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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link="#0563C1" vlink="#954F72"><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 Kirk<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'>All that is well noted.<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'>I don’t have an answer for your last questions, but I do recommend that you do one of two things.<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'>If you have money, get a combustion analyser with a pressure meter measuring in 0.01 millibars and measure the draft directly between the primary air inlet holes and the fuel bed, or anywhere else you please.<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'>This is easy to do by soldering in a pipe where you want to make a measurement, even in a confined space, and connecting it to the combustion analyser sample pipe using a short piece of rubber tube.<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'>It is quite easy to get a draft of 0.20 millibars which means a 20:1 change on the display. <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'>Alternatively, get well-measured temperatures and the vertical distances between points of interest and enter the values in the Draft Calculator downloadable from this website. It will calculate the individual drafts of segments of the stove and give an overall total as well. The segments can be indicated as positive (+1) or negative (-1) depending on the flow direction. I think it accepts 5 or 8 segments, there are a couple of version floating around.<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'>Regards<br>Crispin<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>All,</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>It appears to me that the effect of ambient conditions on a TLUD-ND operating at low power is quite complex. The excellent responses to this thread have pointed to several possibilities.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>1. The heat loss from the stove and pot to the atmosphere is reduced because the temperature difference is less. (Thank you Prof Lloyd)</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>2. At higher ambient temperatures the primary and secondary air is effectively pre-heated before it enters the stove. This leads to a hotter pyrolysis front, faster wood gas production, and a larger secondary flame. (Thank you Crispin)</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>3. Higher ambient temperatures may be accompanied by higher humidity, which reduces evaporation from the pot. How does higher humidity effect the flame? (Thank you Crispin)</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>4. If I might add another, higher ambient temperatures are often accompanied by higher barometric pressure, which would increase the vaporization temperature so the pot will heat up slightly. It will also increase the vaporization temperature of the volitiles in the fuel, slightly increasing the fuel temperature. This may seem very small, but the stove operates on buoyancy pressure differences measured in single digit Pascals, so a change in barometric pressure may be more than the pressure differences that drive the stove.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>The total effect of a combination of these could be considerable.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>Kirk H.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div></div></body></html>