The head unit of a mini-split near the ceiling in a common areas of a home above two doors

Mini-split heat pump systems have been popular in other parts of the world for decades. More recently, the US market is catching up to take advantage of these inverter-driven compressor units that can run at variable speeds with incredible efficiency.

They are an excellent choice for renovations and are often installed to provide heating and cooling for add-on rooms, such as attics and converted garages. 

However, the question many homeowners ask is whether mini-splits work in homes with many rooms. Those looking for an alternative to traditional central air systems need to know whether mini-splits can provide HVAC duties for the whole house.

So, can they?

By the time you’ve finished reading this article, you’ll have a solid understanding of how mini-splits function and if they can effectively heat and cool the whole house.

Do Mini-Splits Work For an Entire House? (Many Rooms)

Ductless mini-splits can provide HVAC for an entire house. Mini-splits are more efficient than central AC because air is dispersed via refrigerant lines instead of ducts. Further increasing the efficiency of mini-splits, zones can be created to maintain different temperatures in various parts of the home.

What Is a Ductless Mini-Split?

A ductless mini-split is an HVAC system that is permanently installed in your home. They are comprised of two main parts, the indoor air handler (also called the evaporator or head unit) and the outdoor component, which houses the compressor that pumps refrigerant around the system.

The outdoor compressor component of a ductless mini-split

Benefits of a Mini-Split System

Mini-splits offer several benefits over traditional central air heating and cooling systems.

They include:

  • High efficiency compared to central air (around 30% of the heating or cooling energy is lost in ductwork due to leaks and other issues).
  • Quiet operation—say goodbye to your whistling, popping, buzzing ductwork.
  • Homeowners can create zones to maintain different temperatures in different parts of the home (e.g., more comfortable bedrooms).
  • Lower running costs due to their super high efficiency
  • Ideal for providing extra heat for an add-on room, attic conversion, or insulated garage

Can One Mini-Split Cool Multiple Rooms?

Ductless mini-splits are capable of heating and cooling multiple rooms. A single outdoor heat pump unit can be connected to numerous indoor head units. Each unit would be responsible for cooling a single room, and, as a general rule, it is possible to hook up to four head units to a single outdoor unit.

This arrangement is very flexible, and you can connect additional head units later if required.

For example, further down the line, you might decide to convert an attic space in your home, and at that point, you might want to add another head unit to your existing mini-split. Again, this is possible with some units, provided you don’t exceed their total capacity.

A ductless mini-split installed below the roofline ceiling on the second story of a home

If you are considering an attic conversion, you should make sure that you insulate it properly. Unfortunately, this is sometimes overlooked and can prove to be a costly mistake.

To avoid this mistake and ensure you use the correct type of insulation, please read our article on the subject.

Do You Have to Put a Mini-Split in Every Room?

A mini-split air handler isn’t required in every room. However, provided you can ensure airflow from the head unit to the living areas you want to heat or cool, you can include more than one room in a “zone” served by a single evaporator.

Dividing your home into zones for heating and cooling provides a fantastic way to ensure the comfort of every family member while running your mini-split most efficiently.

For example, you might prefer a cooler bedroom, but other family members like a bit more warmth while they sleep. Or perhaps you want your living room kept cozy but your home office a little cooler to keep you alert and focused.

This is no problem for a mini-split heat pump system. Simply design your system to include various zones that cater to the different needs of separate parts of your home. This way, you can control each zone independently and ensure the temperature is perfect everywhere.

Customizability is one of the significant benefits of a mini-split compared to central air, which is much less controllable and harder to run in a way that maintains different parts of the house at different temperatures.

With the right choice of unit, you can split your home into up to eight zones on a single outdoor unit. That’s enough for most homes, even with the most diverse comfort requirements.

How Far Can an Evaporator Be From the Condenser?

If you have a large house, possibly spread over several floors, you might have concerns about the distance between your outdoor unit and the furthest head units.

The efficiency of your system would reduce if the distance were considerable because the refrigerant would have further to travel. This would increase the energy required to pump the refrigerant around the system due to head losses caused by friction in the pipes.

An illustrated diagram of how a ductless mini-split system functions

It would also result in more heat transfer between the refrigerant in the lines and the ambient air, causing the refrigerant to lose heat when in heating mode and gain it in cooling mode.

However, the refrigerant lines are well insulated, which mitigates this heat transfer effect, and the compressor is designed to be able to pump refrigerant quite long distances.

Typically, the distance between the outdoor unit and head units can be up to 66-98 feet, depending on the make and model of the system. That’s quite a distance and ample for most houses.

