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<DIV><SPAN class=200395816-18042003>Joe,</SPAN></DIV>
<DIV><SPAN class=200395816-18042003></SPAN> </DIV>
<DIV><SPAN class=200395816-18042003>First, I am not sure which version of the
program you are using. It sounds like DOE-2.2, but could be JJ Hirsch
level 100+ of DOE-2.1E. Are you using the eQUEST or PowerDOE
interfaces?</SPAN></DIV>
<DIV><SPAN class=200395816-18042003></SPAN> </DIV>
<DIV><SPAN class=200395816-18042003>The primary/secondary loops routine of DOE
actually does consider flow and will not allow a secondary flow greater than the
primary flow, so runs the chillers run in parallel to provide sufficient
flow. While a real life primary/secondary system can have higher secondary
flow, it is unusual and not normally what you want. If you use two way
valves on the secondary loop, you can run a single chiller for some hours.
My experience is that you can do that less than you would initially expect, but
if you think it through, the DOE model will give you results closer to real life
than earlier programs that just do a BTU calculation on the cooling
requirements.</SPAN></DIV>
<DIV><SPAN class=200395816-18042003></SPAN> </DIV>
<DIV><SPAN class=200395816-18042003>Let me know if you need to go further with
this.</SPAN></DIV>
<DIV><SPAN class=200395816-18042003></SPAN> </DIV>
<DIV><SPAN class=200395816-18042003>Mike Roberts</SPAN></DIV>
<DIV><SPAN class=200395816-18042003></SPAN> </DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> postman@gard.com
[mailto:postman@gard.com]<B>On Behalf Of </B>Joe Hager<BR><B>Sent:</B> Friday,
April 18, 2003 10:48 AM<BR><B>To:</B> bldg-sim@gard.com<BR><B>Subject:</B>
[bldg-sim] Chiller Staging<BR><BR></FONT></DIV>
<DIV>Hello,</DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV>In DOE-2 I am having trouble with chiller staging. </DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV>System Description</DIV>
<DIV>I have a simplified model that has four zones, two cooled by DX units and
two with chilled water coils. I have a primary chiller water
loop with two 500 ton (6 MBtu/h) chillers and two constant speed primary
chilled water pumps. On the secondary chilled water loop I have a
variable speed secondary chilled water pump and the two zone cooling coils
(with two way valves). I have created an Equipment Control sequence
that has the first chiller running to loads through 4.5 MBtu/h and then
both chillers running to loads through 999 MBtu/h.</DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV>When I run the model I am getting this warning:</DIV>
<DIV>
<P class=MsoPlainText style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: normal"><SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: Courier; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'MS Mincho'"><SPAN
style="mso-spacerun: yes"> </SPAN>**WARNING**********************************************************************<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: normal"><SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: Courier; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'MS Mincho'"><SPAN
style="mso-spacerun: yes">
</SPAN>An EQUIP-CTRL sequence will be overridden because<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: normal"><SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: Courier; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'MS Mincho'"><SPAN
style="mso-spacerun: yes">
</SPAN>the selected equipment cannot meet the resulting<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: normal"><SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: Courier; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'MS Mincho'"><SPAN
style="mso-spacerun: yes">
</SPAN>flow requirements.<o:p></o:p></SPAN></P><SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: Courier; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'MS Mincho'; mso-bidi-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><SPAN
style="mso-spacerun: yes">
</SPAN>Loop: prim chw loop<SPAN
style="mso-spacerun: yes">
</SPAN>First occurrence:<SPAN style="mso-spacerun: yes"> </SPAN>6/21/
4</SPAN>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT size=2><FONT size=3>and
the chillers</FONT> </FONT><FONT size=3>always run in parallel. My
question comes because I have been adjusting the capacity of the two
RTUs with the chilled water coils and if the cooling capacity of those units
is well below the capacity of the chillers then they stage properly or if I
increase the capacity of the chillers well beyond the capacity of the RTUs
then they stage properly, but when the capacity of the RTU's is close to
the capacity of the chillers then I get that error above and the chillers
don't stage. </FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT size=2></FONT> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt">Any help would be greatly
appreciated.</P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT size=2></FONT> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt">Joe Hager</P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt">DMI</P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt">(617) 527-1525 </P></DIV><PRE>
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