Abstract: An arrangement for preventing overheating in electric air heaters of the type having a plurality of electric heating elements disposed in a casing defining a vertical air flow path having a lower air inlet and an upper air outlet includes the placement of a temperature sensing device in a vertical air channel located adjacent and external to the casing. The vertical air flow channel communicates with the vertical air flow path intermediate the inlet and outlet via an aperture in the casing wall. A flow duct is provided in the casing below the aperture for preventing, during normal operation of the heater, heated air from the interior of the casing from reaching the sensing device in the air channel. If the outlet of the flow path is obstructed, a portion of the hot air well travel from the casing through the aperture to the sensing device to activate the sensing device to deenergize the heating elements.

Abstract: A circuit for connecting to an alternating current electric network having at least one phase a high-power electric heating device, such as a sauna heater, provided with a plurality of electric heating elements. Each phase of the network is evenly divided into a number of separate part leads such that the total number of part leads are arranged in two equal series. A first switch is arranged to simultaneously open and close all of the part leads of both series. A second multipolar switch controlled by a thermostat is adapted to open at least one of the separate part leads of one of the series. Each heating element is connected in circuit with one part lead from each series of part leads. The network may be three phase with the heating elements being delta-connected.