Air Conditioning Installation: 2026 cost and what it includes

A standard split air conditioning installation is a clearly defined package. The price includes the installation and commissioning of both units, one wall penetration through a standard wall, copper interconnecting pipework and electrical wiring up to 3 metres, gravity-fed condensate drainage to the outdoor unit, a wall bracket for the outdoor unit, aesthetic surface trunking with fittings, user training, and a commissioning record. You can find a complete list and current prices in the price book above.

Three groups of work are typically charged as extras:

• Longer pipe runs. Every metre over the standard 3 metres is charged based on the unit's capacity, as more powerful units require larger diameter pipework.
• Building work. Chasing channels into walls and making good, a second hole, or core drilling through reinforced concrete or externally insulated walls.
• Non-standard conditions. Installation on a roof, under a window, or at a height above 3 metres requiring scaffolding or a platform. The surcharge is determined by the complexity during a site survey.

This is precisely why itemised quotes make more sense than a single lump sum. The customer can check such an offer and the tradesperson can justify it, because every metre and every hole has its place.

A 'split' system consists of one indoor and one outdoor unit. It is the cheapest, most reliable, and easiest solution to service. A 'multi-split' connects two or more indoor units to a single outdoor unit, most commonly two or three in residential properties. This saves space on the facade or balcony, but the pipe runs are longer, there are more connections, and a fault in the outdoor unit will shut down the system in all rooms at once. For two adjacent rooms, the difference is often small, but for three rooms, a multi-split starts to make sense.

If you're looking for air conditioning for a flat with installation, always factor in two parts of the price: the equipment, based on brand and capacity, and the installation, based on the price list. If you receive an 'all-in-one' price for the unit and installation, be sure to break it down. These offers often hide very short pipe runs, cheap insulation, or the lack of proper evacuation and pressure testing.

A flat in a block of flats. The pipe run is usually short, with the outdoor unit placed on a balcony or on the facade directly behind the indoor unit. The constraints are more often legal and structural. The external wall and facade are common parts of the building, so if you are a leaseholder, you must verify the requirements and obtain consent, a 'Licence for Alterations', from your freeholder or managing agent before ordering the installation. In concrete-panel buildings, horizontal chases in load-bearing walls are not typically made without a structural engineer's report and the freeholder's consent. The pipe run is usually concealed in trunking or passed directly through the wall behind the indoor unit. Flats do not benefit from permitted development rights, so planning permission may be required for any external unit. Always check with your local planning authority.

A house. You do not need your neighbours' consent, but pipe runs can be longer, often passing through insulated walls, and the outdoor unit may be ground-mounted or on a bracket near a patio. With an insulated facade, the wall penetration must be sealed correctly to prevent thermal bridging and water ingress behind the insulation. The condensate can be routed to a soakaway or a rainwater drain. For multiple rooms on different floors, a multi-split or two separate split systems are more commonly used. Installation is often covered by permitted development rights, but it is always wise to check with your local planning authority, particularly for listed buildings and conservation areas, or if the unit will be close to your boundary.

People often ask about the unit's capacity along with the price, which is the right approach. An undersized unit will run at full power constantly, while an oversized one will cycle on and off frequently when the cooling demand drops below its lowest modulated output. The table below gives a rough guide based on floor area, assuming a standard ceiling height and average insulation. Large south-facing windows, a room in a converted loft, or an office with several people will push the required capacity up a level. The final design should be specified by the installer during a site survey.

The interconnecting pipework is connected to the units with flared joints; any other joints in the run are made by brazing. The entire circuit operates under high pressure and must remain hermetically sealed for the lifespan of the equipment. Modern units primarily use R32 refrigerant, with newer models also using R290. High-GWP refrigerants such as R410A are being phased out of new equipment. UK placing-on-the-market rules are evolving, so it is best to check the current requirements at the time of purchase and installation.

• Wall thickness of 0.8 mm. For common pipe dimensions of 1/4", 3/8", and 1/2", this is the standard for refrigeration pipework according to EN 12735-1, designed for the pressures of modern refrigerants.
• 99.9% copper purity. Refrigeration-grade Cu-DHP copper is annealed, internally dried, and sealed at the factory with plugs to prevent moisture or dirt from entering.
• Vapour-proof insulation. Closed-cell insulation prevents condensation from forming on the cold pipework. Outdoors, it must be UV-resistant, otherwise it will disintegrate after two or three seasons.

