That is essentially a modification of a Russian or Ukrainian samovar (lit. self-or auto-brewer). The principle is the same except that in a samovar, the firebox and chimney are self-contained, whereas this needs a fire below it.
This is a pretty slick contraption if you ask me. Excellent design and efficient use of resources. Simple to use and maintain. Not often anymore that you run across something like this. I am very impressed with the whole concept. Thanks for the additional information.
What a cool little device. I really like how efficient it is, I will have to accidentally email these web addresses to my wife around say, Fathers day
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Brian.