>Funny how we have a post here from some company selling these and it feels like the thought is "this is new". Yes. Related: Russian stove: https://en.m.wikip

>Funny how we have a post here from some company selling these and it feels like the thought is "this is new". Yes. Related: Russian stove: https://en.m.wikipedia.org/wiki/Russian_stove https://en.m.wikipedia.org/wiki/Russian_stove And this article show that many of these variants are related, and that the basic principle is very old, even prehistoric: https://en.m.wikipedia.org/wiki/Masonry_heater https://en.m.wikipedia.org/wiki/Masonry_heater