In the world of air handling units (AHUs), the efficient movement of air is paramount to maintaining indoor comfort and air quality. Two common types of fans used in AHUs are forward curving fans and backward curving fans. Each fan type offers unique characteristics and advantages, tailored to specific HVAC applications. Let’s delve into the differences between forward and backward curving fans and their roles within AHUs.
Forward-curving fans:
Forward curving fans, also known as “squirrel cage” fans, are characterised by blades that curve in the direction of the fan’s rotation. These fans typically have a large number of small blades arranged in a radial pattern. When the fan is in operation, air is drawn in axially and then forced outward by the spinning blades.
Advantages of Forward-Curving Fans:
1. Low Noise Levels: Forward curving fans are known for their relatively quiet operation, making them suitable for applications where noise levels need to be minimised, such as in commercial buildings or residential settings.
2. Stable Performance: These fans exhibit stable performance characteristics across a wide range of airflow conditions, ensuring consistent air delivery and pressure within the AHU.
3. Energy Efficiency: Forward curving fans are designed to operate efficiently, requiring less power consumption compared to other fan types while delivering adequate airflow.
Backward-curving fans:
Backward curving fans feature blades that curve against the direction of rotation, resembling a concave shape. These fans typically have fewer, larger blades compared to forward curving fans. As the fan rotates, air is drawn in axially and then redirected by the curved blades, resulting in increased pressure and airflow.
Advantages of Backward Curving Fans:
1. High Efficiency: Backward curving fans are renowned for their high efficiency, particularly in applications where static pressure is a critical factor. The design of the blades allows for optimal airflow performance even at higher pressures.
2. Robust Construction: The construction of backward curving fans, with fewer blades and a sturdy design, makes them durable and capable of withstanding harsh operating conditions.
3. Variable Speed Control: These fans are well-suited for variable speed control, allowing for precise adjustment of airflow rates to meet changing HVAC demands, thereby enhancing energy savings and system performance.
Role of Fans in AHUs:
In an AHU, both forward and backward curving fans play crucial roles in facilitating the movement of air through the system. The fan is responsible for drawing in outside air, conditioning it as necessary (heating or cooling), and then distributing it to various zones or rooms within a building through ductwork.
The selection of fan type (forward or backward curving) depends on factors such as airflow requirements, static pressure considerations, energy efficiency goals, and noise constraints. By choosing the appropriate fan type and optimising its operation within the AHU, HVAC engineers can ensure efficient airflow delivery, maintain comfort levels, and minimise energy consumption.
Conclusion:
In conclusion, forward curving fans and backward curving fans each offer distinct advantages and are tailored to specific requirements within AHUs. Whether prioritising low noise levels, stable performance, high efficiency, or variable speed control, there is a fan type suited to meet the needs of diverse HVAC applications. By understanding the differences between forward and backward curving fans and their roles within AHUs, HVAC professionals can make informed decisions to optimise airflow, enhance system performance, and ultimately contribute to comfortable and healthy indoor environments.
If you want to learn more about HVAC and Air Handling Units, feel free to send us an email at info@bvs-ltd.co.uk or give us a call 01256 518170 and we’d be more than happy to help.