It promises more heat from less fuel wood, a safer burn, and a bare minimum of pollutants released into the air we breathe. The upside down fire is built starting with the biggest logs on the bottom, progressing higher with continually smaller pieces of wood, until lastly the kindling and wood shavings or bits of paper are placed on top. It is then lit from the top and burns downward. Hardly a new concept, it originated in Europe hundreds of years ago as the fire-building technique of choice for the massive tile stoves widely in use.
This method produces a super-clean burn. The stove’s masonry mass soaks up the heat, releasing it slowly into the space for many hours from just one firing. A growing number of skilled stove masons are now building these heaters on site in new and remodeled homes. But the top-burn is not limited to masonry stoves. It is being employed in conventional fireplaces and stoves as well as in modular masonry refractory fireplaces.
The science and art of wood burning are as old as mankind. It is doubtful anything can erase from our ancestral memory the pleasure of building a fire, partaking of its warmth and watching it burn. The science of wood burning was given new impulse in in the 1970′s when wood heat came back in style. A few years later there was a hue and cry about the dangers of creosote build-up on flue walls. soon to be followed by urgent inquiry into the environmental and health hazards of wood smoke. The upside down fire addresses all of these concerns. The principle at work here is that as the bottom logs heat up and start to release their volatiles there is enough heat and flame above to ignite them.
Otherwise those first gases driven out of the wood travel unburned up the stack condensing out the highly-flammable creosote onto flue walls and spewing particulate matter into the environment. Creosote burns as hot as coal so its escape from the firebox is a loss of potential heat for the house. In the upside down fire all creosote burns up in the stove or fireplace.
The top-burn method can be quickly adopted for all types of fireplaces.
Place the largest pieces of wood at the bottom. For the best coal bed use dense hardwoods, this is the perfect place for those impossibly gnarled pieces and crotches. Graduate to layers of smaller softer wood in criss-cross crib fashion as you build it higher. The last layer should be the smallest possible diameter kindling. Place a few crumples of newspaper on top or better still use a handful of cedar shavings.
Refueling is not as critical a process as the initial laying of the fire. Add more wood when the crib of glowing coals falls in on itself. As long as you have a good bed of coals the firebox will be hot enough to heat up and ignite fresh fuel. This makes a dramatic difference in conventional fireplaces, producing a long clean burn and solving any start-up smoking problems.
A top-burn fire produces little or no smoke, there is a drastic reduction of particulate matter released into the air and virtually no creosote builds up on flue walls to pose a fire hazard. Masonry heaters, already noted for their clean burn now emit almost no smoke at all in that once-smoky initial 10 minutes or so of firing. Hopefully all conscientious wood burners will experiment with building an upside down fire in their fireplaces and stoves, and produce cleaner more efficient burns, helping us safeguard our families and do our part to renew this weary and abused old world.