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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526 thoughts on “Four Myths About Ductless Mini-Splits

  1. A comment on the bathroom by one of the posters saying that not too many years ago houses didnt have any heat/cool vents in the bathrooms. I just couldnt resist. Not to long ago you had to go to the outhouse. Would you like some cheese and crackers with that whine. I stated previously, use a louvered door and the exhaust vent in the bathroom will exchange the air nicely. GAWD.
    With my connections, I probably got the first mini splits in the USA. I built my house myself of concrete and steel, super insulated. I downsized both units, upper and lower by one half. They will freeze your arse off in summer and run you out of the house in winter if you want. I have over 3500 square feet and each unit is 18000 BTU. I will be switching both over to my new solar system so they wont cost me anything to operate. Just compare power consumption of the mini splits and conventional systems,. It costs as much to run the central blower motor alone as it does to run my entire mini split. The future is now and all the naysayers need to get on board and profit from the influx rather than trying to defend a defenseless position. Simple as that.

  2. You will most likely never hear a positive comment about mini splits from a ‘professional contractor’. They cant make any money on the because they are so inexpensive. And repairs generally take less than about 15 minutes. There are already over 50 million mini splits in use in Asia. I read an article from the UK about those who refuse to get on the band wagon are going out of business by the droves. They can try to hang on to the old, inefficient technology but if they dont get in on the mini split they will become the dinosaurs. I now have three houses with only mini splits. Two rentals. The only thing I hear from tenants is, “My utility bill is half what it was in my last house.” Just running the motor that drives the fan in the central unit takes more electricity that the entire mini split. Plus the dc current that is used for the mini split can be regulated up and down, meaning if you need more heat/cool the unit speeds up and if it needs less the unit slows down saving energy. Filters take five minutes to clean. No more buying filters. On the ‘bathroom’ comments, if you have a vent in the bathroom, almost all homes do, and you have louver doors then the heat or cool will be pulled into the bathroom by the vent. Basic thermodynamics have been tossed when you are talking to a ‘professional’. Didnt you learn in school that “Heat is attracted to cool?” One of my rooms is 44 feet long. The unit is at one end. In winter the heat from the unit is not blown across the area, it moves by the principle of thermodynamics. And in summer, the same thing happens in reverse. You can out a candle and watch the smoke moving in the direction it needs to go to adequately condition even a large room. I would suggest you buy online, call the local HVAC contractor and ask for the hourly rate, normally here in Georgia its around $60.00 per hour. They can be installed in less than two hours! Having more than one unit means you will never be without heat or cooling unless your power goes out. One fails, the other continues to operate. Normally the wiring capacity for your existing central unit is more than sufficient to operate two mini splits, no problem. No need for extra circuits or a larger box. Actually if you calculated you could have a smaller box and wiring. But dont consider that it is not necessary. The leading brands in a reasonable price range are the LG. The top of the line is probably Mitsubishi as they make almost all the compressors for all the units worldwide and that is why most compressor warranties are the same. There are numerous and sundry other brands, say on the same size units which can cost as little as $600.00 per unit up to $2000.00 per unit for the same output. Again, if you ask a ‘professional’ you are going to wind up with another archaic system which will cost you twice as much to operate.

    • Sam, I am closing on 5 rental properties totaling 11 units here on 12/20… I had been thinking these mini split systems in each unit. They now have baseboard heat and window unit A/C in each one… none of them are over 800 sqft. You have had really good success with these so far? For both heating and cooling? These properties are in an area that could hit or go below freezing at times during the winter.

