If your house still runs on window units, summer means hauling them out, cleaning them, and listening to a different rattle in every room while the electric bill climbs. Converting to central air in 2026 solves the noise, the uneven cooling, and the bill all at once, but the switch involves real ductwork decisions most homeowners never think through until a contractor is standing in their attic.
- Converting window units to central air starts with a load calculation, not added-up window unit BTUs.
- Carrier, Ruud, and Daikin heat pumps at 15.2 SEER2 or higher are the standard pick for South Florida conversions in 2026.
- Central air needs real ductwork, not just a bigger condenser. Attic space and chase routing decide the cost.
- A two-zone system solves the two-story window unit problem where upstairs bedrooms never cooled evenly.
- Skip any contractor who skips the permit. Palm Beach, Martin, and St. Lucie counties all inspect new duct runs.
Why this matters
A lot of South Florida homes built between the 1960s and 1980s never got central air because retrofitting ductwork into a house with no attic access used to be expensive and disruptive. Window units were the workaround, and in plenty of houses they've stayed the workaround for decades.
That's changed. Flexible duct routing, smaller air handlers, and better insulation options make sizing a system correctly realistic for homes that would have been poor conversion candidates 20 years ago. Running four or five window units all summer also costs more than one properly sized central air system, and none of them control humidity the way a whole-home system does. In a climate where indoor humidity above 60% invites mold on drywall and baseboards, that gap matters more here than almost anywhere else in the country.
Who this is for
This guide is for homeowners in older South Florida houses, the kind built decades ago in West Palm Beach, Lake Worth Beach, and along the Treasure Coast, where window units were the original cooling answer and never got replaced. If you're managing three or more window units, dealing with rooms that never cool evenly, or getting ready to sell a home that still shows window units in the listing photos, this is the decision you're weighing.
What to look for when converting window units to central air
Ductwork feasibility
Central air needs somewhere to put the ducts, whether that's an attic, a dropped ceiling, or a chase built into a closet. Homes with usable attic space are the easiest conversions. Homes without one need a real walk-through before anyone quotes a number, because running ducts through finished walls costs more and takes longer than routing through open attic trusses.
Correct system sizing
Don't size the new system by adding up your window units' BTU ratings. A load calculation looks at square footage, insulation, window orientation, and ceiling height, none of which have anything to do with how many window units you happened to buy over the years. Get this step wrong and the system short cycles, runs up indoor humidity, and wears out early.
Electrical capacity
A central air condenser and air handler pull more amperage than a row of window unit outlets ever did. The panel needs to support a dedicated circuit for the outdoor unit, and older homes running 100-amp panels sometimes need an upgrade before installation day.
Permitting and inspection
Palm Beach, Martin, and St. Lucie counties each handle HVAC permits a little differently, and a new duct system almost always triggers an inspection that a simple equipment swap wouldn't. Skipping this step is the fastest way to end up with a system that can't be documented when you sell the house.
Coastal equipment protection
Salt air corrodes unprotected outdoor coils fast, especially within a mile or two of the water. If you're converting a home in Delray Beach or Boca Raton, ask what coil coating or cabinet protection comes standard before comparing anything else.
Top conversion approaches
The straightforward pick: a new duct run through open attic space. This works when your home already has attic access and trusses that can carry a trunk line. Attic temperatures in South Florida regularly hit 130 to 140 degrees in summer, so insulation and duct sealing matter as much as the metal itself. Recommended for homes with open, unfinished attic space.
The retrofit pick: routing through an existing closet chase. For homes without attic access, a closet or hallway chase can carry a duct trunk to a centrally located air handler. It costs more in labor than an attic run but avoids tearing into finished ceilings. Consider this if your home already has a chase framed in from a prior addition or renovation.
The equipment pick: a matched Carrier, Ruud, or Daikin system at 15.2 SEER2 or higher. As a Carrier Authorized Dealer, Ruud Pro Partner, and Daikin Comfort Pro, A.R. Williams Air Conditioning installs matched systems, meaning the condenser, air handler, and coil are built to work together instead of whatever mismatched pieces happen to be on the truck. Compare the options on the best AC brands for South Florida homes page before you decide. Recommended, matched systems hold their rated efficiency longer than mixed components.
The zoned pick: two independent zones for a two-story house. If window units are already cooling upstairs and downstairs separately, a single-zone central air system will recreate the same uneven comfort with one thermostat instead of two. A two-zone setup with separate dampers keeps upstairs bedrooms from running noticeably warmer than the living space below. Consider this for any two-story home converting from four or more window units.
What to avoid
Adding window unit BTUs together to size the new system. It looks like simple math, but a load calculation and a BTU total rarely land on the same number, and an oversized system short cycles instead of running the long, steady cycles that actually pull humidity out of the air.
A contractor who skips the permit application. A duct system installed without inspection can become a real problem at closing when a buyer's inspector can't find the paperwork.
An unprotected coil chosen without asking about coastal protection. A coil that starts corroding within a couple of cooling seasons ends up costing more in replacement than the protected version would have upfront.
Verdict comparison
| Approach | Ductwork needed | Best for | Verdict |
|---|---|---|---|
| Attic duct run | Full new trunk and branches | Homes with open attic access | Recommended |
| Closet chase retrofit | Partial run through existing chase | Homes with no attic access | Consider |
| Matched Carrier, Ruud, or Daikin system | Depends on duct approach above | Homeowners prioritizing long-term efficiency | Recommended |
| Two-zone system | Full run plus zoning dampers | Two-story homes with uneven cooling | Consider |
Ready to plan your conversion?
Get a walk-through and a flat-rate quote before any work starts.
FAQ
How much does it cost to convert window units to central air?
Cost depends on existing ductwork, home size, and equipment tier, so there’s no single fixed number. A walk-through assessment is the only way to get an accurate, flat-rate quote for your specific home.
Is central air better than window units in South Florida?
Yes, for most homes running three or more units. Central air controls humidity more evenly, runs quieter, and puts the whole house under one thermostat instead of several mismatched settings.
How long does converting window units to central air take?
Timeline depends on how much new ductwork the home needs. A home with open attic access moves faster than one requiring chase construction or electrical panel upgrades.
Can you add ductwork to a home that never had central air?
In most cases, yes. Feasibility depends on attic access, ceiling height, and whether a chase can be routed through closets or hallways without major demolition.
Do window units use more electricity than central air?
Running several window units through a South Florida summer generally costs more than one properly sized, matched central air system rated at 15.2 SEER2 or higher.
What size central air system do I need if I currently have window units?
Size comes from a load calculation based on square footage, insulation, and window exposure, not from adding up your window units’ BTU ratings.
Can I use my existing window unit outlets for a new central air system?
No. A central air condenser needs a dedicated circuit sized for its own amperage draw, which standard window unit outlets aren’t built to handle.
One last thing
Most homeowners focus entirely on the new equipment and forget about the old openings. Once the window units come out, sealing those wall cutouts stops years of humid outside air and insects from working their way into the wall cavity, and it does almost as much for comfort as the new system itself.
A.R. Williams Air Conditioning walks homeowners through this exact evaluation, ductwork feasibility, sizing, permitting, and equipment, before quoting anything. If you're weighing a conversion for 2026, get the walk-through first and the number second.
Related guides
- Duct repair and sealing for South Florida homes
- Zoning systems for large South Florida homes
- How to verify your AC contractor is licensed in Florida
