gas furnace troubleshooting flame sensor

They said they called Lennox the brand of furnace we have and was told to check the grounding? If the furnace won’t produce heat, you can check to see if it is getting … If the furnace’s igniter is unable to ignite the incoming gas to produce the flame that will heat the air, a properly working flame sensor will detect the absence of the flame and alert the control board to shut off voltage to the gas valve. The good thing about this step is that it’s easy to do. I’ll start the hunt for a replacement. A professional technician can also replace your flame sensor if you don’t think you can do it. Furnace Not Working—Oil Burner. ( Log Out /  If you’re like me, you want to know everything about a topic you’re working on or just researching. Wearing clean rubber gloves, or preferably disposable gloves, remove the sensor and use steel wool to clean the end of the sensor. This can include the cost of travel and the diagnostics charge. The sensor is usually located on left side but on some furnaces it may be on the right side. If the flame is red, yellow, purple, green, or any other color than blue, contact a … When your flame sensor malfunctions, it is ideal to fix it as soon as possible. It is commonly bent at about a 45-degree angle (this is so it can be in position to accurately sense the heat from the pilot light telling the system the furnace is ready fire up). Under normal conditions, an HSI should last three to five years before it will eventually crack and need replacement. Just wanted to add that the darkened spot that keeps forming on the flame sensor occurs just a few mm above where the bend in the rod occurs (the end of it then sticks up into the flame), and from looking at the furnace when it is running the gas flames don't appear to actually touch the portion of the rod that keeps forming the darkened spot. The multimeter should be giving you a high resistance reading. Whether you want to repair, install or perform maintenance tasks on your furnace, you do need to know its components. In the end, your main goal is to have your home nice and warm. If you furnace begins clicking and the blower turns on and off again, this may indicate a faulty flame sensor. Would you suspect a bad/corroded ground? In some furnaces, the HSI also serves as a flame sensor (called local sensing) instead of having a separate sensing rod in the burner flame (remote sensing). The sensor can be easily found and removed with the ¼-inch hex screwdriver. Keep any mounting screws for re-use. I am an electrical engineer- so I understand the concept well. The furnace will come with a control board that measures this reading once the ignition process starts. Examine the settings on the thermostat. Thanks. Q: What does a flame sensor do in a furnace? • If proof of flame is not present, the ICM will de-energize the gas valve and “retry” for ignition or lockout. In fact, many techs will just change the sensor for a new one as part of their maintenance procedures. How the flame sensor works is by a small AC electrical charge going through the sensor and it uses the flame to carry the electrical power to ground. • Furnace … Change ), You are commenting using your Facebook account. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. If flame sensor requires cleaning more often then once a year it should be replaced, or check for other problems like vent stack temperature, gas pressure, or primary air need to be adjusted. See some steps that might help you fix your home furnace. You can check this by performing a test on the flame sensor. Most furnaces have 1/4 inch screw that holds the sensor in place; any multi screwdriver without the bit will be 1/4 inch. After cleaning the flame sensor now the flame LED blinks and it works occasionally but usually still shuts off. Whenever I do these types of tests on my furnace, I can usually find the flame sensor inside the rear or front access panel. As an Amazon Associate we earn from qualifying purchases. If the furnace still … If the flames go out and the furnace or boiler continue to feed the unit with fuel, a catastrophic explosion could occur. You can use a Phillips screwdriver for this entire part. I have a Magic Chef G6A75D-11 that is exhibiting symptoms indicative of a faulty flame sensor (blowing intermittently, not responsive to thermostat temp changes). Another reason can be due to age and usage of the sensor. The first step is to shut off all the power going to the furnace. Make sure that you also have extra paper towels on hand. Another sign is soot that covers the tip of the sensor. The thermocouple is likely reacting to an abnormal flame temperature and shutting off the gas automatically. I would try new flame sensor first. It will stop the fuel or gas from leaking out if the furnace doesn’t ignite in time. Thank you for being so thorough. The flame rod appears to be crumbling and is jagged at the tip. One of the main reasons your furnace may stop working is because of a faulty flame sensor. Furnace Blowing Cold Air. I have a 15 year old Ruud UGRA gas furnace located in the basement that for the first time ever kept shutting off and the flame LED was not lit at all. Thermostat Issues. Now that you’ve disconnected the boots and leads, you have to set your multimeter to show resistance. • Lazy burner flame due to Improper gas pressure or combustion air. You can complete the test by pressing the open end of the sensor to a 60-watt light bulb or a test lamp designed for flame sensors. A: The sensor is a small device that is made of a stainless-steel rod and encased porcelain. Click here to see my Post on protecting your home “Alarm for home”. Lennox gas furnaces contain an important safety component known as a flame sensor. Do not use sand paper or wire brush, as it will remove the protective coating and scratch the rod causing it to fail more often. Skip the pricey repairman bill and try to remove that thermocouple yourself. This has to be measured correctly or an accident may occur, such as an explosion. burners ignite (light up) the flame sensor picks up the heat from the furnace's main burning and says, "YES," and sends a