[Stoves] Wood-ash as insulator

[Crispin Pemberton-Pigott]

Dear François

 

The best answer I have found so far is that sand needs to be graded to a
narrow size range in order to have insulation properties. What you want you
avoid is having lots of little particles to filling the spaces between
larger ones. It depends on where you are when looking to such sand. If you
are in a place near a windy beach, that would be the place to get single
sizes. In Northern Mozambique there are lots of sand dunes and they contain
almost only one size! Even though there is unlimited sand, it is hard to
make concrete products because of that issue.

 

You can buy two round brass sieves from a soils laboratory supplier, for
example 1.15mm and 2.0mm. Throw out everything larger than 2.0 and use
everything sitting on the 1.15mm screen. That will have much less heat
conduction that the original (mixed) sand.

 

Remember that even when compacted, it will have no strength at all. Zero.

 

Regards

Crispin

 

 

++++++++

 

Hello everyone,

 

I am currently trying to build a wood saving stove (rocket stove model). All
the info I gathered are saying to use wood-ash as an insulator between the
outside layer of sheet metal and the L-shaped combustion chamber.

 

Do you know if I could replace wood-ash by anything else ? Something easy to
come by
 Something like dry sand for instance ?

 

Thanks!

 

François

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