Busting Four Myths About Ductless Mini-Splits

Over the past few years we have all observed the U.S. HVAC industry’s fascination with ductless “mini-split” air conditioning systems in the U.S. Recent HVAC trade shows have been crowded with OEM’s promoting this “new” way of providing home comfort. National advertising and media/public relations tactics would make us think it is just a matter of time before we all say goodbye to our central AC systems and get with the rest of the world (i.e. Japan, China and Europe) in the way we keep our homes and businesses cool and comfortable.

The article below was written in 2013. We have updated information for homeowners busting myths about ductless mini split systems, outlining what to consider when choosing a new HVAC system, as well as recommendations on when a ductless system might be right for your space.

The AC & Heating Connect staff has also conducted research on ductless systems and uncovered some facts that might be of interest to contractors and distributors as the industry plans for the future growth of this segment.

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

Industry statistics would not support this statement. While the ductless segment has posted impressive growth rates in the U.S. since 2005, the growth rates have been slowing recently and the largest ductless segment (small, single evaporator systems) have not grown at all since 2010. These sales remain stable at about 260,000 units per year, or only about 4% of total unitary AC shipments. Some larger VRF-style commercial systems continue to grow at higher rates, but their numbers in the U.S. remain small at only 28,000 units per year.

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

The current economic facts about ductless simply do not support this claim. The installed costs associated with using mini-splits to cool and heat an average 2,000 square foot home with ductless mini-splits would cost almost three times the cost of simply replacing your central AC system with another ducted system. Even in a home where you had to provide new ductwork for the central system, you could still expect to spend about 50% less on a typical central AC system installation versus the more expensive ductless options.

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

What people who make this claim fail to mention is that in ducted homes, which have poorly installed and leaking air ducts, the conditioned air is probably leaking out of the ductwork but it is going into the conditioned space somewhere and helping to keep the house cool. In those cases the cooling energy is really not lost to the homeowner. While mini-splits don’t have duct losses, they do have other losses. Instead of distributing conditioned air throughout the home, mini-splits distribute refrigerant. In many cases these refrigerant lines are run outside the conditioned space and in these cases there are thermal losses associated with energy transferring from those lines to the space outside the home. A legitimate energy loss occurs when you are heating or cooling your backyard with mini-split refrigerant lines (see photo below). Duct leaks that leak into the conditioned space are not really losses at all unless they escape to an unconditioned space. The other claim made by mini-split advocates is that they provide energy saving due to “zoning” or shutting off energy use in unoccupied rooms. What they fail to mention is there are other modern methods to zone off rooms besides using ductless methods. There are many ways to achieve zoning.

*Discover the updated status of this myth here.

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

The problems with ductless cooling are not well understood by many U.S. consumers since they are relatively new to this region. The typical comfort experience with mini-split systems could provide a real challenge for American consumers who are used to central AC systems with good airflow exchange, filtration and humidity control. Cold and hot spots are also common with ductless systems due to the spacing of the indoor units. In addition, there are concerns about US homeowners’ reaction to the aesthetic and architectural impact of having air conditioning systems hanging on several interior walls and having refrigerant lines running to various rooms on the sides of their homes. Before installing a ductless system with multiple evaporating units it might be good to show your customer some photographs of some of your previous mini-split installations so they have proper expectations.

*Discover the updated status of this myth here.

The Bottom Line on Ductless Mini-Split Systems

Ductless mini-split systems are ideal for spot cooling situations in homes and businesses where ductwork is either not available or difficult to install. It is important for contractors to have these systems in their portfolio of HVAC solutions for certain situations and learning where and when to recommend them is essential. Knowing the facts associated with these new systems is also essential to avoiding problems when customers are surprised by the many “myths” about this technology.

The myths in this article have been reevaluated. You can find the updated article here.

What has your experience been with ductless mini-splits? Leave us a comment below!

A typical indoor wall-mounted, evaporating unit – usually one per room are required to minimize hot and cold spots.

