Heat Pump Noise

[GDM]

I am working with a classroom building that has individual heatpumps mounted in the ceilings of each classroom. These heat pumps are very loud and disrupt the professors when they are operating. Does anyone have any experience in using sound insulation for heat pumps? If so, do you have any ideas on the best way to insulate the heatpumps for sound dampening? Would it be better to insulate the compressor, the whole unit, or just put insulation above the ceiling tile?

 

[imac]

You may have a run into a phenomena known as "close coupling" in which the air space around the heat pump air handlers cabinets is actually transmitting vibration to the walls and ceiling. Typically, any air handler or HVAC device mounted above a false ceiling should have at least 3 feet of unresticed space around it to prevent this problem. The cabinets should be resiliently mounted and any connecting tubing, such as the refrigerant lines and condensate drain should be suspended with anti-vibration hangers. The electrical conduit should utilize flexible material the last few feet (if allowed in your jurisdiction).

I have run into a similar problem before and it's not easily solved. You will likley never be able to completely eradicate all the noise, but some beneficial relief may be possible at a reasonable cost. I urge you to consult an accoustical engineering firm for the best advice on how to reduce the noise and vibration. There are many companies that specialize in this area. I hope this helps a bit.

 

[stevenw]

Things to check -
Some heat pump ship with the compressors locked down to prevent damage. Check to see if the shipping locks have been removed.
Flexable connections installed at the unit duct connections?
Vibration isolation at the unit hanging points. Spring? rubber in shear?, installed correctly ?
Water source heat pumps, Hose kits or hard piped water connections?
Power connections in flexable conduit.

Insulation on the ceiling tile will not help much.
Additional insulation in the compressor compartment will do some good.
Insulation above the heat pump will heat eat some reflected sound.

Kinetics Noise Control has some helpfull information.

http://www.kineticsnoise.com