Quote:
Originally Posted by Steve
By extending the stack higher, the air/heat travels a bit faster thereby drawing more air into the firebox and helping get a better burn. I had to tweek it a bit to find the balance of too fast vs. too slow.
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Right, taller chimney = greater draft. It's a temperature & pressure equation, lower density & pressure inside the chimney due to the heat, higher pressure outside, this causes a natural flow from the firebox and pushes the gas out. I forget the name of the equation offhand though (it's been 20 years since I needed it).
[EDIT: just looked it up, it's called the "Stack Effect" -

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Venturi is when you constrict a flow and the resulting pressure drop on the discharge side of the nozzle. You can pull a line off of that and use that suction to move another fluid, for example, a water eductor pump.
The Ventura effect, well, this is all I got...