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<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**********************************************************************<?xml:namespace
prefix = o ns = "urn:schemas-microsoft-com:office:office"
/><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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