How Do Window Air Conditioning Units Work?

Most buildings are air-conditioned by large, central units that require a lot of space for their outdoor compressors. Any structure utilizing this type of cooling system must also have an indoor unit, which consists of a large (and sometimes loud) fan, not to mention an elaborate system of ductwork. While this way of cooling is great if your home is equipped for it, not every building has the necessary space or infrastructure for such a large volume of machinery.

Fortunately, those of us occupying smaller spaces have the option of using window air conditioning units to stay cool during the hottest days of the year. But how do window air conditioning units work? And how do you decide if they’re the correct choice for cooling your home?

In this article, we’ll discuss some of the science and technology behind window air conditioning and help you to determine if it will fit your needs. Finally, we’ll offer some advice on how to shop around to get the best deal on a window air conditioning unit.

The Science Behind Cooling

There are many different types of air conditioning units, ranging from humongous, industrial-scale systems that are designed for cooling massive commercial structures to window units that are the subject of this article to miniature ones like those that provide air conditioning for automobiles. Regardless of their size, however, the technological principles underpinning them are always the same. It also happens to be the same technology that allows your refrigerator to keep food cool.

The technology behind air conditioners relies on certain gases that are used as refrigerants. In modern HVAC units, hydrofluorocarbons (HFCs) are most commonly used, with one called r134a having recently increased dramatically in popularity.

Thanks to the laws of physics, gas increases in temperature when it is placed under pressure. An air conditioner, therefore, pressurizes the gas, causing its temperature to increase greatly. The heat energy in the gas eventually dissipates as it returns to an equilibrium state with its surroundings (that is, room temperature), meaning that when the gas is returned to a state of lower pressure, it then cools down to a much colder temperature.

As long as the air conditioner is operational, it will cycle the coolant gas between higher and lower pressure, which will, in turn, reduce the temperature of any air that passes over the refrigerant coils. This air can then be circulated throughout the home to cool it down.

How the Air Is Circulated

While the principle behind cooling is always the same, where air conditioning units differ is in how they transport the cooled air throughout a building. In many houses and commercial buildings, there is a compressor unit installed somewhere outdoors that uses a large fan to blow the cooled air through the ductwork in the building. It then enters each room through the vents, bringing the rooms to the temperature that has been programmed into the thermostat.

Of course, while this method is certainly effective, it requires a building to have two things: first, somewhere to install the outdoor compressor and, second, the aforementioned system of ductwork. For houses, the air compressor is often installed in the backyard or somewhere else out of the way on the property. Commercial buildings usually have their compressors installed on the roof somewhere.

Where does this leave apartment buildings and small houses, though? Many of them do not have a lot of outdoor space or room or structure strength on the roof for these large compressors. Often, they also do not have ductwork installed, and they may not have the space for it to be installed either.

Window Air Conditioners to the Rescue

If you live or work in a space that does not have room for a large compressor or a lot of ductwork, then you may benefit from using a window air conditioning unit. But how do window air conditioning units work? How are they different from the large central HVAC units we’ve mentioned above? Well, as we’ve said, the way they cool air is the same: through the use of pressurized coolant gas. The way they circulate air, however, is a little different.

Rather than being composed of many different parts that are installed in various areas throughout a building, all of the hardware in a window air conditioner is encased in a single, medium-sized box. This box can be installed in a window, with the box itself leaning toward the outside. The window is then closed, and a seal is created so that hot air from outside does not seep in and undermine the operation of the air conditioner. Your window air conditioner then draws air from outside, cools it, and blows it into the room.

Window air conditioners are excellent for cooling smaller homes and apartments. However, because they are not as large as central HVAC systems, they lack the capacity to cool larger houses and commercial buildings unless you buy several of them, which often isn’t cost-effective. Nevertheless, if you are in a space that lacks the room or the infrastructure for a larger system, a window air conditioner may just be perfect for you.

Shopping for a Window Air Conditioner

As with any major purchase, you should take some care when you are shopping around for a window air conditioner. Make sure you do some research ahead of time. One important consideration is to purchase a unit that is the correct size for your space. Air conditioners are rated for their cooling power, which is measured in BTUs (short for British Thermal Units). Look for one that generates the correct amount of BTUs for the square footage of your space. If the unit is too large, it will be needlessly expensive to run. If it is too small, it will struggle to cool the space effectively, which will also drive up your energy bill.

Finally, you should make sure you have a unit that can be serviced and repaired easily. Otherwise, you may be forced to shell out more money than you need to when the time comes to perform otherwise routine maintenance on your window air conditioner. Choose a unit that has a manufacturer’s warranty. Otherwise, make sure you have access to a trusted contractor—preferably one that has expertise in air conditioning, like the professionals at Entek HVAC—who can perform any repairs or maintenance that your AC unit needs.