I definitely want to take a welding class now. I can't wait to get my son to watch this. Now, he's a welder. Thank you for taking the time to share your knowledge. God bless you.
ppotty1, Thanks so much for this video series. I've been researching 'rocket' style heaters for over 3 years, and this series has been by far the best first-hand information I have come across about (non-mass storage) heater design and testing. I'm beginning the design and build of a heater for my house, a bit smaller than the size of yours and I plan to use many of the features you've improved upon with this model. One of the major differences in my design will be the predominant use of homemade refractory materials over steel (wherever possible), in order to reduce the cost of the build. Before you mentioned an 'easier way to preheat the combustion air' in this video, I was thinking the exact same thing - you have much higher temperatures available within the heat exchanger volumes than you have on the bottom of the heater and the sides of the firebox. From your experience, it sounds like its definitely worth using some of that heat to preheat the combustion air to encourage gasification. I look forward to sharing my experience in building and testing the stove for my house heating needs, and thanks again for all the great advice. Cheers, -7
I've been researching for an R-stove build for some time now and recently stumbled upon a blog on which a University professor, whom, according to his credentials is extremely well-educated and qualified specifically in the field of thermal mass heat transfer, commented that one of the more common errors he sees made in the 'home' development of R-stoves is having a flat-topped heat exchanger. It should always be rounded, so as to disperse the heat more 'evenly'. Having a 'hotspot', can result in a burnout. Especially dangerous are the thin metal drums being used. They are not designed to withstand the intense heat. Your much heavier-metal top warping would seem to validate his comments. That said... your design is 'numero-uno' in my book. I will be using your design as my guide... but will incorporate a dome-shaped top. Excellent work... I especially enjoy your gently put 'no-muss, no-fuss' commentary skills!
Richard Workman Hi Richard and thanks for the comment, id agree it makes sense to have a domed top to the exchanger, saying that i suppose you could weld a smaller domed plate on the underside of a larger flat top such as mine which would then throw the heat down the exchanger walls faster, the top would still get hot with the residual heat inside. And if the dome was spaced off the top slightly it would further reduce the transfer, kind of what i did to fix this stove by welding a large thick circular saw blade under the top inside with a three quarter inch gap over it, it has had the desired effect and now the exchanger walls are roughly the same temp as the top. I may weld the top off the old stove underneath next time i take the top off see how that changes things. Thanks again.
***** Excellent Idea... A more reasonable 'reverse' of what I was thinking of doing. I had thought of having a dome top with a flat plate (supported by legs) that would enable the use of the hot surface for a tea pot or cooking pan, etc. I would really love to see your results of adding the 'dome heat disperser' from your old stove to the interior as you've suggested before I get started on mine. It would greatly simplify my build and... if successful... it might also make a highly-recommended retrofit for all those that have used the less-safe, thin-metal drums.
Richard Workman What about shielding the metal of the top with some kind of refractory? If you added brackets to the underside of the top and hung a kiln shelf or something directly above the riser?
Oxbow Farm When it comes to using flat-topped barrels, that might prevent an 'open exposure' from burnout ... but I'm not so sure that premature degradation would not still eventually occur (albeit delayed some). It also doesn't address the added efficiency to be gained by the more even internal distribution from a dome-shaped top. However, since adding a saw blade 'inner plate', it would seem that Ppotty1's design is working well enough for his needs... so I guess that "says it all". I will, however, be interested in hearing if he realizes any added benefit should he ever decide to experiment by adding a dome-shaped 'diverter' to the internal top of this stove.
Makes my hands itch, when I see this kind of craftmanship :-) Going to search for a couple of old gastanks and asemble my own very shortly! :-) You're a true inspiration! :-)
Sweet. Don"t loose the door. It is totally worth seeing the fire. even if you sacrifice some efficiency. Your stove is now (I think) the best on the Tube. Well Done Sir!
Your refractory and perlite/vermiculite mix, I don't remember which you used, but I fail to see much difference between them, is the one I plan to use, though I plan to use Sonotube® as a mold for my horizontal to riser section.I have figured out how to make a spiral channel with an embeded steel tube in that spiral channel to bring air. Just attach to the tube, and let the material I make the channel with, wood, burn out, leaving the metal tube, which was attached to the wood in the recess. I had thought to make the batch box casted, and want to try it in the future, but I have a metal fire box in need of a home, built in the same configuration as yours, top load, horizontal chimney, as part of a smoker.
