Comparison of operation between parallel constant speed fans and variable speed fans

Analyses the fan performance curve and pipe network characteristic curve of parallel fan system and variable speed fan system. The results show that during the operation regulating of parallel fans, valve adjustment is needed to avoid excessive flow and motor overload.  However, it also increases the power consumption and decreases energy saving effect, which is not easy for operation management. During the fan speed control operation, the fan and pipe network can automatically reach the balance without valve adjustment and the energy saving effect is better than parallel fan system.