DWDI forward-curved EC motor fans — high-airflow double-inlet centrifugal for AHU integration

DWDI — Double Width Double Inlet — fans with forward-curved blades and EC motor are the high-performance solution for air handling units requiring high airflows in a compact footprint. DWDI means double inlet: the rotor has two inlet openings, one on each side of the casing, which effectively doubles the admission area compared to a single-inlet rotor of the same diameter — delivering significantly higher airflows with the same motor footprint.

Forward-curved blades: the blades are oriented in the direction of rotation. This geometry generates the highest airflow at the lowest speed of all centrifugal blade configurations — a major advantage in AHUs where noise levels must be minimised (lower speed means lower noise). The disadvantage compared to backward-curved blades: motor power is not self-limiting — at high airflows or low pressures, the motor can overload if not sized with margin. This is precisely why precise EC motor speed control is essential in this configuration.

The integrated EC motor solves exactly this problem: continuous speed control via 0-10V or Modbus RS485 signal allows permanent operation at the optimal operating point, preventing overload and ensuring maximum efficiency at any operating condition. The driver mounted directly on the casing — plug-and-play solution — eliminates complex wiring and reduces AHU integration time.

Typical applications: medium-to-large commercial and industrial AHUs (airflows 2,000–20,000 m³/h), ventilation plants for hotels, hospitals and shopping centres, variable airflow (VAV) systems where continuous speed control is standard, industrial air coolers and any application where high airflow in a compact footprint takes priority.

Difference from Plug: DWDI fans include their own spiral casing — they are not mounted in a plenum like Plug fans, but are complete units with bilateral lateral inlet and discharge through a single outlet.

How to choose: verify required airflow and static pressure, available casing dimensions in the AHU and EC driver supply voltage. Consult manufacturer performance curves — forward-curved blades have flatter airflow-pressure characteristics than backward-curved, making them more tolerant of resistance variations.

👉 Plug backward curved EC motor — single inlet, plenum design 👉 DWDI backward curved EC motor — double inlet, superior efficiency