Lennox Don't Work In The Cold

Discussion in 'Energy' started by bwilson4web, Dec 24, 2022.

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  1. bwilson4web

    bwilson4web Well-Known Member Subscriber

    With temperatures below 10 F (-12 C), the house heater, a high efficiency Lennox SLP98UH110XV60C stopped working around 10 AM. Calls to the local Lennox dealers revealed they are booked up until after Christmas. A grim Christmas future.

    The installation manual was with the unit and I soon found the error code, E228 meant the pressure sensor indicates a blocked flue or air intake pipe:
    [​IMG]

    Since our pine trees have been shedding needles, I got on the roof but no problem found:
    [​IMG]
    I have a fear of heights and did this solo.

    The pressure sensor was failing. YouTube videos confirmed the diagnosis.
    [​IMG]

    Using a jumper, the failure occurs during the "calibration" startup:
    • Calibration starts - pressure switch OPEN
    • Combustion and flue fan starts a stepped speed up - pressure switch eventually CLOSE during speed steps. So I applied a jumper to substitute for the failing switch
    • Flue fan backs off to initial speed - pressure switch OPEN, remove jumper
    • Flue fan speeds up to the step when jumper installed
    • Furnace continues to operate adding ~8 F per hour. The TV room measured 40 F at 8:00 PM and now shows 65 F at 11:30 PM and heater is still running.

    [​IMG]

    At this lower fan speed, the heating is reduced. This allows the furnace to operate just a little faster than the heat loss from the outside cold. I've set the thermostat to a high temperature to extend the house warming. So far, it is working. But eventually the furnace will warm up the house enough to turn off heating.

    After a time delay, the calibration cycle will restart but fail because of the static jumper. Calibration must start with the switch OPEN and then close during the combustion fan speed step. Disconnect when the fan goes to idle and back ON when it steps up.

    LATER THAT NIGHT

    At 5:30 AM, we just had a power outage. The automatic emergency generator came on 30-45 seconds later and I restarted the furnace.
    [​IMG]

    Lights, power, and heat …. neat.

    Bob Wilson
     
    Last edited: Dec 24, 2022
    Domenick likes this.
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  3. Glad you figured it out and kept the house from freezing. Merry Christmas to you and yours, Bob.
    We're further south than you and hitting 20 F, but luckily heat is working ok. We are keep a decent stream of water flowing from all the taps and spigots, because our pipes are in the attic and if they were to freeze and break it would pretty much be a disaster.
     
  4. Stay safe and stay warm. Merry Christmas
     
  5. bwilson4web

    bwilson4web Well-Known Member Subscriber

    On Christmas Eve, I was able to order a rebuild kit, $75. I have no delivery expectations but we're OK for now. Just I can't leave the house for more than a few hours.

    Bob Wilson
     
  6. bwilson4web

    bwilson4web Well-Known Member Subscriber

    I made a YouTube with detailed comments about what to do:


    Bob Wilson
     
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  8. bwilson4web

    bwilson4web Well-Known Member Subscriber

    The replacement part arrived. After removing the plug protector pins and moving the mounting bracket to the other side, it went together and works!

    Bob Wilson
     
    R P likes this.

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