Wrath of the Flame Sensor
February 1, 2008 – 8:15 amA few years ago I paid a maintenance guy 75 bucks to come out to my house and tell me that the reason the heat wasn’t running was due to a dirty flame sensor. He took the sensor out of the furnace, whipped it on his pants, and put it back in. The problem was solved.
I came home last night to a house freezing at 55 degrees. Our dogs weren’t very happy with me. From the sounds of the furnace I knew it was the same sensor problem. I cursed.
I had two options: call the guy again to have him come out, give me a dirty look, and wipe the sensor on his pants again or just do it myself. I chose the latter.
First off, the flame sensor is not an easy thing to get to. I had to remove a security faceplate, which by definition, is not something I felt qualified to do. Once the plate was moved I had to locate the little bugger. It’s a tiny stick about 2 inches long and the width of a toothpick. It’s also located behind the pilot light (which was off BTW) in a space that was just large enough to get my hand into. After all the futzing to find it I took a pencil and used the eraser end to “clean” the sensor. I spent 10 minutes or so erasing what I thought was dirt of the sensor. I honestly couldn’t tell if I was actually removing dirt. It was still black when I gave up and put everything back together.
To my astonishment though, when the furnace fired back up the igniting problem had been solved. The furnace now started up in under 10 seconds. At the worst, the furnace would attempt to start for a minute, finally stop, and fall into failure mode.
So by cleaning off this magic toothpick my house is back to a balmy 70 degrees.