Air Conditioners – So How Do They Work?

June 9 2016

James Patten


It has come to the point where it’s getting very hot and we’re reaching for our air con controls. But have you ever wondered how they can turn your hot room into a cool paradise?

The first modern electrical air conditioner (also known as an AC unit) was invented in 1902. But how do standard air conditioners work? How have they developed over the centuries and what are their main uses? Here is what you need to know.

How Do Air Conditioners Work?

The fundamental idea of an air conditioner is that it extracts heat from a room within your house or office and then pumps cool air back in. To do this, a standard air conditioner contains two fans, one attached to the outside of the building and the other to the inside, with an axle connecting the two, as well as a pump, an evaporation valve, a condensing coil and an evaporating coil.

When the air conditioner is active, the pump condenses the coolant within the pipes of the AC. This passes through the condensing coil, which expels heat to the outside. The coolant then reaches the evaporation valve, where it does exactly what it says – it evaporates. Because evaporation results in a decrease in pressure, this leads to a decrease in temperature, so long as the occupied volume is the same on either side of the valve. The coolant is now a gas and flows to the evaporating coil, where it cools warm air coming in and expels cooler air. The coolant gas then returns to the pump and the cycle continues. The air flowing through the outside fan drives the axle which is connected to the inside fan, which completes the air conditioning process.

Female holding a remote control air conditioner iStock_000024353857_Small

How Have Air Conditioners Changed Over Time?

The first type of air conditioning used the process of evaporation cooling.  Egyptians used reeds that were moistened with water and hung in a window. The water then evaporated, which cooled the air inside the house. Romans used water from aqueducts to cool their houses by pumping it through the walls.

During the Enlightenment, advances in chemistry lead to the idea of modern-day air conditioning. Benjamin Franklin and John Hadley investigated how the process of evaporation can rapidly cool an object. At the turn of the 19th century, Michael Faraday worked with compressing certain chemicals to cool a liquid, which was eventually used to develop the first mechanical ice-machines. After this and by including axles with fans attached to encourage consistent air flow, the first modern-day air conditioner was invented and the rest is, indeed, history!


Main Uses of Air Conditioning

Air conditioning applications are generally split into comfort and process applications.

Comfort applications aim to provide an indoor environment with a stable temperature, despite changes in external weather conditions. These can vary for a specific scenario but the main applications include air conditioning for domestic households, cars, offices, restaurants and even sporting venues.

Process applications aim to provide a stable environment for a process to be carried out. Some applications include air conditioning for laboratories, hospital operating theatres, nuclear facilities, mining and physical testing facilities.


We specialise in providing high quality office and industrial air conditioning. If you would like to know more about how your business would benefit, and which system would be most advantageous for you, please get in touch!

Just contact us today on 01509 814 123 and we will be more than happy to answer any questions that you may have.

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