The actual thermocouple on mine is just a bare metal ball. Then attach the black clamp to the gas valve. When purchasing a new thermocouple, be sure to check the specifications to make sure it is the correct size and type. Cleaning a thermocouple is not a fix for an issue, such as inaccurate readings. I understand this seems quite confusing for you. It's a usually reliable device that works in conjunction with a standing pilot, which is the little flame that, like the Olympic torch, burns while the appliance is in operation. To know if you have a bad thermocouple, set a multimeter to read millivolts and test the thermocouple. If the connections appear loose or corroded, then you will need to clean them and tighten them. The plug has a strain relief for the cable, but theres nothing to prevent the wire from spinning inside the strain relief. Look around the igniter as well and make sure there is no build-up on the burner or near the igniter. I checked that, and found zip - no voltage at all from the thermocouple. Turn the gas valve on the appliance to the Light Pilot setting. Now that is working again, it shows about 15 ohms. It may have gotten crushed or one of the wires may have broken off. You will need a wrench, multi-meter, and a flame source, like a candle or a lighter, to perform the test. If you have a gas water heater, gas wall heater or any other appliance with a gas burner that needs to cycle on and off, there's a thermocouple in your life. Were committed to providing the world with free how-to resources, and even $1 helps us in our mission. Close the fireplace access panel and restore the gas supply to the fireplace. When the thermocouple is dirty, it won't produce enough voltage to open the gas valve, this will cause the pilot light to go out after you release the bypass button. With over 12 years of experience, Gevorg specializes in residential and commercial appliance repairs as well as heating, ventilation, and air conditioning (HVAC) services. Fortunately, the plug can be disassembled. Use a lighter or torch to hold a flame under this end. Required fields are marked *. How to know if a thermocouple is bad? 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. How To Get Rid Of The Made In China Smell 7 Methods to Try! Hunker may earn compensation through affiliate links in this story. If youre still unsure or dont have a working pilot light, test the thermocouple with a multimeter. A dirty thermocouple may affect the ability of the gas fireplace to ignite. Expert Interview. customerservice@temprel.com. Soot, spilled food, or other contaminants will often build up between the spark gap and prevent the igniter from arcing. When the flame is weak, boost up the flame to reach the device. Multiple connections should be avoided in order to improve accuracy. If all heater zones show continuity then check the resistance of each zone and compare it to the value shown on your hot-runner. You should be done in under 20 minutes. Answer: Definitely, you can! However, if you need a professional to do the job, you can pay $120 to $150. Gas appliance thermocouples have a standard design. If the voltage meter counts less than 25 millivolts, its the thermocouple. Nothing lasts forever, and when the thermocouple wears out, the pilot won't stay lit and your appliance won't work. Step 5: Screw the nut tightly into place, but do not overtighten it. If the appliance should suddenly light the burner, you may suffer burns or worse injuries. Therefore, its always wise to practice proper maintenance and upkeep of your appliances. Then, when the pilot is burning brightly, release the reset button. After that, generate heat on the thermocouple. It should have a yellow tip and cover the tip of the thermocouple. By creating an account you agree to the Hunker, How to Change a Thermocouple on a Fireplace. A thermocouple is a device that produces a small electric current when it is heated. An aged heater can create issues with gas valves, control panels, or even burners. Expires 04/30/23 *Available with approved credit. I know its really hard to tell if it has started to malfunction or not. Last Updated: October 25, 2022 In newer appliances, ignition may be achieved by a sparking device or a glow bar instead of a pilot light. I can solder wires with the fine tip just fine at 260 degrees celsius, but it takes about 300 degrees to do SMD parts. Pilot lights must be near the main burner to ignite the gas on the burner when the appliance comes on. If you properly maintain your appliance and thermocouple, the thermocouple can last about 10 years. We hope that you found this information helpful. Finally, put back the thermocouple inside the box. Open the plug and see if one of the wires has been twisted off. Then again, a way too strong flame is also inaccurate. Your igniter may or may not have a pilot hole. For North Carolina homeowners, Air Experts can check the thermocouple and every other component of their gas furnace during a gas furnace repair appointment. Remember to be safe when doing repairs around your home. Ive explained everything regarding how to tell if a thermocouple is bad. The tube sits above the bracket, a nut holds the bracket and wires in place, and underneath the bracket, you will see the copper lead wires that connect to the gas valve on the furnace. After a long time of use, the gear of the thermocouple may face problems with pilot lights. First, inspect the flame. Start at the cable connector for the controller and work your way towards the tool. The thermocouple doesnt have wires. Make sure the connection is clean and dry. Lets be apart from here. We use cookies to make wikiHow great. Set your voltage meter to read voltage (V) in millivolts. By using our site, you agree to our. Remember that you are working around open flames. If so, strip back some of the insulation, cut both bare wires to the same length, and reattach the wires. Normal business hours only. Remove your thermocouple from the heater using an 8mm wrench. Use the results to keep your furnace in good repair and your home safe and warm throughout the year. It should be low, but definitely not a dead short. Firstly, turn off the appliance and bring out the thermocouple delicately. This is what a cheap K-type thermocouple looks like: Note that the wires to the thermocouple (the little metal ball at the end of the cable there in the upper left corner of the picture) are bare - they can easily be shorted by bending or twisting the wires. On 2020-07-15 by Don Gilbert The desired voltage should be around 30 to 40 millivolts. Sometimes the sporadic movement of the thermocouple can also shake its position. unlocking this expert answer. Include your email address to get a message when this question is answered. The thermocouple needs the full heat of the pilot light to create enough electrical current. Now that is working again, it shows about 15 ohms. "Very clear and simple drawings make it easy to learn the basics in a short time. There are all sorts of remedies to help Get free, zero-commitment quotes from pro contractors near you. This article has been viewed 100,018 times. Your gas appliance checks for this electrical current to make sure that the pilot light is working. Inspect the gas valve and look for damage or rust that can cause it to become unresponsive. However, many people change them out about every four years. Expires 04/30/23 Call for details. If so, unscrew them from the pins and untwist the wires. For example; a J type calibration thermocouple cannot be used on a specific application calling for a K type thermocouple. Next, take your meter and set it to ohms. Here I repair a thermocouple for my DT304 digital temperature logger using a home made small wire welder.The small wire welder is a work in progress. Fortunately, repairing a thermocouple is a relatively simple process that requires minimal tools and a bit of patience. {"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":"