how to fix a bad thermocouple

Last Updated: October 25, 2022 The following are the six most common causes of thermocouple measuring errors, followed by ways to rectify them: 1. Then lets get your work done! Your thermocouple voltage should be between 25mV and 30mV. Must present coupon at time of service. FIND LOCAL CONTRACTORS. 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. We hope that you found this information helpful. It should be low, but definitely not a dead short. Others require that you push the gas valve in to open the valve to the pilot light. Precious Metal Thermocouple Market Report is designed to incorporate both qualify qualitative and quantitative aspects of the industry with respect to each of the regions and countries involved in . In furnaces and water heaters, and in some ranges and dryers, the pilot light is accompanied by a safety device called a thermocouple -- a heat sensor that turns the gas off if the pilot flame is extinguished. Gevorg Grigorian is an Appliance Repair Specialist and the Owner of G and R Appliance Repair in Los Angeles, California. Theres about three ohms of resistance across the thermocouple at that end. If all heater zones show continuity then check the resistance of each zone and compare it to the value shown on your hot-runner. To correct either condition, turn the pilot adjustment screw slightly, as directed by the manufacturer. If the igniter has a pilot hole, move a sewing needle carefully around inside the hole to loosen any trapped material. With my old iron, I just cranked up the heat any time I felt like it wasnt hot enough. The plug fit better and held tighter, but still no temperature. Enjoy! A burned out or broken thermocouple should be replaced. It does not constitute professional advice. Thermocouples are designed to detect a pilot light's loss of heat and close the gas valve to prevent a gas leak. With any gas-fired appliance, if a strong smell of gas is present, do not try to relight the pilot or turn the appliance on, or turn any lights on or off. 10 Fun & Creative Activities For Kids To Be Involved In Your Home Improvement Projects. To replace a thermocouple: Step 1: Unscrew the copper lead and the connection nut inside the threaded connection to the gas line. But cleaning the device wont fix any technical issues. How to Survive an Encounter with an Ostrich, Unlock expert answers by supporting wikiHow, https://www.familyhandyman.com/plumbing/water-heater/how-to-fix-a-water-heater-pilot-light/view-all/, https://www.bobvila.com/articles/furnace-troubleshooting-2/, https://www.familyhandyman.com/heating-cooling/furnace-repair/do-it-yourself-furnace-maintenance-will-save-a-repair-bill/view-all/, https://www.familyhandyman.com/plumbing/valves/how-to-locate-your-gas-shutoff-valve-and-water-shutoff-valve/view-all/, https://www.familyhandyman.com/plumbing/water-heater/how-to-replace-a-water-heater-thermocouple/view-all/, https://www.sensorsmag.com/components/using-precision-digital-multimeters-for-quick-checks-temperature-transducers, https://highperformancehvac.com/how-test-thermocouple-multi-meter/, https://heatinghelp.com/systems-help-center/thermocouple-testing-procedure/. At the. The tube connects to the gas valve below the pilot light. Turn the gas back on and try the appliance. Now, remove the valve using pliers. If a thermocouple tests at 25 millivolts or lower, it doesnt have the power to keep a pilot lit and it should be replaced. If the thermocouple wiring is bare, missing insulation and is touch together anywhere between the sensing - probe end, and the connection points, the thermocouple will read at the area where the bare wiring is touching together. Yes, you can clean a thermocouple, but the task must be done with a light touch. Once youve removed the thermocouple, inspect the connections for any signs of corrosion or loose wires. Learn about the Maintenance and Handling of Thermocouples, Email: You can run into problems if you choose the wrong type of thermocouple . customerservice@temprel.com. Fireplace How To: Testing A Thermopile - YouTube 0:00 / 3:28 Fireplace How To: Testing A Thermopile Fire-Parts 2.52K subscribers Subscribe 1.3K 266K views 6 years ago For technical support, or if. An old toothbrush is a perfect tool for this job. Or you might catch an electrical fire on your appliance. On some gas valves opening the pilot valve may require turning and holding the gas valve control to the left or right. It didnt have a display, and Im not sure it even had a temperature sensor. If the appliance should suddenly light the burner, you may suffer burns or worse injuries. There are 9 references cited in this article, which can be found at the bottom of the page. To test the thermocouple, it must be hot. After that, generate heat on the thermocouple. To bypass the thermocouple: Move the tilts switch wire aside. Your igniter may or may not have a pilot hole. The pilot should heat the top 7/8" of the thermocouple with a clean (blue) flame. 