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dburell 12-29-2009 11:21 AM

Lennox Merit Series Furnace - Flame Sensor??
Hi everyone,

I've had this issue before, but had a repairman fix it. After I watched him, I realized how easily I could have cleaned the flame sensor on our furnace. I've noticed it's acting up again and would like to clean the flame sensor myself. SO, two questions:

It may seem simple enough, but how do I remove the top panel on the furnace??? The bottom panel lifts easily out, and the top panel has two metal gizmos on the top that I folded out, but can't seem to pull it down or out. Any ideas??

Once I get the panel off, where do I find the flame sensor?


dburell 12-29-2009 11:27 AM

Okay, I removed the top panel :)
I think I see the flame sensor on the bottom portion of the furnace anyway...a rod that's pointed down??

SPS-1 12-29-2009 05:39 PM

Not sure which way its pointed on your furnace, but I think they are typically secured with one screw, and have one wire coming off of it. Looks exactly like a steel rod, because thats exactly what it is. Some are bent, some are straight. When I researched this for my furnace, I found the suggestion to clean if with fine, gentle sand paper. Not sure why they suggested being so gentle with it ( its just a steel rod ), but I followed that suggestion, and it worked for me.
Only two words of caution:
1) turn off the power, of course
2) if you pull out a ceramic pretzel, that your ignitor, and you can break it just by looking at it wrong, so carefully put it back where you found it

beenthere 12-29-2009 08:13 PM

Sand paper is not good for a flame sensor rod.

While it is just a piece of metal. It has a coating to prevent pitting. And sand paper takes that coating off. And causes them to get dirty,corroded quicker.
Steel wool is what is to be used. Those green 3M pads work good are ok if you don't go over board.

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