Hydronic Pipe Sizing Methods

Revit provides 2 standard sizing methods for sizing pipe:

Options in the Pipe Sizing dialog let you select either method by itself (select Only) or in combination with the other (select And or Or).

Sizing Method - Friction

Sizing Method - Velocity

If you select And, the size of the pipe must comply with both the Friction and Velocity values. If you select Or, the size of the pipe must only comply with one of these rules. The following curves show the difference between using the Or and And options:

Friction () And Velocity () Pipe Sizing Method

Friction () Or Velocity () Pipe Sizing Method

How Velocity Affects Noise and Erosion

Velocity can be increased if the hours of operation are reduced and the erosion criteria will remain based on the following table.

Hours (per year) Velocity (fps)
1500 1
2000 14
3000 13
4000 10
6000 Junction