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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Dear Paul and Other Stoves testers<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>From Paul: “</span>As I understand the WBT procedures, doing this would result in more favorable efficiency numbers than if the pot was boiling vigorously on the full impact of the fire, and losing much water.”<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The thermal efficiency is a stove when simmering, based on missing water, is not a scientifically valid calculation so there is no point trying to improve your score on it. For any given burn rate, the performance of a ‘more efficient stove’ (meaning heat transfer efficiency is better) will perform <i>worse</i> when rated by the GACC-WBT method (please differentiate). The better the stove is in real life the worse for the rating on emissions and fuel consumption. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The problem is the metrics chosen for rating performance. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal>Can someone please confirm this for me. And perhaps give an example where the ONLY VARIABLE THAT CHANGES IS THAT THE POT BOILS OFF SIGNIFICANTLY LESS WATER if the pot is placed to the side. I am thinking of the difference in the amount of water in the pot being even 2 or 3 liters less between the two examples.<br><br><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you boil less water, the assumption is you have transferred less energy, right? Well, that is no problem if the task at hand is to keep a pot hot. If the performance is measured by evaporating water, then that is a different task. I.E. set one task, but rated on another. Problem.<o:p></o:p></span></p><p class=MsoNormal><br><span style='color:#1F497D'>></span>Yes, these types of stoves could exist, as in an example of a TLUD without any turn down of primary air and with a pot support that allows the pot to be shifted to the side (such as on 2 pieces of rebar).<br><br><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Turning down a stove by any means is advantageous in that you might have a stove with a turn down ratio of 1.5 and the local community wants 3:1. Yes it will waste fuel, but you might be really fuel efficient at other times and make up for it.<o:p></o:p></span></p><p class=MsoNormal><br>When we have clarification about this, we can then discuss if moving the pot should be a factor in stove testing. And also if the amount of remaining water after simmer should be a factor. <br><br><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Simmering (if asked to do it) is a task, an arbitrary one. There is no point in measuring how much water is in a simmered pot – either it is simmering on low power or it is not. The use of water before and after for ‘simmering calculations’ is a red herring and has misled many people into thinking there stove was doing worse or better. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The only useful info you can get while simmering (apart from the fact of being able to do it) is the emissions with time and the heat transfer rate, which cannot be determined on the basis of missing water, only rising water temperature from cold. That means using a cold pot at low power, not keeping a hot pot boiling, almost. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>It is an easy test to do and provides useful information.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Crispin <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></body></html>