WO2009107118A2

WO2009107118A2 - A panel heater

Info

Publication number: WO2009107118A2
Application number: PCT/IE2009/000004
Authority: WO
Inventors: Song LUAN; Wen Yan Luan; Zhu LUAN
Original assignee: Bclap Holdings Limited
Priority date: 2008-02-25
Filing date: 2009-02-25
Publication date: 2009-09-03
Also published as: CN201178494Y

Abstract

A heating panel (1) comprises an electrical circuit (2), an electrical connector (3, 4) at each end of the electrical circuit, and a resistive foil heating unit (5) sandwiched between a pair of thin-film insulating layers (6). The resistive foil heating unit (5) comprises positive and negative electrically conductive contact strips (8, 9) extending along opposite edges and connected by one or more resistive foil conductors (10). The resistive foil heating unit (5) is electrically connected in parallel to the circuit (2), the circuit ideally including a positive bus (19a) adapted to provide electrical connection between positive terminals (15, 17) of the electrical connectors, and a negative bus (19b) adapted to provide electrical connection between negative terminals (16, 18) of the electrical connectors. The panel comprises a protective cover (13) that encloses the resistive foil heating unit (5) and the circuit (2), wherein the electrical connectors (3, 4) typically exposed outside of the insulating cover.

Description

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Technical Field

This invention is related to a heating panel of the type having a resistive heating foil embedded between thin-film insulating layers.

Background to the Invention

Currently, metallic electrical heating films are been widely used in underfloor heating, generally by burying metallic electrical heating films (underfloor heating panel) under a cement ground. Existing underfloor heating panels include two thin-film insulating layers, one on top and one on bottom, and a metallic resistance foil disposed between these two layers. The ends of the metallic thin film wires are connected to the positive and the negative power supply, respectively. In construction, heating panels are either connected in series, which entails that the resistive heating units must carry all of the current being supplied to the series of heaters, or in parallel using several sublines of the two main buses, where the sub-lines are normally located and connected externally of the heating panels through connecting terminal plug-ins and sealed by using heatshrink tubing with glue, to avoid water leakage.

There are several problems in current underfloor heating panel structure. First, here is only one layer of insulating thin film each on top and bottom of the metallic thin film wire. During construction, it is easily damaged due to stray or protruding sand or gravel; in addition, as the cement layer is adjacent to the ground, any damage will affect a large area of the heating element. This also sometimes causes malfunction of the circuit breakers. Secondly, the buses between underfloor heating panels are externally connected, namely, they are on the outside of the insulating thin film. In this configuration, the bus cable is very long, which means connection becomes difficult and messy, especially beneath the cement layer, which means that the construction procedure becomes even more complicated.

It is an object of the invention to overcome at least one of the above-referenced problems. Statements of Invention

According to the invention, there is provided a heating panel comprising an electrical circuit, an electrical connector at each end of the electrical circuit, and a resistive foil heating unit sandwiched between a pair of thin-film insulating layers. The resistive foil heating unit comprises positive and negative electrically conductive contact strips extending along opposite edges and connected by one or more resistive foil conductors. The resistive foil heating unit is electrically connected in parallel to the circuit, the circuit ideally including a positive bus adapted to provide electrical connection between positive terminals of the electrical connectors, and a negative bus adapted to provide electrical connection between negative terminals of the electrical connectors. The panel comprises a protective cover that encloses the resistive foil heating unit and the circuit, wherein the electrical connectors typically exposed outside of the insulating cover.

The provision of the resistive foil heating unit that is electrically connected in parallel to the circuit, and the positive and negative bus connectors, enables a large proportion of the current in the circuit to by-pass the resistive heating unit and pass along the main electrical bus. Thus, by lowering the amount of current required to pass through the resistive foil, the lifetime of the foil is extended. Additionally, in embodiments where the panel comprises more than one resistive heating unit (for example where there are two, three or four resistive heating units all connected in parallel along the circuit), the number of resistive heating units that can be connected to the circuit is not determined by the current rating of the foil in the resistive heating unit (which would be the case if the electrically conductive contact strips were connected in series along the circuit) . The panel heater of the invention also importantly obviates the need to complete the electrical circuit externally of the panel heater, and therefore removes the risk that conditions external of the heater, for example rain or physical damage or, in the case of underfloor heaters, cement and gravel and moisture, water and the like, damage the electrical circuit.

