[Stoves] TLUD before 1985 needs documentation

[Crispin Pemberton-Pigott]

Dear Paal

 

With reference to the Only TLUD stove(s).

 

Here is a practical problem:

 

In Ulaanbaatar we have two stove on the market, one well established, one
new, which are vertical cylinders. The better known one is not advertised as
a TLUD, it is sold as a coal stove. They both have an inside about 30 cm
across. 

 

People light established one like this: a wood fire in the bottom and when
it is going they add coal on top. As it is a high volatiles coal, it makes a
great deal of smoke (evaporated volatiles) until the flame is established
above the cold coal. After that it is quite clean burning. It has primary
and secondary air provided.

 

The other one is a TLUD with a capacity of about 12 kg of coal. It is filled
with coal then top-lit using wood. There is really little difference between
them except the newer one is made from cast iron and the established on from
mild steel.

 

Both stove will operate in TLUD mode or bottom lit mode. There is nothing
really unique about the construction that enhances one type of burning over
the other - it is purely the choice of the user which method they want to
use.

 

In both cases, if the stoves are refuelled, there is a great deal of smoke
because the new coal is placed directly on top of the existing fire.  

 

Are both stoves TLUD's if they can be operated that way? Are they both
BLUD's because they will inevitable be refuelled that way?

 

There are a lot of the established stoves in use - not sure how many, but
plenty because they are available with finance from a commercial bank.

 

How a stove is operated is apparently more important than how it is built so
giving a name that intends to say how it is used might help, or it might
discredit the method when people do not follow it.

 

Another example: there is a traditional stove that is lit as described above
but it is a rectangular box. If the fire is instead lit at the chimney end
and the fire burns towards the loading door, it reduces smoke emissions by
about 80%. This is a TLUD running on its side. It is end lit and cross draft
(ELCD). The stove remains unchanged - it is only a difference in how it is
used. The two combustion methods, bottom lit side-draft and end lit
side-draft, work in completely different ways but the stove is identical.

 

Thus I am doubting the 'only' can apply to just about any stove other than
as a recommendation as to how it is intended be used.

 

Even then, the manufacturer's recommendation for the two round stoves are
not the same. And in fact the way we ran the stove during testing (to
optimise the performance) was not either of the recommended methods because
both are sub-optimal.

 

The cross-cutting of the log is a really good idea. Same fuel, same ignition
materials, completely different combustion method and performance.

 

It seems we still have a long way to go.

 

Regards

Crispin

 

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