DWDI double inlet centrifugal fans — DD and DDM Nicotra Gebhardt series for professional hoods, AHUs and HVAC systems

Double inlet centrifugal fans (DWDI — Double Width Double Inlet) are a distinct category from standard single-inlet centrifugal fans. The DWDI construction means the impeller draws air simultaneously through both lateral faces — left and right — instead of a single face. This geometry is the foundation of the technical and economic advantages of the range.

Why DWDI instead of single-inlet for the same application:

At the same motor power, a DWDI fan delivers 30–40% more airflow than its single-inlet equivalent — because the active intake area is doubled. Alternatively: for the same airflow, the DWDI motor can be 25–30% smaller, consuming less and generating less noise. Additionally, axial forces on the impeller balance each other from both intake directions — bearings are less stressed and fan service life increases significantly.

DD Series — Nicotra Gebhardt, direct drive, internal rotor:

Galvanised steel EN 10142 casing assembled by overlap-seam rolling. Galvanised steel impeller with forward-curved blades, mounted directly on the motor shaft — completely eliminating belts, pulleys and transmission bearings. Zero mechanical transmission losses, zero transmission maintenance. Single-phase IP44 or three-phase motor, with integrated thermal protection, integrated anti-vibration isolators and self-aligning sleeve bearings. Dynamically balanced to ISO 1940.

The DD range covers sizes from DD 7/7 (~1,800 m³/h) to DD 12/12 (~7,000 m³/h) and above, in single-phase 230V and three-phase 400V versions — the only DWDI range on the Romanian market available in single-phase for applications without three-phase supply.

DDM Series — Nicotra Gebhardt, External Rotor Motor (ERM):

Identical construction to DD but with ERM (External Rotor Motor) — the motor and impeller form a unitary assembly where the stator winding is internal and the electromagnetic rotor rotates externally, directly on the shaft carrying the fan impeller. ERM advantages over conventional motor: more efficient motor cooling (fan impeller directly cools the motor), more compact dimensions, IP55, superior energy efficiency. Available single-phase and three-phase, from DDM 7/7 to DDM 280/204 and above.

DDMP Series — EC motor with permanent magnets:

The EC motor (brushless, permanent magnets) version of the DWDI range — maximum efficiency, precise speed control via 0-10V signal, energy consumption 30–50% lower than AC motor at partial loads. The solution for AHUs with strict energy efficiency requirements (nZEB, certified energy-class buildings).

Insulated plenum box option: Any model can be supplied integrated in an insulated plenum box — aluminium profile structure with galvanised or RAL 9010 painted panels, with 6 mm or 10 mm polyurethane insulation. Used when the fan is installed in a plant room where noise must be reduced or when it forms part of a professionally insulated kitchen hood.

Plug & play option: The fan can be supplied as a plug & play unit — ready to operate, equipped with a complete speed control kit for easy airflow adjustment. Eliminates the need to separately procure and integrate the speed controller.

Main applications:

• Large professional hoods — restaurants over 100 covers, hotels, hospitals, industrial canteens
• AHUs (air handling units) for commercial and industrial buildings — fan mounts directly in the unit plenum
• HVAC systems for offices, shopping centres, hotels — high airflow at low noise levels
• Direct replacement of worn motors on existing Nicotra Gebhardt hoods and AHUs

👉 CF HP external motor kitchen hood fans — for medium hoods 👉 Airflow calculator

📞 +40 722 667 239 — free consultancy for choosing the correct size based on required airflow and static pressure