What Is Re-Burn Technology (Secondary Combustion)
“How does that work?” you might ask, as you watch the dark orange, almost red rolling flames cook inside a new wood-burning fireplace or insert. The flames hover and almost dance on their way up and out the flue, providing the owner with not only a small show, but the heat and warmth they expect.
The technology is both simple but technically advanced. Small air channels built into the appliance feed room pre-heated air into the firebox at calculated amounts, at different locations, which automatically ignite around 1,100 degrees Fahrenheit. The term re-burn, or secondary combustion, comes from the fact that you’re watching the fumes burn, or the “secondary” effect aside from the burning wood itself. An air control can be found on most models which gives the owner a choice as to how much air gets into the fireplace – more air means a faster fire, and less air makes it burn slower, for overnight burns.
The firebox itself inside the fireplace typically includes several pieces which all play an essential role in creating the re-burn effect. High-density fire brick, baffle boards, and even an insulated blanket on top are all designed to keep the fire inside the chamber longer, in order to achieve the 1,100 degrees required to burn off the gases. Once these gases hit temperature, a visual burning off effect can be seen at different sections where air is invited into the fireplace: Via burn tubes on top, glass air-wash systems in front, and primary air inlets located at the bottom or front. Once the fireplace hits this point, more fire can sometimes be seen coming from the re-burn effect than from the logs themselves.
The burning of these gases provides two main benefits. First, the gases burning off increases the heat output by the appliance by burning off wasted ‘smoke’ that used to typically go up and out the flue in old-fashioned models. The other main benefit is a cleaner-burning fireplace: That same smoke that used to billow out of the chimney is now burned off so completely that even the most stringent EPA regulations are met by most manufacturers. Because of the low emissions, today’s high-efficiency wood stoves, fireplaces, and inserts are technically carbon neutral – meaning they don’t pollute the environment any more than naturally rotting wood does in nature.
Re-burn technology has been in use for quite a while now, but more recent advancements have created products that both look visually stunning and provide people with a modern, tech-savvy heating solution. As homeowners look toward ways to be environmentally conscious and improve efficiency across the board, today’s high-efficiency wood-burners are hitting all the marks.