A typical U.S. style home is shown here with a retrofit mini-split system. Notice the exterior line sets and condensate drains. Thermal losses could be expected from the vertical, external refrigerant lines and these might cause the system to have trouble keeping up on really hot days. Also, notice that the window-room air conditioners have not yet been removed. A close up photo of the house above, showing the external refrigerant lines and a condensate drain line. Ductless mini-split systems are often used to cool room additions as shown here in the garage area. A large, high rise apartment building is shown, using many mini-split systems – one or more per apartment.A large, urban apartment building is shown, using mini-split systems – one or more per apartment.


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369 thoughts on “Busting Four Myths About Ductless Mini-Splits

  1. We have central AC but the unit is too small and there is no room for a bigger one. The master is 10-20 hotter then the rest of the house. We are trying to decide if we should do a mini split or do an in the wall AC unit. I can’t find anything that speaks plainly about the cost to run either or. We live in TX and it’s hot most of the time. It just seems crazy to spend 2,000+ on cooling a 400sq space but if we would spend that much in electricity with a wall unit then it makes sense.

    • Hi Lisa, Here are a few answers to your questions. The efficiency or energy usage is usually designated by a “SEER” rating (Seasonal Energy Efficiency Ratio) which should be shown on a label on the outside of the unit. The higher the SEER, the better the efficiency and the less energy you will be using for given capacity setting.

      The room that is warm is probably at the end of ductwork and further away from your indoor cooling unit (evap coil and air handler). By the time the conditioned air gets to that room it may have already been warmed up and lost its cooling capacity. You might look at the duct line that is leading to that room to inspect for air leaks or you might try adding some insulation to preserve the cooling capacity. You can also look at all the other vents in the house that are closer to that unit and maybe close them a bit to direct more cool air to the room that is not getting enough cool air.

      If none of that works and you are sure your system is running properly (i.e. it is cooling the other rooms well, etc) then it makes sense to add a small system to that room to keep it cool. The lowest cost and easiest to install would be a window AC unit. This might address your problem but you would have to give up your window to do it. These are not usually very energy efficient but they are small enough that they do not use much energy anyway and might meet your needs.

      Through the wall units are a lot like window units except you don’t give up the window – but you do have to cut a hole in your wall. You might still have issues with noise like you would with a window unit since you have the whole unit right next to you instead of separated like your central system or a mini-split.

      Mini-splits are available with very high SEER efficiencies and have many benefits – outdoor unit is separate so it can be very quiet. They usually feature variable speed capability so this might address any humidity or airflow issues.

      if your central system is pretty old (over 14-16 years) you might consider just replacing it and adding some duct work to the room that is getting warm. If it is newer than that then adding a smaller unit to that space might work for you. Hope this helps.

  2. Planning to build 950 sf cabin – 2bdrm/2bth, 12×24 equipment basement with joist floor above, rest of floor slab-on-grade with in-floor heating. This is in Central Minnesota. Due to lake-shore building restrictions, we are stuck with current footprint. We will raze and rebuild from scratch, using footings buried 5′ deep. Roof is very low pitch – 2:12 is all we can have. Thought was to use mini-split with ceiling cassettes – one in kitchen-living room area, one small one in a 10×10 bedroom, and one in larger bedroom with short hidden ducts to the 2 small adjacent bathrooms. With heat pump outside, plan is to run line set from unit into 2×6 wall and up to attic – from there run to the 3 cassettes. Attic will be conditioned space, as roof will be insulated – known as “hot roof” in the area. Thinking a 12k-btu for the main, a 6k-btu for small bedroom, maybe 8k-btu for master bedroom with supplemental in-attic ducts to the 2 bathrooms which are both adjacent to master bedroom.
    Any thoughts??

    • Hi Larry, That should work. If you want to be certain on the capacity you might call a contractor who can check to make sure you have selected the right sizes considering things like level of insulation, shade, windows and doors, etc. Another thought might be to have another heating source for the coldest part of the season as the electric based heat pumps (all of them – central or mini-splits) are not very efficient when the ambient temperature gets below about 15F. This is called a “dual fuel” approach when you get something other than electric based heating for the really cold periods or when electric rates are high etc.

  3. Appreciate the original poster allowing all these comments even though they aren’t all flattering. It’s good to hear all the pros and cons we can. Thanks

    • Thanks Red! I wrote the original post back in 2013 just to get some dialogue going. At the time there was a lot of industry buzz about ductless mini-splits taking over the world (or at least every home in the US…) and I just wanted to present both sides of the story as to where this technology makes the most sense.

