A medical device having a heater with at least one heating element which has mains voltage applied to it by a heating control unit. The heating control unit includes a monitoring arrangement and a switching arrangement. The monitoring arrangement can recognize the zero crossings of the mains voltage, and the switching arrangement can switch the at least one heating element on or off in the zero crossing. The heating control unit controls the power of the heating by switching on and off of one or more half cycles of the mains AC voltage.