<div dir="ltr"><div><span style="font-size:13px">Michael,</span></div><div><span style="font-size:13px"><br></span></div><div><span style="font-size:13px">One other item to consider once you solve your flow capacity issues is the system head aspect. eQuest doesn't apply the head input at the pump to the system, but rather the system head at design conditions is set to the sum of the largest chiller evaporator head, pipe head, and the largest coil head. The defaults (at design conditions) for a centrifugal chiller and a cooling coil are 20 ft. and 15 ft. respectively, which are more or less universally good assumptions if you don't have any other data. However, the piping head can vary greatly project to project, and most people don't bother to change the default of 21.6 ft. So, in your case, the total head at a design flow of 4650 gpm is 20 + 15 + 21.6 = 56.6 ft. Since your pumps are rated for 200 ft head, I would guess that 56 ft. is way too low. A good practice is to enter a User Expression for the loop Pipe Head field like the following:</span></div><div><span style="font-size:13px"><br></span></div><div>0.9*200 - 20 - 15</div><div><br></div><div>Where the 200 is the head you entered for the pump, 20 is the head loss across the chiller, and 15 is the head loss across one coil. This will set the total system head to 90% of the rated pump head at design conditions (accounts for the safety factor that engineers apply to pump selections). If you keep the piping head as default, your savings will be greatly exaggerated once you fix your flow capacity issues. You can check the design values for loop flow and head in the PV-A report.</div><div><br></div><div>Aaron</div><span style="font-size:13px"><div><span style="font-size:13px"><br></span></div>---------- Forwarded message ----------</span><br style="font-size:13px"><span style="font-size:13px">From: Julien Marrec <<a href="mailto:julien.marrec@gmail.com">julien.marrec@gmail.com</a>></span><br style="font-size:13px"><span style="font-size:13px">To: Joe Fleming <<a href="mailto:joe@thespinnakergroupinc.com">joe@thespinnakergroupinc.com</a>></span><br style="font-size:13px"><span style="font-size:13px">Cc: "<a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a>" <<a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a>></span><br style="font-size:13px"><span style="font-size:13px">Date: Fri, 19 Jun 2015 10:22:28 +0200</span><br style="font-size:13px"><span style="font-size:13px">Subject: Re: [Equest-users] VFD Pumping</span><br style="font-size:13px"><div dir="ltr" style="font-size:13px"><div><div><div><div><div><div>All,<br><br></div>I looked briefly at Mike's input file.<br><br></div><b>Paul,</b><br><br></div>It's two-way, so that's ok. For those who may be wondering why you need two-way valves, that is in order to have a pressure change (as they close) going back to the VFD for modulation. That's true in real life too.<br><br></div><b>Joe,</b><br><br></div>Bingo on your 1) point. (see extract of warnings below).<br><br><div><b>Mike,</b><br><br></div><div>I suggest you also investigate your tons of warning about insufficient heating capability, because you do have 1851 hours below heating throttling range...<br></div><div><br></div>-------------------------------------------------------------------------------------------<br><br><br></div>Here are an extract of the warnings<br><br> **WARNING**********************************************************************<br> Pump: Chlr1 (ElCentHerm) Pump has a total user-specified flow<br> of 1300. gpm, but the loop flow is 2325. gpm.<br><br> **WARNING**********************************************************************<br> Pump: Chlr2 (ElCentHerm) Pump has a total user-specified flow<br> of 1300. gpm, but the loop flow is 2325. gpm.<br><br> **WARNING**********************************************************************<br> Pump: CW Loop Pump has a total user-specified flow<br> of 1500. gpm, but the loop flow is 5649. gpm.<br><br> **WARNING**********************************************************************<br> Pump: CW Loop Pump cannot match the system<br> flow at the minimum required head.<br> Required system flow = 2824.3 gpm at head = 47.2<br> Pump balance point = 2665.2 gpm at head of 43.5<br> If the pump was sized by default, most likely this<br> is caused by a primary equipment unit operating at<br> greater than its design flow, and causing a pressure<br> drop greater than design. Try increasing the pump<br> head or head ratio to compensate.<br> First occurrence is on 1/ 1, hour 9<br><br> **WARNING**********************************************************************<br> Pump: Chlr1 (ElCentHerm) Pump cannot match the system<br> flow at the minimum required head.<br> Required system flow = 2325.4 gpm at head = 42.6<br> Pump balance point = 2314.3 gpm at head of 42.3<br> If the pump was sized by default, most likely this<br> is caused by a primary equipment unit operating at<br> greater than its design flow, and causing a pressure<br> drop greater than design. Try increasing the pump<br> head or head ratio to compensate.<br> First occurrence is on 4/27, hour 15<br><br> **WARNING**********************************************************************<br> Pump: Chlr2 (ElCentHerm) Pump cannot match the system<br> flow at the minimum required head.<br> Required system flow = 2325.4 gpm at head = 48.6<br> Pump balance point = 2289.5 gpm at head of 47.3<br> If the pump was sized by default, most likely this<br> is caused by a primary equipment unit operating at<br> greater than its design flow, and causing a pressure<br> drop greater than design. Try increasing the pump<br> head or head ratio to compensate.