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Furnace buzzing - WoodCzech - 03-17-2023

Last night whet it was quiet in the house I heard faint buzzing.  Electrical 60Hz like a transformer.  I tracked it to the heat register and subsequently all the way to the gas furnace.  The buzzing was coming from inside it.  Not loud, had to put my ear to it to hear it.  Then suddenly it stopped about 10 minutes later.  I don't remember hearing it before and haven't heard it since.  The furnace works fine.

Any clue?  Anything I should worry about and check?

RE: Furnace buzzing - EatenByLimestone - 03-18-2023

Furnace humidifier?

RE: Furnace buzzing - fredhargis - 03-19-2023

My guess is you have a coil going bad, they are in contactors to switch something on/off and they will buzz when they start to fail. My experience (and it's not a lot) os the buzzing gets really bad before they fail...they don't just stop working. But I'd still want it fixed, though if it's not making noise you may have to wait for it to get worse. Re read my first few words, this is a guess, maybe Roly or Blackhat has an idea.

RE: Furnace buzzing - Snipe Hunter - 03-19-2023

I situations like this... I send Blackhat a PM

RE: Furnace buzzing - blackhat - 03-19-2023

Get the doors off the furnace and run it through a couple cycles. You may have to hold in a fan door interlock switch to make it work or tape the switch down. There is a 24v transformer and it’s the likeliest culprit. Touch the transformer body. Warm is normal, hot is not. There may be a second transformer to drive a humidifier or an ignition transformer to drive spark ignition. Likely not a sign of immediate failure but pending failure is possible. Let me know what you find.