Busting Myths on Ductless Mini-Splits: Part II

Revisit the Four Myths that I Proposed were “Busted” Three Years Ago

Revisiting the July, 2013 post, “Busting Four Myths About Ductless Mini-Splits”

When I wrote the “Busting Mini-Split Myths” article in 2013, I did not think it would become the most viewed article on our new website but it has over 365,000 page views and counting! I guess I would attribute the popularity of this topic to how new these systems are and how different they are from conventional, ducted, central HVAC systems, which are found in over 80% of the homes in the U.S. However, in addition to the volume of traffic the number and quality of the posted comments and questions has also been remarkable (over 270 to date).

Although we started out trying to provide a balanced view on this new technology for consideration, I found that I also learned some things as the user feedback continued to come in. This led our team to do some additional consumer research into the U.S. Mini-Split phenomena and this research will now appear in some new articles written by Eric Strausbaugh.  Without going into the details of the study, I thought I would use some of the findings from the study, along with the knowledge contained in the many posts on this site, to revisit the four myths that I proposed were “busted” three years ago.

busted-myth-or-magic

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

Status: Still Busted. While mini-splits are growing a little faster than the sales of central systems on a unit basis, the dollars spent on these systems and the number of BTUs of capacity getting installed is still a fraction of that spent on traditional central systems. The reason for this is that the majority of the installed base of homes (over 80%) have pre-existing ductwork. It is simply less expensive to replace a ducted system with another ducted. The air quality and humidity control benefits from central AC are also contributing factors to the staying power of central systems.

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

Status: Still Busted. Our recent research suggests that only a small percentage of people are trying to use mini-splits as a whole-home heating and air conditioning solution; these are mostly in very small homes with no existing ductwork available. What appears to be more popular recently is the “hybrid” approach of keeping the central system for the bulk of the whole home comfort, air flow, air quality and humidity control but also use one or more mini-splits to address areas where consumers want more direct control or where the central, ducted system is not keeping up. Our research articles will go into more detail about this and theories about why this is happening.

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

Status: Mixed. Based on our research and the comments on the original article, I would say that there are definitely instances where poor or failing ductwork has led to major problems with central systems. No one can argue that the most efficient way to run an air conditioner is to turn it off. If you intend to turn off an entire mini-split zone for long periods, these systems will use less energy than a home that does not have zones that can be shut off. I am giving this a “mixed” rating due to the comments about people also using zones in ducted systems, in addition to comments about energy losses in the long line sets for mini-splits.

However, it has been shown that mini-split installation can also have serious “leaks” as long line sets on the outside of the house can pick up heat in the summer and lose heat in the winter. The result can be significantly higher energy costs than would be expected based upon the rated efficiency of the system.

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

Status: Mixed. Based on user feedback, I would have to say that for certain situations mini-splits can do a great job and at reasonable costs. However, it would also appear that for whole-home solutions in larger, U.S.-style homes, the hybrid approach of using a base central HVAC system along with some mini-splits for certain areas provides the best overall approach to both comfort and energy efficiency. Combining this hybrid approach with an automated duct zoning system for the main central HVAC would also improve the performance of the overall hybrid approach.

The Bottom Line on Ductless Mini-Splits

If you want to learn more about this topic, check out our first article on the survey of over 350 people who have purchased mini-splits in the past 1-5 years. In the meantime, we would encourage anyone in the market to get a few different quotes for each of the various system types that are available today and consider mixing and matching them to meet your unique needs. It is important to get multiple quotes not only to get the best price, but also to find the right contractor who can recommend the best equipment solutions for your situation, then install and service them well.

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62 thoughts on “Busting Myths on Ductless Mini-Splits: Part II

  1. Why can’t I get a straight answer re which system removes more humidity? I do not have vents and really wanted a mini-split sytem. After parading 5 contractors thru my home with this in mind, the last one came in a told me I was wasting my time with mini-split as it does not remove humidity? I received 2 other estimates from the mini-split folks. I am a single senior and need something for health reasons that removes humidity. HELP!

    • Regardless of what you hear many contractors are not familiar with mini splits. The almost al have superior control systems that should allow humidity removal equal to the best of the traditional split AVPC units.

    • Most AC equipment is rated in BTU’s of heat removal and does not provide pints of water removal. We suggest having AC equipment installed for comfort cooling and using dehumidifiers for additional humidity removal to get to the humidity level desired.

