The air conditioning installation process, step by step

Step one: the survey

A proper installation starts with someone visiting the property, not a quote generated from photos or a floor plan alone. The survey covers room dimensions, glazing and orientation, existing electrics, wall construction, and crucially where the outdoor unit can realistically sit and how pipework would route between indoor and outdoor units.

This is also when unit type is discussed properly, whether wall-mounted, cassette or ducted suits the space, and any planning considerations are flagged, such as whether the property is listed or in a conservation area. Skipping this stage in favour of a desk-based estimate is the single biggest cause of quotes changing later.

Step two: the quote

A proper quote following a survey should be itemised, showing unit specification, indicative installation cost, and any additional work identified, such as electrical upgrades or bracket reinforcement for an awkward outdoor unit location. It should also make clear what's included, such as commissioning and initial handover, versus what would be extra, like an ongoing maintenance contract.

This is the point to ask questions about warranty terms, F-Gas certification of the engineers doing the work, and expected installation timescale, since all of these affect the real value of a quote beyond the headline figure.

Step three: preparation before install day

Once a quote is accepted, equipment is ordered and, for commercial jobs in particular, any access arrangements, isolations or out-of-hours working needs are confirmed with the site. For domestic jobs this is usually simpler, mainly confirming a date and making sure the areas where indoor and outdoor units will be fitted are clear.

It's worth clearing furniture away from walls where indoor units will be mounted and making sure external access to the proposed outdoor unit location is available on the day, since delays here push the whole job back.

Step four: install day

• Indoor unit mounted and outdoor unit positioned according to the survey, with brackets fitted securely to suit the wall or ground surface.
• Refrigerant pipework, drainage and electrical cabling run between the two, usually through a single core-drilled hole rather than multiple penetrations.
• Pipework insulated and, where visible, boxed in neatly rather than left exposed.
• System pressure tested and evacuated to remove air and moisture before refrigerant is introduced, which is essential for long-term reliability.
• A single domestic wall unit installation is typically completed within a day; larger or multi-unit commercial jobs take longer and are usually scheduled and communicated in advance.

Step five: commissioning, handover and aftercare

Commissioning involves checking refrigerant charge, verifying airflow and temperature performance, and confirming controls and any app connectivity work as expected. A proper handover talks the client through day-to-day operation, filter cleaning, and what to do if something seems wrong, rather than simply leaving a manual on the side.

Aftercare is where value shows over time, not just at install. A system serviced annually under a maintenance contract keeps its warranty valid and its efficiency high for years, whereas one left untouched after installation is more likely to develop faults that could have been caught early. If you're planning an installation and want to understand exactly what to expect at each stage for your specific property, get in touch for a free quote and survey, and we'll talk you through the whole process before you commit to anything.