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. Turn the appliance off. You'll learn how a thermocouple works and how to clean the thermocouple.Buy a universal thermocouple online: https://www.amresupply.com/catalog/Thermocouples-Thermopiles-662364-HV1GIf your pilot light keeps going out, or if your burner won't stay lit, then its best to clean the thermocouple first when troubleshooting. A few quick steps can have your gas appliance back in operation. Include your email address to get a message when this question is answered. The plug end was indeed shorted. I understand this seems quite confusing for you. I recently bought a new soldering iron, and have been familiarizing myself with it and learning what temperature it takes to do what. Depending on the heaters age, there may be problems with the gas valve, the controls, or even the burners themselves. Get free, zero-commitment quotes from pro contractors near you. You will need a wrench, multi-meter, and a flame source, like a candle or a lighter, to perform the test. I can solder wires with the fine tip just fine at 260 degrees celsius, but it takes about 300 degrees to do SMD parts. Once this check is done, turn the meter back to volts. The gas control thermostat will be on the outside of the gas tank, possibly on a nearby wall. Be cautious when reinstalling the thermocouple. If you have gas-fired appliances such as a water heater, space heater, or cookstove, these appliances may have one or more thermocouples. Most appliances hold the thermocouples in place with a spring clamp. When the flame is weak, boost up the flame to reach the device. I checked the internet, and found that a properly working K-type thermocouple will have pretty much no resistance when measured with an ohmmeter. If the thermocouple wiring is bare, missing insulation and is touch together anywhere between the sensing - probe end, and the connection points, the thermocouple will read at the area where the bare wiring is touching together. Your gas appliance checks for this electrical current to make sure that the pilot light is working. If it is mashed or one of the wires is broken off right at the thermocouple then youre going to have get a new one - that kind of thing cant be fixed. If the thermocouple doesn't function after cleaning it, it would be best to replace it with a new one. Gevorg Grigorian. Start the test by unscrewing the thermocouple from the gas valve. A correctly adjusted pilot flame is steady and blue, and stands between 1/4 and 1/2 inch high. If the flame goes out repeatedly, it may be getting too little air; if it's yellow at the tip, it's getting too much air. Take the two leads from the meter and touch themthe meter should read zero. Please copy/paste the following text to properly cite this HowStuffWorks.com article: Fix-It Club On his retirement, he started a remodeling and home repair business, which he ran for several years. It agrees to within a couple of degrees of the measured temperature on the soldering station when using the original tip so I figure the meter and the soldering station are at least somewhat accurately calibrated. Then, when the pilot is burning brightly, release the reset button. For a basic test, attempt to turn on the pilot light again. If it appears small and has an orange-yellow tinge, it may be too weak to heat the thermocouple. Just the fact that you have to shut down and replace a thermocouple means lost revenue. If it is short and blue, then it is too weak. In most cases, the thermocouple attaches to the gas valve with a thin copper tube. Were committed to providing the world with free how-to resources, and even $1 helps us in our mission. Experts suggest counting the voltage (v) in millivolts. When a thermocouple fails, the pilot light won't stay lighted. However, many people change them out about every four years. Like the other component parts in your furnace, the thermocouple can wear down over time, producing lower voltage than it should when heated. The thermocouple may get faulty if dirt builds upon and around it. This guide reviews how to replace a thermocouple to ensure gas appliances stay in good working order, as well as how to relight a pilot light. The Red wire is generally the negative (-) wire in thermocouples, harnesses, and cables. Make sure the connection is clean and dry. Remove The Thermocouple From The Pilot Assembly 05. Sounds interesting? A small electric current goes to the auto-igniter when the gas valve signals the gas to turn on. Set your voltage meter to read voltage (V) in millivolts. How to Remove the Thermocouple in a Heat & Glo Fireplace, Omega: Thermocouple: Different Types, What It Is, and How to Replace One, High Performance HVAC: How to Test a Thermocouple with a Multi-Meter. Richmond Water Heater Thermocouple Replacement: The How-To Steps 01. By signing up you are agreeing to receive emails according to our privacy policy. Here Ive shown a 5-step method to find out if your thermocouple is bad or not. Do You Need Emergency Furnace Repair? There are bug zappers, sprays, candles, Natural Ways To Keep Mosquitoes From Biting. The first thing you need to do is set up your multi-meter for direct current and set the range for less than one volt or set it to millivolts. A thermocouple is a device that produces a small electric current when it is heated. Ive been using the K-type thermocouple with my multimeter to measure the temperatures. Connection from the thermocouple to the valve. Next, take your meter and set it to ohms. Cleaning a thermocouple is not a fix for an issue, such as inaccurate readings. What does a thermocouple look like and how do you find it? 