Mini-Splits vs. Central Air Conditioning

By Kevin Purdy

Mini-Splits vs. Central Air Conditioning

What’s best for your home?

If you’re looking to install a cooling system for your home, you’ll likely come across two different options: ductless mini-splits and central air conditioning (central A/C).

Central air will be familiar to most: With this option, a big box outside your home moves hot air out of your home and cool air throughout ducts and vents.

Ductless mini-splits work in much the same way, but as the name suggests, they don’t require ducts. Instead that big box outside your home connects to anywhere between one and six separate air handlers. 

Which system you should pick for your home depends on a few factors, including: 

  • The size of your home and the rooms you want to cool
  •  Where you spend time throughout the day
  • Upfront and operating costs.

Let’s explore the two systems’ pros and cons and which option makes the most sense for you and your home.

What is a ductless mini-split?

As its name implies, a ductless mini-split system can cool rooms, or a whole home, without the need for ducts running all the way back to a central fan.

Like a traditional A/C system, a mini-split moves heat from inside your insulated home to the outside air, while moving cool air into your home. Unlike a traditional “central” A/C system, the cool air comes from each separate indoor air handler, rather than one central fan in your attic or basement.

Illustration of heat pump operation in cooling mode: indoor evaporator absorbs heat, refrigerant line takes heat outside, outdoor condenser pumps heat outside.

This split-up cooling system allows for zone control, and prevents the efficiency loss of moving air through long ducts. It also makes installing a mini-split system possible in homes where space is limited, or where ductwork would be intrusive and costly. Up to eight indoor units can be connected to a single outdoor unit.

However, unlike a traditional central air conditioning system, ductless mini-splits can also provide heat — and they can do it 3-4 times more efficiently than a furnace, boiler, or baseboard heat system. That means when you install mini-splits, you’re getting two major appliances for the price of one. 

To learn more, you can read our recent guide: What is a mini-split?. If you want to know more about the physics and mechanics of these systems, read our guide to how heat pumps work.

What is central air conditioning?

Central air conditioning does all of its work in a couple bigger units. An outdoor unit expels warm air, while an indoor air handler blows cool air throughout a home’s duct system. 

From there, it spreads to every room through vents. The whole system is controlled by a single thermostat, set to one temperature. The only real options for a homeowner are how wide you open each vent, and what kind of filter you put into the blower unit.

Benefits of ductless mini-splits

Having individual control of each cooling unit in your home gives you more control over temperatures, humidity, and your energy bills. Let’s walk through the benefits one by one.

Zone control of temperature and humidity

Each indoor unit in a mini-split system can be controlled by a remote control, an in-room thermostat, or sometimes a smartphone app. Zone control lets you adjust the temperature in each individual room for things like: :

  • People with different temperature preferences
  • Rooms that you don’t use during certain parts of the day like bedrooms, offices, playrooms, attics and basements.
  • New home additions or rooms without ducts
  • Rooms that get hotter or cooler than other parts of the house 
  • Pets left at home in a single room

Efficiency

Most homes lose 20-30% of their cooling capability in ducts, according to Energy Star. The cool air in a mini-split system comes out at each indoor unit, so it doesn’t have to make that energy-draining journey.

There are also inherent efficiencies in the zone control mentioned above. Most homes will have some temperature variation due to variations in sunlight, insulation, elevation, and construction. Allowing each unit to control how much to cool each room lowers energy use and saves you money on your utility bill each month.

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 or delay replacing your heating system in the future.

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. 

You can use a heat pump with a ducted system, but a mini-split system (which also uses heat pump technology) delivers this heat the most efficient way possible.

Easier, more flexible installation

If your home doesn’t have existing ducts, installing central AC can get very expensive.. It also requires opening up walls, ceilings, and floors to install ducts, vents, and air returns.

Mini-splits were built specifically to avoid ductwork, originally for Japanese homeowners. They work through thin pipes, rather than wide ducts. For homes without ductwork this often results in lower costs and complexity. 

Mini-split wall unit connected to outdoor unit: "Mini-splits don't require ducts"

Steady, constant temperature and dehumidification

Most new, high-SEER mini-split systems offer either dual-stage or variable-speed motors. When properly sized, mini-split systems can run at lower speeds for longer periods than less efficient central air. 

Rather than “kicking on” and blowing in gusts of cool air every so often, a mini-split unit can gradually pull moisture and heat from the air all day, keeping a room comfortable while keeping energy use low.

"Variable-speed vs. single-stage" chart showing wider variations for single-stage units than variable speed. "Variable-speed heat pumps prevent big swings in temperature and provide better comfort."

Downsides of mini-splits

Potentially higher upfront costs

If your home already has duct work, a low-SEER, single-stage AC system will cost you less money upfront than a mini-split system. 

Cheap, inefficient AC systems cost between $4,000-$8,000 according to Bob Vila.

