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06.09.2024
Brooke Kirshne
A central air conditioning system doesn’t just cool your home or office space, it also provides cleaner, healthier air by filtering out dust, pollen, and other particles. Many systems use a single filter to accomplish this, but in some cases, you may find two filters installed. This dual-filter setup is a practical feature designed to improve both airflow and filtration, especially in larger homes or buildings with complicated layouts. By strategically placing two filters, these systems manage airflow more effectively and ensure that pollutants are captured from different areas before circulating clean air back into the living spaces.
The need for two filters often arises due to certain system designs, such as having multiple return air ducts or an air handler with dual filter slots. In homes with many return ducts, each duct may need its own filter to purify the air pulled from each zone, preventing dust and pollutants from re-entering the system. Some air handlers are built to accommodate two filters, providing extra filtration for improved air quality, a feature especially beneficial for people with allergies or respiratory issues. So, why exactly does your central air conditioning system have two filters? In this blog, we’ll explore the reasons behind this setup and how it improves your indoor environment.
What Is A Central Air Conditioning System?
A central air conditioning system, or central AC, is designed to control the temperature across an entire home or building, compared to single-room air conditioners that only cool individual spaces. This type of system distributes cooled or heated air to multiple rooms through a network of ducts, allowing consistent comfort throughout the home. The system relies on an air handling unit (AHU) that houses both heating and cooling coils to adjust the indoor climate according to the thermostat's settings.
Air filtration is a key component of this system, as it removes dust, pollen, and other particles, in order to improve indoor air quality. The airflow starts with a fan in the indoor unit that pulls warm air from inside the home through return air ducts. This air travels through a filter to remove dirt and particles before reaching the evaporator coil, where it is cooled with a chemical coolant. The cooled air is then pushed back through the ductwork to circulate in each room.
For larger homes or spaces that require additional filtration, you may notice two air filters in the system. This dual-filter system improves air quality and efficiency by ensuring that pollutants are effectively removed while maintaining continuous airflow, particularly in homes with high dust or allergy levels. The second filter provides an extra layer of protection, for cleaner air and reduces strain on the system’s components for longer-lasting performance.
Types Of Central Air Conditioning System
Knowing the type of central air conditioning system you have is essential, especially if you're wondering why your system has two filters. Different types of central air systems have distinct designs, each with specific filtration needs that affect air quality, energy efficiency, and cooling performance. Here’s a look at the main types and how they function:
Split-System Central Air Conditioning
A split-system central air conditioner is a common choice for homes that already have a furnace but need a way to cool the house. It has two main parts: an outdoor unit with the condenser, fan, and compressor, and an indoor unit with the evaporator coil. The evaporator coil is usually connected to the furnace’s supply duct. This design helps to separate heating and cooling, making it a cost-effective option for homes that don’t have AC but do have heating. Split systems may have two filters, one in the return air duct and another near the evaporator coil, to keep the air clean and protect the system.
Packaged Central Air Conditioning
A packaged system is a central air conditioner where all the parts, like the evaporator coil, condenser, and compressor are in one unit. This unit is often placed on a concrete slab outside the home or on the roof. Packaged systems can also include a furnace or electric heating coil for both cooling and heating in one system. For homes with large spaces or more airflow needs, packaged systems may use two filters to ensure smooth airflow and keep out dust and debris.
Ductless Mini-Split Systems
A ductless mini-split system is an air conditioning solution that's perfect for homes that don’t have ductwork or for cooling specific rooms instead of the entire house. It has two parts: an outdoor unit and wall-mounted indoor units for each room. These systems are energy-efficient and save money by cooling specific areas instead of the whole house. While mini-splits don’t use duct filters, each indoor unit has its own filter to keep the air clean in the room.
Why Does Your Central Air Conditioning System Have Two Filters?
In some central air conditioning systems, you may notice there are two air filters instead of just one. This design is often due to several factors that can affect how much air the system needs to filter. Here are some reasons why your central AC might have two filters:
1. Multiple Return Ducts
In larger homes or buildings, the HVAC system has to handle a larger volume of air. As a result, these systems may have multiple return air ducts, which are responsible for pulling air from inside the home to be cooled. For homes with air conditioning systems that are 3 tons or more, it's common to have more than one filter grill. When the number of rooms and vents increases, so does the need for more return air, which requires more effective filtration. One filter might not be enough to handle the extra air, so a second filter is added to ensure that the air quality stays high and the system works efficiently.
2. Multiple Central Air Conditioning Systems
In multi-story homes or large buildings, cooling all floors evenly can be a challenge. Often, the upper floors may not cool down as efficiently as the lower ones. To address this issue, separate central air conditioning systems are sometimes installed for each floor. Each system will have its own filter to maintain good air quality and optimize the cooling process. As the volume of air handled by each system increases, having multiple filters becomes necessary to ensure proper filtration and system performance.
3. Air Handlers With Dual Filter Slots
Some air handlers are designed with two filter slots. The idea behind this design is that one filter removes larger particles from the air, such as dust and dirt, while the second filter is meant to capture smaller particles like pollen and pet dander. Although this setup can improve air quality, it can also lead to issues if not properly managed. Many HVAC professionals advise against using two filters at the same time in these slots, as it may restrict airflow. This could cause the system to work harder and potentially lead to damage or reduced efficiency over time. For example, if the two filters are of different sizes, such as a 5-inch filter in one slot and a 1-inch filter in the other, the airflow could be interrupted, decreasing the effectiveness of your central air conditioning system.
Conclusion
This blog covers why your central AC might have two filters and how they help improve air quality. Central AC cools an entire home, unlike portable units that cool only single rooms. Having two filters may be necessary if your system has multiple air ducts, dual filter slots in the air handler, or multiple AC systems in one building. While two filters in your central air system can improve air quality and system performance, it’s important to understand why they are necessary and how they function.
Be sure to follow the manufacturer's recommendations for filter replacement and maintenance to ensure your system runs smoothly and efficiently. If you are wondering where you will get the right filter for your central air conditioning system, then don’t worry; you have come to the right place. If you need the right filter for your central AC, Custom Filters Direct has you covered. We also customize filters to fit the specific dimensions of your AC system. Call us at (877) 749-1748 to place an order today!
