Ductless Air Conditioning Buyer’s Guide for Homeowners

Ductless Air Conditioning Buyer's Guide for Homeowners

Thinking about buying a ductless air conditioner system?

You probably have plenty of questions, and I don’t blame you!

Ductless air conditioning is a fantastic solution – but it’s important to make sure you get the right one for your home.

The good news is that you’re in the right place. We here at Appliance Analysts —combined— have decades of HVAC and appliance experience!

In this article I’ll cover everything you need to know about ductless air conditioning, and arm you with the info you need to choose the best option for your home.

First up, to avoid confusion, ductless air conditioners are also known as mini splits, and we may use that term interchangeably. They’re called mini splits because they have two parts—one inside and one out.

And since whatever you call them—ductless or mini split—this type of AC may be unknown to you, we’ll start off with a little ductless/mini split 101.

What are Ductless Mini Splits?

One of the reasons—in my opinion—that ductless ACs are called mini splits is because of their size. Especially when compared to a huge central AC unit, or even a window or portable air conditioner, for that matter.

Mini splits are compact units broken out into two components—one for the inside and one out. Except, depending on the system, you can have multiple indoor units attached to a single outdoor unit.

The outdoor unit contains the condenser and compressor, and the indoor unit is the air handler. They’re attached by a conduit that’s run through an exterior wall, and it houses the cables and tubes necessary for power, refrigerant, and condensate drain.

Types of Ductless Air Conditioners

One of the best things about going ductless is the versatility. Depending on your home and needs, there are several options.

  • Wall mount
  • Floor mount
  • Ceiling recessed

Wall Mount

Mini Split Installed
Wall Mount Mini Split

Since this is the most popular type, you’ll have lots of choice when shopping. They’re mounted close to the ceiling and airflow is pushed down into the room.

Floor Mount

Despite being called a floor mount, these aren’t installed on the floor. They’re still installed on the wall, but instead of near the ceiling, they’re near the floor and airflow is pushed up into the room.

One advantage of this type is they’re easy to get at for cleaning and maintenance.

Ceiling Recessed (Cassette)

First, in order to install these, you’d need at least 10 inches of clearance above the ceiling where you want it to go. The housing is installed above the ceiling and pushes the conditioned air in four directions at once.

And then we break those down a little for some other options.

  • Single zone
  • Multi zone

Let’s talk a bit about the attributes of each.

Single Zone

This is a single indoor air handler attached to the outdoor unit. 


If you want to cool more than one room, a multi-zone mini split can have up to four air handlers attached to the outdoor unit. Each indoor unit can function independently of the others.

Ductless Mini Split Buying Considerations

Now that you know what a mini split or ductless air conditioning system is and the types available, let’s talk about all the things you need to consider before making a purchase.

Indoor Unit Placement

In order for a mini split to work properly and efficiently, the indoor unit should be installed somewhere that allows for the best airflow. You’ll also want to be sure you have easy access so you can change the air filter when necessary.

Most importantly, it needs to be placed in a spot that allows the installer to connect it to the outdoor unit and allows the condensate drain to work properly. Additionally, the outdoor unit needs a solid level surface that allows for sufficient clearance and is close to where ever you want to put the indoor unit.

Here are a few placement guidelines.

Install on an exterior wall. Ideally, your indoor unit should be placed on an exterior or perimeter wall. While this isn’t a hard and fast rule, it is the best option, since it allows for the best — most direct — connection between the indoor and outdoor unit. And since you also have to consider and make allowance for condensate drainage, a more direct path is optimal.

If you must install an air handler on an interior wall, be aware that it will increase your installation costs since the hookup will be more complex when it comes to electrical connections and how the refrigerant line is installed. Additionally, since you don’t have a direct path between the indoor and outdoor units, you’ll likely need to have a condensate pump installed as well.

Avoid electronic devices. If you install the indoor unit near anything that generates heat such as computers, televisions, or light fixtures, your air conditioner may lose its ability to gauge interior temperatures.

Make sure you have a direct path. Don’t place your indoor unit anywhere where airflow could be blocked. This could include furniture, wall hangings, shelving units, or anything else.

Allow for optimal air distribution. Pairing this with the need to install your air handler on an exterior wall may present something of a challenge, but you want a location that allows for the best air distribution to the entire room.

If you’re considering a wall mount ductless air conditioner, they need to be placed between 6 and 7 feet from the floor and not too close to the ceiling. However, each manufacturer will have their own guidelines and recommendations, so be sure to follow those.

Install vertically. Your wall mount mini split should never be installed on the ceiling or on an angled wall. It must be installed on a vertical wall only and should be secured to studs.

Outdoor Unit Placement

While there aren’t as many outdoor guidelines as there are indoors, there still are a few important things to consider.

Municipal bylaws. Be sure to check any local bylaws around outdoor air conditioning units and follow them.

