GB2094382A

GB2094382A - Reducing condensation on a window frame

Info

Publication number: GB2094382A
Application number: GB8106393A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-02-28
Filing date: 1981-02-28
Publication date: 1982-09-15
Also published as: GB2094382B; EP0059545A1

Description

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GB 2 094 382 A 1

SPECIFICATION

A window, a method of reducing condensation of water vapour on a window frame structure and a device for use in the method

5 From one aspect, the present invention relates to a method of reducing the condensation of water vapour on a window frame structure from air inside a building incorporating the frame structure. The expression "frame structure" as used herein 10 embraces a frame which is fixed in a wall of a building and embraces a frame around a glazing panel, which frame is movable relative to a wall of the building to enable the window to be opened and closed. The term "window" as used herein 15 embraces glazed doors.

The invention also relates to a device for use in the method and to a window frame comprising a frame structure and one or more glazing panels supported by the frame structure.

20 The frame structure of many windows is made of timber but this material suffers from significant disadvantages, notably shrinkage and warping which lead to a need for considerable maintenance work and may result in a poor fit 25 between relatively movable parts of the window. Steel and aluminium have also been used extensively in the manufacture of window frame structures, these materials avoiding the aforementioned disadvantages of timber but 30 having a relatively high thermal conductivity so that the temperature of the internal surface of the frame structure often falls below the dew point of the atmosphere within the building. This leads to condensation of water vapour on the frame 35 structure which can result in damage to wall and floor coverings and to the growth of organisms on the frame structure. Attempts have been made to reduce condensation on metal window frame structures by incorporating in the frame structure 40 materials having a lower thermal conductivity, for example plastics materials. However, the problem of condensation on window frame structures has not been solved in this way.

According to a first aspect of the present 45 invention, there is provided a method of reducing the condensation of water vapour on a window frame structure wherein an electrically energisable heating element is applied to the frame structures and an electric current is passed through the 50 heating element intermittently.

Energisation of the heating elements may be controlled in accordance with the temperature at a position outside the window or in accordance with the temperature at a position on or within the 55 window frame structure. Thus, the duration of the periods during which the heating element is energised continuously and the duration of the intervals between these periods may be controlled to avoid the temperature at a position on or within 50 the window structure falling below a predetermined value.

According to a second aspect of the invention, there is provided a window comprising a frame structure and one or more glazing panels

65 supported by the frame structure, wherein there is mounted on or in the frame structure an electrically energisable heating element.

According to a third aspect of the invention, there is provided a heating device for use in a 70 method according to the first aspect and comprising a hollow housing, an electrically energisable heating element disposed within the housing, a further electrical conductor disposed within the housing, first and second parts of a 75 two-part electrical connector mounted at spaced positions in the housing and each having a first electrical connector connected electrically with the heating element and a second electrical connector connected electrically with the further 80 conductor, the connector parts being so arranged that the first part can co-operate with the second connector part of an identical device and the second part can co-operate with the first connector part of a further identical device to 85 connect the heating elements of the three devices electrically in series with one another and to connect the further conductors of the three devices electrically in series with one another. Examples of windows embodying the second 90 and third aspects of the invention and an example of a method according to the first aspect will now be described, with reference to the accompanying drawings, wherein:—

FIGURE 1 shows an elevation of a window; 95 FIGURE 2 shows on an enlarged scale a fragmentary cross-section on the line II—I! of Figure 1; and

FIGURE 3 shows a partial cross-section of a modification of the window, on a line 100 corresponding to the line III—III of Figure 1.

The window illustrated in Figure 1 comprises a timber surround 10 which is fixed in an opening in a wall (not shown) of a building. The timber surround extends around the periphery of a frame 105 structure 11 supported by the surround. In turn, the frame structure supports a number of glazing panels which may be formed of glass. The frame structure 11 includes a head 12, sill bar 13, side members 14 and 15 extending between the 110 head and the sill bar, mullions 16 and 17 also extending between the head and the sill bar and transoms 18 and 19 extending each between one of the side members and one of the mullions. All of these parts of the frame structure are fixed with 115 respect to the masonry wall. A glazing panel 20 supported by the sill bar, mullions and the head is also fixed. Below each transom, there is a hinged casement comprising a glazing panel 21 supported in a rectangular frame 22 which 120 constitutes a part of the frame structure. Above each transom, there is a top-hinged rectangular frame 23 supporting a further movable glazing panel 24. The glazing panels shown are double glazed sealed units.

