Patent ID: 8649671

Claim:
A storage water heater with double cathodic protection, comprising: a water tank ( 2 ); a retaining sheath ( 3 ); a protection current generator ( 4 ); a titanium impressed current anode ( 6 ); a magnesium sacrificial anode ( 5 ), wherein the sacrificial anode surrounds the impressed current anode, and the sacrificial anode has a conformation avoiding any contact of the impressed current anode with the water of the tank, before consumption of the sacrificial anode; an insulating retaining sleeve ( 8 ) mounting the sacrificial anode ( 5 ) and the impressed current anode ( 6 ) on the retaining sheath ( 3 ); an electric circuit of cathodic polarization comprising the sacrificial anode ( 5 ) in electrical contact with the impressed current anode ( 6 ); and conductors ( 9 , 10 ) supplying power to the protection current generator ( 4 ) and connecting the protection current generator ( 4 ) to the tank ( 2 ) and to the impressed current anode ( 6 ) via the sheath ( 3 ), wherein the sacrificial anode remains electrically connected when the protection current generator ( 4 ) is electrically connected to the tank ( 2 ), and during operation, while the sacrificial anode ( 5 ) is present, the impressed current anode ( 6 ) is not in contact with the water of the tank ( 2 ), and current which passes through the impressed current anode ( 6 ) is only discharged through the sacrificial anode ( 5 ).