Different Types of Air Filters: What You Need to Know

Air filters are devices that remove particles, such as dust and dirt, from the air, and there are many types of air filters. Pleated filters consist of a cloth medium made of polyester or cotton. The material is organized into folds to increase the surface area of the filter. Therefore, filters that have more pleats are more effective than those with fewer folds.

These filters are slightly more expensive than fiberglass filters, but they are also more effective against pollutants. They even capture smaller air pollutants, such as pollen, pet dander and mold spores. Pleated filters are available in reusable and disposable versions. Because of the high efficiency of these filters, they are popular with people who have air conditioning allergies or other respiratory problems. Fiberglass filters are often the most economical and least efficient type of filter.

They're usually disposable, meaning you'll need to replace the filter about once a month while the system is in use. Ultra-Low Particulate Air Filters (ULPA) can remove even smaller particles in the air, up to 0.12 microns in diameter with a minimum efficiency of 99.99%. ULPA and HEPA filters have the same working mechanism; however, ULPA filters have lower media porosity. Therefore, their higher density of filter media reduces airflow, resulting in higher energy consumption than filters.

In addition, they have a shorter lifespan and are more expensive. However, this type of filter generally does not fit residential HVAC systems that have size and airflow restrictions to consider. HEPA filter will remove 99.97 percent of airborne contaminants and allergens. This includes dust particles down to 0.3 microns. They are mainly used to filter the air in homes and other living spaces.

This type of filter consists of layered fiberglass fibers placed one on top of the other. Typically, the fibers are reinforced with metal grids, which prevents failure and collapse. Reusable area filters are washable filters that can simply be cleaned and used again. This type of filter is usually more expensive than the disposable type and has a low MERV rating of between one and four. This makes reusable air filters prone to mold and mildew.

Washable electrostatic air filters are based on an electrostatic filter medium, which is usually made of woven polypropylene or polyester. They are responsible for capturing unwanted particles and preventing them from circulating in the air. Activated carbon air filters are effective in removing gaseous pollutants, fumes, vapors and odors present in the air. As air passes through the filter, activated carbon absorbs odors and gases and neutralizes them. The filters are mainly composed of fiberglass mats, which trap particles as an air stream flows. Exhaust filters are installed in ventilation systems to filter air from an enclosed space before releasing it to the environment.

As the air stream encounters the photochemical process, harmful particles, such as mold and bacteria, are neutralized. UV air filters kill bacteria, viruses, molds and other pathogens by destroying your DNA with powerful short-wave ultraviolet light. Charcoal air filters are commonly used in air purifiers, range hoods (along with aluminum screens), bathroom fans, and microwaves. When buying a replacement air filter, you may be overwhelmed by the different types of HVAC filters available for use with your boiler, air conditioner, or heat pump. Engine air filters are rectangular pleated filters that remove particles from the air before it flows into a vehicle's engine. The ultraviolet lamps in the filters disinfect the air passing through the HVAC system using their powerful germicidal irradiation.