About the Post

Jerry Hardy

Author Information

I was a Building Contractor along with owning rental properties where I did most of the repairs myself. Its my pleasure to pass on to you some of the methods I had used in the past. Hopefully, this will save you the expense of hiring a professional to do the work.

Testing Electric Water Heater Thermostat

Procedure for testing electric water heater thermostat:

Testing electric water heater thermostat is an easy procedure if the instructions  below are followed:

Turn off power

Remove both upper and lower access covers, insulation and plastic safety covers

Check reset button

Check to make sure the reset button was not tripped by pushing in the red button on the upper thermostat.



upper heater thermostat

upper thermostat


Set temperatures

Use a screwdriver to set the upper (top) heater thermostat temperature to the highest setting. Set the lower thermostat temperature to the lowest setting.

Turn the water heater power on.

Check voltage at thermostat

The voltage should be checked by placing test probes on the two wires above the reset button to make certain that voltage is coming into the heater. The voltage should be 240 volts. Now test the heater thermostat by placing the test probes on the upper element screws. The heater thermostat is defective if there is no power to the element. If there is power at the element, it is time to check the lower thermostat.


Re-set temperatures

lower heater thermostat

lower thermostat

Set the thermostat temperatures by setting the upper heater thermostat to its lowest setting and the lower thermostat to its highest setting. The upper thermostat will make a click to off as you set the temperature. If you don’t hear a click, give the water time to heat up.

Check for voltage

The next step in testing the heater thermostat is checking for voltage at the lower element. If there is voltage at the element, give the water time to heat up. Listen for a click on the thermostat as you lower the temperature setting. The thermostat is working properly if you hear the click. Continue further if you don’t have voltage at the element leads

Next, place one test probe on the top screw of the lower thermostat and the other probe on the water tank. You should have 120 volts at this position. If the upper heater thermostat is not sending current to the lower thermostat, you will not get a reading on the meter, meaning the upper thermostat needs replacing.

If you have power, follow the next step.

This is the final step in testing the heater thermostat. Hold one test probe on the water tank and the other probe on the lower screw of the thermostat. If the reading is not 120 volts, replace the thermostat.


The first thing you should do is make a sketch of the location of the wires attached to the heater thermostat and then remove all wires. Now pull back on the two metal clips which are holding the thermostat and slide out the unit. Insert the new thermostat between the two metal clips making certain that it is held tight against the tank so it will be able read the temperature of the tank. Set the temperature between 120 and 140 degrees. Reconnect the wires, tightening the holding screws firmly against the wire. If the upper thermostat is replaced, make sure the red reset button is pushed in. Attach the plastic protective cover over the thermostat followed by inserting the removed insulation. Replace the metal cover plate. Before turning on the power, make sure the tank has been filled.

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Testing Electric Water Heater Thermostat

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