Forward Curved Vs Backward Curved Centrifugal Fan Efficiency

The most common hvac fans are axial forward curved centrifugal and backward inclined and each is uniquely suited to certain purposes.

Forward curved vs backward curved centrifugal fan efficiency.

It s important to understand each fan s differences in energy efficiency cost effectiveness and noise considerations. Another important design feature is the position of the motor. Do not rate fan in the pressure curve dip to the left of peak pressure. Do not rate fan in the pressure curve dip to the left of peak pressure.

The optimum operating area for a forward curved centrifugal fan is when it is operating at higher pressure. Motor selection must take this into account. The modern forward curved blades are designed with a scroll housing. The non overloading characteristic the ability to install the fan with or without a scroll and an impeller design that offers the highest static efficiency of all types of fans means that the backward curved fan is a flexible adaptable fan design can be used across a wide range of installations.

Backward curved centrifugal fans. Forward curved fan. In most cases these fans are designed with external motors. Backward inclined the performance of the backward inclined wheel is similar to the forward curve however bi fans tend to be non overloading meaning their fan curves do not tend to increase hp as static pressure changes but cfm falls off.

As with the backward curved centrifugal fan the suction side of the impeller blade draws air from the centre of the fan which results in a directional change of the airflow between the inlet and the exhaust of 90 o. Power rises continually toward free delivery. Flatter pressure curve and lower efficiency than the airfoil backward curved and backward inclined. Motor selection must take this into account.

Flatter pressure curve and lower efficiency than the airfoil fan backward curved fan and backward inclined fan. Power rises continually toward free delivery. Pressure curve less steep than that of backward curved. On the other hand those with backward curved blades are basically free wheeling fans.