Most gas furnaces use either a flame sensor or a thermocouple often referred to as a "thermal coupler". Both are safety devices that sense the presence of a flame and control the flow of gas to the appliance accordingly. If no flame is present, the sensor stops or prevents the flow of gas from the gas valve, thus preventing the dangerous situation of gas flowing into the appliance when there is no flame to burn it.
Flame sensors and thermocouples are simple parts that wear out and fail over time, and most are easy to replace. The tip of the thermocouple is positioned in the flame, keeping the tip heated at all times. If the pilot flame goes out, the tip cools, and the thermocouple automatically shuts off the furnace's gas valve.
These units have electronic igniters that light the gas for the burners, while the flame sensor makes sure the burners have lighted successfully. If there's a problem with ignition and the burners fail to light, the flame sensor shuts off the gas to the burners.
Honeywell, White Rodgers, and other manufacturers make universal replacement thermocouples, usually with 30 millivolt ssl plugins crack ratings for standing-pilot furnaces.
The length you see on the package, such as 24 or 30 inches, is the length of the thermocouple's lead, which is the flexible metal wire between the fitting end that attaches to the gas valve, and the thermocouple tip that sits in the pilot flame inside the furnace.
Electronic flame sensors are much less universal, and you must find the exact part for your furnace model. Shop online through appliance parts dealers and compare their prices to those at local distributors. If you need a part in a hurry, find a local dealer who has the part in stock. Here are the basic steps for replacing a furnace thermocouple. Always follow the manufacturer's instructions specific to your model:.
Here are the basic steps for replacing a flame sensor. What Thermocouples and Flame Sensors Do. Continue to 2 of 5 below. Difference Between a Thermocouple and a Flame Sensor. Continue to 3 of 5 below. Purchasing a Replacement Thermocouple or Flame Sensor.Furnace Maintenance: How to Maintain Your Furnace
Continue to 4 of 5 below. Replacing a Thermocouple. Always follow the manufacturer's instructions specific to your model: Shut off the gas and electrical power to the furnace. Remove the furnace's access cover. Unscrew the nut that holds the thermocouple end fitting into the gas control valve, using an open-end wrench. Loosen the nut s and remove the thermocouple. Straighten the lead on the new thermocouple, and shape it to resemble the old thermocouple.
This doesn't have to be precise; it just helps to start with a similar shape. Connect the new thermocouple to the pilot burner assembly bracket, tightening the nut s just snug; be careful not to overtighten. Thread the end fitting into the gas control valve, and tighten it by hand. Turn on the gas and electrical power to the furnace. Replace the furnace access cover. Continue to 5 of 5 below.
Replacing an Electronic Flame Sensor. If the furnace has been running, wait 30 minutes for the flame sensor to cool completely. If the sensor is integral to the gas ignition system, call a professional furnace technician for help.
Disconnect the electrical wire leads to the sensor. Disconnect the other end of the leads at the control box.
Remove the flame sensor by loosening the fastening screw s with a nut driver or wrench.Flame sensors help to ensure the security and practicality of your equipment when building heaters, furnaces, and a range of other products. A small and effective sensor designed to detect and respond dynamically to the presence of flames or fires, flame detectors offer instant responses to heat that can include the sounding of an alarm, the deactivation of a fuel line, and even the activation of fire suppression systems.
Regardless of what your next project entails, you can rest assured that you'll find the parts and service you need here at Furnace Part Source. Not only do we havedifferent products to choose from, including flame sensors, control modules, and ignition plates, but we also provide the highest quality customer support around too.
How to Find & Clean a Flame Sensor in a Lennox Furnace
At Furnace Part Source, we only source the best possible flame sensor equipment, from the most reliable manufacturers, from flame sensor wires to electrode assemblies, to various pilot assemblies and flame sensor parts. Here, you'll find products from Lennox, Heil, Fenwal, Carrier, and many other big-name brands, along with international postage and same-day shopping. Browse through our extensive catalog today to find the solutions for your next project, or contact us to see how we can help!
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Flame Sensors Flame sensors help to ensure the security and practicality of your equipment when building heaters, furnaces, and a range of other products. Select sub-category. Amana Goodman F Flame Sensor. Add To Cart. Fenwal Electrode Assembly, Part Heil QuakerFlame Sensor, Part Honeywell QA Flame Sensor. ICP Flame Sensor. Lennox 69w43 Flame Sensor. Lennox 79J22 Flame Sensor. Lennox Flame Sensor Part 12F Lennox Flame Sensor Part 18G Lennox Flame Sensor Part 20J Lennox Flame Sensor Part 39F Lennox Flame Sensor Part 43K Lennox Flame Sensor Part 51M Lenox Flame Sensor Part 31L Nordyne Flame Sensor, Part Rheem FLame Sensor.