    • Most/all air conditioning systems will remove humidity when they are sized properly for your space. There are other articles and posts on this site that go into the details on this but basically, if your system has too much capacity for the space (load) then it will not run long enough to circulate the air and removed (via the little plastic condensation tube that runs from your unit to a drain). If your system is sized too small then you will get good humidity control but it will not keep up with the temperature and you might not reach the set point temp on the hottest days in your area. The problem with humidity control with mini-splits is mostly about sizing. To cool a whole home you might need 2-3 mini-splits with multiple indoor cooling cassettes for each. If you don’t have enough capacity (or too much capacity) for the cooled space you could have problems like this. Variable speed or two step systems help with this. Whole home central units have the benefit of circulating air through the whole space but if you want to zone off and only cool certain spaces you can do this easily with mini-splits but you need to tell your contractor exactly what you are trying to do and with exactly which space so they can size the system properly. Hope this helps.

  2. Frank
    I’d really appreciate your insight
    I have 2300 sf two story plus basement in Norteast PA. House is 30 yrs old, very well insulated for electric heat.(Electric heat was changed to natural gas/hot water baseboard due to high operating cost.) House has never had A/C. I use window units. I want to add cooling only A/C to the whole house because putting in window units is starting to be a challenge and also It would be hard to sell the house without permanently installed system. Running ductwork is the problem. For the 4 upstairs bedrooms I could install a central air handler in the attic but there would be no easy way to change filters on a regular basis ( only a small access door to attic in one closet). I’m thinking of installing one mini cassette in each of the 4 bedrooms supplied from one outside condensing unit but have the following concerns:
    How well will a system work if only one room is calling for cooling? The condensing unit will be , at best, operating at one quarter capacity. Can these inverter units be turned down that far? I understand that efficiency will be impacted but will the system even operate that way. It’s hard for a homeowner to get that information online from the manufacturer.
    My other concern is cleaning mini cassettes. I’ve seen several posts about mold and tedious cleaning. I was hoping that one of the benefits of a self contained mini cassette was that I could change/clean the filters and air flow path regularly since one of my frequent visitors has allergies. Generally what is your experience with maintenance of these units. I plan to call several contractors but they may not have a lot of experience with these. I plan to talk to them about the downstairs areas because other options may be available there.
    Frank THANK YOU for maintaining this site. I’ve been researching this for several months & this, by far, is the best source that I have found.
    Thanks also to all the posters who have taken the time to share their stories

    • Hi Robert,
      I installed a conventional system in my house that had hot water heat and no ductwork and it worked out great. However, if you want to consider mini-splits you should get quotes for both system types and find contractors who will work with you on your application. In either case, you will need to have a contractor who listens to your concerns and tries to solve your problems which may be unique relative to a lot of other applications they see in your area. Variable speed or mechanical capacity turndown should not be a problem with either system as long as you ask about it and have the do the sizing right (i.e. get the right capacity for your space and usage). On maintenance, cleaning the air filter is important with either system so you are right to make sure you can get to them to do that but maybe the contractors can help you with that. Removing the condensate (condensed moisture) from the evaporator is another issue you need to deal with in either case but with mini-splits it can be more difficult. As for air-flow between rooms with mini-splits, this can be a problem too but you can overcome it by keeping the room doors open and having ceiling fans or a whole house fan somewhere to keep the air moving. You might also try replacing just one window unit with one mini-split to see how it goes before jumping into a whole home project. These are just a few thoughts for you to consider. Thanks for using our site. Good luck with your HVAC project!

  3. What would some practical options be for a 250 unit , 15 story apartment building, constructed in the early 1950’s, that currently has window units? Cost for residents, of course, is a major concern, but the windows are older, very inefficient and scheduled to be replaced in the next 2-3 years. I am wondering if alternative cooling methods might be practical for the apartments (average 800 sf), and if that would extend the life of the new windows while being more aesthetically appealing (exterior as well as interior). Any ideas are welcome!

    • We recommend having a commercial contractor visit your location to provide an in-depth analysis on what options would be suit your need. They should perform a manual J calculation to determine the buildings cooling requirements and then provide a few equipment’s options and budgetary cost. It would also be good to have at least 2 companies perform this evaluation as one company may be more experienced in retrofit situations.

  4. I have an 800 square foot house that currently has a Carrier furnace and condenser. The furnace went out this week. The duct-work, all under the house which is built on rock, is collapsed in places and has a few rat chews, as well. The house is just a one-bedroom with a large LR-kitchen and little bathroom. There are two ducts are in the LR, one in the bath room and one in the bedroom. The house has little insulation, is in the mountains (national forest) and gets cold though it rarely snows here. During the summer, it can get hot, but not miserable for long, since it’s coastal CA. I have many options and am trying to decide if I should even consider a mini-split. In my situation, do you see it as a good option? Thank you!

