When someone points at a massive unit on a ceiling or at the mouth of a tunnel and asks, “What are those huge fans called?”, the answer depends on the setting. In large buildings and warehouses, they are usually called HVLS fans or large industrial axial fans. In tunnels and underground mines, they are typically known as main fans or tunnel ventilation fans. All of them are designed to move large volumes of air rather than the small jets produced by domestic fans.
In warehouses, logistics centres and large workshops, the most visible huge fans are HVLS (high-volume, low-speed) fans. These are very large-diameter axial fans, often 5–7 metres across, mounted on the roof structure. They turn slowly but move a tremendous volume of air, creating a gentle circulation that evens out temperature, improves comfort and supports energy savings from heating and cooling systems. People sometimes call them “big-ass fans” after a well-known brand name, but the generic technical term is HVLS fan.
In industrial plants you may also see large wall-mounted or ducted axial fans. These are simply called large axial fans, industrial ventilation fans or process fans, depending on their role. They can be installed in walls, roofs or ducts to exhaust hot, dusty or contaminated air and to bring in fresh air for workers and equipment.
In tunnels and underground mines, the huge fans at the portal or shaft collar are typically referred to as main fans. They are large axial or centrifugal units designed to move bulk airflow through long roadways and shafts, supplying oxygen, removing fumes and controlling heat. In road tunnels, similar units are called tunnel ventilation fans, which may include long-case axial fans or jet fans mounted along the crown of the tunnel to drive airflow and control smoke in emergencies.
Some process industries and power stations also use huge cooling tower fans. These are large axial fans mounted at the top of cooling towers, drawing air through the fill to remove heat from circulating water. From the ground they appear as big circular openings with fan blades visible when the tower is not running.
So there is no single universal name for every big fan you see. In everyday language we might just say “giant fan” or “huge industrial fan”. More precisely, the most common names are HVLS fan for large building ceiling fans, large axial or centrifugal industrial fan for plant ventilation units, main fan for huge mine fans and tunnel ventilation fan for major tunnel installations. The exact term usually reflects both the fan style and the environment in which it operates.