      • We get into the single digits here in the northern portion of Georgia, about 12 years now an they will still run you out. About 1000 ft sq upper and lower floors with one 1800 BTU units on each level. We have, as I understand it, the third highest rates in the country. I can tell you the greatest advantage in rentals; If the tenant is paying $200.00 utility bills instead of $500.00 utility bills they have a better chance of paying their rent! The mini splits will not compete with each other! The A/C current is changed to D/C current allowing not only the fan speeds but the compressor to slow down if the delta T is close or is met and it will automatically speed up when needed. I dont know of a central system that will do this. Full speed on or its off! I believe if you have a one HP motor on your central blower you are using as much energy just to power the motor as your Mini Split consumes, compressor and all! Say around 700 watts per HP on your blower, now check the consumption on the Mini Split you have or are looking at. For me 18,000 BTUs I am only consuming a bit over 700 watts. The great news is that three $250.00 solar panels can run this size unit for free. Daytime, of course. If you want nighttime usage, you would need batteries for energy storage and an invertor. But hey, if you pay Federal tax and State in some states, they will pay up to $5000.00 via a tax credit. Free electricity to run your Mini Split. THANKS EVERYONE FOR YOUR COMMENTS.

  3. My house was remodeled poorly before I purchased, and my inspector mentioned some issues but didn’t realize how bad it is. We have a horrible stack effect to start, then we have HVAC ducts in the basement that open out into crawl spaces, and some that are not properly connected to vents in crawl spaces that you can’t get to. They are of course a jumble of flex duct which is extremely inefficient for air flow, and the huge plenum and metal ducts which run across the basement are also not insulated and basically radiate enough heat to heat an unfinished basement with massive air leaks to crawl space. Then there’s the ducts in the attic which are loose and leak hot air into the backyard, front yard and everywhere. There is a negative pressure in my home, and when the HVAC in the attic runs, air is getting sucked into the master bedroom with very strong force so that I can’t even keep the door closed without it coming open. The return is just below the vents so that it sets up a constant waste of heat going into the top of the cathedral ceiling, then back through the return into the freezing cold attic, then back into the room again. Neither furnace, despite being high efficiency models, can bring the temperature in the room or floor much above 60 degrees on a cold night in the low 30’s or lower. My gas bill was $400 to keep the house at 58 degrees last winter. So I call the company that installed all these wonderful units and ducts, and guess what, they were rated the #1 HVAC company in my area for 10 years running!!! And they say “oh we would love to help you fix all these, it will only be $100 an hour to design a solution, and then the same to do the work, but we can’t guarantee how much it might cost since there are unexpected issues that might come up during this process.

    My house is probably a worst case scenario, but it illustrates why ducts are such a problem for some homeowners.

    • We recommend contacting your local building inspector to get a list of licensed HVAC companies that they would recommend who perform this type of quality repair service.

  4. i am a professional hvac design, you failed to mention that ductless mini splits are disallowed by Manual J UNLESS the installed equipment capacity closely matches the rooms demand – also no cooling in the baths, walk in closet, laundry room etc.
    show me a customer today that would tolerate a bath room with no conditioned air being delivered to the space.
    ductless equipment is almost useless for a modern residential home unless you choose the type that can be ducted and is properly sized for the space(s). this is why we have duct work, so we can slice up the proper amount of tons per room – ductless units are way too large for a standard bedroom even if the capacity is variable.

    • I’m a customer today who doesn’t mind not having a unit in the bathroom and the space is conditioned because the ‘conditioned’ air flows to the bathroom. My house is 2700 square feet and have zero qualms with none of my three bathrooms having a unit in them. When the door is open I’m super comfy. And if the door is closed, I can’t say I feel that much of a difference. How long does someone need in the bathroom with the door completely closed? Not much here.

      My master bath is on the south west, second floor corner of my home and it’s comfortable. That’s with a mini split on the north west corner of the master and about 30 feet away. Not to mention the years I’ve vacationed in the Caribbean – the mini splits weren’t in the bathroom there either and we were always quite comfortable. Sure, if your in the bathroom for an extended period of time with the door closed, if the systems aren’t installed in ideal locations, or a unit not large enough for the space – there may be an issue. By the way, I have one unit in each of my three bedrooms – again – no issue with sound, too large/small for the space. My installer did an excellent job sizing the units to the space which included the size of the space and the location.

