[Stoves] Stratifying TLUDs for 'turn down'

[neiltm at uwclub.net]

Just had to share an almost comically successful breakfast cook this 
morning of porridge, done under an umbrella because of that immaculate 
timing of rain starting just as I've got the stove lit, coincidence that 
is only matched of course by rain starting the instant all the washing 
has been put on the line!

I cooked oat porridge, which simply involves bringing the oats and 
milk/water to the boil and then simmering for 5 minutes while constantly 
stirring to prevent burning.  (Burnt porridge is not nice.)

What I wanted therefore was for the stove to bring the pan to the boil as 
quickly as possible and then turn itself down at that point and simmer on 
a lower flame for 5 minutes.

The wood outside by now is sodden, when not actually frozen, but I still 
put a bottom covering layer of it in the Chinese wood gas camping stove, 
then progressively reduced the amount of wet wood in relation to 
perfectly dried wood from off the top of our boiler, finishing off the 
top third with dry wood only, for a good hot fire for the boiling stage.  
This I achieved to match in cooking time and performance what I would 
have achieved indoors on the gas stove, maybe even better.  I've boiled a 
full kettle in 10 minutes in TLUD mode from striking the match with this 
stove - it doesn't hang about getting going if the wood is dry.

No sooner than the pan had boiled, the flames licking up the sides of the 
pan disappeared bang on cue to give me my simmering flame.  Still a 
little more vigorous than I would have set on a gas stove just to begin 
with, but not a problem and it settled down very nicely for most of the 
simmer.  I will have to see if I can achieve more abrupt transitions 
successfully.

When I took the cooked porridge off the flame I could see that there was 
pyrolysis still going on right at the bottom, it was as if a flame from 
the bottom was working its way up through the glowing char above it, but 
the net result was a lovely simmer fire without the flare up at the end 
typical of a uniform loading of TLUDs.

Now I'm only a dilletante with these stoves, a regular/occasional user 
when I feel like it, which is usually whenever the weather isn't too 
horrible.  But although I will be honest and allow a margin for luck, 
because I don't always get it right, I did achieve what I set out to 
achieve for the cook.  It was only relatively recent experience of having 
loaded stoves this way quite a few times by now that gave me this 
control, so it occurs to me that where a cook is using these stoves all 
or the majority of the time, no matter what their local conditions and 
found fuel available, they will clearly be able to apply accumulated 
experience of the stove, the variability in their available fuel and what 
they commonly cook, to knowing just how to get the fire they want when 
they want it, even out of a fixed air ratio configuration stove, in a 
variety of ways, not just involving varying moisture content but fuel 
type and sizing also.

This is control that is potentially available with the simplest of easily 
fabricated tincanium stoves, requiring little more than a sharp point to 
make holes in tins.  At that level it is also possible to make a variety 
of stoves more suited to some specific cooking tasks with commonly 
available fuel than others.  Given the extent to which A TLUD stove is 
batch burn only, and the extent to which cooking tasks are repetitive, it 
is potentially easy to make these stoves optimally for such repetitive 
cooking tasks, and this I have done.  The only down side of the chinese 
ebay stoves is that it is not usually possible to limit the primary air 
sufficiently to prevent soot on the pan, but on the plus side, TLUD mode 
can be just a really great start to an indefinitely sustainable burn 
through continuing feeding the fire, a stage which also brings new ways 
to control the level such as allowing ash build up to partially choke 
primary air, or simply putting more or less wood on the fire.

I find pleasure and satisfaction in my own learning about woods and their 
preparation, and building the kinds of fire that I want, that I find hard 
to imagine is not potentially universal, even where there is no choice of 
fuel type for the cook. It is a satisfying learned skill. We are a 
perverse species in many ways.  Where there is third world poverty forced 
to burn biomass there is aspiration for lpg and electricity. Where there 
is first world wealth there is status amongst the wealthy rural dwellers 
in the UK in their 'Aga' range combined cooker, oven and water heater 
burning wood. Plus there is a growing interest in outdoor cooking on 
wood, wood burning ovens for bread and piza, even amongst caterers at 
festivals etc where the novelty (and taste) of cooking on wood pulls in 
the punters. In other words there is nothing intrinsically inferior to 
cooking with biomass, the differing statuses assigned to doing so 
depending on choice or its lack.

Poverty in the UK is a relative term to third world poverty, but the UK 
poor who experience 'fuel poverty' and therefore scarcity at the point of 
feeding pound coins they don't have enough of into gas and electric 
meters do sometimes choose to install wood burning stoves for cooking, 
space and water heating where a chimney is available, because there is 
usually no shortage of free wood to be found whether in urban or rural 
areas.  A second hand 'Rayburn' can sometimes be had for free, it being a 
cost in transportation and time to dismantle these heavy cast iron stoves 
where not wanted.  This depite their continued availability and 
desirability brand new, and at a high price.

Neil Taylor, in a sodden semi frozen England.