Electric immersion heating unit with readily removable and replaceable galvanic current control resistor

An electric immersion heating unit for use in conjunction with a metallic water heater tank provided with a sacrificial anode has the legs of a U-shaped metallic sheathed heating element extending in electrically insulated relationship through a metallic plug adapted to operatively secure the heating unit in a tank opening. A cylindrical galvanic current flow controlling resistor is positioned in a slot between a disc shaped insulator on the outer face of the head and a terminal block receiving the ends of the heating element legs. A C-shaped metallic retaining clip in a groove about the perimeter of the terminal block maintains one end of the resistor in electrical contact with the metallic heating element sheath and establishes electrical contact between the other end of the resistor and the outer face of the head to provide a circuit of fixed resistance between the heating element sheath and the tank wall.