Step-by-step installation of air conditioning - procedure and installation requirements

We are still preparing products.

But you can look at other categories.

Installation of air conditioning step by step – procedure and installation requirements

The installation of an air conditioning unit may seem simple at first glance – an outdoor unit somewhere on the façade, an indoor unit on the wall, and a few pipes in between. In practice, it is a technical procedure that requires preparation, proper dimensioning, compliance with standards, and above all, professional knowledge. A mistake during installation can manifest immediately (leak of refrigerant, non-functional unit) or only after years (corrosion of pipes, compressor failure, reduced efficiency). This article will guide you through the entire process – from the planned location of the units through electrical connections and refrigerant charging to the final testing and handover to the customer.

If you are still considering which type of air conditioning to choose, we recommend reading our article Split vs. multisplit air conditioning – which one is more cost-effective, or What air conditioning capacity do I need – calculation based on area and room type. Here we will focus exclusively on the installation itself.

Who can install air conditioning – legal and professional framework

This question is fundamental and many investors do not even consider it. In Slovakia, the filling, emptying, and handling of fluorinated greenhouse gases (F-gases, which are common refrigerants such as R410A, R32 or R290) is regulated by European legislation – specifically Regulation (EU) No. 517/2014 (the so-called F-gas regulation). A technician performing these tasks must be certified, and the company must have a valid certificate for working with refrigerants. Without these certificates, any manipulation with refrigerant is illegal.

What does this mean in practice? If you are buying a split air conditioner and want to install it yourself (for example, systems with pre-charged lines intended for DIY installation), such products can only be sold with a sufficiently small amount of refrigerant that does not require topping up, and the installation must be carried out in a way that does not necessarily require handling of the refrigerant. In the vast majority of cases, however, professional installation of a split system requires a certified technician.

In addition to legislation on refrigerants, there is also a requirement for an electrician – air conditioners with a power exceeding a certain threshold require a separate electrical circuit, which must be carried out by a qualified electrician. At the same time, it is important to note that non-professional installation may result in the loss of the manufacturer's warranty.

Before the actual installation – what needs to be prepared and verified

Every successful installation begins with thorough preparation. From my own experience, I know that a large part of the problems during installation do not arise during the work itself, but precisely because some preparation step was skipped. Here is a list of what needs to be resolved before the installer arrives:

Selection of the location of the indoor unit – ideally on a wall without direct sunlight, at a height of 2.2 to 2.5 m above the floor, with at least 15 cm of free space on the sides and 10–20 cm above the unit. The airflow should not be directed directly at people during prolonged sitting.
Selection of the location of the outdoor unit – a well-accessible location with sufficient air flow around the compressor, protected from direct sunlight if possible, on a solid load-bearing structure (façade, console, roof). It must not be placed in a location where the exhaust air would bother neighbors or block escape routes.
Route for refrigerant piping and electrical cable – usually led through a wall opening (ø 60–80 mm), then along the façade or under plaster. You need to know what you will be passing through – insulation, brick, concrete, aerated concrete.
Maximum length and height difference of the piping – each manufacturer specifies the maximum length of the refrigerant piping and the maximum height difference between the units. Typically, it is 15–25 m in length and 10–15 m in height difference. If exceeded, it should be consulted with the manufacturer or refrigerant should be added.
Electrical preparation – air conditioners of 3.5 kW and higher usually require a separate 16A circuit with protection, or three-phase power supply for higher capacities.
Permissions – if you are modifying the façade of an apartment building or installing on a roof, you may need the building manager's consent, or possibly a building permit.

Installation of the outdoor unit – console, fastening, location

The outdoor unit (compressor) must be placed on a solid, statically reliable structure. Steel consoles anchored to the façade are most commonly used. The console must withstand the weight of the unit plus the vibrations during operation – for a standard 3.5 kW air conditioner, this is usually 60–100 kg. The anchoring points should be dimensioned with sufficient reserve, and anchoring into brick or aerated concrete requires anchors of the appropriate diameter and length (at least 100 mm into the load-bearing material).

