The basic difference between ducts and vents is that ducts are the hidden passages that carry air, while vents are the visible openings where air enters or leaves rooms, ducts, equipment or large spaces. Together, ducts and vents form the distribution network that connects fans and air-handling units to the areas that need ventilation in homes, factories and mines.
Ducts are enclosed pathways—usually made of sheet metal, plastic, fabric or insulated panels—that transport air from one place to another. In building HVAC systems, supply ducts carry conditioned air from the air handler to various rooms, and return ducts bring room air back for filtration and temperature control. In industrial plants, ducts connect local exhaust hoods to dust collectors, scrubbers and exhaust fans. In mines and tunnels, ventilation ducts or airways carry fresh air to headings and return contaminated air to main fans.
Vents are the end points or intermediate openings of this duct network. Inside buildings, vents appear as grilles, registers or diffusers on walls, ceilings or floors. They allow air from the duct to blow into a room (supply vents) or allow room air to be drawn back into the duct (return or exhaust vents). Outside the building, vents may look like louvers or hoods where ducts pass through walls or roofs to the outdoors.
From a functional point of view, ducts determine where the air can flow and how much resistance it meets, while vents determine how air enters and leaves a particular space. Poorly sized or badly arranged ducts increase pressure drop and force fans to work harder, using more energy. Poorly positioned vents can cause drafts, dead zones or ineffective contaminant capture, even if the ducts and fans are correctly sized.
In industrial and mining ventilation, the term airway is often used for large passages that act like ducts but are formed by tunnels, roadways or shafts rather than manufactured duct sections. Openings to these airways—such as stoppings, regulators and louvers—play a similar role to vents in buildings, controlling how air moves between different parts of the mine.
In summary, ducts are the transport pipes of a ventilation system, mostly hidden in ceilings, walls or underground, and vents are the visible openings where air enters or leaves spaces. Both must be designed together with fans and air-handling equipment to create an effective, efficient ventilation system for industrial plants and mines.
