Burra Maluca wrote:This is the video.
I guess it would be a rocket stove, but not a mass heater.
I have to admit, I rather like this video, for the simple reason that up until last night I've totally failed to get my other half onto the idea of rocket stoves, but then I caught him watching this video. I'm discovering that he, like most men I know, much prefer it when they 'discover' things for themselves. I'm biting my tongue now and waiting for him to tell me that we're going to start experimenting - I think he wants to build one to test out the new still.
Mike Cantrell wrote:There's two problems.
The first, you already mentioned. Cinderblocks fall apart in fire. If you're lucky, they fall apart without popping hot pieces of concrete out onto your skin.
The second, though, is that it's not a rocket anything. It's J-shaped, yes, but that's not what makes something a rocket.
People get excited about rockets because they're efficient. (They get all the possible heat out of the wood, instead of leaving half of the potential unused as smoke.)
They're efficient because they're hot. (Above about 1,100F or so, the combustion becomes pretty complete. Everything burns, including the solids that would have floated up as smoke.)
They're hot because they're insulated. You insulate the heat riser (the vertical part of the J) so that instead of dispersing, the heat bounces around inside, heating up the smoke hotter and hotter, and moving the gases faster and faster. That faster movement gives you the whooshing rocket sound that the system is named for.
The J-shape doesn't make it a rocket. The insulation makes it a rocket.
So to put it all together: those cinderblocks aren't insulated. Without insulation, they won't reach extreme temperatures. Without extreme temperatures, they won't burn cleanly and efficiently. A stack of uninsulated cinderblocks is not a rocket stove.
Cj Verde wrote:This one takes more than a minute to make, but not much more. It's what they call a 16 brick rocket stove and it's better than the one above because you can use firebricks. I have one for heating up water for when I'm harvesting chickens.