[Stoves] DIY camping TLUD with walnut shell fuel

[neiltm at uwclub.net]

On 14 Jun 2016 at 16:17, Mangolazi wrote:

> Hi Neil, thanks for the recommendations. I think I'll get one of
> those cheap Chinese stoves to see what they can do. Most of them
> look the same so I assume they're all from the same factory. 

They do seem to be all the same.  The main difference between them is in 
which type of pot support/concentrator top you choose.  There are the 
fold out sort, with a gap between top of concentrator and pot of 2cm, and
the fixed higher rise top (4.5cm) with open side that permits easier fuel
feeding without removing the pot.  I have both, and now prefer the latter
as the increased height between secondary air holes and pot makes for a 
slightly cleaner burn, and interferes less with the draught.  It has 
closer support points though, although I have yet to suffer instability 
from that.  All the parts between the two stoves, bought years apart, are
interchangeable.

> They're
> also rather squat - more power, less run time? 
> 

They are squat, but run time really depends on the fuel.  It is about 10 
mins of towering inferno run as a TLUD with dry wood, but double that and
up to half an hour with moister/denser/larger fuel, and I've read an hour
with pellets, but haven't tried that.

Depth of fuel chamber to centre of secondary holes is 85mm.  Internal 
diameter is 110mm (122mm external).  Its a decent practical fuel chamber 
size, making fuel preparation in the wild easier.  With the high rise I 
imagine it is very similar to the Bush Buddy, but that is smaller over 
all.

They are not sold as TLUD stoves but as wood gas camping stoves, but the 
architecture is the same as a TLUD and runs very well in that mode. The 
secondary air gap behind the holes is only 8mm, but the secondary air 
flow is certainly not lacking. 

They are very easy to use by say holding a match under an upside down fir
cone in the bottom of the stove, and then placing more fuel on top - 
cones or twigs.  You can simply build a smaller fire from the bottom 
that, or in any other way, if you want less heat.  It is possible to lose
the flame as Kirk describes when very low, but that usually only happens 
in these stoves from increasingly ash congested primary air which a 
stirring stick can very quickly remedy bringing the stove back to 
vigorous life, or just tickling along as you choose.  His suggestion of 
lower pilot holes for enhanced turn down is one I would definitely 
experiment with if making new tin can stoves though.  At the moment I am 
enjoying my fuelling learning curve to see how good my heat control can 
become, and so far the experience has been so encouraging as to cause me 
to stop taking my two Reed fan stoves on camping trips, relying now 
entirely on the two chinese stoves (and a kelly kettle) because I know 
they will be easier with more difficult fuel.  Incidentally 3 days ago, 
the kelly kettle boiled 2 litres of water in two batches from wood that 
was dripping wet, once I had made a good start from my cache of dry.  It 
surprised me.  I lost the wet bark off some thicker branches/twigs I 
split with the aid of a pair of secateurs to reach the dryer heart wood, 
and burnt these in conjunction with thin pine brash just as it was.  It 
was a strong and fairly smokeless burn too.  No starter additives of any 
sort, not even paper which I never use. Techniques for kelly kettles are 
a whole other fascinating and rewarding subject, and I even use the kelly
kettle on the chinese stove base for the coffee and washing up water 
after cooking a meal.  That is just too easy!  

> The main reason I want to throttle primary air on tiny tincanium
> stoves is to allow some turndown for simmering. Right now, I have to
> boil something first on wood gas flames and then simmer on the
> leftover char. It would be nice to get a long flame burn time from a
> small can. 
> 

All I can do is repeat that you can achieve this with trial and error by 
controlling the fuelling with these stoves, and from the sound of it 
yours, from the similar characteristics you describe.  You have already 
reported the difference in burn time and heat output from different fuels
- you could try exploiting these differences further to see if it gives 
you the heat you want when you want it, the way I seem to be increasingly
managing, and especially in the wild where immediately found wood might 
be damp or even dripping wet, whereas I also maintain a bag full of dry 
starter, and this you can mix to suit . Its a learning curve, just as 
cooking on an open fire is, and would be no less with a turn down lever 
controlling primary air, just a different set of factors to understand 
and master. The first time I used the chinese stove as a TLUD in the 
Pyrenees where the fuel was very dry, the flame was about the two feet 
high and the pan I was frying in caught fire, but I soon worked out ways 
to obtain a more useable heat, but even that meal wasn't spoiled.  You 
can go from a robust TLUD boiling heat to a gentler simmer still on 
feeding in wood, but things you have to watch out for are approaching the
end of a potential fools paradise of thinking that you have really easy 
control, (which you do for a while, and maybe long enough), when in fact 
this is masked by the consumption of all the char from TLUD mode which is
about to leave you with no fire base to add fuel to if you're not 
careful.  This is where just enough riddling can keep good control over a
simmer heat potentially indefinitely, as can poorer or damper wood.  The 
char stage is really also quite vigorous with all that primary air, 
giving off a lovely blue flame to begin with, but it will soon be all 
gone without refuelling, but still lasts long enough to make a slice of 
toast or maybe two.

> I'm still amazed how so much heat can come from a tiny amount of
> fuel, especially compared to a campfire. Learned that the hard way,
> grabbing a not-quite-cooled can after a test run... 
> 

I agree it does seem amazing, and that as you say such a 'squat' stove, 
the pot standing a mere 6 inches off the ground can have such a fierce ND
heat under it, and just how much heat there is in so little fuel.  When I
was a boy scout at camp, each patrol used to make several forays with a 
treck cart and felling axes to bring 'enough' wood back to cook for about
8.  Issued with these stoves, one cart load would probably have served 
all 6 patrols for the duration!  

Best wishes,   Neil Taylor