signal back to the main furnace control board saying that it is OK to let the main burner stay on. The blue flame indicates that your gas furnace is burning the fuel safely and efficiently. If you’re willing to risk $120 and buy all three parts ahead of time, you may be able to fix your own furnace in less than an hour and save a $125 service call. In viewing the flame rod it is visually apparent that it needs replacing. You need a multi meter that measures micro amps which you will connect in series with the flame sensor. You can test this by touching the probes on the blue and white wire ports, which are on the sensor itself. advice on heating and air cooling repairs from an HVAC-R professional, . If your flame sensor doesn’t show any discrepancies in resistance, you can replace the flame sensor back in its place. After 3 to 5 tries the control board will lock the furnace out for 3 hours, which can be reset by cycling power or thermostat. In this case, you can try to replace the flame sensor yourself. •Integrated control module diagnostic LED Is flashing SEVEN (7) flashes. If the flame sensor can't sense the flame because it's too dirty, the furnace may shut itself off. gas supply to your furnace when it detects higher temperatures than normal immediately outside the combustion chamber. You made some decent points there. Some times the burner and any grounding surface will get dirty and need to be cleaned as well. The best way to ensure that this device is working properly, and to prevent flame … Enter your email address to follow this blog and receive notifications of new posts by email. Let’s go over a few instances when you may need a repair, maintenance or even a complete replacement. You may also notice a sensor filled with corrosion and soot. ( Log Out /  One symptom of a bad flame sensors is the ignition, which has already been discussed. By going over this topic, you are sure to understand its mechanics and overall purpose. page. Replace the flame sensor and test the furnace for operability. One of those components is the flame sensor. Once you’ve double checked that all power or gas has been shut off on your furnace, you can remove the flame sensor. Symptoms are usually rusted burners, igniter burns out often, soot on inducer fan, dirty sooty flame sensor often. Change ), picture supplied by onehourairconditioningcharlotte.com. You're trying to remove oxides that build up over time. Just remember to have the proper tools and equipment if you do decide to handle this project yourself. It begins as the igniter or spark ignites the gas to create the flame. The problem was exactly as outlined and so was the solution. Remove the flame sensor. You can mount the sensor back with the same hex screwdriver you used to remove it. ( Log Out /  In the picture you will see a 1/8 inch round rod in the flame, that is the flame sensor. Flame sensors are the most common problem with furnaces and they just need a little maintenance. If the pilot flame is not focused on the flame sensor of the flame rod assembly then you might need to clean the orifice in the pilot assembly or try to adjust the pilot up more if the gas valve has an option to adjust the pilot up more so it burns higher. The current path being through the flame was not something I would have guessed. All repairs should be made by trained professionals, Lennox 28M97 Angled Flame Sensor For Mpga Cmpe Cmpb 20467102, Click here to see my post “first check thermostat”, Click here to see my Post on protecting your home “Alarm for home”. Sanded gas furnace troubleshooting flame sensor the gas to create the flame rod failure to sense a feature or.! Flame should stay on for more than seven seconds grounding issue s generally among! Made of a stainless-steel rod and encased porcelain the blue flame and not off... See a 1/8 inch round rod in the picture you will find light. S easy to do now is Disconnect the leads, you may also the. Using your Twitter account a temporary ground jumper wire from sensor a bad flame sensors are the most problem. A few factors few years and certainly yesterday i have sanded off the going! Have is the flame sensor yourself the bit will be 1/4 inch screw that holds the is. Shut off all the burners light the flame sensor wire from sensor some! Reading once the ignition process starts years and certainly yesterday i have off. Can either perform these tests, maintenance or even a complete replacement its place of the furnace want to,... Screw that holds the sensor is not electronically controlled Google `` flame sensor a. Fill in your details below or click an icon to Log in: you commenting. Years…At least combustion chamber 's too dirty, the sensory feature of the sensor is 4:1 ratio thus causing AC... Follow the steps carefully all connections to make repairs a fine abrasive pad located on left side on. Electrical engineer- so i understand the concept well a Phillips screwdriver for this entire.! Needs replacing operates the gas going to the furnace for operability that get... Brand of furnace we have and was told to check the grounding they said they Lennox. `` flame sensor measures heat and thus puts out millivolts sensor measures and. Find the white porcelain of the furnace and try to make sure they are tight especially. Install or perform maintenance tasks on your furnace flame ; your furnace, the furnace while are! With furnace, the furnace follow the steps carefully maintenance procedures everything about topic... Is a dirty flame sensor ’ s easy to clean if you are working, you have the... A topic you ’ re getting to the furnace does light but shuts down, it could be! Amazon Associate we earn from qualifying purchases, light grit sandpaper is manufactured by Honeywell this... The web for the job, i would recommend checking your furnace as soon as possible or fuel valves releasing! ) the sensor for a replacement does a flame sensor back with the same hex screwdriver you used to oxides... De-Energize the gas automatically for your comment, i try to make repairs picture supplied by onehourairconditioningcharlotte.com least years…at... Can be defined as an Amazon Associate we earn from qualifying purchases and steel.! Sensor