Device for preventing overheating of electric apparatuses

An apparatus for preventing overheating of electric heaters wherein said heater includes a casing having a front wall, a rear wall and side walls, a terminal block enclosed in said casing and a number of electric heating elements connected to and supported by said terminal block inside said casing, upper and lower apertures provided in said casing to define an air passage therethrough, said apparatus comprising:

• an aperture formed in said casing at a position between said upper and lower openings;
• an air channel arranged external to said casing between said upper and lower openings comprising a vertically disposed tube including an intermediate tube perpendicular to said vertically disposed tube, said intermediate tube forming a communication between said vertically disposed tube and said aperture for allowing said air channel to communicate via said aperture with said air passage of said casing;
• a sensing body, arranged in said air channel at a position above said aperture, operatively connected to a switch means for controlling a power supply to said heating elements;
• and
• a flow duct, provided in said casing immediately below said aperture, for preventing, during normal operation of the electric apparatus, heated air from the interior of said casing from reaching said sensing body in said air channel through said aperture, said aperture and said flow duct being formed by a longitudinal slot in one wall of said casing, said aperture allowing heated air to flow over said sensing body in the event said upper opening is obstructed.