Abstract: A purification device for purifying dirty liquid is provided. The device includes a heating vessel for heating the dirty liquid, at least one inlet valve, at least one outlet valve, at least one gas overpressure valve for discharging gas located in the heating chamber, the valves being mechanically engaged with each other via a valve control unit such that in operation of the heating vessel, up to a limit gas pressure, the inlet valve can be operated in an open position and the outlet valve and the gas overpressure valve can be operated in a closed position), and once the limit gas pressure has been exceeded, the inlet valve can be closed by the valve control unit and the outlet valve and/or the gas overpressure valve can be opened by the valve control unit.