I bought a home with a older hot tub, has two pumps (1 speed, and 2 speed)
I had to turn the spa so the pump side now faces the home and the noise level has increased 2 to 3x.
After some troubleshooting, I found much of the noise entering the house is from vibration of the enclosure when the circulation pump is on (pump that turns on when the heater is on)
When I remove the doors (looks like PVC material/panels) in front of the pump, the noise going into the home reduces a ton to become almost unnoticeable. (of course, this is way less energy efficient as much of the heat is also leaving through the open cavity)
Any recommendations on mitigating the vibration?
I thought of a few things...
adding mass with plywood/MDF - the downside here is there is not much rooms inside the cavity and putting the doors on is already a royal PITA.
adding mass with mass loaded vinyl - this is expensive, especially if it does not work well.
adding closed cell foam - this is relatively inexpensive but not sure how much it will dampen the vibration and reduce the sound transmission fro the pump
anyone have ideas and/or dealt with this before?