      So………I’m one of those customers……….and never had an issue. For those that think you may need a vent in a bathroom, yes you can duct using a mini split configuration. They did that for my kitchen because while the kitchen is large enough, there wasn’t really a space (with soffits) to install a ductless system. The kitchen has it’s own thermostat and ties into the Mitsubishi unit outside and with the master on the second floor.

      Folks………….I know some people have issues with different things and have differing opinions but ……….. I’m digging my Mitsubishi minisplit for 16 months now and they aren’t in the bathroom.

      • Just how much time does he think people spend in a bathroom? Hours? We live ina very hot and very dry climate in the California Sierra’s and have had a 3-ton system installed in our 1700 sq ft home. No room for a mini in our single bathroom, I was worried but our installer asked me, “Really? You won’t need one in there.” And he was right, we’ve never had an issue. Placing a little desk fan has been more than adequate for the wife during put on the make-up time. The bathroom stays cool just by leaving it’s door open to the hallway or room where there is a system installed. We do have a ceiling exhaust fan with heater in there and it works perfect for a few minutes if it’s cold. Seriously, don’t “sweat it!”

        • Tojo…simple solution to the bathroom or any room for that matter where the door would be closed often. USE A LOUVER DOOR. Very beautiful in most any color but my best is a natural finish. They are made in a couple of configurations. Some dont allow airflow. Just be sure you get the one that does and place it with the high point of each louver inside the room you want private. Works like a charm.

    • Having nicely cooled bathrooms is absolutely one perk of central I LOVE. We happened to have a house where the combination of open spaces and accessible areas for mini splits it was far less money to install a central system. I never want to be without it again. I’d we moved and bought a Cape where it’s more practical to do ductless then that would be the obvious choice. Too many told us Central was our best bet. I’m not against the new systems but each has their ideal use. We are so glad central was ideal for us. No walk in closets here really but I’m sure I’d love that too! We surely have heat loss as all our ducting had to go in an unfinished attic but not much we could do about that. Our electric bills actually went down with central bc we had interior heat waste with AC going to a rarely used second floor. It was cheaper to keep that area cooled with the rest of the house maintaining an equilibrium. And we will eventually be using the second floor more. We do need to put a ductless system in our basement which has no heating or cooling currently. And I’ll be very happy with that as our ideal solution there.

    • You do realize less than a century ago there were many bathrooms without air conditioning or heat and you had to go outside to get to them.

      Which is why I’m fine with a louvered bathroom door and using the bathroom vent to pull cool air from the room when needed. In the case of the master bathroom just up the BTU demand to factor a bathroom and put the bathroom vent on a thermostat.

      House I bought came with a rodent infestation in the roof and the duct work being the “nest” so you know all that insulation is being replaced. Forget the central system and go for a system with lines of refridgerant not air.

      It’s a no brainier when you want to also go solar!

  5. I can get behind some of the arguments made, but you lost me when you talked about cooling your backyard with the refrigerant line. The lines are typically so short that heat loss would be negligible when compared to the loss that would occur when you have poorly sealed ducts losing air into my “unconditioned” attic space. In reality both system have their value. A whole house solution is the most economical way to cool a house from a startup perspective. I worked in the commercial HVAC industry for many years and we still used packaged HVAC system when cost was a concern. They are definitely significantly less expensive than purchasing some of the new variable refrigerant models out there. However all of that being said, a ductless system is a very nice solution for the added space or the one room that just never gets cool. I would not be very excited about a unit in every space of my house but for specific space in the home they work great.

  6. “..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.”

