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. This thread is still going strong. Love it!

    Figured I’ give an update on my experience with ductless mini-splits.

    So last year we built a massive 2 family home in the Northeast (coastal RI to be more specific). I GC’d the project so I was involved in all of the decision making. Each town home spans three floors, has 5 bedrooms, and is over 3,200 sqft with large open living spaces and ample windows and sliding doors (so lots of potential heat loss). The home was a partial modular with the roof/3d floor being constructed on site. 2×6 construction, 8.5′ ceilings, bottom two floors are fiberglass bat insulation, 3d floor is open-cell spray foam insulation.

    We actually had baseboard hot water pre-installed by the modualr factory in the first two floors. The original plan was to have a hybrid baseboard system (natural gas) and then add a central hvac system to cover the third floor and also provide A/C. Or to just do a central air/HVAC system and forgo baseboard all together. Plan B was to just have mini-splits throughout the home that would handle both heat and A/C.

    After fielding a multitude of quotes for the baseboard system, HVAC system, and mini-splits. It turned out that the most economical option (by far) was to go with the mini-splits. A cost savings of about $50K in all. This would also be the most maintenance friendly option as the system is theoretically much simpler…as it’s all electronic. The risks: (a) for homes of this size, in the cold NE, it was questionable whether the minisplits would adequately heat or cool the home, (b) if a noreaster blows through and electricity goes out in the winter, big problems, (c) potential cost increase of electric heat vs. heat via a natural gas system.

    Short story, we went with the ductless minisplits ($50K savingsmade that decision palatable).

    Here’s our layout in each town home we chose to use Fujitsu units throughout:

    1st Floor: (2 BR, one common space) 1 standard condenser, 3 heads
    2nd Floor: (1 BR, common kitchen/living) 1 standard condenser, 2 heads
    3d Floor: (2 BR) 1 hyper-heat condenser, 2 heads

    Total cost for everything: 6 condensers, 14 heads, installation, 1 year warranty parts/labor…$44K (note that the average cost per head unit in RI is roughly $3,500, our average was $3,100…not bad).

    We’re currently going through our first winter and I’ve been staying on-top of the costs. We have full-time tenants in one unit and we are covering utilities as part of the rent (up to $200/mo so they do have incentive to conserve heat). The other unit is rented short term and we pay the bills there as well. The two units are on separate electric services.

    Result: Average cost per winter month for the entire electric bill so far (that’s heat and regular electrical use), is $275. Natural gas (hot water and stoves) is roughly $50. Totaling $325/mo. That’s 3,200 sqft and three floors. Comparatively, my home which is in the same town, is 2,400 sqft and the total cost to heat the house using a natural gas HVAC system is $275 (includes hot water)…but get this…that’s not including my electric bill, which is another $200. Totaling $475/mo. So we are paying about $150 less per month on the bigger building.

    Now, granted, our home was built in 2000 and is 2×4 construction with bat insulation (no sprayfoam). I think that has a lot to do with it as well….but still.

    Note that these numbers are also heavily reliant on the cost of electricity vs. the cost of natural gas/oil. Something to consider. And I’m also not sure what the difference would have been if we stayed with natural gas baseboard heat or a natural gas HVAC system. For all I know it would have been less.

    Needless to say, as it currently stands, I am very happy with the decision to go full mini-split. Time will tell how well these things hold up, etc. but as with all mechanical systems, maintenance is key and I plan on staying on top of that. And to cover the possibility of a potential power outage we are now considering installing natural gas-powered generators, at about $5-$7,500/ea.

    Hopefully this information helps someone wrestling with the same decision!

  2. Say what you want, There are already an estimated 50 million units in use in Asia. And there was an article sent to me from the UK. Many conventional HCAC dealers have bitten the dust because they would not offer the Mini Splits. We all know why. They cant make the big bucks on them. Hard to charge someone several hundreds of dollars for repairs when it only takes minutes to change our a faulty board.

      • Hiya Susan,
        I have the LG brand, model number I’ll have to look it up. They are identical 18,000 btu units heating and cooling, very, very satisfactorily and economically I might add, a bit over 3000 ft sq with tall ceilings. One ceiling fan in the upstairs family area and two downstairs. Length of house is 44 ft. Width is 32 feet. I must point out that is is well insulated. My theory on that was to build concrete and steel. The insulation is on the outside! Foil faced styrofoam. If you dont let the heat in, for example in your attic, you dont have to pay to get it out. When you look at the ratings on insulation, a few inches of styrofoam doesnt score to highly compared with fiberglass, I say baloney. Im going to give you an example; a styrofoam coffee cup with a thickness of less than 1/8″ and 200 degree coffee and you cant feel it! Try that with 1/8″ of fiberglass.
        Ok I’ll be around anything comes to mind let me know.

  3. My husband and I are very disappointed in our Mimi split we put in our bathroom. It does’nt heat the way we thought it would.
    We have to use a space heater too. We love in a brick and concrete house without heat or cooling ducts. The ceilings are 12′
    and we are wondering if this is the problem. Or do you have any other ideas of what we can do to fix this situation?

