The first thing to investigate is whether the fan only provides day-to-day ventilation or also has a smoke extraction role in the event of fire. On fans that are part of the smoke mode, the motor belongs to a fan–motor unit documented to run for a set time at high temperature, and replacing it with a standard motor may invalidate the system's approval. Once this has been established, information on the speed arrangement, direction and mounting is gathered.

DRG-100L1-4 2.2 kW 1500 rpm cast iron frame DRG three-phase motor – car park fan motor replacement

Verify the fan's duty from the documentation

If the fan nameplate shows a temperature–time class, the project drawings mention smoke exhaust, or the fire scenario assigns a task to this fan, the motor must be replaced by the installation's authorised contractor with the approval of the fan manufacturer. DRG's standard three-phase motors can be considered for normal ventilation duties; they are not recommended for a fan expected to operate in smoke mode.

Speed, direction and control arrangement

  • Two-speed: Some car park fans have low- and high-speed windings. The models in DRG's list are single-speed; on such a fan, a single-speed motor changes the control scenario.
  • Two-directional: Jet fans can be set up to push air in both directions; it must be confirmed that the motor will perform the same duty in reverse rotation as well.
  • Drive: If there is inverter control linked to a CO sensor, the use of the motor with this drive and the drive settings should be reviewed.

Mechanical information

In jet fans the motor is usually fitted inside a cylindrical casing, either flange-mounted or foot-mounted, with the impeller fixed directly on the shaft. The frame size, shaft diameter and length, flange type and overall length of the new model must fit inside the casing. On ceiling-suspended fans, the condition of the anti-vibration mounts and the balance of the impeller should be checked during the replacement.

To avoid missing information, a photo of the old motor's nameplate, the fan nameplate and the project documentation should be assessed together.

Thrust, two-way operation and motor power are covered on the car park jet fan motors page, while the difference between normal ventilation and smoke mode is explained on the smoke extraction fan motors page. If a normal ventilation duty has been confirmed, you can compare three-phase motor models.