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gas furnace is keeping us cold

laurieo Member Posts: 3
I have been having problems with my gas furnace for a couple of weeks. I have it set at 70, and it will come on and work correctly from 1-3 days. Then all of a sudden, I hear it turn on, I hear the flame ignite, then nothing. It just runs and runs and runs, with no lowing and no heat. What is wrong with it?? This only started after I changed our filter last month. Thankfully it has been pretty nice here and that we have electric heaters in a couple of rooms. Thanks for the help.


  • Techman
    Techman Member Posts: 2,144
    no heat?

    How does the heat come back on? Make? Mn#? What efficiency is the furnace? I'm assuming here , the furnace starts ,the indoor blower runs an you get cold. You heard the sound of the gas flame or the sound of a inducer fan motor supplying /exhausting air for the fire ?
  • laurieo
    laurieo Member Posts: 3
    getting colder here in montana

    All I know is that it is a Lennox and was installed in the mid 1990s. When it is working correctly, it turns itself on and off. When it starts acting up, I have to keep trying to get it to work again by turning it on, waiting to see if the heat starts blowing out of the vents, and if it does I leave it alone to do its thing. If not, I turn it back off at the thermostat. Nothing seems to blow after the sound of the flame being lite. It just continues to run, without blowing, until I turn it off. I am not sure about the other info that you asked for, as my furnace is in the basement and I am unable to get down there by myself. The furnace room is under the dining room, which is where the thermostat is, which is how I can hear what is being done by the furnace. Just in case it matters, it all seemed  to start when I changed my furnace filter last month. The person that inspected it a couple of years ago said that it was a higher quality furnace and was at 80%, whatever that means. Hope this helps.
  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    You need to have

    someone come take a look at it who is a professional. It sounds like the burner is not lighting every time so it could be any number of things wrong. The fact that it is intermittent may mean it just needs a pilot cleaned or a flame rod checked.
  • laurieo
    laurieo Member Posts: 3
    furnace tech was an idiot...lol

    I did have someone come, but because it happened to be working correctly at the time, they said that there was nothing that they could do. And he charged me for this tidbit of info. Well I will try again with someone else. Just hard to get anyone here, in no mans land. Thank you for your time and help.
  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    Try contacting

    Lennox at 800-953-6669 and ask for a local Lennox service company. Make sure you have Model and Serial number of the unit.
  • John Mills_5
    John Mills_5 Member Posts: 946

    Very frustrating for tech & HO to not have a unit act up when we are there. Know a model #? Probably  G16 if 80% and a Pulse if 90% (vented with 2 white pipes). They work totally differently. The 80% would have a draft inducer start first. Once the draft is proven by a pressure switch, the spark ignition should light the pilot. Once the pilot flame is proven, the main burners should light and the soon after, the fan comes on. Hopefully the tech cleaned the pilot and flame sensor as that is usually the culprit of problems.

    Anyway, next time it quits, go to it, turn off the switch on the side and back on again. Look through the louvers or take the louvered door off and watch it. See if you can tell at what point it goes no further. This would be a big help in a tech's diagnosing it.

    The original company should come back with no trip charge if it acts up more, at least we would.
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