Just want to say how much I enjoyed this video and the comprehensive details of the construction of this stove and its parts. Definitely will make one. Love the door. The plug for the mold is what I need more details of as I would say this is going to be my stumbling block. I am 83 years old. I think I would prefer to make the plug in wood. Hope you continue to post more videos on it's progress. Also thanks for the link to the open source info via Peter van den Berg.
Thank you for the kind words Sammy. I hope you enjoy building and can tell you I found it all very satisfying even when things go wrong. Regarding wooden plugs, they will work but my early experiments had some disasters as even quite small defects or slightly bad angles make them difficult to release - my advice would be to use multi-part plugs with at least one section that is not in contact with the casting so it can release reliably and loosen the rest (some sort of wedge arrangement). Foam has the great advantage of being slightly compressible and, if needed, can be cut away. Peter's website is indeed fantastic. I'll post the link again here for any readers not yet familiar with it: batchrocket.eu/ I did eventually install the burner as a mass heater and enjoyed my warmest winter ever. I hope to eventually post a follow-up but have been distracted lately. Thanks again for your comment and good luck! Do let me know if you make progress.
This is great stuff, and an admirably simple design. It's easy to miss the first two videos, since on your channel page they are off-screen to the right. Perhaps you can make a playlist, such that it's easier for those of us new to your content to find and watch your videos in order? Thanks!
Thanks for that tip Hayden, great idea, I'll put a playlist together. I should have thought of doing that as I often find it difficult to navigate other poster's videos when they have a lot of content.
Unless thats a refractory cement, its not going to hold up to the heat very long before the concrete starts to pop, crack, and crumble. Regular concrete can't even hold up to a regular campfire, let alone a fire burning hotter from the air drawn in.
It's refractory, outlined in the other videos. I don't share your experience of regular concrete, I've cast several fire cores with portland cement and easily get a season's service from them. Cracks are not a problem if the design allows for them.
Thanks Kentucky; I'm having fun! I have a burn video with the door in place that should be posted later today or tomorrow, I hope you enjoy that - I did!
Some help for you designing a copper coil or boiler/box heating element for immersion in the flame. The following formula is used to calculate the power of heating element needed to heat a specific volume of water by a given temperature rise in 1 hour. volume in litres x 4 x temperature rise in degrees centigrade / 3412 (4 being a factor and 3412 being a given constant) - for example 200 litres of water, to be heated from 20ºC to 50ºC, giving a temperature rise of 30ºC would give - 200 x 4 x 30 / 3412 = 7.04 meaning that the water would be heated in 4 hours by 1.75kW of applied heat, or in 1 hour by 7.04 KW Thermo-syphoning requires large diameter insulated pipework - preferably 28mm copper, and the pipe run must rise continuously to the hot tank. As this is a stainless boiler you can use it DIRECTLY to heat the water. Just remember that the exit pipe from the boiler should be physically higher than the inlet pipe - even if only a little. Best way to mount this boiler would be on it's side. As long as your system is open vented there is no real chance of an explosion. If you use it indirect you need to either fit an expansion pipe or an expansion vessel in an unvented setup (complicated!). Flow rates not really relevant to a tank system - recycle time more so and that can be calculated as above.
Thanks Dr, that is really useful information. I didn't get much further with developing it as a water heater (but still hope to and will be guided by your data). Thanks.
Can you pleas tell me if the Rams horn flame pattern is the most efficient pattern of flame for complete burning ??? How about a circular pattern ??? Thanks
According to experiments, the circular pattern is too smooth for effective mixing of the gasses. The design of the port forces the ram's horn pattern for maxim turbulent mixing. see here: batchrocket.eu/en/workings
Watching this and the other published videos on your channel, I could not see the construction of the secondary air inlet. Cold you post an image if possible, please?
2:24 if you look at the bottom of the burn chamber, that bit of rectangular steel tube looks like the secondary air inlet. In fact @3:40 you can see he maes sure to keep the fuel away from the end of the tube.
Thanks for the question and sorry for the delay. As TheKlink said, it's just a 2"x1" steel channel set into the floor of the burn chamber casting. It opens at the entrance to the bottom of the heat riser to let air reach the flue gases as they enter and ignite them. In most designs, the channel is shaped to have a vertical piece at the end so that ash and fuel doesn't block it. I always intended to add that as a modification but found the flat version worked fine as long as I didn't pack fuel too deeply and removed excess ash build up. Good luck!
