Creosote is often a problem when you add water coils to wood burning chambers or flues because the water absorbs a crazy amount of heat and lowers the volatile gas temperatures until they won't combust. The smoke particulates fall out of the flow and build up on the sides of burn chambers and flues as un-burnt tar. That stuff can later be burnt off with a rapid blaze, but then you have problems with flue fires as that gunk burns off. So boiling water with wood needs a hotter flame all around. Still those folks did get 3 years of hot showers with a very simple set-up, and it's interesting to see how it looked when they deconstructed it.
Also, I totally understand the strong guidance against adding pressurized water boilers to rocket mass heaters. These mass heaters are DIY earth-hacker designs and water-heater pressure-valve fiddling is almost always designated a professional plumber's domain. If you are going to influence the masses of people to make stuff like this in their homes, it is wise to spread caution about the differences in risks. Putting a bunch of mud around a burn box is a lot less risky DIY project than plumbing a close-system boiler.
get schwifty. tiny ad:
A rocket mass heater heats your home with one tenth the wood of a conventional wood stove