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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'>Dear Darren<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 link <a href="http://www.hearth.com/econtent/index.php/wiki/Downdraft_Stove_Operation/"><span style='color:#1F497D;text-decoration:none'>http://www.hearth.com/econtent/index.php/wiki/Downdraft_Stove_Operation/</span></a> has an explanation of how one of the Crossdraft stoves works. There is quite a lot of confusion about what is a downdraft and crossdraft and the instructions are so complicated one is forgiven by not working out what is going on.<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'>Part of the operating instructions are related to the fact he is using a large masonry chimney and the compensations needed have nothing to do with the way the stove works, in principle.<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'>Many downdraft and crossdraft stoves have a bypass to get the chimney started. A lot of work has been done in the past two years at the SeTAR Centre in Johannesburg on how to avoid the need for this, in order to make the device and operation simpler. <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 layout of the Resolute Acclaim 1988 stove (above link) is nearly identical to the GTZ-7 series stoves being made in Ulaanbaatar for burning coal. The main difference can’t be seen in the cross-section: the combustion chamber in the Resolute (and many similar coal and wood burners made in Europe) is much wider than the front-to-back depth. It is the dramatic narrowing of the combustion chamber from the wide fuel hopper that is responsible for the very low PM emissions of the GTZ-7 series stoves. The width is 80mm whereas it is common for the Resolute style stove to have a combustion zone that is the same width as the fuel hopper.<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 wide burning zone allows what Tom Miles calls ‘sneakage’ of CO and smoke into the chimney when not operating at full power. You can see there is a small amount of secondary air provided by the Resolute at the bottom right of the picture. That is essential as well because of changing hopper conditions.<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 SEET lab in UB has developed very low emission ignition methods which are much easier (and better) than the one described for the Resolute. The stove is made to optimise the methods. I described it earlier as basically a TLUD start.<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'>Attached are two stove tests showing the PM 2.5 and mass of fuel burned. The first is pretty much like a typical ‘grandma’s cast iron cook stove’ and the second is the TLUD lit crossdraft GTZ-7.5 showing what is technically possible with a change in the lighting method and the hardware. In both cases the stoves were new and operated well.<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'>If you want to build something, go with the Resolute layout but if you like I can send you something about the better placement of the heat exchanger and how to avoid the need for a ‘bypass’ and complicated lighting. <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 digging snow in Waterloo<o:p></o:p></span></p></div></body></html>