Hey all, Thanks in advance for all of the great advice that everyone offers on this forum. It continues to be a HUGE help. I have a new Water Furnace Envision 3 ton split unit with the cube in a bedroom closet and the blower in the attic directly above. The rooms are really small, about 10x10 and I was worried about the noise from the cube. The installer described the running sound like a refrigerator compressor, and the WF manual describes it as "whisper quiet." The blower is really quiet--much quieter than the blower on my heat pump in another home. The issue is with the hum from the WF cube. It sounds like a plane is taking off in my closet. You can hear it clear across the house. I already spent $400 on a sound blanket for the unit and sound panels to surround the closet, but the hum sound more like an industrial walk in fridge on an ocean liner vs the whisper quiet one they describe it as. Has anyone else had this problem? I know that Envision will provide the installer with a thicker sounds wrap for the compressor which I will request, but I am not confident that will do the trick. I have heard about people buying new feet for their units so the vibration does not travel through to the floor. Not sure if there is much else that we can do--do we need to keep living in the flight path every time the unit kicks on? Thanks for your help and any advice or past experiences anyone can offer.

Couple thoughts;
sounding like a refrigerator should be true.
don't give it feet, insulate the whole underside (just holding 4 corners up lets the bulk of the underside act like a drum).
Hard to convey noise through written text, what does your installer say?
Should be quieter than your old furnace 9but that probably wasn't in your closet).
Good luck,
Joe

Check that ALL compressor shipping bolts have been removed. I've been burned by that.

I just got through assisting on an Envision split job and I was astonished how quiet the compressor section runs - truly like a refrigerator. Since you are not experiencing that, something is bad wrong, and wrapping the compressor in a thicker blanket likely isn't the fix.

It is sometimes difficult but sometimes important to differentiate between sound originating from the unit vs sound originating from vibration of the unit causing something else to vibrate much more noisily.

Again, check shipping bolts.

I work for the FAA and let me assure you FAA regulations do not allow planes to take off in closets. You can rest easy that it's not a plane. 

 

Thanks guys. I will check the shipping bolts. I was intrigued by another posting that said the owner used vibration absorbing feet on his unit to help the sound issue, and it worked. He used http://acousticalsurfaces.com/ and one of the products on the VIBRATION MOUNTS - HANGERS & PADS link. I bought my wall, ceiling and blanket sound insulation from these guys, but did not want to venture into the absorption pads and spring feet.

I do suspect that a portion of the noise is coming from floor vibration. The unit is on rubber feet, but sits right on the harwood floor. Joe.ami, you said not to give it feet, but to insulate the underside. Do you mean physically lifting the unit and putting one of the wall insulation boards I used underneath the unit? Would that be better than using sound/vibration absorbing feet?

Thanks for the help everyone.

1 or 2" foam board (i.e. exterior wall insulation at Orange store) is my preference. Sound absorbing feet will also prevent unit from transfering noise to floor, but bottom of cabinet is taught steel that could act like a drum head. Much like a speaker cone, vibrations could reverberate and be conveyed by an underside that is not supported. 
I know of no manufacturer that recommends corner blocks only.
J 

for the split system to be installed properly WFI requires a solid base under there units. they sell a foam pad usually installed under a water to water unit but can be used here as well, If you even use the standard plastic base under the unit the sound of vibration would be absorbed by the pad. The invision units have triple isolation mount with a special metal mountiing bracket that dissipates sound. The corner pads are a bad idea. as mentioned by another its like a cone of speaker with corner mounts. even a simple a/c pad used for outdoor units would be better than using the corner pads. Just my input on this

Dcislander, You didn't say if this is open or closed loop. If it's open loop to much water velocity can have the same sound as a jet taking off. Be sure the unit is only seeing the flow it needs. NSZ036-38 4.5 GPM max. WaterFurnace recommends a full pad under the equipment as others have said, and be sure the compressor tie down bolt is removed. More than likely it is a flow issue as any compressor noise would be more mechanical in nature.

Thanks all. This is a closed loop system. There is no pad under the unit now, and I suspect that once one is added it will take care of much of the noise, as it seems to be a combo of vibration and compressor sound.