Too cold, too warm or too high humidity – the temperature and humidity in our rooms contribute essentially to our overall well-being.
Just a few days of sun can heat up your apartment and increase the humidity. Air conditioning can help you regulate the temperatures in your own home and thus increase your well-being.
In our air conditioning test 2021, we have summarized all important information on the topic. In addition, we have built-in many tips and tricks that can help you find the perfect air conditioning for you.
Air Conditioner Buying Guide: Questions to deal with before you buy an air conditioner
Air conditioning is in most cases an acquisition that has been in use with you for many years. In this section, we’ll tell you about the most important questions you should ask yourself before you buy air conditioning.
How does the air conditioning work and what are its tasks?
Air conditioning is used for heating, humidifying, cooling and dehumidification, as well as for renewing and cleaning the air. Otherwise, it is only a partial air conditioning system or ventilation.
Air conditioning can be of great use, especially in summer.
Tasks of air conditioning
Room air conditioning has the task of transporting energy from one place to another. It will be handed over there. An air conditioner does this by removing heat from the room air, transporting it outwards via a condenser and the refrigeration circuit and dissipating it there again.
Air conditioners are designed to create an optimal indoor climate. This should happen independently of external and internal influences.
Air conditioning is therefore used to treat the air. The following systems are used:
- Air-only climate algae
- Air-water air conditioning systems
- Air-refrigerant air conditioning systems
- Water-only air conditioning systems
The air- or water-carrying versions use surface heating systems and surface cooling systems that have chambers filled with water.
In the central components of these air conditioning systems, the supplied air is air-conditioned. This is done by tempering, humidifying, dehumidifying and filtering. It is then delivered to the interior of the house. The systems offer a high degree of flexibility with regard to the individual air conditioning of rooms.
Air-only system rules are suitable for particularly large rooms and where surface systems can interfere with water, for example in theatres or conference rooms. The air conditioning is carried out completely via the supplied air.
Decentralized air refrigerant systems combine a splitting system with a KSV, a single-channel system with constant supply air. It is composed on an internal evaporator that removes heat from the room and a condenser outside, which releases the heat again.
A splitting system is suitable for cooling and dehumidification (or in heat pump operation for heating) a room. The outdoor air supply is provided via the KVS system.
- First, the refrigerant is sucked in by a compressor in a gaseous state. It compresses the refrigerant and the temperature increases immensely.
- The refrigerant is now hot and reaches the condenser or capacitor by means of a compressor. It is then cooled by a fan through the outside air. The refrigerant then condenses and becomes liquid.
- The now liquid refrigerant is exposed to high pressure and is now returned to the internal evaporator via the expansion valve.
- A fan announces the warm room air. The liquid refrigerant evaporates, for which energy is needed. This occurs when the heat is removed from the room air. As a result, it cools down and can be released back into the room.
- Due to the evaporation, the refrigerant is gaseous again, gets back into the compressor and is compacted there again. It cannot be lost throughout the process because the cooling circuit is hermetically sealed off. However, water vapour condenses on the evaporator. A pipeline is required for the discharge.
If the air conditioning is to be heated, the process turns around: the outside air is removed from the air and released into the room.
What are the advantages and disadvantages of air conditioning systems compared to conventional ventilation systems?
Central ventilation systems prepare the room air in an energy-efficient manner. They meet all requirements for the quality and temperature of the air, the humidity, the volume in operation and the freedom to move. That is why they have proved their worth.
- Quiet operation
- Energy efficiency
- Powerful heat recovery systems
- Without regular maintenance, germs are produced
- Cold shock without regulation
- High energy costs depending on the duration and performance of use
Central ventilation systems are usually installed on the off-traffic side of the building close to the ground and protected from wind and rain. They transport warm outdoor air to the building in winter and cool in summer.
Due to their size, components with high offsets can be used. Powerful heat recovery systems also increase energy efficiency.
Full-fledged air conditioners have five functions that other air systems do not combine:
- Renewing and cleaning the air
However, there is often talk of air conditioning when it performs the cooling function.
Are there also mobile air conditioning systems?
Air conditioners or air conditioners can also be mobile. We’ll explain how these devices work later. In most cases, mobile air conditioners are suitable for apartments and individual rooms because they do not take up as much space and do not require a large installation.
