- Motor and drive efficiency directly impact on fan energy consumption. The cost of energy over the lifetime of
the motor may be more than twenty times its initial purchase price.
- Ductwork should be designed to avoid interfering with airflow, especially at fan inlets and outlets. Airflow
straighteners may be used to improve airflow.
- Airflow is chiefly controlled by:
Inlet vanes and dampers,
Outlet dampers, and
Fan speed control
- Disc Throttles are used with some centrifugal fans, and variable-pitch blades are an option with some axial
fans.
- Speed control is the most efficient means of controlling airflow.
- Multiple speed motors provide fixed speed settings.
- Adjustable speed drives provide a continuous range of settings.
- Variable Frequency Drives are the most popular type of Adjustable Speed Drive.
Maintenance is essential to avoid the effects of wear and fouling on motors, fans, ductwork, filters and heat exchangers.
Oversized fans may be detected by:
- Excessive noise and vibration
- Frequent maintenance
- Unstable operation
- Vanes and dampers that are normally closed and may be rusted in place, and by
- Low fan load factors
Corrective measures for oversized fans include:
- Replacement with a smaller fan
- Using a more appropriate fan type or an axial fan with controllable pitch blades
- Decreasing fan speed using different sheave sizes
- Adjustable speed commonly using a variable speed drive
- Using multiple fans
For more information contact Mearsecroft