Here is a walk through of a Non-catalytic wood stove. I took a picture of a cutaway display model stove so I can show you what the inside looks like.
We will follow the path that the air takes for combustion. First the air is drawn into the stove at the bottom. This is where the damper controls how much air is allowed to come into the stove.
Next the air travels up along the air chambers on both sides of the stove and gets preheated before it comes into the firebox.
Each manufacturer does this next part a little differently, with varying degrees of success. I would talk to an experienced salesperson or see the fire burning before you buy. This picture shows the “Air Wash” which is where the air comes into the firebox down past the glass. This keeps a “curtain” of air moving between the glass and the fire to keep the glass staying clean.
Next your main combustion happens which is burning up all but roughly 100 grams per hour of fuel.
That unburnt fuel hits these “Re-burn Tubes”. There is a little bit of secondary combustion are drawn in from another location outside the stove. When that fresh oxygen mixes with those unburnt particulates and the temperature is hot enough they will re-ignite. This secondary combustion is what makes the stove EPA certified and have an average of about 3 grams per hour of emissions.
Lastly the air flows forward in the stove then back past the top plate to pick up the absolute most heat it can before it exits up the chimney system.
This is how an EPA certified wood stove functions.
The cutaway that I walked you through here is a Country Stoves Striker 160, made by Lennox Hearth Products.
The Stove Guy