<html><body><div style="color:#000; background-color:#fff; font-family:garamond, new york, times, serif;font-size:12pt"><div id="yiv83495606"><div><div style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); font-size: 12pt; font-family: garamond, 'new york', times, serif; "><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span id="yiv83495606yui_3_2_0_32_132120191942778">Francois,</span></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span id="yiv83495606yui_3_2_0_32_132120191942786"><br></span></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span id="yiv83495606yui_3_2_0_32_132120191942791">I got an Envirofit stove </span>(G-3300) in the mail - the Western way to buy a stove - recently and have just started to benchmark it against other
mass manufactured stoves I have on hand. It is well constructed (though the fuel support and grate are on the flimsy side - but the support can be easily replaced with a brick), with a cast iron top, heat resistant alloy combustion chamber, and what appears to be mineral wool tightly packed into the ~8 cm space between the combustion chamber and the outer shell. It is easy to light and generally a pleasure to use (an important fuzzy metric?), but it sure seems to burn aggressively - despite the appearance of lots of excess air coming through the large front opening, the sticks immediately get so hot that the fire can quickly propagate out the front of the stove. The outside can also get a little hot - up to 75 C after 40 minutes at full power - I can't say if this constitutes a problem, and it cools off very quickly. The rest of this is commentary on my testing, in case that is of interest too (and we haven't had a list discussion of
stove testing recently) - you didn't mention what details about this stove might be helpful. Your other questions - if I can find enough wood ash I'll insulate it with that and test, since I often use it in plancha stoves, and the EcoZoom Dura Lite I am also testing has very similar construction, dimensions, insulation, operation, and performance characteristics. Early results when using sand as a filler are looking interesting!</div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span><br></span></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span>It takes a little time to learn a new stove so these are just preliminary observations, and anyway all cooks develop their own method - each balancing things like time to boil (via firepower), fuel conservation, smoke reduction, and ease of fire tending details
according to what they consider important - so you might well experience this stove differently. My own method is to operate the stove so that the firepower is relatively high (flames regularly spreading across the whole pot bottom, but none wrapping up the sides), my desires for both a fast time to boil and good fuel efficiency are balanced, and smoke is minimized. I follow common rocket stove fire tending practices - using only 3-4 sticks at a time, maintaining a few millimeters between them, and regularly breaking off the charred tips. Same as is shown in the Envirofit instruction video. I definitely pay too much attention to the stove while testing, since I am not doing anything else like cooking or rearing children at the same time, so that my results could represent something like the stove's best possible performance and not what you might see in the field.</span></div><div id="yiv83495606yui_3_2_0_32_132120191942748"
style="font-family: garamond, 'new york', times, serif; "><span id="yiv83495606yui_3_2_0_32_13212019194271344"><br></span></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span id="yiv83495606yui_3_2_0_32_13212019194271349">I used 10% moisture content coniferous wood (old shipping pallets - urban fuel), split into pieces of about 2 cm x 2 cm x 40 cm. I conducted 5 outdoor partial water boiling tests (</span>cold start segment only) with a different brand of pot skirt, using an average firepower of 3.8 kW (12 g/min, dry wood equivalent). An average of 33 minutes was
needed to bring 5 liters of water to a boil, requiring a specific fuel consumption of 83 g/liter and resulting in an average thermal efficiency of 30%. So far I am getting more test-to-test variation than I like, so average values are only somewhat useful - what is causing my distribution, and what does it mean?</div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; ">These are all corrected values - using the WBT 4.1.2 spreadsheet to take into account test-to-test differences in starting water temperature, water loss by evaporation, and wood moisture content. As most know there is regular debate over drawing conclusions from lab WBTs, so I just use the method at home for a cursory comparison of similar stoves, and for quickly evaluating the
potential impact of design changes to a specific stove. The WBT 4.1.2 spreadsheet usually produces results which are quite similar to those from version 3.0, and I'll be trying Crispin's heterogeneous protocol, since I already periodically record the change in water temperature during tests, to see if my target firepower is consistently maintained. It is definitely tempting to use a pot lid, after being laughed at too many times by cooks in the field when I insist that they do without one for my clumsy tests in their homes. </div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span id="yiv83495606yui_3_2_0_32_13212019194271367"><br></span></div><div id="yiv83495606yui_3_2_0_32_132120191942748"><span id="yiv83495606yui_3_2_0_32_13212019194271372" style="font-family: garamond, 'new york', times, serif; ">The Envirofit spec sheet and performance report </span>say that this stove
should have a thermal efficiency of 33% at its rated max firepower of ~3.7 kW - note that we can't make a direct comparison because they don't use the familiar WBT (either did I since I just brought the water to a boil - the rest is coming soon), and while I can't find out all of the details of their internal protocol (called EPTP - also 3 stages but using only 4 liters, and for the cold start it only brings the water to 90 C) I do try to run my tests close to their recommended firepower. Not having to reach boiling temperature would be fantastic, since that last degree or so takes considerable extra effort.</div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; ">After too many tests on other stoves I have almost run out my softwood supply so I'll have to switch to other
urban alternatives such as manufactured sticks (from dried dimension lumber), hardwoods I get from cabinet shops, or I'll start splitting our expensive local almond firewood. I'll be adjusting other variables as well, and would like to hear if other people are doing likewise - and what performance metrics you find most useful when making comparisons. </div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; ">Charlie</div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div
id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><br></div><div id="yiv83495606yui_3_2_0_32_132120191942748" style="font-family: garamond, 'new york', times, serif; "><span><br></span></div><div style="font-family: garamond, 'new york', times, serif; "><br id="yiv83495606yui_3_2_0_32_132120191942751"></div><div style="font-size: 12pt; font-family: garamond, 'new york', times, serif; " id="yiv83495606yui_3_2_0_32_132120191942754" class="yiv83495606yui_3_2_0_32_132120191942752"><div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; " class="yiv83495606yui_3_2_0_32_132120191942757"><font size="2" face="Arial"><hr size="1"><b><span style="font-weight:bold;">From:</span></b> François Sorba <fx.sorba@id-ong.org><br><b><span style="font-weight:bold;">To:</span></b> stoves@lists.bioenergylists.org<br><b><span style="font-weight:bold;">Sent:</span></b> Wednesday,
November 16, 2011 1:21 AM<br><b><span style="font-weight:bold;">Subject:</span></b> [Stoves] Envirofit
Stoves<br></font><br>
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--></style><div><div class="yiv83495606WordSection1"><div class="yiv83495606MsoNormal">Hello everyone,</div><div class="yiv83495606MsoNormal"> </div><div class="yiv83495606MsoNormal"><span lang="EN-GB">First I would like to thank all of you for your help regarding my question about wood ash as an insulator.</span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB">I have now another question regarding Envirofit Stoves.</span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB"> </span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB">Do you any of you have any previous experience with those stoves and this firm ?</span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB">What do you think of them ?<br><br>Do you know any other firm like this one (Prakti design ?)</span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB"> </span></div><div class="yiv83495606MsoNormal"><span
lang="EN-GB">Thanks!</span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB"> </span></div><div class="yiv83495606MsoNormal"><span lang="EN-GB">François</span></div></div></div></div><br>_______________________________________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br><a rel="nofollow" ymailto="mailto:stoves@lists.bioenergylists.org" target="_blank" href="mailto:stoves@lists.bioenergylists.org">stoves@lists.bioenergylists.org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br>http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br>http://www.bioenergylists.org/<br><br><br><br></div></div></div></div></div></div></body></html>