I used to futz around with these as a kid, and picked up a few useful pointers.
1) There is still a lot of native coal in the US, and a lot of states have outcroppings of it where you can just help yourself. Almost nobody looks for it or imagines that it is useful, but if you know where some is, it can save a lot of wood chopping.
2) A cheap set of bellows can get your fire hot and ready much quicker, especially with sub-optimal fuel. They are commonly sold as home fireplace decorations, but never used by most people, yet they work.
3) Always keep a squirt gun handy to cool a fire that is too hot.
4) Fires produce three kinds of useful heat. Convection heat from hot air, which is fast; Conduction heat in things that conduct heat, like metal and liquids, which is somewhat slower; and Infrared heat given off by conductors, which can last for hours. If fuel is scarce, it is important to remember and try to use all three.
Most Americans aren’t too familiar with using Infrared heat to heat an area, but the concept is an old one, and widely used where fuel is scarce. On the large scale, it is used in “oven stoves” or “tile stoves”. (great web page, btw, with lots nice pretty pictures):
http://www.lowtechmagazine.com/2008/12/tile-stoves.html
Most people don’t want to lug around stone blocks to absorb the heat of their fire and give it off as Infrared, however, but there is an easy solution: It works just as well if you use sand or powder from these high energy density stones.
In order of energy density, from high to low, is gypsum, soapstone, basalt, marble, limestone, sandstone and granite.
So bottom line, instead of using just sand as insulation for your oven, use common, inexpensive gypsum powder, that can be found in any garden store. It will absorb lots of heat, acting like a good insulator, and then give off Infrared to heat the area around it for a long time.
A small amount of fuel can do a lot if you don’t waste it.
“Masonry Heaters” - use the concept of the rocket stove - high temperature, high draft, high efficiency
to heat a huge mass of masonry brick up fairly quickly, and letting it radiate the heat for several hours after the fire dies.
More info:
http://mha-net.org/
Good information.... Thanks .