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What Is a Ductless Mini-split HVAC System?


When most people think about HVAC systems, they think of two things: giant central systems or small, self-contained units like radiators and window units. Ductless mini-split systems are a third, often overlooked option. Ductless mini-split systems have been popular across the world for years, but they’ve only recently gained traction in the US. According to trade publication Oil and Energy Online, the ductless mini-split market grew 221% over just seven years. But what exactly are these innovative HVAC systems and, more importantly, what are their advantages?

Ductless Mini-split Systems: It’s All in the Name

A ductless mini-split system, or ductless HVAC system, is exactly what the name implies: it’s small, contains no ducts and heats and cools rooms. Let’s break that down a bit.

There are three main components to a ductless mini-split. The first is an outdoor unit called a compressor or condenser. When it’s hot, a condenser releases hot air from inside a home to the outdoors. When its cold, it collects heat and releases it indoors.

The condenser’s indoor counterpart is called an evaporator or air-handling unit. It’s the part that blows either hot or cool air across a room. In a mini-split system, these parts are smaller than in a conventional central HVAC system, hence the mini part of the name.

The indoor and outdoor units are connected by refrigerant lines, electrical cables and drain lines. Because the indoor and outdoor units are directly connected, they are ductless. In a conventional HVAC system, they’re connected by ducts with multiple vents.

This may sound like a complicated version of a window unit or heater, but it’s a little more dynamic than that. Because the indoor and outdoor units are split, the same outdoor unit can control multiple indoor units.


Types of Ductless Mini-split Systems

Though they’re relatively simple systems, ductless mini-splits can be installed in two configurations depending on a building’s HVAC needs:

  • -Single zone mini-splits control the temperature of one room using one outdoor unit and one indoor unit.
  • -Multi-zone mini-splits use one outdoor unit connected to multiple indoor units. Each indoor unit can be installed in a different room and controlled independently of the others.

Indoor units can be placed in different places to maximize efficiency. They can be installed:

  • -Near the top of a wall. This is often the most popular and economical choice.
  • -Near the bottom of a wall. This is ideal for homes with large windows or low ceilings.
  • -On the ceiling. Known as a ceiling cassette mini-split system, this system offers a wide air flow and keeps indoor units largely out of sight.

Advantages of a Ductless Mini-split System

Along with being a simple yet flexible HVAC solution, ductless mini-split systems offer a wide range of benefits not found with other types of home temperature control.

Zone Control

Each indoor unit allows you to independently control the temperatures of multiple rooms. This is perfect for large homes where one side receives a lot more sunlight than others. Many models come with remote controls.

Multiple Temperature Sensors

Along with remote controls, some ductless HVAC systems come equipped with temperature sensors attached to each indoor unit. This means each unit will stabilize a room’s temperature automatically.

Easy Installation

Ductwork often requires mass renovation. Ceilings and walls must be torn out, turning your home into a dusty mess. A ductless mini-split system typically only requires small holes to run refrigerant lines to each indoor unit. Generally, these holes only need to be a few inches around.

Many Installation Options

With traditional ductwork, homeowners are pretty much stuck with limited options. Ducts and vents can only go where they fit. With a ductless system, your vents can go just about anywhere.

Less Energy Loss

According to the US Department of Energy, traditional HVAC systems lose up to 30% of their energy through ducts. Because of gaps and leaks, cold air doesn’t stay as cold and warm air doesn’t stay as warm. Ductless systems avoid this problem by having a direct link between condensers and evaporators.

Dual Uses

A ductless mini-split system may be smaller than a central HVAC system, but it still heats and cools. If your home relies on radiators and window units, a ductless HVAC system is an often safer way to do both of their jobs in one unit.
Less Noise

Because of their smaller size, ductless condensers are typically a lot quieter than larger ones. With a window unit, the condenser is usually inside the unit itself meaning as it cools the air, it rattles and whirs feet away from beds and workspaces. Ductless condensers are outside so their noise is virtually unnoticeable.


Where Should I Install a Ductless Mini-split System?

Due to their versatility and size, ductless mini-split systems can be installed in just about any home or business. However, in certain spaces and renovation projects, their utility is especially helpful.


Because of the high concentration of gas vapors and other pollutants, it’s illegal to run your home’s ductwork into the garage. If your garage is made of concrete blocks or corrugated metal, it can get very hot. Since ductless mini-split systems contain no vents or ducts, they’re perfectly suited to garages.

Old Retrofitted Homes

Replacing or installing ductwork in old homes can destroy the things that make it charming in the first place. With a ductless HVAC system, you can cool and heat an old home while preserving its antique wood floors, light structures and original accent pieces.

Multi-family Homes

Central air isn’t practical for multi-family homes. Their heat pumps and condensers are often oversized and wear out quickly. With a ductless HVAC system, every family in a large building can maintain comfortable indoor climates without overworking the system.


Looking for a Ductless Mini-split System in Chicago, IL?

Since 1968, King Heating, Cooling & Plumbing has been serving homes in Southern Chicago and Northern Indiana, with superior HVAC repair and installation. Our team of professionals is well-trained in making your home a more comfortable place while also answering all of your questions. If you think a ductless mini-split system will enhance your home, contact us today. We’ll help you discover the right system for your home and budget.