A high-volume low-speed (HVLS) fan is a type of mechanical fan used in commercial and industrial settings. HVLS fans are generally ceiling fans although some come as pole mounted fans. Unlike residential ceiling fans that are typically 36- to 52-inches in diameter, HVLS fans have very large diameters that start at 8-feet and go up to 24-feet. HVLS fans move very slowly unlike standard fans which operate at high speed. With such large diameters, HVLS fans can move large amounts of air at low rotational speed– hence the name "high volume, low speed."
HVLS commercial ceiling fans can be found in livestock barns, warehouses, distribution centers, shopping malls, skating rinks and health clubs. Due to the rising costs of energy, HVLS fans are often used to supplement HVAC systems as they provide a stronger cooling effect while helping to maintain a constant temperature and humidity.
HVLS fans work on the principle that a breeze moving across your skin on a very hot day feels good. The cool moving air breaks up the moisture-saturated boundary layer surrounding the body and accelerates evaporation to produce a cooling effect.
No matter their size, ceiling fans produce a column of air as they turn. This column of air moves down and out along the floor. Called a horizontal floor jet, this deep wall of horizontal moving air is relative to the diameter of a fan, and to a lesser degree, the speed of a fan. Once the floor jet reaches its potential, it migrates outward until it meets a side wall or other vertical surface.
Under ideal conditions, an 8-foot fan produces a floor jet of air approximately 36 inches deep. A 24-foot fan produces a floor jet 108 inches deep, tall enough to engulf a human standing on the floor or a cow, its initial development purpose.
HVLS fans incorporate a motor, hub, and aluminum fins or blades. Commercial HVLS fans differ from residential ceiling fans with regard to diameter, rotational speed, and performance.