Air conditioning in a flat: split, multi-split or ducted?
Catalunya Servei team ·
In a flat, choosing between split, multi-split or ducted air conditioning depends less on the price of the unit than on three things: how many rooms you want to cool, whether you have (or can add) a false ceiling, and where the outdoor unit can go. Here's what each option means in practice, including the drawbacks the brochures leave out.
The three options at a glance
| Criterion | Single split | Multi-split | Ducted |
|---|---|---|---|
| What it is | One indoor unit, one outdoor unit | Several indoor units, one outdoor unit | One unit in the false ceiling with grilles in each room |
| Building work | Minimal | Little, with longer pipe runs | False ceiling and access hatch |
| Looks | Visible unit on the wall | A unit in every room | Only the grilles show |
| If the outdoor unit fails | You lose one room | You lose every room | You lose the whole flat |
| Indicative installed price | €700–1,300 per system | €1,600–3,000 (2 or 3 indoor units) | €4,000–7,500 for an average flat, excluding ceiling work |
These are market ranges for guidance. Real prices vary a lot with brand, capacity, distance between units and access.
Single split: the simplest
If you only want to cool the living room and perhaps one bedroom, two independent splits are usually the most sensible choice. Each runs on its own, maintenance is straightforward, and if one breaks down the other keeps going. The catch is that each split needs its own outdoor unit, and a small façade or balcony doesn't always have room for two.
Multi-split: when there's no room for more outdoor units
It solves the space problem: one outdoor machine for two, three or more rooms. But it comes with two trade-offs. First, if the outdoor unit fails, you lose cooling everywhere, and that tends to happen when it's working hardest, in August. Second, with just one room switched on it can run less efficiently than a split sized for that room.
It's a good answer when the façade or the building rules limit where units can go, not a default choice.
Ducted: the tidiest, if the ceiling allows
A single indoor unit hidden in the false ceiling, usually above the hallway or bathroom, with supply and return grilles in each room. Nothing is on show, air is spread evenly, and it can be zoned with motorised dampers so empty rooms aren't cooled.
However, you need ceiling height. If the flat has no false ceiling, one has to be built, which means losing a few centimetres in hallways and bathrooms, plus dust and repainting. That's why ducted systems make more sense as part of a full renovation than in a freshly decorated flat.
You also need an access hatch to reach the unit and its filter. We've come across installations fitted without one, where cleaning the filter would mean breaking the plasterboard.
Things to decide before getting a quote
- Where the outdoor unit goes. Façade, balcony, lightwell or roof. Check your building's rules and your town council's regulations first: some buildings and municipalities don't allow units on the main façade.
- Where condensate drains. A proper drain is needed; a hose dripping onto the street or a neighbour's balcony leads to disputes.
- The electrical supply. In older flats, check whether the consumer unit and contracted power can take another appliance.
- Noise. Look at the indoor unit's noise level for bedrooms, and the outdoor unit's if it faces a courtyard with bedroom windows.
- Capacity. Be wary of anyone who sizes it from floor area alone. Orientation, a top floor under the roof, glazing and insulation change the requirement considerably.
What about heating?
All these systems are heat pumps and heat as well as cool. In a well-insulated flat on the Catalan coast they can handle winter comfortably. In Lleida or inland parts of Girona, where winters are colder, they often work better as back-up, or it's worth considering an aerothermal heat pump with underfloor heating or radiators.
The maintenance that's down to you
Whatever the system, indoor unit filters need regular cleaning during the season: a dust-clogged filter makes the unit work harder, cool less and start to smell. On a split it's a five-minute job; with ducted systems, that's exactly why the access hatch matters. The outdoor unit needs clear space around it, with no plant pots or clutter blocking the airflow. And a periodic professional service picks up a refrigerant leak or a blocked condensate drain before it becomes a breakdown.
When we wouldn't change a thing
If you have a fairly new split that works well and your only complaint is that it doesn't reach one room, a second split in that room may be enough. Switching a newly renovated flat to ducted purely for looks is usually very expensive for what it adds.
If you'd like us to take a look at your flat, our air conditioning page explains how we work. We visit, check where the units can go and give you a written quote for the options that make sense.