Yes, it looks like it might be better taller. I was using dimensions shown to be efficient from this web site: Batchrocket.eu but suppose they give the minimum efficient height. Thank for the question!
@@batchrocketproject4720 Thanks for the response! I have been planning a large build for a long time now and keep second guessing myself. Hopefully I'll get to it shortly.
@@mothanwrdz I know what you mean about second guessing yourself - I took ages to finally get on it seriously after many half-engaged experiments. I remember shivering one snowy day and decided I wouldn't put it off any longer and began making the foam plug for my casting in doors. Good luck!
Hellow and THANKS! I'm building a bbr4. Your double combustion is amzing, PERFECT! Thanks. I'll warch your other videos to understand the secundary air (p chanell) thrught dwon there. I have it over the fire box. Thanks again 🔥👍!
Yes, the secondary air duct is just the square tube along the floor ending at the base of the riser. I thought it might become blocked with ash but find it stays clear provided fuel isn't crammed too close to the back. The overhead alternative may well be better but I found the floor channel easier to incorporate and it seems to work reliably. Thanks for your comment and good luck with your build.
hoiw many times have you fired the batch stove, has thermal shock caused any cracking of the refractory cement ? Can the burn chamber be made of anything else eg ceramic fibre board ? thanks again
Sorry for the delay in replying. In some of my other videos you will find examples of alarming cracks! But, those were mainly due to the castings being damp from rain and from mechanical shocks. I eventually installed the burner indoors and used it as a mass heater daily for about 5 months - there were no problems with cracks during that time. The castings are fragile but not damaged by heat. I think ceramic fibre boards would work well but, again, may be mechanically weak - no problem if you're gentle when loading fuel. Thanks for the comment.
I have did a test, what is better a normal rocket mass heater with vertikal feed or this? How did you make the rizer, I need a solution for that, is fire concrete a idea?, it needs insolation.
Thanks for your comment and sorry for the delay in responding. My other videos have details of buiding the riser and the materials. I do not now whether the vertical feed versions are better but the advantage of the batch box is that it can be loaded with quite a lot of wood in one go. If you haven't seen it, I can highly recommend Peter van den Berg's website - Batchrocket.eu
tinbender, it may be under a different brand there, although Kerneos, the manufacturer, has a North American office. If you ask at your builder's merchant for high alumina cement, more properly called calcium aluminate cement, they will be able to source something equivalent. I did build some with Portland cement to experiment and they worked fine. Over a few burns the surface of the concrete spalled heavily but the main reason they failed was that they were structurally very weak because of the high perlite content. I think they'd have lasted longer if I'd used clay pebbles too. A compromise would be to experiment with rapid-set cement as these are usually mixtures of Portland and high alumina cement and may have better heat properties, although I haven't tried and don't know how much aluminate is in them. Also, the batchrocket.eu website has lots of designs built with refractory fire brick. It doesn't have to be cast like mine. Thanks for your comment and good luck!
Yes I think that would catch the most heat. The down side is that it might condense more rubbish from the flue gases and cool them. My plan was to instead arrange a copper coil outside the heat riser and enclose all that in a drum. Unfortunately, I've not been able to advance the water-heating experiments yet but hope to one day!
Indeed, invisible particles are probably present. I think the hotter a burn, the less of a problem small particles are (although at a cost of more oxides of nitrogen which are also a problem). In use, the heat riser is enclosed in a 'bell' and is designed for the flue gases to cool to condensation point before exiting the final flue - much of the particulates may be deposited inside the bell along with any condenstate but you're right, nothing is 100% clean.
Great progress, well done. Is this van den Berg chamber more suited to heating hot water than a standard eg 8 inch J tube design ? What is the design of your water heater ? (interested in building an efficient water heater for an off-grid house). I dont know of any rocket stove water boiler heaters that can heat domestic 44 gallon water tank efficiently with no pollution and reduced associated fuel requirement...to me that is very surprising, but they should exist as they are surely highly desirable !! How did you cut the foam to the size of the 3D chamber ? Unsure if copper or stainless steel coil method of heater water in a rocket stove is viable, or maybe direct flame heating a stainless steel tank (like with cooking stoves) will be more effective at heating hot water quicker ?
