Test Water Heater Thermostat

Looking for test water heater thermostat information? Hot water
heater thermostats can be tested with the power on or off.

The guide below is is for testing a water heater thermostat with
the power off. You'll need to know how to use a multimeter.

If you're comfortable testing a water heater thermostat with the power on you can go to hot water heater thermostat for instructions.


Testing upper thermostat

water heater thermostat

Turn the water heater power off.
Remove the access panels, insulation
and plastic safety covers.

Use your multimeter to be sure that
the power is off.

Turn the upper thermostat temperature
control to the maximum temperature setting.


check power on thermostat

Set your multimeter on RX1.
Place one meter probe on the bottom
left terminal (#2).

Place the other meter probe on the
terminal screw #1 just above the #2
terminal (see pic).

On an analog multimeter the needle should sweep all the way over to zero.

If you don't get a reading replace the thermostat.

If the thermostat reads good and you do not have any warm water
at all you'll need to check the upper element. You can go to the
water heater element testing page for help.

If you have a single element water heater this is the only test you'll need to do.


Upper thermostat sending power to lower thermostat

Turn the upper thermostat temperature
to the lowest setting.You should hear it
click off ( you must have above 90 degree water in the tank).

The upper thermostat should now be
sending power to the lower thermostat
(if the power were on).

For this test place one probe on  terminal #1 (see pic).
Place the other probe on the bottom right terminal screw(#4).

The multimeter needle should sweep all the way over to zero.
If you don't get a reading, replace the thermostat.


Test water heater thermostat (lower)

Testing lower thermostat

As you can see the lower thermostat
only has two terminals.

One wire coming in from the upper thermostat and one wire going out to the lower element.

To check this thermostat set the temperature to maximum. The upper thermostat must be clicked off.

To test this water heater thermostat, place a meter probe on each of the terminal screws.

The meter needle should sweep over to zero.


With the thermostat clicked off you should not get a reading.


Related pages you might be interested in:
electric water heater thermostat replacement.
water heater temperature settings.



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