Locate the pilot light controls on the gas valve. Carefully remove the faulty thermocouple from the gas appliance. Use a lighter or torch to hold a flame under this end. Remove the thermocouple by unscrewing the copper lead and connection nut (first) and then the bracket nuts. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. Touch the two leads together from the … But,It didn’t burn it up(only tested for a few seconds). Set the multimeter to read millivolts, then start the pilot and have your helper hold in the gas control knob to keep it burning. By using this service, some information may be shared with YouTube. Importantly, always make sure the tip of the thermocouple is directly in the pilot flame. The thermocouple is cylindrical and sits in the pilot flame; hence it will be the topmost of the pilot burner/thermocouple combination. Secondly, turn on the meter and set it to Ohms. If not then that could lead to problems. Everything is in alignment to the flame. Take the two leads from the … As the name itself suggests, this test is performed by placing the thermocouple … Put on meter lead directly on the gas valve side of the thermocouple. Gas valves cannot be repaired and in some municipalities require a licensed professional to install. Also make sure the tip of it is directly in the fire. Gevorg Grigorian. Gevorg holds a BS in Business Administration and Management from California State University-Northridge. Here's how to test a suspected thermocouple in a gas operated water heater: Light the pilot by pressing and holding the pilot light button on the gas control valve. BTW, it never exactly said what you wrote but may have implied it for those who lack common sense. When the heat hits the hot junction or tip of the thermocouple, it produces millivolts. 1 millivolt is equal to 1/1000 of a volt. Lastly, replace it. That is simply a test to check the meter for continuity. If the reading on the computer screen changes, this means that RFI is interacting with your wires since changing the EMF flux through the wire loop changes the voltage at the screw terminals. You need a new gas valve. 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. The tip of the thermocouple is called the hot junction and is where the two dissimilar metals join. Finally, Good luck! While all three are useful, the closed-circuit test will clearly indicate whether the thermocouple is performing … A yellow or orange flame means the system needs to be cleaned. They can troubleshoot the problems and replace the thermocouple if necessary. Before the test, turn off the gas supply because you must first remove the thermocouple. It’s function is to measure the oxygen level in the room. Let the Testing Begin!. My analog multi-meter cannot discern sub-unit readings, I need to get a digital one that does. The pilot light is controlled by a small box with black, red, or white dials. If you test the thermocouple with the multimeter and you get a reading above 25, then you have another issue. If it has an ODS as you describe then the place you are speaking of is likely too tight and does not allow enough infiltration air into the house or cabin or whatever to supply you with combustion air to burn the gas logs. While thermocouples use millivolts to determine the temperature, the millivolt reading will not be A thermocouple is a safety device for a standing pilot gas system. If the air or oxygen decreases the pilot becomes erratic and lifts off of the thermocouple or thermopile. Locate the gas tank, which is in the basement or lowest floor of your home. Include your email address to get a message when this question is answered. Remember, the meter should be set to DC voltage (might have to use the "Select Button"). So, the next question, “How to Test a Thermocouple with a MultiMeter”? The thermocouple was used to hold the pilot valve open. What is the thermocouple test procedure? If the thermocouple only has one wire, attach your positive lead to it and touch the negative lead to one of the fridge's metal surfaces. It is consuming too much air. Finally, NOW TURN THE METER TO VOLTS. you need to apply heat to the tip of the thermocouple to get a reading on your meter as explained in the article. This is a great option if you need help making the repairs or suspect your system has other problems, such as a faulty gas valve. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. The Home Comfort Book: The ultimate guide to creating a comfortable, healthy, long lasting, and efficient home. To check a thermocouple, you need a multimeter that is able to measure millivolts DC. Additionally, gas companies may add additional gases. So, back to the drawing board on making adjustments for altitude. my gas stops flowing to the pilot after a few minuets on my ventfree logs my flame is not lifting off of the thermocouple good voltage reading on thermocouple. They are available here. The three main tests used are the open circuit test, closed circuit test and resistance test. They are not the same. Your email address will not be published. How to test a thermocouple. Check for continuity by using a multimeter set up to measure ohms.Connect the multimeter test leads to the 2 thermocouple leads (polarity doesn’t matter for this test) and if the meter reads 0 or open circuit, then at least one of the thermocouple leads are broken. If you can't light the pilot, the problem most likely lies with the gas control valve or the gas flow itself, not the thermocouple. In the early 1900s, Honeywell applied it to the safety gas valve. 