Air Conditioner Installation - What You Need to Know

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Air conditioning is only as good as how well it is installed. Two completely identical units, one professionally installed according to the manufacturer's instructions and the other installed "for half the price from the neighbor," can differ in cooling efficiency by up to 20-30% in practice, even if nothing appears to be wrong at first glance. The problem only becomes apparent after one to two years, when the refrigerant slowly leaks through a loose connection, the compressor becomes overloaded, and the unit, which was supposed to last 12-15 years, fails after just five. In this article, we will explore what air conditioning installation actually involves, what most affects its cost and complexity, what to look 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 usually in good condition from the factory; quality control is at a high level for reputable brands. The weak link in the chain is almost always the installation: the quality of the pipe connections, the thoroughness of system evacuation, proper refrigerant charge, and whether the outdoor unit is placed in a location that allows sufficient air exchange.

A leaky pipe connection does not immediately show itself from the outside. The refrigerant leaks slowly, and the unit initially cools almost normally, just a little 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 selection of an installation company and the monitoring of the installation process the same attention as 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 an apartment or a single-family house 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—evacuation and pressure test—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 skipped for just a few minutes or completely omitted, 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 evacuation 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, on a brick or concrete wall, on the ground floor or an easily accessible floor—typically ranges from 150 to 250 euros. Additional charges are added according to 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)—an 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 needed (high-rise apartments, complex 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 routes), the cost can be even higher—in such cases, it is always better to request a specific quote after an on-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 (such as refrigerants R32, R410A, and similar ones commonly used in household air conditioners) is subject to European legislation on F-gases. In practice, this means that work involving refrigerant manipulation - mainly connecting and vacuuming the circuit, adding refrigerant, and leak checking - should be carried out by a qualified technician with the appropriate certificate of professional competence. When ordering installation, it is completely normal and legitimate to ask the company whether their technician has such a certificate - a reputable company will be able to answer this without hesitation and may even show you 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 actually turn out to be higher due to separately charged materials.
What the warranty on the installation (not only on the product itself from the manufacturer) is and what exactly 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 you would 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 the model you bought is. Common manufacturer recommendations for free space around the unit look something 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 air exhaust), and at least 15-30 cm of clearance 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 hot exhaust air.

Distance from windows is also important - it is advisable to place the outdoor unit 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 is 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 municipality to municipality, so it is worth checking local regulations in advance, not after a complaint has already been made.

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 is usually possible to complete it 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 can be extended to two days.

Before the installation company arrives, it is worth thinking about 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 recommend a maximum pipe length 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 will be needed and who will provide it, so you are not surprised on the day of installation.
Condensate drainage - in summer, an air conditioner can produce several liters of condensed water per day; you need to have thought out where this water will drain (connection to the sewer, drainage along the facade, or possibly a condensate pump if the unit is not above the sewer).
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 only become apparent after several 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 in two years due to a refrigerant leak.

Recommended models for installation

When choosing a specific model for installation, it pays to choose the capacity according to the room size - a lower capacity is sufficient for a small room, and an oversized unit in a small room often turns 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. A 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 - a medium 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

In a house, installation 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 get approval from anyone else. A complication can be a greater distance between the room you want to cool and a suitable place on the façade (for example, a room on an upper floor oriented on the side where you do not want the outdoor unit to be visible from the street) - in such a 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 approval of the owners' association or the manager - in many buildings, the placement of an air conditioner on the façade is regulated by the building regulations and without approval, the manager may request the removal of the unit even after a period of time. The second is the passage of the pipe through the perimeter structure, which in apartment buildings is often thicker and sometimes insulated with a contact insulation system - in such a case, core drilling must be done carefully so that the insulation around the hole is not damaged and a thermal bridge does not form. The third difference is the floor - higher floors without a balcony or a loggia often require work at height, about which we wrote in the section on the cost of installation above.

When installing an air conditioner in an apartment building, it pays 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 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 himself, 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 to go through a few things together with the technician while he is still on site. Check whether the indoor unit makes unusual noises (bubbling, clicking, whistling) during operation, whether water actually drains from the condensate outlet during the test run, and whether the outdoor unit is firmly anchored without visible vibration. Ask for a certificate of completed installation with the type and amount of refrigerant, the date, and the 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 two things 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.

Common 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 defined 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 approval for placing the outdoor unit on the façade - it pays 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 am 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: evacuating the circuit, checking for leaks, and possibly topping up the refrigerant require specialized tools (a vacuum pump, a set of manometers) as well as experience working with F-gases. Without this step, the very risk we mentioned above arises - a slow refrigerant leak 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 typical lifespan of a home split air conditioner is around 12 to 15 years. Poor installation can significantly shorten this lifespan, especially if a slow refrigerant leak occurs and goes unnoticed for a long time.

What if the outdoor unit cannot be installed 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 even adding a noise barrier. This prevents potential disputes after installation, which are much harder to resolve than before it.

Is it worth handling multiple rooms at once during installation?

If you already know you want to air condition two or more rooms, it is worth handling 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 installing it together with the first one, as 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.