Some models utilize air drawn from inside the home, while some use air drawn in from double-walled pipe from the outside. The exhaust gases are vented up the center tube, and the fresh air is drawn from the surrounding casing, eliminating the dangers of low oxygen levels in an airtight house. Gas Log sets can be used both for heating or purely decorative flames, available in vented and unvented styles, again offering the ambiance of a wood fire. Mess Free Wood Stoves are offered in freestanding, inserts, and complete fireplaces, in a variety of colors and finishes and glass doors. Gone are the pot-belly stove days where you added wood or coal every hour, since efficiencies have risen so much, that a 10 to 12 hour burn time is not uncommon.
Catalytic stoves use a ceramic honeycomb structure that has been coated with a rare metal catalyst.
The combustor is built into the stove in such a manner that a bypass is opened during startup to allow chemical reaction that forces the carbon monoxide to burn at a reduced temperature. Catalytic combustors, by design, degrade with time, thus reducing their performance. Under extreme firings of the stove, they may crack and fall apart. They can also be ruined by paint on wood, or paper and ink. Non-catalytic stoves are not, by design, prone to degrade.