Mini split AC guide: How do mini splits work?

What is mini-split AC? Is it right for your house? Discover what you need to know in this homeowner guide.

What is mini-split AC? Is it right for your house? Discover what you need to know in this homeowner guide.

If you’ve been researching air conditioning options, you might have run across the terms mini split or mini-split AC

It’s a strange word for a type of HVAC system that’s becoming increasingly popular in the US, and for good reason: Mini splits are super-efficient, super-effective, and they don’t require ductwork—which means you can install them just about anywhere there’s a wall. 

Even better, a ductless mini-split system also functions as a heater in winter and dehumidifies in summer—making it an all-in-one HVAC solution. Get a mini-split system at $0 upfront cost, local rebates included. Tap here to see if your house qualifies.

(Although mini-split systems can work as AC only, we’ll be talking about all-in-ones in this guide.)

Table of contents:

First, let’s go over some mini split basics. Understanding what they are, how they operate, and how they’re installed can help you know if they’re a good solution for you.

Mini splits are super-efficient, super-effective, and they don’t require ductwork—which means you can install them just about anywhere there’s a wall. 

What are mini splits, anyway? 

A mini split isn’t a brand-new invention, although they’re increasing in popularity. In fact, mini-split AC employs the same basic technology as a regular air conditioning system—but with some crucial differences. 

  1. It doesn’t require ductwork.
  2. It works to both heat and cool your home.
  3. It’s more efficient than other HVAC options.
  4. It looks a bit different than traditional AC and requires a wall-mounted or floor-mounted unit.

Mini splits go by a couple of different names in the HVAC industry—you might hear them called a ductless mini-split system, ductless AC, a mini-split heat pump, a ductless system, or mini-split air conditioners

For simplicity, you’ll hear us refer to them mainly as mini splits and mini-split AC in this article. 

Let’s dive into how they’re different from a traditional central heating and air conditioning system.

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indoor and outdoor mini split units

Mini-split AC doesn’t require ductwork

A mini-split AC system consists of two main components:

  • An outdoor unit (which is similar to the outdoor AC compressors that you’re used to seeing), and
  • A set of indoor units that are mounted directly on the walls in strategic areas of the home. 

The wall units are then connected to the outdoor compressor via a thin conduit.

These indoor units are where the air is cooled, so there’s no need for ductwork to carry air throughout your home.

Also, because each wall unit can be programmed individually—and with a handy-dandy remote control—you get ultra-precise, room-by-room temperature control.  

Overall, mini-split AC is a pretty ingenious system that allows for multi-zone use throughout your home.

Each wall unit can be programmed individually so you get ultra-precise, room-by-room temperature control.  

For comparison, a traditional HVAC system—called a standard split—moves heat using refrigerant from the interior to the exterior through an external condenser unit, and then blows the air into your home via ductwork.

So a lot of that “cool air feeling” can be lost as air travels through the ductwork of your house and gets warmer, especially if the ductwork is older and in bad shape.

But mini splits aren’t the right solution for every house. If you live in a house with well-maintained ductwork, for example, a central air-source heat pump that can utilize your current ductwork could be a better fit for your HVAC needs. 

Mini-split AC works both ways—it cools and heats your home

Mini splits work brilliantly to cool your home, but—here’s the kicker—they can also transfer heat into your home, which means they perform the functions of both an air conditioner and a heater.

Is it time to replace your furnace or boiler? Learn what to consider when replacing old heating systems

Mini-split AC is more efficient than traditional single-zone HVAC

Mini-split heat pumps are extremely kind to the planet, and they’re an incredible option if you’re trying to cut energy waste in your home, and especially if you use them to heat your home in winter.

Because you can set up different zones in your home, you can control temperatures more precisely based on the comfort you need.

For a study of homes in the Northeast and Mid-Atlantic regions in the US, on average, houses that updated their HVAC system with a heat pump reduced their energy use by:

  • 3,000 kWh per year if replacing electric resistance heaters 
  • 6,200 kWh per year if replacing oil heating systems 

Of course every house is different, but that’s a massive reduction in energy waste (1)!

A mini-split AC system has a different look

One of the main differentiators of mini-split AC systems?

They’re going to look different than traditional air conditioning, mostly due to the fact that this kind of heat pump system requires indoor units throughout the home. 

These indoor units are sleek and discreet, so they definitely have more appeal than a traditional window unit AC. But they are more visible than a standard split system that uses ductwork. (It’s nothing a little decorating ingenuity can’t handle, though.) 

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How do mini splits work?

The basic scientific principle behind mini-split AC is this: It takes less energy to transport something than to create something from scratch. 

