Ductless Mini-Split Installation in South Florida

Where mini-splits make sense in South Florida

A ductless mini-split pairs an outdoor unit with one or more wall-mounted indoor heads, connected by a small bundle of refrigerant line, wiring and drain. There is no ductwork, so no duct losses and no attic run to extend. They tend to fit best in places like these:

• Garages converted to living space, gyms or workshops
• Room additions the existing ducts never reached
• Florida rooms and enclosed or converted lanais
• Home offices and server or equipment rooms that need steady cooling
• Older homes without ducts
• Casitas, guest suites and in-law suites

Adding a room to an existing central system is a common trap. The system was sized for the original house, so the new room can leave every room a little short, and the ducts may not reach it anyway. A separate mini-split gives the new space its own capacity and thermostat. If you are instead replacing a whole ducted system, start with our [AC installation and replacement guide](/ac-installation-replacement/).

Sizing each zone

Size each zone on its own load, not on the window unit it replaces. A room's load depends on square footage, glass and sun exposure, insulation, ceiling height and what goes on in it. Garages, lanais and rooms with west-facing glass often need more capacity per square foot than an interior bedroom, and a room full of electronics adds heat. Indoor heads come in steps such as 9,000, 12,000, 18,000 and 24,000 BTU per hour.

Inverter-driven models can turn down to match a light load, so they tolerate small errors better than fixed-speed units. A badly oversized head in a small room still runs at its minimum output and does a poor job on humidity. Ask for a room-by-room Manual J calculation.

Condensate, line sets and wall penetrations

A mini-split pulls a lot of water out of humid air, and it has to go somewhere. The indoor head drains by gravity through a line that must slope continuously downward to an approved discharge point, usually outside the wall behind the unit. When that slope is not possible, a condensate pump is needed, with a safety switch that shuts the system off if the pump fails.

The line set (insulated refrigerant lines, wiring and drain) passes through a hole in the wall, commonly about three inches across, cored through block, stucco or frame. That opening must be sealed against water, insects and air, and the exterior run covered to protect the lines from sun and weather.

Permits

A mini-split installation is mechanical permit work, and a new circuit and disconnect typically bring an electrical permit. Outdoor units and brackets must be anchored for wind loads, and the rules are stricter in Miami-Dade and Broward because both are in the High-Velocity Hurricane Zone. In a condo or an HOA community, get approval before any exterior unit or wall penetration, since many associations regulate where condensers can go. A licensed contractor pulls the permits and schedules the inspection.

Common mistakes to avoid

• Undersized or overlong line sets, which starve the system and cut efficiency
• Skipping the nitrogen pressure test and vacuum, which leaves leaks and moisture in the system
• No condensate pump where gravity drainage will not work
• Mounting a head over a bed or sofa, where cold air and any drip land on people
• Placing a head too close to the ceiling or behind furniture and curtains
• Sizing from the old window unit instead of the room
• Putting the outdoor unit under a roof drip or without clearance for airflow and service

Mini-splits need upkeep too. In a humid climate the washable filters in each head typically need cleaning every month or two, and the indoor coil, blower wheel and drain line need periodic professional cleaning because damp surfaces can grow mold. Our [AC maintenance and tune-up](/ac-maintenance/) page covers what a visit includes.