Four Myths About Ductless Mini-Splits

Understanding the Pros & Cons of Ductless Mini-Split AC Systems

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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529 thoughts on “Four Myths About Ductless Mini-Splits

  1. Awesome ideas. You corrected the wrong information I have regarding ductless mini splits. Please continue your doing, you’ve been a great a help. Thank you so much.

  2. We are building a “Tiny House” apx 500 sq ft. We are planning on installing a 12,000btu mini split. I thought the mini split vs a window air conditioner would be more cost effective? I know window air conditioners cost a fortune to run. Help me out. Am I wrong?

  3. We would like to use mini ductless system in home new 2663 square feet with 12 rooms including bathroom, 3 bedroom 1 media rm , utility long halal with closet and study a big living and dinning rm kitchen combination open do you think mini split will work over reg hvac

    • Can a mini split be used for just one large bedroom which doesn’t have a big enough cold air return to keep the room cold?? And is so, approximately how much would that cost?

  4. I’ve spent several months in Japan, especially in Kyoto–never during summer, but definitely during freezing temperatures. I agree that the cold there is colder than the cold here. But I’ve never had a problem keeping warm with a ductless mini-split there, even though I’ve always had them in 100-yr old machiyas (traditional wooden Japanese homes without insulation). I’ve never had to dress in heavy clothing to keep warm once the system warmed the place up. I agree that such systems aren’t for every home. But to trash them completely is unwarranted in my opinion.

    • This site is just lobbyist BS setup by the traditional markets (Goodman, Trane, etc) to keep people away from the easier and cheaper solution of ductless mini splits. Oh yeah…and they installer industry because about anyone can install these.

  5. I have no problem with my interior unit’s configuration. Like I said its a lot better than cutting holes in my heart pine floor in every room and doesnt look as bad as the huge return ducts on most central systems. Plus I dont have to buy new filters every month. Takes five minutes to vacuum the reusable units. Want to see what mine look like? Google LG 18,000 Mini Splits.
    For those of you who continue to demean the Mini Splits, I have a few words; “Its impossible to defend an indefensible position!’

  6. I’m no expert, but it sounds to me like this guy is trying hard to make a good thing sound bad. Rather then upgrade his business and grow with new technology, he’d rather stick to the same old expensive system to make more money. After all, the old system constantly needs costly repairs. Not so much so with the mini split system.

    • “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.”

      I have two 18,000 BTU LG mini splits, one upstairs and one down stairs, so where are “The current economic facts”?

      What is really going to be grand is when they start selling Mini Splits without the transformer to convert from ACV to DCV and we can run our units strictly from solar without going through an inverter. Its coming! You heard it here first!

      • is it cheaper to put in a mini-split AC system in 5 rooms than central air I use window and wall now and have no duct work at all

        • Ducts are totally gross especially if you have allergies. My Dad used to hire a company to come and vacuum out our ducts every few years. they had this cloth bag and it was probably 40 feet long with a huge vacuum motor on it. When they put it on the curb at the edge of the street it looked like the Hindenburg. The bag would be clean on the outside when they began but just the junk that got through the pores in the bag it would turn dark when they were finished. People just dont realize they grow all kinds of virus, bacteria and mold spores. I still use an ozone machine in my home. I had to build my first one about 30 years ago. When they first came out they were like $650.00! Now you can get a really good one for around $125.00. I think big pharma has gotten the Feds to write a caution on them but hey, they kill all the bugs and you just dont have any communicable disease germs anywhere in your home. Dangerous? Mine has been running 24/7 for over 30 years and Im healthy as a mule at age 77! Its those days when I feel 19 that things really get scary! LMAO

  7. I install hundreds of ductless heat pumps. Many as entire home systems. I remove ductwork made of fiberglass that is so filthy and mold infested the last thought on anyone’s mind would be to use this to circulate the air we breathe. Ductless inverters are always the right size on any given day as opposed to central which is only correctly sized on a design day. Each unit is its own zone allowing for different temperatures in different rooms. Duct loss is non existent as refrigeration effect takes place in the room being served. Fractional amperage blowers that allow for constant circulation at a minimum cost as compared to a central unit that will use 14 amps on a 4 ton blower just to equalize temps on separate floors. Ductless Heat pump water systems are quite popular in Europe where hydronic systems use water below 120 and they also produce domestic hot water. Unfortunately US systems require hotter water. So far Daiken is the only one to introduce this tech to the US with their Altherma unit. Your article is so wrong in so many ways I really don’t know where to start. You don’t need to be a genius to understand the filth that is fiberglass duct.

