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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Dear Darren<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>This is coming along well.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>></span><span lang=EN-US>Some photos are attached.<span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Got them, thanks.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><br><span style='color:#1F497D'>></span>The door and hatch are made and have fire rope seals. <span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Good move. The hopper should have no air passing through it. There is a pyrolysis zone above and near the primary air entrance, then a burning zone further to the left (back of the grate) then a gas burning zone above the rear of the grate ascending into the vertical chimney.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>></span><span lang=EN-US>I've used a cast iron grate from an old coal stove that was the perfect size.<span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>It looks really. I think you should expect to make two changes once you get going. One is to decrease the gap between the grate and the ceramic bridge (we found 75mm is perfect for the fuel we are burning) and to increase the 10 degree angle as a means for achieving this. That means lifting up the front or near end of the grate. What would make you want to try that would be excessive smoke caused by too much fuel burning at once. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>We ran quite a number of tests with different spacings like 65, 70, 75 and 85 and 90mm but all having 10 degrees of slope. The 75 mm straight line distance was perfect. It gave an excess air ratio of 80-120% and extraordinarily low PM values for much of the time. Because your fuel is different you are going to have to do some hit and miss too until you get a really clean flame about 15 minutes after ignition and thereafter, no smoke. Hopefully it will perform as expected.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><br>*At the moment all the secondary air is going in through some square section pipe with an internal diameter of 20x20mm that enters at the rear of the combustion chamber above the ceramic blocks. (shown as blue square in stove2-7.jpg). Is this going to supply enough air or should I put a similar sized secondary air inlet on the front of the stove also?<br><br><span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>This si going to be a very difficult question to answer without equipment. Suppose you have enough air but your 100mm grate gap is too big. It might incline you to provide more secondary air when you really needed to reduce the burn rate. At some point, you have enough power, so the air to match it is ‘X’ value. At a higher or lower burn rate, you need a different amount. You are gonna tell us what you need! I think the 20 x 20 may be too much but the fuel is different. The easy test is to open and close it when there is only a little smoke. It should make very little as it transitions from one firepower to another as it lights up. Somehow the feedback from you hand closing it will tell you which way to take things.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>If you can’t see any need for it, close it totally. It just add air with no effect other than to cool the output gases. If you need it, leave it open. We have not found any need to adjust the secondary volume when it is running. Most of the secondary air enters through the far end (back) of the grate where there is less fuel.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><br>*Crispins GIZ design has an area where the combustion chamber tapers wider (an expansion chamber?). I've drawn this in green in stove2-7.jpg . How important is this? <span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>The expansion is important but not critical. If you can, do it. Professor Lodoysamba found that filling the combustion chamber with wood and top-lighting it provided immediate heat for cooking, very low emissions and easy ignition (automatic) of the fuel under the hopper. Very clever.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>When the fire reaches under the hopper, he had to shake the grate to move fuel down onto the grate. That is all in terms of attention.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>></span><span lang=EN-US>What effect does it have on combustion? what would happen if I leave them out?<br><br><span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>The effect of the bricks/ceramic is to improve the combustion by having hot walls. If you can’t get real refractory bricks second hand, use the hardest clay face bring you can find. It will last the longers in terms of off the shelf material.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><br><span style='color:#1F497D'>>…</span>Hopefully I should finish and test fire it in the coming week.<br><br><span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Looking forward to more pictures and your comments.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>></span><span lang=EN-US>I've attached a diagram of how I'm now planning to build the grate and throat area. (I took the liberty of modifying the GIZ diagram Crispin kindly sent to explain an appropriate layout) <br><br><span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>You construction matches the drawing.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><br>As I'm only going to be burning wood and in my experience of wood stoves all the wood burns to a light ash which would easily fall through the grate I am planning to have a stationary grate. Am I making the wrong decision here? <br><br><span style='color:#1F497D'><o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>The grate gaps look large which will create extra charcoal that might get snuffed in the ashes. Other than that it is fine. If the grate turns out to be too ‘coarse’ you can drop in a set of 12mm steel reinforcing bars welded into a grid. Works fine.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><br><span style='color:#1F497D'>></span>Hoping to get it finished soon. Considering the number of people I've been describing it to all year it would be good to also let them know how it works!!! I've never seen anything like this in action - I'm thoroughly intrigued. <br><br><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>You are going to have to try it with charcoal briquettes, wood pellets, wood, chopped up wood, coal and switchgrass cubes if you want us all to be happy! Good luck.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>