Cathodic corrosion and dry fire protection apparatus and methods for electric water heaters

A method of protecting a liquid heating apparatus from operational damage, the liquid heating apparatus having a corrodible vessel adapted to hold liquid to be heated, and an electric heating element extending through an interior portion of the corrodible vessel and having an electrically conductive filament sheath, the method comprising the steps of:

• sensing a magnitude of a voltage potential between the electrically conductive sheath and the corrodible vessel;
• and
• utilizing a protection system operative to detect the voltage potential magnitude and use the voltage potential magnitude in (1) inhibiting corrosion of the corrodible vessel and/or (2) preventing dry firing of the electric heating element, wherein the utilizing step includes the further steps of:
• sequentially (1) measuring the magnitude of the voltage potential between the electrically conductive sheath and the corrodible vessel in the absence of an impressed voltage on the electrically conductive sheath, (2) recording the magnitude of the voltage potential if it is above a predetermined value thereof, (3) applying the impressed voltage potential to the electrically conductive sheath equal in magnitude to the recorded voltage potential magnitude plus a predetermined additional impressed voltage potential magnitude, and (4) terminating the impressed voltage to the electrically conductive sheath.