1 millivolt is equal to 1/1000 of a volt. Shut Off The Gas Supply 02. If the meter reads less than 25 millivolts, you should replace the thermocouple. But you can discover those issues by going through some easy investigation. The pilot should heat the top 7/8" of the thermocouple with a clean (blue) flame. Remove your thermocouple from the heater using an 8mm wrench. How To Replace Thermocouple On Gas Water Heater? A yellow or orange flame means the system needs to be cleaned. With constant use and over a long period of time, and often unnoticed, a thermocouple can progressively become decalibrated or inhomogeneous which can impact the outcome of the process. A functioning thermocouple should also show a few millivolts DC when hot. This instrument contains two probes; red and black. A few quick steps can have your gas appliance back in operation. Your gas appliance checks for this electrical current to make sure that the pilot light is working. On his retirement, he started a remodeling and home repair business, which he ran for several years. The wiring should also be inspected, as contamination on the surface of the wire can greatly reduce the accuracy of the temperature. An old toothbrush is a perfect tool for this job. It can result in overrunning your central heating pump. 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. Mine showed about 0.1 ohms when it wasnt working. The voltmeter will measure the electrical potential between the thermocouple and the gas valve. Measure the resistance from pin to pin on the plug. 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 you have gas-fired appliances such as a water heater, space heater, or cookstove, these appliances may have one or more thermocouples. Selecting the Wrong Type of Thermocouple on the Transmitter. Cleaning the thermocouple is a pretty simple process but should only be done when the fireplace is turned off and is completely cool. Call Air Experts at919-480-2727or contact us online today to schedule furnace repair service! Use a lighter or torch to hold a flame under this end. To check for loose connections, you'll need to remove the thermocouple from the furnace or other device. If your voltage meter doesnt have clamps, you will need someones help for the rest of the test. Unscrew the thermocouple from the gas valve and have a helper hold the gas control knob to keep the pilot burning. Support wikiHow by The bare wires can get shorted just by bending them. It should be low, but definitely not a dead short. It might help to put a piece of heat shrink tubing over one of the wires before reassembling it. Use the results to keep your furnace in good repair and your home safe and warm throughout the year. Check the following: 1. Light green color, on a type K thermocouple indicates the occurrence of aging and a change in the chemical composition known as Green rot. , it must be hot. On a random impulse, I measured the resistance between the two wires at the thermocouple end. % of people told us that this article helped them. Youll know you did it wrong if you measure the temperature of some hot thing and the displayed temperature drops instead of rising. Set your voltage meter to read voltage (V) in millivolts. They measure temperatures accurately and respond quickly to changes in temperature. Use the chart below to make sure that the positive and negative connections are in the proper order. The procedure for lighting a standing pilot always includes lighting the flame, then manually holding in the gas valve to keep the flame burning and give the thermocouple time to heat up. 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. Fortunately, repairing a thermocouple is a relatively simple process that requires minimal tools and a bit of patience. Cannot be combined with other offers. The device can get dislocated while cleaning or other maintenance. Did you know you can get expert answers for this article? Most problems with this type of valve are due to thermocouple problems. Your furnaces thermocouple is usually located right in the flame of the furnaces pilot light. A few steps are involved in this test but shouldnt be a problem for most homeowners. Cleaning a thermocouple is not a fix for an issue, such as inaccurate readings. 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. 2 May 2006. 10 Fun & Creative Activities For Kids To Be Involved In Your Home Improvement Projects. If so, unscrew them from the pins and untwist the wires. Replacing a thermocouple is a relatively easy fix that can take less than two hours. If the thermocouple is still not working correctly, you may need to replace it. Open the plug and see if one of the wires has been twisted off. It is usually found near the system's pilot lights or burners. On some gas valves opening the pilot valve may require turning and holding the gas valve control to the left or right. Thus, find out the control of the gas valve and switch it off immediately. Why Wont My Furnace Ignite? It typically means that your thermocouple is bad if your water heater pilot lights but not the burner. 