125 The frame structure 11 is formed mainly of aluminium, being assembled from lengths of aluminium extrusions. As shown in Figure 3, the frame structure further comprises resilient seals mounted on the frames 22 and 23 to seal these

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frames to the fixed parts of the frame structure when the panels 21 and 24 are closed.

Marginal portions of each of the glazing panels are received in respective glazing channels defined 5 by the frame structure 11. In Figure 3, a glazing channel defined by the mullion 17 is indicated by the reference number 26 and a glazing channel defined by one of the hinged frames 22 is indicated by the reference numeral 27. Glazing 10 gaskets 28 are interposed between the side walls of the glazing channels and the marginal portions of the glazing panels. These gaskets are tapered to facilitate insertion of the gaskets into the glazing channels after the marginal portions of the glazing 15 panels have been received therein. The seals 25 and gaskets 28 are conveniently formed of neoprene rubber. The remainder of the frame structure 11 is formed of aluminium.

On surfaces of certain parts of the frame 20 structure 11 which face towards the interior of the building, there are mounted heating devices. On each of the side members 14 and 15, there is mounted a heating device 29 which extends approximately from the lower end of the side 25 member upwardly for a distance approximately equal to one third the height of the side member. On each of the mullions 16 and 17, there is mounted a heating device 30 which extends approximately from the lower end of the mullion 30 to the level of the adjacent transom, a distance which is approximately two thirds the height of the mullion. On the sill bar 13, there are mounted three heating devices 31,32 and 33, each of which occupies almost one third of the length of 35 the sill bar. Each of the heating devices 29 to 33 is elongated and rectilinear. The heating device 31 is joined to the adjacent heating device 29 by an angle connector 34 and is joined to the heating device 32 and to the adjacent heating device 30 40 by a connector tee 35. A similar connector and tee are associated with the heating device 33. At the upper ends of the heating devices 30, there are provided end caps 36 and at the upper ends of the heating device 29 there are provided end caps 37. 45 As shown in Figure 2, each of the heating devices 29 to 33 comprises an electrical energisable heating element 38 and a further, insulated electrical conductor 39 disposed within a hollow housing. The housing comprises a base 50 plate 40 and a cover 41 mounted on the base plate. In the particular example illustrated, the surfaces of the frame structure 11 on which the heating devices are mounted are flat and therefore the face of the base 40 which is presented 55 outwardly of the housing is flat.

The heating element 38 is in the form of a length of known heating tape having an electrically conductive core covered by an electrically insulating material. This tape engages 60 the faces of the base 40 which is disposed at the interior of the housing and the base is formed of aluminium or other material which is a good conductor of heat. Between the heating element 38 and the cover 41, there is provided a strip 42 65 of thermally insulating material.

Opposite ends of the housing of each of the devices 29 to 33 are closed by respective plugs which incorporate respective parts of a two-part electrical connector. Each of these parts has a first connector element connected with the core of the heating element 38 and a second connector element connected with the core of the further conductor 39. The connector elements in one plug are in the form of longitudinally projecting pins which can enter complementary sockets formed in the connector elements of the other plug. Thus, each of the devices 29 to 33 has a male plug at one end and a female plug at the other end.

Each of the tee connectors 35 comprises a housing containing two similar, insulated electrical conductors connecting together respective connector elements in each of three plugs comprised by the tee connector. The tee connector does not include an electrical heating element. Each of the end caps 36 comprises a single electrical conductor connecting together connector elements in a single plug of the end cap so that the end cap provides an electrical connection between the heating elements 38 and the conductor 39 of the adjacent heating device 30. Each of the end caps 37 comprises a pair of terminals by means of which electrical leads which pass through the timber surround 10 can be connected to the heating element 38 and conductor 39 of the adjacent heating device 29. If required, an end cap 37 may be provided on one only of the heating devices 29, an end cap 36 being provided on the other heating device 29.