Wow! You're a Godsend. I was having the same problem. My insulated burn area gets too hot after about 2 hours and then my draft gets weaker and the burn chamber gets too hot. This is a problem because my system is a gravity fed pellet system. When the burn chamber gets too hot, the pellets gasify early and it's completely unhelpful. I got a couple of fires in my hopper and between your video and another, I realize that I need to remove the insulation around the burn chamber.
Jamal Johnson Hi Jamal glad my video could help you figure out your problems...did you build the heater yourself ? i remember trying2lhard was building his pellet feed with that problem in mind. Cheers.
***** Yeah, I built it myself. I only have only 25 inches of vertical clearance in which to cram my ash tray, my horizontal burn chamber, my riser and 2 inches of insulation above my riser. This leaves me with a 14 inch riser. So my draw is meager and can't afford to suffer from that early gasification problem. I wonder if changing the diameter of the riser is gonna change the draw strength. Currently the riser tube is 4 x 4 inches (100x100 mil). Anyway... I just dugout all of that insulation around the burn chamber. Test burning it right now. You da man
Jamal Johnson Hey Jamal good luck with the changes..a bigger diameter riser would obviously move more gas through the system and have a stronger draw if you reduced its size at the entrance, like you say its fairly short in length but I think a 5 inch riser would improve things how much I cant answer. Cheers.
Thank you for the speedy reply. I am going to put your idea into action this autumn and let you know how it goes. I will be in touch again when I begin. awesome videos and thanks for sharing. All the best
I'm looking at my woodwarm stove right now which is great and pretty efficient and we use about 1/4 of what we'd burn on open fire but keep the house warm enough just with that. However seeing yours kicking out 300 cent on 3 little logs for a couple of hours knocks ours into the long grass! Slightly worrying with the varnish melting though, put something like yours in the living room and we'd burn the fuckiin house down! Brilliant vid series chap and a lot of food for thought. Thank you!
I found that in my stove it is radiant heat comming from your door window and not convective heat. So I would leave your window great vid by the way ;)
140 F is a low flue temperature (60C) I would not worry about it, you need some "rise" after leaving the chimney to carry the condensate you sometimes get away from the building.
You've got the sickness my friend, The Fire Bug Sickness lol. All kidding aside it's an awesome stove and I'll bet you get years of service out of it. Just like tryin2lhard I was wondering about that old stove autopsy though. I think building one like that would be more my speed, At least for my first one lol. (I'm not much of a welder yet) Thanks for sharing all your work and experiments with us. ATB, Steve...
Brilliant, brilliant, brilliant, well done mate! Having watched quite a few rocket stove videos, I've come to realise that yours is one of the best! Congrats! I think it's well thought and put together and very economical. To get so much heat from so little wood is amazing! With regards to the top plate, I would put a slab of thick cast iron. It would definitely not bulge. Crikey, I would even make the exchanger from cast iron, just imagine how much heat you can store in it! I've got a few questions for you - should you have the time to answer them - it would be much appreciated! So here is the story: I'm running a joinery business and renting this out building that I heat with a 23kW wood stove (no gas supply here!). I knew about rocket stoves before I bought it but my workshop consists of three individual rooms, so had to go for the boiler version. Given its power rating, I knew I would be burning wood by the barrow but since there are quite a few construction sites around that skip a lot of wood, I thought I would not run out of fuel - which I haven't anyway. Still, I am not very happy that I go through more than half a cubic metre of softwood a day. Even though I get it for free, it's still a waste, plus it takes time to cut it and load the stove every 15 mins or so! I would be spending about an hour a day doing only this - that's an hour longer at work. But don't get me wrong, the stove works beautifully even though it's o no-name Chinese made. The plumbing is simple and leak free, it chucks out serious heat, quickly heats up the water and all 6 big double panel radiators are kept at 70°C all day - cushty! Even so, watching your videos I had the thought of asking you this: do you have a solution for a boiler rocket stove? That would be a heat exchanger whose sides and back are the boiler (or only the back). Did you give it a thought until now? I can only imagine how efficient it would be if installed inside the house and supply hot water and heating for only a fraction of the cost a normal stove requires.... Cheers!
cinamaster Thanks mate, interesting story as my friend heats his woodwork shop the same as you from a similar stove with water heater and rads around the place, i know he uses tons of wood in a winter too and spends alot of time cutting stacking and loading it into the stove. I think he could fit a rocket stove alongside it and connect it into the existing flue for the days when the temp inside just needs a boost using only the rocket. I have done some work on boilers in my earlier videos and intend to follow it up at some point and actually build a full working model which will look alot like this stove from the outside. I also want to scale it down so it can be used indoors with the aim of getting it approved for residential use, (well thats the dream scenario) if not guys can build it for themself. ruclips.net/video/FLcIrrHjdUM/видео.html this is the video that shows the basic idea with combined firebox and exchanger fitted with wrap around boiler the front of firebox would have a glass door. Cheers.
