How Do Ductless Air Conditioners Work?

image of a ductless air conditioner

Ductless air conditioners are different from central air conditioners in that they have no air ducts. However, both air conditioning systems work by sucking warm air from a given space and absorbing the excess heat and moisture from that air, and dumping the heat/moisture outside. Because they don’t use ducts, ductless ACs transmit cold air directly into a given room or space. On the other hand, central air conditioners run cold air through a system of air ducts that cool the air in your home. But, many homeowners still ask the question, “How do ductless air conditioners work?”.

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How Do Ductless Air Conditioners Work?

Below is some further information on this subject.

Parts Of A Ductless Air Conditioning Unit

Ductless cooling systems are made up of 3 main parts including:

1. A Blower/Evaporator (Indoor Unit)

fujitsu general ductless hvac systemA blower/evaporator unit is the component in a ductless air conditioner that is situated indoors, in the space or room that the air conditioner serves. The evaporator or blower is thin and measures about 3 inches long. The function of these components is to suck warm air from a room, absorb heat and moisture from the air, and finally divert cold air back into the room. These components transmit cold air into a room while simultaneously expelling the heat and moisture via the ‘conduit’.

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2. A Conduit

A conduit links the indoor section of the air conditioner with the outdoor section. The conduit is a long and thin cable that is made up of a power cable, condensation drain, and refrigerant tubing. This component (conduit) provides electricity to the outdoor and indoor components of the ductless air conditioner. The conduit is also the path via which heat and moisture from inside your home are channeled to the exit point where they are expelled known as the condenser.

3. A condenser (Outdoor Unit)

image of ductless air conditioner compressor

A condenser is basically the outdoor part of a ductless air conditioner. Its work is to collect all the moisture and heat coming from inside your home and expel or dump it outside.

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Single-Zone Mini-Split Vs Multi-Zone Ductless Installations

Is a ductless air conditioner ideal for multi-room setups?

Well, ductless air conditioners are ideal for both single-room/zone and multi-room/zone setups. You can install ductless air conditioners in various setups based on these 2 main models:

Single-Zone Ductless Mini-Split

A mini-split is made up of a single blower/evaporator unit and a condenser. This makes it effective for cooling a single space or room. If you have adequate space to install multiple condensers, you can install several ductless air conditioners that function simultaneously to cool a whole building. This type of system offers customizable temperature regulation in each space. On top of this, if one unit fails, the rest will not be affected.

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Multi-Zone Ductless HVAC

There are 2 types of multi-split ductless air conditioning systems. The first uses a single condenser that’s linked to multiple blower/evaporator units inside a building. In such a setup, each evaporator/blower is coupled with a thermostat. When the air needs to be cooled, all units are switched on concurrently. This setup is much more efficient and cost-effective. It’s perfect for buildings where rooms have varying cooling loads.

If you are looking for a customizable system that offers true zoning, a multi-zone mini-split unit with detached compressor circuits connected to each blower/evaporator unit would be ideal for you. This allows the occupants of each space to control the temperature based on their specific needs.


Do Ductless Cooling Systems Have Enough Cooling Power?

While individual blowers/evaporators may appear small, they’re only meant to cool a single zone/space which is ideal. But, for your indoor unit to adequately meet your cooling needs, you have to match BTU capacity with the size of the space. In general, a larger room or space has a higher BTU rating. It is advisable to establish your cooling load with the help of an HVAC expert. They will consider various factors to determine which setup will serve you well.

A ductless system that is too small will have to work overtime to cool a large room or space. This leads to rapid wear and tear and the need for frequent repairs. In the same breath, a system that is too large will short cycle, which means switching on and off frequently. This leads to discomfort and the inability to remove humidity.

In general;

  • Smaller rooms measuring between 400 and 650 square feet require a ductless air conditioner that produces about 12,000 BTUs per hour.
  • Rooms measuring between 600 and 1000 square feet require a ductless air conditioner that produces about 18,000 BTUs per hour.
  • Rooms measuring between 800 and 13,000 square feet require a ductless air conditioner that produces about 24,000 BTUs per hour.

Contact a professional HVAC contractor to get more information on ductless air conditioning systems. They will be able to help you determine the proper ductless air conditioner size to meet your needs.

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Advantages and Disadvantages of Ductless Air Conditioners

Below, we discuss some of the advantages and disadvantages of ductless air conditioning systems.

Advantages of Ductless Air Conditioners

  • Ductless cooling systems come with in-built zoning. These units allow the occupants of each room or zone to set their own temperature regulation settings.
  • Ductless air conditioners are energy efficient. Ducts in central air conditioners contribute to the wastage of 20 to 30 percent of cooled air, according to With ductless ACs, you will never have to worry about such wastage.
  • Ductless ACs are an ideal and cost-effective cooling solution for homes with no pre-installed ductwork. Many older homes lack the infrastructure and/or space to install new or additional ductwork. On top of this, installing ductwork involves cutting through ceilings, floors, and walls, making it a time-consuming and costly process.
  • Ductless ACs are extremely versatile as they can be mounted on ceilings, walls, and floors depending on your specific needs and preferences.
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Disadvantages of Ductless Air Conditioners

  • While ductless cooling systems have a higher initial cost, they are generally more energy-efficient and cost-effective in the long run. The cost associated with ductwork leaks can greatly increase the cost of operating a central air conditioning system, making it more costly than a similar-sized ductless unit.
  • Unlike central ACs that can be stashed away in a closet, attic, or basement, ductless ACs have to be mounted on an exposed surface, making them hard to hide. But, they are still sleeker and less obtrusive when compared to window AC units.


Ductless ACs are energy-efficient, versatile, and customizable. Furthermore, they remove for air-distribution ductwork, which means that they are easier to maintain and more cost-effective to install when compared to central air conditioners.

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If you need to replace or repair your air conditioning system, we recommend the best system for your home based on your budget. All our work is guaranteed to ensure optimal satisfaction. To book an appointment, contact Miller Oil Company today. We provide free, in-home quotes.
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