How much electricity does air conditioning consume and how efficient is it?
The energy efficiency class indicates how effectively an air conditioner converts electricity into the cold. The less electricity is needed to achieve a certain cooling system, the more economical the air conditioner works.
Energy efficiency is classified in A to G, with Class A devices being particularly energy-saving. The best air conditioners in this respect are class A+++. However, they are quite expensive to purchase. Another indication of efficiency is the COP value. Air conditioning systems of energy efficiency class A are at least 3.2. This figure states that at least 3.2 kilowatts of cooling capacity are generated from one kilowatt of electrical power.
Air conditioners are known as power eaters, but by specifying the efficiency, also called energy efficiency class, electricity providers and duration of use, the cost can be estimated relatively well.
A mobile air conditioning system consumes about 0.24 euros per hour, a split air conditioning system about 0.17 euros per hour and a heat pump about 0.90 euros per hour.
Who are air conditioners suitable for?
Air coolers are suitable for all people who want a pleasant indoor climate in the warm and hot season. Properly installed and dimensioned air conditioning contributes to overall health.
Air conditioners use different filters. This cleans the room air at the same time. Because they regulate the temperature and humidity in the room, they contribute to the general well-being. The room temperature, which most people perceive as pleasant, is 22 to 24 oC, and the relative humidity is 45-50 per cent. However, this value varies depending on the room, for example, the ideal temperature in the bedroom is lower, which is why many people buy air conditioning for their bedroom.
The warm air in summer contains a lot of moisture. The human body finds warm air with high humidity very unpleasant. By air-conditioning of a room, the air is dehumidified and reduced to a pleasant temperature.
What are the alternatives to air conditioning?
There are some alternatives to air conditioning, some of which are also cheaper to purchase and certainly a good way to cool a room at short notice. These include mobile air conditioners without hoses, fans and central ventilation systems. However, it remains to be said that no comparable effect can be achieved.A mobile air conditioner without exhaust air hose is often not the same as a mobile air conditioning system.
The air conditioner cools by distributing the cooled air using water, cooling pads, ice cubes, etc. Real air conditioning, on the other hand, deprives the room air of heat through a special cooling process using coolant.
Where is air conditioning most commonly used?
Air conditioning systems are mostly used where we spend most of our time: at work. Air conditioning is most often used in large plants. Especially central air conditioning systems, but also ceiling and wall cooling systems are already taken into account in the construction planning. Especially in the workplace, it is important to achieve a pleasant indoor climate. There are also many possibilities for private use. Most of the time, a decentralized air conditioning system is used to cool down, for example by monoblock units, window air conditioners or monoblock units without exhaust air hose.
But also for private use, there are ceiling and wall cooling systems, which can be installed centrally with the planning of construction.
Especially in rooms where you stay and work very often, there should be a pleasant indoor climate, which in turn has a positive effect on health.
Do I need cooling for an entire building, for a room, for the caravan/caravan/camper?
Before purchasing, you should definitely consider how many rooms should be cooled and, above all, the duration of the use of the air conditioning. When planning your purchase, you should consider whether a fixed air conditioner, which in turn involves more costs and effort or a more mobile version is sufficient for your needs.
If you have thought through these points well, we recommend that you obtain information in specialist stores, retailers and online shops for this type of air conditioning and compare them.
Decision: What types of air conditioners are there and which one is right for you?
Air conditioning systems vary depending on the working method and installation location. For example, there are central and decentralized systems as well as air-only, air-water, air-refrigerant and water-only air conditioning systems in terms of ventilation function.
However, in practice and in language, the individual systems are often not exactly separate.
In principle, air conditioning systems can be divided into two broad categories – central and decentralized air conditioning systems – and according to their design:
- Central building air conditioning
- Decentralized air conditioning
- Split air conditioning
- Monoblock air conditioning
- Inverter air conditioning
- Window air conditioners
Central building air conditioning
In a central building air conditioning system, a single device combines the function of cooling and air treatment. For this purpose, all rooms are connected to each other via ventilation ducts. They are used for heat exchange.
Some air conditioners can not only cool but also heat. (Image source: 123rf.com / Andriy Popov)
In order to realize this, central climate adaptations are usually already planned when it comes to the construction of new houses, which should have such a system.
