Wall unit (mono-split)
Mounted high on a wall, usually opposite or beside the seating area. Affordable, quick to fit, huge choice. Visible in the room, but the best capacity per euro.
Systems
Air conditioning systems compared
Unit type, capacity and placement decide how well a system performs later. Here is what actually matters when choosing.
The basic principle
A split air conditioner consists of an indoor unit in the room and an outdoor unit on the façade, terrace or roof. The two are linked by two slim copper pipes, a control cable and a condensate drain. Refrigerant circulates through the loop, absorbs heat, is compressed and releases that heat elsewhere.
Efficiency and comfort hinge on inverter technology: instead of switching on and off constantly, the compressor modulates down as soon as the target temperature is reached. That saves electricity, keeps the temperature steady and is far quieter than older systems.
The unit types in detail
Multi-split
One outdoor unit serves several rooms. Indoor unit types can be mixed, for example wall unit in the living room and floor unit in the bedroom. Saves façade space, needs longer pipe runs.
Floor unit
Sits like a radiator against the wall. Very pleasant for heating, because warm air rises from below. Ideal under window sills or in rooms with sloping ceilings.
Ceiling cassette
Distributes air on four sides and is practically invisible. Common in offices, practices and shops with grid ceilings.
Ducted unit
The unit sits in the ceiling and feeds several rooms through ducts. The most elegant solution, best planned during construction or a full renovation.
Portable unit
The exhaust hose in a tilted window keeps drawing warm air back in. High consumption, plenty of noise, modest cooling. Only worth it where fixed installation is not allowed.
How much capacity do you need?
As a rule of thumb, allow 60 to 100 watts of cooling per square metre. Use the higher figure for attic rooms, large south- and west-facing glazing and poorly insulated older buildings.
| Room size | Well insulated, north facing | Sunny or under the roof | Typical unit |
|---|---|---|---|
| up to 20 m² | 1.5 kW | 2.0 kW | Wall unit 2.0 kW |
| 20–30 m² | 2.0 kW | 2.6 kW | Wall unit 2.5 kW |
| 30–45 m² | 2.6 kW | 3.5 kW | Wall unit 3.5 kW |
| 45–60 m² | 3.5 kW | 5.0 kW | Wall or floor unit 5.0 kW |
| over 60 m² / open plan | 5.0 kW | 7.0 kW+ | Ducted or two indoor units |
Oversizing is as unhelpful as undersizing: an oversized unit cycles, dehumidifies poorly and uses more power. Final sizing happens at the site visit.
Refrigerants: R32, R290 and what comes next
The current standard for homes is R32. Its global warming potential is far lower than the older R410A and it needs a smaller charge for the same capacity. The EU regulation on fluorinated greenhouse gases keeps cutting permitted volumes, which is why manufacturers are moving towards natural refrigerants such as R290 (propane).
For you the practical point is simple: do not buy clearance stock running an outdated refrigerant. Spares and recharges get more expensive over the system's life, and it weighs on the property's value.
What to look for on the data sheet
SEER and SCOP
SEER covers cooling and SCOP heating efficiency across a full season. Good units reach 7.0 and 4.6 respectively.
Indoor sound level
In a bedroom the night figure is what counts: 19 to 22 dB(A) on premium units, 28 to 32 dB(A) on entry level.
Heating output at −7 °C
Data sheets quote output at 7 °C. For Luxembourg the figure at −7 °C tells you far more.
Filters and hygiene
Self-cleaning functions, removable filters and optional fine dust or carbon filters make upkeep easier.
Wi-Fi and app
Schedules, remote access and consumption tracking. Check whether the module is included in the price.
Brands
Daikin, Mitsubishi Electric, Panasonic, Toshiba, LG and Samsung are all well covered in Luxembourg for parts and service.
Not sure which type fits?
Describe your rooms briefly. We will suggest two or three concrete options with a price range.