It is comprised of two different types of metal which react differently to heat and expand at different rates signaling to the water heater when to turn on or off.
Gas water heater thermocouple test.
Once it is removed you will need a multimeter that needs to have the ability to read millivolts and a source of fire.
For a basic test attempt to turn on the pilot light again.
Touch the two leads together from the meter and you should get a reading close to zero.
If the thermocouple is working you should be able to measure 30 to 40 millivolts of voltage at the connection end of the tube when the pilot flame is on.
Measure the current by using the multimeter device set on millivolts.
A thermocouple is a safety device that helps control the gas supply in gas heated furnaces.
Secondly turn on the meter and set it to ohms.
A thermocouple uses the heat from a flame to produce a millivoltage that controls a gas valve.
The thermocouple is a vital safety feature for many gas appliances.
The burner typically sits loosely or under clips in the burning chamber and just slides out.
If you can t light the pilot the problem most likely lies with the gas control valve or the gas flow itself not the thermocouple.
If you re still unsure or don t have a working pilot light test the thermocouple with a multimeter.
For testing a thermocouple you first have to remove it from the furnace water heater or gas appliance where it is installed.
One probe of the meter should be connected to the copper sheath of the thermocouple and the other to the gas valve.
Multimeter thermocouple test procedure.
Diy hot water heater repair.
When it stops working the furnace s pilot light also turns off.
How to test a thermocouple.
With the leads apart you will read infinity.
First remove the thermocouple.
Then unfasten the three nuts that hold the thermocouple and the two gas tubes to the valve.
If the pilot light doesn t stay lit check the gas water heater thermocouple by keeping the pilot button depressed.
Light the pilot by pressing and holding the pilot light button on the gas control valve.
Use a small flame source to test a thermocouple with a multimeter.
Gas appliance thermocouples have a standard design.
Usually a lighter will suffice for the test.
Finally now turn the meter to volts.
That is simply a test to check the meter for continuity.
The water heater thermocouple is a device that monitors temperatures in the water heater to determine whether it needs to heat up or turn off the heat.
You can test this yourself using a multimeter but you may need a helper to keep the pilot flame burning while you do it.