    • Anthony Spandafora, you are one in a million. You will still be going strong when all the rest are still trying to hide the truth about the effectiveness and efficiency of Mini Splits.
      It is tough to admit that something you have been doing for 50 years is wrong or has been trumped. But the biggest reason they wont admit is because of their bottom line. If the product is less expensive, then they cant make the kind of money they are used to. Solution to that problem is to put in more systems! You got it nailed buddy. Thanks for your honesty and your post. You are one of the good guys!

      • Woah! THANK you for saying what we all know but don’t have quite the experience to articulate so precisely. I don’t understand why AC companies don’t simply add ductless mini splits to their services offered. I got a quote for three in my 1250 square foot home and it was over $6000. I’m looking into buying one on the internet and having my contractors install it for WAY less. I’ve seen DIY videos online and if it came down to it, I’d even do it with a friend. (I worked in renovations for several years.) Do you have any suggestions as to which brand to purchase? Thank you for your excellent information!

        • I can provide 2 electric bills. 2017 with Central Air and 2018 with MiniSplits.
          2017 Average Electric bill in the summer was $260
          2018 Ave Electric bill is $170 in the summer and the house was ALWAYS at 68 degrees. With my central air unit, it struggled on hot days.
          2019 (this summer) will be even less because we insulated.

          Mini Splits are the future.

  8. Just had my 1600ft house installed with 5 zone mini split system in Phoenix , were it regularly reaches 120F in the summer, cooling is far superior to a ducted system whisper quiet, cleaner air is circulated, ventilation is far superior, can set different rooms to different temperatures and different fans speeds, using about 25% of the power to cool. It cost about 10,000$ installed which is the same as what it would cost to get a new central AC unit and new Ducting. Now I am Saving about 1,000$ a year it will eventually pay for itself. we had to do it for health reasons ducts collects dust, fungus, rust, and bacteria (despite having yearly duct cleanings) Me and my wife were both experiencing a chronic cough from the ducted system.

    • “health reasons ducts collect fungus, rust, and bacteria” This also happens in hot summers to car AC units. Dollar stores carry pet stain remover which has an active enzyme that eats blood, fecies, etc. The enzyme also eats fungus and bacteria. Directions:
      Turn on car AC. Spray product into air intake grates below windshield wipers. Let run a bit to filter thru system. Works great.

  9. As a custom home builder/renovator I’ve used the mini splits numerous times. they work well in bonus rooms that have a roof system exposed underside or vaulted ceiling. We always use a radiant barrier roof sheathing to keep the heat down in the summer in this 100 degree humid environment. I’ve also used them in room additions or small mountain cabins or sunrooms.
    I can’t imagine trying to condition a whole house with minisplits.