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. As an update, cold weather set in yesterday, I have been using the gas log fireplace more often, and running it hotter, than usual and since cleaning the pilot has begun to stay on more reliably. This further supports a thermopile issue. While all three are useful, the closed circuit test will clearly indicate whether the thermocouple performs properly under load and is often the primary test conducted. I am often asked about troubleshooting a thermocouple on gas systems. If you’re still unsure or don’t have a working pilot light, test the thermocouple with a multimeter. With over 13 years of experience, Gevorg specializes in residential and commercial appliance repairs as well as heating, ventilation, and air conditioning (HVAC) services. To test for this, please move your thermocouple wires around with a plastic pen. Check the thermocuple multimeter. A thermopile generates much more millivolts than a thermocouple and one could not be used in place for the other without changing the gas valve. % of people told us that this article helped them. This website uses cookies to improve your experience while you navigate through the website. A. You have to be careful when cleaning it. I have a furnace. We'll assume you're ok with this, but you can opt-out if you wish. Be cautious when reinstalling the thermocouple. If the pilot valve is closed the main valve would not open. To remove the thermocouple, chase the connecting wire (or sometimes it looks like a tube) back to the gas valve and use the appropriately sized open-end wrench (typically 3/8-inch) to unscrew the threaded end from the gas valve. Locate the pilot light controls on the gas valve. Okay, thanks for letting us know. Necessary cookies are absolutely essential for the website to function properly. Adjustments are made for higher altitudes. These links will lead to you purchase a product from another company. They are cheap enough. I suggest you use some sandpaper to remove the powder and see if that fixes the problem. This commission helps us pay for the overhead of running this website. We did add the following: *At sea level. Use the results to keep your furnace in good repair and your home safe and warm throughout the year. This causes corrosion problems sometimes. The tube connects to the gas valve below the pilot light. The pilot light is controlled by a small box with black, red, or white dials. Lots of resource and related links to help you learn more. If the pilot goes out, relight it and check the flame. Thermocouples. As you said, you put way too much voltage on it. Touch the two leads together from the meter, and … We also believe the products we link to help our site visitors find products they need to enhance or repair their HVAC equipment. It is likely a thermopile although there are some ventless gas logs that use thermocouples also. Solution 2 - To test this, unplug the thermocouple wire out of the controller (for a Mini or Micro Curing Controller, just unplug the thermocouple plug; for a Standard Curing Controller, unscrew the thermocouple wires from the terminal strip). This category only includes cookies that ensures basic functionalities and security features of the website. Thirdly, start the flame and put the tip of the thermocouple in the fire. Never use anything abrasive to do so as you could damage the thermopile or thermocouple. Ignite a lighter, or other heat source with a flame, at the opposite end of … In our area at 5600 ft our gas value is only 825 btu per cubic ft. They are as follows:1) Seebeck effect: The Seebeck effect states that when two different or unlike metals are joined together at two junctions, an electromotive force (emf) is generated at the two junctions. Obtain a volt meter and turn the dial to resistance ( Ω). Gas Heating Troubleshooting and Repair Index, How a Thermocouple Works | Thermocouple Testing Procedure Understanding, Conclusion | How to Test a Thermocouple with a MultiMeter, How to Change a Standing Pilot System to Electronic Ignition System, Changing a Standing Pilot Boiler to Electronic Ignition – Conversion Upgrade, Electronic Ignition Systems: Hot Surface Igniter, Honeywell Furnace Temperature Fan Limit Control, How to Test a Thermocouple with a Multi-Meter, Lighting a Pilot that is Electronic Ignition, Natural Gas Properties and Furnace Heating Efficiency, New Thermostat Problem or Gas Furnace Issue, How not to guess if the thermocouple is bad, Step by step procedure for testing a thermocouple with a multimeter. The thermocouple is a device made up of two dissimilar metals. Start the test by unscrewing the thermocouple from the gas valve. Closed Circuit Test. You are a freaking jerk. 30 July 2020. 