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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>I typically use RMI’s EMIT tool for these calcs. </span><a href="http://www.rmi.org/rmi/ModelingTools">http://www.rmi.org/rmi/ModelingTools</a><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> equest-users-bounces@lists.onebuilding.org [mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Nick Caton<br><b>Sent:</b> July-06-11 4:20 PM<br><b>To:</b> James Hansen; equest-users@lists.onebuilding.org<br><b>Subject:</b> Re: [Equest-users] my math on DWH efficiency?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Hmm… I read this quickly and it seemed off so I double checked:<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span lang=EN-US style='font-size:10.0pt;font-family:"Times New Roman","serif"'>TANK-UA<o:p></o:p></span></b></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US style='font-size:12.0pt;font-family:"Times New Roman","serif"'>The overall heat loss coefficient (UA) of the heater. The heat loss is calculated as this value times the temperature difference between the water in the heater and the environmental temperature. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>You got the 90.1 calc right: SL = 20 + 35*sqrt(240) = 562 <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Rephrasing the DOE2 help entry copied above: SL = UA * delta-T<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Set: 562 = UA * 70<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Then: UA = 562/70 = 8.03<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>As I understand it, TANK-UA rolls together the properties of both the insulation and surface area, so given TANK-UA you shouldn’t need to work in the tank volume or area to find the standby loss for a given delta-T. That’s my take – hope it helps =)!<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>~Nick<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><img border=0 width=119 height=37 id="Picture_x0020_1" src="cid:image001.jpg@01CC3BF9.E95E5230" alt="cid:489575314@22072009-0ABB"></span><b><span lang=EN-US style='font-family:"Stylus BT","sans-serif";color:#2D4D5E'><o:p></o:p></span></b></p><p class=MsoNormal><b><span lang=EN-US style='font-family:"Stylus BT","sans-serif";color:#2D4D5E'><o:p> </o:p></span></b></p><p class=MsoNormal><b><span lang=EN-US style='font-size:12.0pt;font-family:"Stylus BT","sans-serif";color:#2D4D5E'>NICK CATON, P.E.<o:p></o:p></span></b></p><p class=MsoNormal><span lang=EN-US style='font-size:7.5pt;color:#CC9900'>SENIOR ENGINEER<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:7.5pt;color:#CC9900'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;color:#2D4D5E'>Smith & Boucher Engineers</span><span lang=EN-US style='font-size:7.5pt;font-family:"Times New Roman","serif";color:#CC9900'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;color:#2D4D5E'>25501 west valley parkway, suite 200<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;color:#2D4D5E'>olathe, ks 66061<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;color:#2D4D5E'>direct 913.344.0036<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;color:#2D4D5E'>fax 913.345.0617<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><a href="www.smithboucher.com" title="blocked::www.smithboucher.com"><span style='font-size:10.0pt'>www.smithboucher.com</span></a></span><u><span lang=EN-US style='font-size:10.0pt;color:blue'> </span></u><span lang=EN-US style='color:#1F497D'><o:p></o:p></span></p></div><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> equest-users-bounces@lists.onebuilding.org [mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>James Hansen<br><b>Sent:</b> Wednesday, July 06, 2011 10:31 AM<br><b>To:</b> equest-users@lists.onebuilding.org<br><b>Subject:</b> [Equest-users] my math on DWH efficiency?<o:p></o:p></span></p></div></div><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>I had a question about calculating baseline 90.1 efficiency for electric DWHs (tank type).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Based on Table 7.8, my efficiency needs to be SL = 20 + 35*sqrt(V) at a 70 degree delta T between water and ambient, where SL is the standby loss in btuh, and V is the volume of the tank.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>If, in my proposed model, I have a 240 gallon tank (meaning my baseline has the same volume), it would appear that the maximum standby loss at a 70 degree delta should be 562 btuh [20 + 35 * sqrt(240)]<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Since eQuest calculates the heat loss by multiplying the UA (thermal conductivity of storage tank) by the tank, it would appear that my UA for this particular example would be 562 / (70*240), or 0.0334.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>That way, at a 70 degree delta, the heat loss (SL) would be 0.0334 Btu/hr-gal-F * 240 gallons * 70 F = 562 btuh<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Does that sound about right? <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Thanks to anyone that has a quick chance to review!<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><b><span lang=EN-US style='font-family:"Arial","sans-serif";color:teal'>GHT Limited<br></span></b><b><span lang=EN-US style='font-family:"Arial","sans-serif"'><ns0:PersonName><span style='color:black'>James Hansen</span></ns0:PersonName></span></b><b><span lang=EN-US style='color:black'>, PE, LEED AP<o:p></o:p></span></b></p><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Senior Associate</span></b><b><span lang=EN-US style='color:black'><o:p></o:p></span></b></p><p class=MsoNormal><span lang=EN-US style='font-size:7.5pt;font-family:"Arial","sans-serif"'><ns0:Street><ns0:address><span style='color:black'>1010 N. 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