      I think a lot of people can now at least see all the pros and cons. As long as the visitor posts are not offensive to our readers or are violating our policies about ads, etc we usually leave most comments stand on their own. Thanks for visiting our site!

  4. I am really confused here. I think i found a reputable dealer through our local PUD. I have had multiple quotes. The ductless came in 1K less than a furnace/heatpump combination. I have a 1400sq foot manufactured home. He recommended one 1800 btu for the living room/dining room/kitchen space (all open); 900 but for the master bedroom; and 600 btu for the smaller guest room. This is $7400.00 (with rebates, etc). I have asthma so i thought maybe going ductless would be better as far as cleaner air. He told me that the filters can be washed and re-used. Has anyone heard of this? I am having a hard time with the “paradigm shift”.

    • Do yourself a favor and get the furnace and heat pump setup. I gaurantee if you get a reputable contractor to install it will last a lot longer than a mini split. Also parts will be a lot easier to get when a repair is needed!

    • Suzan: while I’ve only had my mini splits for 2 months I’ve now had them through the heat of the Summer. While I don’t have allergies, etc….one (of many) reasons I sold myself on mini splits was the ductless feature. YES! Was a huge paradigm shift for me as well. I have a 100 year old home and architecturally speaking, didn’t want to detract from the house. I’m finicky as all get out and they don’t bother me. That was one paradigm shift.

      I did have them quote my 2nd floor fully ducted and it was mildly more expensive. I kept reading and reading and reading and decided to go with ductless. They were able to hide all but one ‘run’ outside so no eye sores there. As I mentioned, the interior – doesn’t bother me at all like I thought it might.

      Instead, what I have is 5 zones in my 2,700 square foot house that I can cool (or heat) specific to each rooms demands. A south western facing room on the 2nd floor needs set differently than a northeastern facing room on the first floor. I can adjust accordingly in all five zones.

      The thoughts of looking inside ductwork after even a year of use sort of grossed me out. Not to mention 2 yrs, 3 yrs down the road. Fact of matter is how many people do you know with ducted systems that have them cleaned? Then being the skeptic that I am, are they really clean? Each of the Mitsubishi ductless units I have has three filters. I don’t remember exactly what each does but there is a larger one you remove, rinse, let dry and replace. Then there’s two smaller filters that get replaced roughly annually.

      I’m still new to the whole mini split idea as well but I did it and granted it’s only been two months but I’m not sorry.

      (I had started documenting my thoughts and experience on this site because I couldn’t find a ton of information. I wanted to help others contemplating as I did. And I couldn’t believe the original authors article. It was so slanted against)

      • Thank you, Eric!! This article had me a tad worried but now, I’m not. We are scheduled to have one minisplit unit installed this month in our den. I think we’ve made the right choice.

    • Ductless mini-splits are definitely not the best option in all situations. For a normal suburban house say four bedroom two bath, 2200sq ft I would definitely get central heat & air. But if your living situation is different, especially smaller or open floor plan they can be great and yes super efficient. I live in a small one bedroom house with pretty open floor plan about 750 to 800 sq ft and have only one mitsubishi mini-split and I like it cold. Yesterday it was 108 degrees and my 10 year old unit was easily chilling my place to 61 degrees and wasn’t even turned up half way. The thing is amazing. Costs about 25 bucks a month in electricity. You must maintain it correctly which can be a little difficult if done right but also cheap no new parts are ever needed and filters are reusable. The entire cost of maintenance is just cleaning supplies, coil cleaner mostly and the it. I’m very happy with my Mitsubishi.

  5. I am a hvac contractor and I installed 2 multi head Fujitsu systems on a 3400 sqft spray foamed house in arkansas and so far there electric bill this summer has been $100 a month.

  6. We installed two mitsubishi mr slim units in our barndominium here in south texas in 2015. It is a small barndominium and it is insulated very well but these things are still amazing. I didn’t run them that much in the winter for heat but in the summers i keep them at 64-65 inside and on dehumidify mode, my wife swears we can hang meat in here. 😉
    I am starting the dream house in 3 months and contemplating using mini splits we like them so much…

    also, if you want to get the most out of the cooling/dehumidify mode you should run it on whisper mode. This causes the air to pass over the coil longer which is key to dehumidifying.

