Abstract: Crankcase heater including heat-generating electrical resistance elements and the method of manufacturing such heaters. The resistance elements include at least one positive temperature coefficient (PTC) heater element, platelet in form, adhesively bonded between a pair of metallic conductor-electrodes using an electrically conductive adhesive of high thermal conductivity. The electrodes formed for integral connection to electrically conductive lead wires serve as heat sinks dimensioned in length to provide a heater of predetermined wattage. The assembly of resistance elements, electrodes and lead wire connections are molded within the sheath of electrical insulation which is a silicone elastomer, having ceramic particles dispersed therein for enhanced thermal conductivity. The insulated heater is dimensioned in cross section so that when disposed within the well of a crankcase (compressor) its outer surface will leave a clearance which is less than thermal expansion of the silicone elastomer.

Abstract: An electrical resistance heater includes a pliable thermally insulative base grooved in a major surface thereof and a flexible electrical resistance heating wire fitted within the groove. The heating wire insulated throughout its length is elastically gripped by the base and the outer surface portion of the heating wire throughout its length extends outwardly of the major surface of the base, providing a unidirectional heat source for use as a "spot heater". Connections of the heating wire to lead wires are disposed within two preformed cavities provided in the major surface of the base. The cavities open in the same direction as the groove and a suitable moisture impervious insulating material disposed within the cavities seals the connections.