[Stoves] TLUD-ND Test results by Jim Jetter was Re: FW: ETHOS 2013: Where is t

[Crispin Pemberton-Pigott]

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