How to install air conditioning: the essential guide
Air conditioning installation is a straightforward process when it’s handled by a qualified professional. In fact, while every home is slightly different, the steps are fairly consistent — from getting a quote through to installation and final checks.
With British Gas and our trusted partners, the aim is to keep everything simple, with minimal disruption to your home.
Published on 22nd May 2026 by:
Edward Weatherall, Commercial Delivery Manager, Installs
How does air con work?
Air conditioning works by removing heat from inside your home and releasing it outside. Instead of creating cold air, it continuously moves heat from one place to another.
Warm air from your room is drawn into the indoor unit, where it passes over cold coils containing refrigerant. This refrigerant absorbs the heat and carries it outside to the outdoor unit, where the heat is released. The cooled air is then circulated back into your home and the cycle repeats until your chosen temperature is reached.
Installing air conditioning: initial steps
Before your installer can get started, there are a couple of steps they must check off.
Getting a quote
The first step is getting an initial idea of cost and suitability. We’ll ask you just a few questions about your home to give you an estimated cost. This helps indicate what type of system may work best and gives a starting point before anything is arranged.
Expert advice and assessment
Next comes a more detailed review of your property. You'll be asked to share photos of the rooms where you want air conditioning installed. This helps assess layout, access and the best positions for indoor and outdoor units.
If needed, a short video call may also be arranged to confirm details and refine the design. This step helps make sure the system is properly planned for your home.
What's involved in the air con installation process?
Once the initial checks have been made, here’s a look at what you can expect from your installer once they get going.
Install the indoor unit
The indoor unit is fitted inside your home, usually on a wall where airflow is most effective and the unit is practical for everyday use. Placement is chosen to balance performance with a neat, unobtrusive finish.
Position the outdoor unit
The outdoor unit is then installed outside the property in a suitable location. This allows it to safely release heat from your home while maintaining good airflow around the unit.
Connect pipework and electrical components
Once both units are in place, installers connect the refrigerant pipework and electrical wiring between them as well as connecting to the mains electrical supply. These connections allow heat to be transferred from inside your home to the outdoor unit.
Check the system is sealed and operating correctly
Finally, the system is fully tested. Your installer will check that all connections are sealed, the refrigerant is flowing correctly, and the system is heating and cooling as expected before everything is signed off.
How long does installation take?
In most cases, the physical installation takes around one day once work begins, but more complex installations with multiple indoor units will take longer. From initial quote through to completion, the full process typically takes around two weeks with British Gas, depending on availability and your home setup.
What’s needed for installation?
To install air conditioning, you generally need:
- Space for an indoor wall-mounted unit
- An external area for the outdoor unit
- A route for pipework between units
- Access to a suitable power supply
Most of this is assessed during the home survey so very little preparation is needed from you.
Do you need a professional to install air con?
It’s strongly advised that all air conditioning systems must be installed by qualified professionals. This guarantees that the system is fitted safely, works efficiently, and meets all legal and warranty requirements. It also helps prevent issues with refrigerant handling and electrical connections.
Install air con with British Gas
Installing air conditioning is much simpler when it’s fully managed by experts, from initial advice through to installation and aftercare.
With British Gas, you can get an online quote, receive tailored guidance for your home and have your system installed by our trusted partners.
Flexible payment options are available subject to status and credit checks, and all installations come with a 5-year manufacturer guarantee on air conditioning units that are serviced annually, giving added confidence long after the work is complete.