An air handler, or air handling unit, is a device used to condition and circulate air as part of a heating, ventilating, and air conditioning (HVAC) system. An air handler is usually a larger metal box containing a blower, heating or cooling elements filter racks or chamber, sound attenuators, and dampers. Air handlers usually connect to a duct work ventilation system that distributes the conditioned air through the building and returns it to the AHU.
 
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