What Is a Mini Split—and Why It's Perfect for Cooling Your Home This Summer

While central air has become the standard of maintaining a comfortable temperature in modern homes, there are a number of options for heating and cooling your space, depending on the specifics of when and how your house was built. Certain homes, for example, were not built with adequate ducts, which are used by conventional central air conditioning systems. In this case, a mini split could provide an ideal heating/cooling solution. But what is a mini split, and why do some homeowners prefer it over window AC units and central systems? 

We turned to HVAC experts to get all the details (and many advantages) of mini splits.

What Is a Mini Split? The 101 on This Modern Unit

As HVAC expert Al Fagundes explains, "a mini split is a type of heating and cooling system that’s designed to control the temperature in individual rooms or areas of a home without the ductwork of a traditional central HVAC system."

The mini split has two main parts: an outdoor unit that handles the compression and heat exchange, and one or more units that are mounted on walls, floors, or ceilings inside the home. “These two components are connected by small refrigerant lines and electrical wiring that run through a small hole in the wall,” says Fagundes. 

Due to this modern design, mini splits can either be a substitute for or a supplement to an HVAC central air conditioning system. They're particularly perfect for use in older homes without adequate ductwork, says plumber and HVAC technician Alex Atkinson, as well as in home additions like converted basements and garages. They are also known for being energy-efficient and operating more quietly than their window unit counterparts.

The Advantages of a Mini Split

When weighing your options for heating and cooling your home, you'll want to understand the pros and cons of popular units. The following are a list of the many attributes of the small-yet-mighty mini split.

Heats and Cools Without Central Air

The main advantage of a mini split is that it can be installed in a home or building that does not have central forced air that relies on radiators or baseboard heating, explains HVAC expert Simon Bernath, founder of FurnacePrices.ca. In other words, mini splits are a relatively simple solution to heating and cooling a home without ductwork. 

Ability to Cool Remote Areas

Mini splits serve as an efficient way to cool areas which are not served by home ducts. Even in homes equipped with central air, mini splits can regulate the temperature of a new addition or an attic that doesn’t have adequate venting for the main central air unit to cool it as effectively.

Energy Efficiency

According to Fagundes, the energy losses associated with ductwork can account for up to 30 percent of energy use in central systems. This makes mini splits a more energy-efficient alternative to conventional central air. 

"They’re inverter-driven," Fagundes explains, "which means they can adjust their output to match the exact heating or cooling needs of a room, rather than turning on and off like older systems."

Zoned Comfort

"With a mini split, you can control the temperature in each room individually," says Fagundes. For example, you can cool your bedroom at night without cooling the rest of the house unnecessarily. This is not only an energy and money saver, but it also gives each member of the household more control over their individual thermostat. 

Easy Installation

Because there is no ductwork involved, the installation of a mini split is relatively simple, quick, and less invasive than traditional HVAC systems. "This makes them especially useful ... where extending ductwork would be costly or impossible," says Fagundes.

Quiet and Unobtrusive

While window AC units have a tendency to cause a racket, mini splits are known for their quiet and inconspicuous nature. “The indoor units are sleek, often mounted high on the wall, and operate much more quietly than window ACs or baseboard heaters,” notes Fagundes. "The outdoor unit—which houses the compressor—stays outside, minimizing indoor noise."

The Disadvantages of Mini Splits

While mini splits are advantageous for a multitude of reasons, there are downsides that are worth considering before committing to this home cooling option.

Less Ideal for Cooling Large or Multiple Rooms

For larger homes or cooling multiple rooms, mini splits are less efficient. Bernath points out that the amount of units necessary (both indoors and out) can become costly and challenging to install, when compared with a traditional central unit that cools the entire home via the ductwork. 

"A central HVAC system would be more efficient and economical if you need to cool a very large open area or a whole house uniformly with ductwork already installed," Atkinson corroborates.

Initial Cost

“Even though it’s possible to save money over time through energy efficiency, the upfront expense for the equipment and professional installation can be significant,” says Fagundes, “especially if multiple indoor units are needed to cover a whole home.” This can deter homeowners who are on a tight budget or only planning to stay for a short time from pursuing the installation of a mini split.

Aesthetic

Generally speaking, the indoor units of mini splits are in plain sight and can be aesthetically disruptive to a space. “The indoor air handlers are visible and mounted on walls or ceilings, which some people find unattractive or intrusive in carefully designed interiors,” points out Fagundes. Mini splits tend to be more noticeable than the hidden vents of a central air system. 

Of course, placement can be an influencing factor. Ceiling-mounted units, for example, are less conspicuous than a wall unit. And concealed duct designs do exist on the market, offering an attractive option to those who prefer a more subtle option.

Required Regular Maintenance

Mini splits require regular maintenance to keep them running efficiently, according to Fagundes. “The filters inside the indoor units need to be cleaned frequently, usually every few weeks,” he explains. “Neglecting this can reduce performance and indoor air quality, and may lead to expensive repairs.”

Limitations in Extreme Climates

Unless you invest in a model specifically designed for low temperatures, you are going to face challenges with mini splits in extreme climates. “Standard mini splits may struggle to produce enough heat when outdoor temperatures drop well below freezing,” cautions Fagundes. 

Your home's insulation also plays a part. “In some cases, mini splits are not capable of achieving specific temperatures in poorly insulated homes unless the energy upgrades are done,” adds Atkinson.