Radiant electric heater

1. A radiant electric heater comprising at least first and second adjacent heating zones, the first heating zone including a first heating element portion and the second heating zone including a second heating element portion, and terminal means provided at a periphery of the heater for connecting the first and second heating element portions to a source of electrical energy and including first, second and third electrical connectors, the third electrical connector being positioned intermediate the first and second electrical connectors and a radially inner region of each of the first and second electrical connectors extending generally circumferentially of the heater in a direction away from the terminal block, wherein the heating element portions are integral with conjoined ends connected to the first electrical connector, with one free end connected to the second electrical connector, and with another free end connected to the third electrical connector, the first, second and third electrical connectors including means for connecting to the heating element portions in such a way that the heating element portions are not deflected from their intended path to any substantial extent.

2. A heater as claimed in claim 1 , wherein the radially inner region of the first electrical connector extends substantially at 80 degrees to a portion thereof passing through the terminal block.

3. A heater as claimed in claim 1 , wherein the radially inner portion of the second electrical connector extends substantially at 45 degrees to a portion thereof passing through the terminal block.

4. A heater as claimed in claim 1 , wherein a radially inner region of the third electrical connector extends generally circumferentially of the heater in a direction towards one of the first and second electrical connectors.

5. A heater as claimed in claim 4 , wherein the radially inner portion of the third electrical connector includes a link element which passes across the region of the conjoined ends of the first and second heating element portions.

6. A heater as claimed in claim 5 , wherein the link element passes over the region of the conjoined ends of the first and second heating element portions.

7. A heater as claimed in claim 6 , wherein the link element passes under the region of the conjoined ends of the first and second heating element portions.

8. A heater as claimed in claim 4 , wherein the radially inner portion of the second electrical connector extends substantially at 45 degrees to a portion thereof passing through the terminal block.

9. A heater as claimed in claim 1 , wherein a radially inner region of the second electrical connector extends generally circumferentially of the heater in a direction away from the terminal block.

10. A heater as claimed in claim 9 , wherein the radially inner portion of the second electrical connector extends substantially at 45 degrees to a portion thereof passing through the terminal block.

11. A heater as claimed in claim 9 , wherein the radially inner portion of the third electrical connector includes a link element which passes across the second heating element portion.

12. A heater as claimed in claim 9 , wherein the radially inner portion of the first electrical connector includes a link element which passes across the second heating element portion.

13. A radiant electric heater comprising at least first and second adjacent heating zones, the first heating zone including a first heating element portion and the second heating zone including two second heating element portions electrically connected in parallel, the first and second heating element portions forming a heating element in the form of a double spiral, a first strand of the double spiral extending from a peripheral region of the heater to a central region thereof and a second strand of the double spiral extending from a central region to the peripheral region thereof, terminal means provided at a periphery of the heater for connecting the first and second heating element portions to a source of electrical energy, and wherein the heating element portions are integral with conjoined ends connected to a first electrical connector, with one free end connected to a second electrical connector, and with another free end connected to a third electrical connector, the first, second and third electrical connectors including means for connecting to the heating element portions in such a way that the heating element portions are not deflected from their intended path to any substantial extent, and wherein a conducting link is provided between the first electrical connector and the first and second strands of the double spiral in the region of a junction between the first and second heating zones.

14. A heater as claimed in claim 13 , wherein a further conducting link is provided between the third electrical connector and the first strand of the double spiral in the region of the junction between the first and second heating zones.

15. A heater as claimed in claim 14 , wherein the first strand is severed between the first-mentioned and further conduction links.

16. A radiant electric heater comprising at least first and second adjacent heating zones, the first heating zone including a first heating element portion and the second heating zone including a second heating element portion, and terminal means provided at a periphery of the heater for connecting the first and second heating element portions to a source of electrical energy and including first, second and third electrical connectors, the third electrical connector being positioned intermediate the first and second electrical connectors and a radially inner region of each of the second and third electrical connectors extending generally circumferentially of the heater in a direction away from the terminal block, wherein the heating element portions are integral with conjoined ends connected to the first electrical connector, with one free end connected to the second electrical connector, and with another free end connected to the third electrical connector, the first, second and third electrical connectors including means for connecting to the heating element portions in such a way that the heating element portions are not deflected from their intended path to any substantial extent.

17. A heater as claimed in claim 16 , wherein the radially inner portion of the second electrical connector extends substantially at 45 degrees to a portion thereof passing through the terminal block.

18. A heater as claimed in claim 16 , wherein the radially inner portion of the third electrical connector extends substantially at 45 degrees to a portion thereof passing through the terminal block.

19. A heater as claimed in claim 16 , wherein a radially inner region of the first electrical connector extends generally circumferentially of the heater in a direction towards one of the second and third electrical connectors.

20. A heater as claimed in claim 19 , wherein the radially inner region of the first electrical connector extends substantially at 80 degrees to a portion thereof passing through the terminal block.

21. A radiant electric heater having a circumference and comprising at least first and second adjacent heating zones, the first heating zone including a first heating element portion and the second heating zone including a second heating element portion, and terminal means provided at a periphery of the heater for connecting the first and second heating element portions to a source of electrical energy, wherein the heating element portions are integrally formed from a continuous heating element with conjoined ends connected to a first electrical connector, with one free end connected to a second electrical connector, and with another free end connected to a third electrical connector, the first, second and third electrical connectors including means for connecting to the heating element portions in such a way that the heating element portions extend generally circumferentially of the heater in the region of connection and are not deflected from their intended path to any substantial extent, the third electrical connector being positioned intermediate the first and second electrical connectors and a radially inner region of each of the first and second electrical connectors extending generally circumferentially of the heater in a direction away from the terminal block.

22. A radiant electric heater having a circumference and comprising at least first and second adjacent heating zones, the first heating zone including a first heating element portion and the second heating zone including a second heating element portion, and terminal means provided at a periphery of the heater for connecting the first and second heating element portions to a source of electrical energy, wherein the heating element portions are integrally formed from a continuous heating element with conjoined ends connected to a first electrical connector, with one free end connected to a second electrical connector, and with another free end connected to a third electrical connector, the first, second and third electrical connectors including means for connecting to the heating element portions in such a way that the heating element portions extend generally circumferentially of the heater in the region of connection and are not deflected from their intended path to any substantial extent, the arrangement being such that the heating element portions form a heating element in the form of a double spiral, a first strand of the double spiral extending from a peripheral region of the heater to a central region thereof and a second strand of the double spiral extending from a central region to the peripheral region thereof, the second heating element being formed in two element portions which are electrically connected in parallel, a conducting link being provided between the first electrical conductor and the first and second strands of the double spiral in the region of the junction between the first and second heating zones.

23. A radiant electric heater having a circumference and comprising at least first and second adjacent heating zones, the first heating zone including a first heating element portion and the second heating zone including a second heating element portion, and terminal means provided at a periphery of the heater for connecting the first and second heating element portions to a source of electrical energy, wherein the heating element portions are integrally formed from a continuous heating element with conjoined ends connected to a first electrical connector, with one free end connected to a second electrical connector, and with another free end connected to a third electrical connector, the first, second and third electrical connectors including means for connecting to the heating element portions in such a way that the heating element portions extend generally circumferentially of the heater in the region of connection and are not deflected from their intended path to any substantial extent, the first electrical connector being positioned intermediate the second and third electrical connectors and a radially inner region of each of the second and third electrical connectors extending generally circumferentially of the heater in a direction away from the terminal block.