Older, uncertified wood stoves can release 15 to 30 grams of smoke per hour, according to EPA’s archived stove-selection guidance. Wood smoke can worsen asthma and contribute to other health problems. The internal design of wood stoves has changed entirely since the EPA issued standards of performance for new wood stoves in 1988. Modern EPA-certified wood stoves burn more cleanly and efficiently than older uncertified models, but they still produce smoke and require proper installation, dry fuel and careful operation.
For new wood stoves, the federal particulate-emission standard is 2.0 grams per hour (g/h), or 2.5 g/h when tested using the optional cordwood method. These limits took effect May 15, 2020 and apply to both catalytic and non-catalytic designs.
Federal particulate-emission limits for new wood stoves
When comparing models, look for the permanent EPA certification label on the stove and check the EPA-certified wood-heater database. A lower g/h rating means lower emissions in the certification test; compare efficiency ratings separately. Also check for safety labeling by the Underwriters’ Laboratories of Canada (ULC) or another testing and certification body.
The two general approaches to meeting the EPA smoke emission limits are non-catalytic and catalytic combustion. Both approaches can meet EPA emission standards. Because they are slightly more complicated to operate, catalytic stoves are suited to people who like technology and are prepared to maintain the stove properly, so it continues to operate at peak performance.
Non-Catalytic Stoves. Three components make these stoves efficient: firebox insulation, a large baffle to produce a longer, hotter gas flow path and pre-heated combustion air introduced through small holes above the fuel in the firebox. The baffle and some other internal parts of a non-catalytic stove will need replacement from time to time, as they deteriorate with the high heat of efficient combustion.
Catalytic Stoves. These stoves produce a long, even heat output—thanks to catalytic combustion—in which the smoky exhaust is passed through a coated ceramic honeycomb inside the stove where the smoke gases and particles ignite and burn. Follow the manufacturer’s instructions for operating the catalyst bypass during starting and reloading. The catalytic honeycomb degrades over time and must be replaced; it can last more than six seasons if the stove is used properly. If the stove is over-fired, if inappropriate fuel is burned, or if regular cleaning and maintenance are not done, the catalyst may break down in as little as two years.
Sizing. Small stoves are suitable for heating a family room or a seasonal cottage. In larger homes with older central furnaces, you can use a small stove for “zone heating” a specific area of your home (family or living room). Medium stoves are suitable for heating small houses, medium-sized energy-efficient houses and cottages used in winter. Large stoves are suitable for larger, open-plan houses or older, leakier houses in colder climate zones.
Wood Matters. Dense or “hard” wood contains the most energy per cord and is the best choice for peak winter conditions. Burning softer woods during swing seasons keeps rooms from overheating. Regardless, EPA’s archived burning guidance recommends seasoning wood for at least six months and testing it before burning: moisture content should be below 20 percent. Check a freshly split face with a moisture meter; elapsed drying time alone is not a reliable test.
Pellet Stoves. Pellet stoves use compressed pellets (made from wood or other biomass) for fuel and can be used in either fireplace inserts or free-standing stoves. They are categorized into two types, based on the pellet delivery system. Top-fed pellet stoves direct pellets into the combustion chamber from the hopper at the top of the stove. The combustion chamber is more likely to be filled with ash and other debris. Bottom-fed pellet stoves feed pellets into the combustion chamber from the bottom and automatically push the ash into the ash pan. Cleanup requirements depend on the model and fuel. Pellet stoves can be convenient to operate, but require regular cleaning and maintenance. Unlike wood stoves, pellet-burning involves no cutting, less hauling, no splitting, stacking or waiting for wood to dry. If used correctly, pellet stoves produce very little smoke or creosote, which can cause chimney fires. Most pellet stoves need electricity to run their feed systems and fans; check the model’s backup-power provisions. Follow the manufacturer’s cleaning schedule and arrange professional cleaning at least annually. EPA’s archived pellet-stove guidance explains these requirements.
Before buying, check installation requirements and wood-burning restrictions with your local building department and air-quality agency. Follow the stove’s installation instructions and required clearances. Keep combustible materials away from the appliance, and never burn trash, painted wood or pressure-treated lumber.
Updated content · October 16, 2026