Closeup on a mini-split air handler unit on the wall in the corner of a room

Mini-split heat pumps are a fantastic way to heat and cool your home. The beauty of mini-split systems is that they are incredibly versatile and can heat and cool your home perfectly throughout the year.

Not only are they highly efficient, but they also offer fantastic convenience and controllability. The ability to add additional zones easily to an existing installation later on is an excellent feature of these systems and shows just how flexible they are.

If you like a cool bedroom at night, but your kids can’t sleep unless they are nice and cozy, that’s no problem for a mini-split system. Simply adjust each zone accordingly and keep everyone comfortable and happy.

Each air handler can be set to a different temperature so that different zones are heated or cooled to just the right level.

But how many zones should you have running from a single outdoor unit?

We’ll be looking at this question in this article, so keep reading to find out.

Mini-splits are a great option for heating and cooling accessory dwelling units (ADUs). If you’re considering an ADU, why not read our article about them here?

How Many Zones Can a Mini-Split Heat Pump Service?

Each air handler on a mini-split heat pump system can heat and cool a different zone to the perfect temperature. The system can run up to eight zones off a single outdoor unit, which is enough for most homes, although homeowners can add more zones by installing an additional outdoor unit.

What Is a Mini-Split Heat Pump?

To appreciate how zones work in mini-split installations, we need to understand the critical components of these systems and how they operate together.

The outdoor unit is installed outside the building, on the wall, or on the ground. This unit houses the compressor and a coil that transfers heat between the refrigerant and the outside air.

The condenser unit of a mini-split next to a wall outside a home

The outdoor unit connects to one or more indoor units (also known as air handlers or head units) via copper piping called a line set.

The line set conveys the refrigerant around the system. It comprises two pipes, one that carries the dense liquid refrigerant from the condenser coil to the evaporator and one that transports the gaseous refrigerant back to the condenser from the evaporator.

The line set is usually encased in a conduit to keep things looking tidy and to protect them from damage. The conduit also contains electrical cables that provide power from the outdoor unit to each indoor unit and allow them to communicate with each other.

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

The condensate drain is often bundled with the line set and electrical cable inside the conduit.

What Is a Mini-Split Zone?

A zone in a mini-split system is simply part of a building that is controlled at the same temperature, independently of other zones in the building.

A zone is commonly a single room but can be several rooms within a home, for example, a large open area including a living room and dining area.

Each head unit inside a building can be controlled independently, which allows the temperature to be set individually. They are usually mounted on the wall or ceiling and can provide heating and cooling to one or more rooms, provided adequate circulation of air can be achieved.

Often a single head unit is required for each zone, but for large zones, homeowners might need two or more head units to provide the necessary heating and cooling. This requirement depends on the size of the zone, how freely the air can circulate, and the size of the air handlers.

Zone Requirements for Homes of Different Sizes

The decision about the number of zones is less about your home’s size and more about the layout and how you use the space.

For example, if you live in a narrow home with a linear layout, you might be able to heat and cool the whole building, or at least an entire floor, with a single head unit that directs airflow along your home.

On the other hand, if your home is less regular in shape and layout, you might need two or more zones to ensure you get conditioned air into all parts of your living space—this might mainly be the case if you have an add-on room, which needs to be heated and cooled separately.

An advantage of taking a zoned approach with your mini-split installation is that you can individually control the temperature in different rooms. For example, you might prefer your bedroom cooler than your living area. With a zoned mini-split, this is no problem.

A homeowners points a remote control at the air handler unit of her mini-split system

You could also save a lot of money on your electricity bills by only heating or cooling the part of your home that is actively being used. For example, if nobody is in a particular zone, there is no need to control the temperature, and the air handler in that room can be entirely dormant. 

So, the decision about the number of zones your home could require is more complex than simply how large your house is.

Nevertheless, it’s helpful to have some rules of thumb based on a typical setup.

Therefore, as a rough guide, we’ve put together the following table showing how many zones you might need for different sizes of homes:

Mini-Split Zone Counts for Various Floor Areas

Zone CountFloor Area
1500-1,000 sq ft
21,000-1,500 sq ft
31,200-1,800 sq ft
41,500-2,500 sq ft
51,800 – 2,800 sq ft
62,500 – 3,000 sq ft
72,800 – 3,500 sq ft
83,500 – 5,000 sq ft

Which Brands Offer Multi-Zone Systems?

Most mini-split manufacturers offer single-zone and multi-zone units.

The following brands offer both single and multi-zone systems:

  • Fujitsu
  • Mitsubishi
  • LG
  • Gree
  • Daikin

A single zone would simply be an outdoor unit paired with one indoor unit.

Homeowners can achieve multi-zone installations by adding up to eight head units to the outdoor unit. Adding a further outdoor unit is possible if you need more head units, which is a common practice when installing whole-house mini-split systems.

We’ve written an article about installing a mini-split system to heat an entire house, which shows how two outdoor units of 36,000 and 18,000 BTU were installed with six indoor units for complete heating. 

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

Adding extra outdoor units cuts down the distance between the outdoor and indoor units. It is sometimes necessary for larger houses because you would otherwise exceed the maximum distance between indoor and outdoor units.

It’s essential to remember that the outdoor unit must have a large enough capacity to work with all the head units connected to it.

Some outdoor units designed for multi-zone installations are as large as 60,000 BTU, but these are relatively rare, with the largest commonly used outdoor unit being around the 48,000 BTU mark.

If you need an outdoor unit as large as 48,000 BTU, you should consider installing two smaller units instead. This route is best discussed with your installer during the design stage, and we would always recommend getting professional advice when sizing your heat pump system.

If your unit is too small, it will struggle to provide the necessary heating or cooling, leaving you uncomfortable much of the time.

On the other hand, if you over-size your system, the mini-split will “short-cycle,” meaning it turns on and off repeatedly, which is inefficient and will increase your running costs and reduce the lifespan of your system.

Summary

Mini-splits are a highly efficient and flexible way to heat and cool your home. Multiple head units allow different rooms or zones to be heated and cooled to different temperatures.

This installation has the benefit of tailoring each room’s temperature to its occupants’ needs and allows unoccupied areas of the house to have the system switched off, which saves money.

Most brands make both single-zone and multi-zone systems, which can run up to eight zones off a single outdoor unit.

The outdoor unit must be large enough to run all the connected head units for multi-zone systems, although it can make sense to use two smaller outdoor units if there are many zones.

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