How do wood stoves achieve such high-efficiency ratings?

If you buy a new wood stove today, it must comply with the Environmental Protection Agency’s (EPA) 2020 New Source Performance Standard emissions for clean air. This standard requires manufacturers to limit emissions to 2.5 grams/hour or less for cordwood.

The overall efficiency rating of today’s modern wood-burning stoves is in the low 70% to 80% range. These efficiencies are met in a couple of different ways. The engineering and design of wood-burning equipment utilize re-burn systems designed into the appliance. Secondary burn tubes and/or catalytic combustors are used to burn any smoke created from the fire. By burning the smoke, you’re getting a bit more heat out of the wood used. But more importantly, the emission rate is less than the 2.5 grams/hour standard.