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When Should You Install a Ductless Air Conditioner

Comfort Cost Savings

What’s the difference?

Air conditioners provide cool air through two forms of delivery: ducted or ductless systems. The majority of homes in the U.S. are built with air ducts made from sheet metal that run from the main air conditioning unit to each room in the house. The ducts are hidden in walls and air is delivered to each room through vents. In ductless systems, the refrigerant from the outdoor condensing unit is sent directly to an air handler located on the wall or ceiling of a particular room.

While a ductless system can have several benefits, many homeowners with existing ductwork will be better off from a financial and comfort perspective by using a ducted system. The benefits and concerns of a ductless system are:

Benefits of Ductless

  • Easy for a contractor to install (no ductwork)
  • Some flexibility in location of air handler
  • Ability to cool the home by specific zones
  • Quiet when operating

Concerns with Ductless

  • Reduced overall indoor air circulation and increased humidity can lead to comfort and air quality problems
  • Appearance of the air handler on a wall or ceiling in each room
  • Higher cost of ownership for a whole-home solution if your home already has central AC
  • External refrigerant lines which could cause energy losses and aesthetic concerns
  • Serviceability and ease of repairs could be a problem as the unit gets older

While we don’t recommend a ductless system for most homes, there are several situations where a ductless system should be considered over a traditional ducted one. These include:

  • Room additions or adding cooling to a garage or work space
  • Cooling smaller, older homes without existing ductwork
  • When space is at a premium and ducts won’t fit
  • When replacing a less efficient window/room air conditioner

The bottom line

Your comfort, humidity and long-term reliability should all be factors in making a smart decision. As with any important HVAC question, it makes sense to talk with a professional. Contact a reputable licensed contractor who can explain the many options and variables when it comes to selecting the best solutions for your needs.

If you’re considering a ductless system, what are some of the reasons it appeals to you?

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6 thoughts on “When Should You Install a Ductless Air Conditioner

  1. Are there any ductless units that remove the humidity? It would seem to be a simple process and require only a small drain tube to go through the wall along with the pipeset and power.

    • Ned,

      Most common units do have this feature that allows the condensate to drain externally, like you suggested. The real drawback with Mini-splits is air circulation. Ductless systems don’t seem to circulate the air throughout the house as a more common ducted system would. This limited circulation leads to a lower “comfort” level when comparing the ability to control whole house humidity to a common ducted system.

  2. I will be building a large house in Houston TX., On occasion I will be home alone and will not need to cool the entire house.
    My question is have you heard of a residential application of both Central AC and Heat combined with a ductless system.

  3. I will be building a large house in Houston TX., On occasion I will be home alone and will not need to cool the entire house.
    My question is have you heard of a residential application of both Central AC and Heat combined with a ductless system. .

  4. The short answer is yes. Some people have used ductless mini-splits in conjunction with a central AC system. Typically, the ductless mini –splits are used in the more remote areas or rooms that are used less frequently or might be located far away from the central AC system – e.g. an attic space or “bonus” room that is frequently zoned off from the rest of the house or used only occasionally.

    Depending on the size or the layout of the house you are planning, you should also consider two central systems – usually one for the upstairs and another one for the downstairs. This way, you can adjust the temperature up or down in those areas independently and reduce your overall energy consumption. For the areas where people will be sleeping at night I would also consider a central system with some sort of capacity modulation – either one with two steps of capacity or continuous capacity control along with a variable speed or stepped indoor air handler. This will be especially important in Houston because of the comfort and health problems associated with humidity control are almost as important as the temperature control. If you go with a capacity control system, usually 16 SEER or greater, the system will be able to adjust to the load on humid nights when you need the system to run at low capacity for a pretty long time to make sure the humidity is removed and the air remains fresh and filtered. The same system can still run at the full load capacity during the day when the demand for cooling is most critical. The other benefit of these systems is that they are really quiet when they run at the low capacity mode. I have a two step system and I can barely hear it when it runs at night on low load.

    I really appreciate your posting this question. I know investing in a new, custom built home involves a lot of decisions and unfortunately the HVAC decisions are sometimes overlooked. In a hot, humid area like Houston it would be good to consider the comfort and energy cost factors as well as the many other decisions you will be making. Good luck with your new home!

  5. I have concerns with installing one in a small condo in Myrtle Beach right at beach front with the humidity??
    Not sure if ths will work well being in this constant ocean air climate.

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