You can select a dynamic sizing method for the ductwork for the duct systems in a project using the Duct Sizing dialog. You can specify sizing for sections of duct using friction and/or velocity, equal friction, or static regain sizing methods. Sizing can be applied to sections of ductwork or to an entire system.

1. Select a section of ductwork in a view, and click Modify | Ducts tabAnalysis panel Duct/PipeSizing.

Select a Sizing Method

2. In the Duct Sizing dialog, select a sizing method from the drop list: Velocity, Friction, Equal Friction, or Static Regain.

   When you select Friction or Velocity, the following are activated:

   • Only to size ducts according to the parameters for the selected method (Velocity or Friction) exclusively.
   • And to force sizing ducts to meet the parameters that you specify for both Velocity and Friction.
   • Or to allow sizing ducts according to the least restrictive of either the Friction or Velocity parameters.
3. Select a sizing method, and specify the parameter(s) for the selected sizing method(s).

Specify Branch Sizing Constraints

4. You can constrain the size of duct segments by selecting an option from the Constraints list, and specifying an absolute limit on the size of ducts using the Restrict Size option.

   Select one of the following Constraints from the drop list:
   • Calculated Size Only - The size of the selected duct segment(s) is determined by the selected sizing method and is not otherwise constrained.
   • Match Connector Size - The size of the selected duct segment(s) in the branch is determined by the size of the connector used to between the branch and the main, up until the first junction in the network.
   • Larger of Connector and Calculated - The size of the selected duct segment(s) is determined by the larger of 2 determinants. If the connector size is smaller than the size calculated by sizing the sizing method, then the calculated size will be used. If the connector size is larger than the size calculated by sizing the sizing method, then the connector size will be used.
5. If necessary, click Restrict Height/Restrict Width and enter a value to specify an absolute limit to the size of the selected duct segment(s).