Electric Water Heater Guide
This page is intended to serve as a brief overview of a typical electric
water heater and how it works.
Both electric and gas water heaters have similar tanks. The inner shell of a water heater is a heavy metal tank containing a glass lining. The glass lining is to stop the metal portion of the tank from developing rust. They typically hold 40 to 60 gallons of hot water at around 50 to 100 pounds per square inch (PSI). The exterior of the tank is covered in an insulating material such as polyurethane foam and over that is a decorative outer shell and possibly an additional insulating blanket.
What is a Water Heater Element?
An element is a part used to heat water in electric style water heaters. First, a metal element (pictured below) is submerged in the water within the tank. Next an electric current is run through the metal alloy and heat is given of as a result.
In almost all residential style electrics there will be two elements; an element towards the top of the heater and one towards the bottom. These are regulated by two separate thermostats, an upper and a lower. The elements do not run simultaneously. They alternate between top and bottom. There are also smaller ‘utility’ style water heaters with a single element but these are sold less frequently.
Electric water heaters elements are manufactured in various wattage’s (such as light bulbs.) The popular style today is a screw-in version, but a four bolt flange style is also very common. The traditional residential heating element is 4500 watts/240 volts.
What is the Control Circuit?
The standard control circuit consists of a high limit control switch with a reset button, upper thermostat, lower thermostat, two heating elements, and wires. The upper thermostat first sends electrical energy to the upper element until the water temperature in the upper third of the tank reaches the thermostat setting. Power is then transferred to the lower element until the remaining water reaches the lower thermostat setting.
If the water temperature exceeds 170°F, the high limit control switch will trip, shutting off power to the elements.
Single element water heaters will have one element mounted at the bottom of the tank, controlled by a single thermostat and high limit switch.
How does an Electric water heater work?
Below is a step by step walk through of how the typical electric water heater works when there is a call for hot water in a home for a typical residential heater.
Thermal expansion will occur as the water rises in temperature. Please see the Expansion Tank Flyer for more information on that topic.
There is also something called an anode rod inside the tank. It is a metal rod made of magnesium or aluminum that's formed around a steel core wire. They are designed to attract corrosive elements in the water, thereby diminishing corrosion in the possible vulnerable small sections of exposed steel in the liner.
Lee & Bradford White provide a few great options for trouble shooting and diagnosing issues with a water heater. Below are the top three:
A customer can call one of our Branches and talk to one of our Inside Sales Team Members.
They can also go to the Gas Water Heater Trouble Shooting Page on the Bradford White website. There are
many great resources available there.
Bradford White also has a Technical Service Help Desk Phone line available 24 hours a day, 7 days a week.