Thank you ppotty1 for this excellent info. I intend on building one into a thermal mass possible underfoot in an earthen floor. I particularly like your findings regarding the slowing down of the draw or keeping the heat in the box longer. Have you considered adding some thermal mass inside the combustion chamber, between the cast riser and the exchanger. Maybe a pumice allowing for air to pass through but much slower.
Skill Billy thanks mate, I have seen volcanic rock used inside stoves to further clean the gasses and to add thermal mass its something i may try. Cheers.
OMG that is really hot!! You got it right again ppotty1. Very nice project! Anyway Happy New Year to all Stovie Guys.. Good Luck and most of all God Bless.
Just a thought about your comments about pre heating the primary air thats being fed by the ambient air in and around your stove within the envelope of your shed, cold air expands. Just like a hot air balloon as its heated it produces positive pressure which carries heat with it and if you fed your primary air directly from the outside the effect is no air is needed from the leaky drafty spots around your door and windows. Every modern stove built since 1970s have this ability and has become a better practice and procedure. I'm not being cheeky and admire the interest you share. Its just worth using the gains you have recieved with insulation and balance it without compromising the radiant properties a steel structure exhibits. Batch box rocket stoves are quick heat heat up but the also cool down quick. Try a highly insulated bell bench on that back wall with thick capping stones for thermal mass to help retain that lovely heat and perhaps you'll find you need to burn even less wood and that heat will be more even and last longer. Cheers
Hi Matt, yes the primary air is fed in from the outside on this stove and gets pre heated in its way into the firebox, but i never really wanted to build a permanent mass around the flue, as of now I am going to move the flue into another building attached to this one, this should provide all the heat I need for it, cheers
@@LozHarrop Forgive me if misread the lenght of the primary air feed tube, I assumed you hadn't extended the 2 feet of box pipe I saw as your feed tube to extend to the outside of the building. In all fairness the connection wasn't made clear in the video. Im also at odds with the idea feeding a combustion chamber with cold air because it expands vs protecting the point of combustion with the use of insulation which results in the highest possible temps and therefore results in the cleanest burn. My thought is your work up in the front end is excellent and I personally wouldn't change a thing. My comment about what you do on the back end past the riser wasnt fair either as i didnt concider the back wall being made of concrete. I live in a province within Canada that has extreme low temps in the north (-60c) and on the island portion we have the highest sustained winds on the planet. We wouldn't build a structure that hadn't had insulation (thermal break) and a completely sealed vapour barrier on the winter warm side. Our thermal mass is highly insulated and contained within the buildings envelope. Its hard for me as a British ex-pat living in the new world to make a suggestion back in the homeland where it's tradional to do things in a certain way. My interest is to soak up all the wonderful things you are doing and add my thoughts in order to reciprocate. Keep up the good work.
Impressive achievement, P! I've studied rockets for a long time, and built quite a few. I do all my heating and cooking with them now. But I've still learned a lot of useful insights from watching your videos. I'm building a rocket with radically-changed geometry right now (though with all the basic Aprovecho-derived construction/function principles still maintained), and your work here has given me lots of useful demonstration that what I have in mind will work fine. Many thanks! And great to hear that old accent of my childhood too, for a bonus. :) Outstanding work. Tryin2hard could well be right: Best rocket on the net - or one of the few best. Cheers, RhG
Rhisiart Gwilym Hi RhG, Thanks for your comment I am happy that you found the video of value and hope you go on to making something that fits your needs. You still got the accent lol...cheers.
Great videos bud joy to watch! Just an Idea for your pre heat, can you use a pipe within a pipe. Outside being your inlet & exhaust being the middle thus take more heat out of you flue exit temp. Maybe insulate with another pipe around inlet/exit pipe with ceramic insulation in the gap. This also makes it fail room sealed so you could insulate your workshop and save the heat your producing. Keep up the good work!
Arron Potter Thanks for the comment Arron, I thought briefly of doing that around the bottom horizontal flue section but the fabrication put me off the idea, i think some movement through the exchanger would be good thats the hottest part of the system and fairly easy to fabricate and connect. Cheers.
I'm thinking of building a heat jacket around my stove and using a blower (off my other woodstove) and blowing the heat into my ductwork to heat the entire building. With that kind of heat produced, it needs to be routed where it's needed.
