Clarification

[premhvac]

how do calculate the pressure drop in Vertical 20 meter duct and horizontal 30 meter duct

[The Viking]

There are various calculations you will need to do based on volumes, velocities, cross sectional areas and so on. If it is vertical or horizontal doesn't come in to it.

To aid with this complicated task there are various software packages available, some of which are free. Try searching the web for "ductulator", that used to be pretty good and easy to use as well as free but I don't know if it still is around

:cool:

[Peter_1]

If it's horizontal or vertical, that's not important. Speed, roughness of the duct, branches, elbows, flow,...that's important