The short answer
The main types are single split, multi-split, portable, and ducted (with VRF for larger buildings). A single split cools one room from one outdoor unit; a multi-split runs several indoor units from one outdoor unit; portables are self-contained but noisier and weaker; ducted systems hide the unit and deliver air through concealed ductwork. All but the portable use refrigerant pipework and must be installed by an F-Gas-certified engineer.
“Air conditioning” is not one product. The same refrigeration cycle is packaged in several formats that differ in cost, efficiency, noise and how many rooms they serve. Choosing the right type is the single biggest decision before you ask for quotes, because it sets the price band and the disruption involved. This guide explains each common type, where it fits, and roughly what it costs in 2026.
Types of air conditioning at a glance
- Single split One room, £1,500–£3,000 installed
- Multi-split Several rooms, £3,000–£6,000+
- Portable Self-contained, £300–£600
- Ducted Concealed, whole-floor coverage
- VRF Larger / commercial buildings
- Fixed installs Need an F-Gas-certified engineer
Single split systems
A single split is the most common domestic choice and a sensible default for most people starting out. It pairs one wall-mounted (or sometimes floor- or ceiling-mounted) indoor unit with one outdoor condenser, linked by a thin run of refrigerant pipe and a drain. It cools a single room and, if it is a reverse-cycle model, heats it too — quietly and efficiently, because the noisy compressor lives outside. Of the fixed systems it is the least disruptive to install, usually needing only a small core hole through the wall for the pipework. It typically costs £1,500–£3,000 fitted, depending on the capacity needed and how far the indoor and outdoor units are apart. If you are weighing one larger system against several small ones, see split vs multi-split air con.
Multi-split systems
A multi-split connects several indoor units — commonly two to five — to a single outdoor unit. It suits homes that want cooling in several rooms without a row of separate outdoor boxes cluttering the walls, and it keeps refrigerant pipework tidier. Each indoor unit can usually be controlled independently, running at its own temperature or switched off while others cool, though on a standard system they all cool or all heat together rather than mixing. It costs more than a single split, usually £3,000–£6,000 or higher depending on how many indoor units and the length of the pipe runs. Per room it can work out cheaper than buying several single splits once you reach three or more rooms. Running costs scale with how many indoor units you actually use at once; see multi-room air con cost.
Portable units
A portable air conditioner is a single self-contained box on castors with a flexible hose that vents hot air out through a window. Its main appeal is that it needs no F-gas engineer — it is a sealed, plug-in appliance, so you can buy one and use it the same day, and it can move from room to room. The trade-offs are real and worth understanding before you buy: it is noisier because the compressor is inside the room with you, it is less efficient because the window hose lets some warm outside air leak back in around the seal, and it takes up floor space. Expect to pay £300–£600. It is the right answer for renters, occasional hot spells, or rooms where you cannot fit a fixed unit. For a full comparison see portable vs fixed air con.
| Type | Rooms served | Typical installed cost | F-gas engineer? |
|---|---|---|---|
| Single split | One | £1,500–£3,000 | Yes |
| Multi-split | Several | £3,000–£6,000+ | Yes |
| Portable | One (partly) | £300–£600 | No |
| Ducted | Whole floor | Higher, project-specific | Yes |
Ducted and concealed systems
A ducted system hides the indoor unit in a loft or ceiling void and delivers conditioned air through grilles fed by concealed ducts, so that only slim grilles are visible in each room. It is the most discreet option by far and suits new builds or major renovations where the ductwork and service access can be designed in from the start. It is more expensive and more involved than a split, and the price is project-specific because it depends on duct lengths and the number of outlets. Retrofitting it into a finished home is possible but disruptive. See ducted air conditioning explained for the full picture.
VRF and larger buildings
VRF (variable refrigerant flow) systems scale the multi-split idea up to offices, shops and large houses, with one or more outdoor units serving many indoor units. Their distinguishing feature is the ability to heat some zones while cooling others at the same time — useful in a large building where a sunny side needs cooling while a shaded side needs warmth. They are a commercial-grade choice rather than a typical home fit, and they are designed, installed and commissioned as a project by specialist engineers.
Which type should you choose?
The right type follows from how many rooms you need to cool and your circumstances:
- Choose a single split for one key room such as a bedroom or home office — the simplest, cheapest fixed option.
- Choose a multi-split for three or more rooms served from a single outdoor unit, keeping the building tidy.
- Choose a portable for renting, occasional use, or where you cannot fix to the wall.
- Choose ducted for a discreet whole-floor solution during a build or major renovation.
This page is general information, not a site-specific survey. The best type depends on your rooms, your walls, the siting of the outdoor unit and your budget, so confirm the choice with a quote from an F-Gas-certified installer who has surveyed the property. To narrow down by use and room, see air con for the home.
Not sure which type fits?
List the rooms you want cooled and how often, then ask an F-Gas-certified installer to survey before you pick a system type.
Frequently asked questions
What is the most common type of home air conditioning?
The single split — one indoor unit and one outdoor unit serving a single room — because it is efficient, quiet and the least disruptive fixed system to install.
Do all types need an F-gas engineer?
All fixed systems do, because they contain fluorinated refrigerant. Only sealed plug-in portable units can be set up without a certified engineer.
Is a multi-split cheaper than several single splits?
Often, because one outdoor unit serves several rooms, reducing wall clutter and sometimes cost — though it depends on layout and pipe runs.
What is VRF air conditioning?
Variable refrigerant flow: a scalable system for larger or commercial buildings that runs many indoor units from shared outdoor units and can heat and cool different zones at once.
Sources & further reading
- Energy Saving Trust — cooling and air-to-air heat pump system types
- gov.uk — GB F-gas regulations on refrigerant-containing equipment
- Daikin / Mitsubishi Electric — manufacturer technical data on split, multi-split and VRF ranges
- gov.uk — Planning Portal guidance on external units
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.