An Air Handling Unit (AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork.
VRV (Variable Refrigerant Volume) and VRF (Variable Refrigerant Flow) are innovative climate control technologies that allow for changes in temperature in different parts of a building at different times of day. The basic idea is that a large outdoor unit serves multiple indoor units.
The packaged air conditioners are used for the cooling capacities in between these two extremes. The packaged air conditioners are available in the fixed rated capacities of 3, 5, 7, 10 and 15 tons. These units are used commonly in places like restaurants, super markets, houses, small halls, etc.