Typically, the foil electrically conductive contact strips forming part of heating unit have a thickness of from 5 to 10 microns. This thickness of foil provides a maximum current rating of from 4 to 7 amps. Thus, as indicated above, the invention allows the current carrying capacity of the foil in the resistive heating layer to be quite low.

The electrical circuit ideally comprises a positive bus adapted to provide electrical connection between the positive terminals of the electrical connectors, and a negative bus adapted to provide electrical connection between the negative terminals of the electrical connectors.

Typically, the positive and negative bus connectors each have a maximum current rating of at least 6 amps, preferably from 6 to 25 amps, depending on their construction.

Generally, the bus connectors are copper or aluminium wires, as opposed to thin film foil conductors. This allows the bus connectors have a higher current carrying capacity.

Ideally, the positive bus and negative bus are located between the pair of thin-film insulating layers. Generally, the thin film layers are formed of PET. Each thin film layer generally has a thickness of from 50 to 150 microns. Suitably, the outer cover is formed of a polymer fibre material such as Nylon or PET, which may also be impregnated with a material such as polyurethane to improve its electrical insulation and waterproofing properties. In one embodiment, the resistive foil heating unit is mounted on a supporting layer. Suitably, the supporting layer is formed of a PET polymer.

In a preferred embodiment of the invention, one of the electrical connectors comprises an electrical plug, and the other electrical connector comprises an electrical socket, wherein the plug of one panel is adapted for electrical connection with a socket of an adjacent panel, and vica versa. In this manner, the panels may be connected together in series, and may be employed as components of a modular panel heating system. In this regard, for example, a plug of a first panel connects to a power supply socket, and then the socket of the first connector is 'electrically connected to a plug of a second panel, etc. ^' The final panel only includes a plug (and no socket) for connection to a socket of the penultimate panel in the series.

In one embodiment of the invention, a single panel comprises at least two resistive foil heating units, each resistive foil heating unit being connected in parallel along the circuit and being enclosed within the protective cover. An example of this arrangement is illustrated in Figs. 3 and 4.

Suitably, the protective cover is electrically insulating. Ideally, the protective cover is waterproof. Accordingly, the invention also provides a modular system for heating a space and comprising a plurality of heating panels according to the invention adapted to be physically connected together in series while the resistive heating units are electrically connected in parallel to each other.

In one embodiment, the modular heating system comprises:

- a first heating panel comprising a heating panel according to the invention, a first connector of the first heating panel adapted for connection to a power supply and a second connector of then first heating panel adapted for electrical connection to an adjacent heating panel;

a final heating panel comprising a heating panel according to the invention and optionally having a single electrical connector; and

optionally, one or more intermediate heating panels, each comprising a heating panel according to the invention, connected in series between the first and final heating panels.

Typically, the modular heating system comprises from one to ten intermediate heating panels.

The invention also relates to a use of a heating panel according to the invention, or a modular system according to the invention, as an underfloor heater or as a mounted poster-type heater.

Brief Description of the Figures

Fig 1 is a diagram of a panel heater of the invention;

Fig 2 is an illustration of a modular heating system comprising a plurality of panel heaters of Fig. 1;

Fig. 3 is a diagram of a panel heater according to an alternative embodiment of the invention in which the panel comprises two resistive foil heating layers; and

Fig. 4 is a diagram of the panel heater of Fig. 3 in which the electrical connectors are arranged in a different orientation.

Detailed Description of the Invention

Referring to the drawings, and initially to Fig. 1, there is illustrated a panel heater according to the invention, indicated generally by the reference numeral 1, and comprising an electrical circuit 2, an electrical connector

3, 4 at each end of the electrical circuit 2, and a resistive foil heating unit 5 sandwiched between a pair of thin-film insulating layers 6. The resistive foil heating unit 5 comprises positive and negative electrically conductive contact strips 8, 9 extending along opposite edges and connected by one or more resistive foil conductors 10 connected in parallel. The resistive foil heating unit is connected to the circuit, and the panel 1 comprises a protective cover 13 that encloses the resistive foil heating unit 5 and the circuit 2. The electrical connectors 3, 4 are exposed outside of the protective cover 13.

In more detail, the electrical connector 3 is a plug and comprises a positive terminal 15 and a negative terminal 16, and the electrical connector 4 is a socket and comprises a positive terminal 17 and a negative terminal 18. The positive terminal 15 (of the plug 3) is electrically connected to the positive electrically conductive contact strip 8, and the positive terminal 17 of the electrical connector (socket) 4 by a positive electrical bus 19a. The negative terminal 18 (of the socket 4) is electrically connected to the negative contact strip 8, and to the negative terminal 16 (of the plug 3) by a negative electrical bus 19b.

