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<p class="MsoNormal"><span style="color:#1F497D">I would like to issue a correction to my previous email.<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 AHRI I-B-R ratings publication does include boilers with inputs > 2500 MBH. I’ve seen several entries in the April 2009 publication where the 2500 MBH input is exceeded, and values are listed for both combustion
and thermal efficiency, an example of which is shown below. I’m not sure why then ASHRAE 90.1 doesn’t specify Et for the larger hot water boilers.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><img width="389" height="370" id="_x0000_i1034" src="cid:image007.png@01CE514E.EACC2770"><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thus, I go back to the point I previously made where I think we should model the thermal efficiency values, and they are available via AHRI.<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">In addition, there was another point made about additional losses and I agree. While not spelled out in Appendix G, the losses associated with boiler cycling can be significant and therefore should be modeled.
These are the pre-purge and post-purge losses previously referenced by Mike in this thread. My understanding is that if you combine the flue losses, jacket losses, and cycling losses, you get the overall fuel-to-steam efficiency. If the boiler(s) are significantly
oversized, the boilers will cycle a lot and fuel-to-steam efficiency can be quite a bit lower than either the combustion or thermal efficiency numbers. If this is not taken into account by energy modelers, then during the M&V phase, a big descrepancy will
show up between modeled boiler efficiency and actual boiler efficiency. The M&V engineers will catch this. Ramya Shivkumar brought this up in separate email to me regarding M&V and I completely agree.<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">Several years ago, I performed detailed data collection and analysis on a pair of steam boilers for a hospital, as part of an energy audit/study. The boilers were oversized and cycling a lot, but even more so
because the operator ran both even though he needed only one because he wanted both boilers hot and ready to go in case one went down. If you’ve ever been in his shoes, with the potential to lose your job if the doctors didn’t have what they needed to run
the hospital, you will understand why the operator was running the boilers the way he did. I simply pointed out through measurements that the boilers were cycling a lot because they only had a 4:1 turndown burner (i.e. cycles when load < 25%). The overall
effect was that the boilers were operating at an overall fuel-to-steam efficiency of ~ 70 to 72 % versus the rated Ec value of 80 to 82 %. I was just showing how much they could save if they only ran one boiler. For what it’s worth, the operator did not
take my suggestion, but this does show that the difference between the combustion and fuel-to-steam efficiency can be significant. Thus minimum turndown and cycling should be taken into account in the energy models. eQuest does this via startup and standby
times.<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">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="color:#339966">JAH<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><i><span style="color:#339966">James A. Hess, PE, CEM, BEMP</span></i></b><span style="color:#1F497D"><br>
Energy Engineer<br>
TME, Inc.<br>
Little Rock, AR<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Mobile: (501) 351-4667<o:p></o:p></span></p>
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<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>James Hess<br>
<b>Sent:</b> Monday, May 13, 2013 5:39 PM<br>
<b>To:</b> Nick Caton; equest-users@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Equest-users] Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Excellent post Nick! </span><span style="font-family:Wingdings;color:#1F497D">J</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">Seems like every time I read some part of ASHRAE 90.1 in detail, I come away with learning something new.<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">Table 6.8.1.F does specify Et for the larger (> 2500 MBH)
<u>steam boilers after 3/2/2010</u> (see screen shot below)<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 wonder then if the values for the larger capacity hot water boilers is either a misprint, or since this size boiler is not under the AHRI I-B-R testing document, the 90.1 committee didn’t know what to put so
they left it as Ec (i.e. seems like there’s a hole here).<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">This is a bit confusing, but my overall take away is that Et is specified enough times in the table that the intent is to account for both the flue losses and the other major losses included in the Et values
(i.e. skin/jacket/convection heat losses). Therefore, I think we should be using Et values whenever possible.<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">For smaller capacity hot water boilers, those values are available from AHRI. For larger, well, we don’t run into a lot of those so this may not be a big deal (i.e. usually, you put in more smaller boilers versus
fewer larger boilers, because your “N+1” redundant capacity costs much less). For the steam boilers, I believe we just have to get that data from the manufacturer, as available. For example, this info is available from Cleaver Brooks and Hurst. I’ve seen
it.<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">Regarding the last item of your post, I’ve usually just used the default natural draft boiler and its associated curve in eQuest. I would then compare to the better condensing curve for the Proposed Design,
since just about all of our projects utilize the high efficiency condensing hot water boiler type. The natural draft curve is not that good, but I interpret section G.3.1.3.2 literally, and therefore use the natural draft boiler curve. I would agree that
what you are doing is more realistic because I don’t think many manufacturers make or projects utilize the natural draft boilers anymore. The more demanding emissions and combustion controls associated with modern boilers require (I believe) a powered inlet
air system. I’ve never seen a natural draft boiler on any of our projects and I’ve been in this business since 1999, or ~ 14 years, unless we were removing them, in which case they were replaced with new boilers that had the combustion inlet air fans. In
