<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:10pt"><div>Jim:<br><br>To avoid confusion, I look up the default curves and use the same type of curve.<br><br>For example, the EIR f(CHWT & ECT) default curve is a bi-quadratic in T curve as you indicated below. <br><br>For the PLR curves, the default is a bi-quadratic in ratio and DT. eQuest defines this curve as an EIR f(PLR & DT). Someone sent a cut & paste from the DOE manual which stated this should be a quadratic curve, which I do not agree with. Was that a DOE typo or can someone else explain why?<br><br>So normalize the PLR to AHRI standards. The DT is the difference between the chilled water leaving temperature and the condenser water entering temperature.<br></div><div style="font-family: times new roman,new york,times,serif; font-size: 10pt;"><br>Paul
Diglio<br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> James Hansen <JHANSEN@ghtltd.com><br><b><span style="font-weight: bold;">To:</span></b> Paul Diglio <paul.diglio@sbcglobal.net>; equest-users@lists.onebuilding.org<br><b><span style="font-weight: bold;">Sent:</span></b> Mon, March 14, 2011 11:34:22 AM<br><b><span style="font-weight: bold;">Subject:</span></b> RE: [Equest-users] which chiller curve(s) to modify?<br></font><br>
<style><!--
_filtered {font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
_filtered {font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
_filtered {font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"sans-serif";}
a:link, span.MsoHyperlink
{
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{
color:purple;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"sans-serif";}
span.emailstyle17
{
font-family:"sans-serif";
color:windowtext;}
span.EmailStyle19
{
font-family:"sans-serif";
color:#1F497D;}
.MsoChpDefault
{
font-size:10.0pt;}
_filtered {
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{}
--></style><div class="WordSection1"><p class="MsoNormal"><span style="font-family: "sans-serif"; color: rgb(31, 73, 125);">Sorry, meant that my condenser water entering temperature to the chiller follows the AHRI guidelines for condenser water reset (83 degrees at full load, going down to 65 degrees at 50% in a linear fashion, and then staying at 65 degrees down to 10%).</span></p><div><p class="MsoNormal"><b><span style="font-family: "sans-serif"; color: rgb(49, 132, 155);"> </span></b></p></div><p class="MsoNormal"><span style="font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><div><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;"><p class="MsoNormal"><b><span style="font-size: 10pt; font-family: "sans-serif";">From:</span></b><span style="font-size: 10pt;
font-family: "sans-serif";"> Paul Diglio [mailto:paul.diglio@sbcglobal.net] <br><b>Sent:</b> Monday, March 14, 2011 11:32 AM<br><b>To:</b> James Hansen; equest-users@lists.onebuilding.org<br><b>Subject:</b> Re: [Equest-users] which chiller curve(s) to modify?</span></p></div></div><p class="MsoNormal"> </p><div><div><p class="MsoNormal"><span style="font-size: 10pt;">Jim:<br><br>What do you mean by condenser relief?<br><br>Paul Diglio</span></p></div><div><p class="MsoNormal"><span style="font-size: 10pt;"> </span></p><div><div class="MsoNormal" style="text-align: center;" align="center"><span style="font-size: 10pt; font-family: "sans-serif";"><hr align="center" width="100%" size="1"></span></div><p class="MsoNormal" style="margin-bottom: 12pt;"><b><span style="font-size: 10pt; font-family: "sans-serif";">From:</span></b><span style="font-size: 10pt; font-family: "sans-serif";"> James Hansen
<JHANSEN@ghtltd.com><br><b>To:</b> equest-users@lists.onebuilding.org<br><b>Sent:</b> Mon, March 14, 2011 11:23:04 AM<br><b>Subject:</b> [Equest-users] which chiller curve(s) to modify?</span><span style="font-size: 12pt; font-family: "serif";"></span></p><div><p class="MsoNormal">I know there was a recent discussion about chiller curves, but I can’t seem to access <a rel="nofollow" target="_blank" href="http://www.gard.com">www.gard.com</a> right now, so I thought would send out this email since I don’t remember it being discussed.</p><p class="MsoNormal"> </p><p class="MsoNormal">I have two different curves for a standard water-cooled 200-ton screw chiller:</p><p class="MsoNormal"> </p><p class="MsoListParagraph">1)<span style="font-size: 7pt; font-family: "serif";"> </span>EIR based on PLR, but with AHRI condenser relief</p><p class="MsoListParagraph">2)<span style="font-size: 7pt;
font-family: "serif";"> </span>EIR based on PLR, with NO condenser relief, and varying return chilled water temperature (from design at 100% to only about a 2 degree delta between supply and return at the 20% load range)</p><p class="MsoNormal"> </p><p class="MsoNormal">Which curves should I modify with custom curves? I am so confused.</p><p class="MsoNormal"> </p><p class="MsoNormal">The f(PLR) curve says it should be the EIR vs PLR with no condenser water reset. That one’s the easy one. I already set that one up, and it’s about $1000 cheaper a year than the default curve, so I know it’s at least in the right range.</p><p class="MsoNormal"> </p><p class="MsoNormal">But the f(t evap leaving, t cond entering) says it’s a quadratic curve, but since there are two variables, shouldn’t it be bi-quadratic like the Cooling Capacity curve as a function of entering CW and leaving
CHW?</p><p class="MsoNormal"> </p><p class="MsoNormal">When you all get chiller PLR curves with condenser relief, which curve(s) do you modify and to what extent?</p><p class="MsoNormal"> </p><p class="MsoNormal">Thanks!</p><p class="MsoNormal"> </p><p class="MsoNormal"><b><span style="color: teal;">GHT Limited<br></span><span style="color: black;">James Hansen, PE, LEED AP</span></b></p><p class="MsoNormal"><b><span style="font-size: 10pt; color: black;">Senior Associate</span></b></p><p class="MsoNormal"><span style="font-size: 7.5pt; color: black;">1010 N. Glebe Rd, Suite 200</span></p><p class="MsoNormal"><span style="font-size: 7.5pt; color: black;">Arlington, VA 22201-4749</span></p><p class="MsoNormal"><span style="font-size: 7.5pt; color: black;">703-338-5754 (Cell)</span></p><p class="MsoNormal"><span style="font-size: 7.5pt; color: black;">703-243-1200 (Office)</span></p><p class="MsoNormal"><span style="font-size: 7.5pt;
color: black;">703-276-1376 (Fax)</span></p><p class="MsoNormal"><span style="color: teal;"><a rel="nofollow" target="_blank" href="http://www.ghtltd.com/"><span style="font-size: 10pt;">www.ghtltd.com</span></a></span></p><p class="MsoNormal"><b><span style="color: rgb(49, 132, 155);"> </span></b></p><p class="MsoNormal"> </p></div></div></div></div></div></div></div>
</div></body></html>