Written by: Your Filter Connection The air filter is one of the most important parts of your HVAC system, so you should replace it regularly. HVAC systems use air filters to increase longevity and efficiency of your heating and cooling system by protecting it from dust, dirt and other airborne particles. Whether heating or cooling your home, most HVAC systems work by circulating air through a series of ducts throughout the interior of a building. All air passes through the central unit where the air conditioner filter is located. As air circulates through the central unit, it passes through the air filter, which provides a physical barrier between air intake and the moving parts of your HVAC system. In addition to protecting the working parts of your heating and air conditioning system, some replacement furnace filters are also designed to improve the quality of interior air. Building air can be more polluted than outside air as it is composed of human skin particles, microscopic insect droppings, pet dander, pollen, fabric particles and a wide variety of allergens and pollutants. It is important to keep your HVAC system running properly and maintain indoor air health by regularly replacing the air filter with a 3M Filtrete air filter. Several types of filters are available for contemporary HVAC systems, each trapping particles in a slightly different manner. Electrostatic filters rely on static electricity to attract and trap particles. Fiberglass panel filters trap only very large particles and need to be replaced frequently. Pleated air filters work by trapping particles on the surface instead of on the inside, while HEPA filters are a supercharged version of pleated ones.