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  1. #1
    Join Date
    Sep 2014
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    NW Arkansas
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    Home Mini-Split Design help.

    Hello,

    We have installed a lot of mini-split units but have not installed a whole house system yet. I am looking for advice on how to design it; right now I have a about three different options to go with (that I can think of) but the best one is listed below. I don't want to use the ducted if I can avoid it since the efficiency goes down.

    1st:
    Outdoor: MXZ-4C36NAHZ (Mitsu Multi head)
    Indoor:
    1 - A MSZ-FE18NA for the Dining, Living, Kitchen, Hall (On Living room wall facing kitchen)
    2 - A MSZ-FE09NA-8 for the Master Bed, Bath, closet (On Master bed wall facing bath and closet).
    3 - An MSZ-GE06NA-8 for the West Bedroom and one for Bedroom 1. (Would hang on the North wall)

    My concerns are that the garage gets very hot and it will heat up the shower/laundry/master closet/hallway areas. I also worry about the hallway bathroom since it is on an outside wall. The home was built as a spec house so build quality isn't the best. They have sealed up some areas but not much has been improved.

    Any suggestions? As it stands this will be an expensive quote and i'm not sure it will handle all the areas.
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  2. #2
    Join Date
    Aug 2013
    Location
    Visalia California 93291
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    Your Man J is off -

    You have a vented attic why not go Small Package Product and Ducted if there is room
    "If you think it is expensive to hire a professional to do the job, wait until you have hired an amateur"

    Red Adair

  3. #3
    Join Date
    Sep 2014
    Location
    NW Arkansas
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    There is actually a central air system in place (oversize and bad duck-work). The customers really want the efficiency of the mini-splits and the zone control; they are big into tech stuff. I put a quote for re-doing existing system with high efficiency but they don't want that. The system is nearing its lifespan so they are looking to replace the whole thing. Eventually using the current ductwork for an erv type setup.

    Where did we mess up on the manual J? I do see where 16BR-19-ml (unvented attic) was selected which is wrong... I will have to fix that since it is vented.

  4. #4
    Join Date
    Aug 2013
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    Visalia California 93291
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    You should only have 4 people, you have 6, equipment should only be 1200 Sensible 600 Latent you have 5881 Sensible and 1409 Latent
    "If you think it is expensive to hire a professional to do the job, wait until you have hired an amateur"

    Red Adair

  5. #5
    Join Date
    Jul 2015
    Location
    Ottawa,ONT
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    37
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    Last mini split multi unit I put two heads one at each end of the house in the common areas. Not sure if I would put them in a bedroom. One in the living room and one at the other end of the house both facing toward the middle of the house would be good IMO. then they have the option to add another head in the future if they want to expand.

  6. #6
    Join Date
    Sep 2014
    Location
    NW Arkansas
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    Quote Originally Posted by PrimeHVACsys View Post
    Last mini split multi unit I put two heads one at each end of the house in the common areas. Not sure if I would put them in a bedroom. One in the living room and one at the other end of the house both facing toward the middle of the house would be good IMO. then they have the option to add another head in the future if they want to expand.
    Did the two units cool the whole house fine? Even the bedrooms and bathrooms? If so that would work very well from a cost standpoint.

    Quote Originally Posted by lkapigian View Post
    You should only have 4 people, you have 6, equipment should only be 1200 Sensible 600 Latent you have 5881 Sensible and 1409 Latent
    The Sensible and Latent was selected from the "internal load" section on the individual rooms. Things such as fridge, toaster, plants, tv... The customer stated they usually have up to 6 people in the kitchen/common area. Was I suppose to select these differently?

    Thank you for your help. I am still getting adjusted to load calcs.

  7. #7
    Join Date
    Aug 2013
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    Visalia California 93291
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    Quote Originally Posted by Snaple4 View Post
    Did the two units cool the whole house fine? Even the bedrooms and bathrooms? If so that would work very well from a cost standpoint.



    The Sensible and Latent was selected from the "internal load" section on the individual rooms. Things such as fridge, toaster, plants, tv... The customer stated they usually have up to 6 people in the kitchen/common area. Was I suppose to select these differently?

    Thank you for your help. I am still getting adjusted to load calcs.

    ACCA Manual J Protocol you have to assume the people in the home will move @ some point and new people will move in, doing it your way will push you to an oversize- There is plenty of slop without adding loads ( though the software does have that function ) Energy Start QI ACCA 5 will not allow it 1 person per bedroom in the home +1 1200 Sensible 600 Latent additional for the kitchen that is it- In your current scenario you could push up another 1/2 ton...........Mute point with an inverted mini split, but for future calculations might be something you want to consider
    "If you think it is expensive to hire a professional to do the job, wait until you have hired an amateur"

    Red Adair

  8. #8
    Join Date
    Jul 2015
    Location
    Ottawa,ONT
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    37
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    My customer has never been happier but keep in mind they were using a portable plug in AC before not a ducted unit. They keep the doors open and the whole house is very comfortable. But short of putting a unit in every room it will never be perfect. You have to gauge how much money they want to spend too.

  9. #9
    Join Date
    Sep 2014
    Location
    NW Arkansas
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    Thank you for the info and suggestions. I will adjust the load and try for 3 heads, one above front door, one in living room facing kitchen/hall, and one in master (they will need this one to be happy even if they don't need it)

  10. Likes lkapigian liked this post.
  11. #10
    Join Date
    Oct 2011
    Location
    Bothell, WA(Seattle)
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    Quote Originally Posted by Snaple4 View Post
    Thank you for the info and suggestions. I will adjust the load and try for 3 heads, one above front door, one in living room facing kitchen/hall, and one in master (they will need this one to be happy even if they don't need it)
    Man, you got it. Being that it is an inverter system just err on the high side a little and you will have a happy customer.

  12. #11
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
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    For bathrooms/closets etc I use a slim duct and drop down the closet or hall ceiling.

    This is my latest install, not done yet. I think it gets 18 sales eer.

  13. #12
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
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