A device (18, 18') for heating a liquid, comprising: a tank (20, 20'), electrodes (22, 23), and a first inlet pipe (30d, 30b), wherein said first inlet pipe (30d, 30b) is connected for supplying entering liquid to said tank (20, 20') from a supply of entering liquid, wherein said tank (20, 20') holds said entering liquid and said electrodes (22, 23); characterised in that the device further comprises: a source of electrolytic material switchably connected for adding said electrolytic material to said entering liquid in said tank (20, 20') or a source of electrolytic material switchably connected for adding said electrolytic material to said entering liquid in said first inlet pipe before said entering liquid enters said tank (20, 20'), wherein said electrolytic material added to said entering liquid provides a conductive liquid, wherein said electrodes (22, 23) are connected to provide a current flowing in said conductive liquid in said tank (20, 20'); an electrical parameter sensor for detecting a parameter of electrical energy dissipated in said conductive liquid; and a controller connected to automatically add said electrolytic material to said tank (20, 20') or to said entering liquid in said first inlet pipe if said electrical parameter sensor detects said electrical parameter differing from a set point. a tank (20, 20'), electrodes (22, 23), and a first inlet pipe (30d, 30b), wherein said first inlet pipe (30d, 30b) is connected for supplying entering liquid to said tank (20, 20') from a supply of entering liquid, wherein said tank (20, 20') holds said entering liquid and said electrodes (22, 23); characterised in that the device further comprises: a source of electrolytic material switchably connected for adding said electrolytic material to said entering liquid in said tank (20, 20') or a source of electrolytic material switchably connected for adding said electrolytic material to said entering liquid in said first inlet pipe before said entering liquid enters said tank (20, 20'), wherein said electrolytic material added to said entering liquid provides a conductive liquid, wherein said electrodes (22, 23) are connected to provide a current flowing in said conductive liquid in said tank (20, 20'); an electrical parameter sensor for detecting a parameter of electrical energy dissipated in said conductive liquid; and a controller connected to automatically add said electrolytic material to said tank (20, 20') or to said entering liquid in said first inlet pipe if said electrical parameter sensor detects said electrical parameter differing from a set point. a source of electrolytic material switchably connected for adding said electrolytic material to said entering liquid in said tank (20, 20') or a source of electrolytic material switchably connected for adding said electrolytic material to said entering liquid in said first inlet pipe before said entering liquid enters said tank (20, 20'), wherein said electrolytic material added to said entering liquid provides a conductive liquid, wherein said electrodes (22, 23) are connected to provide a current flowing in said conductive liquid in said tank (20, 20'); an electrical parameter sensor for detecting a parameter of electrical energy dissipated in said conductive liquid; and a controller connected to automatically add said electrolytic material to said tank (20, 20') or to said entering liquid in said first inlet pipe if said electrical parameter sensor detects said electrical parameter differing from a set point.