Adrian,
Actual data is probably better, but consider:
· It’s not likely that one VSD pump will be too much different than another, or too much differently than ASHRAE’s “typical” VSD pump
o Most pumps work similarly and with similar (VSD) efficiency
o Very large or specialty pumps might be significantly different!
· If you want to create a specific curve for your pump(s), go right ahead by using the manufacturer data (pump and VSD)
o Most VSDs lose a small amount of energy within the electronics, so you should include that energy (I use ~2%)
· It might be interesting and illuminative to compare the energy for an ASHRAE typical pump with specific pump data
o I have not felt that it was worth the extra time to create specific pump coefficients because all the pumps I’ve modeled were standard VSD pump applications or very small specialty pumps
o Some of the new ECM motor pumps, however, may be worth the effort � but I have not had a project with one of those yet
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of adrianchong85@xxxxxxxxx
Sent: Wednesday, January 08, 2014 3:42 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Cubic Curve in variable speed pump
Jim,
Thanks for replying. Why do you propose the use of coefficients from 90.1? Wouldn't coefficients derived from the pump's performance curves count as actual data? and thus be a better representation?
Regards,
Adrian
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