Dear Camilo,
You will need to model the pump as though it is a variable speed pump, and use a power vs flow curve similar to what I develop in the attached file. Although it is actually a constant speed pump, it is not constant flow or constant power. Therefore, E+ must treat it as variable speed. The power curve results in calculation of the appropriate power for flow variations.
The curve object is as shown below.
Curve:Quadratic
Name
Curve_PumpPower1,
Coeff1 Constant
0,
Coeff2 x
1.339155,
Coeff3 x**2
-0.330745,
minimum value of x
0,
maximum value of x
1;
Minimum Curve Output
Maximum Curve Output
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of caveleza
Sent: Wednesday, November 16, 2011 1:02 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Pumps: riding the curve
Hello Everybody!
I'm modeling a building following ASHRAE 90.1 Appdx G, but i have a problem regarding primary/secondary pumps loop...
According to appendix G (G3.1.3.10):
"Chilled water
pumps in systems with less than 300 tons
cooling capacity shall be modeled as
primary/secondary systems with
secondary pump riding the pump curve."
I know that the secondary pump (in this case) must be a constant speed pump (just like the primary), but as they want that it "rides the curve" the loop should have an arrangement of two-way or a three-way valves, but i'm not sure of this or how to do it in energyplus. Anyone has the same problem?? Any help will be appreciated!!
Thanks!
Camilo.
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