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An electric heater is described. The heater is composed of a plastic
or a rubber strip conductor with a heat resistant and electric conductive
chemical dispersed therethrough and electric conductors disposed
on either side of the strip conductor so that when the electric
conductors are coupled to a source of electrical energy current
will flow through the strip and generate heat. The strip conductor
then is covered with a polyethylene layer which is adhered thereto,
and the polyethylene layer in turn is covered by a PVC layer.
An electric heater employs plate-shaped heating elements, each
consisting of a core of semiconductor material whose opposing faces
are coated with conductive material and having a multiplicity of
apertures to permit passage of air. The heater includes a housing
with a rear air inlet and a forward air outlet. A fan having a fan
venturi causes air flows forwardly through the housing. A two-piece,
ceramic holder maintains a number of the plate-shaped heating elements
in generally coplanar, spaced-apart relationship, in front of a
forward venturi opening. The holder has a large recess positioned
over the forward venturi opening which receives substantially all
air flow from the venturi, and a number of passages, one associated
with each heating element, which direct air from the recess through
the cores towards the forward air outlet. Each of the passages flares
radially outwardly and rearwardly from the rear face of the associated
heating element, and opens into the recess and the recess flares
radially outwardly and rearwardly from about the passage openings
to the forward venturi opening. The arrangement results in improved
heat transfer and much quieter operation than would otherwise be
achieved. To accommodate thermal expansion and contraction of the
heating elements, the two pieces of the holder are clamped together
by spring-loaded bolts which permit the spacing between the holder
members to vary, while still securing the heating elements.
An electric heater incorporating simple support structure therefor.
A frame is insulated from an electric resistance heater coil by
insulator supports mounted within beam members of the frame. The
supports incorporate structural features enabling the use of simplified
supporting beams. The support insulators include additional structural
features for retaining the resistance wire in place and for simplified
engagement therewith. The insulators may project on both sides of
the support beams and retain heater wires in two planes. The support
insulators further provide an integrated structure easily fabricated
and simply assembled to the frame.
An insulator for an electric heater employs a central elongated
slot and two guide surfaces. Below each guide surface is a notch
for receiving an outer convolution of a heater coil, while the central
slot terminates in a notch for receiving an intermediate convolution
of the heater coil. The slot engages the central convolution of
the heater coil before outer convolutions engage the guide surfaces
to facilitate installation of the insulator. As the insulator is
inserted into the heater coil, the guide surfaces engage the outer
convolutions and direct them to respective notches for securely
holding the heater coil. The insulator may support a single pass
of the heater coil or may be arranged to have these surfaces and
notches on opposite ends to support two passes of the heater coil.
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