Think of an old-time wood burning stove, and it's a box stove. A box stove draws air for combustion through the door, is not tightly sealed, has no damper control and releases a lot of unburned gases up the chimney. It's not safe to leave them unattended while heating, according to Ace Hardware.
An airtight stove has a sealed firebox and tight fitting door. This stove also has an air-intake damper that is manually operated or thermostatically controlled to let air circulate around the firebox and to control the rate of fuel consumption.
The relatively new pellet-fed stoves use a processed wood pellet, generally made from sawdust and wood shavings, fed into the stove's combustion chamber electronically. Pellet stoves have a steady and easily controlled fuel source, but the electronic controls don't work without electricity.
The potential safety hazards of wood-burning stoves include excess heat and sparks or flames that can cause a fire.
Traditional wood-burning stoves tend to emit a lot of gases, but pellet emissions are so small that the Environmental Protection Agency (EPA) does not even regulate them, according to Consumer Reports.