Rheem Flame Sensor. Rheem Flame Sensor, Part If you have a furnace flame sensor in your heating furnace, you may need to replace it. Sometimes these sensors stop working properly, causing your furnace to cut out every few minutes. It can be very annoying. If you have determined that your flame sensor is causing your furnace to malfunction, then removing it and installing another is the solution to this problem.
Replacing the flame sensor on a furnace is not a difficult task. With some basic home-improvement, skills you should be able to complete this task within an hour or two. Follow these steps to replace your furnace flame sensor. First find the flame sensor inside your furnace.
Make sure that all heating is turned off and cannot travel into the furnace. Open the top using your screwdriver. You should be able to see a small L-shaped device which is hanging from the pilot burner, and with connections to the gas or electric circuits. This L-shape is the part that you need remove.
You may have to remove the whole pilot burner set in order to access the flame sensor. Once you have found your flame sensor and examined it, purchase a replacement. Unlike ignition mechanisms, the flame sensor will need to have an exact part. Universal alternatives are not suitable for this device. Remember that it controls turning the heat off when the furnace reaches the correct temperature, so any malfunction in the sensor could cause the furnace to overheat. Once the furnace has been turned off, wait at least half an hour before touching the flame sensor.
That is because it gets hot, and will be extremely dangerous to touch before this cooling period. The sensor may be permanently attached to the ignition system, in which case you will have to remove the lot. It may also be attached via a screw. You should remove the wire leads connected to the sensor, then remove the screws using your screwdriver or a wrench. Place the new sensor in position by the pilot ignition system. Your sensor should be facing the correct way, and have a clear view of the pilot light.
When it is in the right position, tighten the screw. You can then add the connecting electrical leads to the sensor, and attach the leads back to the electrical control box. If you had to remove the ignition, replace it now. You should then screw the access cover back down, and turn the electricity back on.
We welcome your comments and suggestions.Skip to main content Flame Sensor for Furnace. In Stock. This is a flame sensor. It senses the flame of my gas furnace. The original one was over 20 years old. It stopped working so I had to get this new one. Even though my furnace is not a Goodman, it uses this same part.
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Add to cart. Had flash code 2 - no flame lockout. Extended the life of old sensor by cleaning the electrode with steel wool when waiting for the new one.
Replacing it with his one is a more permanent repair. So the Carrier furnaces sometimes go through these during the heating season. I've had problems before, and cleaned the sensors late at night in the winter to get the heat working again furnace won't start when one of these fails or needs to be cleaned.
I ordered one of these as a back up to keep in the house. It helps me sleep better. Ferguson Industries F Sensor.
Only 20 left in stock - order soon. The old flame sensor was getting unreliable, swapped out with this one and it's worked perfectly since. Perfect fit with both the sensor and the plug. Flame Sensor. Our old flame sensor we had to keep cleaning it to get it to work properly. I am very happy with this sensor works perfect and couldn't beat the price. Now the heat works fine instead of kicking on and off which should save us some money on our gas bills. Nothing fancy here, but I am happy to say that the flame sensor ceramics and metal end up sending the right signals whatever those may be to my RUUD natural gas furnace.
I tried cleaning my old one, but that didn't work, so I purchased this one on Amazon. It works great and has not sent a false signal yet. Cheap and very easy to replace yourself. Nordyne Flame Sensor. Not too much to say about it. It is a flame sensor. Arrived as described. Works great. Carrier LH Flame Sensor. It is a part that I needed for my furnace. Reasonably priced.
It's one of those items that needs to be used for a length of time in order to fully evaluate it. Time will tell.The furnace comes with many components to analyze. Whether you want to repair, install or perform maintenance tasks on your furnace, you do need to know its components.
One of those components is the flame sensor. Although the word flame goes hand in hand with furnace, the word sensor may throw you off a bit. I can simplify this a bit for you. As with any major appliance, safety features are always important. The same thing goes for a furnace. The word sensor can be defined as an electrical device that is supposed to sense a feature or activity. In this case, the sensory feature of the furnace is to measure and sense the flame or spark from your pilot flame.
The way it works is simple. The whole process is an ignition sequence. Think of it as a chain reaction. It begins as the igniter or spark ignites the gas to create the flame. This current has to be on the proper level to function. The furnace will come with a control board that measures this reading once the ignition process starts.
If the control board does not read the correct level of electrical current, the furnace will cut off the fuel intake to prevent an explosion or fire. This is what makes the flame sensor so important. Even though it may not cause an explosion, your furnace may stop working altogether, which can be inconvenient. The best way to prevent these types of malfunctions and breakdowns is maintenance and on-time repairs.
