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<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2>Dear Bill,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2>I don't think I follow your logic. If the
<U>total</U> plant head (primary plus secondary) is ~100 ft., and assuming
that water flow is about the same for both primary and secondary, then your
calcs indicate that 22W is a reasonable number for the pumping system
efficiency.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2>This is essentially the same scenario that I intended
to use below. The primary side would use, say, 30ft of head and the
secondary side would use ~70ft. If the total head is greater than that, it
(obviously) becomes tougher to comply with 22W / gpm.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=937340901-09012009><FONT face=Arial
color=#0000ff size=2>That said, I haven't modeled a System #7 or 8 per Appendix
G yet, so I'm just hypothesizing!</FONT></SPAN></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><SPAN class=937340901-09012009><FONT face=Arial color=#0000ff
size=2>p.s., <SPAN class=937340901-09012009><FONT face=Arial color=#0000ff
size=2>I think it will be tough to get a combined wire-water efficiency of
85%!</FONT></SPAN></FONT></SPAN></DIV>
<DIV class=Section1>
<P class=MsoNormal style="TEXT-ALIGN: center" align=center><B
style="mso-bidi-font-weight: normal"><FONT size=4>The Building Performance
Team<BR></FONT></B><B style="mso-bidi-font-weight: normal">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" /><o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P></DIV>
<DIV> </DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> William Bahnfleth
[mailto:wbahnfleth@psu.edu] <BR><B>Sent:</B> Thursday, January 08, 2009 7:52
PM<BR><B>To:</B> James V. Dirkes II P.E.; xiaodongyi@hotmail.com;
bldg-sim@lists.onebuilding.org<BR><B>Subject:</B> Re: [Bldg-sim] chilled water
pump power<BR></FONT><BR></DIV>
<DIV></DIV>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 class=cite cite="" type="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>
<HR>
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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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