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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>A question for the group that’s stumping me right now.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’m modeling a building served by a campus chiller
plant. The chiller plant is only available during summer months, with a
7-5 weekdays-only schedule and snap operation limiting the plant to 70degF OAT
and above. This building will require cooling at times when the plant is
unavailable, so the design team is considering using a cooling tower as a “water
economizer chiller”. I’m familiar with the equest workaround
for water economizers, and have used it before. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The difficulty is in setting up a control scheme that allows
the primary chilled water loop to operate in any condition that requires
cooling AND allows the two chilled water sources to operate as intended.
To summarize the sequence requirements:<o:p></o:p></span></font></p>
<ul style='margin-top:0in' type=disc>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>The chilled water meter
(representing the campus plant)<o:p></o:p></span></font></li>
<ul style='margin-top:0in' type=circle>
<li class=MsoNormal style='mso-list:l0 level2 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Is the only chilled water
source when both of these conditions are met -<o:p></o:p></span></font></li>
<ul style='margin-top:0in' type=square>
<li class=MsoNormal style='mso-list:l0 level3 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>During scheduled operation<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level3 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>When the OAT is above snap
temperature<o:p></o:p></span></font></li>
</ul>
</ul>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>The water economizer cooling
tower<o:p></o:p></span></font></li>
<ul style='margin-top:0in' type=circle>
<li class=MsoNormal style='mso-list:l0 level2 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Operates when there is cooling
demand outside of summer months<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level2 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Operates during scheduled
operation of the campus plant when OAT is below the chiller plant snap
temperature AND there is cooling demand<o:p></o:p></span></font></li>
</ul>
</ul>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’ve tried playing around with equipment control and
load management, and can’t seem to get a sequence that works. I’m
about ready to simply let the chilled water run without schedule restrictions
and figure out what the plant vs cooling tower operation hours are through
hourly report post-processing.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Anyone have any suggestions?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Steven<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Bookman Old Style"><span
style='font-size:12.0pt;font-family:"Bookman Old Style"'>Steven Savich, LEED AP</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face="Bookman Old Style"><span
style='font-size:10.0pt;font-family:"Bookman Old Style"'>Systems West Engineers</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:Street w:st="on"><st1:address w:st="on"><font size=2
face="Bookman Old Style"><span style='font-size:10.0pt;font-family:"Bookman Old Style"'>411
High Street</span></font></st1:address></st1:Street><o:p></o:p></p>
<p class=MsoNormal><st1:place w:st="on"><st1:City w:st="on"><font size=2
face="Bookman Old Style"><span style='font-size:10.0pt;font-family:"Bookman Old Style"'>Eugene</span></font></st1:City><font
size=2 face="Bookman Old Style"><span style='font-size:10.0pt;font-family:
"Bookman Old Style"'>, <st1:State w:st="on">OR</st1:State> <st1:PostalCode
w:st="on">97401-2427</st1:PostalCode></span></font></st1:place><o:p></o:p></p>
<p class=MsoNormal><font size=2 face="Bookman Old Style"><span
style='font-size:10.0pt;font-family:"Bookman Old Style"'>(541) 342-7210</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face="Bookman Old Style"><span
style='font-size:10.0pt;font-family:"Bookman Old Style"'>(541) 342-7220 (fax)</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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