short, I don’t know why the Appendix G boiler is a natural draft boiler, I’ve always been curious about this, but using the natural draft boiler helps to show some savings versus more modern boilers, so I’m cool with it.<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 hope this is somehow helpful.<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">Thanks! </span><span style="font-family:Wingdings;color:#1F497D">J</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"><img width="717" height="418" id="_x0000_i1025" src="cid:image008.jpg@01CE514E.EACC2770"><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>
<div>
<p class="MsoNormal"><span style="color:#1F497D">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="color:#339966">JAH<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><i><span style="color:#339966">James A. Hess, PE, CEM, BEMP</span></i></b><span style="color:#1F497D"><br>
Energy Engineer<br>
TME, Inc.<br>
Little Rock, AR<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Mobile: (501) 351-4667<o:p></o:p></span></p>
</div>
<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""> Nick Caton [<a href="mailto:ncaton@smithboucher.com">mailto:ncaton@smithboucher.com</a>]
<br>
<b>Sent:</b> Monday, May 13, 2013 5:09 PM<br>
<b>To:</b> James Hess; <a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> RE: [Equest-users] Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">So, I see a number of logical paths forward for large 90.1 baseline boiler modeling. These scale in difficulty from a documentation standpoint, but each degree of effort can net additional potential for a better
performance rating:<o:p></o:p></span></p>
<p class="MsoListParagraph"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">a)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">[EASIEST] Conscientiously take a step back from reality and choose to not model any losses beyond flue losses. You can justify this decision by pointing at the fact 90.1 does not regulate nor set any
bar for non-flue losses in this highest capacity range, therefore none should be modeled (LEED CIR response language often follows this format). Procedure: Enter boiler HIR as 1/Ec for both baseline and proposed models.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">b)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">[LESS EASY] Assert your proposed equipment’s documented thermal efficiency, which includes non-flue losses and any means of mitigating/recovering those losses (i.e. jacket insulation, flue heat recovery
means) may be modeled as nothing in 90.1 precludes this degree of detail. In turn, opt to model the baseline without any such non-flue heat losses (or gains), as the means by which to do so aren’t prescribed. Procedure: Enter baseline boiler HIR = 1/Ec,
and proposed boiler HIR = 1/Et<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">c)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">[NOT AS EASY] Maintain the same difference in thermal vs. combustion efficiency between the proposed and baseline models, in keeping with Jim’s suggestion below. Example (using made up numbers): Proposed
boiler has a combustion efficiency of 88% and a thermal efficiency of 86%. Baseline boiler is prescribed to have an 80% combustion efficiency, therefore the same boiler equipment thermal efficiency should be 78% (2% non-flue losses). Conversely, if your
system’s thermal efficiency is an improvement over its combustion efficiency, the same logic holds your baseline should appreciate the same net efficiency gains. Procedure: Proposed HIR = 1/Et<sub> PROPOSED</sub>, Baseline HIR = 1/(Ec<sub>BASELINE</sub>-(Ec-Et)<sub>PROPOSED</sub>)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">d)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">[LEAST EASY] To permit the proposed system’s efficiency measures to be fully realized, identify the features NOT required by 90.1 or its referenced testing standards (haven’t done the legwork, but this
list may include stuff like flue heat recovery means, jacket insulation, and similar). Then, identify/document a real-world packaged boiler system of identical/similar capacity to the proposed equipment,
<u>excluding</u> those features, and still matching the prescribed minimum combustion efficiency. Document and cite this equipment’s thermal efficiency for use in the baseline model. Procedure: Baseline HIR = 1 divided by that thermal efficiency, Proposed
HIR = 1/Et.<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’s possible any or none of these approaches would be acceptable to a LEED reviewer for a given project, but anecdotally I have successfully used each mode of logic in other areas.
<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 long as we’re on the topic, I’d like to hear other’s thoughts on a closely related point – I’ve always matched my baseline boiler part load curve to my proposed equipment’s curve (whether it is sourced from
the library or “custom-rolled” to match real world equipment). Has anyone successfully used (and documented) different curves between baseline& proposed models for boiler equipment without a LEED reviewer taking issue? If so, on what did you base the baseline
curve?<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">Thanks as always for the great discussion!<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">~Nick<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#1F497D"><img border="0" width="119" height="37" id="_x0000_i1026" src="cid:image009.jpg@01CE514E.EACC2770" 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>
</div>
<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"">
<a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a> [<a href="mailto:equest-users-bounces@lists.onebuilding.org">mailto:equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>James Hess<br>
<b>Sent:</b> Wednesday, May 08, 2013 9:19 AM<br>
<b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">This is an interesting discussion.<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">Regarding the email below, I think that’s a reasonable approach. I also agree with the previous posts in this thread.<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">To add some more to this particular discussion … we know the two efficiencies are not the same, but I agree, getting good data on jacket/skin/radiation/convection (whatever you want to call them) losses or thermal
efficiency values is sometimes difficult to get.<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">Sometimes, we get lucky and it’s available. For example, Cleaver Brooks publishes a value of 0.25% of full load for the CBLE fire tube boiler product line.
