What is a Mini-Split?

A mini-split, also known as a ductless air conditioning system, is a compact HVAC system that can efficiently heat and cool single rooms, small apartments, and other spaces where ductwork isn’t practical or feasible. Like standard heat pump-based systems, a mini-split consists of two primary components: an outdoor compressor/condenser unit and one or more indoor air handlers.

Because of their size and relative simplicity, mini-splits are ideal for use in new additions to a home and as a solution for multi-family housing where several smaller units are called for. They’re also a great option for improving the heating and cooling capabilities of homes that are equipped with “non-ducted” systems such as hot water or radiant panel heating.

You can visit our mini-splits system page to learn more and explore our available mini-split models.

The popularity of mini-split systems has grown in recent years due to their energy simplicity, efficiency, and versatility. But how do they work?

How Does a Mini-Split work?


Shipped fully assembled, mini-split installation is far easier than most systems, typically only requiring a single 3-inch hole in the outside wall or ceiling to connect the outdoor and indoor units.

Once installed, the compressor unit and the indoor air handler are connected by 2 small refrigerant pipes and power and communication wiring – all routed through that single 3-inch hole. This direct connection allows the units to constantly share information on indoor and outdoor conditions, boosting efficiency and allowing the system to optimize its performance based on your settings.

Those settings are handled by the mini-split’s third component – a controller in the form of a remote control or a wall-mounted thermostat. Just like a conventional system, this controller allows you to adjust the temperature, fan speed, timer, and other settings from a distance. Depending on the specific mini-split model, you may also be able to control your mini-split using voice commands or over Wi-Fi through a mobile app.

 Operation modes and settings

When in cooling mode, a mini-split system reduces the indoor temperature by extracting heat from the indoor air and transferring it outdoors. When the thermostat is lowered, the refrigerant in the indoor unit’s evaporator coil begins absorbing heat causing it to evaporate, resulting in condensation on the coil. The air handler’s fan blows air over the coil, cooling it and distributing into the space.

For heating, the mini-split system operates in reverse. The system extracts heat from the outdoor air and transfers it indoors. The outdoor unit's compressor pressurizes the refrigerant, causing it to release heat, warming the indoor coil. The indoor unit's fan blows air over the heated coil, distributing warm air throughout the room.

Basically, a mini-split performs all the same functions of a conventional whole-home system on a much smaller scale – all without the need for duct work or complicated installation.  

Are There Different Types of Mini-Splits?

Yes and no. While from a functionality perspective, all mini-split systems are basically the same, there are configuration options that make the mini-split a flexible choice. There are 3 configuration technologies that go into to “designing” a system that meets a buyer’s specific needs.

Single-zone vs. multi-zone mini-splits

Mini-splits come in two main configurations: single-zone and multi-zone. Single-zone mini-splits are designed to cool or heat a single room or area, making them an excellent choice for small spaces or individual rooms. On the other hand, multi-zone mini-splits have the capability to cool or heat multiple rooms or areas simultaneously, using a single outdoor unit and multiple indoor units. This makes them ideal for larger spaces or homes with multiple rooms.

Ducted vs. ductless mini-splits

Mini-splits can also be categorized into ducted and ductless systems. Ducted mini-splits utilize a network of ducts to distribute conditioned air throughout the space, similar to traditional central HVAC systems. These systems are ideal for homes or buildings with existing ductwork. As the name implies, ductless mini-splits do not require any ductwork and are installed directly in the room or area that needs to be cooled or heated. These systems provide greater flexibility in terms of installation and are often more energy-efficient.

Wall-mounted vs. ceiling cassette mini-splits

Another aspect to consider when choosing a mini-split system is the installation style. Wall-mounted mini-splits are the most common type and are installed high on the wall, providing efficient and even air distribution. Ceiling cassette mini-splits are installed in the ceiling and distribute air downwards. These systems offer a more discreet appearance and can be a great choice for rooms with limited wall space.                                                                         

Benefits of a Mini-Split system

With the right application, mini-splits have some obvious benefits.


  • Flexibility and Ease of Installation

Mini-split systems offer flexible configuration options, making them suitable for a variety of spaces. Plus, with no need for ductwork, mini-splits can be easily installed in older homes, small apartments, additions, or areas with limited space. Installing a mini-split can be as simple as cutting a single hole in the wall where the system will live, eliminating the expensive, time-consuming installation requirements that come  with a conventional system. 

  • Efficiency and Cost-Savings

With efficiency ratings of up to 28.1 SEER2 and 11.9 HSPF2, Lennox mini-split systems deliver cost-savings along with convenient comfort – and may even make you eligible for incentives and rebates. Installed properly, the addition of a mini-split system can help cut your energy bills by hundreds of dollars a year.   

  • Improved Indoor Air Quality

In keeping with our Pursuit of Perfect Air, Lennox mini-split systems feature advanced filtration technology that helps improve indoor air quality. The filters trap and remove dust, pollen, allergens, and other airborne particles, creating a healthier more comfortable living or working environment.

  • Multi-Zone Comfort

One high-efficiency outdoor unit can support up to five indoor comfort zones, offering you a customizable and energy-efficient whole-home heating and cooling solution.

  • Minimum Noise

Built-in features and technologies keep noise to a minimum. Indoor units operate as low as 20dB which means they are literally whisper quiet. Our outdoor units operate as low as 53dB – roughly the sound of an electric toothbrush. 

The Downsides of a Mini-Split

Despite their benefits, there are some drawbacks to choosing a mini-split vs. a conventional system.

  • Higher upfront cost

Mini-split systems generally have a higher upfront cost compared to traditional HVAC systems. Typical upfront cost-per-ton of cooling capacity can run as much as 30% higher than a conventional system – and more than twice the cost when compared to window units of similar capacity. However, it's essential to consider the long-term savings in energy costs and the overall efficiency of these units.

  • Limited capacity

Mini-splits are designed to cool or heat specific areas rather than the entire home. If you have a large space or multiple rooms that require cooling or heating, you may need to install multiple units, which can increase the overall cost.

  • Professional installation required

Unlike portable air conditioners or window units, mini-split systems require professional installation. This ensures optimal performance and proper function. It's best to consult with a qualified HVAC technician who can assess your specific needs and provide expert installation services. 

How Do I Know if a Mini-Split is right for my space?

When it comes to cooling your home, you may be choosing between a mini-split system and central air conditioning. Compared to central air conditioning, mini-splits are more energy efficient and offer better zoning capabilities. They also typically require less invasive work to install and are easier to maintain, making them a great option for homes without existing ductwork, for room additions or for supplemental heating and cooling needs.

As we covered, mini-splits are energy-efficient, easy to install, and provide a lot of design flexibility. They do however need to be applied correctly to maximize the benefits. If you think a mini-split might fit your needs, reach out to one of our expert technicians to help you determine if a mini-split is right for you. They will guide you through the process of selecting and configuring the appropriate model and configuration for you and your path to perfect air. Find a Lennox dealer today.

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