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/, consider supporting our work with a contribution to wikiHow. Overtightening it can prevent the flame from lighting. Expert Interview. Your a buffoon. As long as the solenoid is energized, the pilot valve inside the gas valve remains open. The valve will stay open if I connect a AA battery(I know I am putting way too much voltage). If you haven’t done so make sure to test it as instructed on this page. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. While holding the meter leads in this position, light the pilot. Thanks to all authors for creating a page that has been read 32,151 times. The fireplace did, however, shut itself off (pilot stayed on) once. One probe of the meter should be connected to the copper sheath of the thermocouple … Therefore, if the pilot light was not lit or the thermocouple was bad, the main valve could not open. Altitude and gas value affect it. Is there any method to check this thermocouple with Digital |Multi Meter ? Appliance Repair Expert. Thank you.". Don’t you. Manufacturers/Contractors derate gas appliances in elevations over 2000 feet. These cookies will be stored in your browser only with your consent. This end appears needle-shaped and is designed to take on heat, so put the tip into the flame. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. ODS is an oxygen depletion sensor. Use the multimeter to take a reading of the resistance of the circuit. At this point I advise you to call in a professional to check things out. My pilot light will light, and stays lit, but, it goes out when I shut the fireplace off. Switch the settings to read millivolts, and then connect your meter's test leads to the wires of the thermocouple. I wouldn’t modify anything with a fossil fuel system especially something that is ventless. Valves are not repairable. You ask a friend, and the friend tells you the thermocouple is bad. That allows the main valve inside the gas valve to feed the main burners with gas. It will also have a metal pipe running into it, carrying the gas supply. That will help with a furnace thermocouple test. If the thermocouple is putting out 26 mV then something is wrong with the valve. To check the thermocouple, pick a sample. Choose a test to assess the thermocouple. How to test a thermocouple – The best instrument to use is a thermocouple thermometer as this will give you a temperature measurement rather than a voltage which will mean much less. Hold the knob in for 60 seconds, then release it. Because a thermocouple can measure large temperature ranges, you’ll find them being used in many different settings, such as in the steel industry and manufacturing plants. When the pilot is on, the fireplace turns on readily when I flip the wall switch. This website uses cookies to improve your experience. The amount of emf generated is different for different combinations of the metals.2) Peltier effect: As per the Peltier ef… The working principle of thermocouple is based on three effects, discovered by Seebeck, Peltier and Thomson. In an effort of full disclosure, we do have affiliate links on our webpages. Next, take your meter and set it to ohms. Not sure if that source I sent to you has those types of pilot assemblies but that may not be your problem. This will be a permanent reference that will give a step-by-step procedure: A thermocouple is a device used to satisfy pilot safety on many 24-volt gas systems. Gevorg Grigorian is an Appliance Repair Specialist and the Owner of G and R Appliance Repair in Los Angeles, California. Richard, How to Test a Thermocouple: 14 Steps (with Pictures) - wikiHow Save www.wikihow.com. If your thermocouple is coated with a white, chalky material, this may indicate it's not functioning properly. If the appliance has a thermocouple, the problem may be a faulty thermocouple. I’m sure you write a lot of helpful articles. By using our site, you agree to our. 14D0473. If the tip is in the flame, you have held the nob on the gas valve down for longer than a minute, the pilot flame is strong and steady, and the pilot still does not stay lit, then you likely have a problem with the gas valve. Thanks for the info. Locate the gas tank, which is in the basement or lowest floor of your home. These cookies do not store any personal information. There are 15 references cited in this article, which can be found at the bottom of the page. Lastly, Gas valves cannot be repaired as per any manufacturer. Your btu chart is not necessarily right. The three key measures used are the test of open circuit, the test of closed circuit and the test of resistance. Plumbers