You can test them with the power off using an ohmmeter to measure resistance or with the power on using a voltmeter to measure voltage.
Electric hot water heater thermostat test.
Although most of the cases this scenario occurs for the power supply problems.
How to test a water heater element with a multimeter.
Structure of water heater.
Upper thermostat makes it possible for you to have cold water supply when you turn on the tap of hot water.
Electric water heater thermostats are a fairly simple devices that can fail from time to time.
Usually when the upper thermostat goes bad you will have no hot water at all while a bad lower thermostat makes itself known when there is only a small amount of hot water before the tap water goes cold.
If the thermostats are okay you need to test the water heater elements.
When an upper heating element or thermostat fails the entire water heater stops producing hot water.
This is important especially as open and grounded heating elements result in inaccurate tests.
To look for faults you will need to use a screwdriver.
If the hot water heater is not working one of the thermostats may be bad.
Testing is the only option if you want to determine whether or not one or both of them has failed.
The electric heater has a total of two thermostats each performing distinct functions.
When a lower heating element or thermostat fails the top thermostat and element will continue to heat water in the upper half of the tank but you will notice the hot water quickly runs out or is only lukewarm.
In this case testing the thermostat is a little bit of a technical task but not hard at all.
An electric hot water heater has two thermostats controlling two separate heating elements one in the upper half of the tank one in the lower half.
An electric water heater uses one or two heating elements to heat the water inside the tank.
Lower thermostat ensures that the hot water keeps coming and it does not turn cold when you turn on the hot water tap.
Remaining always on is the most common issue with electric water heaters.
The structure of an electric water heater is pretty simple.
If you want to test a thermostat on an electric water heater you will also need to check the heating element.
How to test water heater thermostat this case might happen for the defected thermostat.
And when it comes to thermostats the device uses two of them generally.
One should be sitting on the top of unit 1.
You will also need to check the water heater thermostat with digital multimeter tools.