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I sincerely doubt it.<br><br>
A fairly typical total pump head for plant and distribution for a
primary/secondary systems might be 100 -120 ft. (Note, I am not
saying that is GOOD practice, but it is typical. One can generally
do better.)<br><br>
Let's say that the overall efficiency of pump, motor, and drive is
~85%.<br><br>
If we use the common engineering approximation HP = (Q*H)/(3960*eta_t),
and given that 1 HP = 745.7 W, the power associated with 1 gpm and
100 ft wg head is<br><br>
W = 745.7*(1*100)/(3960*0.85) = 22.15<br><br>
I cannot think of a reasonable scenario under which 44 W/gpm could be
construed to represent minimally acceptable practice.<br><br>
Bill Bahnfleth<br><br>
At 07:14 PM 1/8/2009, James V. Dirkes II P.E. wrote:<br>
<blockquote type=cite class=cite cite=""><font color="#0000FF">Good
question! My guess is that each pump may be 22W / gpm. Since
they are required to use variable speed drives (for >300T), it won't
affect energy adversely.<br>
</font> <br>
<font color="#0000FF">There may be an ASHRAE clarification on this topic;
have you checked with them?<br>
</font> <br><br>
<div align="center"><font size=4><b>The Building Performance Team<br>
</font>James V. Dirkes II, P.E., LEED AP<br>
</b>1631 Acacia Drive NW<br>
Grand Rapids, MI 49504<br>
616 450 8653<?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" /><br>
</div>
<br>
<br>
<br><br>
<hr>
<font face="Tahoma" size=2><b>From:</b>
bldg-sim-bounces@lists.onebuilding.org
[<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" eudora="autourl">
mailto:bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of
</b>xiao dongyi<br>
<b>Sent:</b> Thursday, January 08, 2009 6:18 PM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] chilled water pump power<br>
</font><br>
Hi,<br>
<br>
I have a question regarding the chilled water pump power calculation in
ASHRAE 90.1 Appendix G:<br>
<br>
ASHRAE 90.1 Appendix G Paragraph G3.1.3.10 requires that "The
<i>baseline building design </i>pump power shall be 22 W/gpm<i>.".
</i>If the chilled water pumping system is a primary-secondary system,
how does this rule apply? i.e. does the 22 W/gpm apply to the primary
pump, secondary pump, or both? Or, do I need to divide it between the
primary and secondary pump?<br>
<br>
Your suggestions will be greatly appreciated.<br>
<br>
Thanks,<br>
<br>
Dongyi<br><br>
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<div>__________</div>
<br>
<div>William P. Bahnfleth, PhD, PE, FASHRAE</div>
<div>Professor of Architectural Engineering and Director, Indoor
Environment Center</div>
<br>
<div>Penn State / 104 Engineering Unit A / University Park, PA 16802
USA</div>
<div>voice: 814.863.2076 / fax: 814.863.4789 / e-mail:
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