What are Ductless Air Conditioners and Are They the Best Cooling Option

Updated: Mar. 08, 2024

Sleek, efficient and relatively easy to install, a ductless air conditioner or mini-split can quickly cool (or heat) your rooms.

Our editors and experts handpick every product we feature. We may earn a commission from your purchases.

A ductless air conditioner, also called a mini-split system, can be a quick and easy way to cool a room when it’s hot and warm it when it’s cold. Let’s see if a ductless air conditioner is right for you.

What is a Ductless Air Conditioner?

A ductless air conditioner cools down (or heats up) your living spaces without ductwork. The mounted units don’t require a large footprint on the floor, like a portable air conditioner, or take up a window like a window unit. They are also known as mini-splits because they are significantly smaller than traditional central air conditioning systems, which are called split systems.

How Do Ductless Air Conditioners Work?

Most mini-split systems are heat pumps that can cool and heat a room, garage or small apartment. A heat pump transfers hot air from one place to another.

A ductless air conditioner, just like its larger traditional counterpart, has two main components:

The power cable, refrigerant tubing, suction tube and condensation drain are housed in a conduit that links the outdoor and indoor units. The conduit snakes through a hole in the wall.

Types of Ductless Air Conditioner Systems

Ductless air conditioner systems, or mini-splits, come in three types, each catering to different space needs. Wall-mounted systems, the most common type, deliver cooled air from a high position and are best suited for individual rooms. Ceiling recessed units, or cassettes, are ideal for large rooms or open floor plans, pushing air in four directions from a hidden spot above the ceiling. Floor-mounted units, installed near the floor level on a wall, direct airflow toward the ceiling and offer convenient maintenance and operation.

Wall Mounted

The most common mini-split air conditioning system is mounted to the wall. The motorized vanes at the bottom of the unit push the airflow out and down. This type of system is best for cooling a single room.

Ceiling Recessed

Also called a cassette, a mini-split recessed into the ceiling is ideal for a large room or open floor plans. It sends the air in four directions at once. This type of unit requires 10 inches of clearance above the ceiling for the housing to fit out of sight.

Floor Mounted

A floor-mounted mini-split is installed at the bottom of the wall, near the floor. It doesn’t rest on the floor, but is anchored to the wall a few inches above. It directs airflow toward the ceiling. Its convenient floor-level position makes it easier to keep clean, access for maintenance and operate with or without a remote.

Factors to Consider When Choosing a Ductless Air Conditioner

When shopping for a ductless air conditioning system, consider the size of the room, where the airflow is needed and the unit’s energy efficiency.

Correct Capacity

The British thermal unit (Btu) rating is the unit’s capacity.

  • 9,000 Btu for areas up to 450 square feet
  • 12,000 Btu for areas 400 to 650 square feet
  • 18,000 Btu for areas 600 to 1,000 square feet
  • 24,000 Btu for areas 800 to 1,300 square feet
  • 30,000 Btu for areas 1,500 to 2,000 square feet
  • 36,000 Btu for areas 2,000+ square feet


There are two main energy-efficiency metrics to know. The bigger the number, the higher the energy efficiency.

  • The U.S. Department of Energy requires a Seasonal Energy Efficiency Ratio (SEER) of 15 or more for mini-splits. Energy Star systems will have a SEER of 20 and 25.
  • A Heating Seasonal Performance Factor (HSPF)¬†of 8 to 10 is ideal. Energy Star will award a label if the HSPF is 8.2 or higher.

Advantages of Ductless Air Conditioners

A few of the factors that make a mini-split a wise decision include:

  • Individual room temperature control. You can use your mini-split unit for zoning or cooling and heating individual rooms. If you have someone who prefers to sleep in the cold while the home is at a steady 78 F from the main air conditioner, a ductless air conditioner can keep their room chilly without running up the electric bill for the entire home.
  • Efficiency. The mini-split runs at 30 percent less power than traditional window or through-the-wall air conditioners.
  • Small size. The indoor units tend to be about seven inches deep with flat fronts and aren’t as bulky as less efficient window or swamp cooler air systems. The size of your mini-split depends on the size of the space you need to cool.
  • DIY friendly. The hook-up between the outdoor and indoor unit typically requires a three-inch hole for the conduit. Many mini-split system manufacturers offer varying lengths of connecting conduit so the outdoor unit can be conveniently located up to 50 feet (on average) from the indoor unit. The refrigerant line must be cut and then charged. If you aren’t comfortable with that, you can do the install yourself and hire a professional to complete the refrigerant line setup.
  • Installation options. You can hang an indoor unit flush to a wall, mount it to a drop ceiling or suspend it from a ceiling.
  • Remote control. The system can be conveniently turned on and off without flipping the switch if it’s mounted on the ceiling or other difficult-to-reach location.
  • Security. The opening for the mini-split system is small compared to a through-the-wall or window unit that can be removed, creating a security concern.

Disadvantages of Ductless Air Conditioners

Although a mini-split system is efficient, it does have some disadvantages.

  • Cost. A ductless air conditioning system will cost between $700 and $1,000 for 9,000 Btu and $1,500 to $2,000 for 12,000 Btu.
  • Proper placement and installation. The average DIYer can install the mini-split. However, there are a few important things to consider.

    Make sure to measure where the indoor unit will be placed in relation to the outdoor unit. The indoor unit needs to be mounted securely and the conduit must safely connect to the outdoor unit. Consider the direction of the airflow from the unit. If the unit blows air down, a corner placement may not cool or heat the room well. Place the unit where the flow of air will be unobstructed and reach all the zones you want. Consider if the air flow from the unit needs to be aimed down, up or in many directions, like in a room with an open floor plan.

    Installation can be labor intensive and take a good part of a day to mount the indoor and outdoor unit. The units will need to be lifted and held in place as they are secured to the wall. While mini-splits are compact, they can weigh around 60 pounds. If not properly installed, the mini-split can pull away from the wall, not work well or leak refrigerant.

  • Aesthetic. The units are sleek, but the boxy rectangles do bulge out from the wall or ceiling.

Why Choose a Ductless Air Conditioner?

Comfort and savings are the main reasons to buy a ductless air conditioner. It can improve airflow in areas where a system with ducts isn’t an option, and it can decrease energy usage in areas where running a central HVAC system year-round is wasteful.

Because of this, a mini-split is ideal for garages, bonus rooms and sunrooms. If your favorite room is blazing hot in the dog days of summer and freezing cold in winter, a ductless air conditioner can keep the temperature at a steady, comfortable level.

Mini-splits are also a good option for cooling or heating only rooms that are being used, saving you money. And in older homes with a boiler heating system, a mini-split’s cooling and heating can keep interior temperatures comfortable all year.