If you doubt this, consider the scenario of looking for a seat at an overcrowded dinner table: When there’s nowhere to sit, would you rather build a chair from scratch—or just go get a chair from elsewhere in the house?

During the summer, super-chilled liquid within your mini-split AC attracts the heat energy inside your home. Then, it simply transports that heat energy outside—making your house feel cool.

In other words, there’s no need to “create” cold air  because the ductless mini-split system makes the hot air disappear, like magic! Voila!

But the thing that makes a mini-split AC system truly exceptional is that (unlike traditional AC—which only works in one direction) mini splits can reverse the process to bring heat energy inside your home, too. In fact, they’re excellent at heating an entire home. 

And because transporting heat energy takes far less energy than producing heat energy, mini splits can be up to 3 times more efficient than a traditional HVAC system combo (2).

Check out this video to learn how heat pump technology works:

Because transporting heat energy takes far less energy than producing heat energy, mini splits can be up to 3 times more efficient than a traditional HVAC system combo.

Mini splits save energy in a variety of other ways, too. For instance, a modern mini-split AC system has variable speed compressor technology that runs at the precise speed necessary to keep your home at the perfect temperature. 

Therefore, on moderate days, there’s no need for your system to run its compressor at full speed—so it won’t. It’ll adjust to use exactly the amount of energy required. No more, no less. 

(Traditional AC systems, meanwhile, have two-stage or one-stage compressors that simply switch on and off. While these basic compressors do their job, they can waste a lot of energy.)

Also, since mini splits don’t require ductwork, all of the energy waste associated with duct losses is a thing of the past. Older, leaky ductwork can cause conditioned air to “get lost” while traveling through your house’s duct systems, and mini splits skip this step.

That’s a bigger deal than you might think, too, since duct losses can be responsible for up to 30% of your air conditioner’s energy consumption (3).

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Advantages and disadvantages of a mini-split AC system

It’s all well and good to know how mini splits work, but how do you know if they’re right for your home? 

Here’s a quick list of the pros and cons, but we’ll dig into each one of these advantages and disadvantages below. 

Cons of mini-split systems:

  • High initial cost
  • Appearance of the unit

Pros of mini-split systems:

  • Decrease in energy use
  • Flexible, customizable ductless options
  • Better comfort
  • Healthier air
  • Easy to maintain
  • All-in-one heating and cooling system

Let’s chat through the cons first.

Disadvantages of mini-split systems


Installing a high-quality mini-split system costs about the same as purchasing both a traditional air conditioning and heating system at once. In some cases, it can be far more costly, which can deter homeowners from even considering a mini-split AC system in the first place.

But cost doesn’t have to be an issue. If your house qualifies, Sealed can help you get mini splits at NO upfront cost.

And when you look at the lifetime value of a mini-split AC system, the financial picture changes dramatically. Mini splits are super energy efficient (which can cut energy waste in your home), and if they’re well maintained, they can last for 15 years or more.

Even better: Because a mini-split AC system can also heat, dehumidify, and purify your house’s air, it’s a beautifully simple and all-in-one replacement for every HVAC component in your home.

Cost doesn’t have to be an issue. If your house qualifies, Sealed can help you get mini splits at NO upfront cost. Discover how.

Appearance of mini splits

Another potential drawback of a mini-split system is that… well, it’s a bit more visible than a system that uses ductwork. 

That said, many mini-split companies are now offering units with a sleek, modern, and minimalist design. And we should be fair to mini splits, too: They’re far more visually appealing than other “add-on” AC options (such as window units). Learn how to hide a mini split here.

Advantages of mini-split systems

Better comfort

When it comes to creating a comfortable home, ductless mini-split air conditioners are a game-changer. The temperature throughout your home will be more even, and the constant circulation ensures that every corner of your home will feel great. 

Also, because each mini-split unit covers its own section of the house, you’ll get room-by-room temperature control. Which means it’s time to call a peaceful truce to any family wars over the thermostat.

The most flexible AC around

You might think your house is a tough case, but believe us: We’ve seen mini-split AC systems make even the most stubborn houses feel cool, fresh and comfortable. 

Because the technology is customizable, and can be installed without ductwork, there’s a system to fit just about any home.

If you have a period home, like a Victorian, mini splits allow for an unobtrusive HVAC system update—one that doesn’t require the risk of damage to original features by installing or repairing existing duct systems.

Easy to live with

Mini splits don’t give off strange smells, they don’t use fossil fuels, and they don’t require much upkeep. They’re also super quiet. After you install your mini-split system, you’ll likely just forget that it’s even there (except the noticeable fact that your house feels amazing).

Healthier air

Mini splits come with built-in filtration to remove particles and other contaminants out of the air you breathe. 

