Rerurn to Romy the Cat's Site

Romy,
You maybe thinking of your a/c problem backwards.

In use, air conditioning vents become louder as the air speed and turbulence increase.
Reducing the aperture of a vent can increase noise because a reduced aperture increases air flow speed and turbulence (venturi principle).

You want somewhat more airflow but SLOWER air speed
You do NOT want a more powerful air pressure blowing harder and faster.

To get this you want to:
1 - use a more open vent style or
2 - remove the vent grill entirely or
3 - replace with larger vents or
4 - install additional vents without increasing the ducting attached to the primary manifold. You would have to divide the existing ducting or a use a small secondary manifold near the listening room vents. (This assumes the cooling of the listening room is now adequate and only a small increase in airflow is necessary if any – of course a long hot summer could alter your current appraisal).

Adding an extra duct/vent connected to the primary manifold would alter the relative cooling to the listening room without slowing down the airflow speed at the vents (although it would slightly reduce the air pressure on all vents in the house)

As a test, try removing the vent grills in your listening room, you should get more airflow with less noise. If this produces an improvement than going to larger or additional vents would be suggested.

About your kitchen a/c noise,
Some of these thoughts apply to your noisy kitchen ventilation.

Also, I would not be surprised if your kitchen a/c had a shorter and straighter duct than other rooms in your house. Air friction through the duct is increased by the length and bending of the duct. The vents in your house supplied by shorter and straighter ducts may have a stronger output than desired and are closed down producing more noise while vents with longer and more serpentine ducts are opened fully and produce less noise.

You could also reduce the kitchen vent noise by adding a larger or additional vent along with a duct constriction closer to the primary manifold. This would preserve the airflow and move the noise closer to the manifold where it is partially baffled by the ducting.

Adding an additional length of ducting and snaking the superfluous duct around would increase the noise reducing effect of the duct.

An a/c contractor probably has a bag of tricks for these modest problems and changes. Be glad that the sound and vibration from the a/c ventilation fan is not a problem – that is a more serious issue in terms of annoyance and remedy.

About your ceiling fans,
If you wish to increase the air circulation but not the basic a/c cooling in your listening room you are going to need better ceiling fans than the ones you described. Increasing air circulation is what ceiling fans do and work well and quietly doing.

Your ceiling fans should always become quieter as they are used at slower speeds (less vibration and air turbulence). If they don’t work that way, you are most likely hearing the groaning sound of the electric motors used at a speed they don’t like and not fan noise itself. You should rarely or barely hear a good ceiling fan in operation at slower speeds. They make a considerable improvement in summer cooling comfort and also in redistributing warm air in winter when they are barely moving.

Regards,
Robert

Rerurn to Romy the Cat's Site