Frequently Asked Questions About Air Conditioners – Selection, Installation, Operation, and Service
Common questions about air conditioners – selection, installation, operation and service
Air conditioning is now part of the standard equipment in modern homes, offices and businesses. Despite this, most people buy it once every ten to fifteen years – and it is therefore quite natural that they encounter dozens of questions when making a decision, to which they cannot find answers. Selecting the right device, understanding installation requirements, setting it up for efficient operation or knowing service obligations – these are all topics that repeat themselves over and over in practice. In this article, we have summarized the most common ones, and we answer them specifically and without unnecessary fluff.
If you are looking for answers to more specific subtopics, you will find separate articles in our Knowledge Centre such as What cooling capacity do I need – calculation based on area and room type, Step-by-step installation of an air conditioner – procedure and installation requirements or Split vs. multisplit air conditioning – which one is more cost-effective. Here we focus on cross-cutting questions – those that do not fall into one category, but customers ask them almost with every order.
Selecting an air conditioner – what you need to know before buying
What capacity do I really need?
This is the very first and most important question. A proven practice says that 70–100 W of cooling capacity is needed for every square meter of area for a standard room with a standard ceiling height (2.5–2.7 m) and average thermal load. So for a living room of 30 m², this comes to 2,100–3,000 W of cooling capacity, which corresponds to an air conditioner with a capacity of 2.5–3.5 kW.
However, this is only a rough estimate. In practice, you must take into account many more variables: the room's orientation to the cardinal directions (a southern and western façade can add 20–40 % thermal load), the area of glazing and its quality (single glazing vs. triple glazing), ceiling height (3 meters instead of 2.5 m increases the room volume by 20 %), the number of people in the room, the presence of thermal appliances (computers, servers, cooking appliances), the type of building and its insulation. A detailed calculation procedure can be found in the separate article What cooling capacity do I need, where we also discuss the professional calculation according to the standard.
Inverter or on/off – what is the difference and does it matter?
In today's time, this question is almost academic – on the market, inverter air conditioners clearly dominate, and it would be very difficult to buy anything else in regular retail. But customers still ask it, so we will explain: a classic air conditioner (on/off) runs the compressor either at full capacity or not at all. This means that the room is cooled until the set temperature is reached, then the air conditioner turns off, the temperature rises, and it turns on again. The result is temperature fluctuations and higher consumption when the compressor starts.
An inverter air conditioner regulates the compressor speed smoothly. After reaching the desired temperature, it does not disconnect the compressor, but slows it down to the minimum speed and only maintains the temperature. Energy savings are really 20–40 % compared to the on/off version. In addition, the compressor is less worn out, as there are no shocks when starting. An inverter is therefore not only more energy efficient, but also more reliable in terms of lifespan.
Split or multisplit – how to decide?
Split air conditioning = one outdoor unit, one indoor unit. Multisplit = one outdoor unit, two to five indoor units. It might seem that multisplit is always a better choice for a house with multiple rooms. In practice, it is not that simple.
Multisplit has one major drawback: if the outdoor unit fails, you will stop cooling (or heating) the whole house at once. Service costs for a larger outdoor unit are also higher. On the other hand, with two separate split systems, you can have one in operation even while the other is being serviced. Multisplit is more cost-effective mainly where there is no space for multiple outdoor units on the façade or roof. A more detailed comparison can be found in the article Split vs. multisplit air conditioning – which one is more cost-effective.
Installation of an air conditioner – what you need to know even before purchasing
Who can install an air conditioner in Slovakia?
This is one of the most common questions, where misunderstandings often occur. From the perspective of the refrigeration circuit, the installation of an air conditioner can only be carried out by a person with a valid certificate according to Regulation (EC) No 842/2006 or currently applicable Regulation (EU) No 517/2014 on fluorinated greenhouse gases (F-gases). This certificate is issued by the Slovak Chamber of Commerce or accredited certification bodies.
What this means in practice: you cannot fill the refrigerant yourself, you cannot manipulate the refrigerant circuits or open sealed valves. The mechanical part of the installation – the mounting for the indoor unit, the anchoring for the outdoor unit, the routing of cables – can be physically carried out by a builder or a skilled DIY enthusiast. But starting and filling with refrigerant must always be done by a certified technician. Violation of this rule can have legal consequences and also void the warranty from the manufacturer.
