Overall, William Morse is delighted with his minisplit heat pumps—except for one detail. The noise.
“I have several Mitsubishi units wall mounted on an older (1900) home,” Morse writes in this Q&A query originally posted last fall. “I have terrible vibration/noise from all of them. Even on low, from the inside it sounds like a diesel truck idling outside.”
On the outside of the house, there is no noise at all. Morse even resorts to looking at the compressor fan to make sure the unit is running. He’s asked the installer to move the compressors from the wall to a ground-mounted stand, a move that will cost $2000.
“The noise has been a problem from the beginning and the installer has been unresponsive,” Morse adds. “Has anyone had any luck either getting the installer to fix a problem like this, or by going to the manufacturer?”
That’s the focus for this Q&A Spotlight.
Use vibration isolators, not standard mounting bolts
Zephyr7 suggests that the conventional mounting bolts be replaced with vibration-damping connectors. He steers Morse to a company called McMaster Carr, whose website lists a variety of these mounts. These vibration isolators will make a big difference, Zephyr7 says, but they don’t always solve the problem.
“It is usually best to use a stand,” he says, adding that the stands could be built in such a way that the compressors would not have to be moved very far.
“I wish it were that simple,” Morse replies, “but they hung them up pretty high on the wall, which I think exacerbates the vibration problem. They also already added the isolators.”
Try spring mounts
Akos acknowledges that there’s no easy fix to the vibration problem. Stock rubber mounts do nothing to dampen the low-frequency noise…