Inline duct fans — direct duct mounting for compact, quiet ventilation installations

An inline fan is the solution for ventilation installations where the fan must be concealed — mounted inside the duct run, in a suspended ceiling or in a plant room — and not visible on a wall or roof. Unlike wall fans requiring an opening in the exterior wall, an inline fan mounts directly onto the circular duct at any point along the run and can be positioned wherever installation and maintenance access is available.

Constructive types: Mixed Flow axial inline fans combine the axial principle (airflow parallel to the rotor axis) with a centrifugal component introduced by blade geometry. The result is a fan capable of generating higher static pressure than a pure axial fan at the same noise level — enabling correct operation in installations with medium-length duct networks, not only in direct extractions without resistance. The Vent-Axia ACM series is the reference example: compact, extremely quiet (below 35 dB(A) at nominal airflow), with integrated STOP thermal overload protection, horizontal and vertical operation, ambient temperature up to +50°C. Centrifugal inline fans offer higher static pressure than axial inline fans, for longer duct runs or those with more accessories (bends, grilles, filters). Ideal for multi-room extraction on a single duct trunk or VMC installations with more complex distribution networks.

When to choose an inline fan over a wall fan: the room may be far from an exterior wall (interior office, bathroom without exterior wall, commercial space with glazed facades), aesthetics do not allow a visible opening on the facade, or multiple rooms must be ventilated simultaneously on a single duct run with a single fan. Inline fans mount on circular ductwork using clamp brackets or screws after cutting the duct to the fan flange dimension. Optimal positioning is on a horizontal run, though Mixed Flow models also operate vertically. Typical applications: bathroom and kitchen extraction through ceiling-concealed ductwork; commercial space ventilation without available exterior wall; VMC systems with multi-room distribution; corridor and circulation space ventilation; filtered fresh air supply to bedrooms and offices.