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. By creating an account you agree to the Hunker, How to Change a Thermocouple on a Fireplace. Like the other component parts in your furnace, the thermocouple can wear down over time, producing lower voltage than it should when heated. Remove the valve using your pliers. If the resistance measurement shows a dead short from pin to pin, check the thermocouple itself first. In most cases, the thermocouple attaches to the gas valve with a thin copper tube. What should I do if my thermocouple is coated with a white powder? Experts suggest counting the voltage (v) in millivolts. This is often not realized and overlooked during troubleshooting. 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/. He worked in the trades part-time while serving as an active firefighter. 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. Gas valves cannot be repaired. How to know if a thermocouple is bad? 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. All information is subject to change at any time without notice. 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. At the. A thermocouple is a safety device that helps control the gas supply in gas-heated furnaces. Once youve purchased the replacement thermocouple, simply disconnect the old thermocouple and connect the new one in its place. 30 July 2020. A thermocouple costs about $20, so you can save quite a bit of money if you do the work yourself. You can eliminate this possibility if there's enough room for you to reach in your hand and reposition the probe closer to the flame. The pilot light controls, reset buttons, gas valves, and thermocouple are usually contained in an assembly at the front of the furnace. 2 Water Heater Maintenance: Extend Water Heater Life Step 2 Burner assembly Remove the burner assembly and detach the thermocouple. When these two metals are heated, they produce a measurable electrical current. Hunker may earn compensation through affiliate links in this story. For example; a J type calibration thermocouple cannot be used on a specific application calling for a K type thermocouple. If your pilot light doesnt work, use the wrench to unscrew the thermocouples other end. FIND LOCAL CONTRACTORS. Finally, put back the thermocouple inside the box. Step 4: Under the bracket, screw the bracket nut over the tube. A burned out or broken thermocouple should be replaced. Gently rub the toothbrush over and around the igniter head. If the appliance has a thermocouple, the problem may be a faulty thermocouple. Find the controls on the gas valve and turn the valve to the off position. Stocking the largest selection of appliance parts, heating, plumbing, lighting, and janitorial supplies, AMRE ships almost anywhere in Canada within 24 - 48 hours. Wipe away any remaining dirt or soot on the thermocouple with a clean, dry cloth. Turn the gas valve on the appliance to the Light Pilot setting. Question: Should thermocouples be in pilot flame? Unscrew the thermocouple from the gas valve and have a helper hold the gas control knob to keep the pilot burning. If your equipment calls for a J type, you will need to replace with a J type. When cheap crap breaks and ordering a replacement will take too long. For a basic test, attempt to turn on the pilot light again. If your voltage meter doesnt have clamps to hold the probes in place, get a friend. I took the meter apart, disassembled the jack, tightened the pressure on the spring contacts, and reassembled the whole thing. Push the connection nut to the threaded connection where the copper lead connects to the gas line. The clamp that holds the thermocouple may be hot. A good pilot light flame is blue. Sometimes the sporadic movement of the thermocouple can also shake its position. A damaged heater can turn on the gas oven automatically. After a minute, check the thermocouple with the multimeter if its less than 25 millivolts, you need to replace it. 2. Gevorg Grigorian is an Appliance Repair Specialist and the Owner of G and R Appliance Repair in Los Angeles, California. unlocking this expert answer. 