Patent ID: 8692167

Claim:
A medical device comprising a heater having two heating elements, and a heating control unit, which is configured to be connected to mains AC voltage, connected to the heater, the heating control unit comprising a monitoring arrangement configured to recognize zero crossings of the mains AC voltage and a switching arrangement configured to switch the at least one heating element on or off in the zero crossing, wherein the monitoring arrangement is configured to detect a level of the mains AC voltage, the heating control unit is configured to control power of the heater by switching on and off one or more half cycles of the mains AC voltage, and control the two heating elements based on a detected level of the mains AC voltage so as to operate in parallel in a first operating mode for a detected level of the mains AC voltage in a first voltage range between 80 V and 160 V, and operate in parallel in a second operating mode that is different from the first operating mode for a detected level of the mains AC voltage in a second voltage range between 180 V and 250 V.