I have a 42k Mitsubishi system (MXZ-5C42NA2 – non hyperheat), located in Seattle (zip code 98107), installed on the north side of my 2000 sq ft, 1946 house, mostly uninsulated. The system has 4 heads, all the “FH” model, 6,9,12 and 15k. The outdoor unit is mounted to a plastic pad.
I noticed that in heat mode, when 1 or 2 units are calling for 1 degree of heating, the system is pulling about 900-1100W (as seen in the Sense app) and as it modulates up and down, it sounds like a diesel truck/apache helicopter is idling outside (around 40hz I believe). When you check the outdoor unit, the ground is definitely vibrating, but somehow the inside of the house magnifies it. The sound is noticeable even at the furthest points from the unit, like upstairs, on the other side of the house.
The installer has already come out, confirmed the unit is operating properly, all lines are secured and not vibrating, and added these cork insulators under each foot, but this has done zero to fix the issue. They are willing to come back out again and take drastic measures like depressuring the unit to repack the ground and/or adding gravel, foam pads, etc. I can tell I should probably suggest the course of action, as they’ve never encountered this issue.
I got advice from some other folks that I can do one of two options - have an 8-12" concrete pad poured or try spring isolators. Yes, operating all the heads at around the same temperature increases the load on the system, and mostly mitigates the issue but I can still hear it modulating, and I have bad hearing!
I also noticed that the pad bolts are loose and can be easily pulled up - not sure if this normal?
What should the best course of action be to mitigate these bad vibrations?
youtu.be/kpe0E7FIWUs – Outdoor Unit
youtu.be/6hZtsmvNsuQ – Outdoor Unit 2nd Video
I noticed that in heat mode, when 1 or 2 units are calling for 1 degree of heating, the system is pulling about 900-1100W (as seen in the Sense app) and as it modulates up and down, it sounds like a diesel truck/apache helicopter is idling outside (around 40hz I believe). When you check the outdoor unit, the ground is definitely vibrating, but somehow the inside of the house magnifies it. The sound is noticeable even at the furthest points from the unit, like upstairs, on the other side of the house.
The installer has already come out, confirmed the unit is operating properly, all lines are secured and not vibrating, and added these cork insulators under each foot, but this has done zero to fix the issue. They are willing to come back out again and take drastic measures like depressuring the unit to repack the ground and/or adding gravel, foam pads, etc. I can tell I should probably suggest the course of action, as they’ve never encountered this issue.
I got advice from some other folks that I can do one of two options - have an 8-12" concrete pad poured or try spring isolators. Yes, operating all the heads at around the same temperature increases the load on the system, and mostly mitigates the issue but I can still hear it modulating, and I have bad hearing!
I also noticed that the pad bolts are loose and can be easily pulled up - not sure if this normal?
What should the best course of action be to mitigate these bad vibrations?
youtu.be/kpe0E7FIWUs – Outdoor Unit
youtu.be/6hZtsmvNsuQ – Outdoor Unit 2nd Video
source https://hvac-talk.com/vbb/showthread.php?2225834-Mitsubishi-42k-Outdoor-Unit-40hz-vibration-sounds&goto=newpost
No comments:
Post a Comment