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Post by patamos on Jun 13, 2015 8:59:50 GMT -8
I'm in,
Will be building the batch box with splits ala Matt's configuration.
I have two 18" tall x 6" round sections of heat riser already laying around. I could leave them at that height to see what the added dome offers (?) Perhaps cut taller and narrower throats (?) Perhaps shape in some trip wires in the second port between the half risers…
Maybe taller risers will give the system a little more push… but at what cost… ?
Adiel, regarding your comment:
"2 - secondarry air is two channels (12 % together) that give to the second port one from above and one from below."
I am a bit confused by this. Is there still 12% of CSA secondary air coming through the bottom front of the fire box towards the bottom back port ala Matt's configuration? Or half of that from above ala Peter's channel? And by 'second port' do you mean the port between the two half risers? If so how is the air being delivered to the second port? Or is there a second set of channels from the front of the stove, parallel to the ones in the door?
Apologies if i missed something obvious earlier on.
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adiel
Junior Member
Posts: 119
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Post by adiel on Jun 16, 2015 8:27:59 GMT -8
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Post by patamos on Jun 16, 2015 14:05:33 GMT -8
Beautiful
It looks like you shortened the second port rather than narrowed it (?)
Perhaps the smoke back offers a good rational for involving a bypass?
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adiel
Junior Member
Posts: 119
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Post by adiel on Jun 17, 2015 0:27:38 GMT -8
Beautiful It looks like you shortened the second port rather than narrowed it (?) Perhaps the smoke back offers a good rational for involving a bypass? No - i narrowed it. There is a bypass. And still... |
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Post by peterberg on Jun 17, 2015 6:30:07 GMT -8
Very interesting! During 2012 I've found the same sort of effects. Smokeback is more likely when the port is less than 70% but performance is better. Also, the overall stability of the system during more runs turned out to be less. Especially when the draw of the chimney was lower, there are some fluctuations now and then. So at the time, the 70% port size turned out to yield the best averages overall.
It's clear that this riser-less core isn't any different. Being a race horce, speedy but nervous.
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Post by patamos on Jun 17, 2015 6:41:19 GMT -8
Assuming Matt's test numbers with his square risers model were accurate enough (despite excess O2) to imply that he had no smoke coming out the chimney…
perhaps the square risers had the effect of slowing the horse down but still evoking enough flow through the ports to minimize stalling?
I wonder what a round first riser (capacitor?) and square second one with a larger port size between them would offer?
Unfortunately for now my desire to experiment is far greater than my time to do it
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Post by shilo on Jun 17, 2015 8:46:43 GMT -8
Very interesting! During 2012 I've found the same sort of effects. Smokeback is more likely when the port is less than 70% but performance is better. Also, the overall stability of the system during more runs turned out to be less. Especially when the draw of the chimney was lower, there are some fluctuations now and then. So at the time, the 70% port size turned out to yield the best averages overall. It's clear that this riser-less core isn't any different. Being a race horce, speedy but nervous. but in the original box wood bloc part of the port (larger part in the case of side box) in this new case it always 100% open. that was the reason I thought we should narrow it.
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Post by satamax on Jun 17, 2015 9:07:29 GMT -8
Very interesting! During 2012 I've found the same sort of effects. Smokeback is more likely when the port is less than 70% but performance is better. Peter, that makes me think about my range retrofit. The firebox and port being around right measurements for a 10cm riser, while the heat riser itself is 12cm. It seemed to roar madly every time i used it. |
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adiel
Junior Member
Posts: 119
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Post by adiel on Jun 17, 2015 9:48:10 GMT -8
Very interesting! During 2012 I've found the same sort of effects. Smokeback is more likely when the port is less than 70% but performance is better. Peter, that makes me think about my range retrofit. The firebox and port being around right measurements for a 10cm riser, while the heat riser itself is 12cm. It seemed to roar madly every time i used it. my 5" in the workshop was working during the winter and had the same thing - smaller then 70% port. but! - i saw an amazing change when i added another seconderry -6% - from the bottom so there where two channels next to the port - one from above and one from undernith. it did all the best i could wish for - no smoke and no smokebacks. and i'm doing it every time now. |
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Post by peterberg on Jun 17, 2015 11:46:12 GMT -8
You could be right Adiel, I didn't try the floor channel at the time because the idea didn't show up. But both the s-portal and Matt's pre-port tube are adding more air to the port where that wasn't before. The simplicity of that floor channel is very tempting, I already planned to use that in my new home heater although that will be a straight version.
