Outdoor wood-fired boilers are an alternative way to heat a home using lumber or wood pellets. These boilers are located 30 to 500 feet from the home and can be used with any pre-existing heating systems.
The combustion chamber where the wood or wood pellets are burned is encased by a water jacket. This water jacket works with a heat exchanger to heat water, which is then transported to the home via insulated piping underground. Once in the home, this hot water can be used with a variety of heating systems through a water-to-water or water-to-air heat exchanger. Direct circulation of the hot water into these systems can also work to heat the home, and a single boiler has the capacity to heat multiple buildings at the same time. In addition to heating buildings, outdoor wood-fired boilers can provide a direct source of hot water.
Some issues associated with outdoor wood-fired boilers include the incomplete combustion of the wood and excessive smoking by the unit. As temperatures drop, so does the temperature of the water jacket surrounding the combustion unit. This is an unfavorable condition to burn wood and thus much of the wood does not combust. Cold temperature also results in more smoke, as the cold steel encourages condensation of smoke-producing creosote.