- Energy-efficient than decentralised air conditioners
- Individual controllability of the rooms
- Lower noise nuisance than with decentralized systems due to central system parts and soundproofing flaps
- Better air exchange
- The high cost of purchase throughout the building
- Increased maintenance for hygienic operation
- Subsequent installation problematic
Decentralized air conditioning
Decentralized air conditioning systems such as split systems and fan convectors treat, convey, filter and temper the air in the room. Their design is similar to that of indoor air conditioners, but both systems differ.
- Installation later easier possible
- cheaper to purchase than central air conditioning systems
- Mobility possible if necessary
- multiple air conditioning systems for several rooms
- less energy efficient than central air conditioning systems
Decentralized air conditioning systems also require multiple air conditioners to cool multiple rooms. They are suitable for use in already completed houses.
The split air conditioning system
Split air conditioners consist of two parts that are connected by pipelines. The refrigerant flows through them.
- Through 2 parts system, a louder component can be moved to the outside, quieter to the interior of the room
- High cooling efficiency
- Fewer allergens
- A good solution to the heat-dissipating problem
- More power
- Major structural measures necessary / pipelines through the wall
- Direct air conditioning of a room
- Striking on the exterior facade
- More expensive in acquisition and operation
The noisy part of the split air conditioning system is located outside the house. The warm air is blown out of the room. The quieter part, on the other hand, is installed in the room, where it refrigerates and cools the air.
However, only one room can be cooled. Otherwise, you will need to buy a multi-split air conditioner that has multiple interior parts.
Who is a split air conditioner suitable for?
The advantages of split air conditioners are obvious. The low volume, the higher cooling efficiency and the associated lower electricity costs make split air conditioners the ideal choice for those who want to retrofit air conditioning in individual rooms in their home.
Inverter air conditioner
An inverter air conditioner is a better split air conditioning system. Normal split air conditioners only have a simple thermostat for monitoring room temperature. When the selected temperature is reached, the device turns off. If it is exceeded, it turns on again.
- Refrigeration capacity infinitely variable
- Keeping even room temperature
- Energy efficient
- Noise level lower
- More expensive to buy
- Pipelines between the outer part and the inner part must be permanently laid through the house wall
- Higher energy consumption with a long-term constant high cooling performance
Devices with inverter technology are controlled more gently. The cooling capacity is infinitely variable, i.e. the device slowly shuts down and only gradually picks up speed. The room temperature can thus be kept even more evenly. In addition, devices with inverter technology consume less energy.
However, due to the higher technical effort, they are more expensive. The built-in inverter control regulates the speed of the compressor and adjusts it to the current power requirement.
This continuous operation improves efficiency, which can lead to energy savings of up to 30 to 60 per cent.
Inverter split air conditioning systems are therefore particularly economical and recommended for multi-split applications. The noise level is also lower.
Central air conditioners are very effective. However, they are very difficult to retrofit afterwards. Therefore, inverter split air conditioning systems and monoblock air conditioners are recommended.
Who are inverter air conditioners suitable for?
Inverter air conditioners are the best choice for anyone who wants to air-conditioning individual rooms in the house afterwards and save operating costs in the long run.
There are many different types of air conditioners, all of which have different advantages and disadvantages. (Image source: 123rf.com / SORAPONG CHAIPANYA)
The ideal application scenario for inverter split air conditioners are rooms that should not be overly cooled over a long period of time. In this situation, the advantages of the devices come fully to bear.
Monoblock air conditioning system with an exhaust air hose
Monoblock devices are the classic mobile air conditioners that are often found in DIY stores.
The term monoblock air conditioner comes from the fact that all components of the air conditioning system are combined into a single device, typically in block form.
The heat absorbed from the room air is transported outwards in this type of air conditioner via an exhaust air hose. This exhaust air hose must be guided outwards through a window gap.
- Compact / low space consumption
- Low acquisition costs
- Adaptation to rooms to be cooled possibly
- Noise level
- Lower energy efficiency due to exhaust hose placed through windows – heat can penetrate the room
- High power consumption / not suitable for continuous use
Who is a monoblock air conditioner suitable for?
Mobile air conditioners in the form of monoblock devices are not suitable for continuous operation over a longer period of time due to their low cooling efficiency, the relatively high electricity costs and the volume not to be underestimated.
