Sick Lennox Furnace (PLEASE HELP)

John_147

Because the furnace ran fine for weeks after he replaced the sensor he says it isn't a problem with his work. Which I almost tend to believe, we had some cold weather in those weeks during which the furnace ran without trouble.

John_147

Sick Lennox Furnace (PLEASE HELP)

I have a WhisperHeat by Lennox furnace (model number G20Q3E-50-2) that is approximately 15 years old. I had trouble the pilot lighting but the main burners never lighting. A furnace guy checked and found the flame sensor to be rusted and the porcelain portion to have cracks, so he replaced the sensor.

The furnace was fine for about three weeks. Now, the pilot will light, the main burners will light and run for a few seconds (usually around 4-12 seconds) then go out. For a few days if I would turn the power off and back on it would repeat the problem but eventually continue to run and ehat the house. Now I can't get it to run and it is down to 57 degrees in the house. And I don't have the money the money to have a service man come out again.

Any help would be greatly appreciated.

[Deleted User]

Why not call the first guy back...

Doesn't seem like he got the problem solved...

Robert O'Brien

So

Why don't you call him? If I were him I'd be very inclined to work with someone who's as honest as you seem to be,particularly 2 days before Christmas

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S Ebels

John

First, tell us where you are located. Maybe one of us is nearby and can lend a more personal hand.

Second, Assuming that the furnace will still light the pilot, then light main burner, and go out after a few seconds........correct? I'd suspect that the problem is still in the flame sensor circuit somewhere. Grounding can be a real issue for that part of the furnace control. I would check the terminals on the flame sensor wire, at both ends to see if there's any corrosion or rust evident. If so scuff it off with some emery, a nail file, whatever you have handy and try that. Also check the wire itself. It will run from the flame sensor in the burner compt. down to the main control on the furnace.

s.brown

Yes, I agree about the flame signal wire. Grounding is very important.You should also be certain that the door to the burners has been replaced properly as well because if it isn't then there could be an intermittent problem with getting your 24 volts consistently

dana_3

sick furnace

there is a switch on the left side on the burner door, as the door swings open it then sends power to the contol to lite the pilot. the flame sensor signal back to the control should be around 4vdc. if then all else is good, replace the control board

Empire_2

Without reading the previous posts,

What I would have done is of course replaced the sensor due to the crack. Next, which is mandatory the pilot burner or it's orifice HAS to be cleaned. Seems like few do this and just attack the obvious. Also, as a last note I tell my guy's that I want them to write a story on the work order so I know what you saw, how you corrected it and any opinions as to what they think may happen in the future.:-)

When I get, NO HEAT replace flame sensor, everything OK. I want manifold pressure and all the obvious report's. I don't think that is asking to much.

Bottom line was the pilot orifice cleaned and adjusted if necessary?

Merry Christmas......................

Mike T.

Empire_2

Dana?

Do you mean DC micro amps? I think that's what you meant.:-)

Mike T.

John_147

I am located in Southeastern Wi.

I have checked the connections at each end of the wire and the terminals are clean, and tight fitting. I also looked at the length of the wire and don't see any evident damage to the wire or insulation.

John_147

I don't think the orifice was cleaned. How do you recommend cleaning it?

Charles G.

Pilot light

Best way to clean the pilot light is to call the original service tech back and say, "Please clean the pilot light. And while you're at it, FIX THE FURNACE."

Rich W

Have you done any drywall, painting or staining work in the house recently. Any "stuff/dust" in the air can contaminate the sensor-even if the pilot is clean. All of the other things mentioned should be checked as well. There could be an intermittent problem with the control that only happens during extended run times...LOTS of things can go wrong. Even with a relatively simple furnace like this.