Hi DRJMF, thanks. My intention is to build a coil that will carry water around the heat riser, inside a bell and circulate from a holding tank. I've considered direct heat into a larger top-tank but believe cool surfaces to be the enemy of a clean burn. Because the flue gasses are hottest as they leave the top of the riser, and cool as they are forced downward towards the base of the bell, the water-carrying pipe should meet hotter gases the hotter the water gets as it siphons up the spiral from the base to the top, rather than meeting cooler gasses as the water heats as would be the case in a simple chimney coil. I hope, but have yet to build prototypes, that this arrangement will allow for a clean burn and efficient thermal siphoning. Because the coil will extract heat 'downwards', it should cause rapid cooling of the flue gasses as they descend the bell and increase draw. I think this is the arrangement used by specialtynotill in the "outback hottie" water heater - th-cam.com/video/wx3HU4yGnFU/w-d-xo.html - although can't be sure as he has few build details. I cut the foam for the mould with a sharp knife and used spray foam and tape to join the pieces. With generous greasings, I was able to reuse the moulds a few times with only minor tape repairs. Thanks for your interest and good luck with your project.
great, use the right stainless steel, copper corrodes and discolours the water. See below url.....they have 32mm tube coil. For heating much quantity of water, they suggest to use 12circles with 32mm SS tube. hope this helps you....I have to say, i want the same as you...hot water and a clean, low fuel burn. Perhaps i can build one and I could vary some parameter different to yours, so we can understand the system better ? I have access to local clay and mix with perlite or sharp sand. www.smartclima.com/stainless-steel-coil-heat-exchanger-for-dutch-tub.htm
Also, unsure if you have researched the clean burn VITA cook stove which was improved upon and scaled up by Instove, www.instove.org/cookstoves. They use 310 grade stainless steel as used in nuclear power plants, can take over 1000 deg C. without thermal oxidation !! 1.5mm sheet is good, but very expensive from Sheffield suppliers. Instove say they can heat 100 litres of water cleanly with minimal Co emission and fuel. Can you estimate the power of their 100 litre capacity burn chamber from this information..... th-cam.com/video/25hdtLgalkc/w-d-xo.html How does the burn chamber size compare to yours, is yours bigger and more powerful at heating water tanks ??? Yours has the advantage that it can be loaded in one go, but J tube rocket stoves are more subtle and need careful dry, thin sticks.....Coal and fan assistance are good ways to increase burn rate/power. I could build a batch rocket out of ceramic insulation board ( Fibrefrax duraboard 25 mm x 1000 mm x 1250 mm 140zk at £111.50 per sheet ) or Vermiculite board (square flue in this material is very instructive) as with 'Dragon heater stoves' in the USA.
I would love to use stainless steel but cost and tools to form it present hurdles for me. The preformed coil in your link looks excellent but I haven't determined the optimum diameter and length for my system yet. I will probably do some experiments with copper and hopefully upgrade to stainless steel when I have a good design. Regarding output, I don't have my estimates to hand but think the burn rate is around 15kW. Of course, I'm unlike to extract all of that even with the most efficient coil but there should be ample output for a tank thermal store which can accumulate hot water over a longer period than the demand cycle. I may later try to build a bigger chamber as the current one could be re-loaded about every 3/4 hour. Although he doesn't use a rocket design, atlantisdiving1 built my favourite water heater I've found on here. It's a water-jacket design with fan controlled burn: th-cam.com/video/_-W87mBw7Go/w-d-xo.html Thanks for the links and ideas. It will be great to compare notes after more progress.
Yes, I think taller risers would cause more draw as with any vertical flue. That said, there are recommended heights depending on the diameter of the flue opening and these will give good efficiency. There is a table here batchrocket.eu/en/building#dimension specifically related to batch burners like this one.
Sorry Im not getting it, I love rocket stoves in general, but as another viewer said what is the point ? Any kind of stove will cease to smoke if the air vent is left open like this, sorry but this is too subtle for me....
