Ducted AC Units, Multi-Head Split Systems and Floor-Standing AC: Which Ductless or Ducted Setup Fits Your Home?

"Mini split" used to mean one wall-mounted head and one outdoor unit. Today the same inverter technology shows up as concealed ducted indoor units, ceiling cassettes, floor-standing consoles, and multi-head systems that run up to five rooms off a single condenser. The names pile up fast: ductable AC, ducted AC unit, multihead split system, floor standing AC, indoor air unit. They all describe parts of the same family, and the choice between them has more to do with your house than with the equipment.

The quick answer: A ducted (concealed-duct) mini split hides a slim indoor unit in a ceiling, attic, or closet and feeds a few short duct runs, so you get the quiet, variable-speed comfort of a mini split with nothing on the wall. A multi-head (multi-zone) split connects two to five indoor units of any style, wall, cassette, ducted, or floor console, to one outdoor unit, with independent temperature control in each room. Floor-standing consoles are the answer for rooms with no usable high wall space. Pick central ducted equipment when the house already has decent ductwork and you want one system for everything; pick multi-head when rooms have very different loads or schedules, or there are no ducts to work with.

First, what "inverter" means

Nearly every mini split, ducted or not, is an inverter system. The word refers to the compressor drive: instead of a single-speed compressor that is either fully on or fully off, an inverter converts incoming AC power to DC and then back to a variable-frequency output, so the compressor can run anywhere from a low idle to full capacity. The fan motors are variable-speed as well.

In practice the system ramps up to catch a room, then settles into a long, low-speed run that holds temperature steadily, removes more humidity, and uses less electricity than start-stop cycling. "Inverter AC" or "DC inverter" in a product name simply means variable-speed compressor; Goodman, ACiQ, and York central condensers are sold in inverter versions too.

Ducted mini split indoor units vs. conventional air handlers

A ducted mini split indoor unit (also called a concealed-duct, slim-duct, or ducted air handler) is a low-profile box, often under 10 inches tall, that mounts horizontally above a ceiling, in an attic, or in a soffit or closet. It has a supply opening and a return opening, you connect short duct runs to each, and the unit itself disappears. It uses the same refrigerant line set and the same outdoor unit as a wall-mounted head.

A conventional central air handler is a much larger vertical or horizontal cabinet that sits in a closet, basement, or attic and pushes air through a whole-house duct system. The key differences are blower strength and features:

The practical rule: a ducted mini split head is for a cluster of rooms with short duct runs, not for pushing air across an entire house. Connect one to 60 feet of undersized existing ductwork and airflow drops, the coil can ice, and the last room never gets comfortable. Our ducted air handler collection covers the mini split style; full-size cabinets live under air handlers.

Multi-head (multi-zone) split systems: one outdoor unit, two to five heads

A multi-head split puts a single, larger outdoor unit outside and runs separate refrigerant line sets to two, three, four, or five indoor units. Each indoor unit has its own thermostat or remote, so a bedroom can sit at 72°F while an unused office stays at 80°F. The indoor units can be mixed: a wall head in the living room, a ceiling cassette in the kitchen, a ducted unit serving three bedrooms, a floor console in the sunroom.

Three things to understand before you buy one:

• Heads can add up to more than the outdoor unit. Manufacturers allow the combined indoor capacity to exceed the outdoor rating, often by 30 percent or so, because not every room peaks at the same time. When they all call at once, the outdoor unit divides what it has, so size the head for a large open living area conservatively.
• All heads run in the same mode. A standard residential multi-zone system can heat or cool, but not both at the same moment.
• Minimum head size matters. The smallest indoor head in most lines is 9,000 BTU. A 10-by-12 bedroom needs far less, so a dedicated head there will be oversized, cycle more, and dehumidify less. A single ducted unit serving two or three small bedrooms is often the better design.

We sell multi-zone bundles sorted by zone count: 2-zone, 3-zone, 4-zone, and 5-zone systems, with ceiling cassettes and ducted heads available as alternatives to wall units in most of them.

Floor-standing and console units

A floor-standing (floor console) indoor unit mounts low on an exterior wall, roughly where a baseboard heater would go, and stands about two feet tall. Some models can be partially recessed into the wall. It uses the same line set and outdoor unit as any other head.

Floor consoles solve a placement problem: rooms with knee walls or sloped ceilings, rooms with windows or built-ins across the high wall, sunrooms with glass on every side, and finished basements where you want warm air introduced low. In heating mode a console is especially comfortable because heat is delivered at floor level rather than blown down from near the ceiling. The trade-offs are floor space along one wall and more visibility than a cassette or ducted unit.

