A commercial air handler is a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. It is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers are usually connected to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the air handler. Commercial air handlers are typically used in larger buildings such as office buildings, warehouses, and schools, and are often connected to multiple air-conditioning units. They are designed to be energy efficient and are capable of providing a comfortable indoor environment for occupants. The main purpose of a commercial air handler is to move air from one place to another, while also providing filtration, heating, cooling, and humidity control.