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Minisplit question

RWB1 | Posted in Energy Efficiency and Durability on

Let me first say …great forum, been lurking for a few months and have picked up some great tips.

I live in upstate NY zone 6A and have 3 rooms of my house that I cannot send ductwork that have electric heat.
I have a 2200 sq ft ranch with a 2nd floor master suite addition that has a family room underneath..mid level between the first floor and basement and a sunroom off that , 6 windows, slab on grade with french doors and a sloped ceiling with no attic.

I had a manual j done that came up with the following:

Sunroom heat load 15,115 btu’s and cooling 3761

Bedroom heat 6725 and cooling 1771

Family room heat 4852 and cool 771 btu’s

I have had 3 different contractors come give estimates on a 3 zone system for these rooms and have received 3 different configurations.

Contractor #1

sunroom = 9k wall unit
family room= 7k
bedroom= 7k
24k fujitsu low temp outdoor unit

Contractor # 2

sunroom= 12k
family room = 9k
bedroom = 9k

36k fujitsu outdoor unit, low temp

Contractor # 3

sunroom =15k floor unit
family room =12k
bedroom = 9k

36k fujitsu outdoor unit , low temp

2 contractors took some quick measurements and did the estimates….one looked around and told me he has done so many he knows exactly what I need !!

These are reputable, local contractors , one being a fujitsu elite dealer.

They tried to get me to use mitsubishi and LG but I leaned toward fujitsu because of the rave reviews by most.

At this point I am not sure what to do….get more estimates ?
Buy the equipment online and have a friend install it (union plumber 30 years)

And what brand will give me the best bang for my buck, performance wise as well as longevity.

I was told by an e-tailer trying to sell me equipment that LG was the way to go because they had no “shut off ” point…and the parts are now readily availabl

Any insight is greatly appreciated as this is all new to me

thanks Bob

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  1. Expert Member
    Dana Dorsett | | #1

    The 99% outside design temp matters, as does the model number. Cold climate mini-splits have higher capacity at cold temps than those designed for more temperate climates, but all lose capacity with falling out door temperatures.

    The number the manufacturers choose for rating their mini-splits is up to the manufacturer, and the capacities aren't the same. There is no equivalence between a 9K unit from one model line to that of another- the 9K is the modulation level at which the opted to test it,'s SEER efficiency, not necessarily it's maximum capacity. Similarly, the modulation level at which it's HFSF is tested is also somewhat arbitrary. So it's not unusual to see a range from 3/4 ton to 1.25 ton to cover a 15K load 0F or whatever, depending on which model & vendor.

    For instance, in many ways the Fujitsu 9RLS3H is more like a 12K in terms of capacity from some other vendors. If your 99% outdoor design temp is in positive digits F it'll probably fully cover the 15K load for the sunroom, (but probably not if your outdoor design temp is -8F), whereas a temperate-climate mini-split would need a 1.25 or 1.5 ton unit to have sufficient capacity.

    It's hard to go wrong with either Fujitsu or Mitsubishi cold-climate mini-splits in this region, both of which have pretty good technical and distributor support, but find out where they are relatlive to your location. LG's support is a bit spottier, but again, find out where the distributor is located, and how many certified trained installers there are in your region.

    I don't trust any of them to "know what you need" by a simple walk through. Down load the engineering manuals and check the heating capacities at your 99% outside design temp.

    Unless it dwells in the mid -20s F for hours every winter there is no need to shy away from Mitsubishi's. Even though it will turn off at some point cooler than -18F according to their documention, there are field reports of them chugging away just fine below -20F.

  2. RWB1 | | #2

    Dana, thank you for the answer....I was leaning toward Fujitsu but noticed in the specs that the minimum btu is 3100 for most wall units. Seeing that the cooling load is well below that for the bedroom and family room will this work for me ?
    I want to do it right the first time but having a contractor swear that I only need a 9k unit for my sunroom, knowing that the load is 15k for heat makes me leary. Looks like the Fujitsu 9k unit will put out 12k so...On the cooling end I have heard of systems being oversized and causing a room to be super cold but but clammy...I suppose from not running long enough to remove the humidity.

    Again, I appreciate the insight as I am trying to educate myself best I can


  3. Expert Member
    Dana Dorsett | | #3

    The max heating output of the "9K" -9RLS3H Fujitsu @ 47F is 22,000 BTU/hr, but tested for efficiency at a "nominal" 12,000 BTU/hr @ 17F (which is not it's maximum output at that temp.)

    The max heating output of the "12K" -FH12NA Mitsubishi is 21,000 BTU/hr, tested at (and constrained by firmware to) 13,600 BTU/hr @ +17F.

    So why is one a 1-ton, the other a 3/4 ton?

    Your 99% outside design temperature is...??

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