The simple version
Think of a mini-split as a heat pump for one or more rooms. An outdoor compressor connects to indoor heads through a small line set (refrigerant, power, and condensate). No bulky duct trunks required, air is conditioned right at the room.
Interactive diagram
Ductless mini-split: zoned comfort, no ducts
Cooling mode: each head cools its own room; the outdoor unit rejects the heat.
Tap or click a numbered marker to see what each part does, or watch the animated flow to follow the cycle.
Single-zone vs. multi-zone
- Single-zone: one outdoor unit, one indoor head, perfect for a sunroom, garage shop, or problem bedroom.
- Multi-zone: one outdoor unit feeds several indoor heads, each with its own setpoint so family members aren't fighting over one thermostat.
Heating and cooling in the same box
Most ductless systems are heat pumps. In summer they reject heat outdoors; in winter a reversing valve flips the cycle and brings heat indoors, the same principle as central heat pumps, delivered room by room.
Where ductless shines in St. Louis
Humid summers make upstairs rooms sticky; cold snaps expose additions with little duct access. Ductless helps when plaster walls, finished basements, or historic layouts make new ductwork impractical. It can also complement a central system instead of replacing it, for example, cooling a bonus room that never gets enough supply air.
Repair vs. replace
Individual heads and outdoor units can often be repaired when young. Aging outdoor units, failing electronics, or undersized original installs may favor replacement. Use repair or replace as a framework, or get a free second opinion.
Compare before you decide
Not every home should go all-ductless. Weigh whole-home ducted cooling against zoned mini-splits in central AC vs. ductless, then explore Swiss Air ductless services when you're ready for a design visit.