Most Florida homes with existing ductwork are better served by a central system. Mini-splits earn their place where there are no ducts, or where running ducts would be awkward: an addition, a converted garage, a bonus room, a workshop. The mistake is using one where the other belongs.
The short version
- Choose central air if the house already has ductwork in reasonable condition and you want to cool and dry the whole home with one system.
- Choose a mini-split for a single room or zone with no ducts, or a space the central system can't reach well.
- Don't try to replace a whole-house ducted system with one mini-split. A single-zone unit cools the room it is in, not the rooms around it.
How each one works
Central air is a condenser outside and an air handler inside, usually in a closet, attic or garage. The air handler pushes cooled air through ductwork to every room and pulls it back through a return. One system, one thermostat, the whole house.
A ductless mini-split is a condenser outside and an indoor head mounted high on a wall, joined by a refrigerant line set through a small hole in the wall. There are no ducts. Each head cools the space it sits in. Our Everwell MKTH-17 mini-split is single-zone: one outdoor unit, one indoor head. It is a heat pump, so it heats as well as cools. If you are choosing between a heat pump and a straight air conditioner for a central system, see heat pump or AC in Florida.
When a mini-split makes sense
- No ductwork. An older home, a block building or an outbuilding that has never had central air.
- Additions and conversions. A new room, an enclosed porch or a converted garage that the existing system was never sized for.
- Rooms over a garage or next to unconditioned space. ENERGY STAR lists these as a common use, because ducts running through hot spaces lose a lot of their cooling.
- A single problem room. A home office or bedroom that is always hotter than the rest of the house.
- Workshops and sheds. Where you want cooling only when you are in there.
When central air makes sense
- Existing ducts in reasonable condition. Replacing a central system with another central system is the simplest, lowest-disruption job.
- Whole-house cooling. Every room conditioned and dried from one system.
- Hidden equipment. No heads on the walls. Just supply grilles and a return.
- Filtration in one place. One filter at the return, cleaning the air for the whole house.
- Rebates. FPL's AC rebate excludes single-zone mini-splits, and TECO's covers ducted systems only. Details on our HVAC rebates page.
Humidity: the Florida question
In Florida, removing moisture matters as much as lowering the temperature. Both systems dry the air the same way: warm, damp air passes over a cold coil, water condenses out and drains away. The difference is where that happens and for how long.
Central air dries the whole house, because all the air passes through one coil. It works best when the system is sized correctly. An oversized system cools the house quickly and shuts off before it has removed much moisture, which is why some homes feel cold and clammy at the same time.
A mini-split dries the room it is in. The MKTH-17 is inverter-driven, so it can slow down rather than switch on and off, and long runs at low speed are good for moisture removal. But it does nothing for a closed-off bedroom down the hall.
Garages are a special case. Most garages leak a lot of outside air through the door and walls. A mini-split in an unsealed garage will run hard and still struggle with humidity. Seal and insulate the space first, or expect it to feel warmer than the house.
Either system needs a proper condensate drain. A mini-split head drains through a line run outside or to a pump. A central air handler drains through a line that should have a float switch to shut the system off if the line clogs. In Florida, drain lines clog. Plan for it.
Efficiency
Our mini-split rates higher than our central systems. The Everwell MKTH-17 rates 17 to 20 SEER2 depending on size. The central systems we carry rate from 14.3 SEER2 up to 17 SEER2, depending on the pair and the tonnage.
Ducts are part of the reason. ENERGY STAR notes that losses from ductwork can account for more than 30% of a home's energy use for heating and cooling, especially when ducts run through a hot attic. A mini-split has no ducts to lose energy from.
That doesn't make a mini-split the right answer for a whole house. If your ducts are sound and sealed, a correctly sized central system is efficient and far simpler than putting a head in every room.
Cost: per room vs whole home
This is where the comparison usually goes wrong.
For one room, a mini-split is usually the cheaper route. One small outdoor unit, one head, a line set and a wall bracket or pad. No ductwork to build. Compare that with extending ducts from the main system, which may also be too small to take the extra load.
For a whole house, central air is usually the cheaper route. One condenser and one air handler serve every room. Replicating that with single-zone mini-splits means one outdoor unit and one head per room or zone, each with its own line set, drain and electrical circuit. The equipment and installation costs multiply.
Our complete central systems are listed with prices by size in central air systems. For a full breakdown of a 3-ton system, see how much a 3-ton AC costs.
Maintenance
Mini-splits: the filters sit inside the indoor head and are washable. In a humid climate with heavy use, they need cleaning often. Follow the interval in the user manual. Over time the head's coil and blower wheel can collect dust and growth and need a professional clean. Keep plants and debris clear of the outdoor unit.
Central air: one filter at the return, changed on schedule. Keep the condensate drain clear, keep the outdoor coil clean, and have the system checked periodically.
Neither is maintenance-free. A mini-split has more small things to keep up with, especially if you have several of them.
Hurricanes, wall brackets and outdoor units
Florida's building code expects outdoor mechanical equipment to be secured against wind. In practice that means the condenser is anchored to its pad, stand or bracket in a way your local building department accepts. Requirements and inspections vary by jurisdiction, so let your licensed installer handle it.
- Wall brackets lift a mini-split condenser off the ground, clear of debris and standing water. That helps in flood-prone yards. But the wall has to carry the unit's weight. Our mini-split wall bracket fits 9,000 to 36,000 BTU outdoor units, and your installer should check the wall before mounting.
- Ground pads are the usual choice for central condensers and work for mini-splits too, with proper tie-downs.
- Wind load documentation is often asked for at permit. The MKTH-17 product page includes a wind load certification document. For a central condenser, your installer will know what your building department asks for.
Before a storm, turn the system off at the breaker and the outdoor disconnect. Don't run it on generator power unless the generator is sized for it.
Warranty differs too
Check this before you decide. With valid registration, the Everwell MKTH-17 mini-split carries 5 years on the compressor, 2 years on parts and 1 year on the coil. Everwell's CAC-15 central systems carry 10 years on the compressor, 10 years on parts and 5 years on the coil. Trane and RunTru central systems carry 5 years on parts as standard, extending to 10 years on most components when registered within 60 days. All of them require a licensed installer. The Trane, RunTru and Everwell CAC-15 warranties don't cover labour, and the MKTH-17 warranty supplies covered parts with shipping paid by the customer. Full terms are on each product page.
When neither of our options fits
If you want to cool three or four rooms without ducts from a single outdoor unit, you need a multi-zone mini-split. We don't carry those right now. If your ducts are badly damaged, leaking or too small, fixing them may matter more than which equipment you buy. A good installer will tell you.
Questions?
Tell us the space, the square footage and whether there are ducts, and we'll tell you which way we would go.
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