Where to place the indoor unit – what to pay attention to?
The most common mistake during installation is placing the indoor unit directly above a bed, sofa, or work area. A cold air stream blowing directly on a sleeping person for hours causes drafts and health issues. The correct position is where the air flows along the room and does not directly hit people, or where deflectors can direct it upwards/sideways.
Other guidelines for choosing a location:
- At least 15 cm of free space above the unit for air intake
- At least 2 meters above the floor for optimal distribution of cooled air
- The shortest possible route of refrigerant pipes to the outdoor unit (ideally up to 5 m, maximum according to the technical specifications of the device)
- The condensate pipe must have a slope towards the drain – at least 1.5 %, preferably more
- The wall must be load-bearing or a mounting frame for drywall must be used
Where to place the outdoor unit?
The outdoor unit needs free air access – on both the suction and exhaust sides. It must not be blocked by vegetation, fences, or other objects. Recommended minimum distances are 30 cm from the wall on the sides, 50 cm in front of the unit (in the direction of exhaust), and free space above it. Never place it in enclosed shafts without direct connection to the outside air.
Problems with noise and vibrations are another reason to think carefully about placement. An outdoor unit on a console under a bedroom window can disturb sleep at night, even if the device itself is quiet (35–45 dB). Vibrations are transferred through the console into the wall and then into the room. Anti-vibration pads and a proper console help significantly.
Operation of the air conditioner – efficiency and correct settings
What temperature is correct and how much does the air conditioner consume?
The most effective and at the same time health-acceptable temperature is 24–26 °C for cooling in summer. Every additional degree below 26 °C increases energy consumption by 6–8 %. An extreme is setting it to 18–20 °C in hot summer – the air conditioner has to work at full capacity, the difference between the outside and inside is 15+ °C, which is also unhealthy for the body.
Consumption depends mainly on the device's power, COP/EER coefficient (SEER for seasonal energy efficiency is stated today), and operating conditions. A modern inverter air conditioner with SEER 6–8 consumes 0.5–1.5 kWh for a room of 20 m² on an average summer day. For annual costs: if you operate the air conditioner for 8 hours a day, 90 days in the season, at an average consumption of 1 kWh and a price of 0.25 €/kWh, that is 180 €. A device with SEER 8 instead of SEER 4 will reduce consumption by half – saving about 90 € per year. An investment in a better device can pay off in 3–5 seasons.
Can I use the air conditioner for heating?
Yes, and that is one of the main selling points today. Modern inverter air conditioners are essentially air-to-air heat pumps – in summer they transfer heat from the interior to the outside, in winter the opposite. Most current devices operate reliably for heating down to -15 °C outside temperature, some premium models even at -25 °C. Efficiency for heating is indicated by the COP coefficient or the seasonal SCOP.
At an outside temperature of 7 °C, a typical inverter air conditioner has a COP of 3–4, which means that from 1 kWh of electrical energy it produces 3–4 kWh of heat. This is much more efficient than direct electric heating (COP=1) and comparable to a condensing gas boiler (at low gas prices). At a temperature of -10 °C, the COP drops to 1.5–2.5, which can still be economically interesting. Connecting the air conditioner to heating is discussed in the article Air conditioning in professional heating – combination with a heat pump and heating.
What to do if the air conditioner in summer cannot cool?
This is a common situation that customers face especially during heat waves. There can be several reasons:
- Undersized capacity – the air conditioner is simply too weak for the size of the space or its thermal load
- Dirty filter – the most common cause that customers overlook. A dirty filter can reduce performance by 30–40 %
- Dirty outdoor unit – condenser fins clogged with dust, poplar fluff, or insects
- Insufficient window shading – the air conditioner cools, but the sun through unshaded windows brings heat at the same rate
- Low refrigerant level – refrigerant leak reduces performance, requires professional service
- Extremely high outside temperatures above 40 °C – some devices have limitations in functionality at high outside temperatures
Service and maintenance – what and when to do
Cleaning filters – how often and how to do it?
