I just had my roof replaced and part of that had a powered roof vent/fan installed. It has made a difference already in the upstairs temperature, BUT--it was extremely noisy; the vibration and hum were heard & felt throughout the upstairs and in one bedroom it was intolerable.

So the contractor came out & replaced it (after 3 phone calls over 3 weeks to him) and the new one is much quieter, but still the hum is quite noticable and somewhat annoying in that one bedroom.

So, how much noise is usual & acceptable from one of these power vents? I am wondering if there should be a sound absorbing gasket of sorts that perhaps was not installed, or is it just a case of a low end unit that makes more noise than a more expensive one would, or is it quite typical to hear a noticable hum from the roof vent through the ceiling? BTW, there is an attic with two layers of batt insulation under the roof.