    • My design criteria over 30 years ago never used radiant barrier. I know a number of companies who installed hundreds of homes with the material. I was always studying the effects of different types of insulation. Its better than nothing if used properly. If you are in an area that uses heat more than cooling, the aluminum should go down. In hot climates the aluminum should go up. Now, here is the ultimate solution I came up with after decades of experimentation; I normally build with block or poured reinforced concrete. On the outside of the wall, and the roof is the same, I install stringers and inside the stringers is 3″ foam, vertically, which is cut to size for me by the manufacturer. On the outside of that is 1″ foam, horizontally with aluminum on the outside. Then stucco wire nailed to the stringers. Then three coats of real stucco. THERE ARE NO AIR GAPS in this type of construction and with both the walls and roof insulated in the same manner you have the most effective insulation possible. Ive even built with concrete roofs! If you stucco the soffit and facia, there is never any outside maintenance! I always use steel roofing. Light colors in warm climate and darker colors in cool climates. That, my friend is bulletproof and almost 100% storm proof! I met a insulation dealer from Phoenix who told me that extra batting from jobs went into the attic of his own house. It was an “L” shaped house and they started at one end and filled three or four feet with fiberglass insulation. He noticed the portion with the extra fiberglass caused the HVAC unit to run all night in summers! It was pulling the heat that had been stored in the fiberglass through the ceiling, technically, in opposition to what one would think, it was ‘over insulated’. Now, no matter what the ‘tests’ show on fiberglass bats vs Styrofoam, let me just give you one example: You buy a cup of coffee in a Styrofoam cup and the temperature is around 200 degrees. The cup is about 1/8″ thick. CAN YOU FEEL THE HEAT? Its funny one builder said, “Sam was building houses he thought he could heat with a candle. He was mistaken. It took two candles! Sir, this is where it all begins and ends. Hope you get my drift.

      • As a footnote, my personal residence has 3500 ft sq and two mini splits, one up and one down, both 18,000 LG 21.5 SEER units which can easily be powered by solar panels. I wouldnt change a thing. At the risk of repeating myself, basic thermodynamics tells us that heat is attracted to cool so you really dont need a ‘central blower’ to circulate the conditioned air which uses as much energy in the blower than the entire mini split uses!

        • Sam,
          In our last home, the central AC unit dripped water from condensation into the furnace. A pump was installed, we checked & cleaned lines – still everything rusted out.
          Now we are researching mini splits. You are a wealth of knowledge. Any suggestions for best efficiency using mini splits in our current home?
          Located in Michigan, small ranch style, stick built, vinyl sided, 6″ thick walls, blown in insulation, asphalt roof (to be replaced with steel roof).
          Thank you for your opinion,
          Jim & Gail

          • Jim and Gail, thanks for your question. For myself or anyone to advise technically I would almost have to see the house. With that said. As most older ranch style homes, the rooms are usually small and lots of them rather than wide open spaces. This requires some thought. In your situation, one story, I would first try to figure a way to use maybe two units and get a cross flow. An “L” works pretty good. Say you have a long hallway, place one at the rear terminus of the hallway and if you then have a living dining area with say the dining area being separate from the hall area, then I would put the second one there blowing in the opposite direction. Hopefully that one would also into the kitchen and if the kitchen happens to be open to the back of the hallway that would be ideal. Send me some more information if you like and I will try to narrow it down for you. If you are interested in privacy, more or less, start with a louvered door in the bathroom (s) be sure to have the louvers separated because some are not. And place the louvers so you can see down out of the bathroom but not into the bathroom. Any other rooms needing extra circulation may require the same treatment. The bathroom with a powered vent will pull the heated or cooled air into the bathroom. I dont even use mine and dont have a louvered door. Food for thought!

  10. Mini splits are a great innovation…..BUT….the designers need serious help with the aesthetics of the exposed equipment hanging on the walllije a narrow white “ mini refrigerator” . Many are reluctant to destroy the aesthetics of their spaces with these monsters. I urge the manufacturers to rethink the design!

    • Mam, if I could point out a few things: Most people would consider most anything to cut their utility bills in half. Maybe some folks have a problem with ego over economics. And you think people love to have holes cut in their floors in every room to look at? Now, lets compare the mini split unit appearance with the big return air vents on the wall of every home. You thing that is cool? You cannot hear my indoor unit running even if you stand right next to it. On the other hand, several weeks ago we spent time with a friend who just built a new home. I was awakened three times by that noise when the central system comes on! I been there and I wouldnt go back.

    • There are new models for inverters. If you look at Fujitsu they have the regular unit that you say looks like a refrigerator. Then they have ceiling units, duct vent style units, units you can incorporate into ducts.

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