wall of the recess. High local compression, with the danger that the heating pipe will be dented, does not occur.This is particularly important since heating pipes are being produced from increasingly soft plastics material; so as inter alia to make them easier to lay. Soft plastics material is particularly susceptible to denting. The reinforcement wires inlaid according to the invention in the crosspiece of the fixing rail endow it with the thermal expansion coefficient of composition flooring concrete. Steel and composition flooring concrete have the same thermal expansion coefficient. By moulding the foamed plastics material over the reinforcing wires, the plastics material and the reinforcement wires are bonded so intimately that the reinforcing wires impose their thermal coefficients on the foamed plastics material. Thus, the composition flooring concrete and the fixing rails move the same amount when there are temperature variations.The source of the formation of cracks is therefore no longer present.

Just as in the proposed fixing rail, the composition flooring flows into the open recesses not occupied by heating pipes during coating of the bearing floor. The composition flooring is thus anchored according to the distance between the open recesses. In this way, the fixing rails assume the function of reinforcing the composition flooring.

The fixing rail can fulfil this function fully, as it has been endowed with high tensile strength by the inlaid reinforcing wires. A similar bond is established between the composition flooring and the fixing rail according to the invention as in steel reinforced concrete. In practice it frequently happened that due to bad preparation and/or thermal or mechanical overloading the composition flooring cracked. Then the heating pipes embedded in the composition flooring and running through it had to absorb the stresses which arose.

This frequently led to damage to the heating pipes.

With the fixing rail according to the invention such damage is no longer possible. Even if the composition flooring should crack in a higher layer above the fixing rails and the heating pipes, these cracks terminate at the fixing rails according to the invention and tensile stresses are kept away from the heating pipes.-The reinforcing wires passing through the fixing rails absorb any tensile stresses. Pressure stresses are absorbed by the foam plastics material from which the fixing rails are made. The fact that the fixing rails cannot bend away to the side, since they are embedded in the composition flooring is of further assistance here.

As for the structural design of the fixing rails, in an expedient embodiment according to the invention provision is made for material blocks to be arranged at a reciprocal distance on the crosspiece, for the sides of the material blocks which face each other to form the lateral walls of the recesses, and for them to widen out in the direction of the two longitudinal sides of the crosspiece. Over the entire width of a fixing rail from longitudinal face to longitudinal face the recesses do not therefore have a constant width.

The width is constant only in a central zone. In this zone the heating pipes lie fuliy against the side walls of the recess and are supported over their entire surface by them. Laterally from this central zone the heating pipes lie free, as long as they themselves run straight. However, if they lie in a curve, they also come into contact with the lateral walls of the recesses at their edge zone and are supported there. This improves the fixing of the heating pipes in the fixing rails. Simultaneously, the iocal compression acting onthe heating pipes is reduced.

In detail, in a particular embodiment provision is made for the material blocks to consist of a central area of constant width with pyramids adjoining the two sides of this and extending up to the longitudinal faces of the crosspiece, and for the faces of the central area to define the lateral walls of the recess at a constant distance from each other, and for the side surfaces of the pyramids to define the section which widens out.

The pyramids have a geometrically simple form. In this way neither the production of the mould nor the foaming process in it presents any particular problems in the manufacturing process. Compared with construction of a fixing rail with, for example, a rectangular massive cross-section, the formation or defining of the recesses by a central zone with constant width with the two pyramids adjoining it affords the advantage that there is a great saving of materials. Plastics material is used only at the points where it is required to support the heating pipes.

The heating pipes should rest against the recesses over their entire circumference. In an expedient embodiment provision is therefore made for the base of the recess formed on the upper face of the crosspiece to have a semicircular shape and to flow continuously into the side walls. This transition is effected gradually.

There is no sharp boundary between the base and the side walls of the recess. This means that the heating pipes are supported over their entire circumference.

