Noticed a noise similar to an electric alarm clock buzzer, coming from my furnace(it's old but I can't replace it yet). It sounded like the solenoid that opens the valve was going bad so I checked the net and other people seam to have the same thing. So I replaced the the B/I valve, it fired right up and about an hour and a half it started buzzing again so I checked the voltage from the transformer, 10.9 volts(not 24) so ok it's the trans, replaced that, same thing, I am sure the sound is coming from the valve it's self used a mechanic's stethoscope to trace the sound. It seems like it's got a piezio buzzer inside, it runs fine for a while and then buzz.... any ideas?
thanks Father Time