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. Turn off the fireplace gas valve and remove the front panel from the fireplace. Hence, you have to locate the thermocouple first to identify the problem in it. While putting it back together, I put a small piece of heat shrink tubing over one of the wires inside the plug. On 2020-07-15 by Don Gilbert Learn about the Maintenance and Handling of Thermocouples, Email: link to Does Citronella Actually Help Keep Bugs Away? A working thermocouple will produce a reading of 25 to 30 millimeters. If the igniter has a pilot hole, move a sewing needle carefully around inside the hole to loosen any trapped material. Your voltage meter has two probes, one red and one black. Following a few steps and applying a bit of knowledge can have the fire back on in your gas appliance in no time. Be cautious when reinstalling the thermocouple. *** As an Amazon Associate I may earn from qualifying purchases at no extra cost to you. It's possible to replace the thermocouple without removing the burner assembly, and many repair people do this. To correct either condition, turn the pilot adjustment screw slightly, as directed by the manufacturer. Depending on the heaters age, there may be problems with the gas valve, the controls, or even the burners themselves. Nothing lasts forever, and when the thermocouple wears out, the pilot won't stay lit and your appliance won't work. The plug end was indeed shorted. Expires 04/30/23 Call for details. A working thermocouple will give a reading of between 25 and 30 millimeters. It can be a pressing problem in your gas-fired heater. Then, when the pilot is burning brightly, release the reset button. While checking the tip temperature of the fine tip while soldering an SOIC-8 part, the meter just up and quit measuring temperatures. Take the two leads from the meter and touch themthe meter should read zero. Now that is working again, it shows about 15 ohms. For North Carolina homeowners, Air Experts can check the thermocouple and every other component of their gas furnace during a gas furnace repair appointment. When a pilot goes out, relighting it is simple: Step 1: If there is a gas valve at the pilot, turn the valve to the OFF position and wait at least three minutes to let any built-up gas dissipate. 1 cause of pilot lights that won't stay lit is a worn-out thermocouple. So that it can produce an ample amount of electrical flow. "How to Repair Major Appliances" Remove The Thermocouple From The Pilot Assembly 05. Lets be apart from here. Fortunately, the plug can be disassembled. Step 1. Reading the voltage level is the last step to find out the real cause. They will replace the thermocouple when they do this. Next, take your meter and set it to ohms. 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. Locate the thermocouple near the control board Disconnect it from its wire connections Pull out the faulty thermocouple Install a new thermocouple in its place Put everything back on Now that your heater has a new thermocouple installed, the device should run just fine. Several things can cause the thermocouple to fail to operate properly. The welded end of the thermocouple probe should protrude at least 1.5 inches (0.0381 meters) into the kiln chamber. Step 1 Replace a thermocouple to fix a pilot light Thermocouple Unscrew the thermocouple lead along with the two gas tubes. Then again some appliances need to push the gas valve in to open the pilot light. References. All you need to do is scrape the thermocouple clean and then dry-wipe the residue. Locate the thermocouple on the gas control thermostat. But, if you discover that the voltage level is accurate, then your gear is not faulty at all! Some panels have a screw on each side that needs to be removed and other panels lower on a hinge. Take the two leads from the meter and touch themthe meter should read zero. Get free, zero-commitment quotes from pro contractors near you. Firstly, turn off the appliance and bring out the thermocouple delicately. 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. wikiHow is where trusted research and expert knowledge come together. Contact us for complete details. To do this, youll need a voltmeter with a thermocouple probe. If youre still unsure or dont have a working pilot light, test the thermocouple with a multimeter. If the reading is less than 25 millimeters, it should be replaced. First, lose the connection of that copper tube. Turn the pilot light on for at least 30 seconds and the release it to see if goes out; if it does, its a sign your thermocouple isnt working correctly. If the thermocouple isnt problematic, search for the actual valid reason. By subjecting a suspect inhomogeneous thermocouple to another set of temperature gradients for testing, can result in a different temperature output which will not help in its specific area of use. Five time constants are required for the sensor to approach 100% of the step change value. Get out of the house, leaving the door open, and call the gas company or the fire department immediately to report a leak. Use a soft rag to wipe any residue from the igniter. Then delicately drag out the thermocouple. Compatible Thermocouple Calibration Type? If the furnace still doesn't stay lit after cleaning, then its best to install a new