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<div name="BB10" id="BB10_response_div_BBPPID" dir="auto" style="width:100%">Dear Kevin</div>
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<div name="BB10" id="BB10_response_div_BBPPID" dir="auto" style="width:100%">I looked into this when developing the Vesto and there are two answers. One is the correct height (minimum?) Above the fire to get good draft to pull air into the fire at a high enough
velocity to get good mixing, and the flame space needed to complete combustion. </div>
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<div name="BB10" id="BB10_response_div_BBPPID" dir="auto" style="width:100%">For wood, I found the vertical space needed is at least 100 mm, with a preference for 110 mm, and for charcoal 50 mm with preference for 60 mm. </div>
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<div name="BB10" id="BB10_response_div_BBPPID" dir="auto" style="width:100%">You drawing shows two parallel rows of bricks. This should be two semi-circles in order to limit drawing in useless air. Cooling the flame with unnecessary excess air is a major cause
of PM with wood stoves and CO in charcoal stoves. </div>
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<div name="BB10" id="BB10_response_div_BBPPID" dir="auto" style="width:100%">Having a fuel hole and an air hole is important, closing everything else if possible. Putting a stone/pebble grate as you have been, is a great help. That allows incoming air to burn
the accumulating char, raising the combustion temperature. That of course reduces all emissions from incomplete combustion. </div>
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<div name="BB10" id="response_div_spacer_BBPPID" dir="auto" style="width:100%">Sheltering a fire on three sides is so-o much better than two parallel walls. So if they have bricks, even mud bricks as are common in the Eastern Cape, the result can be pretty
good. </div>
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<div name="BB10" id="response_div_spacer_BBPPID" dir="auto" style="width:100%">As a general rule, put the air entrance at the back bottom, opposite the fuel entrance, not on the same side as per rocket stove. It will keep the flame centered and away from the
walls. That plus >100 mm flame space will give a reasonable result. </div>
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<div name="BB10" id="response_div_spacer_BBPPID" dir="auto" style="width:100%">Keep up your good work!</div>
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<div name="BB10" id="response_div_spacer_BBPPID" dir="auto" style="width:100%">Regards </div>
<div name="BB10" id="response_div_spacer_BBPPID" dir="auto" style="width:100%">Crispin </div>
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<div id="from"><b>From:</b> kmclean56@gmail.com</div>
<div id="sent"><b>Sent:</b> July 22, 2022 9:41 AM</div>
<div id="to"><b>To:</b> stoves@lists.bioenergylists.org</div>
<div id="reply_to"><b>Reply to:</b> stoves@lists.bioenergylists.org</div>
<div id="subject"><b>Subject:</b> [Stoves] Space between biomass fuel and cookpot in an open-fire cookstove</div>
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<div class="gmail_default" style="font-size:small">What is the minimum distance from the top of the fuel to the bottom of the cookpot? I've heard that 8 cm is the minimum to get the best combustion.</div>
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<div class="gmail_default" style="font-size:small">We are training cooks to use common bricks to elevate two cookpots over one cooking hole. I want to make sure the cookpots are high enough.</div>
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<div class="gmail_default" style="font-size:small"><img src="cid:ii_l5wmil2u1" alt="2 burner drawing.jpg" width="253" height="196" style="margin-right:0px"><br>
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