I have just moved into a 14 story condo built in 2005 in portland oregon. The condo unit has a water sourced Trane heat pump model # Gehr02411j0210pr00100001000000000c0 . The building supplies hot or cold water to the unit depending on outside temp. The unit is installed in the ceiling of the master bedroom closet. There is a low frequency rumbling/buzzing when the pump is on. I installed a composite sound proofing barrier from soundproofcow.com along this wall in the assess area, which took care of 1/2 of the noise but it's still a problem. You can feel a vibration in the wall that abuts the bedroom and this seems to be the source of some of the noise. I see that the water source pipes are routed through this wall. I have thought of getting vibration decouplers installed on these lines ( they have very limited assess) but would that really eliminate the problem. Do I need to build a dummy wall isolated from the existing wall to really eliminate the noise?

Thanks, Bill