A control unit (5) measures the power consumed by a PTC element (3), and compares the measured power to a specified power threshold value, Plim, which is smaller than a minimum heat output, Pmin. The control unit recognizes the interruption of air current ...

The electric heater has several heating elements assembled to form a heating block mounted in a rectangular frame and a controller forming a unit with the heating block and with power transistors (11) on a circuit board (10) for setting the currents to the...

The heater has heating elements (2) in a block in a rectangular frame (3-5) and a controller forming a unit with the block. The heating power of the heating elements can be adjusted via the current flowing through them and the controller contains power tra...