    • We would suggest that you contact a qualified contractor nearest to your area for a quotation, but to also get different opinions on the installation project, equipment types, sizing, and efficiency levels. The ACCA – which is a national contractor organization have a contractor locator tool which may also help you find a qualified contractor in your area. Here’s the link: http://www.acca.org/locator

  5. We had a mini-split installed in a little-used space in our (otherwise central air and furnace climate controlled) home in 2004. It did the job fairly nicely, however, it was prone to maintenance problems pretty much from the start. We called on our service contract a lot. Now here we are, it’s 2017. The service contract organization, who installed the mini-split, is dragging their feet about repairs. Are newer units any more robust?

  6. Hello,

    What other options exist for a home in NW PA that is built on a “slab on grade”? I am currently doing a total remodel, so I am down to bare studs. Are there other options for running ductwork without a basement or attic area?

    • Hi Tim – Mini-splits might work as would window units or through the wall (PTAC) systems. Another option might be high velocity ducted systems that use really narrow diameter ducts that are easier to fit into tight areas. You can do a search on the above terms to get some ideas going. hope this helps.

  7. I first learned about mini – splits in Iraq. That was the main A/C and heat we used. 120 to 130 degrees outside and the mini kept us cool. Even it tents. Central air in a tent or hootch wasn’t as good. They are used all over Europe and the Mid – East. I built a house two years ago and went with a mini. Low electric bills and comfortable. I did HVAC on military wheeled vehicles when I was there and in Afghanistan.

  8. Frank,

    You may have misunderstood what I wrote, but to clarify, there is currently no A/C system in the house, and no existing duct work, so we are starting with a clean slate.
    There is a small wood stove in the living area, but it doesn’t put out enough to heat up the bedrooms, and even if it did, there is no circulation between the living area and the bedrooms.

    Thank you for your reply!

    • Sorry. I thought you already had some ductwork. Most of my comments still apply but it depends on how much you want to spend and how much time you are going to spend there and in what season. In any case, keep the wood stove for a while until you get used to your new system. Heat pumps can be pretty energy inefficient at low temperatures.

      I would also get quotes for both ductless and ducted and maybe some combinations of each for different spaces. Sometimes it takes a while to find a contractor who is on the same page with what you want to do.

  9. We have purchased a small single story home in the hills of WV, and we planning to install a ductless system for our heating and cooling needs.
    Only half the house has the option of having traditional ducts installed, and that is the main reason for selecting the ductless system.
    The house is about 1200 sqf total, with one bedroom on the 2nd floor that has big windows on all four walls and a South facing sun room (converted from a porch and is insulated).
    With temperatures in WV ranging from close to 0 degrees in winter to the high 80’s in the summer, and almost endless rainy days in spring and fall, what are the pitfalls and advantages of the ductless systems applies to our situation?
    Will a heat pump be of any use during the cold winter months?
    Does the systems remove enough of the humidity to keep the inside comfortable during the rainy months?

    I have many more questions, but those are more geared towards a local installer.

    Thank you!

    • There are many different opinions about the questions you are raising and most have been discussed and debated on this site in the various posts and comments. I would encourage you to read a few of the opinions and make up your own mind about the risks and tradeoffs. Here are mine.
      I think you should look into retaining the ducted system in the space it is servicing. Look into a gas furnace to go along with either an AC only or an AC heat pump. This would give you the benefits of whole home air flow and filtration along with the utility of the gas furnace for the coldest days and nights when the heat pump has to go on auxiliary resistance heat which is not very efficient. In addition, I would look into either ductless options or a separate new ducted system for the space that has no ducts. With ductless, you get the benefits of zoning and room by room control but the airflow is limited to the areas around the indoor units. Using the ducted central system and some other fans, etc could provide proper mixing of air throughout your home. The humidity issue can be addressed by either ducted or ductless systems but it has to be sized right to achieve the right run time to insure good dehumidification. If you get a variable capacity system in either the ducted or ductless models (or both) it might be a little easier to keep the humidity levels low even in the shoulder seasons of spring and fall.
      The pro mini-split visitors to this site will advise that you should remove the old ductwork and go to all mini-splits due to the cleanliness of the ducts and energy losses associated with air leaks, etc. These are valid concerns and if the ductwork in your home is in bad shape or really dirty you might want to consider abandoning it and going with ductless. However, if it is clean and in good shape though, the benefits of whole/partial home air flow and filtration might be worth considering. We always encourage our visitors to get several quotes from different contractors to make sure they are on the same page with what you are trying to achieve. Good luck with you HVAC project and thanks for visiting our site!

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