I really appreciate your work on these stoves as I hope to build an RS with water heater for my 50's bungalow in SE England so I feel your 'uk centric' research and experimentation invaluable. I have reasonable mig welding and fabrication skills although I have yet to even light let alone build a RS! May I bother your for two quick questions pls? The first question is based on the premis that I am not sure if you have produced any research findings on water heating RS's. 1. If I were to install a ( copper or steel ?) water coil inside the heat exchanger, around a refractory riser, what proximity or touching, could the coil wind around the riser, having seen your risers glowing red. 2. When purchasing the sheet steel do you worry about the grade? Prices vary for 8x4 sheets from £130 to £350. Many thanks from Duncan Southend on Sea
Hi Duncan, The inside does glow red but the outside is much colder, you could have the coil touching the outside of the riser without any problem, I have always used cheap mild steel sheet sometimes scrap when i can get it. Cheers.
I think I'll also make my riser tank to be bolted on at the bottom so be able to make the entire stove in pieces, for ease of installation and inspection. Also line the firebox with fire brick or pour it with refractory cement, the same as the riser. My idea is to make it big enough to get a long burn time and better control of the temperature, so I can turn it down (I don't need 1000 degrees running temp) The pellet feed I have fabricated and works exceptionally well, so I'll also have that option when the time comes. I found the heat from the pellet burner are able to be controlled for a more even heat. Thanks for all the info!!
Painter D Good to hear the pellet feeder is working well, its more than well worth the small effort to make these stoves modular, its just so easy to then take things apart to inspect repair or replace them. My old welded up stove has to be now cut up to take it apart, that process will destroy everything. Cheers.
Nice report, really like your stove. Was thinking on doing the same as for insulating a future project\stove. If your redoing your topplate and want to really pre-heat your air inlet, why not constructing a second chamber above the reisertube and use that blast to heat your air, guide it inside your heatexchanger, into the firebox. You cant het hotter air then that. Make the second Chamber wide, so the air can slowly heat up. You wont lose that heat as you reuse it inside the heat exchanger. Maybe you have a faster start of a clean burn. Hope this helps. Greetz
Kim Lesage Hi Kim, and thanks. Problem with pre heating air is once you heat it as you know it gets much lighter and just wants to rise, it will have a negative effect trying to naturally force very hot air down into the firebox, my thoughts are that the air needs to be fed in on a rising or at least level path, it would work that way if a small fan was fitted to push or pull the air down though. I would try and feed the air through the exchanger on some kind of baffle or similar to the copper sec air feed on this but using 2 much larger tubes to feed to each side of the firebox. Cheers.
***** hey, been thinking about your respons for all day now :-) Your right, hot air wants to rise, but wont the hotter air from the risertube suck in the less hotter air from this preheating section? It can slow down, but you've narrowed the inlet before. Maybe it the stove will be able to adjust its self? I going to try it in my future project, somewhere in 2015. Cheers
please give it a try mate and see what think, hopefully my thinking might be wrong and if so its a new idea that will be worth putting to use...Cheers.
Just watched this series of videos on the new stove, as well as the autopsy of the old one. Brilliant work. My build was delayed until January due to some uncontrollable issues, however I'm kind of glad it did; now I've got some new design parameters to throw in. I've got some air preheating ideas to work on; I'll let you know how it goes.
J.D. Ray Nice one J D sometimes pays to wait a while, I know someone will no doubt improve on the things I have done on this stove once they get to work on a build, main reason I put out my builds as we all get something back in improvements later down the line. cheers and look forward to seeing what you come up with.
+utubeaccess7 Thanks for the comment bringing the primary air directly through the exchanger into the sides of the firebox would really improve the pre heating and could be done really easy. Cheers.
I think you built an awsome rocket stove. You put your thoughts in the design, changed them when you weren't satisfied with it and the end result is a killer. I was wondering if instead of wood the rocket stove could also run on coal briquettes? Have you ever tried that? Coal briquettes burn very slowly and as far as I know they are cheap. A disadvantage is that they produce more ashes than wood, but perhaps the rocket stove's high temperature also burns coal briquettes more efficiently.
Your experience and craftsmanship is much appreciated, thanks for sharing. I am getting ready to build a stove for my 16x20 canvas wall tent. I've decided to cast the riser and fire box with the same mix as you have done. Obviously weight will be more of a factor for me but the trade of will be worth it. One thing I'm considering is only casting the riser , half as tall than use stainless steel the rest of the way. The dimensions I am thinking are: 5" diameter riser, 34" tall Fire box : 8"x10"x12" Heat exchanger: 18"x18"x36" I'm guessing on these, I haven't been able to find any formula , it looks like you are about 61/2 inches in diameter on your riser, can't tell on your flu, Any chance you can share some of the dimensions you have dialed in? Thanks so much.
