DA-88-18-4 -- Decoupling Supply and Return Fans for Increased Stability of VAV Systems PDF

There are many problems associated with the control of typical supply and return fan VAV systems. The principal problems with these systems are the coupling of many variables affecting the supply and return fans and deficiencies in the control algorithms being used. DDC control systems can times and fan turn-down also contribute to the control problems. Due to these conditions, the control strategies typically used have been unable to achieve reasonable system stability. An alternative control strategy can be used to correct the deficiencies in the standard algorithm and decouple the interaction of the supply and return fan to achieve system stability.

Units: I-P