    HA! Really? You call the 100+ degree attic a “conditioned” space? Not in any house I’ve even been in. I worked for many years in the HVAC industry and I’me here to tell you that conventional ducted central air in most residential applications is a hole in the ground where you throw money, and I made a good living off that money. Granted, ductless mini splits are comparatively a new technology that sometimes has a bug here or there, but the main reason conventional ducted companies don’t like them is because they are EASY for a do-it-yourselfer to install, and usually come with easy to follow installation instructions with good tech support. This cuts the big HVAC companies off of the money trough. And, unlike a big whole-house A/C system, you can have 4 or or more well-placed mini-splits heating and cooling the house. And, if one of them goes down, you can still partially heat or cool the house. Ever sit in a house in Texas with no working A/C during the heat of the summer waiting on the repairman to finally show up looking for you to hand him that blank check so he can “fix” your A/C? I’ll never do it again!

    • Hi Steve,
      I’m intrigued by your comment that the ductless systems cut the HVAC guys out.

      I’m looking at the Mitsubishi Hyper Heat systems up here in Boston for apartments and getting prices from HVAC companies between 7K – 11K per system installed.

      Now, I’ve outgrown the do-it-yourself phase (mainly because I’ve realized I’m not very good at ‘it’ -whatever it is). But I will keep searching for installers, if out of trade installers are an option.

      BTW my beef is that the ‘good money’ up here means $2,500 per man a day. And, installation does seem quite straightforward…

  7. No issues. They are very efficient and they cool and heat (they are also heat pumps) better than the whole house system. We live in Colorado and now only run the furnace as a backup on very cold days in the winter. At night the furnace hardly runs because we close the vents to the bedrooms as the heat pump puts out enough heat. the 9000 btu units only use 6 to 10 amps while running.
    Also the furnace works a lot better on the real cold nights because there is no a-coil which reduced the efficiency of the furnaces air flow.
    In the summer we don’t miss the noisy compressor or the noisy air flow from the ductwork.

  8. Due to asthma I can’t tolerate old fashioned swamp coolers, hate noisy heat exchangers, & ducted AC units aren’t recommended. Air ducts get build up of dust, & mold needing periodic cleaning. Having my manufactured home built, I dealt with bias & ignorance against ductlesss mini-splits. Installation was at nearly $2,000 less than an AC installation. The quotes didn’t include duct work since I was forced to allow built-in ducting by the builder. The mini-split is low profile, does both cooling & heating in outdoor temperatures ranging from 30F to 115F. I covered the floor ducts & will turn the dumb thing built inside my livingroom wall, for an old style heat exchanger, into storage. The system works great. While my neighbors’ electric bills run in the $100s during summer months, my average bill is $45 for my 2 bedroom home. It’s quiet, I’ve had it 4 yrs no leaks, smells, gunk, problems, & no maintenace (other than cleaning the filter). I do agree I’d rather not have a line going up the outside wall, but it’s nicely covered and not ugly as what’s shown here. I asked the HVAC installer about two splits. He advised against it because they would compete with each other in my single level home. The guy with the 3 ton and 2 ton units obviously made the wrong choice for his situation. Doesn’t mean mini-splits aren’t adequate. I think there will continue to be a need for AC’s, but mini-splits can be a better choice. Was for me.

  9. Well I have a 3 ton with 3 splits and a 2 ton unit with 3 splits and besides the cost the maintenance is a nightmare! The fan must be hosed off with hot water to get all the funk off! Also 4 of the inside units developed leaks in the aluminum evaporated ! The units would be replaced by Mitsubishi but I would have to pay to extract refig

  10. Well I have a 3 ton with 3 splits and a 2 ton unit with 3 splits and besides the cost the maintenance is a nightmare! The fan must be hosed off with hot water to get all the funk off! Al

    • We live in a Mediterranean climate in California where its bone dry from April through November and our 3-ton system has no severe dust condition. Not any worse than anything else out there. It’s totally waterproof so hose it out, no big deal. We love our system. After 10 months the inside filters look brand new as well. We’ve never needed to clean them. We are loving our Mitsubishi mini-split system!

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