Single-zone mini-splits cost $2,000-$6,000, while multi-zone systems that cover an entire home generally cost between $8,000-$12,000, according to homeowners and contractors we’ve talked to.

Electrical requirements

Mini-splits often require electrical work In some cases this may mean upgrading an electrical panel. In others it may mean upgrading from 100 amp to 200 amp service through your utility. 

Aesthetics of wall units

The typical mini-split configuration has each indoor unit hung on a wall. Wall units can be black or white. Many would consider them inoffensive. But some people won’t appreciate having anything hanging on their wall.

There are alternatives to wall units in a mini-split system, like floor-mounted, flush ceiling, and ceiling-suspended units. But both the equipment and labor costs go up with these options.

Individual filters instead of household filters

Each indoor unit in a mini-split system has its own smaller filter. This certainly reduces the spread of particles, but a ducted system moves the home’s air through a large filter, for which you can choose different filter levels (e.g. a heavy-duty MERV-15). 

That means if you have clean ducts, central AC will provide cleaner air than a mini-split system. 

Benefits of central air conditioning

Lower upfront costs (if you already have ducts)

If your home already has ducts, whether for heating or cooling, installing central air conditioning will cost less than a mini-split system.

As we mentioned above, a cheap, low-SEER air conditioner typically costs between $4,000 and $8,000. A whole home mini-split system, by comparison, typically costs between $8,000-$12,000.

Easier operation

Individual control of each zone or room can be great, but not if you don’t want, or need, that much control. Central air conditioning systems can generally be set to one temperature, and they’ll work until the thermostat (or, optionally, household sensors) reach it.

It may seem sub-optimal, but a single thermostat and temperature also means that you may be less likely to  accidentally leave one zone set quite low when nobody’s in it, or let it get too hot in a room where you turned off the system.

Filtration options

If pets, allergies, or other concerns require you to aggressively filter the air in your home, a traditional air handler in a ducted central air system gives you more options. These indoor units can accept larger filters with different HEPA filter levels.

Downsides of central air conditioning

Lack of zone control

Central air conditioning systems have two options: They can either be turned on or turned off. But as we mentioned above, there are a lot of situations where it comes in handy to turn on the AC or heat in just one room.

For example, maybe one room gets a lot of sun during the day. You might want to crank the AC in that room, but not turn the rest of your home into an ice box. 

Or maybe you leave your pet at home during the work day. It’d be a waste of money and energy to heat or cool the entire home if the pet just hangs out in one single room. 

Central AC systems, unlike ductless mini-splits, don’t solve either of these problems. 

Duct maintenance

Over time ducts get dirty, which can make the air you breathe less healthy. Cleaning them out can be a pain and is often too difficult for even the most handy homeowners. This means more maintenance and the headache of scheduling regular cleanings. 

Frequently asked questions

Do I have to choose between them? Can I use both?

If you already have ducts in your home, but they don’t cover an area of your home (or don’t provide enough air to it), you can augment your ducted system with a single-unit mini-split. 

Typically this involves installing an indoor unit a short distance from its outside counterpart, with short, narrow cables running between them. The indoor unit would be controlled separately from the main ducted system, and could be used only when needed.

Can I use a heat pump with either ducted or ductless systems?

Yes, a heat pump can provide the same kind of cooling, and super-efficient heating, with ducted or ductless systems. A heat pump is more efficient in a ductless system, but still provides heat that can save the average U.S. home hundreds of dollars per year in either setup.

Can I install a mini-split system myself?

MRCOOL, Pioneer, and other brands sell DIY mini splits in single-zone and multi-zone configurations. You can walk into a big-box store and come home with most of the gear required to install mini-splits in your home. But should you?

Using an HVAC contractor provides many inherent advantages to a DIY installation. Good contractors know the equipment they’re licensed to install. They’re familiar with your region, your style of home, and, of course, the type of work that needs to be done. And most importantly, 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. We’re heard stories of people saving thousands by doing a DIY install.

A good first step is looking up the manual of the model you’re considering and read it thoroughly. A typical DIY mini-split job involves electrical work, wall mounting, knowing exactly what’s inside your walls and drilling holes through them.

How often should I have a mini-split system serviced?

You can clean the filters on your indoor units yourself, at least monthly. But at least once a year you should have your ductless system professionally inspected.

All the things that make a ductless system quiet, clean, and efficient can be undone by leaks, wiring damage, clogged drains, or other issues that build up over time. A professional HVAC technician who knows your mini-split brand can ensure everything is running smoothly.

How often should I have the ducts on my central air system cleaned?

If your ducts have visible debris inside, if you smell a moldy or off odor coming from your vents, or if people in your home are experiencing atypical allergy-like symptoms, it’s time to have your ducts inspected and cleaned, right away.

Otherwise, HVAC providers and furnace manufacturers seem to average out to every two to three years for duct checks. Even if nothing seems particularly wrong with your ducts’ air, build-up in the ducts lowers efficiency, and breaks or leaks can be better caught with regular inspection.

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