Wood burning stoves are known for their efficiency in heating homes while utilizing a renewable energy source. One of the key factors contributing to this efficiency is secondary combustion. In this article, we will delve into the technical details of secondary combustion in wood stoves and why it matters.
What is Secondary Combustion?
Secondary combustion is a process in which wood gases and particulate matter that are not fully burned during the primary combustion phase are reignited and burned a second time. This occurs in a dedicated secondary combustion chamber or zone within the wood stove. The result is increased heat output, improved fuel efficiency, and reduced emissions of smoke and pollutants.
Technical Details
Here’s how secondary combustion works in a wood burning stove:
Primary Combustion: In the initial phase, wood burns in the firebox, releasing gases, volatile organic compounds, and particulate matter. Some of these components do not burn completely and are released as smoke.
Air Injection: In stoves designed for secondary combustion, fresh air is introduced into a separate combustion chamber above the primary firebox. This air is preheated as it passes through channels or tubes, which can be found in some stove designs.
Reignition of Gases: The preheated air is introduced into the secondary combustion chamber, where it ignites the unburned gases and particulates in the smoke, resulting in a second burn.
Heat Recovery: As these gases and particulates burn, they release additional heat energy, which is then transferred to the stove’s heating system or radiated into the room. This is what makes secondary combustion so efficient.
Benefits of Secondary Combustion
Increased Efficiency: Secondary combustion significantly improves the efficiency of wood stoves. It allows for more complete combustion of wood, extracting as much heat as possible from the fuel.
Reduced Emissions: By burning unburned gases and particulates, secondary combustion reduces the emission of pollutants and minimizes the environmental impact of wood burning.
Longer Burn Times: Stoves with secondary combustion can offer longer burn times from the same amount of wood, reducing the need for frequent reloading.
Less Creosote Buildup: More efficient combustion leads to reduced creosote buildup in the chimney, decreasing the risk of chimney fires.
How to Identify Stoves with Secondary Combustion
Stoves equipped with secondary combustion typically have certain features that set them apart:
A secondary combustion chamber or zone: Look for a separate chamber above the primary firebox where secondary combustion occurs.
Air controls: Many stoves with secondary combustion have adjustable air controls to manage the airflow, allowing you to optimize combustion efficiency.
Baffle or refractory components: These help direct the flow of hot gases and particulates to the secondary combustion chamber.
EPA Certification: Stoves that meet Environmental Protection Agency (EPA) standards often incorporate secondary combustion for reduced emissions.
In conclusion, secondary combustion in wood burning stoves is a technical process that greatly enhances the efficiency of these heating appliances. It not only increases heat output but also reduces emissions and contributes to a cleaner and more environmentally friendly wood burning experience. When considering a wood stove for your home, look for one with secondary combustion features to enjoy its many benefits.