paul wheaton wrote:A rocket stove is for cooking outdoors.
A rocket mass heater is used for heating your home.
paul wheaton wrote:The math on how they are so much more efficient is spelled out at http://www.richsoil.com/rocket-stove-mass-heater.jsp
The great thing about a rocket mass heater is that not only does it heat your home with 1/10th of the wood, but it requires far less fooling with than a conventional wood stove. If nothing else, you have 1/10th the wood to fool with. But even better is that you can burn a fast hot fire in the evening and then you're done. The house stays warm through the night with no further fire. You wake up in the morning and the house is warm - no need to start a morning fire.
Keep in mind that a rocket mass heater leans heavily on radiant heat and conductive heat - which are both far more efficient than convective heat. Also keep in mind that most people run their conventional wood stoves in a way to try to make the fire last longer. So while their stove might be rated as 75% efficient, they might be getting only 10% efficiency. Or worse.
Marc West wrote:Hi all,
Firstly, to answer the original poster: there is an encapsulated PCM material called "Micronal" made by the German company BASF:
but I appreciate that that post dates from a couple of years ago...
I have a slightly different enquiry, and I wonder if anyone can help.
I co-own some land with a small community, and we wish to build a cobb wall on it, partly to provide support and warmth for trees like apricots and peaches. (We are in Cardiff, Wales, UK). Now, it has long seemed to me that incorporating PCM in the cobb structure would be a great way to extend the warm period at the end of a hot day. I've just read this thread and realise that paraffin wax in tins embedded in the wall may be just the thing. (Thanks to Frank R for his clear posts!)
The issue for me, then, is to find a paraffin wax that melts at the right temperature, which I guess should be in the region of 22 degrees C or so, for it to be most use for extending the warmth of the day for plants. (Anyone have a better guess?). Now, as I understand it, paraffin wax has a melting point of between 46 and 68 degrees C (variable because paraffin wax is not a single substance but a mixture of compounds [called 'alkanes'] of the form CnH(n+2), for example C25H52). So using 'ordinary' paraffin wax wouldn't be any use, because its melting point would be too high.
So how to get a lower melting point paraffin wax-like substance?
2 possibilities occur to me:
1) mix in or use some shorter chain alkanes. Ought to work fine, but looks like it will be a lot more costly than standard paraffin wax is;
2) Dissolve something into standard [inexpensive!] paraffin wax to lower the melting point, in rather the way that dissolving salt in water lowers its melting point (which is what we do to ice to make it melt when on driveways etc). Does anyone know what substances can be dissolved in paraffin wax to lower the melting point? Salt? Some other "more organic" substances that will dissolve better? I'd be happy to experiment with a thermometer and a saucepan of the stuff in a water bath, but I don't really understand how to calculate the likely effect on melting point of dissolving a certain quantity of material X into paraffin wax.
Not being a chemist, I don't really know where next to go with this. I'd appreciate any thoughts you guy may have on this. Or if someone knows of affordable off-the-shelf paraffin wax substances with melting point in the right range perhaps they could let me know.
Thanks in anticipation...
Rion Mather wrote:I'm on board with hybrids. I'm obviously no expert but there are big differences between rocket stoves and Rocket Mass Heaters, including the vertical and horizontal feeders/burn chambers. As far as masonry stoves go...there are numerous styles to choose from. You should check out youtube. I have found it to be the best place to learn about stoves, in general.
allen lumley wrote: Frank R.: While there are stoves that can be run nearly as efficiently as a rocket stove, and new ones being ''rushed to market'', the new owner soon teaches themselves
how to 'load that dirty bastard up.' ' to let it burn all the day without taking up any more of my time ' ! ! i.e. burning dirty and inefficiently, like my neighbors ! The worst
ones are the ones that deliver domestic hot water, they smolder along 24-7, 52 weeks of the year to guarantee a hot shower at will 24-7, 52 weeks of the year !
I will make a General statement that while the Rocket Stove has a major draw back, that it needs frequent attention to run at its most efficient, that this is the only way
that the Rocket Stove can be run! This is also its biggest asset, forcing you to burn it in its most efficient manner, or get smoked out of house, or left with a cold house !
Living with a Rocket Stove and its hungry Dragon is a life style commitment! If you are not willing to live this way, the Rocket Stove is not for you! If someone has to be
'out of the house' to be 'the Bread Winner', then they most spend 6-8 hrs prepared to and attending on their Rocket Stove To get 20-25 hrs of heat stored inside their
Thermal Battery,or have a Partner willing to assume that job ,or deal with a cold house !