Split air conditioners: how to choose the size, price and installer
A split is the most efficient and quietest way to cool a room. Here is what size you need, what it costs installed and what to check before you sign the quote.
By the ClimaEasy team. Updated
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What a split is
A split divides the air conditioner into two parts: an indoor unit on the wall of the room and an outdoor unit with the compressor, on the facade, a terrace, a courtyard or the roof. The two are connected by refrigerant pipes and a cable that run through the wall.
Because the compressor, the noisy part, is outside, a split is much quieter than a portable. And because heat goes straight outdoors, it is also more efficient.
- 1x1 split: one outdoor unit and one indoor unit. The most common setup, for a living room or a bedroom.
- Multi-split (2x1, 3x1…): one outdoor unit for several indoor units. It takes up less facade, but if the outdoor unit fails, every room loses its cooling.
Almost every domestic split today is an inverter: it varies the compressor speed instead of switching it on and off, which lowers consumption and keeps the temperature steadier.
What size to choose
The rule of thumb installers use in Spain is 100 frigories per square metre (1 kW is about 860 frigories), with more margin if the room gets a lot of sun, is on the top floor or has high ceilings. Splits come in standard sizes, usually shown in kW:
| Split size | Equivalent to | Approximate room size |
|---|---|---|
| 2.5 kW | About 8,500 BTU/h | Up to about 20 m² |
| 3.5 kW | About 12,000 BTU/h | Up to about 30 m² |
| 5 kW | About 17,000 BTU/h | Up to about 40 m² |
| 7 kW | About 24,000 BTU/h | Large or very sunny living rooms |
For your room, use our cooling power calculator. A unit that is too small won't cope on the hottest days, and one that is too big will cool in bursts and use more energy than it needs to.
What a split costs installed
These are the approximate ranges published by installers and price comparison sites for Spain in 2026, for a basic installation (units close together and easy access):
| Installation | Approximate price |
|---|---|
| Installation only for a 1x1If you already have the unit | €300 to €500 |
| 1x1 split with unit and installation | €600 to €1,650 |
| 2x1 multi-split with units and installation | €1,350 to €3,000 |
The price goes up when the units are far apart (more than about 5 metres of pipe), the pipes have to run along the facade or work at height or scaffolding is needed. Always ask for the quote to spell out what the "basic installation" includes.
Efficiency and the energy label
On a split's energy label you'll see two key figures:
- SEER: seasonal efficiency in cooling mode. The higher it is, the less energy it uses for the same cooling.
- SCOP: seasonal efficiency in heating mode. This is the figure that matters if you'll also use it for heating.
Two units of the same size can use very different amounts of electricity. If you'll run it for many hours, a better energy class usually pays back the price difference within a few years. Work out your case with the running cost calculator.
Heat pump: cooling and heating in one unit
Almost all domestic splits are heat pumps: in winter they reverse the cycle and heat the room. It's one of the most efficient forms of electric heating, because for every kWh of electricity they deliver several kWh of heat.
To use it in winter, check the SCOP on the label and the lowest outdoor temperature at which the unit works well, especially if you live somewhere with frost.
What to ask the installer
F-gas certificate
In Spain, units with fluorinated refrigerants must be installed by a professional holding the certificate required by Royal Decree 115/2017. Ask for it before you hire them.
An itemised quote
The unit, metres of pipe included, brackets, drainage, any electrical work and the price of extra metres.
Where the outdoor unit will go
Where it will sit, how condensation water will drain and whether noise or drips could bother a neighbour.
Warranty and commissioning
Who is responsible if there's a leak, and what warranty covers the unit and the installation.
Permissions
If the outdoor unit goes on the facade or another common area of the building, you'll normally need your community of owners' permission. If you rent, you'll also need your landlord's written consent. We explain it in permissions for installing air conditioning. If you can't get them, see the no-building-work options.
Frequently asked questions
What size split do I need for 20 m²?
As a guide, about 2,000 frigories/h, which matches a 2.5 kW split. If the room gets a lot of sun or is on the top floor, allow about 15% more.
How much does it cost to install a split in Spain?
According to the ranges published by the sector for 2026, a basic 1x1 installation costs €300 to €500 if you already have the unit, and €600 to €1,650 including the unit.
Can I install a split myself?
It isn't advisable and, in general, isn't legal in Spain: handling the refrigerant circuit requires the F-gas certificate under Royal Decree 115/2017. A professional installation is also usually needed to keep the warranty.
Can a split be used for heating?
Yes, if it's a heat pump, like the vast majority of domestic units. To see how well it heats, check the SCOP on the energy label.