Its going!
All of the smoke tunnel / basic structure is done, and its been burning for the last three hours or more!
I had a bit of trouble with smoke escaping from cracks in the cob/between mud bricks, etc., partly from making cob without much attention to the clay/sand ratio. The bench still needs a bit more height, and then several finishing coats of cob to seal cracks, and finally lime plaster will go on.
There is a bit of a problem that somewhere in the chimney there is a hole or crack likely from rats in the past-- the particular chimney was not used for perhaps two decades or more and I found corncobs in it-- such that when the stove is starting and the smoke is much cooler and heavier it finds its way through some rat tunnel and out a crack in the plaster in another room!
At the last minute, I added the cubby-hole, which I'm going to put a door on, as a place to culture yogurt, kombucha, sourdough, etc-- hopefully it will just at that point get warm and not hot. I put 4 thermocouples into the flue system, so the last time I checked, the first one (where the smoke leaves the barrel and enters the flues) was showing about 85°C and the last one (about a meter before the smoke leaves out the chimney) was showing 40°C.
Here is an album with construction photos up to where I am burning it today:
Materials cost was:
2 bags of perlite -- 13€
16 white, ordinary bricks -- 5€
Cleanout fittings -- 10.50€
Hydrochloric acid -- 3€
Silver stove paint -- 2€
Large bolt and nut to plug hole in barrel -- 2€
500kg of sand for cob/earth plaster -- 12€
Total cash outlay-- 46.50€
The barrel was given to me by a neighbor with a scrap yard, the clay roof tiles and sheet metal (used as form for heat riser) were from when we did our roof (standing seam replaced the old clay tile roof-- hundreds of old clay roof tiles stacked in our yard), rocks and concrete chunk infill were waste from previous demolition/reconstruction projects, plywood was recycled from a shipping crate-- so no cash outlay for these things. Clay of course is free-- just my labor to dig it out of the ground.
For lime plaster there'll be a bit more cost...
Of course, a simpler design would have needed only two cleanout fittings, etc...
I wanted specifically to go as low cost as possible, even though I could afford other materials, because I want to show an example for poorer Slovaks and gypsies what they can do for less than they can buy a cheap chinese stove (150€ or so).
Cover the feed hole with a brick does indeed flame outs once the fire is going good.