    • Hiya Connie 🙂 Certainly there is a solution. My ceilings are also 12′ both upstairs and downstairs. Going up those many stairs keeps me in shape for sure.
      I dont know if we can get to the answer on the first attempt because I may need a bit more information.
      First, what size is your bathroom and what size is your Mini Split unit? In my 3600 ftsq house I dont even have a mini split in either bathroom upstairs or downstairs. I have only two units, each 18,000 BTUs. My house is 44′ long and they both point from one end towards the other end.
      Obviously my first suggestion would be to install a small ceiling fan if we determine the unit you have is the right size. Next option would be a Nutone bathroom unit with a light, vent and heater. The heater is so small you wouldnt use much electricity if you only used the heater when you are in the bath/shower.
      People who have Mini Splits often put louvered doors at their bathroom to bring in the heat the Mini Splits are producing outside the bathroom. But I dont even have those. No heating unit of any kind in either bathroom.
      I really want to solve your mystery. There must be a solution. Send me the answers to my questions please and stay in touch!

  4. The article seems very biased against mini-splits and it has a lot of incorrect information. For example “Instead of distributing conditioned air throughout the home, mini-splits distribute refrigerant.” That statement is not only false, it makes no sense. Air is being cooled and circulated in the house–not refrigerant, and the system is really no different than a split-central system with the compressor outside and the blower in the home.

    Also, the author states that air leaks in ducts are not really leaks unless the ductwork is in unheated space, which is a useless statement because ductwork is almost always in unheated space (attics, basements, or crawlspace).

    There is a reason other countries use this system (It is a good system). If it were so bad or central was so much better, nobody would use mini-splits.

  5. No mention of the heating and de-humidifying aspects of these devices, an/or the fact that they away combustion based heating and electric as well, in terms of efficiency. The appeal is it cools, heats, and de-humidifies, at much higher efficiencies than “traditional” systems. The savings on utility bills is somehow overlooked as well, in the cost equation. Hmmm

    • Right on and I can attest to that. First year I had them installed my electric bill went up I think $20 or so dollars YOY for the same period during the summer. That’s vs window u it’s that did their job but were noisy, had to put in and take out, didnt cool every, etc… I’ve had two Summers with mine now and no real complaints. AND….my boiler was acting up a couple weeks ago. It wouldn’t turn on. I had a secondary heat source for my home with the mi I splits until I got the boiler repaired

    • Ours has a dehumidification mode.We dont even use our clothes dryer anymore! Take the clothes from the dryer, hang them on a wooden folding ‘tree’ and walla. Dried for free as the MINI SPLIT is doing its thing.

  6. Better to have a AC unit in the window half the year, or a unit on the wall… have to take it out and store it. Maybe need two people to handle it.

  7. Please think about this. Central A/C 15 year old without problem . 10 years warranties Parts and compressors. Mini split fabricated with garbage. Plastic blowers and control board and electronics parts are models changed from factory each two years and for you is impossible fix. ,
    Bottom line : Mini splits are disposable garbage

    • Oh no. My 12 year warranty, super efficient, hyper quiet, ability to zone room to room and have an added heat source with my minisplit disposable garbage. Laughable.

        • If he has a 12 yr warranty then he likely has a Mitsubishi that was installed by a diamond contractor.
          Standard warranty with Mitsubishi is 10yr if registered , 5yr if not, and 12yr if installed by diamond contractor and registered.

  8. Please think about this. Central A/C 15 year old without problem . 10 years warranties Parts and compressors. Mini split fabricated with garbage. Plastic blowers and control board and electronics parts are models changed from factory each two years and for you is impossible fix. ,
    Bottom line : Mini splits are disposable garbage

  9. Building a 1,292 sq. ft. Home. 2 bedroom(1 is a master bedroom with own bath) 2 bathroom home. Exterior walls will be 2×6’s. 14″ of recyled paper blown in. All interior wall’s will be insulated. Mitsubishi mini split will be installed. Live in south Ga(Thomasvile). Can someone suggest a certified “diamond” contractor to install?

    • Danny, sorry, I cant. They are so simple anyone can install them. That is why I suggest you order online to get the best price. Then call around and ask “What is your hourly rate for a HVAC mechanic?” The normal price just outside Atlanta is $65.00. Takes about two hours. Most units come precharged so you dont have to buy any refrigerant.
      Hope this helps. You have zeroed in on the top of the line btw.Good job! Sam

  10. I have no experience with the single condenser and multiple fan units. Just always felt for less money I could have multiple units and in the event one goes down you are still in business. To facilitate such an occurrence, which has never happened, I have a small floor vent in the upstairs floor and with the stairwell door left open you can feel a constant flow of air with one or the other unit turned off. Never forget one of the basics of thermodynamics’ Heat is attracted to cool.

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