Slide 2:
Wood burning stoves and fireplaces have been used indoors for centuries, providing heat long before we knew about the centralized gas burning systems of today. Masonry heaters are essentially fireplaces that are very effective, and are often used for cooking as well.
They burn wood in an enclosed firebox and the fuel is a maze of firebrick or stone that moves all around inside the large masonry structure so that all the heat is put to use and is stored in the brick. One load of wood, after it is burned off will pack away enough heat in the bricks to heat an area for hours.
Also incorporated in these designs are vents for natural convection, using the principal that heated air rises, these vents allow for air from a room to be circulated and heated, and naturally increasing heating potential.
Slide 3:
The first design for this was by Benjamin Franklin in the design of his Franklin stove. Modern wood burning stoves use these techniques as well as other to give you the cleanest emissions, most heat production and most effective heating methods possible.
The Environmental protection agency first started to regulate wood burning stoves due to the excessive amount of particulate matter that was produced by them (40-60 grams or more per hour) that can potentially cause cancer.
Also, other than unburned wood, the combustion can result in unburned carbon monoxide which requires at least 1200 degrees to burn off. Modern EPA wood burning stoves use several different methods to keep unwanted gases and particles from being released. The two major designs accepted for a more efficient wood burning stove is catalytic or non-catalytic.
Slide 4:
A catalytic wood burning stove uses a catalyst that when it becomes hot enough, you close the damper forcing all the exhaust through it, the temperature will rise to over 1000 degrees, thus creating a cleaner burn. A non-catalytic wood burning stove uses secondary air put into the fire box from above, adding more oxygen for the fire unburned gases and particles in the exhaust to be burned away.
Also a non-catalytic wood burning stove will use a baffle that holds the exhaust near the fire for an extra fraction of a second so that it becomes hotter while secondary air is added. If the fire is not hot enough, when you turn on the secondary air nothing will happen, an effect use of secondary air will show if the flam is larger.
The EPA is actually offering tax rebates on the purchase of one of their qualifying wood burning stoves. You can see a list of some of the wood burning stoves that qualify at choosefireplacesandstove.com or get more information about tax rebates for a wood burning stove at the EPA Energy Star Program website. This program offers up to 30% return of the purchase price up to 5,000 dollars.