Thanks for the comment Gary. This is an early test burn at the start of a possibly long journey to develop a burner with air control which I hope will eventually allow greater control of the burn under limiting primary air, while fully burning the smoke with secondary air in the heat riser. My eventual aim is to build a water heater but that is some way away yet. Do visit again if you're interested. Dave
Hi bobot, sorry for the delay. I've been busy over the summer on other things and still haven't installed the burner yet. I must resume soon though as winter approaches and your comment reminds me of the warm reward possible! thanks for the encouragement.
You could burn the campfire with dry logs and still see no smoke. I was hoping the testburn would be with the burn-chamber door closed with the calculated oxygen inlet. A video made a bit in a hurry and excitement, whitch is ok, but the test should have been more in imitation of the real indoor situation. If there was some darker backround, the video lense made it possible to see the smoke flying around the burnchamber. But still thanks for the video.
Thanks for the comment Tanel. You're right about the circumstances of reporting the experiments. What I was investigating was that the burner behaved as hoped regarding the draw of the heat riser. Because the castings are simply placed together, there are many air gaps that make any meaningful assessment of air entry and burn efficiency impossible. I did eventually install the heater and when all the gaps were sealed, it burned very cleanly and the air control in the door could be used to create a slow burn when the system was fully hot. Incidentally, the 'smoke flying around the burnchamber' is in fact steam coming from the castings which absorbed water from rain. Once hot, the burn is smokeless. Thanks for your comment.
I've not compared placing the secondary air duct above and below but am happy with the lower option and would use it in future. I don't see any advantage to the top version. For me it simplified the casting and met a personal preference that gases move upwards as they warm.
Thanks for the comment rusty and sorry for the delay in replying. Apart from smoke out of the riser at the start of the burn, most of that 'smoke' is steam coming off the damp castings (which were outside and rained on).
Thanks for the comment Ipek, I'll try and answer... Different versions of these types of wood burner can be used for heating and cooking so they do have a practical point. My build, which still has more to do, will eventually, I hope, heat hot water that will go into my domestic radiators to heat my house. It's far from finished. On a more philosophical level, things don't always need a practical point to be interesting. I'm fascinated by the efficient, smokeless burning of wood and would build things like this to experiment even if I had no intention of ever using the heat. Man, or at least men, may even have a built-in fascination with fire, imprinted by survival from before the stone age. I have build many camp fires when I need neither warmth nor food, just to sit and watch the flames; it's as soothing to the soul as watching the sun set or listening to birdsong. You have a fine video of a ghostbuster's car on your channel; we don't have much use for them where I live as ghosts are scarce, but, I'd leap with joy if I saw that fine machine drive down my street! I hope you get it.
I do, I was fascinated by the ram horn pattern. but in the end, I wondered how the heat would be captured. thanks for your reply. great video. keep us updated
The ram's horn flame is very nice to see, but you have to be careful not to burn your face when looking down the heat riser! The pattern is significant because it shows that air is mixing properly with what would otherwise be smoke, and burning it all up. I hope some future videos will show how I capture the heat. I intend to make a coil of copper pipe around the outside of the heat riser and pass water through it. A drum covering the whole thing will force the hot gasses from the burn to travel over the coil where they will heat the water. That's the idea anyway. Thanks for watching and commenting.
Just want to say how much I enjoyed this video and the comprehensive details of the construction of this stove and its parts. Definitely will make one. Love the door. The plug for the mold is what I need more details of as I would say this is going to be my stumbling block. I am 83 years old. I think I would prefer to make the plug in wood. Hope you continue to post more videos on it's progress. Also thanks for the link to the open source info via Peter van den Berg.
Thank you for the kind words Sammy. I hope you enjoy building and can tell you I found it all very satisfying even when things go wrong.
Regarding wooden plugs, they will work but my early experiments had some disasters as even quite small defects or slightly bad angles make them difficult to release - my advice would be to use multi-part plugs with at least one section that is not in contact with the casting so it can release reliably and loosen the rest (some sort of wedge arrangement). Foam has the great advantage of being slightly compressible and, if needed, can be cut away.
Peter's website is indeed fantastic. I'll post the link again here for any readers not yet familiar with it: batchrocket.eu/
I did eventually install the burner as a mass heater and enjoyed my warmest winter ever. I hope to eventually post a follow-up but have been distracted lately.
