The two approaches in simple terms
A multi-split system connects several indoor units to shared outdoor equipment. The indoor units can be wall-mounted, floor-mounted, cassette or concealed formats, depending on the chosen range and design.
A ducted system uses concealed indoor equipment and distributes conditioned air through ducts to supply grilles, with return air routed back to the unit. A property can also combine ducted and visible units where one architecture does not suit every room.
Ducted does not mean invisible. Grilles, access panels, controls and sometimes bulkheads remain part of the finished design.
Compare the finished room, not the brochure image
Multi-split designs often leave a visible indoor unit in each room, although alternative indoor-unit styles and carefully selected positions can integrate well. Ducted systems can reduce the visible equipment to grilles and controls.
The discreet appearance of a ducted system depends on good grille selection, alignment and ceiling coordination. Poorly placed grilles, oversized bulkheads or prominent access panels can undermine the intended finish.
Ceiling space and route feasibility can decide the answer
Ducted systems need space for the indoor unit, ducts, insulation, return air, plenums, drainage and service access. Existing homes may not have continuous ceiling voids or suitable routes between rooms.
Multi-split systems avoid extensive air ducts but still require refrigerant pipework, cable and condensate routes from each indoor unit. Shared outdoor equipment can reduce external-unit count, while route lengths and technical limits still need checking.
Zoning and everyday control should match how rooms are used
Many multi-split indoor units can be controlled by room, although units connected to a common system may need to operate in the same overall heating or cooling mode. Available capacity is shared and the design should reflect likely simultaneous use.
Ducted systems can serve one zone or several zones with dampers and a suitable control strategy. Zoning adds design and commissioning requirements. A single sensor for rooms with different loads or schedules may not provide the expected comfort.
Sound depends on the whole air path
With visible indoor units, sound data, fan speed, mounting and placement are central. With ducted systems, fan sound, air velocity, grille selection, duct design, attenuation and the position of concealed equipment all matter.
Concealing a unit above a bedroom or placing return air where sound transfers between rooms can create problems that are not obvious from product data. Acoustic design should be specific to the layout.
Design access before closing ceilings
Visible units are usually straightforward to inspect and clean. Concealed equipment needs appropriately sized access panels for filters, electrical components, drainage and future repairs. Ductwork and grilles may also need inspection or cleaning depending on the application.
Outdoor equipment, branch components and controls should remain accessible. A visually perfect installation that requires destructive access for routine service is not a successful design.
High-level comparison
| Decision | Multi-split | Ducted |
|---|---|---|
| Visible finish | Indoor units visible unless concealed formats are selected | Main equipment concealed; grilles, controls and access panels visible |
| Building space | Pipe, cable and drainage routes required | Ceiling or service space required for units, ducts and return air |
| Room control | Commonly individual indoor-unit control, subject to shared mode and capacity | Depends on zone design, dampers, sensors and controls |
| Installation impact | Often focused routes to each room | Can require substantial ceiling coordination and making-good |
| Maintenance | Indoor units generally visible and accessible | Access panels and service routes must be designed deliberately |
| Typical fit | Several rooms where visible units and coordinated routes are acceptable | Projects prioritising a discreet finish with suitable ceiling space |
A practical decision sequence
- Define the rooms, loads, schedules and desired level of individual control.
- Map ceiling voids, service spaces, external positions, pipe routes and drainage.
- Decide what can remain visible and where grilles or units should sit.
- Compare sound risks at bedrooms and quiet spaces.
- Confirm maintenance access before approving concealed work.
- Compare programme, making-good, controls, commissioning and whole-life support.
- Use a mixed design if it solves the building better than forcing one architecture everywhere.
