A liquid flow through heater for heating a liquid (10) comprises a channel (4) and an electric heater element (50) for heating at least a portion of the channel (4). A temperature sense unit (6, 60) senses a temperature (ST1; ST1, ST2) indicative of the temperature of the liquid. A flow control means (3) controls a flow of the liquid (10) through the channel (4). A controller (7) controls in a first phase (PH1), (i)the electric heater element (50) to pre-heat at least the portion of the channel (4), and (ii) the flow control means (3) to obtain a rate of flow ofthe liquid (10 through the channel (4) which is zero or relatively small withrespect to a rate of flowduring a second and/or third phase. The controller (7) controls in thesecond phase (PH2) succeeding the first phase (PH1), (i) the electric heater element (50) to supplya predetermined heating power independent on the sensed temperature (ST1; ST1, ST2),and (ii) the flow control means (3) to obtain a flow of the liquid (10) through the channel (4), and in thethird phase (PH3) succeeding the second phase (PH2), (i) the electric heater element (50) to supply a heating power (HP) in dependence on the sensed temperature (ST1; ST1, ST2) to substantially stabilize the sensed temperature (ST1; ST1, ST2) on a desired target value (TV), and (ii) the flow control means (3) to obtain a flow of the liquid (10) through the channel (4).