[Stoves] ***SPAM*** Modified Cinese Retail TLUD Camp Stove

[neiltm at uwclub.net]

Andrew's post taking me to the bioenergylists.org main page and seeing 
Jim Tisso's modifications to the Chinese stainless steel ND camp stove I 
use, prompts me to write with a different suggestion for modifying the 
primary air to reduce soot and towering infernos with close to zero 
moisture wood, especially after having conducted a recent experiment that 
underlined for me how advantageous that would be.

Firstly, I don't agree that the stove is designed for too much primary 
air.  I think this is to mistake its primary purpose which is as a 
lightweight portable camp stove for burning found wood, and which will 
inevitably come with varying degrees of moisture, especially in colder 
wetter climates. The very similar bush buddy uses a quite widely spaced 
wire grate, so even more primary air.  Ditto the solo stove which copies 
it.  Only if in an arid zone with consistently very dry fuel, a 
perforated disk, which could even be a sacrificial circle of card, or a 
few washers dropped onto the grate, restricting the primary air might 
serve as a semi permanent modification for such an environment.

Secondly, soot is really not that much of a problem, given that it can 
easily be wiped, brushed or washed off the pot, and the pot can be 
carried in a plastic bag to contain the black.  It's not been a problem 
for us a month away at a time.

Thirdly, a lot of primary air makes for an easier start to the burn, 
without the need for risers etc., especially with less than perfectly dry 
wood.  Then when underway the flame might be optimal and smoke free, 
depending on the moisture content. If there is variety in the fuel 
available it can be mixed to achieve the sort of burn you want. A small 
cache of very dry wood might be carried, just to start the pyrolysis 
front which quickly reaches less dry found wood. This is obviously easier 
to arrange at home.  If you are relying entirely on one stove when 
camping then getting it lit under all conditions and sustaining a 
reasonable heat, trumps every other consideration and this is where this 
stove excels.

The other day at home I loaded the stove vertically with totally dry 
split hardwood, but then sprinkled some very fine woodchip - chainsaw 
sawdust sized, and let that trickle through the gaps.  This sufficiently 
restricted the primary air throughout the burn that it extended the time 
of the burn very usefully, while still being easy to light, and 
maintained a nice medium heat.  I cooked a full English breakfast for 
two, and with the kelly kettle replacing the pot stand and concentrator, 
boiled water for two large mugs of coffee, all without reloading, and 
then had to wait half a minute or so for pyrolysis to finish before 
'quenching' a full stove of char in the biscuit tin.  Never got that much 
out of a single charge before in this stove.  It really highlighted that 
mixing damp wood with dry, while that can achieve the length of burn and 
size of fire wanted, it undoubtedly comes at the cost of wasting some of 
the energy drying the wood.

It prompted me to come up with a way to control the primary air at will 
throughout the burn so that I might maximise the benefits of burning 
close to zero moisture wood, and obtain useful turn down in general.

I never cease to be impressed by the design, and the great versatility of 
this stove -  the number of different fuelings and loadings I have 
successfully experimented with.  That versatility is IMO a prerequisite 
of such a stove, but which would be severely compromised by a permanent 
modification to reduce the primary air, in the absence of perfectly 
consistent dry fuel.  But how to make it variable without adding 
significantly to weight, its packed size when telescoped down, and its 
basic unmodified characteristics, ie. the availability of unrestricted 
full draft?

Further down the bioenergylists page I came to Robert Fairchild's 'steam 
pan charcoal stove', and he uses precisely what I had in mind as a mod 
for the grate, which is as simple as it gets, except that successful 
execution presents some challenges, for me at least.  

The simple lever would extend through the bottom air holes of the outer 
shell, with the space between two of them removed.  In his illustration 
the two metal faces are nicely snug, but then it doesn't look as if the 
stove had actually been fired!

With both my Chinese stoves the grates are by now quite buckled and not 
at all flat after much use, and even showing some signs of burning out 
with splits.  So I would have to start with a brand new stove, and then 
manage to cut the diamond holes in a disk without buckling it in the 
process, something I have already tried and dismally failed to achieve.  
Then it could quickly become no good if the plates buckled from the heat, 
creating significant permanent airways.

It occurred to me that I might succeed better if I had another pot of the 
same diameter, (4", 10cm), that I could cut down, leaving a sufficient 
lip to face downwards and stabilise the disk sufficiently to make for a 
good enough seal to sufficiently prevent permanent airway gaps that 
prevented a fuller restriction of the primary air.  It would not have to 
cut off all primary air obviously, just enough to achieve a useful 
minimum.

So far I have not managed to find anything suitable, an ordinary tin can 
unfortunately does not have a flat base, so the seal would be 
compromised.  But I might try it anyway, since nothing much to lose.

I can imagine that properly manufactured as a version of this stove it 
could be executed well, and that users would need to know no more to 
benefit from it than that it is a lever to control the desired size of 
the flame, but start it fully open, then turn down as desired.  

I would be interested in any DIY suggestions or if a manufacturer might 
consider such a modification?

Best wishes,    Neil Taylor, 'locked down' in England