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Noise Level of Minisplit Head in Off Mode

tanzerson | Posted in Mechanicals on

Hi again.   I’ll be installing a mini-split and am considering going with a multi-split with two main heads heating the main upstairs and downstairs and a third in our main bedroom (all wall mounts).   We currently keep heat off in the bedroom most nights in the winter and don’t have AC.   The bedroom would only be used on extreme cold nights and for cooling for maybe 2 or 3 weeks in the summer so the bedroom unit will often be off at night.

I understand with a multi-split (Mits or Fujitsu) that all units circulate fluid whether their fan is on or not,  Does anyone have experience with how much noise a wall unit makes when off and the other units are operating?  Does it make enough noise to disturb sleep?

Also, with the fan off and warm or cold fluid circulating, does the unit release much heating or cooling energy?


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  1. GBA Editor
    Kiley Jacques | | #1

    I’m giving your question a bump. I read through some related questions and came across this repsonse: The outdoor unit should sound like this:, and the indoor unit should be silent until the cycle is over. You'll hear refrigerant sounds when it starts back up again.

  2. paul_iowa | | #2

    Hey, Yes, don't put a multizone in a bedroom. I have a Fujitsu AOU36RLXFZH hooked up to two floor mounts and a wall mount. One of the floor mounts is in the bedroom and it makes an annoying amount of sloshing/gurgling sound when the unit is completely off. We've coined it Mr. Bubbles.

    Like you, the bedroom is on the 2nd floor and stays pretty warm most of the winter (Decorah, IA), and we only turn that head on a few weeks of the winter (and most of the summer). It seems to make less noise when it's on and running than it does off. And for whatever reason it makes less sloshing noise in shoulder seasons when there isn't much load on the compressor. More heating demand from the other two heads seems to result in more noise from the unit that's off. Seems like it should be the opposite, given each head is 9-15k btu, and the minimum modulation of the compressor is about 10kbtu. Interestingly, when off in AC mode it doesn't make a lick of noise, but you can feel the cold coil, meaning refrigerant is looping through.

    I've contemplated separating the bedroom floor mount off onto its own single zone compressor (Fujitu's multi-zone floor unit is the same as their single zone) once I finish remodeling the last portion of the house, and adding a head to the newly remodeled part.

    Best of luck!

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