it's the same concept as a rocket stove or the like. Basically the air preheats and when it exits the ports and makes contact with uncombusted solids and fumes within the initial smoke it ignites the smoke itself... at least that's my basic understanding. You can see it pretty clearly in the second photo above, all the air ports around the top edge of the fire pit are blowing flames! It's a pretty neat thing to see for the first time.tinspark wrote: ↑March 17th, 2021, 1:58 pmI have been seeing more of these on other forums too. Mostly as back yard firepits that guys are interested in building. So your saying that the air that circulates between the inner and outer skin will ignite. I am not sure where it gets it's fuel. away from the wood thats on the other side of the metal wall. 3 things are needed to support combustion. 1) heat 2) fuel and 3)oxygen. Take any of those away any the fire is gone. add any of the 3 elements of fire with the support of the other 2 and fire gets bigger. (welding school/safety 101- how to put fires out) Not doubting it because it works somehow, but Still a little confused how the thing actually ignites without solid fuel unless it is somehow igniting gasses (byproduct of unburnt soot/ ignitable gasses??) released from the flame maybe?.. .. Can it be proved out where the fire between the skins actually getting it's fuel source? or will there be a flame shooting out those ports? <maybe Pete /mechanical engineer could explain concept. I have never understood it, But it would be cool!!
Also, would too clean of a fire in a smoker diminish the taste, which is what a smoker is all about ... maybe get rid of all of teh smoke including the blue smoke... IDK?? I think you should build one and test it out !! HAahahah
yeah, my first feeling is it's probably not worth the trouble. but for the sake of science!dacolson wrote: ↑March 17th, 2021, 2:18 pmI’ve seen - and tried - it said that you should have something like 20% of your air intake above the fire to aid in getting a cleaner burn. Did that on my first build. It’s also how all modern wood burning stoves are designed to burn cleaner and use less fuel. Honestly, I’m not sure I see the point in a FB. It’s not that difficult with properly sized vents to get clean smoke as it is. Too clean and - like Tinspark says - you get no smoke on your meat.
Now, that said, I do like me a science and engineering project! If built is good, isn’t over-built better?
Maybe that's why some guys crack their doors. Gets some mixture on top of the fire too? The consensus here is to keep the FB air intakes at or below the bottom of teh coal bed with a raised fire to facilitate combustion.dacolson wrote: ↑March 17th, 2021, 2:18 pmI’ve seen - and tried - it said that you should have something like 20% of your air intake above the fire to aid in getting a cleaner burn. Did that on my first build. It’s also how all modern wood burning stoves are designed to burn cleaner and use less fuel. Honestly, I’m not sure I see the point in a FB. It’s not that difficult with properly sized vents to get clean smoke as it is. Too clean and - like Tinspark says - you get no smoke on your meat.
Now, that said, I do like me a science and engineering project! If built is good, isn’t over-built better?
Yeah, thats teh part I dont understand. It almost looks like it runs like a gas burner, but I am not sure where it is getting the fuel from that inner wall.Kcd2016 wrote: ↑March 17th, 2021, 3:15 pmYou can see it pretty clearly in the second photo above, all the air ports around the top edge of the fire pit are blowing flames! It's a pretty neat thing to see for the first time.tinspark wrote: ↑March 17th, 2021, 1:58 pmI have been seeing more of these on other forums too. Mostly as back yard firepits that guys are interested in building. So your saying that the air that circulates between the inner and outer skin will ignite. I am not sure where it gets it's fuel. away from the wood thats on the other side of the metal wall. 3 things are needed to support combustion. 1) heat 2) fuel and 3)oxygen. Take any of those away any the fire is gone. add any of the 3 elements of fire with the support of the other 2 and fire gets bigger. (welding school/safety 101- how to put fires out) Not doubting it because it works somehow, but Still a little confused how the thing actually ignites without solid fuel unless it is somehow igniting gasses (byproduct of unburnt soot/ ignitable gasses??) released from the flame maybe?.. .. Can it be proved out where the fire between the skins actually getting it's fuel source? or will there be a flame shooting out those ports? <maybe Pete /mechanical engineer could explain concept. I have never understood it, But it would be cool!!
Also, would too clean of a fire in a smoker diminish the taste, which is what a smoker is all about ... maybe get rid of all of teh smoke including the blue smoke... IDK?? I think you should build one and test it out !! HAahahah
You are correct. White or grey smoke contains unburned fuel. At high temp with an injection fo additional air/O2, it recombusts and leaves you with CO2 and water vapor ... or much closer to it.
As long as there’s enough airflow. Should be fine. Wind will always be an issue though. Wind across an opening creates pressure regardless if it’s offset or not. Probably good to have them on either side of the fb still.Kcd2016 wrote:So let's scratch this idea.
What about drawing in at the top of the outside of the firebox and channeling it down before entering the inside of the fb at the bottom? This would avoid wind/weather issues and preheat the air a bit. As long as the channel is large enough would this still present any air flow issues?