Electric Water Heater Troubleshooting and Repair Guide

Electric water heater troubleshooting guide is easy to use guide, helping homeowners fixing the most common problems found on conventional and most used tank-type models. Find out how to repair no hot water, not enough hot water, hot water too hot, high pitch noise, heating elements and thermostat issues and other problems.

Electric hot water heater troubleshooting - Safety first

Safety

A qualified professional is recommended for a safe, easy and fast troubleshooting and repair of any problem on your electric water heater.

One of the most common reasons why one electric water heater doesn't work is that there is no power on the heating elements. There are different reasons for this problem so before any work has been done, it is important to turn OFF the power to the unit (circuit breaker or fuse). And, always check with the multi-meter are the elements energized - just to be sure.

Troubleshooting problems such as leaking or dripping, noise, sediment build-up, rotten egg smell, discolored water, bulging, corrosion, high pressure and sudden temperature increase and other issues are explained in this guide, in details.

How does the electric water heater work

  • Cold water from the house plumbing enters the heater tank, through the dip tube and fills the tank from bottom up.
  • The upper thermostat with the pre-set temperature calls for heating and turns on the upper heating element to heat the water to the desired temperature.
  • Water is getting warmer and when it reaches the set temperature the top thermostat switches power to the bottom thermostat and bottom heating element to maintain the desired temperature.
  • If the hot water at the top of the heater tank is too high the red reset button will trip and cut the power to both heating elements.
  • Once the tap is open for shower or dishes, hot water is drawn from the top of the unit, through plumbing and to the open faucet.
  • As the set temperature is met, water heating stops.
  • While the hot water exits the tank, cold water gets in and mixes with hot water, lowering the tank temperature. As the temperature drops below the set temperature on the thermostat, thermostat energizes the heating elements again so hot water can maintain its temperature.
  • TPR or temperature pressure relief valve prevents extreme pressure in the tank, helping the excessive air or water to get out.
  • For draining and tank flushing, there is a drain valve at the bottom of the tank. It is made of plastic or metal.
  • Inside the heater tank, there is a sacrificial anode rod that prevents deterioration of the metal tank and other elements due to corrosion.

Now, when you know the basics, it is much easier to perform electric water heater troubleshooting. For the proper repair, it will be presumed that unit was properly installed, and it met the manufacturer recommendations, codes and best practices.

Note: Basic electrical knowledge is necessary to safely troubleshoot an electric water heater.

Common problems and solutions

Troubleshooting no hot water or not enough hot water

Check the power. Confirm that the there is a power supply to the unit. If not, the main switch might be off, or the circuit breaker is tripped or the fuse is blown.

Reset button. Press the red, reset button on the upper thermostat. If after 10 min. you still don't have hot water, check if the electricity is being delivered to the appliance; check the heater's pair of the circuit breaker on the breaker panel.

Check the voltage. If breakers are ON, use the voltage tester to check if there is any voltage at the input terminals of the upper heating element.

The voltage should be 220/240 V or 110/120 V, depending on the model. If there is no voltage, home's electrical system should be checked or thermostat replaced. If there is voltage but still no hot water, the heating element might have burned out so it has to be replaced.

Recovery rate. If there is a sudden interruption in hot water delivery, water usage may be exceeded the tank capacity. If that is the case, wait for the heater to recover. If this is an ongoing problem, the water heater might be undersized... so consider buying a bigger one, or tankless.

If the elements are too small, replace them with the correct model (recommended by the manufacturer); for the lime formation on the elements perform the tank flush; and if the dip tube is broken replace it.

Continuous operation. This problem is related to an undersized tank, small heating elements, faulty thermostat or leaks in faucets, around heat traps, fittings or heating elements. Leaking can be easily fixed by using the right sealer, Teflon tape and by tightening the element.

- Find Plumbers In Your Area -

Get Free Plumbing Quotes!

The reasons for the element and thermostat failure are:

  • Improper or loose wiring - rewire per wiring diagram found in the user manual.
  • Shorted wiring requires rewiring.
  • Circuit overload - reduce load or provide adequate circuit.
  • High / low voltage.
  • Grounded element or thermostat - rewire.
  • Heat build-up due to the loose wire - tighten wire connections.
  • Defective high limit switch - replace.

The thermostat is set too low. If the thermostat is set too low and the incoming cold water has a lower temperature, hot water won't be hot enough. A simple solution is to increase the temperature, but not too high, as the extreme temperature can lead to scalding burns. Follow the manufacturer recommendation - safe temperature is in the range from 120 F to 125 F.

Also, a lower heating element or lower thermostat might be faulty so it must be replaced. Make sure the thermostat is firmly attached to the outside tank surface.

Limescale build-up. If the scale is formed on the heating elements because of the hard water condition, the contact surface between the immersed elements and water is decreased and needs to be cleaned.

Loose connections. Improper, loose wiring or thermostat is not installed properly. The thermostat has to be installed flush with the tank, firmly attached, so it can read the temperature accurately.

Water is too hot

Electric water heater troubleshooting also involves ensuring that the temperature of hot water is safe, and not high. For example, if the temperature of hot water is 140 F, it takes less than 5 seconds for scalding burns, while for 155 F about 1 second.

Beware of the scalding water. Especially if kids are around. Hot water is an issue. Check the thermostat, so the right, safe temperature is set. The thermostat has to be properly installed on the tank (flush). The element should be checked if grounded.

One of the solutions is to install a mixing valve so the outgoing hot water has a temperature that is safe and always constant when using.

The breaker tripping

Check the electric wires, they might be shorted. Check if the heating element and thermostat are grounded. Is the breaker correct size?

Heating elements burned out

Unless the water heater is equipped with the dry-fired heating elements, the standard type can easily and instantly burn out if it is not fully submerged into the water (the tank is not full of water), even if the element is partially exposed to the air.

In such a case, the element shaft becomes so soft that it can be bent by hand, a hole is burned through the surface or there are signs of melting.

Except mentioned above dry-firing, water heater elements can fail, some sooner some later, due to; lime scale build-up, voltage spikes or lighting. Find out more about element failures and solution here.

Troubleshooting noises

As water heater operates for months and years, water condition in your home and area plumbing (hard water) can cause the limescale and sediment buildup on the electrical heating elements. This is one of the main reasons for the high pitched whining or hissing noise.

The tank water contains minerals that form the limescale on the element. When water is heated and is trapped inside the scale it will form steam, making the hissing sound.

Note: recommendation is to perform the preventive maintenance and flush heater regularly.

To fix a problem, remove and clean the heating elements from the scale buildup. If it doesn't help, replace them.

Another solution is to install low-watt density heating elements with a larger contact surface to transfer heat to water more efficiently.

Humming sound is another "issue" that is caused by the vibration of the electric current when the element's loop is installed horizontally. To eliminate the humming noise, make sure that the element loop is positioned vertically and is tightened.

As it can be seen from above, electric water heater troubleshooting is not simple and requires an extensive knowledge and skills, using the necessary tools. With the voltages of 240 V, it can be dangerous to work on it, if do not have experience. This is why it is recommended to call a professional.

Related articles

Tankless problems and solution
RV water heater repair
Solar water heating troubleshooting guide
Gas water heater troubleshooting
Electric water heater repair

emergency plumber
water heaters