Modern wood stoves are not simple metal boxes to burn fuel in. They are much more efficient than traditional fireplaces and can be just as attractive. Stoves also rely on a renewable source of energy. Most modern wood stoves fit into one of two categories: radiant or circulating.
Radiant wood stoves
As their name suggests, radiant stoves warm the home primarily through the heat they radiate when they operate. They are made from cast iron, soapstone, or welded steel. Although most of the heat is radiated, some is still passed to the air surrounding the stove and circulated through natural convection.
Radiant stoves are the more popular of the two types, mainly because they are the cheaper option (though there are extravagant models which cost more). They need fewer materials to manufacture and manage efficiencies in the 60% to 80% range.
Some radiant models come with extra options, such as top-loading to avoid smoke release or a thermostat to maintain room temperature by automatically regulating air flow and burn temperature.
Circulating wood stoves
Circulating stoves warm the home by heating the air and circulating it around the living space. Most circulating stoves look just like radiant models, with one difference: they are double-walled. And this is where the heating difference is implemented.
The inner wall is made of cast iron or welded steel (lined with firebrick, of course); the outer wall is made of steel. Between the two is a small air space. The stove's inner wall heats up when in operation and air in the space is warmed and passed out to the surrounding room. This can happen naturally, though many models come with a fan to push the air through.
Circulating stoves achieve efficiencies in the 60% to 80% range. Although they work primarily by circulating hot air, they do give off some radiant heat as well. However, the exterior shell never reaches the high temperatures of radiant stoves, so circulating models are often a better choice for families with young, inquisitive children.