I'm getting a low volume hum in my house. It comes and goes. It's not
loud, but it is annoying. When it is humming, I can hear it all over the
house. I can also hear it in my attached unheated
garage. My wife can hear it also. I have been unable to pin point the
source. Anyone ever experience this? Any ideas what it can be?

Any correlation with furnace activity?

I've heard some irritating sounds from a high-efficiency furnace.
--
Pete Cresswell