Sizing each zone

Mini split heads come in fixed steps: 9,000, 12,000, 18,000, 24,000, and 36,000 BTU are the common sizes. Sizing a zone means estimating the room's heating and cooling load from square footage, ceiling height, insulation and window area, sun exposure, climate, and occupancy, then choosing the nearest head without going far over.

A per-square-foot rule gets you into the neighborhood, but a kitchen with a west-facing wall of glass and a shaded north bedroom of the same size can need very different heads. Use our mini split sizing calculator for a room-by-room estimate, then apply these adjustments:

• Round down, not up, when a room falls between sizes. Inverter heads have reserve, and an oversized head runs short cycles that leave the room clammy.
• In cold climates, size for the heating load if the system is your primary heat, and look for a low-ambient (hyper heat) outdoor unit rated to deliver capacity at 5°F or below.
• Choose the outdoor unit after the heads: its rated capacity should be at least 70 to 80 percent of the combined indoor total, and closer to 100 percent if the zones usually run together.

Line sets: lengths, limits, and pre-charged options

Every indoor head connects to the outdoor unit with a line set: two insulated copper tubes carrying liquid and suction refrigerant, plus a control cable and a condensate drain. The manufacturer publishes a maximum length per head, a maximum total for the system, and a maximum vertical separation. Many single-zone units allow 50 to 100 feet; multi-zone systems have per-head limits and a combined cap. Exceeding the factory charge length means adding refrigerant by weight, a licensed technician's job.

Line sets are also where MRCOOL's DIY series differs from everything else. MRCOOL DIY systems ship with pre-charged line sets fitted with quick-connect couplings: the refrigerant is already in the lines, the fittings seal when tightened, and no vacuum pump, gauges, or EPA 608 certification is needed. The sets come in fixed lengths (16, 25, 35, and 50 feet are typical), cannot be cut or shortened, and any extra length is looped gently rather than kinked. The DIY multi-zone condensers accept two to five heads the same way. Our MRCOOL DIY installation guide walks through the full process.

MRCOOL's Olympus series is the conventional-install counterpart: standard flare connections, line sets cut to length, charge set by a technician, and a wider selection of indoor units, including ducted and cassette heads for multi-zone layouts. The MRCOOL Universal series is different again. It is a central inverter heat pump condenser that pairs with a conventional air handler and whole-house ductwork, so it belongs in the central ducted column below rather than the mini split one.

Central ducted vs. multi-head: which wins where

Both approaches can heat and cool a whole house efficiently. The right one depends on what you are starting with.

Central ducted equipment usually wins when:

• The house already has a reasonably sized, sealed duct system reaching every room.
• You want a single filter, a whole-house media cabinet, or a humidifier on the return.
• You need electric or gas backup heat in the same cabinet.
• The home is large; one 4- or 5-ton inverter condenser with an air handler is typically less expensive than five separate heads.

A multi-head split usually wins when:

• There is no ductwork, or it is leaky, undersized, or routed through an unconditioned attic you would rather bypass.
• Rooms have very different schedules or loads: a home office used all day, bedrooms used only at night, a sunroom that bakes in summer.
• You are adding space (addition, converted garage, finished attic) that the existing system cannot reach.

Hybrids are common and sensible: a central system for the main floor plus a 2-zone mini split for a bonus room and attic office. Browse all indoor styles in our mini split collection.

FAQ

What is a "ductable" or ducted AC unit?

It is a mini split indoor unit built to connect to short duct runs instead of blowing directly into the room. It hides above a ceiling or in a closet and serves two to four nearby rooms through registers, using the same outdoor unit as any other mini split head.

How many indoor heads can one outdoor unit run?

Residential multi-zone condensers are sold for two, three, four, or five heads. The number of ports on the outdoor unit sets the maximum; a 5-zone condenser can run fewer heads if the combined capacity stays within the manufacturer's allowed range.

Can a multi-head system cool one room and heat another at the same time?

No. Standard residential multi-zone systems run every head in the same mode. Each head sets its own temperature and fan speed, but heating and cooling cannot happen simultaneously.

Is a floor-standing AC the same as a portable air conditioner?

No. A floor-standing (console) mini split is a permanently mounted indoor unit connected to an outdoor condenser. A portable AC is a single box on wheels that exhausts through a window. The console is far quieter and more efficient.

Do I need a contractor for a multi-zone mini split?

For conventional systems, yes: the lines must be flared or brazed, evacuated, and charged by weight, which requires EPA 608 certification. MRCOOL DIY systems with pre-charged quick-connect line sets are designed for homeowner installation, though a licensed electrician is still recommended for the dedicated circuit.

Shop at HVAC MORE. We stock single-zone and multi-zone mini splits, including MRCOOL DIY, Olympus, and Universal systems, with ducted and cassette indoor units and matching line sets. If you are weighing a central system against a multi-head layout, our system builder helps assemble a matched set, or contact us with your room list and we will help you size it.