Why not use standard plumber's copper from a DIY store? Not because it's too thin, as EN 1057 copper often has a 1 mm wall thickness. The problem is that it is usually supplied in a hard temper, making it difficult to bend. Its interior is not dried or sealed, and its metric dimensions do not fit imperial flare nuts. Moisture and impurities in the circuit will contaminate the compressor oil and are the most common cause of a seized compressor.

Copper pipe should be bent using a proper pipe bender or spring to precise radii. A kink under the insulation may not be visible, but the restricted cross-section increases noise, compressor load, and energy consumption. An overly short pipe run is just as damaging. Manufacturers specify a minimum line length because the pipework helps to dampen vibrations and ensures proper oil distribution within the circuit.

When cooling, the indoor unit removes moisture from the air, and this condensate must drain away somewhere. In a block of flats, condensate is the most common cause of disputes with neighbours and damage to walls.

• A fall of at least 1%. That's one centimetre for every metre, along the entire length and with no upward gradients.
• No unnecessary bends. Every high point can trap dirt, leading to a blocked drain over time.
• Insulated drain hose. Airborne moisture will condense on an uninsulated hose inside a wall chase, leading directly to damp within the wall structure.

If the drain doesn't have a consistent fall, water will find its way where it shouldn't, almost always into the wall beneath the indoor unit. Connecting to the flat's internal waste system is a neat solution, but only through a suitable trap with a dry seal or a waterless membrane, which will prevent odours even if the water in a traditional trap evaporates in winter. Terminating the drain on the facade is the simplest option, but if water drips onto a neighbour's balcony or a public footpath, conflict is certain. In winter, water produced outdoors during the heating and defrost cycle must also be safely drained to prevent slip hazards caused by ice.

A condensate pump is the solution where a gravity drain isn't possible. However, it operates cyclically and can be heard in a quiet room. Only choose a pump for a bedroom or children's bedroom if there is truly no other option, and always opt for a quiet model.

An electrical supply of up to 3 metres is part of a standard installation. A longer supply, typically a new dedicated circuit from the consumer unit, is charged as an extra per metre. The circuit breaker (MCB) and cable size are chosen according to the manufacturer's requirements and installation conditions, such as the length of the run and how the cable is installed. For units up to 3.5 kW, a 10 A to 16 A MCB and a 1.5 mm² or 2.5 mm² 3-core cable are typical. The stranded conductors of the interconnecting cable must be terminated with ferrules, otherwise they can loosen under the terminal screw over time, causing the connection to overheat. In England and Wales, a new electrical circuit is notifiable work under Part P of the Building Regulations and must be installed and certified by a registered electrician.

In a block of flats, both the outdoor unit and the hole through the wall affect common parts of the building. If you are a leaseholder, you will almost certainly need formal consent from the freeholder or managing agent before any work begins, a process known as applying for a 'Licence for Alterations'. Installing a unit without permission can lead to enforcement action and the cost of removal. For installations on a balcony or loggia, the rules might be simpler, but you should still check with your managing agent in advance, as the hole still passes through a shared structural wall. Flats do not benefit from permitted development rights, so planning permission may be required for any external unit. Always check with your local planning authority, particularly if your property is listed or in a conservation area.

A request to your freeholder or managing agent should contain at least the following information:

• The leaseholder's name, flat number, floor, and contact details.
• The make, model, and capacity of the unit, plus the dimensions, weight, and noise level (in dB) of the outdoor unit.
• The precise proposed location of the outdoor unit, ideally with a photograph or sketch.
• The proposed route for the pipework, the method of drilling, and how the condensate will be drained.
• Details of the installation company, including their F-gas company certificate number, and the lead engineer's F-gas qualification.
• A commitment to return the facade to its original condition upon removal and to be responsible for any damage caused.

Example wording: “I am writing to request consent for the installation of an air conditioning outdoor unit at [location] for flat no. [number], and for a core drill of [diameter] mm through the external wall. Condensate will be drained via [method]. The installation will be carried out by the F-gas certified company [Company Name, certificate no.]. I undertake to bear all maintenance costs and to restore the facade to its original condition upon any future removal.” Always verify the required format and content with your managing agent before submitting. This is general information and not legal advice.

Air conditioners containing refrigerants like R32 or R410A contain fluorinated greenhouse gases. Any work on the refrigerant circuit, including flaring pipes, evacuating the system, and opening the service valves, may only be carried out by a person with a valid F-gas certificate, for example City & Guilds 2079 Category I. The installation company must also hold F-gas company certification. Manufacturers will usually void the warranty without proof of professional installation by a certified engineer. While you can prepare chases or mount the bracket yourself, the electrical supply is a job for an electrician, and connecting the refrigerant circuit and commissioning the system must be done by a certified technician who will record the values in the commissioning log.