This can improve your home air quality and lead to better overall health for you and your family, especially if anyone suffers from allergies or asthma. 

Mini splits come with built-in filtration to remove particles and other contaminants out of the air you breathe, a healthy bonus if anyone suffers from allergies or asthma.

And they don’t burn natural gas or oil inside your home, so you won’t be exposed to emissions or dangerous carbon monoxide off-gassing.

All-in-one system

Because a mini-split system combines both heating and cooling in your home, it makes house maintenance so much easier. Instead of two (or three, or four!) separate systems, you can simply install and maintain one. Say goodbye to ugly, wasteful DIY window units.

Reduced energy costs

Mini-split systems are incredibly efficient, so your system might just pay for itself in the long run. In fact, according to ENERGY STAR, mini splits can save homeowners up to 30% on their energy bills, depending on your fuel costs (4). 

And these systems usually have a higher seer rating than conventional air conditioners and heaters.

Cleaner, more ecologically friendly energy

Mini splits are the greenest HVAC system currently on the market. They’re fully powered by electricity, so they don’t produce any carbon dioxide and, therefore, reduce your outdoor and indoor air pollution.  

They’re incredibly efficient with the electricity they do use, so you’ll significantly decrease your home’s environmental footprint (and energy waste) by installing one.

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Who should choose a mini-split AC system?

Finally, the million-dollar question: Is a mini split right for your home?

Here are a few reasons why a ductless mini splits might be the best choice for you:

If you mentally checked any of these boxes, then a mini-split AC system might be a good choice for your home.

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What mini split installation will look like

By far, the best (and least stressful) way to install a mini-split AC system is to call a trained HVAC expert. They know what they’re doing and can avoid any installation catastrophes.

More importantly, designing the right network of mini-split units is best done by someone who has years of experience making houses feel great. And if you misplace wall units or don’t have the right number of them for your home’s layout, the system won’t be as efficient.

See if your house qualifies for expert installation from Sealed.

That said, here’s a general overview of how a mini-split system will be installed in your home:

Before installation

An HVAC expert will talk with you to determine exactly what your needs are and what problems you’re trying to solve. Then, they’ll analyze the layout and specific quirks of the building—as well as the house’s overall energy waste. 

They’ll use all that data to create a completely customized mini-split AC system for you based on multiple zones throughout your house. (They may have some additional recommendations to make your home feel its best, too—such as air-sealing the tiny holes in your home’s exterior or adding some additional insulation.) 

Once you agree on a plan, the work can begin.

AC replacement: mini split indoor wall unit above a window

Inside your home

Mini-split units (sometimes called mini-split heads) will be installed throughout your house in the right places for optimum performance and comfort.

Usually, these indoor units are installed:

  • At least 6 feet above the floor 
  • On walls that lead directly outside
  • In places where they won’t get direct sunshine or be blocked by furniture or curtains 

Wherever a mini-split head is installed, the person doing the installation will drill a 2-3” hole for the refrigerant, control, and drain tubing cables—and then run all those cables through the hole so they can be connected to the main compressor. 

Outside your home

An outdoor condenser unit will be installed outside of your home, usually on a concrete pad on the ground nearby or lifted stilts if you live in an area with significant snowfall. (Sometimes the outdoor condenser can even be installed on the roof). 

Once the exterior condenser unit is set up properly in a stable location, the installer will connect the condenser to the mini-split heads and make sure everything is working properly.

And that’s pretty much it. You can now marvel at how fantastic your home feels!

Qualify for a mini-split AC system—at NO upfront cost

Sold on mini splits? We are too. And if your home qualifies for Sealed, you can get a custom home upgrade plan from experts with years of experience making homes efficient and comfortable. 

Basically, your HVAC system will be based on your house—and how you want to feel in it.

We’ll hire and manage expert contractors and make sure the work gets done right. (We’re accountable to the work actually reducing your energy waste, too.)

Answer a 2-minute questionnaire to see if your home qualifies. 

And you can get all of this work done at NO upfront cost. It’s a great system that gets great results.

Thanks to Sealed, we can finally enjoy our house’s fullest potential.

Jordan – Teaneck, NJ, Sealed customer

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FAQs about mini-split AC, ductless AC, and ductless heat pumps

Click below to jump ahead to your specific question. Or feel free to scroll and scan for what you need today!

What’s the best mini-split AC to install?

The exact model that’s right for your home will be based on your house’s unique heating and cooling needs. Our team of experts love to work with (and trust) the following brands:

Talk to a Sealed expert to determine what system might be best for your home. Or discover how you could get one at zero upfront cost.

How does ductless heating work?

