Busting Myths on Ductless Mini-Splits: Part II

Revisit the Four Myths that I Proposed were “Busted” Three Years Ago

Revisiting the July, 2013 post, “Busting Four Myths About Ductless Mini-Splits”

When I wrote the “Busting Mini-Split Myths” article in 2013, I did not think it would become the most viewed article on our new website but it has over 365,000 page views and counting! I guess I would attribute the popularity of this topic to how new these systems are and how different they are from conventional, ducted, central HVAC systems, which are found in over 80% of the homes in the U.S. However, in addition to the volume of traffic the number and quality of the posted comments and questions has also been remarkable (over 270 to date).

Although we started out trying to provide a balanced view on this new technology for consideration, I found that I also learned some things as the user feedback continued to come in. This led our team to do some additional consumer research into the U.S. Mini-Split phenomena and this research will now appear in some new articles written by Eric Strausbaugh.  Without going into the details of the study, I thought I would use some of the findings from the study, along with the knowledge contained in the many posts on this site, to revisit the four myths that I proposed were “busted” three years ago.


Myth #1 – The sales of ductless mini-spit systems continue to grow and will dominate the U.S. market.

Status: Still Busted. While mini-splits are growing a little faster than the sales of central systems on a unit basis, the dollars spent on these systems and the number of BTUs of capacity getting installed is still a fraction of that spent on traditional central systems. The reason for this is that the majority of the installed base of homes (over 80%) have pre-existing ductwork. It is simply less expensive to replace a ducted system with another ducted. The air quality and humidity control benefits from central AC are also contributing factors to the staying power of central systems.

Myth #2 – Ductless mini-splits are ideal whole-home HVAC solutions in the U.S.

Status: Still Busted. Our recent research suggests that only a small percentage of people are trying to use mini-splits as a whole-home heating and air conditioning solution; these are mostly in very small homes with no existing ductwork available. What appears to be more popular recently is the “hybrid” approach of keeping the central system for the bulk of the whole home comfort, air flow, air quality and humidity control but also use one or more mini-splits to address areas where consumers want more direct control or where the central, ducted system is not keeping up. Our research articles will go into more detail about this and theories about why this is happening.

Myth #3 – Ductless mini-splits are more energy efficient because there are no air leaks in the ductwork.

Status: Mixed. Based on our research and the comments on the original article, I would say that there are definitely instances where poor or failing ductwork has led to major problems with central systems. No one can argue that the most efficient way to run an air conditioner is to turn it off. If you intend to turn off an entire mini-split zone for long periods, these systems will use less energy than a home that does not have zones that can be shut off. I am giving this a “mixed” rating due to the comments about people also using zones in ducted systems, in addition to comments about energy losses in the long line sets for mini-splits.

However, it has been shown that mini-split installation can also have serious “leaks” as long line sets on the outside of the house can pick up heat in the summer and lose heat in the winter. The result can be significantly higher energy costs than would be expected based upon the rated efficiency of the system.

Myth #4 – Ductless mini-splits provide superior comfort and quality of life.

Status: Mixed. Based on user feedback, I would have to say that for certain situations mini-splits can do a great job and at reasonable costs. However, it would also appear that for whole-home solutions in larger, U.S.-style homes, the hybrid approach of using a base central HVAC system along with some mini-splits for certain areas provides the best overall approach to both comfort and energy efficiency. Combining this hybrid approach with an automated duct zoning system for the main central HVAC would also improve the performance of the overall hybrid approach.

The Bottom Line on Ductless Mini-Splits

If you want to learn more about this topic, check out our first article on the survey of over 350 people who have purchased mini-splits in the past 1-5 years. In the meantime, we would encourage anyone in the market to get a few different quotes for each of the various system types that are available today and consider mixing and matching them to meet your unique needs. It is important to get multiple quotes not only to get the best price, but also to find the right contractor who can recommend the best equipment solutions for your situation, then install and service them well.

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96 thoughts on “Busting Myths on Ductless Mini-Splits: Part II

  1. Definitely a thumbs up answer. Thanks!

    A couple of follow up questions if possible.
    1) We had baseboard heat last year and installed a mitsubishi 17 seer 2 ton mini split ( by a professional) in the same location this year. Last year our heat bill over the month of Jan was $328, this year $307. The average temp over the month outdoors was pretty close. I think we have kept the living space a few degrees warmer this year, and last year we turned off the baseboard at night. It is not a hyperheat model. We leave the minisplit on overnight and drop the temp from 65 to 62 most nights, sometimes 61. Do you think we would do better turning the thing off at night like we did the baseboard heat last year? I thought we would come out a lot further ahead.

    • The SEER is just the AC efficiency. The HSPF is the heating efficiency.
      Which model is it? Is the indoor unit a wall unit or a ducted one?