    • I am planning to build a small 1150 square foot barndominium soon. I want to do the mini split system but I’m told it’s just too expensive. A builder of barndominiums tell me this and then I called a AC Service close by and they said it was over $5,000 a piece per unit. Then I noticed I can buy at Home Depot for around 1700 and anyone with some electrical and or Plumbing Service can actually install. I’m so confused. But this is what I want and I wish I could find someone here in South Texas to do it. Thank you for your input.

      • Yes you can find mini splits at Home Depot. You can find a or ofmthings at Home Depot if you trust their contractors. That will be your call.

        I had a “diamond” hvac installer (Mitsubishi talk) do the work for me nuts to bolts. Total of 5 areas (units) and cost about $21k and change. This did not include the upgrade I had to make to my electric panel). So you can do,the math.

        Here’s why I’d only work with a qualified installer:
        1. They sized each unit appropriately for the room size, space and location of each room. They take things into consideration like first or second level, room size, exposire to weather, etc…
        2. They’ve done this before. I have an old home and did not want someone drilling holes in my house that didn’t know what the are doing. I also wanted someone to use their head and hide as much of the our door lines as possible.
        3. I wanted someone who could give an honest opinion for the location of each unit.
        4. Cost is important. I had quote from two diamond installers. I chose the more expensive because I worked with them before and they seemed more ‘into’ my concerns and questions. They didn’t pressure anything.
        5. They have a ‘hotline’ right in to Mitsubishi
        6. They’ve been responsive to all my questions and follow up
        7. Extended warranty on parts

        There could be many reasons why something cost more or less. These area few that made me feel comfortable making the decision that I did. And these guys gotta pay people. I had a crew of 3-5 people here for a week straight not to mention some follow up.

  7. I am in central PA and always used window units.I Got older and tired of lifting them so I contacted several contractors on mini split installations. Most of them tried to talk me into central air and was quoted 12.000 to install because I needed ducting also. They were really against minisplits. Finally I got a contractor to install two 12k mini units and that was the best move I could have made at 4,600 dollars complete. Going on five years now and absolutely love them. I get them serviced every year and the evaporator squirrel fan is critically important that it gets cleaned annually or performance will go way down so I clean IT myself. I realized the contractor was not cleaning that fan even though I paid for it. You really have to watch these heating and cooling guys, many will take shortcuts and many will mislead you on what you need to install. Its a nasty industry full of shady technicians. DO YOUR HOMEWORK so you can decide if you have an honest contractor.

  8. I have installed pioneer brand in a 1300 sq ft rental house. 1 in living room and 1 in each bedroom. I keep asking tenants about their electric bill, highest bill in the last 2 years was $140. Cost for each unit was around $600. I’m a technical person and my husband is a mechanical person, so we were able to install ourselves. No problems so far. The remotes that came with them are pretty cheap, one year when changing from cool to heat mode, it didn’t want to go to heat. But a quick search and found out to take the batteries out of the remote for a few seconds. Did that and was able to swap to heat mode. They have been a great investment and tenants are very happy. Not nearly as expensive as what’s been mentioned here.

  9. We are researching this now as our current standard AC will cost 2,000 to do a quick fix but is still R22 refrigerant which we were told is won’t be available after the yr 2020 OR pay $8000 to upgrade to a 410 system.. Our unit is 11 yrs old so we will just be replacing with new one way or the other.. House is 1340 sq ft and not open floor plan with 3 bedrooms.. Wanting to hear if the refrigerant used is R22 in these and if any of you have similar sized home and how you like the system etc.. Thanks to any and all answeres

    • These are 410A coolant. Most new units, split or central, are 410. If someone is trying to sell you R22, I’d avoid them.

