Most of us have air conditioning systems in our homes – or at least window air conditioners. But how do they actually work?
It’s Science, Not Magic!
Central air conditioning systems blow cool air through the ductwork located in the walls and ceilings of your home. The insulation in your walls, floors and ceiling keeps that air inside. But where does that cool air come from?
Basically, it works like this: On a hot day, the air outside is warm. The air conditioning unit mounted on a slab of cement outside your home or on the roof uses fans to draw in that hot air. That hot air is then converted into cool air by removing its heat.
Science tells us that when liquid converts to a gas – through a process known as conversion – it absorbs heat.
An air conditioner’s compressor unit is an electrically powered machine that condenses and circulates a refrigerant – usually R-22 or R-410A – through the unit, changing it from a gas to a liquid. That liquid is then forced through an indoor evaporator coil or cooling compartment.
The indoor unit’s fan then circulates the inside air so that it passes across the evaporator’s cooled evaporator fins. The metal fins then exchange thermal energy with the air around them. As the fins warm up, they convert the refrigerant from a liquid back into a gas, removing any heat from the surrounding air.
As the heat is removed from the air, the air is cooled down. This cooled air is then blown into the rooms of your home via the ductwork.
We’re Not Done Yet!
The condenser – or the air conditioning unit located outside – then turns the vapor back into a liquid, removing the heat that was exchanged in the evaporator fins. This is why the air blowing out of an external central air unit usually is hotter than the outside air.
By the time the refrigerant fluid leaves the evaporator again, it is a cool, low-pressure gas that is read to be changed back into a liquid – and the process starts all over again until your home reaches the temperature that was set on the thermostat. This is known as a “closed loop” system.
Relatively New Technology
The first modern air conditioning was developed by accident in 1902 in Brooklyn, New York, by a young inventor named Willis Haviland Carrier. He was hired by the Sackett-Wilhelms Lithographing and Publishing Company to solve a specific problem: The moisture contained in the borough’s warm summer air was making it too difficult to apply layered ink to paper.
The young inventor solved the problem by blowing warm air across cold pipes. Because cool air can’t carry as much moisture as warm air, the humidity in the plant was reduced and the moisture content on the paper was stabilized. The fortunate side effect for the rest of us was that reducing air humidity also reduces air temperature!
Carrier’s Willis’ discovery first began to become widespread in theaters and other public places where people could go to cool off during the hottest days of summer. It was only much later that it began to be widely used in homes and businesses.
Convenient, Reliable Technology
Modern central air conditioning units are highly efficient systems that optimize the chemical and mechanical processes first used to cool air in that steamy Brooklyn printing plant. Today, modern AC units provide plenty of cool, comfortable air with the push of a button.