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. Gas appliance thermocouples have a standard design. Support wikiHow by document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); How to Fix a Thermocouple on a Water Heater? It is usually found near the system's pilot lights or burners. If you buy through links on our site, we may earn a commission. Just swap the two wires and itll be OK. A little poking around saved me a few bucks and a couple of weeks worth of waiting for a new thermocouple. On 2020-07-15 by Don Gilbert Remove the thermocouple by unscrewing the copper lead and connection nut (first) and then the bracket nuts. All information is subject to change at any time without notice. Thank you.". Caution: Some older appliances may not have a safety device to turn the gas off when the pilot is extinguished. A damaged heater can turn on the gas oven automatically. However, if you need a professional to do the job, you can pay $120 to $150. Answer: Unscrew the tilts switch wire. Save my name, email, and website in this browser for the next time I comment. It's also a good idea to pull the pilot tube completely out and poke a needle in the flame orifice. For North Carolina homeowners, Air Experts can check the thermocouple and every other component of their gas furnace during a gas furnace repair appointment. For more specific instructions on operating your multimeter, read the owners manual. First, lose the connection of that copper tube. Such as the gas heater, auto ignitor, and pilot light. It will secure your own safety. Put Everything Back Into Its Place 07. Start the test by unscrewing the thermocouple from the gas valve. How to know if a thermocouple is bad? A burned out or broken thermocouple should be replaced. If the reading is less than 25 millivolts, the thermocouple is bad and needs to be replaced. Selecting the Wrong Type of Thermocouple on the Transmitter. The desired voltage should be around 30 to 40 millivolts. The proper place for the device is in the flame of the pilot light. , it must be hot. Find the thermocouple, which is located next to the pilot light and looks like a small straight pipe. Hunker may earn compensation through affiliate links in this story. When a thermocouple fails in your control system, bad things happen. If your thermocouple is coated with a white, chalky material, this may indicate it's not functioning properly. I know this is the first question that hits your mind. Light green color, on a type K thermocouple indicates the occurrence of aging and a change in the chemical composition known as Green rot. The igniter is usually immediately adjacent to or at the edge of the burner. Contact us for complete details. And put off the thermocouple connector from the gas valve. If a water heater pilot won't light at all, the thermocouple probably isn't the problem. If the Leads on your thermocouple are reversed, the temperature measured will show to be varying in the opposite direction relative to ambient temperature. 30 July 2020. Your Promotional Selection Has Been Applied! Use an 8mm wrench to pull off the thermocouple. Who wants to get burnt or experience a shock? Step 3: Insert a new thermocouple into the hole in the bracket, steel tube facing up and copper lead down. A thermocouple lasts for an average of 10 years, and you need to replace yours if there is too much rust on it. 2 May 2006. Appliance Repair Expert. Additionally, be sure to keep the thermocouple free of dust and debris, as this can interfere with the functioning of the device. Ive seen quite a few appliances require turning and holding the valve to control. With it all reassembled, the meter was again showing the correct temperature. Sometimes you don't need to spend a single buck, and a little cleaning will do the trick for you. Do You Need to Hire an Electrician? It should be low, but definitely not a dead short. Step 2: Locate your thermocouple. Take the two leads from the meter and touch themthe meter should read zero. Locate the thermocouple on the gas control thermostat. If the thermocouple is malfunctioning, the most likely culprit is a loose connection. No wonder that it is also used in the water heater. Most of the gears set the thermocouple with a spring lamp. Install The New Thermocouple 06. To know if you have a bad thermocouple, set a multimeter to read millivolts and test the 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":"