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What are Air Handling Units?

January 29th, 2016

Blog: If you’ve ever passed under a metal duct, one that forms a part of an HVAC system, you may have heard a mechanical “belch” emanating from its hollow innards. This is nothing more than the pressure differential equalising within a building’s environmental control framework. Air handling units push the air around this metal circuit, driving warm currents into rooms and hallways so that they can circulate and warm the cool space. Generic in terminology, the fan modules are the dynamic stage of a heating ventilation and air conditioning system (HVAC), although the AC section can be omitted, again for the sake of creating a generic climate management network.

System Actuators

The inlet pathways and cooling technology that allows warmth to find its way into a specified area would be next to useless without air handling units. They’re the boxy modular assemblies that contain electrically powered fans and belt drives. The motor turns a belt, and the belt rotates a blower assembly, a mechanical contrivance that assumes a handful of shapes. Axial fans and centrifugal blowers form the heart of the module, but that’s a bit like saying the human body works on heart power. There’s a lot more going on inside the squarish metal chamber than fans blowing air, although this is a core function.

Compact Modular Efficiency

Air handling units substitute passive atmospheric pressure with a dynamic electrically powered wind, true, but many more components are installed in the easy-to-maintain box. Mechanically actuated vents are often located on the inlet and outlet sides of the AHU, as are the filters. The idea is to create a network of ducts that go anywhere in the building, but the handler stays in an accessible location so as to allow quick maintenance. A lockable door with a strong seal is fitted to a man-sized housing. On opening the housing, an engineer can replace filters, adjust fan belts, replace the electric motor, and/or generally maintain the entire HVAC system from an accessible location.

Smaller buildings typically use a few AHU appliances, but large high rise structures and office buildings employ multiple units – appliances that create what’s called a multi-zone HVAC system. From here the fans circulate air and dampers open or close to direct cooling or heating energy. To do this, heating elements and cooling coils are added to the blower stage, creating the full heating, ventilating, and air conditioning experience in a box.




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