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New Emission Limits for Solid Fuel Heating Equipment to Begin May 2020

Products that do not meet these EPA updates may not be produced or sold after May 15, 2020. This article shares all the updates you need to know.


March 30, 2020

A wood-burning stove is a heating appliance capable of burning wood fuel and wood-derived biomass fuel, such as sawdust bricks. Generally, the appliance consists of a solid metal closed firebox made of cast iron or steel and often lined by firebrick plus one or more air controls that can be manually or automatically operated. The first wood-burning stove was patented in Strasbourg in 1557, two centuries before the Industrial Revolution. Even though they were made of relatively common and inexpensive iron, such stoves were high-end consumer items and only gradually spread in use over time.

How the U.S. is working to protect the environment

In today’s world, emissions related to wood-fired appliances are covered under the “Clean Air Act,” a federal law established in 1963 to control air pollution on a national level. The Clean Air Act requires the Environmental Protection Agency (EPA) to set limits for air pollution generated by wood-fired appliances because it could endanger public health and welfare. The law also requires the EPA to review the standards every eight years.

In 1988, the United States Clean Air Act required that wood stoves be certified by the EPA. These devices must meet an emissions standard of no more than 7.5 grams per hour for non-catalytic wood stoves and 4.1 grams per hour for catalytic wood stoves. Washington State has stricter requirements of a maximum of 4.5 grams per hour. However, the EPA has had no mandatory emission limits for pellet stoves, indoor or outdoor wood boilers, masonry stoves, or certain types of wood stoves that are exempt from EPA regulation.

New updates from the EPA

On May 15, 2015, the EPA changed the emission limits and required that wood-fired stoves, pellet stoves, wood-fired inserts, forced-air furnaces, and hydronic heaters meet emission standards of no more than 4.5 grams per hour. This was the first step in creating the New Source Performance Standard (NSPS) that the EPA developed in partnership with industry. The second step in the process, which becomes effective May 15, 2020, requires pellet stoves, wood-fired inserts, forced-air furnaces, hydronic heaters, and wood-fired stoves meet stricter limits, as shown below:



Wood and pellet stoves tested with crib wood

2.0 grams per hour

Wood and pellet stoves tested with cord wood

2.5 grams per hour

Forced-air furnaces

0.15 lb/mm/Btu

Hydronic heaters

0.10 lb/mm/Btu


Products that do not meet these limits may not be produced or sold after May 15, 2020. To confirm that a unit is in compliance with current EPA regulations, refer to the marking affixed to the unit indicating the compliance date.

How UL can help

We can help you manage this intricate process and improve your speed to market. We are accredited by the EPA as a Third-Party Certifier. This means we will review test data and reports generated by the EPA Accredited Test house which carried out the testing. Finally, we complete our report and deliver it to the EPA for review and fulfillment.

Avoid disruption to your business and ensure compliance of your products. Contact us at [email protected] or visit: