Mini-split and ductless AC in Miami, FL

A mini-split is a small outdoor condenser and one or more indoor wall units joined by a refrigerant line through a three-inch hole, with no ducts. In Miami-Dade that solves a specific list of problems: the room the central system never reached, the garage or Florida room that was enclosed without permits for ducts, the 1950s block house in Hialeah or Westchester that still runs on window units, and the condo where the building will not allow a new air handler closet. It is also what replaces a wall unit in a rental without rebuilding the room.

When you call, say which room or rooms, their size, and whether there is an outside wall. The contractor looks first and quotes it in writing.

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Where a mini-split is the right answer

• A single room or an addition where extending the ducts would mean opening ceilings, or where the existing system is already at its limit.
• A garage conversion, Florida room, or enclosed patio: the space was never part of the duct design, and the central system cannot add it without starving the rest of the house.
• A house with no ducts at all, still on window units. Two to four indoor heads on one outdoor unit can cool the whole house without an attic full of duct.
• A condo or townhouse where the association allows a small condenser on a balcony or roof but not new ductwork.
• A home office, an in-law suite, or a bedroom that has to be colder than the rest of the house without freezing everyone else.

Where it is the wrong answer

Replacing a whole central system with mini-splits in a house that has good ducts costs more, puts a wall unit in every room, and gives up the filtration and humidity control a central air handler provides. A ductless head cools the room it is in; it does not condition the hallway, the closets, or the bathrooms, and in Miami humidity that shows up as musty spaces. A contractor who suggests it for a 2,000-square-foot house with working ducts should have a specific reason.

What a proper installation includes

• A permit from your city or Miami-Dade RER, an electrical permit if a new circuit is run, and the inspections. Mini-splits are permitted work in Florida like any other AC.
• Sizing by the room, not by the box on the shelf. An oversized head short-cycles and leaves the room clammy; the contractor should ask about the room’s size, sun exposure, and insulation.
• A condenser pad or wall bracket rated for wind, per the Florida Building Code high-velocity hurricane zone rules that apply in Miami-Dade, and a line-set cover on the outside wall rather than bare insulation that the sun destroys in a year.
• A condensate drain that actually drains, by gravity or a pump, and not onto the neighbor’s balcony. Most condo complaints about mini-splits are about the drip.
• Refrigerant charge set by weight and verified by pressure, with the line set vacuumed before charging. The system is only as good as the vacuum.
• A written warranty from the contractor on labor, separate from the manufacturer’s parts and compressor warranty, and confirmation that the installer is authorized for the brand, which some manufacturers require for the warranty to hold.

Repair and cleaning

The wall units collect dust and mold in the blower wheel and coil faster than a central system does, and the usual complaints are a smell when it starts, water dripping from the front, or one head that cools while the other does not. Cleaning a head properly means opening it and washing the wheel and coil, not spraying the filters; done yearly in Miami. Repairs are the same as any AC: sensors, boards, the condensate pump, refrigerant leaks at the flare fittings. Parts for the major brands are stocked locally; for the no-name units sold online they often are not, which is worth knowing before you buy one.

What drives the price

We do not quote. The contractor’s written quote reflects the number of indoor heads, the outdoor unit’s capacity and efficiency, the length and routing of the line set, whether a new electrical circuit is needed, the wall or roof mounting, the permit fees, and the brand. Single-zone systems for one room are the low end; multi-zone systems for a whole house are priced against a central replacement and should be compared to one.