You have used Design Master HVAC to size ductwork using the constant pressure drop and constant velocity methods, but have you used the static regain calculation in our software?
Static regain is the third sizing method for ductwork included in Design Master HVAC. It is most often used in the high pressure ductwork between the main AHU and the VAV boxes.
The calculation works by keeping the static pressure in the ductwork constant throughout the system. The air velocity is decreased so that the velocity pressure drop matches the total pressure drop in the system. Sizing ductwork using the static regain method results in small ducts and a system that is nearly balanced when first installed.