Due to the comparatively low purchase price and the high mobility, we, therefore, recommend monoblock air conditioners, especially for heat-stricken people who only want to cool down different rooms temporarily with a mobile device.
Window air conditioners
On the other hand, there are also compact air conditioners, which contain all components in a housing and are either installed directly into a wall or a window or are installed as a mobile device in the room.
Window air conditioners are often used in apartments, motels and small apartments. They are simply integrated into walls or windows and are thus directly connected to the outside world.
- The problem of heat dissipation solved by direct application in-wall and/or window
- Less power consumption than portable monoblock devices
- Less noise nuisance than an air conditioner with an exhaust air hose
- Unsuitable for cooling multiple rooms at once
- Wall breakthrough (for window air conditioners)
Due to the installation on the wall, the problem of heat dissipation without exhaust air hose is solved and thus one of the main disadvantages of mobile air conditioning units is eliminated. The cooling efficiency is therefore significantly higher and air conditioners mounted on the wall require less electricity as a result.
The biggest advantage of air conditioning units without exhaust hose/window air conditioners is at the same time the biggest disadvantage because a wall breakthrough is necessary for installation.
Depending on the individual conditions on-site, however, it may be that no wall breakthrough is allowed (keyword landlord) or is possible. In these cases, of course, the corresponding devices cannot be installed.
Be sure to ask your landlord for permission before installing.
Another major drawback of wall mounting is the fact that the loudest components of the air conditioner are in the room to be cooled. The noise background is therefore correspondingly high with these devices.
Monoblock air conditioning systems without exhaust air hose, i.e. window air conditioners, are a rather ineffective and above all outdated way of cooling a room.
Who is an air conditioner without an exhaust hose suitable for?
Air conditioners without exhaust air hose combine many disadvantages of split air conditioners with those of mobile air conditioners. For this reason, such a device is hardly worth it nowadays.
Instead, you should opt for a split air conditioner or a mobile air conditioner.
Purchasing criteria: Based on these factors, you can compare and evaluate air conditioners
Below we give an insight into the purchase criteria below to help you evaluate and compare the air conditioners:
- Size and weight
- Cooling capacity / BTU
- Cooling for room size up to
- Monoblock vs. Inverter Split Airconditioners
- Timer / Remote control / Exhaust air hose
- Power consumption / air circulation
- Energy efficiency class
- Cooling, heating, humidifying, ventilation and dehumidification
- Cooling type
Size and weight
A purchase criterion can be size and weight. Especially if you are considering a mobile air conditioner, less weight and more compact size can be beneficial.
The orders of magnitude range at an average of 90 x 50 x 30 cm. The weight of monoblock refrigeration units is between 11 and 30 kg or 27 to 50 kg for inverter splitting devices.
For window air conditioners, these factors are also important because they must be adapted directly to the window or wall.
Cooling capacity / BTU
An essential criterion when purchasing air conditioning is the performance it achieves.
The cooling capacity indicates how much heat energy is dissipated per unit of time.
On the one hand, it has an impact on the resulting operating costs and on whether the cooling capacity of the air conditioning system is appropriate for the room size to be cooled.
You can calculate the cooling power yourself with a simple formula:
- A cooling capacity of approx. 40 watts is to be expected per cubic meter of room volume.
- An additional cooling capacity of approx. 100 watts is expected per person.
The BTU shows you the maximum cooling capacity. When you talk about BTU, it’s about heat energy. BTU, known as the British Thermal Unit, gives the cooling capacity in one hour for air conditioning.
The larger your room to cool, the larger this value should be. 1,000 BTU/h correspond to about 293 watts, 5,000 BTU/h are about 1465 watts.
Cooling for room size up to
This criterion is important for the purchase, as one should pay attention to optimal room cooling. Neither an undersized nor an oversized cooling capacity makes sense for the room to be cooled. With too little power, there may be higher power consumption and the room is still not cooled pleasantly.
Most monoblock air conditioners cool a room with a size up to 65 m3 best.
Inverter split air conditioning systems provide cooling of up to 120 m3 rooms.
Monoblock vs. Inverter Split Air conditioner
In the Decision section, we discussed the differences between these two types of air conditioners.
Depending on whether you prefer a compact device, which is usually easier to install, or a two-piece cooling system in which a compressor must be mounted to the outer wall and connected to the internal air conditioning module by a copper pipe or hose, you need to consider these two types.
