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  1. #1
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212

    How do multi-zone ductless mini splits achieve multiple circuits, heads?

    My google and search skills are not turning up anything about how these
    things work in regards to multiple heads. I'm thinking they don't
    have a compressor for each head/circuit, but I have no idea how they
    achieve that? Maybe they have one motor and multiple compressing
    pumps? Scroll of some sort or what? I'm simply very curious as I had
    one today. (This house had three heads and two outside units.
    These things were 30 years old. Sanyo. Two of them are working just
    fine still. The one is low on refrigerant. A fast leak, evidently as it was
    cooling fine just a week ago. But I don't care about these units--so if
    anybody asks me about pressures and ambient and airflow (!), I SWEAR
    I'm going to slit my wrists. )

    My questions and interests are just about DMS in general.
    Thank you.
    Last edited by georgelass; 06-26-2013 at 11:39 PM. Reason: typo

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,416
    Inverter drive compressor

  3. #3
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212
    Oh, of course.

    (Waiting for kindly elaboration......or a link or something. Thank you.)

  4. #4
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212
    Okay, I googled.

    Sounds like a variable speed motor.
    But I'm really asking about the pumping of refrigerant with multiple circuits.

  5. #5
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,416
    The compressor varies its capacity from ~30% to 100+% depending on how many heads are calling and how many degrees its trying to cool down to.

  6. #6
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212
    But the circuits cannot all be flowing the same refrigerant. They must be separate.
    How is that accomplished? A diagram would be good.

    Thank you.

  7. #7
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,655
    Quote Originally Posted by georgelass View Post
    But the circuits cannot all be flowing the same refrigerant. They must be separate.
    How is that accomplished? A diagram would be good.

    Thank you.
    single compressor, single condenser, then it splits to the three different evaporators, each with a solenoid valve to turn flow on and off to that loop. variable speed compressor to maintain proper head pressures with any given situation.

  8. #8
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,343
    I believe all the multi zone units it's use electronic expansion valves. The valves is able to shut 100% when you turn a specific zone off.

  9. #9
    Join Date
    Jun 2013
    Location
    sherrodsville ohio
    Posts
    40
    look up mitzubechi MR. slim spelling not correct we have put several in work great.

  10. #10
    Join Date
    May 2010
    Location
    Oxford, UK
    Posts
    336
    Some of the older units (Fujitsu i think) didn't use an inverter comp, some had two comps and four circuits (two separate twin circuits) but kept refrigerant running through the idle unit. Most times it was ok but a few time ive seen where people have put one unit in a server room and the other one would sweat as it was in an unused office.

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