|
A radiant electric heater has first, second and third heating zones
(1, 2, 3) arranged substantially side-by-side. The first heating
zone (1) is provided with at least one first heating element (9).
The second heating zone (2) is arranged adjacent to the first heating
zone and is provided with at least one second heating element (10).
The third heating zone (3) is arranged adjacent to the second heating
zone and is provided with at least one third and one fourth heating
element (11, 12). A switch (15) is provided for switching between
first, second and third heating states. In the first heating state
the at least one first heating element (9) of the first heating
zone (1) is energised alone, the at least one second, third and
fourth heating elements (10, 11, 12) of the second and third heating
zones (2, 3) being de-energised. In the second heating state the
at least one first heating element (9) of the first heating zone
(1) is electrically connected and energised in parallel with the
at least one second heating element (10) of the second heating zone
(2), the at least one third and fourth heating elements (11, 12)
of the third heating zone (3) being de-energised.
A radiant electric heater includes a base (2) of thermal and electrical
insulation material having a surface supporting at least one heating
element (3) in the form of an elongate electrically conductive ribbon
(4). The ribbon (4) is supported on edge and is partially embedded
in the surface of the base (2). A rod-like temperature-responsive
device (7, 8) extends at least partly across the heater from an
edge of the heater and over the at least one heating element (3).
The surface of the base (2) is provided with a shallow recess (9)
beneath the rod-like temperature-responsive device (7, 8) and the
ribbon (4) is partially embedded in the shallow recess (9) to a
lesser extent than in the surface of the base (2) at either side
of the shallow recess.
A base for an electric heater comprises a base layer (13) of compacted
insulation material (12) and a substantially U-shaped electrically
conductive link (6) having upstanding leg portions (8, 9) with an
elongate portion (7) extending therebetween. The link is embedded
in the base layer with the leg portions protruding therefrom. The
base layer (13) incorporates at least one recess (14) extending
from a surface thereof to the elongate portion (7) of the link
A novel radiant electric heater construction is provided employing
fused silica particulates as the thermal and electrical insulation
medium in said device. Said insulation means is prepared in a particular
manner providing a porous characteristic when employed together
with operatively associated metal heat shield means in the heater
device. |