Wood-burning heating systems of all types use wood as fuel. While they are not as popular as gas, oil and electrical options, they give people with access to trees effectively free heating.
Fireplaces are a popular option even for those with other heating options. Fireplaces are relatively easy to maintain, and their simple design means that there are few ways for them to fail. However, fireplaces lose most of the heat they generate through their chimneys, which, combined with their inefficient combustion, makes them poor choices for primary heating in colder regions.
Wood stoves are similar to fireplaces but provide more efficient heating. Their metal construction allows them to heat a relatively small space effectively. Still, much of their heat is exhausted through the chimney, making them similar to space heaters.
Wood-fueled furnaces and boilers are often placed outdoors, which lets them hold more wood and capture more heat. The heat they generate is then spread throughout the home, enabling more consistent heating. While some heat is still lost through ventilation, more efficient combustion allows users to generate more heat with the same amount of wood. Outdoor placement also means that wood-burning furnaces and boilers pose almost no risk of carbon monoxide or smoke poisoning, although laws may regulate their use due to the high amount of particulate matter they generate.