Patent ID: 8344896

Claim:
A process for detecting scale deposits in a liquid supply means of a machine comprising at least a water tank, a pump and a heating means, comprising the step of pumping water from the water tank to the heating means, and energizing the pump by a controller by providing the pump with an energizing signal to produce an intended water flow rate F, measuring an actual water flow rate f and comparing a discrepancy Δ between the actual water flow rate f and the intended water flow rate F to an operating instruction related to scale deposit; wherein the pump is a solenoid pump comprising a spring-loaded linear pumping member axially displaceable between a spring-loaded position and a spring-released end position controlled by the controller responsive to a current waveform, and arranging to generate an energizing signal for controlling the pumping member from the current waveform by excluding a part of the current waveform from the energizing signal such that the pumping member is energized into an intermediate position between the spring-released end position and the spring-loaded position.