Outdoor wood furnaces, also known as outdoor wood boilers, are ingenious heating solutions that have gained popularity due to their efficiency and eco-friendliness. In this article, we’ll dive into the technical details of how an outdoor wood furnace works, offering a clear and concise explanation suitable for both technical and non-technical audiences.
The Basics of Outdoor Wood Furnaces
An outdoor wood furnace is essentially a standalone unit that provides central heating to your home or other structures. Unlike indoor wood stoves, which are located inside your living space, outdoor wood furnaces are installed outside, typically a safe distance away from your home. Here’s how they work:
Combustion Chamber
At the heart of an outdoor wood furnace is the combustion chamber. This is where the magic happens. The user loads the furnace with wood, and a combustion process begins. The key components of the combustion chamber are:
Firebox: This is where you place the wood for burning. It’s designed to withstand high temperatures and is lined with firebrick to ensure durability.
Draft Blower: A draft blower assists in controlling the flow of oxygen to the fire. This regulates the combustion process, ensuring an efficient burn.
Heat Exchange
Once the wood is burning, the heat produced needs to be transferred to the water. This is typically done in one of two ways:
Water Jacket: Most outdoor wood furnaces use a water jacket system. This involves a series of pipes or tubes that circulate water through the combustion chamber. As the water passes through, it absorbs the heat generated by the burning wood.
Plates or Heat Exchangers: Some models use plates or heat exchangers instead of a water jacket. These are positioned inside the combustion chamber and directly exposed to the flames. They transfer heat to the water that circulates around them.
Water Circulation
Once the water has absorbed the heat, it needs to be transported to where it’s needed, typically the house. This is accomplished by a pump or circulator. Here’s how this part works:
Pump: The pump, often called a circulator pump, pushes the hot water out of the furnace and into your home’s heating system, which can be a radiator, baseboard, or in-floor heating system.
Return Line: After the water releases its heat, it returns to the outdoor wood furnace to be reheated and the process repeats.
Control System
Outdoor wood furnaces are equipped with control systems to ensure efficient and safe operation. These systems typically include:
Thermostat: This is a user interface that allows you to set your desired indoor temperature.
Aquastat: An aquastat is a device that monitors the water temperature in the furnace. It helps maintain consistent heating by turning the pump on or off as needed.
Smoke and Emissions
Efficient combustion is crucial for outdoor wood furnaces. When wood burns, it produces smoke and emissions. To minimize the environmental impact, modern wood furnaces are equipped with features such as:
Secondary Combustion: This is a process that burns off the smoke and emissions produced during the initial combustion, increasing efficiency and reducing pollutants.
Emission Control Systems: Some models include advanced emission control systems, like catalytic converters, to further reduce the release of harmful substances into the atmosphere.
Conclusion
In summary, an outdoor wood furnace works by burning wood in a combustion chamber, transferring the heat to water via a water jacket or heat exchangers, circulating the hot water to the home’s heating system, and maintaining efficient combustion while minimizing emissions. This efficient and eco-friendly heating solution has made outdoor wood furnaces a popular choice for those seeking both comfort and sustainability in their homes.