Dear Paul I concur that there are quite a number of things missing in stove comparisons. I have never seen published a lab report on the performance of the Vesto natural draft semi-gasifier save one test commissioned in Germany by Agnes Klingshirn. It has been on the market since 2004 and sold to at least a dozen countries. Jim Jetter has it in his current round of testing.
As you have seen yourself, one problem with new stove types is that it takes time to become accustomed to their operation, particularly their optimal operation. For common stoves the operation methodology is well known. Although the Vesto design is such that assembly is 'hard to screw-up' I have seen three times 'reports' on the Vesto showing that it was not correctly assembled, let alone correctly operated. There is an additional problem which is that the Vesto can be operated in a TLUD mode with pellets or chips or wood, TLUD (or not) with charcoal briquettes or wood charcoal as well as wood with a wide range of hardnesses. This means that it is not possible to classify the product with 'typical' emissions or performance because the fuels and operational methods are completely different and so are the results (well, in terms of emissions, anyway). As you know yourself, operating a TLUD with extremely dry fuel gives a completely different result from 15% moisture fuel. We recall the fuss you, quite legitimately, made when that happened. Roger Samson experienced the same thing for the same reason with the Mayon Turbo Stove. So I advocate the inclusion in a performance comparison of a clear description of the stove-pot-fuel combination that was used and avoidance of attaching simplistic generalisations to a stove. To be meaningful, performance has to be determined using a well-characterised burn cycle, cooking cycle, fuel and pot(s), whether expressed in relative terms or measured against a set of standard values. These days however, critical details are omitted and the stove given performance numbers that rather like those that used to be given to emissions from fuels, as if 'fuels' contain 'emissions' like PM2.5 and CO stored in little pockets waiting to be released. I also sympathise with your evident frustration at seeing stoves you know to be substandard relative to current knowledge and understanding. I have the same opinion about test methods and metrics! I was reading today how advanced VITA methods were in 1985. They were performing heterogeneous tests! It was only through project failure that we rediscovered how valuable and precise they can be. I hope that loss of progress does not happen to the better design aspects of the TLUD's. In a way you could say it has happened once already because of the lack of recognition in the enthusiast community (for decades) of the Silver TLUD stoves from Turkey, now rediscovered and applied by MCC/MCA Mongolia. The main point is we should do the best we can. I appreciate your freely sharing (and lots of others too) of a large body of knowledge about stove design and construction. Regards Crispin _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/
