What is a mini-split?

Meet the mini-split

Ducted heat pumps use your home’s existing ductwork (or new ducts if needed) to disperse heated or cooled air throughout your home.

Easier installation

But mini–split or “ductless” heat pumps are easier to install where there is no existing ductwork. Mini splits are usually mounted high on the wall, and each one serves one room or area of your home.

Offers more temperature control

Each unit can be set to a different temperature, so if one member of your household runs hot or cold, you can adjust your settings so everyone is comfortable!

More efficient

In addition to having more control over the temperature throughout your home, mini-splits tend to be more efficient than traditional air conditioners. And when turned to heating mode, they are between 2-4 times more efficient than a furnace, baseboard or a boiler. 

In this article we’ll explain how mini-splits work, look at their pros and cons, and answer frequently asked questions about heat pumps. 

How does a mini-split work?

In many ways, a mini-split functions much like a traditional air conditioning system. In cooling mode, it moves heat from inside your home to the outside air. The difference is where the cool air blows from. 

In a central-air system, the cool air comes out of a single “air handler” (basically a big fan in your attic or basement), then blows that cool air throughout all the ducts of your home. A mini-split, by comparison, can blow cool air from up to six separate air handlers, hence why they can offer customized zone-control.

There’s more to the process, involving expansion, compression, and evaporation. You can read about the whole process in our guide to how heat pumps work.

Heating and cooling “zones” 

When you install a mini-split, you have to choose how many “zones” or cooling/heating areas  you want throughout your home. You can install one indoor unit to cover just a single room or zone. Or you can install five or six indoor units and provide each area more temperature control.

Installing a single zone is ideal if you’re adding cooling or heating to a room that ducts are having trouble reaching, a new home addition, or an exterior space, like a garage or workshop. 

A multi-zone setup typically allows up to six indoor units to be connected to a single outdoor unit. Each indoor unit is connected to an outdoor unit by thin lines of refrigerant, power, and drainage.

Mounting your indoor unit 

Because of their thinner tubes and cable connections, the indoor units in a mini-split system can go more places than a traditional ducted vent. 

The most typical indoor unit you’ll see is a wall-mounted unit.  These are generally mounted about 6 inches from the ceiling in order to distribute cool air downwards, as the warmer air will rise.

Beyond wall-mounted, other indoor units can be:

• Floor-mounted: These are great for homes where windows, ceilings, or other room design prevents easy wall-mounting.

• Floor-standing: Best for walls with even less usable space.

• Ceiling cassette:or a more subtle look and better downward air spread.

• Ceiling suspended: Provides more airflow but makes more noise, too.

Benefits of mini-splits

A mini-split system gives you more control over exactly how you want your home cooled, heated, and dehumidified. Let’s walk through each benefit.

Individual control of each indoor unit

The indoor units in a mini-split system can be controlled with a remote control, a smart thermostat, or even  a mobile app. Rather than setting a single temperature to cover the whole range of your house, a mini-split lets you fine-tune for things like:

• Family members who disagree about the perfect temperature

• Rooms only occasionally used, whether at certain times of day (bedrooms, offices) or in general (guest rooms, attics)

• New additions or rooms in a home that don’t have ducts

• Individual rooms and areas with specific heating or cooling challenges (sunrooms, basements)

• Keeping pets comfortable in one room while you’re at work

Efficiency

Ducts are responsible for 20-30% air loss in a typical home, according to Energy Star. The cooling or heating coming from a mini-split system is generated at each unit so these losses can be avoided.

Another inherent advantage of mini-splits is allowing rooms or zones to be turned off entirely while providing heating or cooling to other areas.

Two major appliances for the price of one

In addition to cooling your home, mini-splits can also heat your home, which means when you install them you can avoid paying for a furnace or baseboards.

In heating mode, mini-splits use the same kind of no-duct thermal energy transfer to heat your home. And like all heat pumps, they can do it up to four times more efficiently than any other heating system. 

Higher-quality air

Ducted HVAC systems typically have one filter installed in a central, indoor location. Cleaning out the ducts typically requires professional service, which can put homeowners off the job (ask us how we know).

By comparison, each indoor unit in a mini-split setup has its own air filter that can be replaced with nothing more than a stepladder. 