Rodney Ficklin Hi Rodney and thanks, The dimensions you give sound ok to me and should be good. I totally forgot to put the dimensions of this stove on the end of the video sorry. Will sort it out and put another short vid up giving all the dimensions and anything I would change to improve this. Cheers.
greetings Potty. thank you for sharing your design. the metal fabrication was great but the vortex draw on the cast riser was awesome!! your design is an inspiration, and a confirmation of ideas about a cast riser. What are your thoughts on adding a wet heat exchanger to a stove like this to heat water for underfloor heating / radiators / bathrooms?
+Sony Droid Cheers, This stove would take a water jacket or a coiled pipe set up to heat water, if coiled around the outside of the riser it wouldn't effect the temps inside due to the riser thickness, a water jacket on the top or sides of the exchanger would equally work well, Ideally you would have a big water tank as the heat store and draw the heat off that through the pipe work, unless you dont mind tending the fire to generate the heat as you need it.
Thank you for sharing your whole process! I have been doing my research and was thinking of casting a section as you have, so it's good to have gained that experience here in my pajamas this morning! : ). Just a thought regarding the primary and secondary preheat. So a preheat through a passage bonded to the exchanger as you have proposed . Also, make that a dual passage, one for the primary and one for the secondary . It seems to be of benefit to have the secondary air as hot as possible as well . rocketstove.nl has his "s-tube" heater . Looking at that I'm a bit leary of putting any metal in the path of the burn/ blast but its a good example to get the thought process going. Where to get the most heat ? Well you had that problem with the lid turning blue, that might be a good spot to pass the air , cooling the lid and getting that combustion air as hot as. A bit of a puzzle with passage and gasketing to retain the lids function as a lid. So, that's my thoughts . thanks again, great videos, great design. When i go to make my stove I will have derived a good advance in experience from this.
Fantastic videos! Could you summarise, please, all the advantages of the secondary air intake? It's a lot of work to put one in if I made one of these and ,being a novice, I don't understand the advantages of secondary air. I understand everything else. I dare say you mention it on one of your earlier videos but I must have missed it if you did. Apologies and thanks again for the brilliant films.
jazborocketman Hi There and thanks, Sec air simply puts extra oxygen into the riser which burns any gasses that remain after combustion in the firebox, on this stove as I shut down the primary air supply to the firebox, when the firebox is hot enough to gas the timber, the sec air supply can be fed in to ignite any gasses inside the riser without passing more air over the timber in the firebox. Hope that explains it. Cheers.
Great. Thanks for that. Just what I need to know. I'm going to make a stove a bit like yours but I'm using a pumice flue liner and other bits made by Isokern instead of the cast riser. I'll let you know how I get on.
Well, what can one say? Brilliant design and brilliant execution - just really well thought out from stem to stern. For me I'd say the most critical element of your improved design is the modularization utilizing the refractory cement chamber and flue constructed as consumable item. Conceptually there are breakthroughs increasing efficiency with regards to pre-heating, secondary air injection and it's attendant issues (location, rising, etc), entraining heat in the fuel box to promote gasification, etc; but the modularization is what allows the design to become practical as the whole stove doesn't become consumable item ;-） I'm curious to know about your adding pearlite to the refractory cement as it's primary purpose is to insulate, but in that portion of the burn cycle I don't see the need to insulate the column. Why not just cast 100% refractory cement whilst adding a bit of glass for structure and tensile strength?
***** Hi Scott, thanks for the comments, I remember being unable to reply to your comment maybe due to your google privacy settings, But to answer your question I added perlite as an insulator to try and keep some heat in the riser and so the riser would heat up faster, solid refractory soaks up and robs heat where as a lighter refractory does the opposite, the amount I added probably did not make a huge difference but im sure it had some effect, since casting this riser I have found a much better alternative and will be casting another riser shortly to try it out. Cheers.
brilliant ,need to get off my lazy arse clean out garage try make some pigeon boxes will be using calor gas heater .would love your set up but my place to small really enjoy your channel. cheers
Thinking of putting a rise on top of my wood stove . Controlling the air flow with the door . Tank over too and long pipe for the chimney. Your thoughts
hi and well done for the series on this project my question is about the riser how is it holding up and would you change it for a more insulation type material to hold in the heat also have you had any thoughts on a front window of the firebox? cheers mate
+dusty saunders Hi Dusty, The riser is fine mate still as good as when i fitted it, more insulation would be good but this dense kind also has its benefits giving off stored heat when the fire has gone out.... just doing some mods on the stove at the moment, I wont be having a door on the front just easier if its on the top. Cheers.
