11:47AM | 01/28/05
Member Since: 09/23/03
22 lifetime posts
I have a Lennox G51MP furnace. Just built this house last year and the furnace was installed in November, 3 months ago.

Last night, it was 0 degrees out. When my wife woke up me for work, she said "its feezing". When I went down stairs, the thermostat said 51. The furnace obviously shut off in the middle of the night. And, my wife babysits a 3 month old everymorning.

Luckily, I put a set of gas logs in when I built my house, so I quickly got them burning and within an hour the living room was toasty. However the basement is freezing as well as the upstairs.

I got out my manual from lennox and read the trouble shooting guide.

When the furnace first comes on, both the Red and Green LEDs blink fast, which the manual indicates as normal operation.

It goes through this cycle and then attempts to light... You see the pilot light come on, then a flame, then the flame goes out.

It does this seeral times for about 3-4 minutes then finally shuts down altogether.

Now, A different code come up. Alternating slow flashing red and green. The manua indicates the follwing.

"Watchguard-Burners failed to ignite, limit open longer than 3 minutes, or flame sense lost 5 times in one heating cycle."

Can anybody tell me what I need to do to fix it????

Is there a part that is malfunctioning?

Please, if you know the cause of this, give me some advice.

My furnace guy is out of town until monday.




11:27AM | 01/29/05
Member Since: 12/19/04
62 lifetime posts
If your lucky and it isn't a failed electronic part you can check a couple of things. Make sure your vent pipe an dintake pipe are clear. The drain hose is not kinked and then turn the switch off at the furnace and tighten any connections that you see inside the furnace. Just repaired my brothers furnace two nights ago and it was loose connections on a relay.

Good luck and stay warm.



04:49PM | 01/29/05
Member Since: 12/16/04
54 lifetime posts
Either a bad flame sensor, or bad connection at the flame sensor. Make sure you have a good ground to the unit and you may check the polarity to the furnace, sometimes the ignition control will work with reversed polarity until the flame starts, then the electrical curent flows through the sensor improperly and flame rectification does not occur.
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