To Specify a Calculation Method for Duct Sizing

1. In the HVAC workspace, click Manage tabStyle & Display panelStyle Manager drop-downHVAC System Definitions.
2. In the Style Manager, select a duct system under Duct System Definitions.
3. In the right pane of Style Manager, select the Design Parameters tab.
   

4. Specify which method to use to calculate duct sizes:

   To…	then…
   use the constant velocity method	select Velocity, and enter a value.
   use the equal friction method	select Friction, and enter a value.

   Note: The Add Duct dialog box displays the fixed parameter value with an asterisk (*). The fixed parameter value initially calculates the exact duct size, and is then used to specify an available size in the catalog. Once you calculate duct size, the fixed parameter value in the Add or Modify dialogs might differ from what is specified in Design Parameters. See Duct Sizing Methods and Tools for more information.
5. Specify a value for Roughness (roughness value of the ductwork material).
6. Specify a value for Density (medium used in the system, for example — air).

   The initial default value is the density of air at sea level at 68 degrees F (20 degrees C).

7. Continue specifying the design parameters for other duct systems, and click OK.