I don’t recommend going out and paying $6000 for a wood-fired hottub, but Dutch Tub is a pretty genius idea for anyone looking for sustainable decadence. Works on simple convection: you build a fire inside the spiral of pipe, and the warmer water rises. Cooler water gets sucked into the bottom. You can insulate the fire for additional efficiency. Temperature is controlled by controlling the height of the fire-basket that is inside the spiral: raise it and less of the heating coil is heated. Granted, wood, while renewable, isn’t a resource that an entire global economy should depend on. But anyone who knows me knows I’m not interested in having a centralized global economy anyhow.
Heh,
I just saw this a few weeks ago at the Bauhaus (~home depot) among all the other hot tub, shower a.s.o stuff and although the design doesn’t fit my taste at all it does strike me as.. kinda nice.
Simpler version is going round at medieval fairs/markets – just a wooden tub about 2m in diameter with a copperpipe attached to it, part of which is coiled up(maybe other metal?) and placed in a fire on the ground nearby.
Ash
Since I saw this a few weeks ago, i’ve been pondering non-electric pump options for filtering. Without filtration or toxic chemicals, the tub would either have to be emptied and re-filled every few days or get nasty. Heated stagnant water is still stagnant water.