I Have A Dual Element Electric Hot Water Heater. No Power To The Lower Element. Can You Explain?


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Dual-Element Water Heaters
Dual-element electric water heaters have two thermostats, one for the top element and one for the bottom element. The top thermostat controls both the upper element and the lower thermostat. The two elements do not operate at the same time.

Water heaters are filled from the bottom. A fill tube goes from the intake at the top of the tank to the bottom of the tank, so that cold water enters at the bottom, leaving hot water at the top, where it exits the tank at the outlet as needed.

The upper element is the primary element. It operates first to heat water at the top of the tank and make it available for use. Starting with a tank of cold water, the primary thermostat at the top turns on the upper element and keeps it on until the water temperature reaches the setting on the thermostat.

The primary thermostat turns off the upper element and sends power to the lower, secondary thermostat which turns on the lower element. The lower element heats the water at the bottom of the tank until it reaches the control setting temperature. All the water in the tank is now hot and both elements are off.

Water is used from the top of the tank, which brings cold water into the bottom of the tank and pushes hot water at the bottom towards the top. Since the upper thermostat is still off, the lower thermostat turns on the lower element again to heat the additional cold water until it reaches the temperature setting.

If enough hot water is used so that the tank is once again filled with cool water, the upper thermostat will turn on the upper element and turn off the lower thermostat, starting the process over again.

Deducing from the above description, "if" you have NO POWER TO EITHER element, press the red dot reset button in the thermostat of the top element housing.  If still no power to either element or the upper thermostate/reset housing, check your power supply to the whole water heater (curcuit breakers, connections, etc.)
If POWER TO TOP ELEMENT ONLY, then suspect that the top tank is cold and the bottom element has been turned off while the top element is on, as the system is operating properly.  Constantly monitor the voltage to the bottom element to see that when the top tank gets hot, the bottom element receives power as the top element looses power, to indicate that the system is operating properly.

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