It is recommended to place vibration dampers, such as rubber or spring mounts, under the outdoor unit – they reduce the transmission of noise to the building structure, which is especially important in apartment buildings or if the unit is located near windows of adjacent rooms. For thorough protection of the outdoor unit against atmospheric influences, a special RAIN PROTECTION KIT FOR AIR CONDITIONING IVAR.2.0 is also available, which protects the heat exchanger and electrical components from direct wetting during heavy rain or sleet.

When selecting the location for the outdoor unit, the following guidelines apply:

Minimum free space in front of the air outlet: 600 mm (otherwise air is drawn back and the compressor overheats).
Minimum free space behind the unit (intake): 200–300 mm from the wall.
Do not install above a path or sidewalk where dripping condensate could inconvenience pedestrians or freeze in winter.
When installing on upper floors, always ensure workers are protected against falling – scaffolding or platform.

If you plan to protect the outdoor unit from insects and dirt, which is especially important for ground floor and garden installations, the ANT-BUG KIT for IVAR.2.0 air conditioners is available. Insects in the condenser reduce the efficiency of heat exchange and can cause malfunctions. More information on this topic can be found in the article Protecting the outdoor unit from rain and insects – why and how to do it.

Installation of the indoor unit – mounting, height, orientation

The indoor (wall-mounted) unit is attached to a steel mounting plate, which is screwed directly into the wall. This step requires precision – the plate must be horizontal (maximum deviation 1–2 mm/m), because a tilted unit will have improper condensate drainage and may leak into the interior instead of into the drain hose.

Steps for installing the indoor unit:

Place the mounting plate on the wall, mark the position of the anchors and the pipe hole (ø 60–80 mm), usually in the lower left or lower right corner of the plate.
Drill holes for anchoring (minimum 4 points) and the pipe hole with a slight slope outward (3–5°), so that the condensate hose naturally drains water outside.
Mount the mounting plate on the wall and check the horizontal alignment with a spirit level.
Put on the cover strip (if used) and thread the pipes through the hole – refrigerant copper pipes, electrical cables, and the condensate hose.
Hang the indoor unit on the mounting plate – it clicks into place and is secured with a safety lock.

If you are installing the IVAR.2.0 unit and need to aesthetically finish the lower part of the unit cover, you can use the Bottom cover for IVAR.2.0, or for more compact models, the Bottom cover – IVAR.2.0 9HP MINI. These covers protect the lower cable and pipe routing from mechanical damage and improve the overall aesthetic appearance of the installation.

Refrigerant piping – bending, insulation and joining

The refrigerant piping is the heart of the entire system. ACR copper pipes of special quality are used – usually ø 6.35 mm (1/4") for the liquid line and ø 9.52 mm (3/8") or ø 12.7 mm (1/2") for the gas line, with the exact dimensions depending on the model and performance of the air conditioner. Each manufacturer specifies the exact dimensions for individual performance classes.

The copper pipes must be:

Clean from the inside – any moisture or dirt can damage the compressor or create acid in the circuit. Therefore, the pipes are stored sealed and cut only with a pipe cutter (not with a saw – sawdust would contaminate the inside).
Bent without kinks – the minimum bend radius is usually 30–40 mm. Kinks in the pipe narrow the flow and cause cavitation. A manual or hydraulic pipe bender is used for bending.
Connected with flared fittings (flare) – the ends of the pipes are flared with special tools (flare tool) and tightened with nuts on the unit valves. The flared end must be even, without cracks and with an exact angle of 45°.
Insulated – each pipe must be wrapped with insulation made of expanded polyethylene or EPDM (minimum thickness 9–13 mm). Both pipes can be insulated together or separately, with UV-resistant insulation being suitable for the exterior.

