Filter
Top Products
38 TRG-TRC014-EN
notes
period two
Components of a VAV System
Designers commonly use two methods to engineer the supply duct system:
n Equal friction
n Static regain
Equal friction duct systems are designed for an equal static-pressure drop per
foot of duct. This results in a static pressure that is very high near the fan, and
which steadily decreases until it is very low near the far terminal units. Equal
friction duct systems can be easily designed by hand.
Static regain duct systems strive to maintain a fairly consistent static pressure
throughout the entire duct. Therefore, for VAV systems, the static regain
method is recommended for sizing the supply ducts upstream of the terminal
units. This relatively constant static pressure at the terminal unit inlet allows for
improved selection and control. The design of a static regain duct system often
requires the use of a computer program.
Duct Design
▲ Equal friction method
◆ Equal static pressure drop per unit length of duct
◆ Design can be performed by hand
▲ Static regain method
◆ Relatively constant static pressure throughout system
◆ Desirable for VAV system duct design
◆ Design often requires a computer program
Figure 53