Central cooling conditions air in one place and distributes it through ducts. A ductless system moves refrigerant to each room and conditions the air there. That single difference produces every other distinction between the two projects.
What Each One Needs From the Building
| Requirement | Central system | Ductless system |
|---|---|---|
| Air distribution | Duct trunk, branches, supply registers and adequate return | None; each head serves its own room |
| Penetrations | One line set route to the indoor coil | One wall penetration per indoor head |
| Indoor equipment space | Coil cabinet on the furnace or air handler | Wall, ceiling or floor unit visible in each room |
| Condensate | Single drain at the coil, sometimes with a pump | Drain from every head, gravity or pumped |
| Filtration | Central filter serving the whole house | Washable pre-filter in each head |
| Zoning | Added with dampers and a zone panel | Inherent; each head has its own setpoint |
Where Ductless Is Clearly the Better Fit
Rooms with no duct path win the argument outright. Attic conversions, rear additions, enclosed porches, garages and workshops fall into that group, and so does any room where a duct run would cost a closet. Ductless also fits houses with radiators or baseboard heat, where no forced-air distribution exists at all and building one would be the largest part of the project.
Where Central Still Wins
A house with a sound duct system and adequate return capacity is usually served better by central equipment. One filter, one machine to maintain and no visible indoor units in living spaces are real advantages. Whole-house humidity control is also easier to manage from a single coil, and the equipment sits out of sight in a basement or attic rather than on a bedroom wall.
The Comparison That Actually Decides It
- How many rooms need conditioning, and whether they sit together or scattered across the building.
- Existence of a duct route that does not consume finished space.
- What the heating system is, since a forced-air furnace already provides the distribution a central coil needs.
- Tolerance for visible indoor equipment.
- Value placed on independent room-by-room setpoints, which ductless equipment provides without any additional dampers, panels or control wiring.
Mixed Systems Are Common and Sensible
Plenty of Chicago houses end up with both. A central system handles the main floors through existing ducts while one or two heads cover the attic bedroom and the addition off the back. That arrangement usually costs less disruption than forcing ducts into spaces the framing does not accommodate, and each part of the house gets equipment suited to it.
Where Each Project Continues
Ductless work, whether one head or a multi-zone system, runs through ductless mini-split installation. Central equipment on an existing duct system belongs with central AC installation. Where the ducts exist but one floor is out of step with the rest, the answer may be neither, and zone control systems address that directly. Service on either type is handled through the matching repair path, ductless or central.