Importance

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Abstract

Apparatus for electrically heating a fluid medium includes a housing (18) having an inlet channel (54) and an outlet channel (60) communicating with a central passage (62). A heating cartridge (38) is resident in the central passage (62) and has a web (90) defining first and second series connected interior channels in communication respectively with the inlet and outlet channels (54, 60). A continuous electric resistance heating coil (94) extends successively through the interior channels and includes a mechanically stressed portion (94a) bridging the first and second interior channels. The bridging portion (94a) is electrically shunted by an electrically conductive member (96) to eliminate current flow therethrough to lessen the likelihood of burnout or failure of the stressed portion (94a). The heating coil (94) is controlled by temperature controller (22) having a temperature sensor (20) in the central passage (62) in juxtoposition with the shunted coil portion (94a) to reduce or eliminate the effects of heating coil radiant energy on the temperature sensor (20). The switching unit (28) of the temperature controller (22) is supported on the housing (18) in communication with the fluid inlet channel (54) to prevent overheating of the switching unit.

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First Claim