  2. I really hope you can help me with this , although I do not know if anyone has actually done the real measurements. If not I will have to guess.
    But, if you turn off the mini split at night completely are you perhaps just as well off to use baseboard heat? And if the mini split is running pretty constantly at higher fan speeds when it is cold outside, is the efficiency similar to baseboard heat? It may depend on brand perhaps, and it’s start up mode from being off. I was thinking of Diakin.

    • Mitsubishi hyper heat units r between 300% and 500% efficient at 47*F ambient, compared to electric baseboard which is considered 100% efficient at any temp. At 5*F they r still around 200% efficient. A test was done in Minnesota in Jan? Of 2019 when it was -19*F n the Mitsubishi mini split was still over 100% efficient compared to electric baseboard.

  3. I have a fujitsui mini split system in a townhome rental we own. Had some issues with it this past year and told its obsolete, the indoor units are not made anymore and parts are hard to get. The unit was brand new in 2012 when the home was built. It’s hard to believe these units would only have a lifespan of 8-10 years! Also all the units are placed on interior walls of the unit. If I ever need to replace entire system, do I need to tear out all the drywall to replace existing lines or are most systems compatible with preexisting conduit/lines?

    • HI Robert,
      I am surprised that your fujitsu mini split system lasted only less than ten years. I have just googled up and here is what I found. “When adequately maintained, it’s estimated that most mini split ductless air conditioners last for about 20 years. This is far beyond the 12 to 15 years that most conventional systems last, so it’s fairly safe to assume that your mini split system will last longer than most other options.Dec 15, 2018.”
      Probably, it could have been due to lack of proper maintenance or improper installation. Without professional investigation, no one can be sure..

    • Which models are your Fujitsu units? I have found the updated outdoor unit is compatible with the old indoor if the refrigerant line size is still the same. There really isn’t much that changes, as far as basic function, with the indoor unit. The power requirement and the communication stays the same. The line sizes usually stay the same. Even from one brand to the next they are pretty much the same, so you could change brands in most cases, assuming the same size unit and the existing lines would be right.

      • Contractors like to only install units with a warranty, which is understandable. The manufacturers only warranty matching indoor and outdoor units, because that is how they were tested. And of course to save money. FYI, the new units are warranted up to 12 yrs now, so that tells you they must be quite reliable.

        • I have a feeling these units were probably older models when the home builder installed them in 2012. The problem I had was a leaking evaporator coil on the indoor unit ASU18CL. The total cost for diagnosis and repair ended up being almost $1400. The outdoor unit is an AOU 18 CL. Repairman told me he was lucky to find the part, and if he hadn’t I would have to replace both units since new indoor unit would not be compatible with outdoor one. It’s hard to believe the parts would not be available for a system that’s just eight years old!
          I’d hate to have to replace the entire system and take out sections of the dry wall to replace lines.
          I’m glad I just have a couple of wall units in my personal home…cheap and easy to replace when they go bad.

          • Yes, it does look like the ASU18CL/AOU18CL was discontinued in 2011. And the warranty was only 6 yrs on the compressor and 2 yrs on parts. So that may be partly why the parts were hard to get. But the refrigerant lines are the same size on the current model that is the closest to yours. So I have my doubts as to the new indoor model not being compatible with the old outdoor unit. I am a contractor that installs mini splits and I have found that some do not want to tell you everything. Always ask the contractor why the new unit is not compatible with the old, or why they cant do what you want. If they refuse to answer, get a second opinion.

  4. Has anyone used this system of mini splits in SW Florida? The outside unit would be facing west..which is in the sun for many hours. I’m worried about that.. Would it be a problem??
    Thanks for helping

    • Mini splits work pretty much anywhere, windy or not windy, although if it is very windy You may need a wind baffle which some manufacturers make to fit their units.

      • Sorry, you said sunny, not windy. they will work if sized correctly for the load. Check out what these folks have to offer. you can call them anytime and they will help you. loweryourheatingbill.com

        • BTW, their phone number is 866-401-6491. And come to think of it, it might be a good idea to put a small roof over the mini split.

  5. I found this blog to be very resourceful and well written. If anyone is looking for a great AC company, then you should check out https://www.palmairac.com/. I have used their services repeatedly and I am never disappointed!