Avoid obstructions. This could be bushes, shrubbery, or anything else. Much like a more traditional central air conditioner unit, it needs maximum airflow, so be sure to allow for several feet of space around the unit. It’s also best to have the unit a few inches above a pad to allow for drainage in the heating season.

Level surface. Whether it’s on a concrete or composite pad, your outdoor unit needs to be sitting on a solid, level surface.

Rooftop or wall mount. The outdoor unit can be placed on either, and in the case of wall mount it must be done with specifically designed mounting hardware.

Distance from the house. Outdoor units can be placed up to 100 feet away from the indoor unit but the farther away they are, the more they’ll cost you to run since the distance causes them to lose efficiency.

Cooling Capacity

To calculate cooling capacity — the size of air conditioner you need to purchase — you need to know the square footage of the room or area that you plan to cool. Which is exactly the kind of information you need when sizing any type of air conditioner – but there’s one more thing to think about. Whether you have a single-zone or multi-zone mini split.

The BTU output of the outside unit and the inside air handler is the same if you are looking at single-zone systems. However, a multi-zone system will differ in that the outdoor unit will be a multiple of the individual indoor units.

For example, if you have an outdoor condenser with an output of 40,000 BTUs, you could have four indoor air handlers with 10,000 BTUs each. But since individual rooms in your home are likely of different sizes, it’s not necessary for their corresponding air handlers to have an equal number of BTUs.

While it’s always best to have a professional calculate cooling capacity, the following will provide you with a guideline.

Room or Area You’d Like to CoolNecessary Cooling Capacity
150 to 250 sq ft6,000 BTUs
250 to 300 sq ft7,000 BTUs
300 to 350 sq ft8,000 BTUs
350 to 400 sq ft9,000 BTUs
400 to 450 sq ft10,000 BTUs
450 to 550 sq ft12,000 BTUs
550 to 700 sq ft14,000 BTUs
700 to 1000 sq ft18,000 BTUs
1000 to 1200 sq ft21,000 BTUs
1200 to 1400 sq ft23,000 BTUs
1500 and above sq ft24,000 BTUs

Why do we say a professional is a good idea? Because calculating cooling capacity includes more than simply square feet.

Environmental Factors

An important part of the cooling capacity equation is environmental factors. Any and all of the list below are factored into the equation and either increase or decrease the number of BTUs required.

  • Ceiling height
  • Climate
  • Electronics and appliances that create heat
  • Insulation
  • Windows — do they get direct sunlight?

For further information on how environmental factors impact cooling capacity, please refer to the Energy Star website.

Installation Cost

For the most part, if you’re purchasing a window air conditioner or a portable air conditioner you can install it by yourself. However, you typically need a professional to install a mini split, and that can cost anywhere up to $2,000 per zone — just for the installation.

Be sure to factor that in when calculating costs.


When it comes to central air conditioners, you don’t see anything in your living space. Unless you’re in your basement or somewhere outside, you don’t see the condenser or the air handler.

Keep in mind though, the air handler of a mini-split is essentially going to become part of your decor. Each room that you’re cooling will have a wall unit, either at the ceiling or at floor level. For many people, this will be a turn off. But if you’re hot, and you can’t install central air, I bet most people would move beyond their distaste fairly quickly.

Choosing Your Ductless Air Conditioner

We can’t tell you which ductless air conditioner is best for you. Only you can do that. But we have provided you with most, if not all, of the information you need to make an informed decision.

So go through each of the considerations mentioned above and evaluate what they mean to you if anything.

For example, can you stand looking at air handlers on your wall? Some people will care, and some won’t.

Think about the price to purchase and install. Can you afford to spend upwards of $9,000 depending on the system you need? Or would you be better off installing a few portable or window air conditioners?

Do you have usable space both inside and outside for air handlers and condensers? And remember, there are stipulations on where the outside condenser can be placed. Make sure you can work within those guidelines.

And finally, if and when you decide that a ductless mini split is the right choice for you, be sure to do your due diligence when it comes to installers. Don’t just hire the cheapest. Get some quotes, check reviews, and hire an HVAC company that will do the job right.

Frequently Asked Questions

What are the disadvantages of ductless mini-split systems?

They can cost just as much as a traditional central air conditioner. Additionally, it’s very important to size your system correctly, otherwise, your system will short cycle, leading to increased costs and an inability to efficiently control temperature or humidity.

What is the lifespan of a ductless mini-split system?

10 to 30 years, so an average of 20 years.

Do mini splits require annual maintenance?

Yes. Failure to do so may void your warranty.

Hi there! I’m Craig, and I’m the founder of Appliance Analysts. When it comes to appliances and anything electrical, I’ve always loved opening things up, figuring out how they work, and fixing them. This website is where I share free advice from myself and our experts to help our readers solve their appliance/HVAC problems and save money. Read more