There are both indoor and outdoor wood boilers and furnaces. Outdoor boilers are really big wood stoves with a tank of antifreeze solution or water surrounding them. The burning wood emits heat to the fluid, giving hot water and energy to warm the house. The boiler temperature is regulated by a home control system. Most include an alarm for re-stocking. Furnaces provide warm air; they come as indoor units only.
Indoor wood furnaces and boilers are usually dual-fuel fired. They operate the same as outdoor models – the only differences are size, pollutant emissions and firewood consumption. The indoor dual-fuel fired boiler has the advantage of supplying heat even after the fire dies. The Benjamin model not only has a high-efficiency wood-burning stove, it also has an oil-fired burner that is used as backup when the wood-fired component does not produce enough heat after the burning cycle is completed. This is to maintain a consistent boiler temperature. You can also use fan-forced units that come with the typical central air plenum. Alternatively, hot-water boilers with hydronic heating can be considered.
The Specifics of Wood Heating
Wood heating systems are flexible in any home. The central warm air disbursement heating system is currently the most popular. A thermostat is used to control the furnace strength for heating the air chamber, then an electric fan is used to circulate the air using the hot plenum via ducts around the house. As the thermostat confirms the right room temperature, the furnace is automatically turned off to allow the home to cool before the next cycle commences.
A steam boiler or hot water system can replace the warm air in this system. Radiator units or hydronic pipes can be used to move the heat out to other spaces. A wood stove or masonry unit uses direct convection and radiation for its heat distribution.
The following are considerations for the type of heating system you would prefer:
- Is the renewable heating system a primary or supplementary heat source for your needs? A primary heat source requires backup heating systems, especially in cold climates.
- In more temperate climates, consider the renewable heating system as the primary heat source, preferring pellet or masonry heaters as these generate enough heat for at least a day. A longer heating period will require a re-stocking of the stove or finding an alternate heat source that has automatic activation controls for when the fire goes out.
- An off-grid heating system requires sufficient electrical energy to operate. Although convection wood stoves do not need electrical energy, they have to be attended to frequently. On the other hand, propane heaters do not need electricity while functioning as a backup source.
- Wood and pellets are cheaper than fossil fuels and less work is needed unless you harvest wood personally. A cottage that is heated by an old Franklin or cooking stove will not want to revert to wood as its primary heat source: too much wood is used without warming the place sufficiently and there could be too much smoke.
Wood stoves or heaters using wood