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  1. #1
    Join Date
    Sep 2013
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    Charlotte, NC
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    Question Mitsubishi 30+ seer minisplits terrible at dehumidifying?

    I am looking to have a minisplit installed in my garage which is a small one car garage mostly below grade and very well insulated. This will be installed in Charlotte, NC which is humid in the summer and need a unit that is good at dehumidifying as the garage gets extremely humid. The space only needs a 6,000 BTU unit. Researching units it seems the high efficiently (30+ seer) Mitsubishi units are horrific at dehumidifying. I wanted to make sure I am not missing something, are the high efficiency units really that bad at dehumidifying? Does the Dry mode do anything to improve that?

    I could go with a 24.6 seer unit but it is over-sized and the inverter BTU output only ramps down to 3,600 BTU while the 30+ seer units ramp down to 1,700 BTU. Any thoughts?

    Mitsubishi units moisture removal:
    MUZ-FH06NA (out), MSZ-FH06NA (in), 6000 BTU, 31.1 seer: 0.2 pints\hour
    MUZ-FH09NA (out), MSZ-FH09NA (in), 9000 BTU, 30.5 seer: 0.6 pints\hour
    MUZ-GL09NA-U1 (out), MSZ-GL09NA-U1 (in), 9000 BTU, 24.6 seer: 1.5 pints\hour
    Misubishi M-series engineering manual

    Name:  Mitsubishi 30+ seer minisplit.PNG
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    Name:  Mitsubishi 25 seer minisplit.PNG
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    Daikin unit moisture removal:
    RXL09QMVJU (out), FTX09NMVJU (in), 9000 BTU, 20 seer: 2.4 pints\hour (0.3 g\h)

  2. #2
    Join Date
    Nov 2006
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    Athens, Ohio
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    It seems to me humidity is the primary issue. Have you thought about using a dehumidifier and a window air conditioner?
    AOP Rules: Rules For Equipment Owners.

    Free online load calculator: http://www.loadcalc.net/


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  3. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
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    and remove even less during low or no load conditions.

    That's why you'll need a small dehumidifier!

  4. #4
    Join Date
    Sep 2013
    Location
    Charlotte, NC
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    Thread Starter
    Thanks for the responses, I do have a small dehumidifier but it makes the space even hotter in the summer. I am looking to add a minisplit to heat and cool the space so I can do small projects in the space. The garage is in a townhome which is on hill so only the back is exposed above grade. Unfortunately no windows for a window unit. I was hopping to get a minisplit that is good at dehumidifying to reduce the need for the dehumidifier. I am just so confused by the Mitsubishi data, would there top of the line unit really be so bad at moisture removal?

  5. #5
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    Aug 2002
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    Whats wrong with the data?

    .2 pts per hr on the small system

  6. #6
    Join Date
    Sep 2013
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    Charlotte, NC
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    Thread Starter
    Pecmsg, the number seemed low as the Mitsubishi 25 seer 9K pulls out about 3 times more moisture than the 30 seer 9K unit. LG's 9K 24 SEER unit pulls 2.7 pt\h which is 4.5 more than the Mitsubishi 30 seer 9K unit. This is such a big difference I wanted to make sure I am not missing something.

  7. #7
    Join Date
    Nov 2006
    Location
    Athens, Ohio
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    No ductless unit will run much in a room with a low load. I suggest you size the unit for heating and cooling capacity because they are intended for heating and cooling use. Dehumidification is a side effect of cooling. The "dehumidification" setting is just cooling mode without any temperature control to turn it off.
    Dehumidifiers are for dedicated dehumidification.

    At home I have a heat pump AND a ducted dehumidifier. My system can maintain 48-50% RH even when occupied and the outdoor conditions are 83* with 90% RH.
    AOP Rules: Rules For Equipment Owners.

    Free online load calculator: http://www.loadcalc.net/


    There = not here. Their = possessive pronoun. They're = they are
    It's = contraction of it is. Its = the possessive form of it
    Too = also. To = expressing motion. Two = 2
    Then = after that, next. Than = indicates a comparison.
    Questions should end with a question mark "?" Statements end with a period "."

  8. #8
    Join Date
    Sep 2002
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    The dynamics of moisture removal are the exact opposite of the dynamics of high efficiency cooling.

    PHM
    ----------




    Quote Originally Posted by LukeS View Post
    I am looking to have a minisplit installed in my garage which is a small one car garage mostly below grade and very well insulated. This will be installed in Charlotte, NC which is humid in the summer and need a unit that is good at dehumidifying as the garage gets extremely humid. The space only needs a 6,000 BTU unit. Researching units it seems the high efficiently (30+ seer) Mitsubishi units are horrific at dehumidifying. I wanted to make sure I am not missing something, are the high efficiency units really that bad at dehumidifying? Does the Dry mode do anything to improve that?

    I could go with a 24.6 seer unit but it is over-sized and the inverter BTU output only ramps down to 3,600 BTU while the 30+ seer units ramp down to 1,700 BTU. Any thoughts?

    Mitsubishi units moisture removal:
    MUZ-FH06NA (out), MSZ-FH06NA (in), 6000 BTU, 31.1 seer: 0.2 pints\hour
    MUZ-FH09NA (out), MSZ-FH09NA (in), 9000 BTU, 30.5 seer: 0.6 pints\hour
    MUZ-GL09NA-U1 (out), MSZ-GL09NA-U1 (in), 9000 BTU, 24.6 seer: 1.5 pints\hour
    Misubishi M-series engineering manual

    Name:  Mitsubishi 30+ seer minisplit.PNG
Views: 362
Size:  86.1 KB

    Name:  Mitsubishi 25 seer minisplit.PNG
Views: 351
Size:  96.0 KB


    Daikin unit moisture removal:
    RXL09QMVJU (out), FTX09NMVJU (in), 9000 BTU, 20 seer: 2.4 pints\hour (0.3 g\h)
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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