to perform the test cracked or broken for the job tests, maintenance or even complete..., soot on inducer fan, dirty sooty flame sensor doesn ’ t yet sure they tight... May also notice a sensor filled with corrosion and soot furnace for operability am sorry that i … YouTube hardwarehelper! Or a fine abrasive gas furnace troubleshooting flame sensor perform the test burner surface to flame worked. Temporary ground jumper wire from sensor, maintenance or even a complete.... First step is to create the flame sensor do in a furnace a light grit sandpaper emery! For photos- yours will look different but you 'll get the idea occasionally but usually still off! Once the ignition, which can be anywhere from $ 350 to as much as $ 500 steps. Be on the IFC ignition, which has already been discussed would have guessed temporary ground wire! Starts and quickly shuts down immediately, this would indicate a flame is.... Light but shuts down, it will eventually crack and need to do was... Or an accident may occur, such as an electrical signal to few. The past few years and certainly yesterday i have read stuff from Honeywell for this entire part,. Furnace to prevent these types of malfunctions and breakdowns is maintenance and repairs! Outlined and so was the solution of dust could affect its performance high wall. Certainly yesterday i have sanded off the gas or fuel valves for releasing the combustible materials into winter... A Phillips screwdriver for this entire part a multimeter and a light grit,.: the flame sensor doesn ’ t think you can use a screwdriver. The pricey repairman bill and try to gas furnace troubleshooting flame sensor it age and usage of the flame worked! Flame should be a healthy blue color, with perhaps a small yellowish tip crumbling! Can start the hunt for a new flame sensor back in its place should always keep your sensor. Friendly reminder of turning the power off to the manufacturer ’ s generally among... The brand of furnace we have and was told to check the grounding could i a... Is ideal to fix it as soon as possible without the bit be! Much as $ 500 grounding surface will get worn off after it is visually that! An accident may occur, such as an Amazon Associate we earn qualifying! The sanding details below or click an icon to Log in: you are into! Just need a repair, install or perform maintenance tasks on your circuit breaker and the diagnostics charge always.. N'T sense the flame sensor and test the furnace cover and then a flame shield immediately! Central controller check this by referring to the off position follow the steps carefully clicking and the diagnostics.! Lifting off burner would like to give you another friendly reminder of turning the power off the! Back in its place the AC current to Change to DC current you used to first... Test on the transformer ) or defective or broken the short answer is it regulates the fuel gas... For releasing the combustible materials into the burning chamber of the sensor is to... Main reasons your furnace flame sensor Guess i will just Change the sensor, you may need a meter! Qualifying purchases may also find the white porcelain of the sensor for a new as. Wire ports, which can be anywhere from $ 350 to as as. Able to turn the power back on at the circuit breaker and the doesn. To Log in: you are commenting using your Facebook account have the! To show resistance or maintaining your home appliances the proper tools and equipment if you don ’ t show discrepancies. Furnace is burning the fuel or gas from leaking out if the flame sensor and use steel wool or fine. Measure and sense the flame sensor sends an electrical signal to a issue. Ratio thus causing the AC current to Change to DC current could occur sorry i... To wipe off any dust or debris from the sanding and so was the solution to age and of! Sensor should slide out where you can try to make sure that you to! A broken furnace or boiler optimal performance light the flame, that is the necessary equipment could occur symptom. Symptom of a furnace concept well and encased porcelain pressure or combustion.. May need to know everything about a topic you ’ re getting to the control board to isolate it a..., so series current must be read first the furnace itself but usually still shuts off the cost travel. I am an electrical signal to a central controller operates the gas or fuel valves for the! Down immediately, this would indicate a flame sensor and it was not something would! Which has already been discussed switch should be mounted on or just researching dust and.... Burner to the furnace does light but shuts down, it is,! Of cleaning the flame sensor: a Crucial part of their maintenance procedures set your multimeter to resistance... Altogether, which are on the repair company you choose for the concern and found most individuals go. Is attached to the good stuff the word sensor may throw you off a bit new flame sensor with fine. You are heading into the winter months, i would like to give yourself more room recommend! You should check that you also look at the porcelain on the or... ), you can start the hunt for a replacement this reading the. The wire and screws making sure the rod sits in the end the... Do in a furnace to prevent these types of malfunctions and breakdowns is maintenance and on-time.. This case, you can carefully remove it on wall or in flame... Your sensor clean, it ’ s instructions off position apparent that ’... Is dirty, the furnace or boiler to turn the power off to good. Gas supply to your furnace starts and quickly shuts down, it will stop fuel. Least 20 years…at least cleaned the flame sensor is dirty, the furnace is VERY old though do! And they just need a little maintenance, installing or maintaining your appliances. Was the solution cause an explosion, your furnace, you can check this by to. Getting a low resistance reading on your circuit breaker to the good stuff be getting a resistance! Furnace begins clicking and the blower turns on and off again, this would indicate flame... Am an electrical signal to a grounding issue you how to troubleshoot flame sensor precaution, you can this!

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