Air Conditioner Installation - What You Need to Know

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Air conditioning is only as good as it is properly installed. Two completely identical units, one professionally installed according to the manufacturer's instructions and the other installed "from the neighbor for half the price", can differ in cooling efficiency by up to 20-30% in practice, without anything obviously wrong being visible at first glance. The problem may only become apparent after one to two years, when the refrigerant slowly leaks through a loose connection, the compressor becomes overloaded, and a unit that was supposed to last 12-15 years ends up failing after just five. In this article, we will explore what air conditioning installation actually involves, what most affects its cost and complexity, what to watch out for when choosing an installation company, and where people most commonly make mistakes.

Why installation is just as important as the unit itself

A split air conditioning system consists of an indoor unit (the one you see on the wall in the room) and an outdoor unit (the compressor unit mounted on the facade, balcony, or roof). Between them runs copper refrigerant piping with refrigerant, a condensate drain, and electrical cables. The product itself — the compressor, heat exchangers, and electronics — is practically always in good condition from the factory; quality control at reputable brands is at a high level. The weak link in the chain is almost always the installation: the quality of the pipe connections, the thoroughness of system vacuuming, the correct sizing of the refrigerant, and whether the outdoor unit is placed in a way that allows sufficient air exchange.

A leaky pipe connection does not immediately show up from the outside. The refrigerant leaks slowly, and the unit initially cools almost normally, just a bit slower. Only when the refrigerant level drops below a critical threshold does the compressor start operating in an unsuitable mode, noise increases, and eventually a compressor failure occurs — the most expensive component in the entire unit. That is why it is worth giving the same attention to the selection of the installation company and the monitoring of the installation process as you would to the selection of the air conditioning model itself.

How split air conditioning installation proceeds step by step

The majority of wall-mounted split air conditioning installations in apartments or single-family homes follow the same basic procedure. The order of steps may vary slightly depending on the company, but the content always involves the same phases.

Step six — vacuuming and pressure testing — is the most important and also the most frequently skipped step in "cheap" installations. The vacuum pump must run long enough (typically at least 20-30 minutes after the required vacuum is achieved) to remove all moisture and air from the system. If this step is rushed for a few minutes or completely skipped, moisture remains in the system, which over time causes corrosion inside the heat exchangers and freezing of the expansion valve. Ask the installation company directly how long the vacuuming took and whether you have a protocol or at least a photo from the manometer.

What most affects the complexity and cost of installation

The cost of installation in practice consists of a base rate and several additional charges depending on the specific situation in the apartment or house. The standard cost of a wall-mounted split installation — where the indoor unit is within 3 meters of the outdoor unit, a brick or concrete wall, and the ground floor or an easily accessible floor — typically ranges from 150 to 250 euros. Additional charges are added depending on specific circumstances:

Extension of refrigerant piping beyond the standard distance — typically 15 to 25 euros per additional meter of copper piping, including insulation and cabling.
Core drilling through a thicker wall (solid brick, concrete, or multi-layered facade with insulation) — additional charge of approximately 30 to 50 euros compared to drilling through a partition wall.
Separate electrical circuit and circuit breaker for more powerful units, if there is no suitable socket or wiring in the apartment — typically an additional 50 to 100 euros.
Work at height — when the outdoor unit cannot be mounted from a ladder and a platform or climbing equipment is required (high-rise apartments, difficult access to the facade) — the additional charge can range from 50 to 150 euros, and even more in extreme cases, depending on whether special equipment needs to be ordered.

The final typical cost of installing most home split air conditioners thus ranges from 150 to approximately 450 euros. For more complicated installations (multiple indoor units on one outdoor unit, multi-split systems, very long piping runs), the cost can be even higher — in such cases, it is always better to request a specific quote after a site inspection, rather than an estimate over the phone.

Who is allowed to install air conditioning and what to ask companies

The installation and servicing of equipment containing fluorinated greenhouse gases (refrigerants such as R32, R410A, and others commonly used in household air conditioners) is subject to EU legislation on F-gases. In practice, this means that tasks involving handling refrigerant - mainly connecting and evacuating the circuit, topping up refrigerant, and checking for leaks - should be carried out by a qualified technician with the appropriate certificate of professional competence. When ordering installation, it is entirely normal and legitimate to ask the company whether their technician has such a certificate - a reputable company will be able to answer without hesitation, possibly even showing the certificate directly.