Each of the heating elements 29 to 33 is secured to the frame structure 11 by means of screws (not shown) passing through holes drilled in the base 40. The connectors 34 and 35 may be secured to the frame structure in a similar way. The tee connectors 35 hereinbefore described connect the heating elements 38 of the heating devices 31,32 and 33 in series with one another, the conductors 39 of these devices also being in series with one another, but establish parallel connection of the heating devices 30.

Alternatively, each tee connector 35 may establish series connection of each of the three adjacent heating devices.

It will be noted that an upper part of the frame structure 11 is devoid of heating elements. The aggregate of the lengths of the heating devices 29 to 33 is less than one half the aggregate of the lengths of the components of the frame structure 11 and is preferably less than one third the latter aggregate.

In Figure 3, there is illustrated a modification of the window shown in Figure 2, from which all of the heating devices 29 to 33 and the connectors and end caps associated therewith are omitted, heating elements 42 being mounted on the frame structure 11 within certain of the glazing channels. The heating elements 43 comprise length of known heating tape which lie in face-to-face engagement with walls of the glazing channels. These lengths of heating tape can be inserted in an existing window by removing

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glazing gaskets 28 at selected positions, inserting the heating elements into the glazing channels and then replacing the gaskets. Electrical conductors for conveying current to and from the 5 heating elements 43 may pass between the glazing gaskets and the walls of the glazing channels or may extend through apertures drilled in walls of the glazing channels.

As shown in Figure 3, a heating element 43 10 may be provided in one of the hinged frames 22 and 23. In this case, there are provided on the frame concerned two connector elements (not shown) of respective two-element separable connectors, the other elements of which are 15 mounted on a fixed part of the frame structure 11 to establish electrical contact with the connector elements on the hinged frame when the panel supported by that frame is closed. The two-element connectors may be of a type known for 20 use in burglar alarm systems.

The number and length of heating elements 43 used may be substantially the same as the number and length of heating elements 38 used in the window illustrated in Figure 1, the heating 25 elements 43 being arranged in corresponding positions. However, we have found that where heating elements arranged as shown in Figure 3 are provided, the aggregate length of the heating elements can be somewhat less than the 30 aggregate length of the heating elements provided in the window shown in Figure 1.

It will be noted that each of the heating elements 43 is disposed in a substantially closed, elongated space defined by the frame structure 35 and the glazing panels. When the heating elements 43 are energised, heat is transferred by conduction to the immediately adjacent wall of the frame structure 11 which is preferably adjacent to the interior of the building. Heat is 40 conducted to further elongated air spaces defined by the frame structure, such as the air space 44 indicated in Figure 3. Heat is also transferred directly to air in the glazing channel containing the heating element. The heated air in these enclosed 45 spaces rises by convection to carry heat to parts of the frame structure remote from the heating elements. Thus, heat is transmitted by convection to parts of the frame structure separated from the directly heated parts by rubber seals or gaskets 50 which do not conduct heat as readily as does the metal of the frame structure. It has been found that the heating elements can be confined to the lower two thirds of a frame structure without impairing the effectiveness of the heating 55 elements to reduce condensation on the frame structure.

In use, energisation of the heating elements 38 or of the heating elements 43 is controlled by a thermostatic switch (not shown) arranged to 60 sense the temperature at a position which may be outside the building or may be on or in the frame structure 11. The control means may be arranged to energise the heating elements continuously whilst the outside temperature is below a 65 predetermined value. Alternatively, the control means may be arranged to energise the heating elements intermittently in a manner to prevent the temperature of the frame structure falling below a predetermined value. A thermostatic switch 70 mounted on or in the frame structure is preferably situated at the coldest part of the frame structure.

The heating elements are preferably supplied from a low voltage source of electric current, conveniently a transformer connected to the 75 mains supply.

