GB2096221A

GB2096221A - Anti-condensation device

Info

Publication number: GB2096221A
Application number: GB8209829A
Authority: GB
Original assignee: REA JOHN TERENCE
Current assignee: REA JOHN TERENCE
Priority date: 1981-04-07
Filing date: 1982-04-02
Publication date: 1982-10-13

Abstract

The frame of an aluminium- framed door or window 3 is fitted with an electrical heating element 2 comprising adhesive-backed aluminium foil strips 4 to which the element 2 is heat welded. Electrical power is supplied to the heating element warming the frame and preventing the formation of condensation. <IMAGE>

Description

SPECIFICATION Anti-condensation devices This invention relates to anti-condensation devices for doors and windows, and to doors and windows fitted with such devices.

Aluminium-framed doors and windows are increasingly used in the construction of new buildings and as replacement doors and windows in existing buildings. However such doors and windows suffer from a major disadvantage where the building is heated in that, when the outside temperature is low, the temperature of the internal surfaces of the aluminium frames will tend to be much lower than the temperature of the surrounding air due to the high thermal conductivity of aluminium, and, under certain conditions, this may cause moisture to condense out of the air on to the internal surfaces of the frames. The condensation may collect in pools at the bottoms of the doors and windows and may cause unsightly stains to flooring and/or encourage the growth of moulds. This problem is particularly acute with double-glazed units.To combat this problem certain aluminium doors and windows are fitted with so-called thermal breaks intermediate the internal and external surfaces of the frames. However, such breaks provide only a partial solution and moreover considerably increase the cost of manufacture of the doors and windows. It is an object of the invention to provide an improved anti-condensation device of low cost.

The invention provides an anti-condensation device for fitting to the frame of a door or window and adapted to increase the temperature of the internal surfaces of the frame when supplied with electrical power from a suitable source, wherein the device comprises an electrical heating element and an adhesive backing for attaching the heating element to the frame.

Preferably the heating element is attached to one side of at least one backing strip and the adhesive backing is provided on the opposite side of the or each backing strip. Where the or each backing strip is a foil strip made, for example, of aluminium, the heating element may be heat sealed to the or each backing strip. Conveniently a respective backing strip is provided for each of four portions of the heating element for attaching the heating element to a respective frame section, and these portions are joined together by further portions of the heating element which are not provided with backing strips.

The heating element may be in the form of a single length of element or may be folded back on itself so as to form two lengths of element which are constrained to run substantially parallel to one another. Alternatively the heating element may comprise a plurality of element sections for fitting to the frame sections, each element section preferably corresponding substantially in length to the corresponding frame section and the element sections being adapted to be electrically connected together when fitted to the frame sections.Such an arrangement has the advantage that element sections may be provided in a number of standard lengths, and a door or window of almost any size or shape may be catered for by selecting two element sections of length substantially corresponding to the height of the door or window and two or three element sections of length substantially corresponding to the width of the door or window.

According to the invention there is provided a door or window having a frame fitted with an anticondensation device in the form of an electrical heating element arranged to increase the temperature of the internal surfaces of the frame when supplied with electrical power from a suitable source.

Where the frame sections are provided with a hollow cavity, as is generally the case with extruded aluminium frame sections, it is particularly convenient for the heating element to run in this cavity, possibly being attached to the wall of the cavity adjacent the internal surfaces of the frame. In this case the element could be fitted during assembly of the frame sections.

Alternatively the heating element could be attached directly to the internal surfaces of the frame, in which case it could be fitted to the frame at any time, even after installation of the door or window.

In order that the invention may be more fully understood, several examples of anticondensation device in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a first exemplary device fitted to a residential door; Figure 2 shows a second exemplary device for fitting to a window; and Figure 3 shows a detail of the device of Figure 2.

Referring to Figure 1 an extruded aluminiumframed door 3 comprising two side frame sections 9 and 10, top and bottom frame sections 1 1 and 12, a mid-rail frame section 13, hinges 14 and a handle 15 is fitted with an anti-condensation device 1 incorporating a heating element 2 for increasing the temperature of the internal surfaces of the door frame when supplied with electrical power from the domestic electricity supply. The heating element 2 is folded back on itself so as to form two lengths 16 and 17 of element which runs substantially parallel to one another. The lengths 16 and 17 of heating element 2 are heat welded to five separate aluminium foil strips 4 which are attached to the frame sections 9, 10, 1 1 and 12 by an adhesive backing.The heating element 2 which is terminated by a two-pin plug 5 at the hinge side of the door 3 may be connected to the supply by a lead (not shown) provided with a socket connector for receiving the plug 5.

Figure 2 shows a modified form of device 1' having a heating capacity of 12.5 Wm- for fitting to an extruded-aluminium-framed window (not shown). In this case the heating element 2' is in the form of a single length 18 of element heat welded to four aluminium foil strips 4' for attaching to the internal surfaces of the top, bottom and two side frame sections of the window. The element 2' is terminated at each end by a length, for example 15 cm, of cold cable 19 or 20 joined to the element 2' at a hot/cold junction 21 or 22. The cables 19 and 20 are brought together and connected to a two-pin plug similar to that shown in Figure 1.The lengths of the strips 4' are chosen to suit the width and height of the window frame to which the device 1' is to be fitted, whereas each of the portions 23 of heating element 2' between the strips 4 which are not themselves provided with backing strips have a length of about 10 cm to enable the element 2' to be bent through a right angle at the corners of the frame.

