What you Need to Know About Ductless Air Conditioning

  • By: Cheli Scott
  • Date: Nov 24 2022

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What you need to know about ductless air conditioning

There are a different types of air conditioners available on the market, but many consumers are unfamiliar with ductless air conditioning systems. A ductless air conditioner, as the name suggests is an air conditioning system that does not use ducts to move air through your home.

Ductless air conditioners or “mini split” systems use wall or ceiling mounted units to cool your home. Unlike window units, which also don’t use ducts, ductless air conditioning systems tend to have more aesthetic appeal, while still saving you money on a full ducted HVAC system.

mini split air conditioner

How do ductless air conditioners work?

Ductless air conditioners consist of two units, an indoor unit and an outdoor unit. Inside your home, is the blower unit. This part of the air conditioner gathers warm air from your room and replaces it with cool air.

The outdoor unit is the condenser. This part of the air conditioner takes the heat from your home and releases it outside. The two pieces are connected by a conduit that can be run through a wall.

If you want to cool an entire suburban house, you may find you need more than one indoor unit to provide adequate cooling. Mini split air conditioner systems are split into two configuration options; single-zone and multi-zone.

a ductless air conditioner in a nice living room

Single-zone mini-split ductless air conditioner

A single-zone system has one outdoor unit and one indoor unit that usually provide air conditioning to one area. These systems are ideal if you only need air conditioning in one room like a sunroom or a workshop. They can be especially helpful if you want to expand an existing HVAC system without investing in additional ductwork.

a ductless air conditioner in an office

Multi-zone mini split air conditioner

A multi-zone system has one outdoor unit attached to multiple indoor units. This system is ideal to cool an entire home or multiple areas in a home that a single-zone control wouldn’t adequately cool.

a mini split system in a living room with a high cieling

What size ductless mini split system do I need?

One of the benefits of mini split air conditioners is that they are very customizable. In order to expand them, you really only need to obtain more indoor units. However, depending on the size of your home, it may be confusing to figure out what size you need.

The best course of action is to call an HVAC professional. They will be able to assess the conditions of your home and make a recommendation on the size mini split air conditioner you need to properly cool your home. Getting a system that is too small for your home can cost you more in the long run, causing more wear and tear on your machine.

The cooling capacity of air conditioners are measured in BTU or British Thermal Units, which measure the amount of heat that is needed to raise or lower one pound of water by one degree. In order to heat and cool your home properly you will need an air conditioner that is rated for the size of your home.

Carrier suggests to figure out what BTU you need multiply the square feet of your room by 25. For this type of system you will need to repeat the calculation for each room you plan to cool. However, it’s not wise to stop there.

The square footage isn’t the only thing that matters in this calculation. An HVAC technician will also take into account how many people frequent a room as well as the height of the ceiling among other factors.

For example, if the room that you want to cool is very sunny you will need to increase capacity by 10%. If the room is shady, you can lower the capacity needed by 10%.

As you can see it can get a little complicated, so for the most accurate measurement, trust an experienced professional.

What are the benefits of a ductless air conditioning system

There are many benefits to a ductless air conditioner over a central air conditioning system, but many of them are unique to your situation. Below we’ve summarized the main benefits to this type of system.

a new ductless air conditioner in a new home

No Ductwork

One big benefit of a mini split air conditioner is that you don’t have to buy or maintain a ductwork system in your home to keep it cool. Ductwork can be a costly investment if it doesn’t already exist in your house. According to Fixr, it costs $12,000 to add a new ductwork system to an existing home. That’s a big chunk of change.

a mini split system in a bedroom

DIY installation

A mini split air conditioner can also be installed by the homeowner, so you don’t have to pony up for a professional installation. The hole necessary to connect the indoor unit to the outdoor unit doesn’t need to be any bigger than 3 inches in diameter, so it doesn’t require any special construction to install.

Though the instructions to installing a mini split air conditioner vary from machine to machine, the general process is the same for most. You will mount the indoor unit about six inches away from the ceiling to give the system adequate room to move air.

Then, you can drill a small hole in the side of your home to feed the cables outdoors, where you will install the outdoor unit. The outdoor units generally need a few feet of clear space around them for proper ventilation and for safety.

There are many how-to videos online explaining how to complete this process for many of the different kinds of machines on the market.

Some ductless air conditioners advertise being easier for DIY installation than others, so it’s wise to review the training videos of the machine you are thinking about purchasing before you hit “buy”.

If you don’t feel comfortable installing it yourself an HVAC technician can also install these systems professionally.

a mini split being installed

Energy Efficiency

It may be surprising, but your ductless air conditioner is 20-30% more efficient than a central air conditioning system. Some efficiency in a central air conditioner is lost through ductwork. Since mini split systems are ductless, they don’t have this problem.

Mini split systems also function as heat pumps, providing warm air in the winter. This saves you money and energy on purchasing an additional unit to heat your home, as well.

a mini split in a nice bedroom


Because mini splits are easy to install and can be purchased for individual rooms, they are very flexible. A single air handler can cool more than just one room, depending on your unique conditions, so you may find you need fewer indoor units than you are expecting.

Since mini splits aren’t connected to a central air system by ductwork, they are great for cooling odd rooms like a sunroom or a den that was added after the initial construction of the home. DIY installation makes them easy to purchase and set up in a pinch, as well.

What are the cons of mini splits

While mini split systems work great for certain conditions, they are not for every situation and they have some cons. We’ve listed the most notable ones below.


Mini splits on average have a more expensive initial cost than central systems. Usually, your home already comes with ductwork, so unless you need add a room onto your home, you may not be worried about the cost of ducts at all. Additionally, depending on the size of your home, you may find you need several indoor units to adequately cool your home. These costs start to pile up.


Ductless mini splits offer no additional ventilation to your home, because they don’t utilize ducts or vents to move fresh air into your home. Instead, they condition the air that is already there. Since they offer no additional ventilation, you can’t rely on them to provide any sort of air purification and you may need to seek out other appliances to serve this purpose.


These systems require individual air handlers to heat and cool a room, so in a large home one or two units may not be enough. It can become prohibitively expensive to purchase these units for larger suburban houses with many rooms, attics, and basements.

Time to Buy

As you can see, for some homeowners and renters a mini split is an ideal solution to their heating and cooling needs. Don’t be afraid to get your hands dirty and install a ductless system yourself. However, if the whole process seems too confusing, it’s time to call in a professional like the ones at bhild.com. Call us today, or fill out our form here for a free estimate on HVAC services!

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