Hi, Great videos with a lot of thought behind them. You seem to have worked out that the hotter the incoming air, the faster the gasification so the more efficient the burn. I noticed that you lined the firebox and also the outside. Would you not increase the heat of the incoming air be removing the insulation from the inside of the firebox and maybe putting fins on the outside where the air travels up and enters the top. I know it might seem that this will reduce the heat inside the firebox but as I see it, you are lowering the burn temperature by introducing air that is cooler (I know its very hot) but cooler than it could be anyway. think you might get an overall gain as the incoming air will heat faster on the large surface area of the outside of the firebox. By the time it gets to the fire it should be closer to the fire temperature. My thinking is similar to how a TLUD heats the incoming air on the outside of the internal firebox. If this works you might have to make the walls of the firebox sacrificial though. You do great work, Thanks.
+Boatman's Bolt Hi There, and thanks, I see your reasoning and I had the same conflict when i was working on this. I had a couple of test burns before lining the firebox to see how it all performed but believe me when i lined the firebox the difference was obvious in the gassing. Despite the lining the heat still gets through to the walls of the firebox and is transferred into the incoming air and it works really well, as you said a stand alone metal lining would not last long. The lining has the added effect of storing heat inside the firebox were steel would cool down very quickly one the fuel burns down. So the lining is not really a compromise it actually has benefits. Cheers.
Hi again, I'm still at the design stage an wondering about a few things, I would really appreciate your input: Primarily the same basic design as yours but with a cast firebox with the primary air, coming through ducts or holes cast into the bottom of the heat exchanger/burn tube casting, and feeding the top of the firebox. Do you think this will produce enough preheating of the primary air to get good gasification like in your design. I am also wondering if the secondary air inlet into the bottom of the flue should be placed at the tip of the narrowing entrance to the flue so that it acts like a venturi. I thinking it might suck more or speed the incoming air and could maybe be jetted to improve the vortex and mixing. I'm thinking of using thick wall cardboard tubes as the mould for the riser and mainly strong cardboard for constructing the rest of the mould (it might need waterproofing) so I can just burn it out, once it has set. This would allow complicated shapes to be easily and cheaply constructed. Your views would be greatly appreciated. I think you have one of the best stove designs on the net and thank you for sharing it.
Hi Cant really comment on how hot your primary air will get if placed as you say, where i to re-do mine I would maybe run copper tubes through the exchanger or some kind of ducting to get max heat into the air i know i could really improve mine if i tried and had known how much the pre heating improves the output of the stove. I tried several places for the sec air to enter and this was the one that worked the best for me but different designs may respond better if the air entrance is somewhere else, you just gotta try things out as all rockets are different in some respects, the cardboard tube idea is sound and can be burned out later easily, cheers.
Congraats! And Thank you so much for the detail explanation on your rocket stove! I have a dumb question, though. What makes the flues go inside the riser instead of coming back on the fire boxx? I am trying to adapt your project into a rocket stove cooker/oven to be on a kitchen. I woulldnt wat to have smoke coming back through the firebox, and the test I have done showed that the fire was beeing feb by the riser and burning backwards! Thanx again! Mauricio, Brasil
+Maurício Möller de Oliveira Hi there, if the fire is burning out of the firebox then either the firebox is too big for the riser to deal with or there is not enough gap over the top of the riser which wont allow the gasses to escape fast enough. cheers.
I was thinking the same thing - two panes of glass, (I believe shooting your IR temp sensor at glass will give you the glass temp not what is behind it) Great idea on casting the fire box liner! Truly love your stove videos, ppotty1, well done indeed!
laura taylor Hi There, and thanks, now the firebox is insulated and the steel protected form the fire I cant see this stove degrading at all, I think the first thing to go will be the flue which is very thin steel. After two months of using this stove it still remains as good as the day I first lit it so I think it will outlive me.
In regards to preheating the air, a tortuous path with lots of fins? I like the idea of having it flow around the heat exchanger. But, how can you create a flow of that heated air into the room?
It would be self propelled. The rising heat starts the blades turning, which then causes a vacuum which causes more heat to move towards the fan which causes the fan to continue to turn. Self perpetuating? Is that the word? For instance, on the older jet engines, once it started, the exhaust hit fan blades connected to an (axis - rod) that turned the turbine in the front. So the exhaust then turned the turbine. That's not the whole system but you get my meaning?
have a look at peter van den bergs rocket heaters ,there is some craisy heating going over there plans can be found on face book rocket stove /rocket mass heaters
I would like to build a similar stove to heat my cabin but I'd also like to see the flames when sitting around the fire. Do you think it would create any issues if the glass was on the front instead of the top? Is there a limit as to how large the firebox can be? Ideally I would like to achieve an overnight burn as well.
