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 rocket stove project and problems

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giggo



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Join date : 2014-12-24

PostSubject: rocket stove project and problems   Wed Dec 31, 2014 12:07 pm







So after many trial and errors, this is the version 4 :)

The problem I'am having with the RS is the second combustion. Its like the temp in the riser is on the border for the second combustion and in the start of fire, it looks promising and theres no smoke coming from riser, but as time is passing it seems like its harder to maintain the second combustion and the temp at the top of the riser starts to go down.
We put the second air intake directly into the bottom of the riser and there wasnt a lot of difference in performance.....and that pretty much where we lost ideas.... scratch scratch

is it the dimensions that we got wrong, the air intake is not good enough?......any advice and ideas would be very welcomed study
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ROACH

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PostSubject: rocket stove projet and problems   Wed Dec 31, 2014 1:42 pm

looks like your secondary air need to reposition inside of burn tube and also need to put rockwool on the stack to keep temps higher also is your burn tube getting full of ash
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caotropheus
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PostSubject: Re: rocket stove project and problems   Wed Dec 31, 2014 2:19 pm

Secondary combustion occurs when temperatures reach close to 300ºC. Also secondary combustion occurs while wood release wood gas, and that happens only during the first half or 2/3 of the combustion, before wood turns into charcoal. What is the dimension of the holes for the secondary combustion, at the base of the riser tube? can you please show us a picture on the inside of the horizontal tube? What sort of components did you insert there inside? Can you show us details of these components? I would suggest to put some controls for the primary air and to insulate the horizontal tube and base of the riser tube, where combustion occurs. Light the stove, play with primary air controls and see what happens.
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giggo



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Join date : 2014-12-24

PostSubject: Re: rocket stove project and problems   Wed Dec 31, 2014 3:03 pm

i wanted to show the inside, but its pretty hard to see anything...thats why i put the sketch picture.

the components inside are 2 layers of fire brick(the yellow on the sketch) and just those iron ribs that ash falls throu. thats why i put the correct dimensions of everything so you can see how things inside looks. if you cut the RS throu middle thats how it would look Very Happy

hole for the air intake at the riser tube is cca 55x55mm. idk if i saw it on this forum or on YT, but someone done that secondary air intake with steel pipe throu the inside of the burn chamber to the bottom of riser so the air coming in is already warm....was planning to try out that....

and also vortex looks like a pretty good idea to put also, its generates more heat and thats something i have problem with...

but true to be told....when i was testing i didnt put the fire brick insulation on the riser (like one of the pic has it) and it might made the riser to lose heat.

as for the ash in the burn chamber, yeah actually there is more then i thought it would be
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gadily
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PostSubject: Re: rocket stove project and problems   Wed Dec 31, 2014 9:20 pm

the videos ive caught





from my reading you have a 9 3/4" sq tube with 2 layers of firebrick, proper firebrick is 2 1/2" but you can get 1" thick firebrick
a 2" secondary air tube

what is your exact size of burn chamber as from my reading the burn chamber is about 4 1/2" or less depending on your size of ash box

? with ash is it filling up your burn chamber on that tube

and secondary air is much better using 1" x 1" i used 1 1/2" round but i placed it inside of the burn chamber as it keeps the tube much hotter the internal dimensions or the round gave me 1 1/4" for secondary air input

i would like to mention that these most vids on youtube are not tried and tested over a long period of usage
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gadily
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PostSubject: Re: rocket stove project and problems   Thu Jan 01, 2015 12:11 am

also what we are finding out heres the problem with just using steel



2 years with ss

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giggo



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Join date : 2014-12-24

PostSubject: Re: rocket stove project and problems   Wed Jan 14, 2015 4:50 pm

Ok, holidays are over....back to fixing the problems :)

after following ppotty1's new stove project in December (too bad he didnt start it earlier, would be much less rewelding and recutting  Very Happy ) we decided to modify our stove to his ideas cuz I must say that RS ended up looking pretty awesome and working super efficient. And since we were already going with the square look, it didnt need a lot of modifiying. Heres how it looks atm





we had to built the vortex with fire bricks in various shapes, but i think it turned out pretty good. second airtake hole as suggested in the videos, at the end of the tunnel just before the riser. But we didnt go with the pipe tip going inside the chamber, but drilled a hole in fire brick at the angle. So basically the pipe goes 90 deg to the brick and then hole in the brick is with an angle so that it goes more along the air flow from the firebox.

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gadily
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PostSubject: Re: rocket stove project and problems   Wed Jan 14, 2015 10:39 pm

it looks really good as well

i think thats best with the secondary air inline with the flow however in some cases the flow needs to be mixed better so which is better to use either inline or at an angle into the flow of the gas burning off

also id probably chop the round off and make a round vortex tube using the perlite and cement mix to create the tube but you can do that later if you want to get it up and running asap

after build you can then understand how it works and then make your own contribution on another build much better to use someones tried and tested method first then go from there and make your own design after that
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giggo



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PostSubject: Re: rocket stove project and problems   Thu Jan 15, 2015 2:28 am

yeah we will for sure build one more...this one will go for the greenhouse and my dad wants to make one more for his workshop. and on that version we will go without steel riser tube, but this version already had steel riser pipe in use so we went with it so its not wasted now after all changes.

