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--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="color:#1f497d">Hi All,</span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal">
<span style="color:#1f497d">I ran a quick test by creating a simple model with a condensing boiler. I set the efficiency to 92% at 80°F return temp. Then I used the default eQUEST condensing boiler curve to manually calculate the boiler’s efficiency at 140F:</span></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal" style="text-indent:.5in"><span style="color:#1f497d">92% (rated eff) / 1.079 (curve output at 140°F and 100% PLR, see line 13 in Bill’s screenshot of the curve below) = 85%</span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d">I then entered this efficiency as a parametric run, also changing the RATED-HWR-T keyword to 140 F. Theoretically, this should have no effect on gas usage, since we’re defining the same exact boiler in both cases.</span></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d">The results: the annual heating usage changed by 10 Therms (out of ~8,000 total). This difference is a fraction of one percent and can be attributed to rounding error.</span></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d">My conclusion is that it’s OK to enter the efficiency of condensing boilers at any return temperature as long as you coordinate this with the curve you’re using and the RATED-HWR-T keyword.</span></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d">Mike Karpman</span></p><p class="MsoNormal"><b><span style="color:#006600">Karpman Consulting</span></b></p><p class="MsoNormal">
<span style="color:#1f497d">(860) 430-9110</span></p><p class="MsoNormal"><span style="color:#1f497d">41C New London Turnpike</span></p><p class="MsoNormal"><span style="color:#1f497d">Glastonbury, CT 06033</span></p><p class="MsoNormal">
<span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Bishop, Bill<br>
<b>Sent:</b> Wednesday, September 11, 2013 5:17 PM<br><b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a><br><b>Subject:</b> [Equest-users] eQUEST condensing boilers RATED-HWR-T</span></p>
</div></div><p class="MsoNormal"> </p><p class="MsoNormal"><span style="color:#1f497d">Has anyone tried verifying that the RATED-HWR-T keyword modifies the hourly boiler HIR appropriately?</span></p><p class="MsoNormal"> </p>
<p class="MsoNormal"><img width="538" height="251" id="Picture_x0020_2" src="cid:image001.jpg@01CEAFA9.CCC8D250" alt="cid:image005.jpg@01CEAF0F.767C2220"></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal">
<span style="color:#1f497d">The default eQUEST condensing boiler curve is normalized at 80°F and 100% fire (1.0 PLR):</span></p><p class="MsoNormal"> </p><p class="MsoNormal"><img width="537" height="329" id="Picture_x0020_1" src="cid:image002.jpg@01CEAFA9.CCC8D250"></p>
<p class="MsoNormal"> </p><p class="MsoNormal"><span style="color:#1f497d">The DOE-2 documentation says that RATED-HWR-T is the temperature at which the efficiency and capacity is defined. So I guess eQUEST takes this into account when applying the performance curve.</span></p>
<p class="MsoNormal"><span style="color:#1f497d">Has anyone tried to verify this by entering the appropriate combinations of capacity, HIR and HWR-T for two or more runs and comparing the results?</span></p><p class="MsoNormal">
<span style="color:#1f497d">As Obama said, “to paraphrase Ronald Reagan, we don’t just <i>trust</i> but also <i>verify</i>”.</span></p><p class="MsoNormal"> </p><p class="MsoNormal"><span style="color:#1f497d">Thanks,</span></p>
<p class="MsoNormal"><span style="color:#1f497d">Bill</span></p><p class="MsoNormal"> </p><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium","sans-serif";color:black">William Bishop, PE, BEMP, BEAP, LEED AP </span></b><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium","sans-serif";color:#006600">|</span></b><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium","sans-serif";color:black"> Pathfinder Engineers & Architects LLP</span></b></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial","sans-serif";color:black">Senior Energy Engineer</span></p><p class="MsoNormal"><span style="font-size:5.0pt;font-family:"Arial","sans-serif";color:black"> </span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial","sans-serif"">134 South Fitzhugh Street</span><span style="font-size:9.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:9.0pt;font-family:"Arial","sans-serif"">Rochester, NY 14608</span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial","sans-serif"">T: (585) 325-6004 <span style="color:black">Ext. 114</span></span><span style="font-size:12.0pt;font-family:"Times New Roman","serif""> </span><span style="font-size:9.0pt;font-family:"Arial","sans-serif"">F: (585) 325-6005<span style="color:black"></span></span></p>
<p class="MsoNormal"><a href="mailto:wbishop@pathfinder-ea.com"><span style="font-size:9.0pt;font-family:"Arial","sans-serif"">bbishop@pathfinder-ea.com</span></a><span style="font-size:9.0pt;font-family:"Arial","sans-serif";color:black"> </span><a href="http://www.pathfinder-ea.com/"><span style="font-size:9.0pt;font-family:"Arial","sans-serif"">www.pathfinder-ea.com</span></a><span style="font-size:9.0pt;font-family:"Arial","sans-serif";color:black"></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:Webdings;color:green">P</span><span style="font-size:14.0pt;font-family:"Times New Roman","serif";color:green"> </span><span style="font-size:7.5pt;font-family:"Times New Roman","serif";color:green">Sustainability – the forest AND the trees.</span><span style="font-size:18.0pt;font-family:Webdings;color:green"> </span><span style="font-size:14.0pt;font-family:Webdings;color:green">P</span><span style="font-size:14.0pt;color:green"> </span></p>
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