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Community and Q&A

Mini Split selection

Seth Holmen | Posted in Mechanicals on

I know this has been a well documented discussion on here. Yet here I am continuing it. I am close to making the final mini split unit selections for my house. I’m looking for advice on comparing three specific models. Let me know if I should be looking at others?

As background information, I am in Chicago and will be using two 1-Ton units to heat/cool my house + wood burning stove. House will have R 33 walls and R 50 roof. 2,100sf two story.

The unit I am currently considering is the LG – 9k BTU Art Cool Premier LGRED – 27.5 SEER (LA090HYV1 + LAN090HYV1). Here are some quick specs. BTU heating range = 1,023 – 20,472 btu. BTU Cooling range = 1,023 – 12,966. It has operation down to -13°F. A base pan heater is also included.

The other two units I am looking at are often reference on this site. The Mitsubishi 12k (MUZFH12NA + MSZFH12NA) and the Fujitsu 9k (ASU9RLS3Y + AOU9RLS3H). The fujitsu has a far better SEER at 33 compared to the 26.1 of the Mistubishi. The BTU ranges are similar. Mitsubishi is 3,700 – 21,000. The Fujitsu is 3,100 – 22,000. Fujitsu has a base pan heater. It’s unclear if one comes standard with Mitsubishi. The price point for these two units are similar.

The only reason that I’m leaning towards the LG is that the specs appear to be comparable but with a significant cost savings. What am I missing here? Quality / Performance?

Thank you,
Seth

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Replies

  1. Steve Knapp CZ 3A Georgia | | #1

    Seth,

    Do you have a Manual J report?

  2. Seth Holmen | | #2

    Yes, I have gone through the Manual J. My loads are about 27,500 BTU/hr. My thought process is that the wood stove will handle the majority of the heating and that the mini splits are my primary cool and backup heat. That is why they could be seen as slightly undersized for heating but should work well for the cooling loads. With all of that said I would rather focus this thread on discussing the specific units and their merits.

  3. User avatar
    Dana Dorsett | | #3

    The "...far better SEER..." of the 9LS3H is pointless at Chicago's summertime humidity levels. To keep up with the latent loads any of them will have to operate in "DRY" or "DEHUMIDIFY" mode a lot of the time (at a lower as-used SEER.) They're all good.

    I'm not sure how a high-performance 2100' house with R33 walls and an R50 roof comes up with a cooling OR heating load of 27,500 BTU/hr. A "typical" code minimum 2100' house would have a cooling load of less than 20,000 BTU/hr @ 90F (a typical Chicagoland 1% outside design temp) and a heating load of about 25,000 BTU/hr @ 0F (the 99% outside design temp at Midway Airport.) A high R house should come in under 20K for either, unless it has a LOT of window, particularly west facing unshaded window taking on a lot of afternoon solar gain.

    The some models H2i Mitsubishis usually come with pan heaters pre-installed as standard equipment, but with others it's an accessory that may be installed if needed- read the specs. (On the MSZ-FH12NA & MUZ-FH12NA single mini-split submittal sheet the pan heater is listed as an accessory: http://meus1.mylinkdrive.com/files/MSZ-FH12NA~MUZ-FH12NA_Submittal.pdf )

    Both Mitsubishi & Fujistu (as well as Daikin) are manufactured in Japan to fairly high quality control levels, and have fairly extensive distribution, training, and support infrastructure in the US. While LG is a first-tier Korean manufacturer, the level of support in the US isn't quite as good, and (at least in years past, according to installer scuttlebutt), the quality control isn't always what is should be. If you get a lemon your kind of stuck in warranty negotiation hell, but if you get a good one (and the installer didn't manage to screw it up) they're pretty good.

    I see a few LGs in my location (central MA), but I see a LOT more Mitsubishi units than any other vendor. Mitsubishi's regional training and design center is less than an a half-hour's drive from my house, and the number of certified local factory trained techs & installers is large, which makes it a much less risky choice.

    Of course support is sometimes spotty with the Japanese vendors too, especially if it's not a popular model (but sometimes even if it is) it can sometimes take weeks or months for replacement parts to arrive. I have a relative in WA whose FE18 had extensive damage from a powerline fault, where it took a bit over a month for a critical part to be manufactured & shipped to the local support person. To their credit (and my amazement) Mitsubishi covered the damage to this (then three year old) unit, including the diagnosis & repair labor, despite the damage being caused by an exploding transformer on the local power distribution grid that destroyed lots of other appliances in homes in that area. I suspect most other vendors would not have been so accommodating, but maybe.

    1. Wankel7 | | #6

      "The "...far better SEER..." of the 9LS3H is pointless at Chicago's summertime humidity levels. To keep up with the latent loads any of them will have to operate in "DRY" or "DEHUMIDIFY" mode a lot of the time (at a lower as-used SEER.) They're all good."

      Can you expand on that some? Why is seer not an accurate measure of performance in humid climates?

      1. User avatar
        Dana Dorsett | | #7

        The higher SEER numbers are tested at a higher cfm per ton of compressor output, which results in a high efficiency number, but less latent cooling/dehumidification. Lowering the cfm/ton ratio lowers the efficiency numbers in the test, but improves the latent to sensible cooling ratio.

        With a mini-split operated in "DRY" or "DEHUMIDIFY" mode it sets the coil temperature to a minimum and the blower to the speed that keeps it there, which is not the highest sensible cooling efficiency mode. The latent/sensible cooling ratio in high-efficiency mode is fine for drier climates, but will fall behind on latent load in more humid climates creating cool-but-clammy indoor conditions, so it's good to have the mode options, even though it's technically not as efficient.

  4. User avatar
    Stephen Sheehy | | #4

    I have nothing to compare it to, but our Fujitsu 9 RLS3H and 12 RLS3H work well. Other than cleaning the filters, which is quick and easy, they require no attention. We're in zone 6 Maine.

  5. Seth Holmen | | #5

    Thanks for the input. There is a good chance the Manual J could be off a bit. However, I do have a large amount of glass and the ceilings are tall. 10ft ceiling on the first floor and 9ft on the second. The house is oriented for solar heat gains on the South. Its on a large wooded lot so the West sun will be shaded out. There will be a wide and deep porch along the broad South elevation at some point to help shade the first floor windows.

    Do you have further insights into the dry modes or what brand / model performs the best? On a few other sites I've seen complaints on the Mitsubishi not being able to reduce humidity levels. The LG model lists water removal of 3.2 pt / hr. The Fujitsu model is listed at 2.75 pt / hr. I could not find the Mitsubishi data.

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