To achieve still better fixing of the heating pipes, in a further embodiment provision is made for projections to be provided on the upper edge of the side walls, projecting into the recesses. These rest on the heating pipes from above and hold them firmly in the recesses. The distance between the two inner edges of the projections can be somewhat less than the diameter of a heating pipe. Due to the yielding nature of the plastics material which forms both the fixing rail and the heating pipe, a heating pipe which is somewhat larger can also be pushed in past two projections or between two projections, into a recess.

After the fixing rail has been formed in a mould and removed therefrom, the projections are formed by pushing away and/or compressing material from the upper layer of the central zone of the material blocks, under the effect of pressure and heat. For this purpose a heated plate is pressed against the fixing rail. This may equally well be drawn through under a hot roller. The material in an upper edge region of the fixing rail is somewhat compressed by this, and is pressed downwards and inwards into the recesses as the projections are formed.

To improve the bonding between the foam plastics material which forms the fixing rail and the reinforcing wires, the latter are preferably grooved or roughened in some other way.

Advantageously, two reinforcing wires are provided, running along the sides of the crosspiece.

In the first embodiment described above material blocks are moulded on the upper face of the crosspiece at mutual intervals, the blocks enclosing the recesses between them. The opposing sides of these blocks are contoured appropriately. This produces the circular shape of the recesses. The heating pipes are pressed into the latter, fitting tightly. The material blocks are narrower than the crosspieces. Accordingly, the heating pipes also lie against the walls of a recess for only a short distance, corresponding to the width thereof. In many applications this is in advantage. However, there are also applications where the heating pipe should be held and supported over as much of its length as possible.

Such an application arises when the heating pipe is bent into a specific shape in the area outside the fixing rail and is thereby endowed with an inherent stress. So that the heating rail runs in the desired shape despite this inherent stress, it must be held in the fixing rail for the longest possible distance and emerge from it at an angle of 900. This means that the heating pipe does not already assume a curved shape in the recess.

The second embodiment according to the invention serves for this purpose, wherein flanges are provided on the upper face of the crosspiece, extending along its sides over the reinforcing wires and the recesses are moulded in these flanges.

The fixing rail is thereby endowed with the shape of a 'U'. The two flanges and thus also the recesses moulded in them are separated by the width of the crosspiece. Accordingly, the heating pipe is held in the two recesses at two points which are separated from each other, and therefore over a greater distance. The fact that the heating pipe lies free between the two recesses can be overlooked in this case. Thus, while the heating pipe has been previously described as being held in only one recess in the fixing rail, it is preferably held in two recesses spaced out from each other, in the two flanges. As long as the total thickness or width of the two flanges is less than the thickness or width of the material blocks which define the recesses in the earlier described fixing rail there is even a saving of material.It must be taken into account here that the strength and torsional rigidity of the fixing rail does not call for wide flanges. Since these extend on the two sides of the crosspiece and still also run above the reinforcing wires, even narrow flanges provide a high moment of resistance.

The fixing rail is produced from a foamable plastics material. The recesses are formed during this process by inserting cores in the mould.

However, a recess which has a circular shape or an undercut cannot be simply moulded in. To produce the recess, therefore, provision is made according to the invention for slits with parallel walls to be moulded into the flanges and for these to be forced outwards subsequently with a spike.

The invention will now be described by way of example with reference to the two embodiments shown in the Drawings.

IN THE DRAWINGS Fig. 1 is a perspective illustration of a fixing rail according to the first embodiment, with a heating pipe inserted in it, Fig. 2 is a section along the section line Il-I I in Fig. 1 , with a side view of the fixing rail, Fig. 3 is a plan view onto the fixing rail and the heating pipe laid in it.

