How does recirculation work?

[WarmGuy]

My understanding is that non-cat stoves are efficient because smoke is blown back over the fire, where it will burn -- so called "secondary combustion."

Can someone explain the design of the tubing, baffles, etc, that causes this to happen? I'm assuming that somehow the inrushing intake air draws a portion of the smoke with it??

Thanks,

 

[jtp10181]

On the Quad unit there is no smoke blown anywhere. Air comes in at the bottom of the stove and as it travels up towards the tubes it gets extremely hot. Then it is injected into the smoke through the tubes which ignites the smoke, secondary combustion.

 

[cmonSTART]

There's a good diagram on this page a ways down.

EDIT: Forgot the URL

(broken link removed to http://www.woodheat.org/technology/woodstoves.htm)

 

[stoveguy2esw]

combustion is achieved when you have 3 factors , fuel, heat, and turbulence of air essentially smoke from the primary fire is trapped briefly, then subjected to heat and oxygen suppplied by a secondary air source. this allows the unburned gasses and particulate matter to be incinerated. this is secondary combustion.

 

[WarmGuy]

OK, I got it. The air coming out the tubes at the top is nothing more than fresh, incoming air, but it's hot because it's traveled along the sides of the firebox. It's so hot that when it collides with the smoke particles and unburned gases it causes them to burn.

Thanks!