Hello, someone just shared this with me so I'd like to post it here. It is very common in Korea and works in a very similar way to a RMH.
It looks like they typically have a brick chimney at the end of the line before sending flue gas to the atmosphere. I think the RMH style of putting the brick chimney *before* the long flue is an excellent improvement to ensure complete combustion of the smoke.
And, the underfloor heating is analogous to the thermal mass bench. If the bench spread to cover the whole floor it would effectively become underfloor heating.
I think this speaks to the cyclic nature of history. Something old has become something new again, to solve the problem of energy which went away with the utilization of fossil fuels, but has returned with the growing consciousness of peak oil and the end to the fossil fuel era.
My wife and I fly to Korea next week for a few weeks to visit friends and family and also give a presentation at the International Center in Gwangju about our contribution to the sustainability movement ...Kimchi Farm in Albuquerque, New Mexico. Ondol style is sure to be at least as popular as Gangnam Style! -Peter