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Risk of harmonic noise for Mitsubishi split outdoor unit

I'm in process of finalizing an install for a ductless heat pump system. For my master bedroom, the indoor unit needs to be connected to a dedicated outdoor unit (MUY-GL09NA). If that outdoor unit were to be placed on the ground, it could only go adjacent to another outdoor unit serving our kitchen, and that's too much of an eyesore in our backyard for my wife and I to stomach. So the installer can put it on a wall bracket in the back of the bedroom above a mini roof where it would be mostly out of sight. But he's cautioned more than once that there is a 'chance' (not sure of percentages) that there could be some discernible harmonic noise (not sure how loud). I'm not worried about any noise outside, but I'd be concerned about any bothersome noise inside (although hopefully it's white noise...and we'd only run the unit while sleeping at night). Does anybody have any direct experience with this harmonic noise? And there's truly nothing that can be done to mitigate the noise? For example, I found this link.... http://www.kellettent.com/blog/keeping-vibration-off-the-wall-with-mini-split-hvac/

Thanks, Vlad


  • Firecontrol933
    Firecontrol933 Member Posts: 73
    Each unit, install and home structure are different in some way or another. Is yours going to have an issue is anyone's guess. The outdoor unit can be mounted to the bracket via vibration isolation anchors that are outdoor rated. Will it be 100% effective? See above.

    Harmonic noises are by nature situation unique taking into account all of the parts and how they interact. You could end up with an entire wall of your home becoming a giant low frequency speaker.
  • BobC
    BobC Member Posts: 5,479
    They do have ground mounted risers that lift the unit about 16" off the ground. If your normal snow depths are not more that may be a solution.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • njtommy
    njtommy Member Posts: 1,105
    Most ductless wall brackets have rubber feet where that red circle is on the picture is. This would also be an adjustment point to level the unit.

    They only time you would most likely get a noise or vibration would be under peak loads or demands when the unit is running 100% capacity. Other then that it will just Cruze right along with our even hearing it run.