Most homes these days have a centralized air conditioning system that is utilized to cool off the entire home during the hot summer months. If you’re like most homeowners, you know that turning your thermostat to the cooling function and setting a specific temperature will make your house comfortable for your family to relax. However, beyond these simple actions, most homeowners are at a loss when it comes to understanding how the central air conditioning process actually works.
It’s a Heat Transfer Process
Before we get into discussing the actual specifics of how the air conditioning process works, it is important to touch on one thing. Air conditioning is not about putting coolness into the air. Rather, it’s about transferring heat from the air in your home to the air outdoors. By removing the heat from the air inside of your home, it creates a cooler environment for your family to relax in.
The Role of Your Thermostat
The first component of your home air conditioning system is your thermostat. This is the part that most homeowners are familiar with handling. When the summertime heat comes back around, you switch your thermostat to its cooling function. By default, the thermostat will read the actual temperature inside of your home and display it.
It will also display the temperature that you set. When the actual temperature in your home is higher than the desired temperature, your thermostat will signal to the rest of your air conditioning system that it’s time to turn on. The system will continue to run until the thermostat ensures that the actual temperature matches your desired temperature.
Venting, Filtering, and Moving Air
When the thermostat signals to the remaining AC components that they need to turn on, the air handler starts the process. This air handler is typically utilized for both air conditioning and heating in a split system setup. The air handler will work to force air from inside of your home into your ductwork.
Each room in your home will have at least two different vents. The supply vent will deliver cold air to the room. The return vent will pull in air from the room so that it can be run through the air conditioning system. As the air handler pulls in the air through the return vent, it makes its way through your air filter. If you have an air purifier installed in your ductwork, it will also make its way through there.
As the air flows through your air filter, it works to remove any unwanted pollutants and debris from your indoor air. The amount of debris that is removed from the air highly depends on the specific type of air filter that you have. The highest filtering air filter is the HEPA filter, which removes 99.97% of all airborne particles.
Transferring Heat to the Refrigerant
After the air moves through the ductwork and the filters, it will be directed over a metal evaporator coil. This coil is filled with a liquid called refrigerant. As the warm air goes over the evaporator coil, the heat transfers from the air to the refrigerant. This heat turns the refrigerant into a gaseous form.
During this heat transfer process, moisture from the air passing over the evaporator coil is naturally removed. It will drip on the evaporator coil and into the drain pan for removal. Removing some of this moisture from your indoor air can help to make it feel less humid inside and more comfortable for your family.
As the air that was forced over the evaporator coil had its heat removed, it becomes cool. This cool air is forced back through your ductwork and out the supply vents into the rooms of your home.
A Trip Outdoors
While you now understand where the cold air comes from during the air conditioning process, that’s not the end of it. For the process to continue to cycle, the refrigerant needs to be resupplied to the evaporator coil. Before that can happen, it needs to lose the heat that was transferred to it from the indoor air.
The heated refrigerant, which is in a gaseous form, is transferred to the outdoor compressor unit via copper tubing. When the refrigerant reaches the outdoor compressor unit, it goes through a condenser coil. As the refrigerant flows through the condenser coil, there is a fan in the outdoor unit that blows fresh air over the coil.
The heat from the refrigerant is effectively transferred again to the fresh air that flows over the condenser coil. This air is then forced to the outside and dispersed. This is why if you stand by your outdoor condenser unit, you’ll feel that it’s really warm right next to it.
Heading Back Indoors
When the heat has been removed from the refrigerant, it can go back into its liquid form. However, this refrigerant needs to make its way back inside in order to start the process all over again. The refrigerant is forced from the outside compressor unit through the copper tubing.
Before the refrigerant can reach the evaporator coil, it goes through an expansion valve. This expansion valve helps to change the pressure of the refrigerant so that it’s more susceptible to accepting heat to turn back into a gas. This valve also helps to regulate the amount of refrigerant that enters the evaporator coil at one time. Once the refrigerant exits the valve, it goes back into the evaporator coil, and the process starts all over again.
Putting It All Together
Learning how home air conditioning works can be a bit overwhelming. There are a lot of moving parts inside of your system that work in unison to make your home more comfortable during the summer months. Let’s take a moment and recap everything that we discussed above.
The warm air inside of your home is forced through the ductwork in through your filter and air purifier if you have one. It then goes over the evaporator coils and loses its heat due to the refrigerant. That cold air is redelivered through your supply ductwork to cool your home.
The heated refrigerant heads outside and loses its heat as it goes to the condenser coil. It makes its way back inside to the evaporator coil, where the process starts all over again. This process will continue to run until the indoor air temperature matches your desired set temperature on your thermostat.
Three Types of AC Systems
It’s crucial to note that the process we went over above is that of a typical split system air conditioner. This is the most popular type of home air conditioning unit on the market. However, there are two other types of air conditioners that you may have installed in your home.
The first is a packaged system. Instead of having two units, one indoors and one outdoors, a packaged system has all the components that a split system has—just put into one unit that sits outdoors. This is ideal for homes that don’t have enough room for the indoor components that a split system requires.
The second type of air conditioning system is a ductless system. This type of system is comprised of wall-mounted units that are connected via copper tubing to an outdoor compressor unit. This type of system is recommended for homes that do not have existing ductwork.