We have quite a large number of geothermal heat pumps on our site, the vast majority which are noisy.
We've left it to the contractor and manufacturer to sort out.
After several months of dicking around and reports, the manufacturer is blaming the contractor still.
Fact of the matter is the units are noisy.
I opened one up, because we field the complaints from the homeowners, and the problem persists.
Here's what I found;
The bottom of the machine has a compressor which vibrates like hell.
There is plenty of isolation on the lower part of the unit, so little vibration is transferred there.
Once you get into the fan chamber, the problem arises.
The lines from the pump to the heat exchanger are all hard lines. No flex couplings.
The heat exchanger is mounted to the top of the heat pump solidly. No isolation with the frame spot welded into place.
So the vibration is passed from the lines to the heat exchanger, which vibrates the top of the heat pump chassis.
I think that there should be a flex coupling, between the two, but there isn't.
The alternative is to dampen the vibration on the lines in this area, either by clamping or adding mass to the lines.
Testing with my Db meter, I was able to get a 5 Db drop in sound, just by grabbing the lines and holding them in my hand.
Disconnecting the seismic attachments, netted insignificant gains, although on some units helped reduce rattling.
I added 30# mass to the top of the heat pump. Netted me a 1 Db drop in some cases.
There is a flex coupling between the sheet metal ducting and the machine. Steel braided flex lines on all external connections to the machines
Isolation pads under the machines
Have any of you guys run into this problem and solved the issue?