The ceiling hvac register in my bedroom is noisy. The noise is
primarily broad band "whishing" from the air over the blades of the
damper and diffuser. If I remove the register, the duct is very quiet.
Are there quiet diffuser/registers out there? I just replaced the
register with one that has individual curved blades which helped a bit.
The damper portion is wide open and only contributes to noise making.
Are there diffusers withoug dampers? Would it be advisable to dampen
the line closer to the attic AC unit? Or getting a professional to
reduce the fan speed?
The room also has a return vent. Of course, it also is a noise maker.
I was able to stop the high frequency singing by "tuning" the grill
Thanks for the reply, Edwin.
The register has two controls: an inside damper which I have wide open
and outside diffuser blades which are adjusted to make the air flow
parallel to the ceiling. I read that this was best for efficiency.
Maybe I will try to remove the damper blades.
Air Noise comes from turbulance, it would stand to reason that the act of
diffusing causes turbulance and therefore noise.
If you want a quieter register you want one that allows for smooth airflow.
You still want a damper bacause a wide open vent means that vents elsewhere
in the house will have reduced airflow. The damper allows you to balance
the air to each room.
You could also add an air filter to the register which would slow and mix
the air before the diffuser reducing noise in that stage, it may result in
slightly reduced airflow but you said noise was a problem not trying to hog
the A/C for your room. Check the other rooms as well. If a register is
closed somewhere, you might be getting too much air at your location.
A larger register will also help by allowing the same volume of air to exit
a larger area, the velosity of the air over the diffuser will be reduced
which will reduce noise as well.
I have had this problems in several houses: An unbalanced airflow system.
Too much air is coming from this outlet, leaving airflow in others too slow.
In one house, where all registers whistled, I rewired the fan down to the
low setting and that fixed it. In other houses I just stuck a towel or
fiberglass insulation in the duct behind the register, reducing the airflow.
Probably have everyone jump on me for this, but it worked fine.
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