In addition to professional competence, it is also worth checking a few practical matters with the company before placing an order:

Whether the price quote includes materials (pipes, insulation, consoles, additional refrigerant) or only labor - often an "attractive" low price can end up being higher due to separately charged materials.
What the warranty on the installation (not only on the product itself from the manufacturer) is and exactly what it covers.
Whether the company provides a certificate of leak test after installation - for some larger or commercial units, this documentation is even a legal requirement, but for a standard household air conditioner, it is a sign of a serious approach.
How long the company has been on the market and whether they have references - installing an air conditioner is a one-time investment for the next 10-15 years, so it is worth checking the company as thoroughly as the product itself.

Placement of the outdoor unit - what not to forget

The outdoor unit needs free space for air intake and exhaust; otherwise, its performance and efficiency will significantly decrease, regardless of how high-quality a model you have purchased. Common manufacturer recommendations for free space around the unit look roughly like this: at least 30 cm of free space on the sides, at least 60 cm of space in front of the unit (in the direction of the exhaust), and at least 15-30 cm from the house wall at the back. A unit placed tightly in a corner, between two walls, or under a low canopy without air circulation will work with significantly reduced efficiency in summer, as it draws in its own heated exhaust air.

Distance from windows is also important - the outdoor unit should be placed at least one meter away from the nearest openable window to prevent hot exhaust air from flowing directly inside during ventilation. The typical noise level of an outdoor unit at medium load ranges around 45 to 55 decibels (similar to a quiet conversation), which is why many municipalities recommend or even require a certain distance from the neighbor's property line in neighbor disputes - specific rules vary from one municipality to another, so it is worth checking local regulations in advance, not after a complaint has already arrived.

How long the installation takes and what to prepare in advance

A standard installation of one wall-mounted split air conditioner in an apartment or a single-family house takes approximately 4 to 8 hours under normal conditions, so it can usually be completed in one working day. In more complicated pipe routing, core drilling through thick walls, or when installing multiple indoor units on one outdoor unit (multi-split), the time may extend to two days.

Before the installation company arrives, it is worth considering a few things:

Pipe routing - the shortest and most direct route between the indoor and outdoor unit means less material, fewer additional charges, and better efficiency. Manufacturers of standard household units usually specify the maximum recommended pipe length in the range of 15 to 20 meters and a maximum vertical difference between units of up to 10 meters - beyond this range, the unit's performance and efficiency decrease, and additional refrigerant may need to be added.
Access to the outdoor unit installation site - if it is a higher floor without a balcony, ask the company in advance whether a platform is needed and who will provide it, so it doesn't come as a surprise on the installation day.
Condensate drainage - in summer, an air conditioner can produce several liters of condensed water per day; it is necessary to have a plan for where this water will drain (connection to the sewer, runoff along the facade, or possibly a condensate pump if the unit is not above a drain).
Free access to the room and the facade throughout the entire installation day - the company will need access both inside and outside, so plan accordingly.

Most common installation mistakes

Some mistakes can be spotted with the naked eye right after installation, while others become apparent only after months. Here is an overview of the most common ones:

The common denominator of most of these errors is the attempt to save time on steps that are not visible from the outside - vacuuming, condensate slope, thorough brazing of pipe connections. That is why when choosing an installation company, it does not pay off to decide based only on the lowest price; a price difference of 50-100 EUR between offers can ultimately mean the difference between a unit that lasts 15 years without problems and a unit that will have a compressor failure within two years due to a refrigerant leak.

Recommended models for installation

When choosing a specific model for installation, it pays off to select the capacity according to the room size - a lower capacity is sufficient for a small room, and an oversized unit in a small room will unnecessarily turn on and off in short cycles, which is not beneficial for it. Here are three proven models from the Vaillant brand in the ClimaVAIR pro range, which cover the common range of rooms from a smaller bedroom to a larger living room:

VAIB1-025WN outdoor and indoor unit with remote control - the smallest model in the range, suitable for smaller rooms and bedrooms up to about 25-30 m². The lower cooling capacity also means lower consumption when installed in a sufficiently large space, which is an ideal first step if you are solving air conditioning for just one or two rooms. Price from 527.00 EUR.

VAIB1-035WN outdoor and indoor unit with remote control - the middle power level, a common choice for a medium-sized living room or a combined living space with a kitchen. When installing this power level, it pays off to pay even more attention to the correct dimensioning of the pipe route, so that the unit delivers the declared performance even on the hottest days. Price from 561.00 EUR.

VAIB1-050WN outdoor and indoor unit with remote control - the most powerful of the three, suitable for larger rooms or spaces with high heat gains (large glazed areas, southern orientation). At this power level, the outdoor unit is usually a bit larger and heavier, which must be taken into account when choosing a support bracket and its anchoring into the façade. Price from 833.00 EUR.