After laying the entire routing and connecting both units, the following is performed:

Pressure test – nitrogen is injected into the circuit at a pressure of 30–40 bar and the circuit is left under pressure for at least 24 hours. If the pressure does not drop, the circuit is tight.
Vacuuming – using a vacuum pump, air and moisture are removed from the circuit until at least –1 bar vacuum is achieved (deep vacuum 500 microns or less). Insufficient vacuuming is one of the most common causes of premature compressor failure.
Charging with refrigerant – refrigerant is released into the circuit via the service valve on the outdoor unit. If the routing is longer than the standard length specified by the manufacturer, refrigerant must be added according to the prescribed value per meter of additional routing (typically 20–30 g/m).

Electrical connection – power supply, control and communication

A split air conditioner usually has two electrical parts: power supply for the outdoor unit (directly from the electrical panel) and a communication cable between the outdoor and indoor unit. Some models power the indoor unit from the outdoor unit via the communication cable, while others require a separate power supply for each unit – always check the wiring diagram of the specific model.

Basic rules for air conditioner electrical connection:

A separate electrical circuit with a 16A circuit breaker (single-phase) or 3×16A (three-phase) – according to the power and model.
Earthing (protective conductor PE) – mandatory for all air conditioners.
Cross-section of the power cable: at least 2.5 mm² (Cu) for single-phase models up to 3.5 kW, 4 mm² for more powerful units.
Cross-section of the communication cable: typically 4×0.75 mm² (shielded or unshielded according to the manufacturer).
Installation of a disconnect switch (service disconnector) directly at the outdoor unit – required by the EN 60335 and VDE standards.

A certified electrician must confirm the electrical connection with a protocol – this document is important not only for the warranty, but also for any insurance claims.

Condensate pipe – drainage, slope, trap

The condensate pipe drains water from the indoor heat exchanger (condensation of humidity from the interior during cooling). Its correct connection and routing are crucial – incorrect condensate drainage causes the unit to leak into the interior, which is one of the most common complaints after installation.

Guidelines for condensate drainage:

Minimum slope of the pipe: 1 cm per meter of length (ideally 2–3 cm/m).
The pipe must not have areas where water can collect (upward bends, trap-like sections without an intentional trap).
The pipe outlet must point to a location where dripping is not a problem – sewer inlet, garden area, gutter. It must not point to a sidewalk or to a neighbor's property.
In the case of connection to the sewer, a trap is recommended to prevent sewer odors from entering the unit.
In colder facades or when passing through unheated areas, condensate may freeze in winter – the solution is an electric heating cable in the pipe.

Starting, setting and testing the air conditioner after installation

After completing all mechanical and electrical work, the phase of functional testing begins. Do not rush – each step has its logic and skipping it may mean that a problem remains undetected and will only appear later under full load.

Procedure for starting and testing:

Pre-power check – visual inspection of all connections, re-check the correctness of cable connections, check the tightness of service valves.
First power-on in cooling mode – set the lowest temperature (16–18°C) and monitor the unit's behavior. The outdoor unit should start up within 3–5 minutes.
Measuring temperatures and pressures – using a manifold (pressure gauge set), measure suction and discharge pressure, which are compared with service values for the given refrigerant at the current outdoor temperature. The pressure must correspond to the refrigerant saturation curve.
Measuring superheat and subcooling – delta T between suction gas and saturation temperature (superheating) should be 5–8 K, subcooling 5–10 K. Deviations indicate incorrect refrigerant charge.
Testing heating mode – in inverse (heat pump mode), set the maximum temperature and monitor whether the outdoor unit correctly defrosts (defrost cycle).
Noise and vibration check – listen for unusual sounds, knocking, whistling. Check whether tightening of the piping causes vibration transmission to the wall.
Setting up the remote control and WiFi module – set the desired parameters, test all operating modes (COOL, HEAT, DRY, FAN, AUTO), program the timer if available.
Installation protocol and handover – hand over the service protocol to the customer with the measured pressure values, type and amount of refrigerant used, installation date and technician's signature.

