The History of Air Conditioning and How it Works Today


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When homeowners are ready to replace the air conditioning unit in their home, they often start researching how an air conditioning unit actually works in order to make a better decision about the next one. Although this commonplace piece of machinery is found in almost every business or home, most people do not understand the history of this invention, how to give it the TLC it needs, and how people survived before electricity made air conditioning possible.

AC tech working on an air conditioner

Historic forms of air conditioning

The principles of cooling air on hot summer days before electricity was invented were simple. Basically, water needed to be evaporated around the lowest part of the home and then that evaporated water could be pulled into the house (before electricity allowed fans) by allowing hot air to go out through the top of the house. In the old days, it was common to build patios with bricks in order to both absorb water at night and evaporate when the sun was out during the day. By opening side doors to the patios, the cooled air was pulled into the house while hot air escaped through a chimney in the roof. As time went on, more advanced techniques were involved and ancient Romans noticed that aqueducts surrounding homes that facilitated plumbing were also a great way to get some natural air conditioning in the summer.

Other techniques that were developed before electricity involved storing ice in the wintertime and moving it into areas that were hot. Most of the time, this ice was used for food preservation and this is why some people call a refrigerator an “ice box,” for example. As a matter of fact, less than 100 years ago, many homes had a small wattage of electricity, but not enough to run a refrigerator. When electricity was increased and stabilized, both the refrigerator and the air conditioner came about, but AC was still a work in progress.

The beginnings of the air conditioner started with meat preservation

Many times, appliances have their beginnings in industrial history. The air conditioner is one example of that. Before automobiles were common and electricity was distributed evenly throughout the United States, the invention of the train and railways was a driving force in food commerce. It was during the mid-1800’s that techniques for shipping meat during the summer months made such large profits that new inventions that kept the meat from spoiling were always given attention. The ultimate goal of many railway moguls of the time was to ship meat instead of live cattle. They got their wish starting around 1867 when the first ice-related refrigerated railway car was invented by William Davis for a butcher named George Hammon. From there, the idea that you can refrigerate a space with ice became a primary pre-electricity form of food preservation.

Electric ice boxes and early air conditioners

Today, refrigerators and air conditioners are united because they are both home appliances that utilize compressors, an evaporator and a condenser to keep things cool. Refrigerators aside, the first real air conditioner was built to help with newspaper printing. The first inventor of this air conditioner understood that air pushed through cooled coils will create cooled air. The coils were cold because of a Michael Faraday discovery concerning pressurized ammonia and turning it from liquid to gas (which creates cold air in the process). Starting around 1928, less flammable liquids were used to create cooling such as Freon.

Four different types of AC used today

Over the decades, things have been perfected with air conditioning efficiency, and the market has expanded into four different types. The first most common is the window AC unit, the second most popular is the central air or HVAC system found in homes (called a “split AC”), and the others are custom-built commercial AC that cool malls or stadiums and the package AC units found in places like hotel rooms. In other words, most homeowners are only interested in a split AC or window unit when they contact HVAC contractors.

How the AC in your home works

When you turn on your on the AC or central air unit in your home, the first thing you hear running are two fans. This is the sound of the hot air being pulled out of indoors and leaving your home to go outside and the second fan is blowing cold air into your home. The second thing your AC will do is start up the coils. When these coils become cold because of the liquid-to-gas reaction of the coolant inside of them, air blows across them and into your home creating the cooling effect you desire. However, once the refrigerant becomes a gas and cannot cool the coils, the refrigerant will need to go through a phase to become liquified so it can return to the coils be used to make them cold again. In the split AC or central air units that have an outdoor component, you will find that the gas goes from inside the home to outside to get re-compressed into liquid from gas in a copper tube that is often cold when in use.

Differences between new and old AC

The concept behind air conditioners used in homes is simple because the idea is that hot air is pumped out of the home and into the outdoors while being replaced with cooled air. The way the air is cooled may vary, but most machines use coils filled with gas to create the cooled air. For this reason, it can seem confusing to homeowners that there are now incentives to replace air conditioners even though their warranties have not expired. In these cases, HVAC specialists might be referring to the new push by the federal government to have homeowners install energy-saving appliances like high-efficiency air conditioner units.

How to get the services you need for your air conditioning or HVAC

Did you know that with regular maintenance and inspections your air conditioning bill can be significantly reduced? When you hire a local HVAC contractor to take a look at your air conditioning periodically, you will reap the rewards directly in utility bill savings. In short, when your air conditioner is working harder than it should because it is in a state of disrepair, it will draw more utilities.

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