Phil Tyers Door would work fine on the front with no problems I can think of, you could in theory make the firebox very big however if its too big it will overwhelm the gasses the riser can take so it will burn dirty then vent out flames when you open the door, i think the firebox on this stove could easily be 4 inch wider and 4 inch higher without any issues, you could make a large light weight temp test box just to find out how big you could go, do some test burns and if too big and fire gets out of control or stalls due to lack of air or riser flow place firebrick inside to reduce the internal size and test again, keep adding filler until you find the ideal size that the riser can cope with. Cheers.
Hi there, I'm just catching up on your rocket stove videos, I like both of your builds very much. But why aren't you using the same exhaust system on your second build. I think it's quite brilliant to use a very long exhaust so more heat can be transfered to your workshop. Regards, Alex
Hi There I dont really need the heat output from the flue with this stove but also the new flue was scrap and was not long enough to replace the old one in length, the stove vents much better with this too.
Has the flu pipe cooled down now that you have insulated the outsides??? Just wondering if your losing much heat up through the flu? Thank you for sharing your knowledge with us : )
scramblendan No problem, the flue temps are pretty much the same as the last rocket stove actually, I have since taken the temp readings from the horizontal flues behind the bench and they match what the old stove was putting out burning flat out. This burns slower but achieves the same temps as the old one which is a big improvement.The radiated and rising heat from the exchanger has caused the increase in temps to the vertical flue above it. Cheers.
Instead of insulating the firebox what do you think to a disposable 10g inner liner? It would get red hot in no time to aid gasification and after a few weeks just throw it away when it distorts and fails.
Hi Dan Same answer here as your other question, you need around 3 inches gap over the riser tube or you can choke it up its better to have more gap for the gasses to escape
ppotty, seeing you do the casting, it looks really easy and simple. Then seeing that you had to line the inside of the fire box, what do you think about casting the fire box, (four sides and bottom) then just using thinner metal to make the air passages? what do you think?
Rick Taron Hi Rick yes you could probably do that and all would be fine, when you look at my old firebox the outer 2mm steel on the sides has suffered no damage because it was protected just by that thin piece on the inside. I would say 3mm would be perfect, that is what i have used on my new exchanger and the outer casing of my new firebox. cheers.
***** Happy new year! I am working on a stove build that will heat my storage tank of hot water. 1000 gal. so, I think will make something similar to your heat exchanger but just add about 80 ft. or so of 3/4" soft copper tubing, circling the riser tube. I will draw something up to share with you. thanks again!
Rick Taron happy new year rick, you could circle the copper around the inside walls of the exchanger weld some lugs on for it to sit on, you would get much more copper inside the exchanger and it would still get very hot, this would allow you to change/swap the riser easily if it needed replacing. Cheers.
***** dl.dropboxusercontent.com/u/16468811/wood%20water%20heater.pdf here is what I was first thinking about using two 55 gal drums for the heat exchanger with insulation all around. but seeing the trouble you had with sealing between the burn chamber , round to square looks even harder. I'm thinking maybe a square heat exchanger might be easier. with just one shared wall between the burn box and the exchanger. back to the drawing board.
Steel warps with heat I don't agree it is most efficient. When I use the term ceramic I am referring to the material you are using to construct the inner section which is a concrete fire mix. Round would be better than square as it would allow the heat to distribute out evenly. Possibly using steel to encase the ceramic could be a possibly. Over all are you happy with the performance of the stove and the design meaning a rocket stove? I find the Russian stove a unique design as well.
The exchanger body never gets hot enough to suffer from heat damage, just the top tends to distort from the heat directly over the riser, but yes ceramic riser and firebox etc all good for longevity. The stove is great in operation and performance my shop has been warmer than the house this week and im hardly burning a barrow full of wood a week. Yes im in the UK north west.
Thanks for the review. On my square heat exchanger, instead of the angle iron fins, I went ahead and cut slits through the exchanger then welded in 1/8" steel strips, 2" to the inside and 3" to the outside. The fins on the outside are shrouded with an aluminum panel open at the bottom and top for convection. Question: What is the diameter of your flue pipe?
***** LOL at myself. Been using 4", probably why the draft is poor at WOT, otherwise it's OK. I'll open mine up to 6". Hey, I noticed you're wearing the same hat as last year. Want one from the states?