Thanks again for your comment and good luck! Do let me know if you make progress.
Nice work and no black smoke keep sharing
Thanks for the encouragement Darren. I'm working on the door at present and hope to post another burn when it is fitted.
Fantastic ,you have more than cracked it ,keep well,paul
Thanks Paul. I find those vortices mesmerising, I could watch them all day - if I had a fireproof face! Dave
HAHA same here
You are officially a fire ninja sir. If you don't believe it search fire ninjas only.
True praise! Thanks. After checking google, I love some of those fire ninjas!
This is great stuff, and an admirably simple design.
It's easy to miss the first two videos, since on your channel page they are off-screen to the right. Perhaps you can make a playlist, such that it's easier for those of us new to your content to find and watch your videos in order? Thanks!
Thanks for that tip Hayden, great idea, I'll put a playlist together. I should have thought of doing that as I often find it difficult to navigate other poster's videos when they have a lot of content.
Unless thats a refractory cement, its not going to hold up to the heat very long before the concrete starts to pop, crack, and crumble. Regular concrete can't even hold up to a regular campfire, let alone a fire burning hotter from the air drawn in.
It's refractory, outlined in the other videos. I don't share your experience of regular concrete, I've cast several fire cores with portland cement and easily get a season's service from them. Cracks are not a problem if the design allows for them.
Impressive performance!
Thanks Kentucky; I'm having fun! I have a burn video with the door in place that should be posted later today or tomorrow, I hope you enjoy that - I did!
Some help for you designing a copper coil or boiler/box heating element for immersion in the flame. The following formula is used to calculate the power of heating element needed to heat a specific volume of water by a given temperature rise in 1 hour.
volume in litres x 4 x temperature rise in degrees centigrade / 3412
(4 being a factor and 3412 being a given constant) - for example 200 litres of water, to be heated from 20ºC to 50ºC, giving a temperature rise of 30ºC would give -
200 x 4 x 30 / 3412 = 7.04
meaning that the water would be heated in 4 hours by 1.75kW of applied heat, or in 1 hour by 7.04 KW
Thermo-syphoning requires large diameter insulated pipework - preferably 28mm copper, and the pipe run must rise continuously to the hot tank. As this is a stainless boiler you can use it DIRECTLY to heat the water. Just remember that the exit pipe from the boiler should be physically higher than the inlet pipe - even if only a little. Best way to mount this boiler would be on it's side. As long as your system is open vented there is no real chance of an explosion. If you use it indirect you need to either fit an expansion pipe or an expansion vessel in an unvented setup (complicated!). Flow rates not really relevant to a tank system - recycle time more so and that can be calculated as above.
Thanks Dr, that is really useful information. I didn't get much further with developing it as a water heater (but still hope to and will be guided by your data). Thanks.
De q material está hecho? Me llama la.atencion.q no explota si fuera hormigón o algún derivado de cemento. Aguardó alguna respuesta en castellano
vea otros videos para materiales y métodos. Gracias por tu comentario.
Can you pleas tell me if the Rams horn flame pattern is the most efficient pattern of flame for complete burning ??? How about a circular pattern ??? Thanks
Good question - but I don't know the answer. I suspect that any turbulence will increase the mixing of flue gasses with air and cause a cleaner burn.
According to experiments, the circular pattern is too smooth for effective mixing of the gasses. The design of the port forces the ram's horn pattern for maxim turbulent mixing.
see here: batchrocket.eu/en/workings
@@codetech5598 Thanks, I'd forgotten how detailed the stuff on batchrocket.eu is.
Watching this and the other published videos on your channel, I could not see the construction of the secondary air inlet. Cold you post an image if possible, please?
2:24 if you look at the bottom of the burn chamber, that bit of rectangular steel tube looks like the secondary air inlet.
In fact @3:40 you can see he maes sure to keep the fuel away from the end of the tube.
Thanks for the question and sorry for the delay. As TheKlink said, it's just a 2"x1" steel channel set into the floor of the burn chamber casting. It opens at the entrance to the bottom of the heat riser to let air reach the flue gases as they enter and ignite them. In most designs, the channel is shaped to have a vertical piece at the end so that ash and fuel doesn't block it. I always intended to add that as a modification but found the flat version worked fine as long as I didn't pack fuel too deeply and removed excess ash build up.
