An upblast fan is a type of exhaust fan that discharges air vertically upward above the roof line. It is usually mounted on a roof curb and designed so that contaminated air, heat, fumes or grease are thrown away from the roof surface and building openings. Upblast fans are common in commercial kitchens, industrial process areas and any application where exhaust must be directed safely away from the building.
Most upblast fans are centrifugal designs with a weatherproof housing. Air enters from below, passes through the rotating wheel and is discharged through a bell-shaped outlet that directs the flow upward. The housing is shaped to protect the motor and internal components from rain, snow and wind. In kitchen exhaust duty, the fan may include a grease collection system and easy-access hinges so that the unit can be tipped back for cleaning.
The purpose of the upblast arrangement is to manage where exhaust air goes. By throwing the air vertically and at high velocity, the fan helps keep hot, greasy or odorous air from staining the roof surface or being drawn back into nearby air intakes or windows. In industrial service, upblast fans may handle process fumes, light dust or hot air from ovens and dryers, discharging them to the atmosphere at a safe height.
When selecting an upblast fan, engineers consider air volume, static pressure, temperature and contaminants. Kitchen and grease-laden airstreams require special construction and certifications. High-temperature applications, such as smoke control systems, may require fans tested to operate at elevated temperatures for a specified time. Materials, coatings and motor enclosures are chosen to suit outdoor conditions and the chemistry of the exhaust.
Upblast fans fit into the overall ventilation strategy of a building or plant. They work together with supply air systems, make-up air units and general ventilation so that the exhausted air is replaced with fresh air and building pressure remains under control. In facilities associated with mining—such as workshops, processing plants or laboratories—upblast fans may be used where localized exhaust to the roof is the best solution.
In summary, an upblast fan is a roof-mounted exhaust fan that directs air vertically away from the building, helping to remove heat, fumes, grease or smoke safely and protect roof surfaces and nearby air intakes.
