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How AC Installation Works: Step by Step

Mounting a unit on a wall and connecting it to a box outside sounds simple, but a proper air conditioning installation is really a sequence of steps that all have to line up correctly, from measuring the space to pressure-testing the refrigerant circuit for leaks. If you are arranging AC for a Prague apartment, house or office for the first time, it helps to know what actually happens on installation day, how long it takes, and what to have ready beforehand.

What installation actually involves

Installation is a lot more than fixing a box to a wall. A technician has to choose a workable location for both the indoor and outdoor unit, plan a route for the line through the wall or facade, run the refrigerant piping alongside the power and signal cable, and arrange condensate drainage so it does not leak anywhere it shouldn't. The whole refrigerant circuit then has to be pressurized, checked for leaks, and charged with a precise amount of refrigerant - only after that does the unit get switched on and tested. The quality of an installation tends to show up over the following months of use, not on day one.

The process, step by step

The work itself breaks down into five steps:

• Enquiry and free survey. Describe the space over the phone or through the contact form, ideally with a few photos of the room. A technician then visits in person, measures the distance between the planned indoor and outdoor locations, and checks where the line can run.
• Proposal and fixed quote. Based on the survey, we recommend the right unit type and output and confirm exactly where both parts will go. You get a fixed price with no hidden items, so you know upfront what you are paying for.
• Mounting the indoor and outdoor units. The indoor unit is fixed to the agreed wall, and the outdoor unit is mounted on the facade, a balcony rail, or a bracket. The refrigerant line, cabling and condensate route are run between the two.
• Charging the refrigerant circuit. The circuit is connected, pressurized with nitrogen, and tested for leaks. Only once it passes that test is the refrigerant - commonly R32 - charged in, in a precisely specified amount.
• Test run and handover. The unit is run in both cooling and heating mode, condensate drainage and noise are checked, the controls are explained, and documentation plus a warranty are handed over.

How long it takes

A single split installed in an apartment or small office usually takes 3 to 6 hours and is handled by one crew in a single day. More demanding jobs - a multi-split system with several indoor units, a longer run across multiple floors, or a larger commercial installation - can take one to two days. Once you accept a quote, installation is normally scheduled within 48 hours, so you are not waiting weeks to get cooling in place.

What to prepare beforehand

Clear access to both the planned indoor wall and the outdoor location - balcony, facade or roof - makes the job faster and lets the crew work without obstacles. It helps to have a rough idea in advance of where you would like each unit, though the technician will confirm what is actually feasible on site. Someone should be available to open up and confirm placement on the day itself. And if you live in a shared apartment building, check whether the facade needs SVJ approval before you lock in a firm date - see our guide on installing AC in a Prague apartment building for how that process works.

The one thing worth checking about any installer

Because the job involves handling pressurized refrigerant, it should only be carried out by a technician holding a valid F-gas certification for working with refrigerants. It is a reasonable question to ask any company before you book a date - a properly certified technician is what keeps the refrigerant circuit leak-tight and the unit reliable for years, not just on the first day. For a full breakdown of what each of these steps costs, see our guide to AC installation cost in Prague .