Good luck!
Thanks.
Why not make a taller heat riser if the flames are reaching the top? Would that not increase combustion efficiency and heat generation?
Yes, it looks like it might be better taller. I was using dimensions shown to be efficient from this web site: Batchrocket.eu but suppose they give the minimum efficient height. Thank for the question!
@@batchrocketproject4720 Thanks for the response! I have been planning a large build for a long time now and keep second guessing myself. Hopefully I'll get to it shortly.
@@mothanwrdz I know what you mean about second guessing yourself - I took ages to finally get on it seriously after many half-engaged experiments. I remember shivering one snowy day and decided I wouldn't put it off any longer and began making the foam plug for my casting in doors.
Good luck!
Hellow and THANKS! I'm building a bbr4. Your double combustion is amzing, PERFECT! Thanks.
I'll warch your other videos to understand the secundary air (p chanell) thrught dwon there. I have it over the fire box. Thanks again 🔥👍!
Yes, the secondary air duct is just the square tube along the floor ending at the base of the riser. I thought it might become blocked with ash but find it stays clear provided fuel isn't crammed too close to the back. The overhead alternative may well be better but I found the floor channel easier to incorporate and it seems to work reliably. Thanks for your comment and good luck with your build.
hoiw many times have you fired the batch stove, has thermal shock caused any cracking of the refractory cement ? Can the burn chamber be made of anything else eg ceramic fibre board ? thanks again
Sorry for the delay in replying.
In some of my other videos you will find examples of alarming cracks! But, those were mainly due to the castings being damp from rain and from mechanical shocks. I eventually installed the burner indoors and used it as a mass heater daily for about 5 months - there were no problems with cracks during that time. The castings are fragile but not damaged by heat.
I think ceramic fibre boards would work well but, again, may be mechanically weak - no problem if you're gentle when loading fuel.
Thanks for the comment.
I have did a test, what is better a normal rocket mass heater with vertikal feed or this? How did you make the rizer, I need a solution for that, is fire concrete a idea?, it needs insolation.
Thanks for your comment and sorry for the delay in responding. My other videos have details of buiding the riser and the materials. I do not now whether the vertical feed versions are better but the advantage of the batch box is that it can be loaded with quite a lot of wood in one go. If you haven't seen it, I can highly recommend Peter van den Berg's website -
Batchrocket.eu
thats pretty cool but i dont know where to find ciment fondu in washington state, US
tinbender, it may be under a different brand there, although Kerneos, the manufacturer, has a North American office. If you ask at your builder's merchant for high alumina cement, more properly called calcium aluminate cement, they will be able to source something equivalent.
I did build some with Portland cement to experiment and they worked fine. Over a few burns the surface of the concrete spalled heavily but the main reason they failed was that they were structurally very weak because of the high perlite content. I think they'd have lasted longer if I'd used clay pebbles too.
A compromise would be to experiment with rapid-set cement as these are usually mixtures of Portland and high alumina cement and may have better heat properties, although I haven't tried and don't know how much aluminate is in them.
Also, the batchrocket.eu website has lots of designs built with refractory fire brick. It doesn't have to be cast like mine.
Thanks for your comment and good luck!
What about putting a water boiler (steel) on top and enclosing the whole thing?
Yes I think that would catch the most heat. The down side is that it might condense more rubbish from the flue gases and cool them. My plan was to instead arrange a copper coil outside the heat riser and enclose all that in a drum.
Unfortunately, I've not been able to advance the water-heating experiments yet but hope to one day!
Enough fine particles present? these need to be tackled in future, a electrostat for example.
Indeed, invisible particles are probably present. I think the hotter a burn, the less of a problem small particles are (although at a cost of more oxides of nitrogen which are also a problem). In use, the heat riser is enclosed in a 'bell' and is designed for the flue gases to cool to condensation point before exiting the final flue - much of the particulates may be deposited inside the bell along with any condenstate but you're right, nothing is 100% clean.