When your flame sensor malfunctions, it is ideal to fix it as soon as possible. You may find many reasons why a flame sensor is not working. The first reason can be a dirty flame sensor. As with any mechanical part, you should always keep it clean for optimal performance.
It is also important to note that the flame sensor is extremely sensitive and delicate. Therefore, any type of dust could affect its performance. Carbon buildup can also cause a faulty sensor. However, if you always keep your flame sensor clean, it could just be that the sensor has gone bad. In this case, you can try to replace the flame sensor yourself.
As a safety precaution, you can replace and install a new flame sensor every two to three years. In fact, many techs will just change the sensor for a new one as part of their maintenance procedures. One symptom of a bad flame sensors is the ignition, which has already been discussed. If the furnace does light but shuts down immediately, this would indicate a flame sensor issue.
Make sure that you also look at the porcelain on the sensor. If it is cracked, you could be dealing with a broken flame sensor. The first thing you should check that you have is the necessary equipment.If the flame sensor is bent or warped, you can obtain a new one directly from Lennox or from an appliance parts store.
Do not use sandpaper to clean the flame sensor rod. Cleaning the flame sensor with sandpaper can make it more difficult for the component to successfully sense the flame. Lennox gas furnaces contain an important safety component known as a flame sensor. As long as the component senses the flame, it sends a message to the main furnace control board telling it to keep the main burner on and the gas valve open. If the flame sensor can't sense the flame because it's too dirty, the furnace may shut itself off.
Finding and cleaning the flame sensor in a Lennox furnace is a simple repair that takes just minutes. Flip the circuit breaker switch that corresponds to your Lennox furnace to the "Off" position.
Lift the access panel on the front of the furnace straight up to clear the tabs on the bottom of the furnace cabinet. Set the remove panel aside. Note that some Lennox furnace models require you to remove two side screws to free the front access panel. Look for a thin metal rod on the left side of the burner assembly; this is the flame sensor. Remove the screw that holds the flame sensor rod in place. Scrub the flame sensor with steel wool to remove any grimy build-up.
Wipe the sensor with a clean tissue before replacing it to remove any remaining residue. Replace the front access panel. Flip the corresponding circuit breaker switch back to the "On" position to restore power to the furnace.
Megan Mattingly-Arthur has been writing professionally since Hunker may earn compensation through affiliate links in this story. Tip If the flame sensor is bent or warped, you can obtain a new one directly from Lennox or from an appliance parts store.
How to Replace a Furnace Thermocouple or Electronic Flame Sensor
Warning Do not use sandpaper to clean the flame sensor rod. Step 1 Flip the circuit breaker switch that corresponds to your Lennox furnace to the "Off" position. Step 2 Lift the access panel on the front of the furnace straight up to clear the tabs on the bottom of the furnace cabinet.
Step 3 Look for a thin metal rod on the left side of the burner assembly; this is the flame sensor. Step 4 Scrub the flame sensor with steel wool to remove any grimy build-up.
How to Tell If Flame Sensor is Bad
Step 5 Replace the front access panel. Share this article. Megan Mattingly-Arthur. Show Comments.This part does exactly what it says — senses flame to ensure the furnace has fired. It will leak out of the furnace and into your home where it can easily explode when a water heater fires up or a gas stove lights.
To locate the flame sensor, you will need to remove the furnace access cover. It might be held in place by tabs and slots, knobs or a few screws. The porcelain insulates the sensor against grounding itself on the metal furnace frame. Some sensors are straight; some have a degree or degree bend near the end. The sensor is mounted to the outside of the burner assembly. It has a single wire attached to it.
The flame sensor protrudes into an open fire chamber or through the housing into the interior where the flame is burning. The finer the grit the better. Fine-grit emery cloth has a higher number than coarse or medium. The reason to use fine grit is to avoid the grooves in the soft metal of the flame sensor that coarse emery cloth can cause.
Grooves collect carbon from the burner flames. As carbon builds up, the sensor will fail again and require cleaning. This video shows how to remove the sensor and clean it with emery cloth. Take the part with you along with the furnace information. The brand, serial number and model number can be found inside the access panel.
A call to the supplier is the quickest way to get the right part, or you might be able to find it by searching the site using the make and model of the furnace.
Universal sensors are available too.
They are available at your local Home Depot, Menards or other building supply store. This quick and easy repair works most of the time when your furnace has the most common symptom — starting and then shutting down within a few seconds. Your best bet is calling a certified HVAC repair company to determine the cause of your furnace malfunction. Local Pro: Cost of Furnace Flame Sensor Replacement.