  10. Eric, I installed an LG 12000 btu (with seer 21.5 and hspf of 11.0 mini-split heatpump) in a 400 sq.ft. cabin/cottage that I had insulated well. It was all I needed to heat the cottage over this past winter. It performed extremely well was super quiet ( never needed sleep mode) and it heated that space for an average cost of 90 per month ( estimated since I used a 150 watt heat lamp in a very well insulated crawl space to insure water pipes etc were protected. I also installed an outlet in the cottage so I could use a garge heater as back up but I never needed it since this past winter was a little warmer than most.
    One thing about heat pumps though that it is important to note. If you oversize the unit so that it short cycles (ie doesn’t run the defrost cycle consistantly) then the performance will suffer… better to go slightly undersized than over sized.
    My experience with LG was so satisfying that I am installing them in my new 1600 sq ft cottage.

    • Thank you for the comment about making sure the defrost cycle runs sufficiently. That is the first time I have heard that and it is important.

  11. I installed a Mitsu mini HP in a problem area of my home last year. Kind of a stranded room, west side. We built 28 years ago, open plan 3 floors. Difficult to get good ducts to that room. Verdict, wow, amazing! I can’t tell you exact power use aside from stated 31 SEER but that thing put out heat ALL winter, and cools beautifully in the summer. So impressed, I am starting a reno of a 1951 Cape Cod shortly. It has 7′ ceilings in bsmt made lower by ductwork. It is complete gut and redo with 2nd floor expansion. I’m trying to figure out how to do whole project without central HVAC, only splits and a few strategic air movers. All new windows and siding so maybe I can put exterior pipes into walls, or build small exterior chases into plan. Any advice appreciated. Fully open mind here…..

  12. We are having two 5 unit systems installed with all the piping and drains inside conveniently placed closets that run down the sides of our chimneys.

    Yes it is more expensive then traditional, but like my father always said “you get what you pay for”
    It’s way more efficient, way better then window units, way less work the. A traditional system
    It gives every room custom temperature control-awesome compared to traditional systems.

    I’m not sure where this guy got his info from, but I completely disagree with it.

  13. You need a new job, perhaps join the ductless mini split industry for a better paying job that is not sad like this one.

  14. I’m having 5 mini splits installed in my home the week of 6/19/2017. One mr slim ducted and zoned for the kitchen and another mini split on the wall on the opposite side of the house. Then one unit each in each of three bedrooms. I have an almost 100 year old home which is about 2700 sq ft.

    This IS NOT inexpensive. First I need to have my electric panel upgraded to 200 amp and then the installation. Total will be around $25K. I’m in Cleveland Ohio and had other estimates and they were on par.

    I did a ton of research and hope it doesn’t fail me because as I said, this isn’t cheap. Only con I personally have for mini split is what most say; the looks. Over time, if they bother me, I will find a way to camoflouge somewhat with shelving, draperies, etc….I’ve vacationed plenty in the caribbean and it’s pretty much what they use. I loved them and didn’t notice them so much on the walls.

    The pros, as I understand them, are: efficiency, zoning, no duct work and germs/bacteria, no surging power on and off, some pretty cool technology (i see), heat option if ever needed, inverter technology to slow or speed dump the fans and more.

    I know I sound like a brainwashed commercial and I am praying I’m making the right choice. I’ve googled, chatted, visited YouTube, etc……which has lead me to my decision to use these mini splits. Thus far, just from my research phase, my only draw back (and it’s substantial) could be how they look.

    Keep your fingers crossed for me.

    • Update to my post dated 6/9/17: (I’m trying to detail my personal experience because I couldn’t find all the info when I was researching)

      Day four of installation. Maybe I’m lucky but the install team is doing a great job. Almost done. They are hiding what they can, the best they can, outside the house by running the line hide under eaves where they can. They are spray painting it to match the dark brown trim color of my Tudor. They’ve listened to me and have taken my suggestions with my ‘always’ caveat of ‘as long as it doesn’t interfere with operation and maintenance’.

      They are ducting the kitchen in the toe kick with a handler on the basement ceiling. This unit will have a conventional thermostat (vs remote) and will tie in with boiler heat and use the mini split as the secondary heat source if ever needed. That was my call since today gas is cheaper than electric). They did an amazing job cutting the return under the radiator in my dining room (perfectly centered and set back as far as it could) and I already ordered an iron grille cover to dress that up a little.

