The hot water heater element wires to the thermostat, and the thermostat regulates the temperature of the water. When the water temperature inside the tank lowers to a temperature less than the thermostat setting, the thermostat allows electrical current to pass through the heating element. The electrical current flowing through the element heats the water, raising the temperature to meet the thermostat temperature setting.
Turn off the 30-amp double-pole circuit breaker inside the main electrical panel that supplies power to the water heater.
Remove the two screws holding the access panel to the side of the water heater and lift the panel off the tank. Remove the insulation from behind the access panel to access the thermostat and element.
Attach the yellow wire from the thermostat around one screw on the face of the element and the blue wire from the thermostat around the remaining screw on the face of the element. Tighten both screws to hold the wires securely to the water heater element. Unless specifically marked on the element, either wire can be attached to either post.
Replace the insulation over the thermostat and element and reattach the access panel. Turn on the 30-amp double-pole circuit breaker inside the main electrical panel.