Great progress, well done. Is this van den Berg chamber more suited to heating hot water than a standard eg 8 inch J tube design ? What is the design of your water heater ? (interested in building an efficient water heater for an off-grid house). I dont know of any rocket stove water boiler heaters that can heat domestic 44 gallon water tank efficiently with no pollution and reduced associated fuel requirement...to me that is very surprising, but they should exist as they are surely highly desirable !! How did you cut the foam to the size of the 3D chamber ? Unsure if copper or stainless steel coil method of heater water in a rocket stove is viable, or maybe direct flame heating a stainless steel tank (like with cooking stoves) will be more effective at heating hot water quicker ?
Hi DRJMF, thanks. My intention is to build a coil that will carry water around the heat riser, inside a bell and circulate from a holding tank. I've considered direct heat into a larger top-tank but believe cool surfaces to be the enemy of a clean burn. Because the flue gasses are hottest as they leave the top of the riser, and cool as they are forced downward towards the base of the bell, the water-carrying pipe should meet hotter gases the hotter the water gets as it siphons up the spiral from the base to the top, rather than meeting cooler gasses as the water heats as would be the case in a simple chimney coil.
I hope, but have yet to build prototypes, that this arrangement will allow for a clean burn and efficient thermal siphoning. Because the coil will extract heat 'downwards', it should cause rapid cooling of the flue gasses as they descend the bell and increase draw. I think this is the arrangement used by specialtynotill in the "outback hottie" water heater - th-cam.com/video/wx3HU4yGnFU/w-d-xo.html - although can't be sure as he has few build details.
I cut the foam for the mould with a sharp knife and used spray foam and tape to join the pieces. With generous greasings, I was able to reuse the moulds a few times with only minor tape repairs.
Thanks for your interest and good luck with your project.
great, use the right stainless steel, copper corrodes and discolours the water. See below url.....they have 32mm tube coil. For heating much quantity of water, they suggest to use 12circles with 32mm SS tube. hope this helps you....I have to say, i want the same as you...hot water and a clean, low fuel burn. Perhaps i can build one and I could vary some parameter different to yours, so we can understand the system better ? I have access to local clay and mix with perlite or sharp sand.
www.smartclima.com/stainless-steel-coil-heat-exchanger-for-dutch-tub.htm
Also, unsure if you have researched the clean burn VITA cook stove which was improved upon and scaled up by Instove, www.instove.org/cookstoves.
They use 310 grade stainless steel as used in nuclear power plants, can take over 1000 deg C. without thermal oxidation !! 1.5mm sheet is good, but very expensive from Sheffield suppliers.
Instove say they can heat 100 litres of water cleanly with minimal Co emission and fuel. Can you estimate the power of their 100 litre capacity burn chamber from this information.....
th-cam.com/video/25hdtLgalkc/w-d-xo.html
How does the burn chamber size compare to yours, is yours bigger and more powerful at heating water tanks ??? Yours has the advantage that it can be loaded in one go, but J tube rocket stoves are more subtle and need careful dry, thin sticks.....Coal and fan assistance are good ways to increase burn rate/power. I could build a batch rocket out of ceramic insulation board ( Fibrefrax duraboard 25 mm x 1000 mm x 1250 mm 140zk at £111.50 per sheet ) or Vermiculite board (square flue in this material is very instructive) as with 'Dragon heater stoves' in the USA.
I would love to use stainless steel but cost and tools to form it present hurdles for me. The preformed coil in your link looks excellent but I haven't determined the optimum diameter and length for my system yet. I will probably do some experiments with copper and hopefully upgrade to stainless steel when I have a good design.
Regarding output, I don't have my estimates to hand but think the burn rate is around 15kW. Of course, I'm unlike to extract all of that even with the most efficient coil but there should be ample output for a tank thermal store which can accumulate hot water over a longer period than the demand cycle. I may later try to build a bigger chamber as the current one could be re-loaded about every 3/4 hour.
Although he doesn't use a rocket design, atlantisdiving1 built my favourite water heater I've found on here. It's a water-jacket design with fan controlled burn: th-cam.com/video/_-W87mBw7Go/w-d-xo.html
Thanks for the links and ideas. It will be great to compare notes after more progress.
