I have 3 ND dampers in my system. One for each floor. They come ot out the plenum as 1st floor (16x10), 2nd (16x10) and 3rd (12x12) on prgressing sides. When the first floor calls for heat (which isn't a lot due to a wood stove) everything runs with minimal noise. When the 2nd floor calls it starts out fine but then the 3rd floor damper starts vibrating making a noise like hive of bees. When the 3rd runs there are no extraneous sounds in the others.
We never have this in the summer when the AC runs. Right now I've blocked the 3rd floor off. Any help to alleviate this?
ND damper vibration noise
Re: ND damper vibration noise
Sounds like the vibration might be due to airflow changes when the dampers adjust. A possible fix could be adding some sort of damper noise isolator or even adjusting the air pressure. If you're not already, you might want to check the balance of the system—sometimes slight adjustments to dampers can help reduce those vibrations. It could also be worth inspecting the ducts for any loose or uninsulated spots that could amplify the sound.