Installing air conditioning in the UK: F-gas engineers, planning and noise

You can set up a portable air conditioner yourself. A split system – indoor and outdoor unit connected by refrigerant pipes – raises three questions in the UK: who is allowed to connect the refrigerant circuit, whether you need planning permission, and how loud the outdoor unit can be. This guide covers each, with a focus on England.

1. Who can install a split system?

Split air conditioners usually contain a fluorinated refrigerant (F-gas), commonly R32. In Great Britain you must hold your own F-gas qualification to install, service, maintain, leak-check or decommission equipment containing F-gas – even if you work for someone else ¹. The qualifications come in categories ¹:

Qualifications are issued by accredited bodies such as City & Guilds, BESA and LCL Awards ¹. Ask your installer for their F-gas certificate and check that the quote includes:

• the refrigerant type and charge;
• pulling a vacuum and a pressure/leak test before commissioning;
• a commissioning record.

Quick-connect kits: the DIY risks

Some split systems are sold with pre-charged pipes and quick-release couplings and marketed as DIY-friendly. They still contain F-gas and still involve connecting a refrigerant circuit, which in Great Britain is work for someone with an F-gas qualification ¹. Beyond the rules, there are real risks:

• Leaks. A coupling that isn’t fully seated or a kinked pipe lets refrigerant escape. Cooling gradually worsens and the gas ends up in the atmosphere.
• No leak test. Without a vacuum and pressure test, a slow leak may only show up weeks later.
• Flammability. R32 is mildly flammable. A leak in a small, poorly ventilated room is another reason to use a professional.
• Warranty. Many manufacturers only honour the warranty if a qualified engineer installed the system.
• Condensate and electrics. A badly routed condensate drain drips down the wall or inside. Larger units need their own circuit, and adding a new circuit in a home in England is notifiable electrical work under Part P of the Building Regulations.

If a qualified installer isn’t an option, a portable unit or a through-wall monoblock (no outdoor unit, no refrigerant work on site) are the alternatives you can fit yourself.

Refrigerants: what’s changing

In the EU, new split air-to-air systems up to 12 kW will have to use refrigerants with a GWP below 150 from 1 January 2029, and must be free of F-gases from 2035 ². R32 has a GWP of around 675, so it falls on the wrong side of that line in the EU. Great Britain runs its own F-gas regime and is not bound by those EU dates, but manufacturers are already shifting towards propane (R290): of the 996 air-to-water heat pumps with a known refrigerant in our database, 82% already use R290. Existing systems can continue to be used and serviced.

2. Planning permission in England

Since 29 May 2025, the permitted development rights for air source heat pumps in England also cover units that can provide cooling, so air-to-air heat pumps – in practice most reversible split air conditioners – can benefit from them ³. Key points ³:

• the installation must comply with the MCS 020(a) noise standard;
• the rule that units must be at least 1 m from the property boundary has been removed;
• detached houses can have two units instead of one;
• the maximum unit size for houses is 1.5 m³ (previously 0.6 m³).

These changes apply only to England; Scotland, Wales and Northern Ireland continue to follow their own rules and the original MCS 020 standard ³. Permitted development has further conditions, for example for listed buildings, conservation areas, flats and the siting of units. If in doubt, ask your local planning authority or apply for a lawful development certificate.

Leaseholders and tenants: even where planning permission isn’t needed, you will usually need consent from the freeholder or landlord for an outdoor unit and holes through an external wall.

3. Noise: MCS 020(a)

Under permitted development, noise is assessed using MCS 020(a), which includes a method to account for up to two air source units in the calculation ³. The calculation starts from the sound power level of the outdoor unit (on the energy label and product fiche) and takes into account the distance to the nearest neighbouring window and reflective surfaces nearby. A unit tucked into a corner between two walls will be noticeably louder at the neighbour’s window than one mounted on an open wall. Ask your installer to show you the MCS 020(a) result for the proposed position.

4. MCS certification and grants

An installer does not need MCS certification simply to fit air conditioning. But if you want the £2,500 Boiler Upgrade Scheme grant for an air-to-air heat pump, the installer must be MCS-certified, the property must be in England or Wales, and the system must replace fossil-fuel or electric heating ⁴. See our guide to heating with air conditioning for the full conditions.

Checklist for your quote

1. The engineer holds an F-gas qualification (Category 1 or 2).
2. Refrigerant type and charge are stated.
3. Outdoor unit position and MCS 020(a) noise result have been discussed.
4. Condensate drain and electrical connection (including a new circuit if needed) are included.
5. Vacuum, pressure test and commissioning record are included.
6. If you want the BUS grant: the installer is MCS-certified and will make the application.

To work out what size unit your room needs, see our sizing guide.