First of all, an electric water heater uses a heating element immersed in the tank water for heating. When electric current passes through the heating element, it gets hot.
A dual-element heater has an upper and a lower heating element. There are two thermostats physically attached to the metal tank, one to control the upper element, and one for the lower.
Only one element is on at a time. From a cold start, the upper element (I believe) is powered. The upper thermostat also has a power feed to the lower thermostat and element. While the upper element is heating, the lower thermostat and element are disabled. Once the water in the upper part of the tank reaches the upper thermostat's set cutout temperature, it enables the lower thermostat and heating element. Now the lower thermostat heats the rest of the water in the tank, then cuts off power to the lower element.
Remember that heat rises and hot water is less dense than cold water. This will make your hot water rise to the top, where it is drawn out. While both heating elements may be the same, the upper thermostat is different from the lower. The two cannot be substituted or interchanged.
Only one element comes on at a time to reduce the electrical drain on your system and to provide more stable water temperature control.
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how does a duel electric element hot water heater work?
First off, there is no such thing as a "hot water heater". If the water is already hot, why does it need to be heated? Second, I have never heard of a water heating device being used in a duel. Are the participants using squirt guns and filling them with hot water?? I guess that would be a less deadly way of settling a dispute. If, on the other hand, you are talking about a DUAL element water heater, the explanation given by Ronald Greene is more than adequate.
Have you checked the circuit breaker to make sure that it isn't tripped?If you have power then there is only three things it could be the thermostat, plugged supply pipes or your water heater is completely full of settlement.If you get water when you turn on the hot water faucet then we can rule out plugged pipes.I would say then that you should have your thermostat checked out. And hopefully the water heater isn't full of settlement but you could check that by opening the drain valve located towards the bottom of the unit.If that's okay it would almost have to be the thermostat.If all else fails you will have to replace.Take care and may God bless you.