In a further modification of the window shown in Figure 1, heating elements similar to the elements 43 are disposed in an elongated cavity defined between the timber surround 10 and the 80 frame structure 11. A single heating tape may extend around the entire periphery of the frame structure.

Claims

1. A method of reducing the condensation of 85 water vapour on a window frame structure wherein an electrically energisable heating element is applied to the structure and an electric current is passed through the heating element intermittently.

90 2. A method according to Claim 1 wherein energisation of the heating element is controlled in accordance with the temperature at a position outside the window or in accordance with the temperature at a position on or within the frame 95 structure.

3. A method according to Claim 1 or Claim 2 wherein the heating element is energised sufficiently to avoid the temperature at a position on or within the frame structure falling below a

100 predetermined value.

4. A method according to any preceding claim wherein a fraction only of the frame structure has applied thereto a heating element.

5. A method according to Claim 4 wherein less

105 than one third of the frame structure has applied thereto a heating element.

6. A method according to any preceding claim wherein heat is transmitted by conduction from the heating element through a wall of the frame

110 structure to air contained in an elongated substantially closed space defined by the frame structure, either alone or in conjunction with other components of the window, and the heat is transmitted by convection of the air to a further

115 part of said wall and/or to a further wall of the frame structure.

7. A window comprising a frame structure and one or more glazing panels supported by the frame structure, wherein there is mounted on or in

120 the frame structure an electrically energisable heating element.

8. A window according to Claim 7 wherein the heating element or each heating element is mounted on or in a lower part only of the frame

125 structure.

9. A window according to Claim 7 or Claim 8 wherein there is provided on or in not more than one half of the frame structure a plurality of heating elements.

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10. A window according to any one of Claims 7 to 9 wherein the or each heating element is engaged with a part of the frame structure to transmit heat thereto by conduction.

5 11. A window according to Claim 10 wherein the frame structure defines glazing channels in which respective marginal portions of the glazing panel or panels are received and wherein the heating elements or each of same is disposed in a 10 glazing channel.

12. A window according to Claim 11 wherein a mouth of the glazing channel is closed to provide a substantially closed airspace within and extending along substantially the entire length of

15 the glazing channel.

13. A window according to any one of Claim 7 to 12 wherein the frame structure is formed of or formed mainly of metal.

14. A window according to Claim 7 wherein the 20 frame structure is hollow and defines, either alone or in conjunction with glazing panels and glazing gaskets or in conjunction with a masonry wall or a timber frame, elongated air spaces which are substantially closed in use of the window. 25 15. A window according to any one of Claims 7 to 14 comprising a movable glazing panel which is supported by an associated movable part of the frame structure, wherein a heating element is mounted on or in said part of the frame structure 30 and there are provided on said part two connector elements of respective two-element separable connectors, other elements of which are arranged to establish electrical contact with the connector elements on said parts of the frame structure 35 when the movable panel is in a closed position.

16. For use in a method according to Claim 1, a heating device comprising a hollow housing, an electrically energisable heating element disposed within the housing, a further electrical conductor 40 disposed within the housing, first and second parts of a two-part electrical connector mounted at spaced positions in the housing and each having a first connector element connected with the heating element and a second connector 45 element connected with the further conductor, the connector parts being so arranged that the first part can co-operate with the second connector part of an identical device and the second part can co-operate with the first connector part of a 50 further identical device and the second part can co-operate with the first connector part of a further identical device to connect the heating elements of the three devices electrically in series with one another and to connect the further 55 conductors of the three devices electrically in series with one another.

17. A device according to Claim 16 wherein the housing has a substantially flat external surface and the heating element is adjacent to said

60 surface at the inside of the housing.

18. A device according to Claim 17 comprising a plate on which said surface is formed.

19. A device according to Claim 18 further comprising a structurally separate cover mounted

65 on the plate.

20. A heating device substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawing.

70 21. A window having heating elements arranged substantially as herein described with reference to and as illustrated in Figure 3 of the accompanying drawings.

22. Any novel feature or novel combination of 75 features disclosed herein or in the accompanying drawing.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Pubtished by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obttirwd.