A central broiler wood furnace works by heating water using a wood-burning broiler and then passing the water through insulated piping throughout a structure to distribute the radiating heat. The type of wood used depends on the size of the broiler.
The heating mechanism for the broiler is an interior one, consisting of a metal firebox that contains the burning wood. The firebox is surrounded by the water. The heat from the fire is transferred to the metal of the firebox, which heats the water. Once the water hits a pre-set temperature, usually lower than the actual boiling point, the water is then pumped throughout the structure using the insulated pipes. The heat from the pipes is passed through heat exchangers and blowers to provide the heat for the structure. As the water cools during its loop through the structure, it is returned to the broiler for reheating and begins the loop again.
The heat is maintained by a damper that opens the firebox to allow fresh oxygen to keep the temperature of the burning wood high enough to continuously heat the water. Depending on the size of the broiler, wood used can be in the form of split logs to actual log rounds.