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Post by smokeout on Nov 20, 2018 16:07:03 GMT -8
I've been tinkering with my primary air flow. I restricted it as far as I could and still keep the riser lit good. Reducing the air made a huge difference in the heat exchange rate . I'm guessing the slower air through the riser gives the heat exchange more time to extract the heat. Here is a video link youtu.be/1O8nDkjA3T8
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Post by Dan (Upstate NY, USA) on Nov 21, 2018 4:08:17 GMT -8
I think less excess air at 70F while maintaining low CO (meaning there is just enough O2 to keep almost all the exhaust as CO2 instead of CO) is giving you most of your gains...
So yes you have less flow rate which usually DECREASES your heat exchange rate but your exhaust temps are higher because you are not cooling it down too much with 70F primary air...
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Post by drooster on Nov 21, 2018 10:39:08 GMT -8
I've been tinkering with my primary air flow. I restricted it as far as I could and still keep the riser lit good. Reducing the air made a huge difference in the heat exchange rate . I'm guessing the slower air through the riser gives the heat exchange more time to extract the heat. Here is a video link youtu.be/1O8nDkjA3T8Exchange from where to where, and how is it measured? (Not arguing, just want to clarify)
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Post by smokeout on Nov 21, 2018 12:27:09 GMT -8
Hey no problem, I'll be the first to admit my lack of communication skills! When I run my stove full open , I see over 1KF at the top of the heat exchanger and 250-300 F at the bottom of the heat exchanger and around 120 F at the ceiling exit.
When I restricted the primary air as much as I could and still keep my riser temp over 750 F . Anything less than that and my riser starts cooling down. Slowing down the air flow through the stoves gives me a better exchange rate . 750-800 at the top and 150 at the bottom and 108 F existing the ceiling. I'm feeling about the same radiant heat with the lower setting. When I get home I'll try and run tests both ways to establish burn times with both settings. I already know the low setting far exceeds the full open burn time setting. I hope this better explains what I was try to convey.
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Post by drooster on Nov 21, 2018 14:07:02 GMT -8
Well that's good, so you should throttle down your primary air intake every time, but when? If the ideal time doesn't vary you are on to something.
Maybe "exchange rate" is the wrong phrase though... the rate bit is bothering me.
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Post by smokeout on Nov 21, 2018 15:33:37 GMT -8
Maybe exchange efficiency would be better. My thinking is reducing the air flow through the stove allows more time for the gases to cool or exchange the heat through the bell verses if the gas was flowing twice as fast. I'm not sure, but I think my stove would work fine with an even smaller exhaust flue.
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Post by travis on Nov 21, 2018 17:30:45 GMT -8
I feel like I have read a little bit on here about a similar topic. Cant remember where but I think it is important not to throttle it down to early. I tend to think of different stages in the burn. When your wood is just catching and the most violent part of the burn is happening full open is better, then as that tapers off its best to close secondary air completely and adjust primary to the smallest you can Not sure if this is right but the reason might be that having the air flow so high in the later cycle of the fire doesnt tend to add as much heat to your mass. It actually seems to cool it from the inside because the air going in is not hot enough to efficiently give good amounts of heat. An exaggerated example would be leaving the door open after the fire is out fully, this would cool everything so quickly because you continue sending your warmth out the chimney. I think this is the principle you are getting at eh?
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Post by smokeout on Nov 21, 2018 19:09:12 GMT -8
The wood I'm using allows for quick hot startups. Guessing they average about 1"X1" x40" with some being half that size and some being twice that size. One nice feature I incorporated into my stove is an air wash that keeps the horizontal part of the stove from getting hot and it preheats primary and secondary air. I can run the stove at 800-1000 degrees all day and the horizontal portion only reaches 85F. The air wash is on both sides of the burn tunnel. Their dimension is 1"X11", this runs from the very front of the stove almost to the back. It then turns to the inside and comes back to the front of the stove again running parallel to the run going back. I then port into the stove just behind the door.The hot air keeps the glass door nice and clean. I ran the secondary air under the bottom of the horizontal tunnel to the back close to the vertical riser , then the air comes up around both sides and over the top of the horizontal tunnel and then enters the riser at one point. I hope this all makes sense!
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