a liquid flow through heater for heating a liquid comprises a channel and an electric heater element for heating at least a portion of the channel . a temperature sense unit senses a temperature indicative of the temperature of the liquid . a flow control means controls a flow of the liquid through the channel . a controller controls in a first phase , the electric heater element to pre - heat at least the portion of the channel , and the flow control means to obtain a rate of flow of the liquid through the channel which is zero or relatively small with respect to a rate of flow during a second and / or third phase . the controller controls in the second phase succeeding the first phase , the electric heater element to supply a predetermined heating power independent on the sensed temperature , and the flow control means to obtain a flow of the liquid through the channel , and in the third phase succeeding the second phase , the electric heater element to supply a heating power in dependence on the sensed temperature to substantially stabilize the sensed temperature on a desired target value , and the flow control means to obtain a flow of the liquid through the channel .