How to replace electric heating elements on the water heater. See what the most common causes of the water heater element failure are, testing and repair tips. How to choose the right electric heating element and what factors should be considered when buying, for the long and reliable water heating in residential applications.
Heating elements are important parts of the electric water heaters that are designed to transform electrical energy into heat – therefore heating the water. Most of the time they are made of copper, stainless steel, titanium, and Incoloy.
Every electric water heater is equipped with one or two heating elements but it depends on the size of the unit.
The following factors should be taken into account when
choosing the correct heating element for replacement.
Element flange style
Voltage and wattage
Looking at both older and newer models of water heaters, there
are two different types of electric heating elements providing
different attachment to the heater’s body:
Flange-type (universal flange, flat flange, round head)
Most of the electric water heaters two heating elements, upper and lower, where the screw-in type is the most common type, as it is easy to install, remove and service. Models with the smaller capacity, including point-of-use models, have only one heating element. Water heater element with the flange (bolt-in type) is another type but is used less.
Both types are immersion type elements, with the U-shape design, heating water when energized and providing energy efficiency close to 100%.
Manufacturers will use various types, different in voltages and watt densities, where 240 volts and 4500 watts are the most common. The voltage and wattage can be checked on the rating plate of the water heater.
Each element has a designated thermostat where you can adjust the temperature, usually between 120 F and 140 F. The thermostat setting is what allows the heating element to provide more or less power or lower and higher temperature of the outgoing water. If the thermostat becomes damaged or stops working, water will be either too hot or there will be no hot water at all.
The upper thermostat is the main one as it controls the heat
generated by both elements. It comes with the High Limit Switch, with
the reset button, and it shuts down the heater if the temperature
becomes too high.
When selecting the best electric water heater for your home, you will have an option to buy a unit with the low or high watt density elements.
Low-watt density heating element is what you should look for,
as it provides an even distribution of heat, which makes it last
longer. Even better is the ultra-low watt-density, a premium grade
element that can reduce the limescale build-up and dry-firing.
In order to check is there a problem with the heating element(s), simply turn the hot water tap on.
If hot water is running for a short time before it gets cold,
the problem is with the bottom heating element. Even if the upper one
is still working, it will heat up water only at the top of the tank but
will eventually run out fast.
If water is always cold at the fixture, it looks like both elements are gone and have to be replaced.
Heating elements can break over time because they will turn on and off quite often, keeping the water at the set temperature, either using hot water or not.
Note: Keep in mind that the electric heating elements with the higher wattage require more Amps and heavier gauge wire.
Below are the most common reasons for the heating element
failure, so before troubleshooting, it is always a good idea to check
and make sure that the circuit breaker is on and not tripped. Also, by
pressing the reset button located right above the thermostat could fix
If you live in the area with the hard water condition, you probably had problems with the mineral deposits and limescale. The sediment build up on the water heating elements will prevent heat transfer to the water at the proper rate, thus overheating and causing the element burnout.
The solution to this problem is to clean the electric water heater element regularly, by brushing away the scale build up. Another option when selecting a new water heater is to buy a unit with the Incoloy type which lasts longer and have better resistance to the sediment build-up.
Another indication of the sediment buildup on the heating elements is the “sizzling” or “hissing” sound, which develops when water being trapped next to the element boils water to steam.
Dryfire problem happens when the water heater elements while working, are exposed to the air pockets. The part which is in contact with the air will get an excessive amount of heat. It takes several seconds for the copper heating element to burn out. They are designed to operate only when submerged in water.
Dryfiring can be recognized as the element shaft is annealed so soft that you can bend it with your fingers and the plastic element is melted.
The recommendation is always to fill the tank of the electric water heater and bleed all the air from the system before turning the power ON. The problem is not covered by the manufacturer's warranty.
If more than the design voltage is supplied to the heating element, the element will burn out. One of the examples is the high voltage during the lighting or sometimes caused by the electric utility company. If there is less voltage provided, the heating element will work but will be less efficient.
Other problems that might affect the proper work are related to the vibration break, open circuit or split sheath.
Turn the power OFF to the water heater, on the electrical panel.
Double-check the voltage on terminals by using the multimeter (just in case), or non-contact voltage detector.
Remove an access panel, insulation and plastic cover.
Disconnect wires from the heating element.
Set the multimeter to OHM settings.
Put one test probe on the terminal and the other probe on the steel tank. If the OHM multimeter needle moves, the element is grounded and needs to be replaced. Make sure to test both screws of the element.
You can also put one probe on one terminal and with the other probe touch the other terminal and if the OHM multimeter needle doesn’t move (no reading), the element is bad and should be replaced.
One of the indications that the element has grounded, is if the water is getting extremely hot and heater trips the circuit breaker constantly.
Continuity through the heating element indicates the current flow and heating. If there is no continuity, the electric circuit is open, so the electric current cannot flow.
If the element is good, the reading should be between 10 and 16 ohms, depending on the wattage of the element.
Note: If you don’t feel comfortable with the repair, always contact the professional plumber.
Before you start replacing the broken electric water heater element on the water heater, make sure to use the same type with the same wattage and voltage. Check the element terminal block for the proper rating.
Note: Check if the breaker has tripped or if the fuse is blown in the fuse box.
For the screw-in type heating element, as the most used type, a large socket wrench is needed for the proper removal and installation.
Turn the water heater OFF on the electric service panel.
Shut OFF the water supply and drain water below the broken element.
Locate the broken electric heating element and make access by removing the insulation and cover.
Make sure that the power is OFF by measuring the voltage on the thermostat terminals, which powers the element. The reading should show 240 or 120 volts.
Disconnect the wires.
Remove the electric element using the large socket with the hole or wrench. If it doesn’t turn, use a longer leverage tool.
Install a new rubber gasket and the heating element.
Reconnect the wires and make sure they are snug and clean of debris and rust.
Fill the tank up (make sure the drain valve is turned off and garden hose removed).
Open the hot water tap until all the air is out.
Make sure there is no leak.
Resume the power.
Heating elements are the most important parts of the water heater – they are designed to heat water. Without it, there will be only cold water. While the price of the heating element is low, replacing the heating element is an easy job for handymen; it requires basic knowledge about plumbing and electricity. But if you don’t feel comfortable working on the heater, hire a professional.