and HVAC service companies are skilled and knowledgeable with standing pilot gas systems. A thermocouples uses a sensor to measure the temperature of current passing through an object. Measure the current by using the multimeter device, set on millivolts. This guy writes a helpful article and makes one small mistake and you call him a idiot. It is typically shown as mVDC (might have to use the "Range Button") or is just the third decimal over on the DC voltage reading. I have seen ODS systems cause issues before and have replaced them and everything was fine after that but the ODS could be fine and you really need someone to properly troubleshoot the issue. If so then it is good. Currently it is out of order. Natural gas or even LP is not 100% pure and has a slight moisture content. This article has been viewed 32,151 times. So you have found the pilot light will not stay lit when you try to light the pilot light. Put the other lead on the copper line as shown by my right hand in the picture above. Sometimes when you try to light the pilot it does not want to stay lit. You know you have gas, and everything seems to be fine so what is the problem? Last Updated: December 23, 2020 Yes you should have a pilot adjustment try turning the pilot a little higher. Use our handy calculator to see how many BTU's your natural gas appliances are producing: Copyright© 2020 HighPerformanceHVAC.com |. Since this is gas and there is a possible safety issue if you feel uncomfortable doing this call a professional. What reading you should get if the thermocouple is good. The thermocouple is a simple, widely used component for measuring temperature. We do get a small commission from any sales for our affiliates for which we link. "Very clear and simple drawings make it easy to learn the basics in a short time. Hi. A thermocouple is a safety device that helps control the gas supply in gas-heated furnaces. We’ll see if the thermopile fixes the issue. If your pilot light doesn’t work, use the wrench to unscrew the thermocouple’s other end. Not sure I want to do that. wikiHow is where trusted research and expert knowledge come together. Place one probe on each of the wires and read the multimeter display. It is mandatory to procure user consent prior to running these cookies on your website. Connect the crocodile clips to the slots in the multimeter. With over 13 years of experience, Gevorg specializes in residential and commercial appliance repairs as well as heating, ventilation, and air conditioning (HVAC) services. We did have this addendum on our calculator when we published the calculator originally. The other part of the thermocouple tip is called the cold junction. I did know that I just didn’t take it into account when I made the tool. 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. A weld joins the two metals. The ODS system may be the problem. We use cookies to make wikiHow great. From the cold junction, a stem runs in length from the main body of the thermocouple tip to the gas valve. Only professionals have the parts and legal licensing to replace a gas valve. #eitechnician #checkthermocuple What is the thermocouple millivolt range for a good thermocouple? The thermocouple millivolt range should be above 25 millivolts. So how do you test the thermocouple to see if it is bad or not? MultiMeter Thermocouple Test Procedure First, remove the thermocouple. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. A standing pilot gas valve has two inner valves, one for the pilot light and one for the main valve. This is happening with increasing frequency. How to Test a Thermocouple: 14 Steps (with Pictures) - wikiHow Save www.wikihow.com. And you do know there is a difference between a thermopile and a thermocouple? Required fields are marked *. Place one of the test leads of the multimeter on the side of the thermocouple and the other to the end that enters the gas valve. The thermocouple consists of two wires that are joined together at one end (the "hot" junction). Thanks for proof reading and ensuring all our articles are idiot proof. How to Test a Thermocouple with a Multi-Meter step by step: Thermocouple fits securely in the pilot burner (pictured above). No, you need to find that particular part or one specifically for gas logs. Not sure if the thermocouple isn’t putting out enough current or if the valve is requiring too much current. without Turing on the flame or fire ? We also use third-party cookies that help us analyze and understand how you use this website. But opting out of some of these cookies may have an effect on your browsing experience. This is a common problem with thermocouples. How to Test a Thermocouple for a Water Heater – Everyone who has owned a gas heater including furnaces or water heaters will know that from to time you have to light the pilot light unless you have the electronic ignition that automatically lights the pilot light. {"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":"