Yesterday, I replaced the thermocouple with a universal thermocouple and cleaned out the dust and soot from the burner area. It will stay lit after initial light, but will go out after furnace runs. The tech found the new gas valve to have a fault, as it won't switch to "off", only pilot or on, but I don't think this has anything to do with the pilot going out. try not to bend them close to the end where it attaches to the valve and at the pilot burner. The thermocouple tells the furnace controller that the pilot light is working. Your furnace's thermocouple, if it works normally, checks to see whether the pilot light is on or off. If the pilot lights but won't stay lit, the thermocouple is probably bad. Every gas appliance with a standing pilot that cycles on and off needs a thermocouple. Don't try to adjust the mechanism or tamper with the gas line. ©2006 Publications International, Ltd. To adjust the pilot flame, turn the adjustment screw on the gas line, as directed by the range manufacturer. If cleaning the thermocouple didn’t allow your pilot light to stay lit, or cleaning the thermopile didn’t allow the pilot light to generate enough electricity to open your gas valve and ignite the burner, it might be time to replace one of them. The pilot in my gas water heater (Aquamax 205) has been going out sporadically over the last 2 weeks. Is it common for thermocouples to test fine but still not actually work? First, inspect the flame. The job of the thermocouple is to determine whether or not the pilot light is lit. When a propane heater won’t stay lit, often what is happening is that the propane heater may sense that the flame is defective in some way, triggering the propane heater’s safety functions and causing it to shut off. Thermocouple vs. Flame Sensor . M Oglesby. Try Cleaning Off Your Thermocouple if Your Pilot Light Won’t Stay Lit. This device generates a small electric signal to keep the gas valve open when the pilot is on. If the pilot light is not working, the gas control valve will not open and you won’t get any heat. Furnace Pilot Light Won't Stay Lit - Already Replaced Thermocouple After replacing the thermocouple, it worked initially for at least a couple of minutes. 0 1. After all, your thermocouple is sitting in direct flame its whole life. This has happened before, and a new thermocouple always fixed the problem. Mechanic's Assistant: Just to clarify, what are the exact lights you're talking about? Adjustments for your furnace thermocouple. If your home furnace's pilot light won't stay lit, it's possible that your thermocouple has failed and should be replaced. The easiest way to tackle this home project is to abrade the rod with fine-grit sandpaper lightly. Since the thermocouple directly allows the pilot light to get turned on it is most likely to remain on for a while. Even after trying to relight the pilot light, you still may experience it going off. the pilot won't stay lit after replacing the thermocouple. If you cannot get the pilot light on your Rheem furnace to light and stay lit, the most common problem is a bad thermocouple. If your furnace’s pilot light won’t stay on, the furnace won’t work. The thermocouple and safety shutoff do double duty, since on burners that use a pilot flame the thermocouple senses the pilot flame and won't permit the gas valve to open if the pilot is not lit. I replaced the thermocouple but after 30-45 seconds it goes out. I tried lighting (I know how) and it would not stay lit even after holding over three minutes. howdy! Maybe the pilot stays on for a moment and the furnace attempts to fire, but almost immediately shuts down. I hold the button down in excess of 3 minutes and as soon as you release, the pilot light goes out immediatly. 1 decade ago. A Broken or Damaged Thermocouple – In this instance there is something wrong with the equipment and a technician would be required to replace or repair the thermocouple in order for your pilot light to stay lit again. share | improve this question | follow | edited Oct 29 '13 at 1:23. Luckily, this is a relatively simple procedure with the right tools and equipment. tuxedo cat. Last night I replaced the thermocouple (TC), cleaned the screen, hooked it up and it still would not light. The thermocouple on a gas fireplace may eventually become clogged with dirt and soot, which can reduce the effectiveness of the thermocouple and may eventually prevent the fireplace from lighting as expected. If the thermocouple doesn't sense heat coming from the pilot light, it shuts off the gas to prevent a leak or dangerous buildup. Assuming I was in over my head, I called the plumber who proceeded to change the thermocouple and now everything is fine. 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