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Lennox Pulse Furnace

devol Member Posts: 1
The furnace operated flawlessly on LP. Just converted to natural gas. Now it fires up but runs for only 10 minutes and shuts down. I have to recycle the power to get it to fire up again. It takes 2-3 times cycling before it starts again and runs again for only 10 minutes. Gas pressure OK, spark plug OK. Any help????


  • unclejohn
    unclejohn Member Posts: 1,833
    Why is it shutting down, hi limit flame fail?
  • Brp814
    Brp814 Member Posts: 22
    You mention the spark plug, but have you checked the flame sensor? Probably needs to be replaced.
  • JohnLappe
    JohnLappe Member Posts: 8
    Also make sure your intake and exhaust terminations are not blocked and check condensate drain, I worked on a lot of Pulse Furnaces and ran into these issues regularly, make sure you have the proper gas pressure also, when the furnace runs, is it smooth?
  • GW
    GW Member Posts: 4,618
    Kinda curious, Lennox got you the parts to convert that beast? This must be a friend or relative job!
    I'd start scoping the air switch, goo in condensate, measure micro amp on startup and see if it's different 9 minutes later, presure test the hx, change the flapper. Jump r w,
    If all that fails throw a new control at it. If that doesn't work, I'd start with a new furnace
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]