In the indoor unit of the inverter split air conditioner, the actual air conditioning takes place, i.e. filtering, temperature control and regulation of the humidity.
The advantage is that the noisy components of the inverter split cooling unit are mounted outside and thus work subjectively quieter compared to mono climate units.
However, more cooling performance can also mean that the inverter split devices generate a higher noise level. However, it should be noted that they are more suitable for continuous use than a monoblock air conditioning system. Inverter split devices have another significant advantage: they work more energy-efficiently.
Timer / Remote control / Exhaust air hose
A timer is standard on almost all air conditioners and helps to set the cooling time. For example, the cooling can be switched off or run at a lower level while sleeping.
Using an app installed on a mobile device, you often have the ability to regulate cooling from another location or room. In addition, you should pay attention to whether the exhaust air hose is included in the delivery of a monoblock air conditioner.
Power consumption / air circulation
Electricity consumption is calculated in kilowatts per hour. Again, we recommend an inverter air conditioning system, as the rotation of the compressor adapts to the room temperature. Unlike on-off splitting systems, the number of compressor revolutions is reduced as soon as the desired temperature is reached.
Consumption should range from 140 to 346 kWh per year.
The air circulation indicates how much cubic meters of air is recirculated in an hour. It is also called the volume of electricity. The values here are between 330 and 650 m3/h.
Energy efficiency class
Since January 2013, the new EU Directive on the environmentally sound design of energy-related products has been in force, which distinguishes the calculation and thus the designation of the energy efficiency data SEER – values for refrigeration and SCOP – values for the heating operation.
These are seasonal efficiency data that reflect the efficiency of the air conditioner or heat pump throughout the year, depending on the climate.
SEER stands a Seasonal Energy Efficiency Ratio. This value indicates the power of the air conditioner in cooling mode over the entire cooling period. SCOP is the abbreviation of Seasonal Coefficient of Performance for the performance of the unit in heating mode over the entire heating period.
Basically, you should make sure that your air conditioner has at least the energy efficiency class A to use an energy-saving air conditioner and consume less power while maintaining good performance.
Cooling, heating, humidifying, ventilation, dehumidification
These four functions are performed by air conditioning. In theory, any air conditioner can heat, but in practice, this is often not the case. Furthermore, it is questionable whether the heating power is better than that of other heating systems.
These four factors contribute to a pleasant indoor climate, increase air quality, reduce germs and pests and can have a positive effect on allergy sufferers. The more functions the air conditioning system has, the more possibilities there are to create the optimal room atmosphere.
The volume is an important purchasing criterion, as the air conditioning is always in the room where we work, sleep and live.
65 decibels is standard, but in continuous operation, they are perceived subjectively as noisy. At this volume, we recommend an inverter split air conditioning system for continuous operation.
The cooling method tells you which technology the air conditioning works with. Coolant air technology is usually used, sometimes also air-to-air technology. In principle, the use of coolants is critical, as they are not very sustainable.
In addition to indirect CO2 emissions, air conditioning systems that operate according to the compression principle pollute the climate with their greenhouse-effective cooling emissions.
The refrigerant consists of semi fluorinated hydrocarbons (HFCs) which are used either as a pure substance or as a mixture of substances.
The refrigerant R407C and R410A are often used. In central systems, cooling can be carried out by means of cold water with a range of natural refrigerant R290 or R717 (ammonia).
Trivia: Facts worth knowing about air conditioning
How long have air conditioners been around and who invented them?
The first fully functional air conditioning system according to today’s principle is said to have been invented by W.H.Carrier in 1911. This means that air conditioning systems have been around for more than 100 years. Car air conditioning systems were first used by Nash in 1938 and by Studebaker in the same year.
Are there air conditioners without exhaust air hose?
Air conditioners without exhaust air hose are also called monoblock devices. They are mobile and can be purchased at low prices. An air conditioner without exhaust air hose cools by distributing cool air using cool water, cooling pads, ice cubes, etc. It is also possible to use coolant.
Can I install an air conditioner myself or do I need a specialist?
Central and decentralized air conditioning systems such as a split air conditioning system and a window air conditioning system are installed by specialist companies. In most cases, a permit must be obtained in advance from the landlord or the municipality.
A specialist is absolutely necessary for a guaranteed full-fledged functioning.
