The obvious answer, of course is that they do not know the Words. But this guy wasn't satisfied. "Must be harmonics" he said. "do you Think that a snubber could work?"
"OK, so it is a heated floor?" I asked.
It is a heated floor. With a thin resistive foil, no dimmer no thermostats. Just DOL, 230 V 50 Hz. The foil is covered with an insulating layer somewhere between 3 and 6 mm thick. And on top of that the floor as such. The foor hums so that people cannot sleep in the room where the floor is.
My take on this is that there is an electrostatic attraction between resistive foil and insulating layer (with an epsilon around 5). Force is voltage squared, so the dominating frequency should be 100 Hz. So far, Everything computes.
But this has never happened before. Anywhere. At least not in this guy's experience. And he works a lot with heated floors. Question: Do floors hum a lot? Or is this one a rare exception?
If they do hum - what do you do to silence them?
Half full - Half empty? I don't mind. It's what in it that counts.