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Positioning Minisplits

soarak | Posted in General Questions on
I am finishing the attic in Southern New Hampshire, 800 sq feet, with very good insulation and 4 windows.
I had a few contractors come in and giving me quotes for mini splits. None of them did any heat loss calculations. Most proposed 2 heads totalling 24k BTU. I did Manual J calculations and came with a number around 8.0k, which probably is still overestimated by a touch.
So the system I am after is 9k, single head, either positioned above the window to blow along the longest dimension of the room, about 38 feet, or floor unit positioned in the middle of the room blowing along the short dimension of the room, about 20 feet. I feel the floor unit might be able to distribute the heat a little better, considering it needs to blow shorter distance to reach all places, while the over the window unit will have a long way to blow (38 feet). Not sure which position would provide greater comfort.
It seems the over the window units are a tad more efficient.
My second question deals with brand. I am looking at either Mitsubishi or Fujitsu. My contractor, different than the other equipment pushers, will install the unit I want. I am thinking the Fujitsu might be a bit more efficient in really cold weather. I am predominantly concerned about heating.
Any data would be appreciated. Andrzej

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  1. Eric_Old | | #1

    I live in southwest NH, have experience with ductless mini splits installed in my home (heating whole home with them).

    Yeah, the 24K is a joke - your 9K seems ok without knowing anymore details.

    I really don’t think it matters what choice you make (floor or wall mounted). It seems that it is all one open attic, so they will move air no problem.

    I think it more about aesthetics. I have all wall mounted and have no problem getting the “hot” air to push to the floor. My wife didn’t want the floor unit.

    I have Mitsubishi and they are awesome. No complaints.

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