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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515 thoughts on “Four Myths About Ductless Mini-Splits

  1. Big problem with mini splits is cleaning! Few companies know the correct way to clean inside units! In my area, high humidity, fungus and/or mold clogs up evaporator and air flow is greatly diminished! There is a product to spray on evaporators which kill ,clean, and put a preventative film to keep mold fungus at bay for awhile! Other problem is inside air fan wheel gets covered with mold/fungus and has to be removed to clean which is difficult but can be done! There is a power clean option but requires sprayer with mold/fungus cleaner mix with hot water and water catch system which will clean evaporators and fan ! So don’t put your inside unit more than 8 feet high as higher makes it hard to get to unit! You can’t beat the comfort and quiet operation and efficiency of units, plus with 3,000 square feet and outside temps of 103 plus in summer my electric bill rarely gets over $250 a month!

  2. In our town, the local library had their chiller system go offline and had to close the library!! I think repairs on that dinosaur over the years were more expensive the the cost of installing the system. Well ,you know me. I step right up and say MINI SPLITS! The Library Board had a grant for about $150,000. for a new system. My one best estimate would have been about $225.000. But Im retired and was just trying to save our local government some money.
    “They” call in ‘the experts, HVAC folks, engineers, and they recommend the same dinosaur! Deficient, troublesome, and at a cost of over ONE MILLION DOLLARS! They all said you couldnt use mini splits in that building!
    Wait, it gets worse; The Commissioners vote to do the deal. The library is closed all this time because of no HVAC. If I may, I would like to point out with mini splits you are never really ‘down’. One unit goes out you are still in business as the others continue to operate. If it has to be replaced, TWO HOURS, TOPS!
    The County doesnt have available funds so the hock the new administration building for a million dollars! Crazy right?
    This is in response by the author’s recent ‘advice’ to contact a ‘pro’. That presents a number of problems. The Pro doesnt know anything about this new system and this is not the worst of it. They cannot make the big bucks on a Mini Split they are used to making on the central systems! So, what do you think they are going to recommended? If you have plenty of money to throw away and you dont care about cutting your utility bill in half, fine with me. Otherwise look at the tonnage plate on the system you are replacing. That tells you what the amount of cooling you will need with Mini Splits…well not really, your existing unit is probably oversized by around 25%. Anyhow it gives you a guide.
    Call a couple of local HVAC companies and ask, “What is your hourly rate for service calls?” Probably around $60.00. Go online and order a few Mini Splits and place them around the inside of the house. Its really hard to get it wrong when you have a unit or two that will freeze your arse off in summer and run you out of the house in winter, you know, like a sauna. So there are my thoughts for the day and you will have saved probably around $3000.00 plus you will not longer have your indoor air blowing through long vent systems which are full of garbage, pollen, dirt, bacteria and mold, fungus…well you get the picture.

  3. 3 story narrow townhouse. 2 tiny rooms on top floor plus a small bathroom and a medium bedroom.
    Basement level RecRoom entirely underground. Oil furnace & oil h20 heater in one room. Oil Tank in another room. 100 Amp … cannot be upgraded to 200 Amp or Propane due to building/ complex location. Main floor open space plus tiny kitchen no door. Ducted force air heat. Do I get Electric Furnace with add-on coil to air handler and rip out oil tank but use duct system already in place?

    • We would recommend contacting an authorized contractor that could evaluate your situation and offer quotes on different equipment types, sizes, and efficiency options. It would be best to find 2-3 different HVAC contractors to get opinions and competitive pricing.

      The ACCA has a contractor locator tool which may help in finding a qualified contractor in your area. You can find it at http://www.acca.org/locator

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