The filter of the indoor unit is the first line of defense against dust and impurities. In normal home operation, it should be cleaned every 2–4 weeks during the active season. In dustier environments, with pets at home, or in year-round operation even more frequently.
The procedure is simple: open the cover of the indoor unit (usually it flips up), pull out the filter, clean it with a soft brush or vacuum, and if it is heavily dirty, rinse it with lukewarm water. Do not clean it with hot water, detergents with aggressive chemicals, or pressure water – the filter fins are delicate. The filter must be completely dry before inserting it back.
As for deeper maintenance – cleaning of the evaporator (heat exchanger in the indoor unit) and the condenser (in the outdoor unit) should be performed by a technician. At least once a year before the season is the minimum for proper functioning and device lifespan. More on this you can find in the article Maintenance and service of air conditioners – what to do regularly and what to leave to the professionals.
When is professional service necessary and what does it include?
Compulsory professional inspection depends on the amount of refrigerant in the system. According to the EU regulation on F-gases, it applies:
- Devices with CO₂ equivalent 5–50 tons (most home units): leak check at least once every 12 months
- Devices 50–500 tons CO₂ eq.: every 6 months
- Devices over 500 tons CO₂ eq.: every 3 months
Technical inspection before the season (1× per year) should include: checking the pressure in the refrigerant circuit, measuring electrical parameters, checking the tightness of connections, cleaning heat exchangers, checking the condensate drain, greasing moving parts, and a functional test of all modes. A typical price for such an inspection of a split air conditioner is 50–120 €, depending on the region and the scope of work.
Protection of the outdoor unit – accessories that extend its lifespan
The outdoor unit of an air conditioner is exposed to all weather conditions throughout the year. Direct rain, snow, frost, as well as flying insects, pollen, and wind carrying dust into the fins – all of this shortens the lifespan of the device and reduces its efficiency. For this purpose, special protective accessories are available.
For the IVAR.2.0 series air conditioners, the RAIN PROTECTION KIT for IVAR.2.0 air conditioners is available – a canopy that directs rainwater away from sensitive components of the outdoor unit. Protection against rain is especially important in installations where the unit is exposed to prevailing winds bringing rain directly into the exhaust or intake.
Equally practical is the INSECT PROTECTION KIT for IVAR.2.0 air conditioners. Insects – especially wasps, moths, and various types of beetles – are fond of nesting in the compartments of the outdoor unit. Nests block air flow and can cause short circuits in electrical components. Protective mesh is a simple but very effective way to prevent this. We have covered this topic in more detail in the article Protection of the outdoor unit against rain and insects – why and how to do it.
When replacing or repairing the cover of the outdoor unit, it is useful to know that for IVAR.2.0 models, a replacement Bottom cover for IVAR.2.0 is available, or for the more compact version, the Bottom cover IVAR.2.0 9HP MINI. A damaged cover is not just an aesthetic issue – it protects electrical wiring from water ingress and mechanical damage, so its replacement is worth doing without delay.
Common faults – how to recognize them and what to do
Air conditioner blows warm air when cooling
Most likely causes: dirty filter (most common!), low refrigerant level (leak), dirty outdoor unit, or compressor failure. First step – check and clean the filter. If that doesn’t help, call a technician. Refrigerant cannot be refilled or checked without certification and special equipment.
Air conditioner drips water from the indoor unit into the room
Condensate should drain through a pipe outside. If it drips into the room, the condensate drain is likely clogged (with algae, sludge, or insects) or the condensate tray is full. The drain can usually be cleaned by yourself – flush it with warm water or blow through the drain hose with a pump. If the problem persists, check the slope of the condensate hose – it must always slope downward, without siphons.
Noisy operation – vibrations or squeaking
New air conditioners are very quiet – indoor unit 19–30 dB(A), outdoor unit 45–55 dB(A). If one becomes significantly louder, it is a sign of a problem: loose brace, foreign object in the fan wheel, worn fan bearings, or loose screws on the cover. Some sounds (light cracking when starting/stopping) are normal – they are caused by expansion of plastic parts due to temperature changes.