Typical installation errors of air conditioners – from real practice

Over the years of practice, the same errors repeat. I mention them here not only so you know what to watch out for, but also so you know what to ask when choosing an installation company and what to check.

Insufficient evacuation – the technician evacuates only 10–15 minutes instead of 30–60 minutes, or evacuation is not performed at all. Moisture in the circuit causes an acidic environment that destroys the compressor. It manifests itself after 1–2 years of operation.
Poor flaring (flare) – cracks or uneven flaring cause refrigerant leaks, which may not appear immediately, but gradually cause a drop in performance and eventually compressor stoppage.
Insufficient pipe insulation – especially on suction pipes (larger diameter), condensation of moisture occurs if not properly insulated. The result is a wet wall, corrosion and performance losses.
Incorrect position of the outdoor unit – too close to the wall, in a corner, where there is not enough airflow. The compressor overheats, pressure in the circuit increases and lifespan is reduced.
Condensate shortcut – the condensate pipe is not connected or is sloped in the wrong direction. Water runs down the wall, behind the unit or into the electrical system.
Maximum pipe length not respected – with too long a pipe without refrigerant addition, the system runs with insufficient charge and the undersized compressor is overloaded.
Missing service protocol – the customer does not receive a document confirming the installation, the refrigerant used and the measured values. Without a protocol, the installer's responsibility cannot be proven.

Typical Installation Schedule – What to Expect

For a standard apartment installation (1 indoor + 1 outdoor unit, 5–8 m piping), a realistic schedule is as follows:

Preparation and measurement (30–60 min): measuring the location, marking drilling points, preparing tools and materials.
Drilling the wall hole and mounting the bracket (30–60 min): depends on the wall material (concrete vs. brick) and access to the façade.
Mounting the indoor and outdoor unit (60–90 min): securing, threading the pipes, electrical connection.
Pressure test (24 hours): most installers perform the test for several hours, the correct procedure is 24 hours.
Vacuuming (30–60 min): at least 30 minutes with a good vacuum pump, longer for longer piping.
Startup and testing (30–60 min): pressure measurement, checking all functions, setting up the control.
Cleanup and handover (15–30 min): cleaning the work area, filling in the protocol, instructing the customer.

The overall pressure test usually requires two visits (one day for drilling and mounting + another day for vacuuming and startup) or one long working day with pressure holding overnight. Installations that finish everything in 2–3 hours without pressure testing are rushed and riskier.

Protection and Accessories for Long-Lasting Installation

After completing the installation, it is advisable to think about long-term protection. The outdoor unit is exposed to weather conditions all year round – UV radiation, rain, snow, insects, and mechanical damage. A few practical recommendations:

Installation of rain protection kit – protects the heat exchanger from direct wetting during heavy rain and reduces the risk of fin corrosion.
Installation of insect protection kit – especially important for ground-level or garden installations, where insects naturally seek heat and shelter. Clogged fins reduce performance and increase energy consumption.
Regular inspection of the bracket and anchoring points – at least once a year, ideally before the summer season.
Cleaning of the indoor unit filters – every 2–4 weeks with intensive use.
Professional service inspection once every 2 years – pressure measurement, cleaning of heat exchangers, electrical inspection.

A comprehensive overview of the full range of accessories can be found in the article Accessories for IVAR.2.0 Air Conditioners – Overview of Parts and Their Functions. Regular maintenance is discussed in detail in the article Air Conditioner Maintenance and Service – What to Do Regularly and What to Leave to a Professional.

Air Conditioner as Part of a Comprehensive Heating System

More and more customers are using inverter split air conditioners not only for cooling but also for heating during transitional periods (autumn, spring), or as a primary heat source in well-insulated buildings. Modern air-source heat pumps can heat efficiently even at outside temperatures of -15°C to -25°C, with a COP (Coefficient of Performance) of 2.5 to 4.5 even in winter conditions.

