Gas Water Heater Thermocouple Test

For testing a thermocouple you first have to remove it from the furnace water heater or gas appliance where it is installed.

Gas water heater thermocouple test.

A thermocouple uses the heat from a flame to produce a millivoltage that controls a gas valve. 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. First remove the thermocouple.

That is simply a test to check the meter for continuity. You can test this yourself using a multimeter but you may need a helper to keep the pilot flame burning while you do it. Secondly turn on the meter and set it to ohms. If the pilot light doesn t stay lit check the gas water heater thermocouple by keeping the pilot button depressed.

Touch the two leads together from the meter and you should get a reading close to zero. First shut off the gas valve on the water heater and the gas valve on the gas line near the heater. If you re still unsure or don t have a working pilot light test the thermocouple with a multimeter. Finally now turn the meter to volts.

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. Measure the current by using the multimeter device set on millivolts. A gas water heater in boise baton rouge buffalo or boston uses a thermocouple that includes a probe attached to a copper tube that screws into a port on the gas valve. Gas appliance thermocouples have a standard design.

The burner typically sits loosely or under clips in the burning chamber and just slides out. Here s how to test a suspected thermocouple in a gas operated water heater. Usually a lighter will suffice for the test. For a basic test attempt to turn on the pilot light again.

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. 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. One probe of the meter should be connected to the copper sheath of the thermocouple and the other to the gas valve. When it stops working the furnace s pilot light also turns off.

Multimeter thermocouple test procedure. Then unfasten the three nuts that hold the thermocouple and the two gas tubes to the valve. The thermocouple is a vital safety feature for many gas appliances. Diy hot water heater repair.

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. With the leads apart you will read infinity.