Air handlers are an important component to any HVAC system. Usually, an air handler is a large metal box containing a blower, heating and/or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork that distributes the conditioned air through the home, and returns it to the air handler. Sometimes air handlers discharge and admit air directly to and from the space served, without necessary ductwork.
An air handler is usually located in the garage, a closet, or in the attic unless it is part of a package unit, then the air handler is incorporated in the system. The air handler can be an up flow air handler, down flow air handler, or horizontal flow air handling unit.