Heating device, in particular cooling water heating mechanism for diesel motor vehicles, as well as heating system, heating unit, and power unit therefor

The heating device has several heating elements, the loads of two of which are equal. One of these is controlled by an adjustable semiconductor element. This element has a switch enabling it to be switched to one of the other heating elements. The control switch enables binary pre-setting of the heating load. Fine setting is provided by the adjustable semiconductor element. The device includes a heater (10), a regulating module (20) and a load module (30).