If you’re looking to eke out an extra living space in an attic, garage or basement this summer, don’t think your only choices are to swelter or install a clunky window unit. A ductless cooling and heating system, also commonly known as a mini-split system, is a popular alternative to the traditional ducted HVAC system outside the U.S., and it’s quickly gaining popularity stateside. The ductless HVAC is perfect for small additions or entire older homes without the space to install traditional ductwork.

What Is a Ductless HVAC?

A ductless or mini-split HVAC system uses an outside unit called a condenser and an inside unit called an evaporator to heat and cool a home — you guessed it — without ductwork. These units are connected by minimal refrigerant tubing and electrical wiring. Many professionals also call the evaporator an air handler or simply the indoor unit.

The term “mini” refers to the size of the outdoor unit, since it’s substantially smaller than a typical split system’s outdoor unit. But the inside unit is hardly obtrusive. Inside units are typically about two and a half feet long, a foot tall and 9 inches deep, and are installed high up on a wall above eyesight.

How Do Ductless HVAC Systems Work?

The casual observer might equate a ductless mini-split system to a modern window AC, but in truth, a ductless HVAC operates in much the same way as traditional central heating and cooling. The main difference is that instead of an evaporator unit being located in an attic or basement, the small, sleek, wall-mounted unit serves as the evaporator.

The indoor unit delivers heated or cooled air directly into the living space — no ductwork needed. In the summer, it pulls warm air from the room and passes it over evaporator coils filled with refrigerant. The refrigerant absorbs the heat from the air and directs it to the outdoor unit.

To heat the house, the ductless HVAC simply reverses this process, absorbing heat from air outside the house and passing it to the indoor air handler. It’s all about heat transfer, combined with air circulation.

How are Ductless HVAC Systems Installed?

Ductless HVAC systems are much simpler to install than traditional central HVAC, but they still require a professional. The HVAC professional drills a small hole through the house to connect the outdoor unit with the indoor air handler. This hole is only about 2-3 inches in diameter and holds the refrigerant line, condensation drain and power cable. If you have multiple indoor units, each of them will need to be connected to the outdoor unit, but this can still be accomplished with a single hole and tubing, similar to plumbing work.

Can a Mini-Split System Heat and Cool More Than One Room?

Ductless HVAC can absolutely serve more than one room, depending on the size and layout of the space. As long as there is open airflow between the rooms, multiple rooms can make up a ‘zone.’

Just as you might have an upstairs and downstairs unit for central heating and air, you can have multiple units in a ductless HVAC system that create multiple zones. Airflow and the size of the space are the main factors for determining if you might need multiple units, but comfort is another big factor. With multiple units, you can set an entirely different temperature for your kitchen and living space than your bedroom.

How Big Does My Mini-Split Need to Be?

Single ductless units come in various sizes, heating or cooling anywhere from 150 to 1,500 square feet. Units are sized by their capacity to process BTUs (British Thermal Units), or the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

The size of the zone you want to air condition is the most important factor determining the size of your unit, but ceiling height, insulation and your location’s climate also come into play. Since ductless HVAC systems require professional installation, your HVAC associate can advise you on the best size for your space.

Are Mini-Split HVAC Systems as Effective as Central Air?

Throughout much of Europe, Australia and southeast Asia, ductless HVAC units are the heating and cooling system of choice. In single or multi-zones, for heating or cooling, they offer comfortable, customizable and efficient solutions.

Their ductless nature also makes them much more energy efficient. In a central HVAC system, up to 25 percent of your energy use is lost in the actual ductwork; you don’t just heat or cool your room, you heat or cool the air in the ducts — located in the least conditioned parts of the house.

How Much Do Ductless Systems Cost to Install?

Just as with central heating and air, the cost for ductless HVAC systems depends on multiple factors. You pay for outdoor and indoor units separately, and there’s a range of models and sizes on both. As with most appliances, the more efficient the unit, the more it usually costs. If you need multiple indoor units, that will raise the price as well.

Speaking in broad averages, though, a ductless system ranges between $2,500 and $5,000. Compare that to the average central HVAC system, which usually costs about $6,000-$8,000 if you already have good pre-existing ductwork or $10,000-$14,000 if you need to open up walls and ceilings to install ductwork.  

How Long Will a Ductless HVAC System Last?

The lifespan of a mini-slit system is comparable to a central HVAC system, and in many cases longer. Central heating and air usually lasts about 15 years. Ductless HVAC systems last 20-30 years. Of course, the lifespan of a ductless HVAC system depends on multiple factors including how much you use it, whether you keep up with maintenance, and the quality of the units you purchase.

Pros and Cons of a Mini-Split System

To sum up, there are 5 main advantages of a mini-split HVAC system, and just a few situations where it is not ideal.

Ductless HVAC Pros:

  1. Cheaper to Install and Maintain: Mini-splits cost less to install and use less energy because they do not require ducts.
  2. More Energy Efficient: Mini-split systems range from about 15-38 on the Seasonal Energy Efficiency Rating (SEER), which is 25-50% less than the average central HVAC system.
  3. Lasts Longer: A well-maintained ductless HVAC lasts 5 to 15 years longer than central HVAC.
  4. Increased Comfort: With multiple indoor units, you have zone control, meaning each room can be set at a different temperature.
  5. Reduced Noise: Mini-split systems are the quietest HVAC units on the market. There’s no noise of air moving through the vents and no noisy clanging on and off like window units.

Ductless HVAC Cons:

  1. Aesthetics: Most people’s major objection to a mini-split system is that they believe the indoor unit is an eye-sore. Although modern units are sleek and small, they are still quite visible in a room. 
  2. Upfront Costs: Although ductless HVAC systems are cheaper to install for un-air-conditioned spaces, the cost to replace your central heating and air system would be significant.

The best situations for installing a ductless HVAC system or a single unit in your house include new additions, older homes with no current central heating and air, rooms with heating or cooling problems or if there are significant unused portions of the house.

East Tennessee Ductless HVAC Installation and Maintenance

City Heating and Air Conditioning can answer all your questions about mini-split HVAC systems. Our experienced HVAC technicians know the best situations for ductless units and can help you choose the right system for your needs and install it with ease. We will do everything necessary to make sure your HVAC system runs as efficiently as possible so that you can stay comfortable in your newly converted spaces as the weather changes. To schedule a ductless HVAC consultation and installation with a trusted Knoxville HVAC company, give City Heating and Air Conditioning a call at 865-938-1005 or fill out our online form.