Electric Water Heater Troubleshooting

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Electric water heater troubleshooting is easy when you understand the heating process, know plumbing and appliances. What you need to know before doing any repairs is how electric water heater works and what are the main components.

This is a heating expert guide written especially for troubleshooting electric water heaters with 30, 40, 50 gallons capacity and larger ones, for residential use.

Elements and how they work

  • Cold water from house plumbing enters the heater tank, through the dip tube and fills the tank from bottom up.

  • The upper thermostat with pre-set temperature calls for heating and turns on the upper heating element to heat the water.

  • Water is getting warmer and when it reaches the set temperature the top thermostat switches power to the bottom thermostat and it applies power on the bottom heating element until it reaches the set temperature.

  • If the hot water in the top of the heater tank is too high the red button will trip and cut the power to both heating elements.

  • Once you open the tap for shower or dishes, hot water is drawn from the top of the unit, through plumbing to the opened faucet.

  • For draining and tank flushing, there is a drain valve at the bottom of the tank.

  • Inside the heater tank, there is sacrificial anode rod that prevents corrosion due to the heating process. It is replaceable.

Now, when you know the basics, it is much easier to do electric water heater troubleshooting. We will assume during this presentation that electric heater was properly installed and was function correctly before the problem occurs.

Problems and troubleshooting described below are related exclusively to electric heaters, tank type. For water heaters troubleshooting repairs with common problems, for both gas and electric units go back here.

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

Common problems and troubleshooting

Troubleshooting No hot water problem

Check is there a power at all; the main switch might be off. If you suddenly have no hot water, your water usage may be exceeded the tank capacity. If that is the case, wait for the heater to recover.

Another solution might be; try pressing the red, reset button on the upper thermostat. If after 10 min you still don't have hot water, check is electricity being delivered to the appliance; check the heater's pair of circuit breaker in the breaker panel.

If breakers are ON, check if there is a voltage using the voltage tester, at the input terminals of the upper heating element. If there is no voltage the thermostat has to be replaced; if there is voltage the heating element needs replacing.

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Other possible causes might be as follows:

  • Improper wiring - rewire per wiring diagram found in the user manual

  • Shorted wiring - rewire

  • Circuit overload - reduce load or provide adequate circuit

  • Grounded element or thermostat - rewire

  • Heat build-up due to loose wire - tighten wire connections

  • Defective high limit switch - replace

If your electric heater was running for too long, the odds are insufficient hot water for your shower and if it is happening often, you have an undersized heater. Depending on the recovery rate, you have to wait for a while for water to be reheated.

Another cause is that the thermostat is set too low especially in the winter time and in the cold room, where simple solution is to increase the temperature, not to high, as the too hot water can lead to scalding and burns.

Your lower heating element or lower thermostat also might be faulty so you have to replace them.

If the scale is formed on the heating elements because of the hard water action, the contact surface between fully immersed elements and water is decreased and needs to be cleaned.

Improper, loose wiring or thermostat is not installed properly. Thermostat has to be installed flush with the tank so it cannot read the temperature accurately.

Troubleshooting high pitched whining

As the electrical heating elements are used over months and years of work, water condition in your home and area plumbing (hard water) caused the buildup of scale and mineral sediments on electrical heating elements.

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

To fix a problem, remove and clean 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.

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