@max, Seeing the results of different experiences including mine this could be done. However, don't underestimate the value of heating up the secundary air. In your setup that would be the case much further down the burn.
Hi Peter. I never tried checking with the lighter before. Tho, it seems to draw, at least. Two solutions i envision. Making an iron wall 5mm or so from the firebox endwall, into which thoses hollows under the slants, would feed.
Or making the V out of cast iron?
It was rainy today, so i lit the big rocket stove i made last winter in the workshop. 16 before i lit it. 21 when i left, 3/4 of an hour later. With one load of woodworking offcuts. Pulled the right hand slant before lighting. May be 8mm or so.
Last Edit: Sept 16, 2015 0:45:56 GMT -8 by satamax
Hi! I did such channels, so did Peter, I think. My opinion is that they should have a bigger dimension as the theorical one as they didn't draw as well as the original design maybe because they don't heat so much. Maybe somebody else found different results? Benoit
Last Edit: Aug 24, 2015 11:23:23 GMT -8 by pyrophile
Hmm. Preheating of the secondary air seems to be essential. Last time i had Peter visiting me in Poland... We had great time having some workshops and meeting Larry Winiarski himself. Oh boy... It was super nice.
We had a lot discussion with Peter regarding secondary air... At workshops Peter made a "match-box" (sweet name given by Larry to Peters batch-box) with the one channel placed on the floor directing the air into the riser... The thing was going preety well, although we didn`t made any test...
later more conversation... i asked Peter wheter the secondary channels are actually necessery, since the J-tube burns quite well without them... Peter replied, that actually he was testing his first design without the channels... as i remeber he told me that if the stick will not be touching the front wall of firebox, leaving enough space for air to circulate it should work fine...
mine conclusion as far is like that:
1. if we want to use the secondary air it has to be preheated very well... Sjang idea of the S-port working so well because it preheats the air so well... so we need to find the way of doing it... V shaped cast iron should do the job... i am thing toward the cast iron liner in the firebox, connected with the doors, so the air will be drown through door frame, along the walls of firebox entering to the port from left-right and top...
2. if we do not make a well preheated air (like i did recently repeating the Joris idea), then actually is better to skip it at all, making the build much easier to do.
All of this is just my thought and opinion, which was not tested yet... Now i have few build done, with metal channels, with refractory channel, and without channel as well... once i get my hands on TESTO i will have some confirmation.
Well, a little update. I'm running the stove, to take off the chill. It's a rainy day, about 13c• outside. Started to snow again on the peaks. I've lit the stove with may be a kilo of larch ofcuts. by the time theses were all embers, the bottom v where the air is drawn was drafting nicely I would say. And the firebrick it's made of was warm to the touch. Not 60c• yet, but hotter than skin temp. So now that it's mid way in the first load. It should be hot enough. Hth. Max.
Well, two little videos, one showing the draft with sawdust. The firebox is a smidge smaller than needed, at 900cm² instead of 1007 for a seven incher. And it's not exactly a seven incher, the heat riser being 18cm square tube with rounded corners.
The second one is at startup iirc. Like after lighting the first little fire, and starting to burn bigger pieces, it was pulsating and all. Here you realy can hear the noise.
Lately, it was temperamental, and didn't want to light up fast, it was taking 5 to 15 minutes to start rocketing.
The other day, i had pushed the right slant at the bottom back in. To see if it was doing a difference, from when it was pulled a smidge, to let secondary air come to the port. I didn't notice a straight away difference when i did this, when the stove was hot. So i pulled it back out. Well, actualy, i did this when the stove was hot. And the next day, it started to be temperamental. It's not untill yesterday, that i noticed that the slant had broken in the middle of it's lengh, and the back part was still in contact with the back wall. I obviously pulled it back, may be 1cm, 8mm. And here's the result!
Realy, if you need a secondary air in a botched up build, this is the simplest trick i've discovered soo far.
I've added a neoceram door, well an insert side window. I'm leaning it against the firebox front, with a 1.5cm gap at the bottom. And this has improved things too. I get a gap of around 90cm², when i would need 50 and 13 for primary and secondary. Remember that primary and secondary are taken at the same spot in this case.
If someone asked me if this slanted bottom secondary air works, i'd say yes.
This is a cross between my two systems, the current one, and the future one.
Can you imagine a 18cm square heat riser. With a weird shape uninsulated batch box, and V bottom secondary air. Running a 8.21 ISA all metal double bell?
Here it is!
I'll post the same message in the other post about my new build!
You just can't immagine how chuffed i am. That exceeds previsions. A 7 incher, supposedely could cope with may be 8m² of massonry single bell. Here i'm in double bell mode, with all bare metal arangement.
Madness, i tell you/
About 8m high chimney. And 20x20 sqare with rounded corners.
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deadstarsstillburn: The people over there recommended either a 6" batchbox or an 8" J-tube. I don't know what those are but am going to try to figure that out. What I need is a blueprint that I can scale to fit the need for my house. I have something likne 5000 square feet
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deadstarsstillburn: but I do not need to heat all of it by any means. probably only need to heat half of that, maybe less.
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deadstarsstillburn: moreover, the house has 3 storeys (large attic) so I assume if I get very efficient heating on the ground floor, that will go a long way toward heating the upstairs as well, no?
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dcoyte: I am planning to use a cast iron heat exchanger out of a hydronic boiler set on top of my rocket stove, flue out the top. There will be a pump moving the water through the heat exchanger into an unpressurized 2000 gal tank. Any thoughts?
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