      Was about 90 degrees here yesterday and the unit in master bedroom was connected and ready to go. Granted, I’m coming from window units, but these things are so quiet I had to put my hand in front of it to know it was running. At higher fan speeds you hear a bit more but it was still quiet and imo there’s no reason I’d need to run high fan speed for more than a few minutes. I even put this 15k but unit to the test and slept with bedroom door open and I was comfortable all night.
      As was the master bath this a.m.

      Provided these suckers are as reliable and as energy efficient as I think and they do as good as an install as I think they are my house is going to be extremely comfortable and quiet. Checks I’m happily writing.

      Now I need to master the remote.

      • Eric, do you care to share your selection of mini-split vendor after all of your research? I have just begun to look into mini-split systems for my 450 sqft lake cabin and would appreciate any advice and manufacturer selection info. Thanks!

        • Brian, I went with Mitsubishi. One contractor quoted another manuf (American standard) only after I asked. His first quote was Mitsubishi, and as I stated earlier, I was surprised how expensive this endeavor was when I first started investigating. When other estimate/s came in on par I realized it is what it is.

          Granted, it’s probably the ‘big’ guy who has the marketing $$$ but I felt comfortable since Mitsubishi is the one I could find ‘lots’ of information about.

          From what I researched, and it makes sense, installation is as important as the install so if going with Mitsubishi I think you’d want to look into the Diamond dealers if you choose Mitsubishi. The warranty is 10 (maybe it was 12) years for parts.

          Hope this helps a bit

          • Eric
            We live in Georgia and are looking to heat and cook basement. It’s small…600 to 800 square feet with doors. Any suggestions on what to ask a manufacturer for to cover all rooms? I would der if there’s one unit that can be used on all or most rooms. Thank you

          • Hi Shea

            I’m not a contractor but can share my experience. There are units that can cover the square footage itself but then the question is will one unit be enough to make each room comfortable. Certainly the room the unit is installed in will be comfortable and the cooler air should eventually make it into the other rooms (to some degree) when the doors are open. One of my contractors suggested installing one larger unit in one of my bedrooms and nothing in another. He said ‘on a bad day it should be comfortable enough.’ Another contractor suggested installing two units (each smaller in btus) in each room rather than one and that’s what I did.

            My contractor measured each room and took into consideration where the room is located (1st floor vs 2nd and north, south, etc exposure). He also had some calculation assuming it was 90 outside and I’d wanna run it at 69 degrees. That’s how he sized my units.

            This is why a good contractor will be helpful.

  15. nothing made today is made to fix. so you take your chances with quality.but installing minisplits is cheaper than ducted. where he gets 3x more is beyond me. with a/c cooling mode the omnly hot and cold spots are due to elevation levels in a home. cool air is like water and will easily disperse throughout even from 1 location. upstairs should always be blocked at top of stairs to hold the air up. as bfar as looks. look for the backsides of closets or use a partion. easier than ya think. and the duct loss thing were that doesnt lose efficiency is crazy. air lost has to be made up and the high ambient of an attic kills any efficiency you may have thought you had. attic installations and roof top units should be illegal.

    • I completely agree with Greg. The loss due to bad ducts makes the air leak out in the attic which should not be cooled. Also, the closet real estate space lost for Central Air also isn’t considered in this article. Neither is the fact that you can have a “ducted” ductless system that works almost just like central air but still costs less to install.

    • Hi. So I could use one unit for 4 rooms, especially for cooling? InGA, we don’t use much heat anyway…also, have you heard of Alpine mini splits? There Blue Ridge model is only around 500.00. No middleman!

      • there are many minisplits that offer 4-zone applications. keep in mind that the smallest usually is 7-9000 btu/head. that will do a very good sized room. everyone has there own calculations but i use 600 sq ft/12,000 btu. most often you can get by comfortably with 1 head/floor. and i still cant imagine it being o.k. to have leaky duct. and like i said before, duct installed in an unconditioned space is defeating your own purpose. ive had to do it a few times but the kind of people that want it done certainly deserve it.

        • You can’t really use the 600 square foot per ton rule. It might get close then again it might not. The only way to get a true idea is to do a Manual J. For example, I just did a manual J on a SIP panel home in the Kansas City area. It’s 1,300 sf and the manual J called for 9000btu. The house is a super high efficiency home. It just depends on the house.

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