<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">However, I can see those losses being much greater than that for different boilers, depending on the specific boiler design.<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">Also, for hot water boilers, you may get lucky and find both the Combustion Efficiency and the Thermal Efficiency in the following AHRI publication (there may be a more recent version available, not sure):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><img border="0" width="563" height="686" id="Picture_x0020_7" src="cid:image010.png@01CE514E.EACC2770" alt="cid:image001.png@01CE4B3C.1B9EDC80"><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><img border="0" width="835" height="433" id="_x0000_i1028" src="cid:image011.jpg@01CE514E.EACC2770"><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">I think you can see from that publication that the difference between thermal and combustion efficiency is sometimes significant, depending on the specific make and model of the boiler.<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">Also, you can check the AHRI online product directory<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><a href="http://www.ahridirectory.org/ahridirectory/pages/cblr/defaultSearch.aspx">http://www.ahridirectory.org/ahridirectory/pages/cblr/defaultSearch.aspx</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here’s an AERCO example … these seem reasonable; the Thermal Efficiency values are <= Combustion Efficiency values<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><img border="0" width="873" height="406" id="Picture_x0020_5" src="cid:image012.jpg@01CE514E.EACC2770"><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here’s a Fulton example<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><img border="0" width="864" height="460" id="Picture_x0020_3" src="cid:image013.jpg@01CE514E.EACC2770"><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">Some of these are not making sense, since Thermal Efficiency is > Combustion Efficiency for several of the entries<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">We know (or at least I thought we knew) that thermal efficiency should always be less than combustion efficiency, never greater, since thermal efficiency includes the flue losses plus the jacket losses. If that’s
true, then why does both the online directory and the publication show thermal efficiency values that exceed the combustion efficiency values ???<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">Perhaps AHRI has a different definition of thermal efficiency versus combustion efficiency ? Or there are misprints in the AHRI online directory and publication ?<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">Interesting …<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 also doesn’t make sense to me that ASHRAE 90.1 calls for Et for small boilers, but Ec for larger boilers. So we ignore the jacket losses for larger boilers, even though they are much greater? I think the
issue is that the AHRI IBR testing (i.e. ANSI Z21.13) only covers boilers up to 2,500,000 Btu/hr, then it’s the wild west after that, unless the larger boilers are covered by an ASME standard (not yet reference by ASHRAE) ?<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">One last interesting piece of info … the AHRI IBR ratings per ANSI Z21.13 are based on entering water temp conditions of 80 degrees, even for non-condensing boilers, even though operation at that EWT condition
would void the boiler warranty and destroy the boiler (i.e. condensing liquids dropping out in stack gas, then rusting out the stack and boiler). I’ve always been a bit curious as to why boilers are rated at conditions that they cannot operate at.<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">Any feedback on this would be appreciated.<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">Thanks! </span><span style="font-family:Wingdings;color:#1F497D">J</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">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="color:#339966">JAH<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><i><span style="color:#339966">James A. Hess, PE, CEM, BEMP</span></i></b><span style="color:#1F497D"><br>
Energy Engineer<br>
TME, Inc.<br>
Little Rock, AR<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Mobile: (501) 351-4667<o:p></o:p></span></p>
</div>
<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"">
<a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a> [<a href="mailto:equest-users-bounces@lists.onebuilding.org">mailto:equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>Jim Fowler<br>
<b>Sent:</b> Monday, April 29, 2013 11:39 PM<br>
<b>To:</b> 'Nick Caton'; 'Busman, Michael R'; <a href="mailto:equest-users@lists.onebuilding.org">
equest-users@lists.onebuilding.org</a><br>
<b>Cc:</b> 'The Watt Doctors - Dave Weigel'<br>
<b>Subject:</b> Re: [Equest-users] Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">I smile at this quandary (sorry…), having asked it myself, but not in the context of eQuest… I’ve rationalized that the combustion and thermal efficiencies are identical when the boiler is in a conditioned space,
because the jacket losses heat the space. I typically use a 1-2% downrate of the combustion efficiency to get to thermal, if the boiler is in an unconditioned space.<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>
<div>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:16.0pt;color:gray">Jim Fowler, PE, CBCP, CEA<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;color:#595959">++206-954-3614<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><img border="0" width="297" height="56" id="_x0000_i1031" src="cid:image014.jpg@01CE514E.EACC2770" alt="GEA logo cropped "><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#595959">Audits and Commissioning of Industrial
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#595959">Municipal and Commercial Buildings<o:p></o:p></span></p>
<p class="MsoNormal"><a href="http://www.globalenergyaudits.com/"><span style="font-size:8.0pt">www.globalenergyaudits.com</span></a><span style="font-size:8.0pt;color:#1F497D"><o:p></o:p></span></p>
</div>
<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"">
</span><a href="mailto:equest-users-bounces@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">equest-users-bounces@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> [</span><a href="mailto:equest-users-bounces@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">mailto:equest-users-bounces@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">]
<b>On Behalf Of </b>Nick Caton<br>
<b>Sent:</b> Monday, April 29, 2013 7:55 AM<br>
<b>To:</b> Busman, Michael R; </span><a href="mailto:equest-users@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">equest-users@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""><br>
<b>Cc:</b> The Watt Doctors - Dave Weigel (</span><a href="mailto:Dave.Weigel@thewattdoctors.com"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Dave.Weigel@thewattdoctors.com</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">)<br>
<b>Subject:</b> Re: [Equest-users] Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Mike – thanks a bunch for your response!
