A homeowner laying on his living room couch uses a remote to adjust the setting of the mini-split air handler on the wall above

Mini-splits are an eco-friendly heating and cooling option for your home. We all need to be using eco-friendly HVAC technology if we are to reach the internationally agreed target of achieving net-zero carbon emissions by 2050.

Have you heard that you could replace your old tired central air system with a ductless mini-split, but you’re not sure whether you need one in every room of your home?

We talked to a friend of ours the other day who was in the same situation. His house is not that big, but he wants to separately control the temperature in different rooms so he can keep his bedroom cooler than his kids’ rooms.

Luckily for him, this is what mini-splits are perfectly designed for. They heat and cool your home via indoor air handlers (or head units), and you can independently control them to maintain each room at a comfortable temperature.

In this article, we’ll share some insights and rules of thumb that will help you better understand how mini-splits work and what you need to think about when designing your new system. By the end, you should have a much better idea of whether you need a head unit in every room, one for each level of your house, or whether you only need one for your entire home.

Do You Need a Ductless Mini-Split In Every Room of The Home?

Mini-splits provide heating and cooling via indoor head units that blow hot or cold air to keep the temperature in the home at the desired level. Provided there is sufficient airflow between the rooms in a zone served by an individual head unit, you won’t need one in every room.

There’s a lot to consider when installing any new HVAC system, and a mini-split is no exception.

If you have doubt about what size of system you need for your house, how many head units you need, or where they should be located, you should get professional advice from a qualified HVAC technician.

What Is a Ductless Mini-Split?

A mini-split heat pump can heat or cool your home and comprises two main parts, an outdoor unit (called a compressor or condenser) and one or more indoor units. The two components are connected by line sets, which contain refrigerant fluid. Electric cabling also provides power and allows the outdoor unit to communicate with the indoor units.

The outdoor compressor pumps refrigerant fluid around the system. The refrigerant is the medium that collects and moves the heat around the system and makes heating or cooling possible.

The outdoor compressor component of a ductless mini-split

Homeowners can independently control each head unit inside the home to maintain the desired temperature in the room or zone that it serves.

A zone could comprise one or more rooms and is a way of designing the system to make optimal use of the head units and provide conditioned air where it’s needed without installing one in every room.

How Does a Ductless Mini-Split Work?

A mini-split will heat and cool your home more efficiently than traditional methods, such as electrical resistance heating or central AC. It does this using the refrigeration cycle principles to move heat instead of generating it directly as an electric resistance furnace would do.

A heat pump collects heat from the cold side of the system and moves it to the warm side. In cooling mode, the cold side is inside your home, and in heating mode, the cold side is outdoors.

Normally, heat flows from hot to cold. However, a mini-split heat pump uses electrical energy to move heat against this natural flow direction, taking advantage of the refrigeration cycle.

Do You Need a Head Unit in Every Room?

Now, bearing in mind that the head units blow the conditioned air into the home, you might be tempted to install a head unit in every room of your house.

However, that might not be the best idea.

If you have an open-plan home and it’s not too big, you can set up the air handler to blow conditioned air along the whole house. We’ve seen this work well for both heating and cooling in a narrow, open-plan home.

A mini-split system's internal air component above two doors near the ceiling of the room

A good rule of thumb is that you probably only need one unit if your home is less than 1,800 square feet and a single level. However, if your house is on two levels, you’ll need another air handler to have one covering each floor.

Mini-Splits are Flexible

One of the great things about mini-splits is that they are very flexible.

We know a couple who installed two head units in their 2,500-square-foot home. The house is across two levels, so they had a head unit serving each floor, working great for them. It provided plenty of heating and cooling throughout the year and suited their lifestyle very well.

However, during the Covid-19 pandemic, they found they were spending a lot more time in the bedroom at the far end of the house, which they had started to use as an office.

No problem, they thought, let’s just install another head unit in the office bedroom.

And that’s exactly what they did.

Their whole house is now extremely comfortable and well heated, with independent temperature control in each zone served by their three head units. Plus, their electricity bills are still meager, thanks to the incredible efficiency of their mini-split system.

So, don’t worry too much about how many head units you need for your system. Mini-splits are very flexible, and you can always add additional head units later if you decide you need them.

A homeowner sits at a desk against a wall below a mini-split's head unit near the ceiling

There’s minimal disruption during the installation process, unlike central air, where you’d need to add a bunch of extra ductwork, which can get messy, not to mention costly.

With a mini-split, all you must do is drill a 3″ hole in the wall, mount your head unit and connect it to the outdoor compressor with the refrigerant line sets and electric, and you’re done.

For more information about the differences between ductless mini-splits and central air, why not read our article on the subject?

Final Thoughts

Mini-split heat pumps are highly efficient heating and cooling devices that are straightforward to install in your home.

Each zone in the house is fitted with a head unit that blows hot or cold air into the living space to control the temperature of that zone.

A zone can be comprised of one or more rooms, and the temperature of each area is controlled independently, making them very versatile and great for when you want certain rooms to be kept warmer or cooler than others.

You don’t need a head unit in every room. Provided there is sufficient airflow between spaces, a single unit can control the temperature in multiple rooms within the same zone.

If you’re not sure how many air handlers you need, remember that mini-splits are very flexible, and you have the option to install additional units later if you find you need them.

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