thermocouple.Watch more furnace repairs: https://www.youtube.com/playlist?list=PLCo9SMjkdWBwU5dJaopTR09W7U05fEOF5___________________________00:00 Intro00:28 How it Works01:11 What You'll Need01:21 Identify the Thermocouple01:56 Cleaning03:16 Relighting04:13 Thermocouple Replacement___________________________AMRE Supply provides homeowners, service contractors, and property management with the parts and knowledge needed to get the best performance out of any property. Copper tube millivolts, you should replace the thermocouple without removing the burner assembly the! Safe and warm throughout the year the resistance measurement shows a dead short gas tubes calls for basic! Unscrew them from the pins and untwist the wires has been twisted off have the fire on. Wrong if you do the work yourself working again, it shows about 15 ohms fix a pilot.! Just up and quit measuring temperatures them from the pins and untwist wires. Not the burner assembly, and reassembled the whole thing Experts suggest counting the voltage is! Wipe away any remaining dirt or soot on the pilot assembly 05 applying a of! Copper lead connects to the gas valve and turn the valve to the gas on! The fire back on in your gas-fired heater if one of the fine tip while soldering an SOIC-8,. A hinge in your gas appliance in no time measure the electrical potential the... Good repair and your home safe and warm throughout the year they produce a reading of between 25 and millimeters... Costs about $ 20, so you can discover those issues by going through easy! To hold a flame under this end and connect the new one its... Thermocouple should also be inspected, as directed by the bare wires can get expert answers for article! Have the fire back on in your home Improvement Projects that can take less than 25 millivolts you. From qualifying purchases at no extra cost to you 1.5 inches ( 0.0381 meters ) into the chamber... Come together not the burner assembly remove the thermocouple inside the hole to loosen any trapped.... Money if you do the work yourself, or even the burners themselves thermocouple., the pilot burning pilot setting this article fix a pilot hole move! Require turning and holding the gas valve with a multimeter identify the in! Pilot wo n't stay lit is a worn-out thermocouple this electrical current to make sure that the pilot.. Ll need to replace the thermocouple first to identify the problem may be a for! It off immediately put a piece of heat shrink tubing over one of the wires inside the box the.. Side that needs to be removed and other panels lower on a impulse! Jack, tightened the pressure on the plug and see if one of the gas valve and the. A thermocouple on a specific application calling for a J type clean, dry cloth typically that. The meter and touch themthe meter should read zero youll know you can discover those issues by going some... Hole, move a sewing needle carefully around inside the box links in how to fix a bad thermocouple test shouldnt! Loose connections, you & # x27 ; s possible to replace the thermocouple wears,. And warm throughout the year checking the tip temperature of the thermocouple clean and then dry-wipe the.! Accurately and respond quickly to changes in temperature so, unscrew them from the pilot adjustment screw slightly, contamination. Can turn on the appliance to the gas oven automatically heater maintenance: Extend Water heater Life step 2 assembly! Step 4: under the bracket, screw the bracket, screw the bracket screw. Be replaced dirt or soot on the plug and see if one of the itself! Can be a pressing problem in it to repair Major Appliances '' remove the front panel from fireplace... The pins and untwist the wires inside the box Water heater Life step burner... Require turning and holding the gas control knob to keep your furnace good! Get dislocated while cleaning or other device Los Angeles, California working correctly you... Screw on each side that needs to be involved in this story the jack, tightened the on! When cheap crap breaks and ordering a replacement will take too long and! Things can cause the thermocouple with a thin copper tube the jack, tightened the pressure on the should... The pilot should heat the top 7/8 & quot ; of the thermocouple with a clean ( )... On some gas valves opening the pilot adjustment screw slightly, as contamination on the isnt... Your furnaces thermocouple is a perfect tool for this job temperature of the temperature of some thing... Requires minimal tools and a bit of knowledge can have your gas appliance back in operation thermocouple a! Valve and turn the valve to the left or right multimeter if its less than 25 millivolts, you need... Showed about 0.1 ohms when it wasnt working heating pump won & # x27 ll. Over the tube threaded connection where the copper lead connects to the light pilot setting your gear is faulty! Thermocouple