but on next version we already agreed its gonna be some fire resistant material, it proved to be cheaper and more durable in the long run.
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gadily
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PostSubject: Re: rocket stove project and problems   Thu Jan 15, 2015 2:50 am

if your using steel for your riser it wont last long a few months at best as under advisement if you want to continue just get ready to replace the vortex tube

within this link is 2mm steel vortex


yours looks about 5mm

2 years with stainless steel vortex tube could be longer if yours is not jointed tube
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giggo



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Join date : 2014-12-24

PostSubject: Re: rocket stove project and problems   Tue Jan 27, 2015 11:23 am

and all the modifications are done....I hope so.....cuz after first burn we need to look inside if everything is working as intended. we noticed slight problem with the primary air intake cuz preheated air, well is not heating fast enough due to slower heating of the primary air tube. i guess when you are doing upgrade on the upgrade of the upgrade, you lack space for bigger modifications so will try to find some solution to preheat the primary air a little faster, cuz there was a lot of smoke from backdraft before whole thing became really hot, then it worked really good....

firebricks inside burn chamber


insulated with firebricks around second chamber and riser, second air intake, little handle for regulating 90deg movement of metal plate inside the primary air intake


problematic primary air take at the bottom for which we need to find some easy to implement option to fix it


full assembly I nicknamed INFERNO.....:)
and yeah, we closed everything then noticed that we forgot to put one more firebrick pipe on the bottom of riser with wider radius....    
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Lizard



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PostSubject: Re: rocket stove project and problems   Tue Jan 27, 2015 11:53 am

Nice build!!
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twistedkarma

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PostSubject: Re: rocket stove project and problems   Tue Jan 27, 2015 9:45 pm

how hot is your chimney pipe exit? under running load.
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gadily
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PostSubject: Re: rocket stove project and problems   Tue Jan 27, 2015 10:19 pm

nice build there giggo

with backdraft issues ive found that out myself though i used 4 3/4" for my second burn tube however i beat that by changing the way i light the fire on start up of the system it can be trail and error until you find the right way but a few papers inside of secondary burn tube and a few sticks on top then light it and get it going the tube vortex does pull well better than the square this aids on the start up of the system

ive got to ask how much of ppottys burn box did you copy and did you use the internal slats of steel as well if you did thats fine

how long of a first burn did you run in it

another question ppotty used 1" firebrick for the base and metal underneath total i reckon is about 3cm or 30mm in thickness or less if used 3mm steel not 6mm is yours any thicker

that primary air inlet underneath is it 50mm x 100mm as this can be widened and thinned down or if you insert a sloped steel to half its thickness will create the air to heat up even more the closer it gets to the burn chamber above
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giggo



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PostSubject: Re: rocket stove project and problems   Wed Jan 28, 2015 7:42 am

twistedkarma wrote:
how hot is your chimney pipe exit?  under running load.

its around 60C i would say....can touch it, but cant hold hand on it.

----------------------

today we did a second burn. it went much better with very little smoke escaping the chamber. we used the method you said with lighting up inside the second chamber, plus we solve the backdraft on the primary air inlet with a simple solution....bathroom heater blowing hot air inside inlet for 10mins, it speed up things a lot Very Happy

one of problem for lots of smoke in the start might be the choice of wood we are using - black locust. Last summer when we were clearing the place for greenhouse there was a lots of wild black locust we cut down. Its quality firewood, but it has a slow burn and not really good for starting fire and rapid heating, more for the later when system is already hot. Plus, it didnt had time to really dry fully also....

as for ppottys burn box, yeah we tried to copy it as close as possible, but due to upgrading limits there are some dimension difference. But yes we did made the internal slats on sides of the firebox in zigzag formation so the air catches more heat.

the first burn was about 3 hours, then we put the last woods and let it go overnight. It was only ash left in the morning. Thermal paint that we used had to burn off also, stinky as hell....but today on second burn it was fine with the paint.

the bottom we had to use 2" firebrick plus metal underneath, so yeah its almost twice thicker than ppottys, which does impact the heating of the primary air, takes a while for heat to reach the surface of the primary air inlet, which is i think 50mm x 200mm. I believe it is big enough, its simply the situation that its on the bottom, where is cold and heat from above takes time before heating the inlet.....the heater blowing hot air was just an experiment which worked, but we will have to try to make up some better solution...
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gadily
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PostSubject: Re: rocket stove project and problems   Wed Jan 28, 2015 8:29 am

use as close to pine as possible as that is quick heat and burns fast then after 1 load of pine use the black locust for long burns in your system

pine wood will bring it up to temp much faster

60c is around most chimney temps

i believe ppotty uses just normal paper screwed up to start his system but ive tried a few times with mine and i find a little fire inside of second burn chamber helps to get them going with very little back draft of smoke from the system

also best if wood not dry is to dry it out near the system

giggo ?

do you mean your secondary air to vortex tube or do you mean your primary air on your firebox your having issues with the back draft

i dont know if you have got a long chimney say above 1 storey as ppottys is it does make a difference when its connected to a chimney

if its at your primary air in the firebox do as suggested then build it out into the firebox but keep it low until that system is pulling well up the vortex tube at this point you can then fill the fire box to full

its something i found out while fireing mine up and using a bigger firebox
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