<br> First occurrence is on 4/29, hour 10<br></div><div class="gmail_extra" style="font-size:13px"><br clear="all"><div><div dir="ltr">--<br>Julien Marrec, EBCP, BPI MFBA<br>Energy&Sustainability Engineer<br>T: <a href="tel:%2B33%206%2095%2014%2042%2013" value="+33695144213" target="_blank">+33 6 95 14 42 13</a><br><span style="color:rgb(0,0,0)"><br></span><span style="color:rgb(0,0,0)">LinkedIn (en) : <a href="http://www.linkedin.com/in/julienmarrec" target="_blank">www.linkedin.com/in/julienmarrec</a><br>LinkedIn (fr) : <a href="http://www.linkedin.com/in/julienmarrec/fr" target="_blank">www.linkedin.com/in/julienmarrec/fr</a></span><br><span style="color:rgb(0,0,0)"><a href="http://www.linkedin.com/in/julienmarrec" target="_blank"></a></span></div></div><br><div class="gmail_quote">2015-06-18 21:28 GMT+02:00 Joe Fleming <span dir="ltr"><<a href="mailto:joe@thespinnakergroupinc.com" target="_blank">joe@thespinnakergroupinc.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Hi Michael,<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">To add to what Paul mentioned about 2-way valves;<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">What are your building loads looking like in the eQuest output reports? There are 2 potential scenarios that may lead to limited savings from a properly modeled VFD installation;<u></u><u></u></span></p><p><u></u><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">1.<span style="font-size:7pt;font-family:'Times New Roman'"> </span></span><u></u><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">If the pump is under sized for the loads input<u></u><u></u></span></p><p><u></u><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">2.<span style="font-size:7pt;font-family:'Times New Roman'"> </span></span><u></u><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">If the loads are constant and mostly internal<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Kind Regards<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p><div><p class="MsoNormal"><b><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray"><u></u> <u></u></span></b></p><p class="MsoNormal"><b><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray">Joe Fleming </span></b><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray">|<b> PE, </b>LEED AP BD+C, BEMP</span><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></p><p class="MsoNormal"><i><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray">Commissioning Agent & Energy Consultant </span></i><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray">| </span><b><span style="font-size:11pt;font-family:Arial,sans-serif;color:rgb(164,177,45)">The Spinnaker Group</span></b><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></p><p class="MsoNormal"><b><span style="font-size:11pt;font-family:Arial,sans-serif;color:rgb(127,127,127)"><a href="mailto:joe@thespinnakergroupinc.com" target="_blank"><span style="color:rgb(127,127,127)">joe@thespinnakergroupinc.com</span></a></span></b><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></p><p class="MsoNormal"><b><i><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray">Cell</span></i></b><span style="font-size:11pt;font-family:Arial,sans-serif;color:gray"> <a href="tel:561-602-3132" value="+15616023132" target="_blank">561-602-3132</a> | <b><i>Office</i></b> <a href="tel:754-800-3100" value="+17548003100" target="_blank">754-800-3100</a></span><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></p></div><p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p><div><div style="border-style:solid none none;border-top-color:rgb(181,196,223);border-top-width:1pt;padding:3pt 0in 0in"><p class="MsoNormal"><b><span style="font-size:10pt;font-family:Tahoma,sans-serif">From:</span></b><span style="font-size:10pt;font-family:Tahoma,sans-serif"> Equest-users [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Mike Schaefer<br><b>Sent:</b> Thursday, June 18, 2015 2:49 PM<br><b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br><b>Subject:</b> [Equest-users] VFD Pumping<u></u><u></u></span></p></div></div><div><p class="MsoNormal"><u></u> <u></u></p><div><p class="MsoNormal">I’ve performing an energy model to compare VFD Chiller pumping and Constant Volume Chiller pumping for a multi-story office building using eQUEST v 3.65. Although I expect to save pump energy utilizing VFD pumping I’m not seeing a savings and I believe this is due to my “Pump Properties Inputs”.<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">For both the VFD and constant volume pump scenarios I’ve input the scheduled pump flow (1,300 gpm) and head (200 ft) and the other pump inputs are default values. The energy difference between the two pumping scenarios is negligible, however, if I set the pump gpm to a default, which inputs a 1.00 Flow Ratio, the energy savings is significant in the VFD pumping model.<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Am I over defining the pumps by inputting the scheduled pump gpm? Should the pump gpm always be set to default?<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Thanks,<u></u><u></u></p><p class="MsoNormal"><span style="font-family:Calibri,sans-serif"><br><br></span><strong><span style="font-family:Arial,sans-serif">Michael</span></strong></p></div></div></div></blockquote></div></div>
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