How EPA Certified Wood Stoves Operate
EPA Certified Wood Heaters are a requirement in the U.S. The appliances that qualify as EPA-certified are the catalytic, non-catalytic, and pellet-fueled wood heaters which meet the particulate emissions limit of 4.5 grams per hour. As of February 2015, however, stricter standards were enacted. Within five years, all wood stoves and pellet stoves will be required to emit no more than 2.0 grams per hour of particulate emissions. Units that were installed in homes prior to the new rule are exempt.
How EPA Certified Stoves Work
EPA-certified stoves generally have a primary air intake and a secondary air intake. The way a reduction in particulate emissions is achieved is that exhaust gases are mingled with secondary air, which causes them to be re-ignited and to burn before going up the chimney. The stoves also create an environment in which there is increased burn time for the firewood.
In stoves with a catalytic converter, exhaust gases are channeled through a device, rather than being mixed with secondary air. In the device, the combustion temperatures of the gases are lowered. This way, the gases are consumed at lower firing. After a certain number of uses, catalytic converters must be replaced, which is usually expensive.
Stoves that are not EPA-approved have no catalytic converter and have only one air intake.
More about Catalytic Stoves
A palladium coating on the ceramic honeycomb –like converter is what lowers the ignition temperature of some of the smoke’s components, as it passes through the converter. Catalytic stoves are dependable when long, even heat output is desired. A catalyst bypass damper operated with a lever is included on all catalytic stoves, and it is opened both for startup and to reload.
The temperatures created inside a catalytic stove are extreme. At first, the temperature is about 550 degrees; but after about 20 minutes, the temperature reading is usually around 1400 to 1700 degrees, depending on how much wood is being burned, whether or not the wood is properly seasoned, and the size of the catalyst. A large flame is not required to create heat, when you use a catalytic stove.
The catalyst typically lasts six years, if the stove is used according to manufacturer’s instructions. If un-approved materials are burned in the stove, if regular maintenance and cleaning are neglected, and if the stove is over-fired, it is not unusual for the catalyst to break down within two years.
More about Non-Catalytic Stoves
Non-catalytic stoves have an air injection method in which pre-heated air is injected into a fire in order to ignite the smoke. The draft pulls hot-pre-heated air into tubing that runs across the top of the firebox. There are rows of tiny holes in each tube. Heated air ejects through the holes, creating jets that fan the smoke in the firebox.
Non-catalytic stoves are less efficient than catalytic stoves.
More about Pellet Stoves
Although pellet stoves look similar to other wood stoves, they are quite different internally. Pellet stoves do not burn cut logs. Instead, they burn small pellets about 1.5 inches long. The pellets are highly compressed and made with biomass wood waste, such as sawdust and other lumber byproducts that are typically thrown out with the trash. Pellet stoves need a small amount of electricity to operate. They are the most environmentally friendly type of wood-burning stove that you can buy.
Contact our chimney professionals, if you have any questions about EPA-certified wood stoves or to schedule an annual chimney inspection and cleaning.
Northeastern Chimney, Inc.
37 Cody Street, West Hartford, CT 06110