When planning a combination of an air conditioner with an existing heating system, it is important to consider: the capacity of the air conditioner relative to the building's heat loss, compatibility of the control with the existing thermostat, and backup in extreme cold. We discuss this topic in detail in the article Air Conditioner in Professional Heating – Combining with Heat Pump and Heating.

Most Frequently Asked Questions (FAQ)

Can I install the air conditioner myself if I am handy?

You can perform the mechanical part of the installation (mounting the bracket, securing the indoor unit, running the pipes) yourself if you have experience with masonry and plumbing work. However, work with refrigerant – pressure testing, vacuuming, and charging the refrigerant – must be performed by a certified technician with a valid F-gas certificate. Without it, handling refrigerant is illegal, and the customer risks a fine and loss of warranty.

How long does the installation of a standard split air conditioner take?

For a standard installation (one indoor + one outdoor unit, up to 8 m of piping, accessible façade), expect a 1–2 day process. The first day involves mechanical installation and electrical connection, the second day (or after 24 hours of pressure testing) vacuuming, charging, and testing. Installations that take 2–3 hours are possible, but usually mean skipping the pressure test.

How far apart can the outdoor and indoor units be?

It depends on the specific model, but most standard split air conditioners allow a pipe length of 15–25 m and a height difference of 10–15 m. When exceeding the standard length (usually 5–7 m stated by the manufacturer), you need to add refrigerant – typically 20–30 g per extra meter. With longer piping, the system's performance and efficiency decrease, so it is always better to keep the piping as short as possible.

What to do if the air conditioner does not heat or cool after installation?

The most common cause is insufficient refrigerant charge – either it has evaporated due to a leak (a loose connection), or it was not added in the case of longer piping. Call a certified technician who will measure the pressures in the system and determine whether there is enough refrigerant and where a possible leak might be. Do not add refrigerant "by eye" without measurement – an excess of refrigerant can damage the compressor just as much as a shortage. More about faults can be found in the article Common Air Conditioner Faults and How to Recognize Them.

Is a building permit required for air conditioner installation?

For standard apartment installations in a single-family house, usually not. However, if you are installing on the façade of an apartment building, you need the consent of the owners' association (SVB) or the management company. In historical buildings or protected zones (monumental reservation, NNR), you may need an opinion from the heritage office. In some municipalities, local regulations apply – check in advance at the building office.

Do I need to service the air conditioner every winter?

Annual service is not mandatory, but it is recommended every 2 years or annually in the case of intensive year-round operation (heat pump as the primary heat source). The minimum maintenance you can do yourself is cleaning the indoor unit filters (every 2–4 weeks during operation) and a visual inspection of the outdoor unit (cleanliness of the fins, undamaged insulation). A professional technician will check the refrigerant pressures, electrical condition, and cleanliness of the heat exchangers. A detailed procedure can be found in the article Air Conditioner Maintenance and Service – What to Do Regularly and What to Leave to a Professional.

Conclusion – Air Conditioner Installation Deserves a Professional Approach

Proper air conditioner installation is not just about drilling holes and running pipes. It is a complex technical procedure, where each detail affects the performance, reliability, and lifespan of the equipment. An investment in a quality installation performed by a certified technician pays off – the system operates more efficiently, consumes less energy, breaks down less, and lasts longer. On the contrary, cutting costs on installation leads to problems that will be much more expensive to fix later.

If you are planning to buy an air conditioner and have not yet decided on a specific model, we recommend the article How to Choose an Air Conditioner for Professional Use – What to Focus On and Common Questions About Air Conditioners – Selection, Installation, Operation, and Service. If you have specific questions about installation or accessories for a particular model, our team is happy to help.

Do you have a question about this topic?

Struggling to make a decision or dealing with a specific situation in your home? Write to us – we are happy to help.