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<p class="MsoNormal"><span style="color:#1F497D">Nick,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">It has always been my understanding that combustion efficiency includes flue losses as it is calculated based on CO2% or O2% in the stack gas and net stack temperature (stack temp.-boiler room ambient temp entering
the burner). The only other thing I can think of that would affect the thermal efficiency or useful Btu’s output as steam or hot water/fuel Btu’s input would be radiant and convective jacket losses from the boiler shell at 100% firing rate. Although manufacturers
are reluctant to publish data on jacket losses, they could typically range from about 1%-4% based on the design and mfg. This will be a fixed quantity of Btu’s no matter what the firing rate is, so this loss as a % of boiler load increases as % load decreases.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">As an example, look at an Ajax or Rite Boiler. They look pretty similar and are both manufactured within a fairly close proximity of each other. The
<u>front</u> and <u>back </u>ends have uninsulated steel head plates about 1” thick to gain access to the tube bundle. Below the head plates are uninsulated thin sheet metal panels to gain access to the burners. With the boilers firing, I’ve measured temperatures
of the upper plates in the 200-300 deg. range and the lower sheet metal panels in the area of 450 deg. This is kind of an extreme scenario, but the jacket losses are probably a significant number even though the rated or measured combustion efficiency might
be 82%.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">The other piece of the puzzle when it comes to seasonal boiler efficiency I don’t know how DOE-2 handles would be cycling losses. If you take that Rite or Ajax boiler equipped with an atmospheric burner, the
seasonal efficiency could easily approach 50%. During every off cycle, boiler room air will flow up through the boiler cooling the firebrick and mass of the boiler. The next firing cycling, those draft cooling losses need to be replaced by additional Btu’s.
A cycling boiler with a power burner could also have a low seasonal efficiency as the result of cooling losses from pre-purge and post-purge operation to get rid of unburned fuel.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I don’t know if that helps or confuses the matter. After that long dissertation, I would suggest using the rated combustion efficiency.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">My best,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Mike Busman<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Michael R. Busman, CEM</span></b><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Lead Project Engineer II</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Chevron Energy Solutions</span></b><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">A Division of Chevron U.S.A., Inc.</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">145 S. State College Blvd.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Brea, CA 92821
</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Direct 714-671-3561</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Fax 714-671-3438</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">eFax 866-420-0335 (Include my Full Name followed by "CAI:MHTZ" on Cover Sheet)</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D">Mobile 310-387-2083</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1F497D"><a href="mailto:mbusman@chevron.com">mbusman@chevron.com</a></span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<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""> equest-users-bounces@lists.onebuilding.org [mailto:equest-users-bounces@lists.onebuilding.org]
<b>On Behalf Of </b>Nick Caton<br>
<b>Sent:</b> Friday, April 26, 2013 10:55 AM<br>
<b>To:</b> equest-users@lists.onebuilding.org<br>
<b>Subject:</b> [Equest-users] Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi everyone!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">90.1-2007 Table 6.8.1F for boilers prescribes a minimum <u>combustion</u> efficiency (E<span style="font-size:7.0pt">C</span>) of 82% for gas boilers larger than 2.5MBtu/h. This is the burner’s efficiency before flue losses.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The same boiler’s <u>thermal</u> efficiency, inclusive of flue losses, would be a lesser figure.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When modeling such boilers for an Appendix G baseline, what is actually appropriate to enter for the boiler’s HIR input? As I understand it, this HIR input in eQuest is the inverse of thermal efficiency (net input vs. net output), and
would be inclusive of flue losses.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">This is for a LEED project, so I’d like to cite something solid to demonstrate what thermal efficiency is appropriate to assume for a baseline boiler of this size. Has anyone gone down this path before?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">~Nick<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"><img border="0" width="119" height="37" id="Picture_x0020_1" src="cid:image001.jpg@01CE4270.7E2CF910" alt="cid:489575314@22072009-0ABB"></span><b><span style="font-family:"Stylus BT","sans-serif";color:#2D4D5E"><o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-family:"Stylus BT","sans-serif";color:#2D4D5E"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span 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 style="font-size:7.5pt;color:#CC9900">SENIOR ENGINEER<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;color:#CC9900"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#2D4D5E">Smith & Boucher Engineers</span><span style="font-size:7.5pt;font-family:"Times New Roman","serif";color:#CC9900"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#2D4D5E">25501 west valley parkway, suite 200<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#2D4D5E">olathe, ks 66061<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#2D4D5E">direct 913.344.0036<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#2D4D5E">fax 913.345.0617<o:p></o:p></span></p>
<p class="MsoNormal"><span 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 style="font-size:10.0pt;color:blue">
</span></u><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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