[Stoves] ash layer beneath fire

[Crispin Pemberton-Pigott]

Dear Vincent

 

It will help a little. What would really help your overall fuel consumption
however, applies to all stoves of this type which have a flat bottom and no
grate.

 

Put a metal grid grate at the bottom, elevated perhaps 10-15mm. That takes
up very little vertical space. The grate can be reused if the clay is
exchanged, or replaced if it wears out.

 

Try this: Use straight 12mm round bars. The spacing of the bars should be
16mm centre to centre. This is a lot more bar material than one is usually
offered and there are good reasons for that. Make it the same diameter as
the hole, minus a bit to drop it in easily and either provide a mud/clay
ridge around the bottom to elevate it or give it a few short feet.

 

Then use the stoves as normal. What you are looking for is clear evidence of
the production of less charcoal. If the char has support from below, it will
burn properly instead of smouldering in the accumulated ashes. It can
increase the total heat available by as much as 25% in a typical cooking
cycle. The gap under the grate provides for an element of preheating of the
primary air which increases the completeness of the charcoal combustion.

 

Whether the bottom is made of ash or loose-but-packed clay will make little
difference to anything.

 

Regards

Crispin

 

 

Hi.

 

Could anyone help me out with this - would an ash layer beneath a fire in an
improved cookstove (as in the sketch attached) help insulate the fire and
prevent heat loss into the body of the stove? The layer would be about an
inch thick after compression, and is about half an inch below the base of
the stove.

 

Thanks,

 

Vincent Okello

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