Necessary cookies are absolutely essential for the website to function properly. It consists of a heat sensor connected to a solenoid; when the sensor is not heated by the pilot flame, the solenoid closes the gas supply line. We also use third-party cookies that help us analyze and understand how you use this website. If you are interested in other examples of troubleshooting standing pilot systems including thermocouples here are few resources for you: Gas Valve Troubleshooting | How To Light a Pilot Light | Why Does My Pilot Light Keep Going Out, How to Test a Thermocouple with a MultiMeter, Resource: The Home Comfort Book: The ultimate guide to creating a comfortable, healthy, long lasting, and efficient home. % of people told us that this article helped them. wikiHow is where trusted research and expert knowledge come together. Use a 7 ⁄ 16 in (11 mm) wrench to rotate the nut counterclockwise and free the thermocouple. If the thermocouple is testing good then you likely have a bad gas valve. Last Updated: December 23, 2020 When it stops working, the furnace’s pilot light also turns off. It’s function is to measure the oxygen level in the room. You also have the option to opt-out of these cookies. If the thermocouple is putting out 26 mV then something is wrong with the valve. The thermocouple emf is measured with a high impedance voltmeter. This is a sort of “trick” step. The push button must be depressed through the whole check. You have to be careful when cleaning it. I’m sure you write a lot of helpful articles. An oven thermocouple is seldomly found on modern ovens. Everything is in alignment to the flame. With the thermocouple being disconnected from the gas valve for checks, the pilot valve should not stay open and the flame should go out when the push button is let up. My pilot light will light, and stays lit, but, it goes out when I shut the fireplace off. 1 millivolt is equal to 1/1000 of a volt. Air that you need to live. Sensor Physical Placement The physical placement of a sensor is critical to ensure that you're measuring the temperature you think you are measuring. References. Before you replace it, though, it's a good idea to test it with a voltmeter to make sure it's actuall… By signing up you are agreeing to receive emails according to our privacy policy. It is consuming too much air. I have an un-vented gas fireplace. Since I cannot locate a thermocouple that looks like the one on this assembly, I would have to modify the bracket so that it might receive an ‘aftermarket’ thermocouple. And I would not advise using a battery to test the valve. Another option is to call a heating repair person near you. After twisting the wires, trim the two ends to prevent them from sticking out at an angle. Good luck! Replace the Thermocouple. The 4-20 mA output is a high-level signal as compared to a thermocouple. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/0\/04\/Test-a-Thermocouple-Step-1.jpg\/v4-460px-Test-a-Thermocouple-Step-1.jpg","bigUrl":"\/images\/thumb\/0\/04\/Test-a-Thermocouple-Step-1.jpg\/aid9649384-v4-728px-Test-a-Thermocouple-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"