By the way is it better to have a high riser or a short riser, Thanks
The taller the more rockety
Yes, I think taller risers would cause more draw as with any vertical flue. That said, there are recommended heights depending on the diameter of the flue opening and these will give good efficiency. There is a table here batchrocket.eu/en/building#dimension specifically related to batch burners like this one.
You can put a gas stove grate on top and cook something with heat like that. :)
Sorry Im not getting it, I love rocket stoves in general, but as another viewer said what is the point ?
Any kind of stove will cease to smoke if the air vent is left open like this, sorry but this is too subtle for me....
Thanks for the comment Gary. This is an early test burn at the start of a possibly long journey to develop a burner with air control which I hope will eventually allow greater control of the burn under limiting primary air, while fully burning the smoke with secondary air in the heat riser. My eventual aim is to build a water heater but that is some way away yet. Do visit again if you're interested. Dave
Awesome job i subscribed these are some of the best most helpful videos ive seen for this style stove. Good job. Keep it up!
modifiedchevy - thanks for your kind comment, most encouraging.
As of now maybe you already installed the stove inside the house
And I bet it changed everything like it happened to me. Good Luck
God Bless
Hi bobot, sorry for the delay. I've been busy over the summer on other things and still haven't installed the burner yet. I must resume soon though as winter approaches and your comment reminds me of the warm reward possible! thanks for the encouragement.
You could burn the campfire with dry logs and still see no smoke. I was hoping the testburn would be with the burn-chamber door closed with the calculated oxygen inlet. A video made a bit in a hurry and excitement, whitch is ok, but the test should have been more in imitation of the real indoor situation. If there was some darker backround, the video lense made it possible to see the smoke flying around the burnchamber. But still thanks for the video.
Thanks for the comment Tanel. You're right about the circumstances of reporting the experiments. What I was investigating was that the burner behaved as hoped regarding the draw of the heat riser. Because the castings are simply placed together, there are many air gaps that make any meaningful assessment of air entry and burn efficiency impossible. I did eventually install the heater and when all the gaps were sealed, it burned very cleanly and the air control in the door could be used to create a slow burn when the system was fully hot.
Incidentally, the 'smoke flying around the burnchamber' is in fact steam coming from the castings which absorbed water from rain. Once hot, the burn is smokeless.
Thanks for your comment.
Don't you think it would be better to pass the tube above the flames?
I've not compared placing the secondary air duct above and below but am happy with the lower option and would use it in future. I don't see any advantage to the top version. For me it simplified the casting and met a personal preference that gases move upwards as they warm.
Looks like smoke coming from the bottom of the heat riser
Thanks for the comment rusty and sorry for the delay in replying. Apart from smoke out of the riser at the start of the burn, most of that 'smoke' is steam coming off the damp castings (which were outside and rained on).
Интересно
what's the point? You cant heat wiith this nor can you cook...
Thanks for the comment Ipek, I'll try and answer...
Different versions of these types of wood burner can be used for heating and cooking so they do have a practical point. My build, which still has more to do, will eventually, I hope, heat hot water that will go into my domestic radiators to heat my house. It's far from finished.
On a more philosophical level, things don't always need a practical point to be interesting. I'm fascinated by the efficient, smokeless burning of wood and would build things like this to experiment even if I had no intention of ever using the heat. Man, or at least men, may even have a built-in fascination with fire, imprinted by survival from before the stone age. I have build many camp fires when I need neither warmth nor food, just to sit and watch the flames; it's as soothing to the soul as watching the sun set or listening to birdsong. You have a fine video of a ghostbuster's car on your channel; we don't have much use for them where I live as ghosts are scarce, but, I'd leap with joy if I saw that fine machine drive down my street! I hope you get it.
I do, I was fascinated by the ram horn pattern. but in the end, I wondered how the heat would be captured. thanks for your reply. great video. keep us updated
The ram's horn flame is very nice to see, but you have to be careful not to burn your face when looking down the heat riser! The pattern is significant because it shows that air is mixing properly with what would otherwise be smoke, and burning it all up.
I hope some future videos will show how I capture the heat. I intend to make a coil of copper pipe around the outside of the heat riser and pass water through it. A drum covering the whole thing will force the hot gasses from the burn to travel over the coil where they will heat the water. That's the idea anyway.
Thanks for watching and commenting.