More on recognizing faults can be found in a separate article Common air conditioner faults and how to recognize them.
Air conditioner and selection for professional use
Commercial and professional environments place different demands on air conditioners than a household. Longer daily operation (12–24 hours), higher number of people and heat sources, requirements for quiet operation, centralized control and monitoring, integration into BMS systems – these are parameters you don’t consider for home use, but in an office, hotel room, or server room, they are key.
For professional use, it is recommended to focus on devices with a higher SEER class (min. A++), the possibility of cascade connection or centralized control via a Wi-Fi module, low noise level (≤ 22 dB(A) for bedrooms, ≤ 35 dB(A) for office spaces), and availability of spare parts. A detailed guide on selection for professional environments can be found in the article How to choose an air conditioner for professional use – what to focus on.
Most frequently asked questions (FAQ)
Do I need a building permit for an air conditioner?
In most cases, you do not need a building permit for the installation of a standard split air conditioner in a house or apartment in Slovakia – it is considered maintenance work or a change in use that does not exceed the legally defined limits. Exceptions include protected buildings, listed buildings, apartment buildings where the facade is altered (in which case consent from the owner or a building permit may be required), or larger commercial installations. We always recommend consulting with the local building authority – it is free and will help you avoid potential complications.
How much does monthly operation of an air conditioner cost?
It depends on the power, intensity of use, and electricity price. Roughly: a 3.5 kW air conditioner with SEER 6 consumes about 420 kWh in 8 hours of daily operation over 90 days in the season. At a price of 0.22 €/kWh, this is about 92 € per year – roughly 30 € per month during the season. Winter operation as a heat pump is even more energy-efficient due to the high COP at mild frosts.
Can I let the air conditioner run through the night?
Yes, modern inverter air conditioners have a night (sleep) mode, where they automatically adjust settings for quiet and comfortable night operation – reduce noise, gradually increase the set temperature by 1–2 °C during the night, and eliminate direct air blowing. We recommend setting the temperature to 25–26 °C, not lower, and avoiding direct airflow onto the bed.
How long does an air conditioner last and when is it worth replacing?
With proper maintenance, a quality split air conditioner has a lifespan of 12–18 years, and some premium brands even 20 years. It is worth replacing when repairs start to exceed 40–50% of the price of a new unit, when the device uses refrigerant R22 (banned since 2015) or R410A (being gradually replaced), when its energy class significantly lags behind current models, and when annual savings would pay for a new device within 5 years.
Can air conditioning improve indoor air quality?
Partially yes – the filter in the indoor unit captures dust and partially pollen. Some models have ionizers, carbon filters or UV lamps for air disinfection. However, air conditioning is not a substitute for ventilation or a quality air purifier. On the contrary, a neglected filter can be a source of bacteria and mold – this is why regular cleaning is important not only for performance, but also for health.
Is it better to keep the air conditioner running all day or to switch it on only when needed?
For inverter air conditioners, it is more energy efficient to keep them running at a higher temperature (e.g. 26 °C all day) than to turn them off in the morning and cool a hot room down from 35 °C to 24 °C in the evening. Cooling a strongly heated space requires maximum performance for a longer period, which is more energy-intensive than continuously maintaining the temperature. Therefore, it is more economical to keep the air conditioner running in energy-saving mode during short absences (up to 4 hours).
Conclusion – what to take away
An air conditioner is a device where the investment in quality, correct selection and regular maintenance really pays off – through energy savings, longer lifespan and a healthier environment. The most common mistakes we see in practice: undersized capacity, incorrect placement of the indoor or outdoor unit, neglected filters and postponed service inspection. Each of these mistakes reduces performance and increases operating costs.
If you are considering buying a new air conditioner or dealing with a specific problem with your device, our Knowledge Center covers all key topics from calculating capacity, through installation and accessories, to combining with heating. And if you need specific spare parts or protective accessories for IVAR.2.0 air conditioners, an overview of available parts can be found in the article Accessories for IVAR.2.0 air conditioners – overview of parts and their function and directly in the air conditioning category on atria.sk.
Do you have a question on this topic?
Having trouble deciding or dealing with a specific situation in your household? Write to us – we are happy to help.