External Static Pressure Calculations

[angellore]

hello everyone and thank you all .. this forum helped me alot ... and this is my first post.

sometimes and sadly there is no time to make a proper ESP calculation, if using the regular constant fiction method for duct sizing ... what would be the disadvanages of oversizing the external static pressure of the AHU fan ?

thank you.
Shadi

[DTLarca]

hello everyone and thank you all .. this forum helped me alot ... and this is my first post.

sometimes and sadly there is no time to make a proper ESP calculation, if using the regular constant fiction method for duct sizing ... what would be the disadvanages of oversizing the external static pressure of the AHU fan ?

thank you.
Shadi

Slap an inverter drive on the fans and ramp them down as needed - job done.

[Brian_UK]

Disadvantage would be excessive energy usage.

[Magoo]

Are you talking about trunk duct design, static re-gain method.

[DTLarca]

Are you talking about trunk duct design, static re-gain method.

He's talking about a constant friction method - not high velocity systems with velocity to static conversion after each take-off (static regain).

[Sridhar1312]

Both in AHU and pumps excess static and head in pumps is always an issue not given due importance consequently energy wastage. Ideally as soon as commissioned the Air quantity shall be measured and if need be pulley of motor is changed along with belts so as to deliver closer to design air quantity so that the system will be effective. Then adding VFD will save further power .