Water Heater Thermocouple Tester

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

Water heater thermocouple tester.

Light the pilot by pressing and holding the pilot light button on the gas control valve. Here s how to test a suspected thermocouple in a gas operated water heater. The reading should be between 25 and 30. Usually a lighter will suffice for the test.

Acceptable range for most water heat. Anything under or hovering around the 20 millivolts mark means the thermocouple needs to be replaced. Thomas seeback discovered it in 1821. Thermocouple thermometer 50 300 degree industrial temperature meter j k t e n r s type thermocouple dual channel temperature meter tester lcd backlight 3 9 out of 5 stars 7 22 99 22.

Discretion should be used if the reading is between 21 and 25. 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. Originally it had a ratio of copper and nickel and was labeled a coppel copper nickel element. Once it is removed you will need a multimeter that needs to have the ability to read millivolts and a source of fire.

If the pilot light doesn t stay lit check the gas water heater thermocouple by keeping the pilot button depressed. In the early 1900s honeywell applied it to the safety gas valve. 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. A thermocouple is a safety device for a standing pilot gas system.

Pilot light keeps going out. How to test a thermocouple. Measure the current by using the multimeter device set on millivolts. Thermocouples designed for residential gas appliances such as fireplaces water heaters and furnaces are made for 30 millivolts.

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. 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. To make certain the thermocouple is bad you have to test it. How to test a thermopile s voltage using a multimeter.