In use, and referring to Fig, 2, a plurality of the panel heaters 1 are connected in series by means of the plugs 3 and sockets 4 via a heat controller 25. However, even though the panel heaters are connected in series, the resistive heating units are electrically connected in parallel, thereby ensuring that only a portion of the total current in the circuit passes through each of the heating units. As indicated above, this allows a resistive foil with a low current rating to be used in the heating units, thereby minimising current loss and prolonging the life of the resistive heating circuits. Referring to Figs 3 and 4, an alternative embodiment of panel heater is described, in which parts similar to those described with reference to Figs 1 and 2 are assigned the same reference numerals. Referring initially to Fig. 3, the panel heater 20 comprises two resistive foil heating units 21, 22 mounted in parallel along the single electrical circuit 2. In the example shown, the electrical connectors 3, 4 are located externally of the protective cover 13 on opposite sides of the end of the heater 20. Referring to Fig. 4, the panel heater is identical to that described with reference to Fig. 3 except that the connectors 3, 4 are located at the sides of the panel heater. The operation of these two embodiments of the panel heater are identical to that described with reference to Fig. 1.

The invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail without departing from the spirit of the invention.

Claims

l.A heating panel (1) comprising an electrical circuit (2), an electrical connector (3, 4) at each end of the electrical circuit, and a resistive foil heating unit (5) sandwiched between a pair of thin-film insulating layers (6), the resistive heating unit (5) having positive and negative electrically conductive contact strips (8, 9) extending along opposite edges and connected by one or more resistive foil conductors (10), the resistive foil heating unit being connected in parallel to the circuit, the circuit (2) including a positive bus (19a) adapted to provide electrical connection between positive terminals (15, 17) of the respective electrical connectors, and a negative bus (19b) adapted to provide electrical connection between negative terminals (16, 18) of the respective electrical connectors, wherein the panel comprises a protective cover (13) that encloses the resistive foil heating layer (5) and the circuit (2), and wherein the electrical connectors (3, 4) are exposed outside of the protective cover.

2. A heating panel as claimed in Claim 1 in which the electrically conductive contact strips (8, 9) forming part of the resistive foil heating unit have a thickness of from 5 to 10 microns.

3. A heating panel as claimed in Claim 1 or 2 in which the positive and negative bus connectors (19a, 19b) each have a maximum current rating of at least 6 amps.

4. A heating panel as claimed in any preceding Claim in which the positive bus and negative bus connectors

(19a, 19b) are located between the pair of thin-film insulating layers (6).

5. A heating panel as claimed in any preceding Claim in which the one of the electrical connectors comprises an electrical plug (3), and the other electrical connector comprises an electrical socket (4), wherein the plug (3) of one panel (1) is adapted for electrical connection with a socket (4) of an adjacent panel (1) .

6. A heating panel as claimed in any preceding Claim and comprising at least two resistive foil heating units (5), each resistive foil heating unit being connected in parallel with the circuit (2) and being enclosed within the protective cover (13) .

7. A heating panel as claimed in any preceding Claim in which the protective cover (13) is electrically insulating.

8. A heating panel as claimed in any preceding Claim in which the protective cover (13) is waterproof.

9. A modular system for heating a space and comprising a plurality of heating panels (1) according to any of Claims 1 to 8 adapted to be connected together in series .

10. A modular system as claimed in Claim 9 and comprising: a first heating panel (1) comprising a heating panel according to any of Claims 1 to 8, a first connector (3) of the first heating panel (1) adapted for connection to a power supply and a second connector (4) of the first heating panel adapted for electrical connection to an adjacent heating panel (1) ;

- a final heating panel (I)' comprising a heating panel according to any of Claims 1 to 8 and which, optionally, has only a single electrical connector adapted for electrical connection with a preceding heating panel; and

optionally, one or more intermediate heating panels according to any of Claims 1 to 8 connected in series between the first and final heating panels.

11. A modular system as claimed in 10 comprising between one and ten intermediate heating panels (1) .

12. Use of a heating panel according to any of Claims 1 to 8, or a modular system according to any of Claims

9 to 11, as an underfloor heater.

13. Use of a heating panel according to any of Claims 1 to 8, or a modular system according to any of Claims 9 to 11, as a wall mounted poster-type heater.