Ductless heating (also known as mini splits, a ductless heat pump, or mini-split AC) is a type of heating and cooling system that doesn’t require any ductwork. It moves heat energy around, rather than producing it.

The system has an outdoor compressor unit that’s connected to one or more indoor units. It’s a setup that allows mini splits to be much more energy efficient than traditional HVAC systems, since there is no loss of heat or warm air through ductwork. 

Do ductless mini-split heat pumps work in cold weather?

Yes, mini-split heat pumps can operate in very cold weather, as long as the outdoor unit is not covered in snow or ice. In fact, mini-split heat pumps can often be used in snowy climates in the US, and they’re a pretty popular HVAC option in Maine! (And Maine is known for snowy, cold, freezing winters!)

But it does depend on how cold the weather gets where you live. Learn more about how mini-split heat pumps work in cold climates.

What are the advantages of a mini-split system?

There are several advantages of mini-split systems: 

  • Mini splits are energy efficient and can cut a lot of your house’s energy waste
  • Mini splits are an all-in-one solution—they heat, cool, purify, and dehumidify the air in your house
  • Mini splits are versatile and can be used to heat or cool individual rooms or groups of rooms
  • Mini splits can be installed in homes without ductwork
  • They’re super quiet and provide fantastic airflow—no more stuffy air

What are the disadvantages of a mini-split system?

The main disadvantage of mini-split systems is the initial cost, which can be higher than other types of HVAC systems. However, mini splits cut so much energy waste that they can potentially save you money in the long run.

In addition, some homeowners don’t like the look of the indoor unit on the wall and don’t prefer that a hole (although it’s super small!) needs to be drilled into the wall, but this is usually less invasive—and can be less expensive—than installing or repairing duct work. There are also refrigerant lines that run on the exterior of the home, although they are installed to make them as least noticeable as possible. 

How many square feet can a mini split cool?

That depends on the size of the mini-split unit you purchase and the existing conditions and layout of your home (and this will vary from house to house). But in general, the higher a mini split’s BTU rating, the more square feet it can cover. 

How big of a house can a mini split cool?

With a sufficient number of units professionally installed, mini splits can serve basically any sized home. Mini splits are a super-customizable HVAC solution.

Are mini splits noisy?

No, mini splits are very quiet and most people don’t even notice the indoor units when they’re running. However, you might occasionally hear a slight humming noise coming from the outdoor unit.

Are mini splits good for a whole house? 

Sure! A mini-split system can heat and cool an entire home with multiple mini-split heads or indoor wall units.

Keep in mind: We’re not saying that the mini split is the right solution for every house. If you have well-maintained ductwork, for example, you might be better off with a central air-source heat pump. 

But mini splits work for lots of people, and there’s a good chance that a mini-split system can work for your entire house.

Can I install a mini split myself?

Mini-split installation is a complex, technical process—and it requires an HVAC professional. (It’s pretty unpleasant to drill a hole in the wall and realize it’s in the wrong place. Not only that, but if you don’t correctly size or place your units, they won’t be as energy efficient.)

How much wall space does a mini split need?

The wall units vary in size, but most are about 12 inches by 32 inches by 9 inches, so you’ll need to make sure you have at least 3 feet of space available for your mini split (5).

Mini splits need a few inches of clearance on all sides for proper ventilation. An HVAC expert will help you correctly size and install your system, but if you’re looking to have a specific model installed and want to check the amount of wall space you’ll need beforehand, review the manufacturer’s specifications.

Can you put a mini split anywhere?

Not exactly! Mini splits need to be installed in a location where they can be properly connected to the main compressor unit. They’re usually installed at least 6’ off the ground, although floor units are available as well. And mini splits should be installed in an area where they won’t be exposed to direct sunlight, as this can cause the unit to overheat.

How do you decorate around a mini split? 

If you want to cover or hide your mini split, there are a few things you can do. But whatever you do, just make sure you don’t block the unit with fabric or any other material. Mini splits need proper ventilation to work correctly. (Ask your HVAC contractor if you have any concerns!)

Not feeling handy? Etsy has plenty of mini-split cover options. Or tap here for our guide to hiding mini splits.

Have more mini split questions? Talk to Sealed. We’re the experts. 

Sealed can help you determine if mini-split AC is a good option for your home, and not only that, we also manage the entire customized installation project from start to finish and stay accountable to the results.

We help homeowners create a better-feeling, more comfortable, less-wasteful home at no upfront cost. (If your home qualifies. Answer our quick questionnaire to find out.)

Make your home feel amazing and eliminate the expensive energy waste that shows up on your high heating and cooling bills. 

Talk to a Sealed expert today to learn how we can help your home feel incredible.

May 9, 2022