Can anyone in the region around southern New Hampshire (Merrimack) recommend an HVAC contractor who has the skills to resolve an issue with noise (vibration) transmitted from the outdoor unit into the house structure?  The noise during defrost cycles is really annoying, but even during normal cycles there’s still noticeable humming/thrumming.  This is an LG RED system (two outdoor units, one for a ducted air handler and the other for a wall-mount unit).

The line set from the outdoor unit is a straight shot (~3 feet) to where it enters the house and turns upward inside the 2×6 wall to the basement ceiling.  I recently replaced the fiberglass batt insulation in those wall cavities with mineral wool batts, and that helped reduce the noise but it’s still quite noticeable.  Some suggestions I’ve seen include installing vibration isolators in the refrigerant lines, adding mass (mass damper kit) to the lines, and adding a couple of hard 90-degree elbows to the lines.  The outdoor unit is mounted on a ground-mount stand with rubber vibration isolators.

I plan to install retrofit Titan line set boots at some point once the weather improves and remove the spray foam around the line set where it passes through the sheathing.

Bonus points if you can recommend someone who can manage to correctly insulate an ERV intake duct so it doesn’t drip condensation into my future basement gym space.

I’ll also need a new ducted system for my finished basement in progress, so there’s an additional sales opportunity for the HVAC contractor.

(For those who might ask, the builder’s HVAC guy who installed the system says the noise is “normal”, which is why I’m looking for someone else.)