Fig. 4 is a perspective schematic illustration of a bearing floor with fixing rails laid out on it, with heating pipes inserted, Fig. 5 is a longitudinal section through a fixing rail along the section line V-V in Fig. 4, showing composition flooring concrete already applied, Fig. 6 is a section as in Fig. 5, with the addition of a floor covering, Fig. 7 is a further perspective partial view of the fixing rail showing in particular the reinforcing wires, Fig. 8 is a longitudinal section through the fixing rail before the formation of the projections, Fig. 9 is a longitudinal section through the fixing rail during the formation of the projections by compression of the surface layer, Fig. 10 is a longitudinal section through the fixing rail during the formation of another embodiment of the projections by compression of the surface layer, Fig. 11 is a perspective view of the fixing rail according to the second embodiment, Fig. 12 is a side view looking in the direction of the arrow Xll in Fig. 11, Fig. 1 3 is a plan view onto the fixing rail looking in the direction of the arrow XIII in Fig. 11, Fig. 14 is a perspective view of the fixing rail after removal from the mould still with the parallel-walled slits, before the spike is forced in, Fig. 1 5 is a corresponding view after the spike has been forced in, Figs. 1 to 3 show the fixing rail 12 according to the first embodiment, with its crosspiece 14, the upper face thereof, and the two reinforcing wires 1 8 running through it. In the example shown, these have grooves 20.On the upper face 1 6 of the crosspiece 14 the material blocks 22 are arranged at a reciprocal distance. They are formed integrally with the crosspiece 14. Between them they define the recesses 24. These recesses have a semi-circular base 26, and side walls 28. The projections 30 project inwards from the upper edge of the side walls 28. The material blocks 22 consist of a central region 32 and the two horizontal pyramids 34. These are defined laterally by their side faces 36. They adjoin the side walls 28 via their inner ends. The side surfaces 36 slope away from each other outwards to the edges of the crosspiece 14 and effect a widening of the recesses 24. In the example shown in Figs. 1 to 3, a heating pipe 38 is inserted in one recess. Fig. 4 shows a bearing floor 40, such as the concrete ceiling of a house, for instance, on which fixing rails 12 are disposed.Heating pipes 38 are inserted in these. Fig. 5 shows the same arrangement in cross-section coated with composition flooring concrete 42. Fig. 6 shows the same arrangement with an additional floor covering 44 laid down. This may be made up from individual plastic tiles. In Fig. 7 the two reinforcing wires 1 8 are shown especially. Fig. 7 shows the grooves 20 clearly. These may extend over the whole circumference of the reinforcing wires 18, or only over a part of them. Fig. 8 shows the fixing rail directly after removal from the mould. The side walls 28 still run straight upwards. The projections 30 are not yet present. The formation of these is shown schematically in Figs. 9 and 10. The fixing rail 12 is compressed with a hot plate 46. During this process it lies on a moulding plate 48.Due to the pressure exerted by the heating plate and the simultaneous heating, a surface layer is compressed. The material compressed thereby yields laterally and moves into the recesses 24, forming the projections 30. In the embodiment shown in Fig. 9, the material is compressed slightly below the upper edge of the fixing rail 1 2.

Accordingly, the projections 30 lie slightly below the upper edge of the fixing rail. On the other hand, in the embodiment shown in Fig. 10, the material is compressed right at the upper edge.

The projections 30 are thus also formed right on the upper edge.

After this overall description of the fixing rail according to the invention, some details should be mentioned more particularly. In Fig. 3 a bent heating pipe is shown in dashed lines. With a still tighter curve this would rest at least partly against the side face 36 of a horizontal pyramid 34 and would be additionally supported by it.

A similar picture is shown in Fig. 4. Fig. 4 shows a curve between two strands of a heating pipe 38 which run in a straight line. This bend will also rest partly against the side faces 36 of the horizontal pyramids 34. Figs. 5 and 6 show the composition flooring concrete 42 which has run into the recesses 24 provides anchorage. Thus, thermal stresses arising in the composition flooring concrete 42 are absorbed at these anchoring points and are transmitted to the fixing rails 1 2.

The reinforcing wires 1 8 passing through these absorb and disperse these stresses. Thus, the reinforcing wires 1 8 have the same significance for the composition flooring concrete 42 as the Monier steel in steel reinforced concrete. The intimate bonding between the composition flooring concrete 42 and the reinforcing wires 1 8 is achieved on one hand by its flowing into the open recesses 24, and on the other hand by the grooves 20.