If you need a longer distance than that, or if you exceed the number of head units on a single outdoor unit, you can always add another outdoor unit on the other side of the house to get the job done.

How Many Square Feet Can a Mini-Split Heat or Cool?

Mini-split heat pumps are available in various sizes to suit any home.

Rated in Btu per hour, most manufacturers provide a range of differently sized units to allow you to pick the appropriate size for your home. Btu (British Thermal Units) is defined as the amount of heat energy required to raise the temperature of a single pound of water by one degree Fahrenheit.

The number of Btu that your unit needs to deliver depends not only on the square footage of your home but also on factors like the typical outdoor air temperature, the indoor temperature you would like to maintain, and how well insulated your house is.

That’s why it is so important to consult a professional installer before deciding on the size of the system you will need. A professional will be able to advise you on the correct sizing, having accounted for all the relevant factors, and after performing the necessary calculations.

It’s not something you want to leave to chance, so get it done correctly.

The table below provides some ballpark with Btu figures for specific floor areas to give you a rough estimate. This is just to give you an idea—make sure you get proper advice before taking things further.

Approximate Size of Mini-Split Heat Pump Required to Heat Different Floor Areas*

Size of Unit (Btu/h)Floor Area to be Heated or Cooled (ft2)
6,000150-300
9,000300-500
12,000400-650
15,000500-800
18,000600-1000
24,000800-1,300
30,0001,000-1,650
36,0001,200-2,000
42,0001,400-2,300
48,0001,600-2,650
56,0001,850-3,100

*These are approximate figures, provided as a guide only. Do not rely on these figures for sizing your mini-split. You must get professional advice to obtain accurate sizes for your home.

Ductless Mini-Split Example

Let’s look at a real-life example of a mini-split installation that heats and cools multiple rooms in the same house.

Paul The Plumber has shared an excellent video on YouTube about a ductless installation he completed recently:

Courtesy of Paul the Plumber

Mini-Split Model and Size

Paul describes a new Daikin AURORA Series mini-split installation in New England. The primary unit is an extended heat unit, which works at 100% efficiency down to 5۠°F, and is perfect for the colder weather often experienced there.

The system has a total of six indoor air handler units and two outdoor units, which in combination provide heating and cooling for the entire house.

The larger unit with four heads attached is a 36,000 Btu unit and is very quiet. It can hardly be heard on the video even though it is running right next to Paul while he is recording.

The second outdoor unit, which runs the remaining two of the six head units, is an 18,000 Btu unit. It’s the same model as the larger unit but just half the size.

Mini-Split Installation

The installation itself is very discreet, with a white “slim duct” covering that conceals the refrigerant lines and electrical from view in a plastic sheath that matches the color of the house walls.

There are head units mounted on the wall in the kitchen and each of the bedrooms, with one of the bedroom units being a floor unit due to the sloping attic walls, which are unsuitable for a wall-mounted unit.

The units are installed unobtrusively, so they are not visible as you walk into each room. Usually, in a quiet corner, out of the way.

A technician adjusts the indoor component of a mini-split

The remote control for each unit is stored on the wall in a purpose-made holder and allows you to program them individually to control the temperature of the room (or zone) that it serves.

The bathrooms have no head units installed. Instead, the system is designed to push as much airflow as possible to bathrooms from the other head units.

The house will soon be getting solar panels installed on the roof, providing power for the mini-split. This addition will make the system highly efficient and save the owners a lot of money in running costs.

Wrapping Up

Mini-splits have been popular in other parts of the world for a long time but have only recently caught on in the US.

They are a very efficient way to heat and cool your home and are proving popular for add-on rooms and areas in houses that need a little extra heat or cooling without the hassle of installing new ductwork.

As well as being an easy way to install heating for hard-to-reach living areas like attic conversions, mini-splits are an excellent HVAC option for your whole house.

Models are available in various sizes and can provide enough heating and cooling to run up to four air handlers. If you need more evaporators than that, you can easily add another compressor to power additional head units and extend the range and capability of the system.

Mini-splits can maintain the temperature in different zones independently. This feature is not only a nice to have when members of the household have distinct temperature preferences but also allows you to turn off units in specific rooms when not in use.

This helps to reduce running costs further when compared to central air systems.

If you are interested in installing your own mini-split system and would like to know how much these systems typically cost, why not read our article on the subject?

We break down the costs according to how many zones you need and your floor area. We also give you an idea of how much you could expect to save on your utility bills once the system is installed.

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