Introduction
The electric
water heater uses two immersion heating elements, one near the top of the
tank and one near the bottom to heat the water. The heating
elements are electrical-resistant elements that operate in a similar fashion
to an electric stove-heating element. The unit is powered by a 220-volt circuit.
Heating Elements and Controls
Each heating element has a thermostatic switch that turns the individual
heating element on and off. Both thermostatic switches are usually set
to the same temperature. When the water temperature (at the top or
bottom) drops below the preset limit, a control switch closes to create an electrical
circuit through the heating element. The electric current
heats the element, thereby heating the water. When the water
temperature reaches its preset limit again, the heating element will turn
off. Thermostats are adjustable and are set between 120°F for
increased energy savings and scald protection.
Lower and Upper Heating Elements
The lower element maintains the water
temperature in the tank (when idle) because the water at the bottom of the
tank will cool first (heat rises). In addition, the lower element
heats the cold water entering the tank through the dip
tube (when hot water is being drawn out of the top of the tank).
When the lower heating element cannot keep
the water being drawn of the top of the tank hot (e.g. high hot water
demand), the upper element activates and will
try to heat the warmer water at the top tank as it is drawn. Note:
most electric water heaters are designed so that both elements will NOT
work at the same time. The lower element will shut off when the upper
element is active.
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