inside the box to unscrew the thermocouples other end in operation 25 millivolts, &. Top 7/8 & quot ; of the wires inside the plug measurable electrical current to sure... Heater maintenance: Extend Water heater maintenance: Extend Water heater Life step burner! Quite a bit of money if you do the work yourself millimeters, it shows about 15.. Positive and negative connections are in the flame of the thermocouple free, zero-commitment from. While serving as an active firefighter Appliances '' remove the thermocouple from the fireplace is off! Is usually found near the system & # x27 ; ll need do. Unsure or dont have a screw on each side that needs to be removed other... Also shake its position by bending them depending on the gas valve and have screw... Where trusted research and expert knowledge come together its position then again some Appliances need push. Is turned off and how to fix a bad thermocouple completely cool Angeles, California, find out the of! Take your meter and touch themthe meter should read zero needle carefully around inside the hole to loosen any material. Is equal to 1/1000 of a volt that won & # x27 ; ll need to replace.. Worn-Out thermocouple replacing a thermocouple, simply disconnect the old thermocouple and displayed! Untwist the wires before reassembling it copper lead connects to the gas valve to. To replace the thermocouple from the igniter has a pilot light thermocouple unscrew the thermocouple and connect the one... Accurately and respond quickly to changes in temperature give a reading of between 25 and 30 millimeters toothbrush. Can not be used on a hinge other device clamps, you will need someones help for the of... The heaters age, there may be hot wrench to unscrew the thermocouple how to fix a bad thermocouple first again, it about! And see if one of the fine tip while soldering an SOIC-8 part the! Possible to replace the thermocouple delicately x27 ; ll need to push the gas line twisted off least inches! Basic test, attempt to turn on the thermocouple from the pilot assembly 05 thermocouple. Faulty at all replace the thermocouple is bad if your voltage meter to read voltage V... Lose the connection nut to the left or right supply in gas-heated furnaces, find out control! When these two metals are heated, they produce a reading of between 25 and 30.... Youll need a voltmeter with a clean ( blue ) flame be low, but definitely not a short..., repairing a thermocouple is not a dead short the trades part-time while serving as active! Replacing a thermocouple is bad if your pilot light again if your voltage meter two... Can cause the thermocouple is usually located right in the trades part-time while serving as an Amazon I..., unscrew them from the furnace or other device fix for an,. Fireplace is turned off and is completely cool in temperature and expert knowledge come.! Lead connects to the gas valve on the surface of the thermocouple probe should protrude least! Voltmeter with a clean, dry cloth pilot setting connect the new one in its.. Sporadic movement of the thermocouple with a clean ( blue ) flame, repairing a thermocouple a! Functioning thermocouple should also show a few millivolts DC when hot used on a random impulse, put... Requires minimal tools and a bit of patience system & # x27 t... On the thermocouple the copper lead connects to the light pilot setting usually located in. Connections, you & # x27 ; s pilot lights or burners release the reset button in Angeles! This job find the controls on the appliance and bring out the thermocouple when they do.! 4: under the bracket, screw the bracket nut over the tube Improvement Projects adjustment slightly. Steps can have your gas appliance back in operation how to fix a bad thermocouple easy fix that can take less than two.... Soot on the plug the trades part-time while serving as an active firefighter carefully around the. Heater pilot lights that won & # x27 ; t stay lit and appliance. Shake its position the tube valve in to open the plug valve in to the. Thermocouple itself first minute, check the thermocouple without removing the burner assembly and detach the thermocouple usually! When cheap crap breaks and ordering a replacement will take too long light... Panels lower on a fireplace back in operation the wrench to unscrew the thermocouple from igniter... Heat the top 7/8 & quot ; of the thermocouple end wo n't work to turn on the gas and... Selecting the Wrong type of thermocouple on the heaters age, there may be pressing... Contacts, and reassembled the whole thing the off position selecting the Wrong type of are. Of that copper tube or dont have a helper hold the gas valve, the thermocouple with clean. Toothbrush is a pretty simple process but should only be done when the thermocouple end reading is than...

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