Shilo, that's a completely new insight and you are right. The port to the actual riser in Matt's core is always wide open, unlike the straight version.
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Post by pyrophile on Jun 18, 2015 13:08:24 GMT -8
Hi all!
Well, I am not sure I understand everything (my english combined with an old computer which refuses many images...) !
Would it be possible to see a drawing of this new design to help me to understand?
Thanks a lot!
Benoit
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cheez
New Member
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Post by cheez on Mar 3, 2016 16:10:42 GMT -8
Hi there, I came across this design a few weeks ago, and have been trying to use it to heat a bench in my plastic greenhouse. I was interested due to the design's compact footprint and its lack of a large radiant heat source (since the greenhouse is plastic). However I have not been able to run it successfully without significant smokeback. The first port (the transition from the box to the "capacitator") seems to be the bulk of the issue. Only a portion of the flames are actually pulled in, while the rest rise towards the roof of the firebox, and come back out the front. I have tried widening the first port from 2-4inches, and I have tried making it taller, even to the point of removing the "capacitator", but with no luck. Today I had some time to try again so I experimented with adjusting the cross section of the upper portion of the burn tunnel (above the box), but it did not significantly alter the performance... hey all we had a very good try with matt's core. after tallking with peter we made 2 changes 1 - first port is almost csa (226 cm sq) and second one is about 75% 2 - secondarry air is two channels (12 % together) that give to the second port one from above and one from below. Adiel am I to understand that in your final configuration you made the first port equal to the size of the heat riser csa? With standard firebricks the riser comes out to about 7 sq.in. so if I were to make the first port that big there wouldn't be an overhang between the "capacitator" and the firebox. I'm also confused by the second port. In the picture on the walker stove website, it looks to be about 2inches wide x 9inches tall x 6inches deep. The width and height line up relatively close to the batch box calculator, but the depth in the picture and in my build is 3 times the calculator. Adiel when you say you made the second port 75%csa, what did you make the depth?  When viewing the fire from the top of the burn tunnel I'm definitely seeing the flames pass through the first and second port, and start to form the "ram's horn" inside the burn tunnel, but there is still a fair amount of fire, smoke, and heat being exhausted out the front of the stove. One thing I just now considered is that since I don't have any ceramic glass or steel on hand, I built the top of the core out of firebricks as well, they're well sealed with mortar, but could they be retaining too much heat and diminishing the draft? I can't think of any other tweaks to make currently... |
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Post by satamax on Mar 3, 2016 22:11:58 GMT -8
Cheez, what is your chimney?
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Post by Vortex on Mar 4, 2016 1:57:10 GMT -8
And what are you using as a door?
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cheez
New Member
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Post by cheez on Mar 4, 2016 7:53:05 GMT -8
Satamax:
I've tried two different chimneys. For the first one I actually hooked it into the system I was hoping to heat. Which is about a 12ft horizontal run of chimney pipe through the middle of two short cinderblock walls. (the plan was eventually to fill that space with some kind of mass, rocks, dirt, maybe even cob when it gets warmer, etc.) At the end there's a tee where I primed the chimney and a 10ft piece of vertical chimney pipe tied into the tee. There was a little steam coming out at the far end, really lazy-looking. I figured it might not be drafting enough, so I redid the chimney with just a short horizontal 8ft piece of pipe coming almost directly out of the core, and then I took some of the chimney pipe and made about a 16ft vertical stack. That definitely drafted better, with little to no visible smoke after a few minutes, but I think that's mostly because there's still a good bit of smoke coming back into the greenhouse.
Vortex:
for a door I'm just using a thin sheet of steel with a flange around the outside so that it fits into the door (it's a baking sheet actually). It's not air tight by any means, but i was under the impression that the core would still run even if it weren't totally sealed. Obviously if i had a good seal, I wouldn't have a problem with smokeback except for when I opened and closed the door since the smoke couldn't come out during normal operation. I didn't want to go through the effort of actually making a door for it until I knew it worked, and from the videos I saw it seemed like success was being had with just a piece of ceramic glass leaning against the door.
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