How Does a Ductless Mini-Split Work?

Ductless mini-splits are increasingly popular heating and cooling options worldwide. Many countries and regions have used them – or units similar to them – for years, while others are

In this article we’re going to cover the basics of how mini-splits operate. 

This is more than just a dry explanation of the technical aspects of HVAC, though (although we think the science behind it is pretty neat too!). We’ll also discuss who should be interested in a ductless system and the benefits of having one.

Basics of Ductless Mini-Splits

You’ve seen a ductless system even if you don’t realize it. While there are different sizes and types, the most common is a roughly rectangular capsule that is positioned on the wall of a room.

At the bottom of this capsule are controllable vents where air comes out of, and the unit pushes cool air into the area.

Or warm air. It’s a little-known fact that many mini-splits can both heat and cool. While some models only cool, and this is what many are primarily installed for, having the comfort of both heating and cooling from a ductless system can make the area more comfortable all year long, not just in the warmer months.

Ductless units are not only this capsule. They have a line that runs to an outdoor unit, usually close to the sides of the home, near the area where it’s installed inside. We’ll discuss these more in the next section where we break down the parts of a ductless system.

Lastly, as the name implies, ductless equipment does not require home ductwork to function. This is the primary difference between ductless units and traditional home cooling systems.

Parts of a Ductless Mini-Split

The indoor (evaporator) and outdoor (condenser) units are the two primary parts in a ductless system. To leave it there, though, would be to ignore the sophistication of this equipment.

The indoor unit has an evaporator coil, fan and filter. There may also be a condensate pump attached to the unit, depending on its location in the home. These are somewhat rare, but can be necessary for proper removal of moisture.

Outside, is the condensing coil and another fan to blow air out of the unit.

A line set runs between the two. This line includes a refrigerant line, electrical wiring, and insulation. A protective covering may be placed over the line set as well (sometimes called “line hide”). This can also be useful to avoid the eyesore of the line set running alongside your home. The line set protector can be painted to match the home, effectively masking the line.

The Cooling Process

The actual cooling process is remarkably similar to that of a traditional, whole-home air conditioner. The only major difference is the lack of ductwork.

In brief, though, the cooling process involves a series of cyclical steps:

1. Warm air passes over the evaporator coil in the indoor unit. Heat is absorbed by this coil.
2. The heat travels through the refrigerant line, which is pressurized to transition between liquid and gaseous states.
3. Once outside, the refrigerant changes states and emits the heat, which is then expelled via the outdoor unit’s fan.
4. This process continues until a target temperature is reached that’s been set on the system’s thermostat.

There’s a lot that goes into ensuring that that all runs smoothly, but that process covers the basics of cooling.

For heating, much like in a heat pump system, the process is the same but in reverse, with heat being absorbed from the outdoor air and transferred inside.

What’s the Difference Between Standard A/C and Ductless?

We touched on some of this above, but to reiterate, the most obvious differences are:

1. Lack of ductwork needed for ductless
2. The area that can be effectively cooled or heated by a ductless system

Ductless mini-splits can be installed nearly anywhere in the home, so a series of ductless units could indeed cool or heat an entire home. There are occasionally even benefits to this!

However, even the most powerful ductless system can’t handle entire homes. More often, they’re used for specific rooms or areas, which we’ll discuss in more detail below.

Cooling Capacity of Ductless Units

The cooling capacity of ductless mini-splits is generally based on square footage of a room. Ideally, this room can be sectioned off with doors or other barriers so that there isn’t a ton of energy loss to other areas of the home.

The smallest mini-splits are generally rated for around 400 square feet. Larger units can handle up to around 1,300 square feet.

It’s possible to install multiple heads – which is to say, multiple indoor units – attached to one or more outdoor units. In these instances, the square footage of “multi-head” ductless systems can be a lot higher, and the only limit is how many of them you have installed.

When Do You Want a Ductless Mini-Split?

So what’s the use-case for these? You’re probably already familiar with several, though a couple may surprise you:

1. Livable attics, those that lack ductwork and struggle to stay cool in the summer.
2. Finished basements, where there’s no dedicated ductwork running to each area.
3. Garages, perfect for when you do a lot of work in your garage and it’s in danger of being too hot or cold at different times of the year.
4. Home office, for staying comfortable as you work remotely.
5. Room additions, areas that have been added to the home after it was originally built and may lack the infrastructure for full ductwork.
6. Master bedrooms, which are often the further rooms from the home’s HVAC system and can struggle to stay comfortable year-round.
7. Guest rooms and living quarters. If you have a separate, livable area that’s unattached to your main home, mini-splits can keep the air conditioned.
8. Slab homes without ductwork. Some homes were not built with ductwork in mind, and the cost to retrofit ductwork into the home would be enormous. Ductless can be a better option in these instances.

These aren’t the only times you may be interested in a ductless system, but they cover the most common.

Benefits of Ductless AC Units

You are probably already imagining some of the benefits from that list of uses above. Many should be obvious. However, there are additional reasons why ductless units can be an amazing investment in your home or other livable space.

One, it can be cheaper than installing new ductwork. To be clear: professionally-installed ductless systems aren’t cheap. HVAC is a major investment any way you slice it. But the difference between a ductless installation and new ductwork could be several thousand dollars.

Two, it can turn a two-season room into a four-season room. That finished attic might reach 100 degrees in the summer. A ductless system can allow you to use it again. Many similar examples could be found.

Three, ductless is extremely efficient. You might be familiar with SEER Rating for air conditioners, a measure of their efficiency. 20+ SEER for whole-home air conditioners are among the best on the market. But for ductless, that number could be over 30!

There are other, more minor benefits, like dehumidification in the area, which is potentially great for basements and guest homes. And air filtration, which isn’t as good as a traditional furnace filter but is better than nothing. These aren’t going to be the ultimate reason you install a mini-split, but they’re nice perks.

Conversely, a traditional, ducted system is going to be more cost-effective for your entire home compared to installing numerous ductless units. If you have ductwork in your home, and don’t have specific rooms in need of ductless comfort, you’re better off without a mini-split.

CABS Heating & Air Conditioning: Your Ductless Experts

CABS has helped thousands of homes with their comfort needs, and offers free consultation and quotes on all types of HVAC systems.

Not sure if a ductless mini-split is your best option? Not a problem. We can walk you through all of your options, provide no-obligation pricing, and allow you to determine the best fit for your home.

What are you waiting for? Call today!