Figs. 2 and 3 also show clearly the projections 30: When a heating pipe 38 is pressed into a recess 24, they yield laterally. After the heating pipe 38 has been pushed in, they rest on it from above.

For the production of the fixing rail 12 according to the invention, any foamable plastics material which simultaneously allows the formation of the projections 30 by the application of heat and pressure is suitable.

Foam substances from the polystyrene and polyurethane groups may be used.

The fixing rail 12 shown in Figs. 11 to 13 consists of a crosspiece 14 with the upper face 16, the two reinforcing wires 1 8 and the two flanges 50 with inner faces 52 which drop away at a right angle towards the inside. The recesses 24 are disposed in the flanges 50. They have bases 26, circular side walls 28, and projections 30 which project towards the inside. The Figures also show a heating pipe 38 inserted in two recesses 24.

The description given above requires no additions. It need only be added that the fixing rails are laid on the bearing structure of a floor, such as a concrete coating, for example. The heating pipes, which are made of a flexible, thermally strong and resistant plastic material, are pressed into the recesses according to a specific plan. After this, the whole is filled in with composition flooring concrete or the like.

Fig. 14 shows a piece of fixing rail in the form in which it leaves the mould. The recesses 24 still have mutually parallel side walls. The spike 54 is forced into them. Due to the compressibility of the plastics foam from which the fixing rail is made, the recesses are widened out thereby, and their side walls assume the circular shape shown in Fig.

15.

References herein to composition flooring concrete are intended to include any composition flooring material which may be concrete or other known stable and inert material.

Claims

1. A fixing rail for the heating pipes of an underfloor heating system, comprising an elongate member having transverse slots between upstanding sections of the material forming the member (hereinreferred to as a crosspiece) in which the pipes are inserted and fixed, in which the elongate member is produced from foamed plastics material and the recesses (24) are moulded therein, reinforcing wires (18) are inlaid in the material of the crosspiece.

2. A fixing rail as claimed in Claim 1, in which material blocks (22) ace arranged on the crosspiece (14) at a reciprocal distance from each other, the facing sides of the material blocks (22) form the side walls (28) of the recesses (24) and widen out in the direction of the two longitudinal sides of the crosspiece (14).

3. A fixing rail as claimed in Claim 2, in which the material blocks (22) consist of a central zone (32) of constant width with horizontal pyramids (34) adjoining this on either side and extending up to the longitudinal sides of the crosspiece (14), the sides of the central zone (32) defining the side walls (28) of the recess (24) at a constant distance from which other and the side faces of the pyramids (34) defining its widening sections.

4. A fixing rail as claimed in any of Claims 1 to 3, in which the bottom (26) of the recess (24) formed on the upper face (16) of the crosspiece (14) is in the shape of a semi-circle, and merges continuously onto its side walls (28).

5. A fixing rail as claimed in any of Claims 1 to 4, in which projections (30) are provided on the upper edge of the side walls (28), projecting into the recesses (24).

6. A fixing rail as claimed in Claim 5, in which the projections (30) are formed by pressing out material from the upper layer of the central zone (32) under the effect of pressure and heat.

7. A fixing rail as claimed in any of Claims 1 to 6, in which two reinforcing wires (18) are provided and these run along the sides of the crosspiece (14).

9. A fixing rail as claimed in Claim 1 in which flanges (50) are provided on the upper face (16) of the crosspiece (14), extending along its sides and above the reinforcing wires (18), and the recesses (24) are moulded in these flanges.

10. A fixing rail as claimed in Claim 9, in which the circular-shapes recesses (24) are produced by forcing out parallel-walled slits with a spike (54).

11. A fixing rail as claimed in Claim 1 constructed arranged and adapted to function substantially as herein described with reference to and as illustrated in the accompanying drawings.