The structure of the heating element 2' in which the element 2' is shown cut away. A resistive heating wire 24 is wound about an electrically insulating former 25 consisting of a bundle of Nylon or glass fibres 26 and is surrounded by an electrically insulating inner sleeve 27 made of silicon rubber. Both the former 25 and the inner sleeve 27 should be resistant to melting in the event of overheating of the element 2'. The inner sleeve 27 is surrounded by an outer, polyvinyl chloride (p.v.c.) sleeve 28 which provides a second layer of electrical insulation and is heat welded to the aluminium foil strips 4'. The adhesive backing of each of the strips 4' is covered by a protective strip (not shown) which is removed when the device 1' is to be fitted to the frame. The element 2 of Figure 1 is of similar construction to the element 2'.

The device may further comprise a thermostat, incorporating a bimetallic strip, for regulating supply of electrical power to the heating element, thus saving energy without adversely affecting the performance of the device. Alternatively, or additionally, the device may be provided with means for varying the heat output of the device.

For example, the device may comprise two heating elements and a switching unit may be provided for connecting only one of the elements to the power source, for connecting the two elements in series or for connecting the two elements in parallel, thus giving three different heat settings.

In use of such devices it has been found that the formation of condensation on the internal surfaces of the door or window frame or on the glass is prevented when the temperature and humidity within the room are 240C and 85% respectively and the power supplied to the device is about 100 W for an outside temperature down to at least -70C.

Furthermore it has been found that, if condensation has already formed before the device is switched on, then switching on soon causes the condensation to disperse totally.

It should be understood that the abovedescribed devices may be modified in a number of respects without departing from the scope of the invention. For example the heating element need not extend along all the frame sections of the door or window. In a particularly simple form of the invention it may extend only along the bottom frame section. On the other hand, where the device is fitted to a door having a mid-rail, the heating element may extend along the mid-rail as well as along the other frame sections.

Furthermore the device may comprise any number of wires connected in any series, parallel or series-parallel configuration in order to achieve the desired total wattage. If desired, in order to obtain a differential heating effect, the heating capacity per unit length of the heating element may be varied between one or more different values along the length of the element by varying the density of winding of the resistive heating wire 24 on the former 25.

The device may be connected directly to the mains supply or alternatively the supply voltage may be transformed, or otherwise adapted, from the mains voltage to any suitable voltage level.

Claims

1. An anti-condensation device for fitting to the frame of a door or window and adapted to increase the temperature of the internal surfaces of the frame when supplied with electrical power from a suitable source, wherein the device comprises an electrical heating element and an adhesive backing for attaching the heating element to the frame.

2. A device according to claim 1, wherein the heating element is attached to one side of at least one backing strip and the adhesive backing is provided on the opposite side of the or each backing strip.

3. A device according to claim 2, wherein the or each backing strip is a foil strip.

4. A device according to claim 3, wherein the or each backing strip is made of aluminium.

5. A device according to claim 3 or 4, wherein the heating element is heat sealed to the or each backing strip.

6. A device according to any of claims 2 to 5, wherein a respective backing strip is provided for each of four portions of the heating element for attaching the heating element to a respective frame section, and these portions are joined together by further portions of the heating element which are not provided with backing strips.

7. A device according to claim 6, for fitting to the frame of a door, wherein the portion of the heating element for attachment to the frame section incorporating the handle of the door is provided with two separate backing strips for attachment respectively to an upper part and to a lower part of said frame section and separated by a part of the heating element which is not provided with a backing strip intended to be positioned in the vicinity of the handle.

8. A device according to any preceding claim, wherein the adhesive backing is covered by a protective strip which is removed when the device is fitted to the frame.

9. A device according to any preceding claim, wherein the heating element is doubly insulated.

10. A device according to any preceding claim, wherein the heating element is folded back on itself so as to form two lengths of element which are constrained to run substantially parallel to one another.

11. A device according to any preceding claim, wherein the heating element incorporates one or more sections having a different heating capacity per unit length than the remainder of the heating element.

12. A device according to any preceding claim, wherein the operation of the heating element is thermostatically controlled.

13. A door or window having a frame fitted with an anti-condensation device in the form of an electrical heating element arranged to increase the temperature of the internal surfaces of the frame when supplied with electrical power from a suitable source.

14. A door or window according to claim 13, wherein the heating element runs within a hollow cavity in the frame sections.

15. A door or window according to claim 13, wherein the heating element is attached to the internal surfaces of the frame.

16. An anti-condensation device substantially as hereinbefore described with reference to the accompanying drawings.

17. 1 7. A door or window having a frame fitted with an anti-condensation device, substantially as hereinbefore described with reference to the accompanying drawings.