  6. My SoCal desert home is a single story appx 1500 sq ft all electric abode. It was built in 1965 with two roof mount ac units ( each ducted to half of the house ) These units also provide the heat.
    For at least three months of the year, tempuratures are between 100-115 daily. The kitchen, living and dining rooms are fairly open to each other. Additionally, the living room and kitchen have walls of glass. The two bedrooms and baths comprise the enclosed spaces.
    My quandary is that both of my ac units are failing now and should be replaced. I can either replace both of my ac’s and associated duct work or install a mini split system.
    I bow to those with more knowledge and experience.
    Any thoughts would be greatly appreciated…

    • Here in PA there are an amazing amount of people heating/cooling their houses with one mini-split unit. What works the best is to put the unit on the side that the wind usually comes from, the natural draft gravitates cool or warm air to the opposite side of the house.
      But, having said that, we recommend to install the mini-split in the room that you use the most, and of course it works best to put a unit in each of the main rooms that you use. That is one thing nice about these units, you can mix and match indoor unit styles and you can install them as needed or as finances allow.
      We typically recommend single zone units because they are more efficient and the upfront cost is similar. Also, no matter what brand you install there is always the chance of the outdoor unit breaking down, so it is nice to have several compressors/outdoor units to rely on in case of a breakdown.
      So in other words I would highly recommend going the mini-split route since your main rooms are fairly open. As a general rule of thumb, figure 500 square ft or so per ton. (12,000 btu’s ) check out: https://villageofartisans.com/product/24000-btu-mrcool-olympus-e-star-series-20-5-seer-ductless-mini-split-inverter-air-conditioner-heat-pump-with-installation-kit-free-shipping-copy/ , you could put one of these at each end of the house, or something like that.

  7. Hi Robert,
    You have a good point, “the technology in mini splits is moving so fast there is a good possibility that in two or three years your model will be discontinued and make it tougher to find matching evaporators.” But I read elsewhere that mini split ductless, with good maintenance, will last between 15 to 20 years. If you look back for the last five to ten years, the technological improvement have been more in the area of energy efficiency. Of the discontinuation of the unit may create system incompatibility.
    Here is the link where I read about adding additional 3rd or 4th indoor unit at a later date. I have copied and pasted a specific part of the statement from it. The story heading is :


    “With Daikin’s Quad-Zone solution, any four rooms can be controlled individually. The 4MXS36RMVJU Quad-Zone is rated for 36,000 BTU Cooling Capacity and must be connected to a minimum of two indoor units. A third or fourth unit does not have to be added right away – one or both can always be added at a later date. The combined BTU ratings of the units chosen can total up to a maximum connected BTU rating of 48,000 BTUs”.

  8. I’ve switched my 1850sf home in Phoenix to mini splits. Because I purchase them in Mexico, they cost less than half what I’d pay online. I have the same amount of capacity the 2 year old 14seer system had, and FAR more comfort. The air handler in the old system was very noisy, and the ducts clearly lost a considerable amount of conditioned air. My electric bill was $81 last month, we had 110 degrees many days and the house was kept at 75. The bill to run the old system in June was about $200, even with 3.8kW of solar. That includes fridge, ice machine, attic fan, heat pump water heater, pool pump 10 hours each night… My experience has been excellent and I will never switch back.

  9. Using a state certified HVAC Installer, I am planning to install a Daikin ductless mini split multizone system in my house of four rooms. The overall goal is to have one indoor air handler in each room all connected to an outside multizone unit with a maximum of four zones capacity. Due to financial reason, the temporary plan is to install only two indoor air handlers with each unit going into one room.
    Over the next two to three years depending on when financing gets better, I will order two matching Daikin brand of additional indoor air handlers to be placed each one into the two remaining rooms. They will be connected to the same outdoor multizone unit that I had installed. I understand each zone operates independently. Is this really technically feasible? If not, why not? I am presently based in Johnstown, PA 15904.
    An HVAC pro visited my house and shared that this approach is not permitted by the manufacturer. The reason provided is that, they system must be installed at once with match or compatible indoor air handlers. He also added that when it’s a right time to add on, he would have install two additional air handlers connected to another second outdoor multi zone unit. I told him that this doe make sense.
    He offered option of install all four indoor air handlers at once and connecting them to the one outdoor unit. The contractor also cited problem with refrigerant flow issue if all the four indoor units are not installed at the same time. I have great respect for the contractor’s option. Its was a surprise. Has anyone ever faced similar issue?
    I am really confused. Look at it this way. If you install four indoor air handlers, one in each room but them you shut off the two indoor air handlers in two unoccupied rooms, you would end up running only two rooms with two air indoor air handlers. That is what the manufacturers told us in their adverts, that saving benefit of using Mult split ductless system.
    How would this different any way if I only install two indoor units then add additional two more units in two rooms for about two to three years later? Cannot really an outdoor Mult zone unit power two indoor air handlers and again, adjust it to power additional two more indoor air handlers when connected to it at a later date?.

    • Not sure about installing just two evaporators it might be ok ask the manufacturer to know for sure. If I were you I would install all single zone units or a dual zone then later another dual zone. My reasoning is if the one compressor on the four zone system goes out you have no a/c period and from what I have noticed is the price of 2 single zone units is about the same as a two zone not sure about four zone cost. Also the technology in mini splits is moving so fast there is a good possibility that in two or three years your model will be discontinued and make it tougher to find matching evaporators.

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