[Stoves] Mongolian traditional clay stove

[Crispin Pemberton-Pigott]

Dear Andrew

>I presume the shot at the end showing the smoky modern metal stove against the clean flame from the newly built clay stove was to tell us something.

The metal stove is a traditional model in used for about 120 year. It is ultimately based on a Russian design. It is a great wood stove though not a very good dung burning stove.  All stoves that burn dung, save a few, are smoky, because they are not idealized. 

The metal one in the video is the unit we are trying to get rid of in Ulaanbaatar.  Owners take a pretty good wood stove and line it with bricks to prevent excessive heat damage, then fuel it with coal for which it is hopelessly inappropriate. Lignite actually. 

>Tell me if the fibres in the dung are to give the clay strength as it dries presumaby once it's fired they severe no further purpose ...

As explained very briefly in the vide, the fibres prevent or largely prevent cracking during drying.  As you can see, the plates are assembled as soon as they can be stood up - this is far from ideal.  It would be better if they were sub-baked and heated to 500-600 C in a pit using grass for fuel. 

>...and the clay is held together as earthenware byt the point contact partial vitrification?

Yes.  Similar cookers can be made using termite mounds where the inside gets vitrified but the outside never gets hot enough to change at all. 

The curious extra piece that the author doesn't know about is possibly one of two things: an air guide which means that the stove is probably built in a way that the piece is headed into or away from the wind, or it may have a spiritual function and always faces East, or South. 

The tray on which the yak dung is pre-loaded is most interesting.  Is it the first time people have seen such a device attached to a stove?  It allows the fuel to be metered into the chamber "at will" and will provide a certain amount of drying (hence the metal). 

Yak dung is a widely used fuel.  In the Pamir region of eastern Tajikistan, it is the only fuel, save a little oily bush. 

Regards
Crispin