Twinflow STDR400-1EC

Direct Drive Twin Centrifugal Fan

  • Standard size 400 mm
  • Air volume flow rates up to 0.962 m3/s
  • Static pressures up to 868 Pa
  • Suitable for operating temperatures up to +60℃
  • Available in EC


The Twinflow STDR fans are suitable for external mounting, manufactured in Aluzinc with a natural finish and fitted with advanced centrifugal impellers.

Features and Benefits

Easy Installation

All models are designed for direct connection to standard diameter flexible or rigid circular ducting with long spigots. Spigot is on the underside of the unit and can be fitted directly to the main duct.

Easy Commissioning

Integrated commissioning control allows single speed selection and also limits maximum speed if used with an external potentiometer.

Space Saving

External roof mounting is ideal where space is a premium. Bird guard fitted as standard to stop damage by wildlife.

Efficient Performance

High efficiency low tonal noise backward curved centrifugal impellers are directly driven by an EC external rotor motor, provide low specific fan powers and stepless speed control without tonal noise generation.

Weather Resistance

Integral louvered air discharge provides protection against ingress from the elements and is self draining. No additional outlet duct fittings are required. The unit has back draft shutters fitted as standard.

Twin Fan Operation

Allowing control for auto changeover and duty share.


EC motors providing precise speed control via potentiometer, BMS or Elta Fans DCV control. Reduced fan speed can provide significant cost-savings through lower energy consumption in both mechanical energy of motors and also on the conditioning of replacement air.


Each STDR has a 12 month warranty.



The unit casing shall be manufactured from 1.2mm thick natural finish Aluzinc. The casing shall be designed so as to minimise vibration and shall incorporate a louvered air discharge guarded against bird ingress. Backdraught shutters shall be fitted as standard. Each casing provides an inlet spigot to suit standard circular ducting. Top access panels shall be provided for ease of servicing.


The Twin range of units shall have EC external rotor motors fitted as standard. The motors contain sealed for life bearings. Thermal Class of motors to THCL 130 or 155 dependent on size. All motors are suitable for use in ambient air conditions up to +60 ℃.


High efficiency low tonal noise backward curved centrifugal impeller, dynamically balanced to ISO 14694 Grade G6.3 and directly driven by the motor to provide a smooth airflow through the unit.


Units shall be supplied with integrated commissioning control allowing single speed selection and also limiting maximum speed if used with an external potentiometer. Speed control shall be via external potentiometer or 0-10V, Auto changeover in the event of fan fail or duty share of run and standby fan shall be via auto changeover panel.

Quality Management

Units are to be designed and manufactured with procedures as defined in BS EN ISO 9001. All Twinflow STDR units are to be tested to ISO 5801 (airside performance) and BS 848 Part 2 (sound performance).

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