Air-conditioning indoor-unit types

Indoor-unit format affects installation, access and air distribution. It does not determine whether the unit has enough capacity for the room.

UK residential split systems are available with high-wall, floor-console, ceiling cassette and concealed ducted indoor units. Different indoor-unit types can be available on the same multi-split platform, subject to the manufacturer’s compatibility data.

High-wall units

A high-wall unit is mounted at high level and discharges directly into the room. The proposed position needs suitable wall space, clear airflow and access to the filters.

Floor-console units

A floor console sits low on a wall and can be used where a high-wall position is unavailable. Its position still needs clear airflow and suitable access.

Compact ceiling cassettes

A compact cassette sits within a ceiling void and supplies air through a visible grille. It needs sufficient void depth and service access.

Concealed ducted units

A concealed ducted unit is connected to supply and return grilles. The main unit is concealed, but the grilles and service access remain.

Its performance depends on the complete air path. Duct resistance, fan duty, return-air provision and acoustic treatment all affect airflow and sound. The condensate route and service access also need to be included in the design.

Capacity and airflow

Indoor-unit type is separate from capacity. It also does not prove that conditioned air will reach an adjacent closed room.

Airflow, access and drainage

The design information for each indoor unit covers:

• indoor-unit format and proposed position
• airflow and return-air arrangement where applicable
• ceiling-void requirements for cassette units
• filter and service access
• condensate route
• ducts, grilles and acoustic treatment where applicable

Related entries

• Single-split and multi-split air conditioning
• Air-conditioning cooling load and sizing
• Air-conditioning condensate drainage
• Air-conditioning maintenance and filters