The air handler, also known as the air handling unit (AHU), is a crucial component of a heating, ventilation, and air conditioning (HVAC) system. It is responsible for circulating conditioned air throughout a building or home. Here's an overview of what the air handler does and its key functions: Air Circulation: The primary function of the air handler is to circulate air within the HVAC system. It pulls in air from the return ducts, passes it through the system for conditioning, and then distributes it back into the living or working space through the supply ducts. Conditioning Air: The air handler conditions the air by passing it through various components, including filters, heat exchangers, humidifiers, dehumidifiers, and cooling coils. These components help remove impurities, control temperature, humidity, and improve indoor air quality before delivering the conditioned air to different areas of the building. Filtration: The air handler often includes filters that capture dust, pollen, pet dander, and other particles from the air. These filters help improve indoor air quality by reducing airborne allergens and pollutants. Regular filter maintenance and replacement are important for optimal performance. Heating and Cooling: In HVAC systems with both heating and cooling capabilities, the air handler plays a vital role in the process. During the cooling mode, the air handler passes the indoor air over chilled coils, removing heat from the air and lowering its temperature. In the heating mode, the air handler passes the air over heated coils or a heat exchanger, raising the temperature before distributing it. Fan Operation: The air handler contains a fan or blower that helps move the air throughout the HVAC system. The fan draws in air from the return ducts, forces it through the conditioning components, and then pushes the conditioned air back into the living or working space through the supply ducts. Control and Distribution: The air handler is controlled by a thermostat or a building automation system. It responds to temperature and humidity settings to maintain a comfortable indoor environment. It also ensures that the conditioned air is distributed evenly to different zones or rooms within the building. Overall, the air handler acts as the central hub for conditioning and distributing air in an HVAC system, playing a critical role in maintaining indoor comfort and air quality.