Nothing is quite so refreshing on a hot summer day as air conditioning. Today, people tend to take it for granted that they will find air conditioning in public places like movie theaters, shopping malls and museums. Of course, many people also insist on having an air conditioning unit right in their own homes.
While many families rely on and appreciate the utility of the air conditioner, fewer of them realize exactly how these amazing machines work. If you’ve ever wanted to know more about air conditioning, here’s your chance to find out.
The History of Air Conditioning
Since ancient times, people have been anxious to find relief on sweltering days. It’s what led the ancient Egyptians to hang dampened mats over all of their doorways. As water evaporated from the mats, indoor temperatures dropped and a little extra moisture helped to refresh rooms.
Additionally, the ancient Romans relied on their system of aqueducts to move water through indoor pipes that could fairly efficiently cool their homes. It wasn’t until the middle of the 18th century that any further significant strides were made toward modern air conditioning. Inventors Benjamin Franklin and John Hadley began exploring the refrigerating properties of various liquids in 1758.
Franklin had already discovered that the faster a liquid evaporates, the more potent its refrigerating effects were. Working with Hadley, he then used a bellows and ether to cool a mercury thermometer down to a chilly 25 degrees below freezing.
By 1820, Michael Faraday was working with the refrigeration characteristics of gases. Faraday learned that he could compress and liquidize ammonia, then allow it to evaporate. This experiment significantly cooled his laboratory.
Carrier and Modern Air Conditioning
By the middle of the 19th century, a Florida physician named John Gorrie was inventing a “cold air machine” that used compressed air and water to keep his yellow fever patients cooler.
However, the machine that most closely resembles the modern air conditioner wasn’t invented until 1902. It was in that year that the Sackett-Wilhelms Lithographing and Publishing Company of Brooklyn, New York was looking for a way to keep the air in its factory cool and less humid. Up-and-coming engineer Willis Carrier was assigned the job of getting excessive humidity out of the factory’s air.
By the next year, Carrier had developed a system that involved a number of chilled coils. This kept the humidity levels in the factory comfortable, and it is this machine that forms the backbone of the modern air conditioner. The machine would be employed in many plants and mills over the next several years. By 1914, the air conditioner had made its debut in a private residence.
How Do Air Conditioners Work?
While air conditioning units come in sizes that are small enough to fit in a window or large enough to cool an enormous factory, they all operate along the same basic principles. An air conditioner emits cold air to an enclosed space, like your home, while also removing heat and humidity from indoor air.
The cooled air is returned to the indoor space, and the undesirable heat and humidity are transferred outside. While early inventors experimented with liquids like ammonia and ether, modern air conditioners use a liquid refrigerant. The two most common refrigerants in home air conditioners are R-410A and R-22, both of which are hydrochlorofluorocarbons, more commonly known as HCFCs.
HCFCs excel at switching from the liquid state to the gaseous state. Because of this facility with phase transitions, HCFCs are perfect for use as refrigerants.
Air conditioning systems also include three main mechanical components and a variety of other parts. These are the evaporator coil, condenser coil and compressor. It is these components that cause the refrigerant to go through phase transitions from the liquid state to the gaseous state.
The compressor’s responsibility is to raise the temperature and pressure of the gas phase refrigerant. The refrigerant gas is sent to the condenser coil, where it is transitioned into a liquid. Next, the refrigerant is sent indoors to the evaporator coil where is evaporates, thereby cooling the indoor coil.
The air conditioning unit also includes a fan that is responsible for blowing the indoor air across the frosty evaporator coil. It is at this point that the warmer air inside the home gets absorbed and mixed with the refrigerant. This effectively cools the air, which can now be circulated throughout the home. Meanwhile, the heated evaporated gas is transferred outside to the compressor.
The heat is delivered outdoors as the HCFCs return to their liquid state, beginning the cycle all over again.
Here’s a more succinct description of what each mechanical component in an air conditioner does:
- The evaporator has cooling coils that use a refrigerant to lower levels of heat and humidity in the air.
- The blower, sometimes called a fan, moves the air over the evaporator and dispenses the cooled air.
- The condenser has hot coils that collect hot air and release it to the outdoors.
- The compressor is the component that transfers refrigerant back and forth between the condenser and the evaporator to cool the indoor air.
- The fan helps by blowing air over the condenser to distribute the heat outside.
- The filter removes particles from the air, improving indoor air quality.
- The thermostat regulates how much cool air gets distributed indoors.
What About Central Air?
Frequently, you’ll hear air conditioning systems referred to as central air. Basically, this means that air is cooled at a central location, then is distributed to various locations throughout the home via ductwork and fans.
A central air system includes components such as:
- A thermostat to control the operation of the system
- An outdoor unit including a compressor, condenser coil, and fan
- An indoor unit, which may be called a fan coil or furnace, that features a fan and evaporator coil
- Copper tubing to circulate refrigerant between the indoor and outdoor units
- An expansion valve to regulate how much refrigerant makes it to the evaporator coil
- Ductwork to circulate air from the indoor unit to the various rooms of the home
Because central air systems typically have both indoor and outdoor units, you also may hear them referred to as split-system air conditioners. Split-system air conditioners come in a variety of models.
Some of these are the very basic single-stage systems while others offer the enhanced noise control and efficiency of a two-stage system. The most sophisticated models offer a multi-stage system that is far quieter and more efficient than the other two. Regardless of which one is used, a split-system air conditioner provides steady, consistent and reliable cooling.
Is a Packaged Air Conditioner for You?
What if you don’t have the room in the attic or a closet for the indoor unit of a split-system air conditioner? In this case, a packaged air conditioner may be the perfect solution. That’s because these machines feature the condensing coil, compressor, blower fan and evaporator in a single unit. Just like other air conditioners, these units remove warm air from inside the home, replacing it with cooler air that is distributed through ductwork. Available as both single-stage and two-stage systems, packaged air conditioners also may offer better energy efficiency through the inclusion of a multi-speed blower fan.
Have You Heard of Ductless Air Conditioning?
While technically not central air system, ductless air conditioners can help to keep your home cooler. Their cooling efforts are directed to specific areas of your home, like the bedroom so that you can sleep better on hot summer nights. The installation process is far less invasive because no ductwork is required.
The indoor unit of a ductless air conditioner may be mounted on a wall, ceiling or floor of the room that it is intended to cool. Some people like these systems because it allows them to create temperature zones throughout the house.
Get Reliable Advice from Delaware Heating and Cooling
If you are curious about the many ways in which an air conditioning system might make your home more comfortable and livable throughout the hot summer months, then contact Delaware Heating and Cooling. We’ve been helping our friends and family stay cool in the summer and warm in the winter for many years now, and you can rely on us to provide trustworthy, sensible advice that enhances the energy efficiency of your home and saves you money.
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