Dehumidification

Whenever you turn on an air conditioner, you are also turning on a dehumidifier. With a mini-split this is the case, too. But mini-splits have one major advantage over traditional air conditioning systems in this regard.Imagine it’s a humid, but not entirely hot, day in October. You might not want to turn on your air conditioner. But, for both health and comfort reasons, you definitely don’t want to sit in a humid home. With a traditional air conditioning system you have two choices: Sit in humid misery, or turn the AC and bundle up.

If you have a mini-split, you can turn it on “reheat dehumidification mode,” which sounds more complex than it actually is. In this mode you can keep the temperature constant while removing humidity from the air. 

Downsides of mini-splits

Potentially higher upfront costs

Putting all-new ducts for a central air system into a home, especially an older home, is expensive.

But setting up a new mini-split system isn’t cheap, either. Even a single-zone system can cost an average of about $6,600. Multi-zone systems that cover an entire home may cost multiples of that.

Electrical requirements

Mini-splits often require electrical work, ranging from the simple (like running a 220 volt line to each indoor unit) to the complex (like upgrading your electrical panel). Some homeowners will have to upgrade their electrical service entirely from 100 Amps to 200 Amps. 

Mini-splits vs. central A/C

The case for mini-splits

As we’ve covered above, mini-splits have a lot of advantages over traditional air conditioners. Those advantages include: 

• More control over the temperature of individual rooms and spaces

• Higher efficiency and less energy loss through ducts

• The ability to heat your home up to 4 times more efficiently than a furnace or baseboard heater

• The ability to dehumidify your home without cooling it

• Cleaner air on average

The case for central AC

Mini-splits aren’t for everyone. Here are the main advantages of central air:

• Lower upfront cost if you want to cool your entire home 

• Less electrical work required

• Less obtrusive aesthetic 

Frequently asked questions

Do I need a mini-split for every room?

Not necessarily. A larger indoor unit can work for a “zone” of a home, not just a room. And if a room doesn’t need heating, cooling, or dehumidification, you can skip a mini-split in there.

That said, it’s more efficient to buy a properly-sized indoor unit for each room where you might want cooling, rather than buy larger units and hope they’ll cover multiple rooms.

Are mini-splits noisy?

A mini-split has two main components, an indoor unit and outdoor unit. Both will vary in their noise of operation, depending on the capacity of the unit and the temperatures they’re trying to reach. 

Manufacturers’ ratings generally show decibel levels of indoor units between 20-49, and outdoor units 45-60. Those are comparable, according to noise charts, to between a whisper and a library indoors, and a “quiet suburb” outdoors.

Can I install them myself?

Many brands sell DIY mini splits in single-zone and multi-zone configurations. You can probably walk into a big-box store and come home with most of the gear required to install mini-splits in your home. However, using an HVAC contractor provides many advantages. A typical DIY mini-split job involves electrical work, wall mounting, knowing exactly what’s inside your walls and drilling holes through them. Good contractors have experience with all of this and know the equipment they’re licensed to install. They’re familiar with your region, your style of home, and most importantly, they can help you set up your system to meet your heating and cooling needs. Most manufacturers offer up to 12 year warranties on equipment installed by licensed HVAC techs. 

That all might well be worth the dollars you’d save in a DIY installation. But if you’re technical and up for the challenge, give it a try! A typical DIY mini-split job involves electrical work, wall mounting, knowing exactly what’s inside your walls and drilling holes through them.

What are the electrical requirements for a mini-split?

Most high-efficiency mini-split systems require 208-230 Volt service. Some smaller units only call for 110-115 Volts, and could therefore rely on typical household power. Your HVAC contractor should know what your system demands, and whether your home’s current panel and service can provide it. If you’re at all uncertain, seek out a qualified and licensed electrician.

Do mini-split units come in colors other than white?

Most indoor and outdoor units only come in black and white, and you’ll have to do some hunting for black wall units. If you’re worried about a monochrome machine being an eyesore, remember that there are options for ceiling or floor mounting.

How can I camouflage or cover up a mini-split?

Beyond choosing a ceiling or floor-mounted mini-split unit, you may have to get creative to completely hide a wall unit.

LG’s Art Cool Gallery provides a frame in which you can place any image you choose, with the heating or cooling coming out of the sides of the wall unit. You and your contractor can also try some creative placement: in bookcases, inside old-fashioned radiator covers, under stairwells, and more. Anything that doesn’t block access to the air, the filters, or the equipment for service, and doesn’t put them too close to electronics is fair game.

Want to learn more about heat pumps and see if you qualify for federal, state, or local incentives to make the switch more affordable than ever? Check this out.