Air conditioners use filters to keep the air clean and free of hazardous contaminants and allergens. There are several types of filters available for residential HVAC systems, including fiberglass air filters, pleated air filters, and air cleaners. Fiberglass air filters are disposable and the most economical option, while pleated air filters are made of cotton or polyester pleats. Air cleaners are devices for filtering particles from the air. Most central air conditioning units have two or more filters.
These filters are generally made of spun fiberglass or pleated paper or cloth, encased in a rectangular cardboard frame. Fiberglass filters are about an inch thick and are common in older systems, while newer models use thicker pleated filters. As the unit circulates between indoor and outdoor air, the filter traps particles and contaminants such as dust, mold, pet dander, and fungal spores. The mesh of the filter becomes denser as it traps these materials, preventing them from entering the indoor environment. Not all filters are built equal, so choosing the right filter depends on what you need to purify from the air.
Fiberglass filters should be changed every 30 days, while higher quality pleated filters should be changed every 60 to 90 days. Media filters are ideal for filtering bacteria and other small airborne contaminants. We measure how well an air filter removes dust, pollen, and smoke from the air, as well as how freely air flows through the filter at any fan speed. Pleated filters have an advantage over creaseless options because they increase the filter surface area for better filtering. Some people need HVAC system filters that keep the air free of allergens and other contaminants, while others just need a basic filter to get the job done. In most cases, a standard filter cannot be replaced with a true HEPA filter because the ductwork is not designed for it.
High-efficiency filters that are also cost-effective are best for homes, but other considerations should include whether there are pets in the house, if mold is a threat, and how often filters should be changed. If you live in a rural environment with clean air and no pets, a HEPA filter may not be what you need since a standard filter can do the job. It's important to change or clean your filter regularly to ensure good air quality and prevent damage to your HVAC system.