An assembly of components for the treatment of air, controlling its temperature, humidity, cleanliness, and distribution within an air-conditioned space. Types of systems differ, but the basic components may include: outside-air intake, preheater, returnair intake, filters, dehumidifier, heating coil, humidifier, fans, ductwork, air outlets, air terminals, refrigeration machine, piping, pumps, and water or brine. See heating, ventilating, and airconditioning system.