Cleaning a Flame Sensor

Posted by Mark Bower on

There are many issues that arise with furnaces and sometimes they are easy fixes, other times they require time and a lot of patience. If you’re finding your gas furnace is intermittent or simply not working, try this simple fix first to see if it takes care of your problem.

Your flame sensor can sometimes be the cause of the furnace not working. If your booster assembly comes on, your ignitor glows and your burner turns on but only for a few seconds, it is most likely your flame sensor. On most newer furnaces, your control board will flash a code telling you the flame sensor is weak. It’s a simple fix and only takes minutes to clean and hopefully get your furnace back to heating your home again. First, you will typically find your flame sensor where you would see flames coming from inside your furnace. It will mostly likely be attached to the burner assembly or at the burner. It is commonly found to be anywhere from 3.5” to 7” long and has a ceramic or porcelain handle and a small metal rod at the end. Be very careful when removing the flame sensor, if you damage any part of the burner assembly, you may not be able to replace the burner assembly with a new one as most are no longer available.

To clean your flame sensor you will need a piece of steel wool. Gently clean the metal rod at the end with very little pressure. Do not use an abrasive material such as sand paper! Sand paper is too coarse for the delicate metal and could result in damaging of the sensor. If the sensor is damaged your will have to purchase a new one. Once you’ve run the steel wool over the sensor a few times, replace all parts back into the furnace and try turning on your furnace again.

If you are finding that you are cleaning the flame sensor several times a season it could be possible that your furnace is not getting enough outside fresh air.

This may not be a complete solution to your furnace problems, but it is a good start. If this does not remedy your situation please make sure there are no flashing error codes on your control board. If you are requiring further help after trying this, please be sure to have the following information available before calling us: Model Number, any flashing error codes and their meaning, and how far your furnace gets before it no longer works.

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