How does air conditioning work?

Different types of air conditioning systems and how they work

An air conditioner is a refrigeration appliance (like a refrigerator for example) that keeps the air cool in the room of the building where it’s installed. To do this, a liquid called refrigerant will circulate within the air conditioner in a closed circuit to capture the heat in the room and expel it to the outside of the home. Air conditioning is based on this refrigeration system. Let's take a detailed look at what an air conditioning system involves... There are many types of air conditioners, each with its own specific features. These include:

• Monobloc air conditioner: also known as a single-packaged air conditioner, this is a single indoor unit (containing the refrigeration cycle components) which you put in the room you want to cool. A single-packaged air conditioner is ideal for small areas of up to 30 m2.
• Split air conditioner (bi-, tri- or quadri-split): this type of air conditioning is divided into an outdoor unit and one (mono-split) or several (multi-split) outdoor units. An air con system with multiple units can heat several rooms inside the home.
• Reversible air conditioner: this air conditioning system can be used to produce cold air in summer and hot air in winter.
• Wall-mounted air conditioner: this can be monobloc, split or even reversible. A wall-mounted air conditioner is a fixed unit, most of the time installed high up on the wall of the room you want to cool.
• Mobile air conditioner: unlike a wall-mounted air conditioner, a mobile air conditioner can be moved from one room to another. This is a portable device that can be placed on the ground, with no lengthy installation process required. Portable air conditioners can be monobloc, split or reversible.
• Cassette air conditioner: this is in fact a split air conditioner whose indoor unit is not fixed to a wall but embedded in the ceiling (more specifically the false ceiling). One of the advantages of a cassette air conditioner is its unobtrusiveness: fitted directly into the ceiling, the unit won't take up any space in the room where it’s installed.

What are the important criteria for choosing an air con system?

Before choosing one air conditioning system over another, you should consider several criteria during the selection process:

• The power of the air conditioner: the cooling power required will depend on the size of the area you want to cool.
• The number of rooms to be cooled: you’ll have to choose between a fixed or mobile air conditioner depending on your needs. Indeed, if you need to cool your bedroom and your office at the same time, it may be best to invest in a mobile air conditioner rather than a fixed one...
• Appearance and volume of the unit: the size and appearance of the air conditioner may be among your selection criteria, especially if you have limited space and/or decoration is a major consideration for you.
• Noise: the air flow produced by the compressor, a problem with the motor, the condenser cooling, etc.: these are all issues that can cause unwanted noise. That’s why it’s important to pay attention to this point when choosing your air conditioner, and maintain the unit as the years go by (changing the filter, checking the motor, topping up the refrigerant fluid or gas etc.). Well-maintained air conditioners will also keep your home's relative humidity at the right level.
• Budget: air conditioning systems vary in price. For example, a single-packaged air conditioner costs less than installing a system with multiple units.

What are the essential components of an air conditioning system?

Regardless of the type of air conditioner, it will consist of four main components: condenser and evaporator coils, a compressor and an expansion valve. So, what exactly do they do?

The evaporator coil is placed in the indoor unit, which is located inside the room you want to cool, and will play a major role in the air conditioning system. This is the component that will capture the heat (calories) in the room and send it via the refrigerant to the compressor in the outdoor unit, thus expelling heat from the home. The warm air is ejected by the outdoor unit’s fan. The compressor heats the refrigerant and increases its pressure. The refrigerant is then cooled as it passes through the expansion valve and is finally sent to the evaporator coil to be blown into the room as cold air.

Air conditioning works by transforming the refrigerant from liquid to gas.

How do air conditioning systems heat a room?

Although it’s usually thought of as a way to cool the air in a room, air conditioning can also be used to heat a building in winter, as an alternative to traditional central heating. However, not all air conditioners can heat your home: to meet this need you have to use reversible air conditioning.

How do reversible air conditioning systems work?

Reversible air conditioning or air-to-air heat pump?

Air-to-air heat pump or reversible air conditioning: they’re actually the same thing! Unlike traditional air conditioning, reversible systems operate in air con mode in summer and heating mode in winter. So, reversible air conditioning has the advantage of ensuring optimal thermal comfort in all seasons, whether it's hot or cold outside.

How can you best heat your home with reversible air conditioning?

To heat a room in your house, reversible air conditioning captures the calories in the air in the room to convert them into heat that will be released via your appliance’s indoor unit. Nevertheless, in very cold winters and at particularly low temperatures, reversible air conditioning won’t be powerful enough to heat the room well. Then you’ll need to opt for extra heating solutions, not forgetting effective insulation of the walls, roof, windows etc.

How does Inverter technology work?

Air conditioning based on Inverter technology helps its user to save energy and optimise the life of their unit. Indeed, this technology enables you to adjust the air con’s power according to the temperature you want to maintain. The refrigerant will circulate more or less quickly inside the circuit to maintain a steady temperature. With air conditioning systems that use Inverter technology, there is no risk of sudden peaks in heat which can lead to excessive energy consumption.

The various models of air conditioner operate in broadly the same way (they all have a refrigeration cycle with a condenser, compressor, refrigerant etc.). Reversible air conditioning is different because it’s a system that provides both hot and cold air. Finally, Inverter technology can be the best option if you want to achieve a steadier temperature in a room.