Have you asked yourself ‘How does air conditioning work ?’ It’s very easy to take air conditioning for granted – you want to cool down, so you adjust the temperature button and hey, within a few seconds the air around you is cooling down. But how does it work?
Well, there are a lot of similarities with the humble refrigerator – they both work in a similar way.The main difference between the two is that a refrigerator keeps a relatively small area cool within it’s own structure and air conditioning uses the walls of your house, hotel room or office to keep the air inside it cool and the warm air outside.
The principle of air conditioning
The principle of air conditioning is based on a concept where a chemical (a refrigerant) converts from gas into liquid and back to gas, at relatively low temperatures. When this occurs, a process called phase conversion takes place and the liquid starts to absorb heat. This heat is transferred from the air inside the room to outside the building.
How an ac unit works
There are three main parts to the air con unit; an evaporator, a compressor and a condenser. Usually the condenser and compressor are positioned outside the unit and the evaporator would be positioned inside the room.
The fluid goes into the compressor in a low pressure gaseous form and then gets compressed to squeeze the molecules together tightly. The tighter they are, the warmer the temperature. This fluid then leaves the compressor as a higher pressure gas and then moves to the condenser. The gas now changes to a liquid and is now much cooler as the heat dissipates. The fluid then moves on to the evaporator where it returns to a low pressure gas. With this, the surrounding air loses its heat. A fan connected to the evaporator circulates the air around the room.
The process is repeated over and over until the temperature reaches the selected temperature on the thermostat at which point the air conditioning unit is switched off. When the air inside the room heats up again, the air conditioning starts up again and repeats the process to maintain the desired temperature.
Air conditioners don’t just cool and heat the air, they also dehumidify the air, removing moisture from the air. If a room contains a lot of moisture then the sweat on our bodies can not evaporate and we feel hot, so removing the moisture helps our sweat evaporate and we cool down. The air conditioning unit handles this through the evaporator where heat is absorbed and moisture is removed, leaving the room cooler and drier. In fact the first air con unit was initially built to remove moisture and cooling was just a consequence of this.
Do all air conditioners remove humidity ?
Yes and that’s because of the air conditioning process itself. During air conditioning the warm air moves over the evaporator and as it condenses, moisture is extracted from the air. You could say that air conditioners inadvertently reduce humidity because that’s what happens when you use an air con unit to cool a room. It must be stressed however that an air con unit won’t remove moisture as efficiently as a dehumidifier would.
What kind of air conditioner should I get ?
You firstly need to establish what kind of area you’re looking to cover. If your air con unit is too small for this area then it won’t cool the place down nearly enough. If the air con unit is too big then it won’t dehumidify the place enough.
Follow these steps to get an initial estimate of the size of air con unit that you’ll need…
- Measure the total area of the room you want to cover (eg 12ft x 18ft = 216 sq ft)
- Find out what BTU (British Thermal Unit) rating you need…
|Area of Room||BTU Required|
|150 – 350 sq ft||5000-8000 BTU||Browse products|
|350 – 550 sq ft||8000-12000 BTU||Browse products|
|550 – 1050 sq ft||12000-18500 BTU||Browse products|
|1050 – 1600 sq ft||18500-25000 BTU||Browse products|