Installation in an apartment and in a house - what is the difference

Installation in a house is usually simpler - the owner himself decides on the placement of the outdoor unit, the façade is usually more easily accessible from a ladder or directly from the ground, and there is no need to obtain consent from anyone else. A complication can be the greater distance between the room you want to cool and a suitable place on the façade (for example, a room on an upper floor facing a side where you do not want the outdoor unit to be visible from the street) - in that case, the pipe route is extended and so is the price.

In an apartment, especially in an apartment building with a shared façade, several additional steps are added. The first is the already mentioned consent from the owners' association or the building manager - in many buildings, the placement of an air conditioner on the façade is regulated by the building rules and without consent, the manager may request the removal of the unit even after some time has passed. The second is the passage of the pipe through the perimeter structure, which is often thicker in apartment buildings and sometimes insulated with a contact insulation system - in such cases, core drilling must be done carefully to avoid damaging the insulation around the hole and to prevent the formation of a thermal bridge. The third difference is the floor - higher floors without a balcony or a veranda often require work at height, which we wrote about in the section on installation costs above.

When installing an air conditioner in an apartment building, it pays off to think in advance about the aesthetic aspect - exactly where the outdoor unit will be visible from the street or from the neighbors, and whether there is a possibility to place it, for example, on the roof of the common areas instead of the façade (in some buildings, this is a common practice when solving air conditioning collectively for several apartments at once). Such a solution requires a longer pipe and thus a higher installation cost, but the result is visually cleaner and often also quieter for the apartment owner, since the unit is not right behind the window.

After installation - what to check and what to ask

Right after the installation is completed, it pays off to go through a few things together with the technician while he is still on site. Check whether the indoor unit makes any unusual noises during operation (bubbling, clicking, whistling), whether water actually drains from the condensate outlet during the test run, and whether the outdoor unit is securely fastened without visible vibration. Ask for a certificate of completed installation with the type and amount of refrigerant, date and technician's signature - you will need this certificate in case of a warranty claim and during regular service.

The warranty on the device itself is the responsibility of the manufacturer, while the warranty on the installation (i.e., the work) is the responsibility of the installation company - these are sometimes confused, but they are obligations of different parties. If a refrigerant leak caused by a poorly made connection appears within a year, it is a warranty claim for the installation with the company that performed the installation, not with the manufacturer of the unit.

Frequently asked questions

Can an air conditioner be installed in winter?

Yes, the installation itself is not limited to a particular season - the technician is able to install, connect, vacuum and test the unit even in winter. The only limitation is that the final test of the cooling capacity at low outdoor temperatures may not be entirely accurate, as most units have a specified minimum operating temperature range for cooling mode. If you plan to use the air conditioner for heating during the transitional period, this can be verified immediately, while the cooling function can be reliably tested only in warmer weather.

Do I need a building permit for air conditioner installation?

A standard installation of a split air conditioner in an apartment or a house usually does not require a building permit or a construction notification, as it does not involve any changes to the load-bearing structure. An exception may be apartment buildings with shared façades, where some owners' associations or management companies require consent for placing the outdoor unit on the façade - it pays off to check this directly with the building manager in advance, not on the day of installation.

Can I install the air conditioning myself if I'm handy?

The mechanical part - mounting the indoor unit, laying the piping, and securing the outdoor unit - can be handled by a skilled DIY enthusiast. The problem lies in the refrigerant part: vacuuming the circuit, checking for leaks, and possible refrigerant topping up require specialized tools (vacuum pump, manometer set) and experience working with F-gases. Without this step, the very risk we mentioned above arises - slow refrigerant leakage and compressor damage within the first few years of operation.

How long will a properly installed air conditioner last?

With quality installation and regular maintenance (filter cleaning, inspection every one or two years), the average lifespan of a home split air conditioner is around 12 to 15 years. Poor installation can significantly shorten this lifespan, especially if there is a slow refrigerant leak that goes unnoticed for a long time.

What if the outdoor unit cannot be placed on the wall facing the neighbor?

In such a case, it is advisable to look for an alternative location - a balcony, a roof with its own stand, or a wall facing another direction. If the wall facing the neighbor is the only realistic option, it is worth consulting the placement with the neighbor in advance and choosing the quietest model possible, or adding a noise barrier. This prevents potential disputes after installation, which are much harder to resolve than before it.

Is it worth addressing multiple rooms at once during installation?

If you already know you want to air condition two or more rooms, it makes sense to address them all at once - either in the form of a multi-split system (one outdoor unit, multiple indoor units), or at least by planning the cable and pipe routing in a way that allows for easy expansion later. Installing a second unit a year later is often more expensive than doing it at the same time as the first one, because the technician is already on site with the equipment, and part of the work (for example, modifying the electrical wiring) can be done simultaneously.

Do you have a question about this topic?

Having trouble deciding or dealing with a specific situation in your home? Write to us - we are happy to help.