<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 can appreciate and relate to your experience with the boiler industry marketing folks… it’s very easy to get the run-around, and is often difficult/impossible to get information needed for modeling from product
literature. I’ve come to the same conclusion as you advised, and here’s my accounting/reasoning for those interested:<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 footnote in 90.1 Table 6.8.1-F defines combustion efficiency as “100% less flue losses,” so I that was the basis of this query. There’s additionally reference to this procedure:
</span><a href="http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&tpl=/ecfrbrowse/Title10/10cfr431_main_02.tpl">10 CFR part 431</a><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">That procedure defines combustion and thermal efficiency
</span><a href="http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&SID=bceba9fa026032bc4b393f9c462988bf&rgn=div8&view=text&node=10:3.0.1.4.19.5.54.2&idno=10">as follows</a><span style="color:#1F497D">:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><i>Combustion efficiency</i> for a commercial packaged boiler is determined using test procedures prescribed under § 431.86 and is equal to 100 percent minus percent flue loss (percent flue loss is based on input
fuel energy)<span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><i>Thermal efficiency</i> for a commercial packaged boiler is determined using test procedures prescribed under § 431.86 and is the ratio of the heat absorbed by the water or the water and steam to the higher heating
value in the fuel burned.<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">Clearly they’re not quite the same thing, where combustion efficiency does not account for jacket/standby/other losses affecting net output.<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 haven’t seen numbers to verify this, but perhaps ultimately jacket losses are
<u>such a small fraction</u> (at these largest capacities) that it’s accepted to be irrelevant. Put another way, the actual values for Et and Ec for boilers larger than 2.5MBtuh/h just aren’t very different.
<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">Running with that assumption, and unless anyone can answer further to this, I’ll treat baseline thermal and combustion efficiencies identically moving forward for large boilers: HIR = 1/Ec = 1/Et. If nothing
else, it’s a “safe/conservative” approach for LEED, in the sense that if there is an error of procedure here it is only artificially helping the baseline and would in turn prove a beneficial correction for the performance rating down the road.<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">Thanks again!<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">~Nick<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span style="color:#1F497D"><img border="0" width="119" height="37" id="Picture_x0020_2" src="cid:image009.jpg@01CE514E.EACC2770" 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"><a href="www.smithboucher.com" title="blocked::www.smithboucher.com"><span style="font-size:10.0pt">www.smithboucher.com</span></a><u><span style="font-size:10.0pt;color:blue">
</span></u><span style="color:#1F497D"><o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<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""> Busman, Michael R [</span><a href="mailto:MBusman@chevron.com"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">mailto:MBusman@chevron.com</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">]
<br>
<b>Sent:</b> Friday, April 26, 2013 1:47 PM<br>
<b>To:</b> Nick Caton; </span><a href="mailto:equest-users@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">equest-users@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""><br>
<b>Subject:</b> RE: Big Baseline Boilers - COMBUSTION efficiencies!?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<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>
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<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
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<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>
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<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>
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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"">
</span><a href="mailto:equest-users-bounces@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">equest-users-bounces@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> [</span><a href="mailto:equest-users-bounces@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">mailto:equest-users-bounces@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">]
<b>On Behalf Of </b>Nick Caton<br>
<b>Sent:</b> Friday, April 26, 2013 10:55 AM<br>
<b>To:</b> </span><a href="mailto:equest-users@lists.onebuilding.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">equest-users@lists.onebuilding.org</span></a><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""><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>
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<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:image009.jpg@01CE514E.EACC2770" 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"><a href="www.smithboucher.com" title="blocked::www.smithboucher.com"><span style="font-size:10.0pt">www.smithboucher.com</span></a><u><span style="font-size:10.0pt;color:blue">
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