Electric Hot Water Heater

Electric Hot Water Heater

Repair Guide and Troubleshooting of Electric Water Heater

The electric hot water heater guide assumes that the heater was installed properly and operating as required before the development of any problem.

Electric hot water heater comes with two thermostats; the first one near the top of the tank, and the other one near the bottom of the tank. Both thermostats are covered by removable metallic cover plates. Moreover, they are firmly pressed against the metal wall of the tank.

The top thermostat often has a high limit switch that trips once the water is too hot. This shuts off electric supply to the upper as well as the lower heating elements. If you want to reset the high limit switch, simply press the red button.

With this background, below are some problems you may encounter and possible troubleshooting suggestions.

The Water Is Not Hot

Remove the cover plate of the upper thermostat and check If the high limit switch has tripped. If the switch has tripped, reset it.

Next check if there is power at the input terminals of the upper thermostat (usually marked L1 and L2). In case there is no power, check the wiring to the electric water heater or your circuit breakers.

If the problem persists, and the top thermostat is applying power to the upper heating element, check the voltage at the upper heating element. In case power is present at heating element yet the element cannot get hot, the heating element has a problem and should be replaced. However, If there is no power at the upper heating element, the upper thermostat should be replaced.

Inadequate Water Or The water Temperature Too Low

When the upper portion of the tank is hot, the top thermostat removes the power from the top heating element and transfers the same to the lower thermostat and the bottom heating element. When the lower thermostat has a problem, the tank is never heated and water supply is greatly reduced.

First check the power at the terminals of the upper thermostat where power is sent to the lower thermostat and the lower heating element. In case there is no power, replace the upper thermostat. On the other hand, if power is present at the upper thermostat, then check If the power reaches the lower heating element. If power is absent at the lower heating element replace the lower thermostat. In case power reaches the lower heating element but it does not turn hot, replace the lower heating element. A broken dip tube may as well be the source of the problem. Check if the dip tube is broken and replace it.

The Water Is Too Hot

One of the thermostats could be defective. First check the power supply at the upper heating element. If there is power at this element, the upper thermostat is definitely defective. Next check that there is power at the bottom heating element. If there is power, the thermostat has a problem.

You should also check if the thermostats are firmly pushed against the tank.


The TPR valve operates if either the pressure or the temperature gets too high. Where the inlet is directly fed from the mains with no pressure relieve valves, then the water becomes hot, it expands and the water flows back towards the main. In case of a blockage due to a defective valve or bypass, the increased water volume does not have anywhere to flow to and the pressure dramatically increases.

If you place an expansion tank in line at the water inlet, it will provide a place for the increased volume thereby preventing the operation of the relief valve.

It is also possible that the pressure of the city water has increased beyond the setting of the relief valve.

Banging or Popping Noise

Accumulation of scale on the heating elements can lead to various noises during the heating process. If you here a banging or popping sound, remove the heating elements and clean or replace them.


Some bacteria can react with the magnesium anode rod. This leads to production of a gas that smells like rotten eggs. Clean the tank with chlorine bleach or change the anode rod to aluminium.

Leaking Tank

The tank must be replaced at once.

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