What is the performance of air conditioning?
- Mobile air conditioners: the cooling capacity of approx. 2 kW
- Compact/window units: The cooling capacity of approx. 7 kW, are installed directly into the wall.
- Split devices: Consist of the outer and inner part. The connection is made via an insulated copper pipe, which transports the refrigerant. Cooling capacities of up to 15 kW can be achieved.
In continuous operation, air conditioners are a power-eater and can drive up operating costs.
What are the effects of air conditioning on the living environment and health?
The impact of air conditioning on the living environment and productivity at work is controversial and is influenced by many individual factors. The advantages are the fresh air supply, which a fan, for example, cannot offer.
A temperature of 20 to 24 °C is the perfect basis for a pleasant living atmosphere. If the air conditioner is set to cool, there may be a “cold shock” and as a result a cold.
- Fresh air supply
- At about 20 °C, humans are 100 percent powerful
- 40 percent of respondents feel affected by poor ventilation and air conditioning
- Energy consumption, waste heat and operating noise
Is it possible to install an air conditioner afterwards?
In principle, it is more difficult to install a central air conditioning system or wall or ceiling air conditioning system afterwards.
In the case of split air-conditioning units, i.e. two-part systems, which are usually connected to a pipe and run through the wall, a wall breakthrough is usually required. This significant change in construction cannot be carried out without permits.
What do I do if the air conditioner stops cooling?
There are several options:
- Thorough cleaning and filter replacement
- Replace coolant
If that doesn’t help or you’re unsure, you should hire a specialist company for maintenance.
What refrigerant do I need for air conditioning?
An important factor of air conditioning is the coolant. Here, care should be taken to ensure that it is as climate-friendly as possible. Almost completely without any negative impact on the environment cool air conditioners with ice. However, it should be borne in mind that the ice gradually melts and needs to be renewed again and again.
Alternatively, such devices can also be operated with cooling batteries. Air conditioners with ice cooling are extremely economical with a power consumption of around 60 to 70 watts.
They are also cheap to purchase. Already in the price range from 70 to 120 euros, there is a large selection of different models, most of which also have air filters or humidification and dehumidification functions.
Depending on the model, water consumption is between half and one litre per hour. Depending on the temperature and size of the tank, operating times of up to 12 hours per ice filling are possible.
How do I disinfect air conditioning?
You can disinfect the system with the help of special sprays. They disinfect the evaporator and ventilation system of the air conditioning system.
This will create the basis for fresh and aseptic air. In this way, the ventilation system is both hygienically clean and consequently freed from disturbing odours. Clean air is very important.
Disinfect air conditioning: tips and tricks for self-help
Various manufacturers offer the right disinfection sprays at reasonable prices. About 99.9 per cent of harmful microorganisms (such as bacteria and mold spores) are removed by them.
Be sure to buy a special spray for mobile air conditioning systems and not a spray for car air conditioning systems. This is not suitable for mobile air conditioning.
Disinfect monoblock air conditioning – this is how you can:
To properly disinfect a monoblock air conditioner, you should follow a few steps that we have written down here.
- The first step is to place newsprint or cardboard under the air conditioner to protect the floor from the foam of the cleaning or disinfectant spray.
- Then remove the pollen filter from the air conditioner and spray foam into its hose.
- After that, the air conditioning is switched to the highest level.
- Spray again after 15 seconds.
- This process is repeated several times.
- Then you should leave the room and close the door.
- After about ten minutes you go back in and open all the windows to ventilate the room.
Through these few steps, you can make sure that your air conditioner is properly disinfected.
When and why do I have to have my air conditioner service serviced?
The reasons for the regular maintenance of the air conditioning are manifold. For example, the formation of fungi and germs is prevented. This can happen if the air conditioner filter is faulty.
If the filter is not replaced from time to time, the cooling capacity also decreases because dust blocks the air flows. Mold can also cause expensive consequential damage. In addition, germ- and bacteria-contaminated air circulation does not have a particularly positive effect on concentration and performance.
Air conditioners with more than 3 kg of coolant should be tested for leakage at least once a year. Replace the coolant regularly and refill the air conditioner to continue to do a good job.
For smaller air conditioners for only one room, maintenance is less complex. Here, an inspection every 2 to 3 years is sufficient.