I installed a couple of "quiet" bath fans, but although the air noise
is soft, the 60-cycle hum is quite loud. Very loud. Did I just get
poorly-made fans, or is there some trick to installation that is not
described in the instructions?

On Nov 22, 2:44 pm, hitch wrote:
I installed a couple of "quiet" bath fans, but although the air noise
is soft, the 60-cycle hum is quite loud. Very loud. Did I just get
poorly-made fans, or is there some trick to installation that is not
described in the instructions?

It could also be the way they are mounted to the ceiling joists
because it can transmit sound and vibrate. Try pushing up slightly on
the unit while its running and see if you hear any difference.