Norman Kellison Yes they would but a steel plate is easier to fit, I intend to fix a piece of glass in the top directly above the riser to see what is happening in there which will be interesting seeing the effect of the sec air and the gassing stage.
Awesome work. Just amazing. So many youtubers claiming to invent things they didn't, but you really made a better rocket stove. I do feel a little insulted every time you say "fellas". I'm sure most of your viewers are guys, but you really make the assumption that you have no female fans and you soooo do.
My thoughts on which way your vortex should go in your location if you fill your bathtub with water and start letting it drain if you notice which way the water drains! for example the water will turn a specific way as with the earth is turning I assume the fire vortex would turn in the same way this advantage it will create a natural turn of the vortex. if a person would be in Australia the vortex would be turning in the opposite direction. Do you have a idea of what I am trying to communicate to you? would this make sense!
you would have to agree if it turns naturally one way with the law of gravity if you send it the opposite way it would be fighting itself constantly. It would be more efficient turning the rite way. It would be more efficient this way. What exactly does cheers mean? Here when we use cheers usually two would raise glasses and say cheers It is a way to say I agree with you. In what context do Brits use it?
Hey ppotty1, Thanks for the vidoes! After watching yours I was checking out some videos over at T2H Instructionals. He mentions in a video that he uses stainless as a heat riser and has never had one degrade. I have seen elsewhere that stainless will degrade. I was planning to do a cast refractory core similar to your build you have shared with us here. Can you speak a bit to the reasons you ended up doing a cast riser and what some of the pros or cons may be? Thanks in advance!
+Wesley Aycock You may know there are different grades of stainless some being more suitable for risers than others, no matter the grade though if you put very high temps onto it for long periods it will degrade eventually. Ive always wanted to try a cast riser because i always used steel in the past im pleased with it and it has suffered no damage in the last year. pros are it holds alot of heat which goes into the exchanger when the fire is out and once lit and heated the stove draught's better, only drawback is it takes time to build and longer to heat up but as said the stored heat you get back anyway. costs of stainless and casting are roughly the same. I prefer cast over stainless for this type of stove. Cheers.
+ppotty1 Great! Thank you for the input. I will continue onward with my casting attempt. I'm planning to use a refractory cement called Secar 71 mixed with perlite.
Thanks for the reply. I love your work I can watch rocket heater videos for hours and your is one of the best. I need one to heat my house its about 1100sf but holds temp pretty good I use a kings wood circulator works good just uses a lot of wood.
@@LozHarrop do you have to keep exhaust pipe from stove rising ,you mentioned in on of your videos that your flexi pipe was 6inch dia and 4m long would you get away with 4inch and 6m long ,as I want to run through a heat sinc to dry timber,if I used sawdust would the ash build up quickly or would I get away with cleaning once a month through a removable plate at bottom of heat exchanger,thanks for quick response and greatly appreciate you sharing your knowledge. Charlie
@@charliecass6717 you could run it dead flat but the condensation inside the flue would just lie in there, i was given a new roll of 4 inch ss flue but its just too small for the size of the riser i have, pretty sure it would get choked up on my stove, if i had a 4 inch riser i would give it a try though. However a 4 inch riser would reduce the size of the firebox you could use. Yes have an access plate on the exchanger to suck out the ash every few months and it would be fine, good idea to have one or have access to the bottom of the flue as it may also start to build up in there.
Ppotty1... Have you ever tried a cast iron pipe as the inner liner of a riser? I have one available to me and was wondering if you (or anyone else out there) might have had an experience... good or bad... by using a cast iron pipe surrounded by insulation as the riser.
***** Thanks... Since I have a length of 4" cast-iron pipe readily available, I will likely 'putz' around with using it as the inner liner of a smaller-scaled heater than your own and let you know the results.
Hey ppotty1, I love your stove, and all of the thought you've put into it. The air-preheating system is ingenious. I am very interested in building my own and have a number of designs floating around in my head. Every day, I peek in an industrial dumpster on my way to my car, and today the gods have smiled on me, and deposited one of these - www.bloklandnonferro.nl/en/cowl_silencer.html - a "cowl silencer". Mine is made by Phillips & Temro. I was wondering if you'd ever seen such a thing. It seems like it would be an ideal component for a rocket stove. I'm thinking an insulated heat riser could just be made that would fit up the central sleeve, and the vortex would continue throughout the spiral silencer, and the internal spiral surface area should be pretty effective at sucking the heat from the exhaust. What do you think? The design does not lend itself to effectively preheating the intake air like yours, but it seems pretty promising. Lastly, if the thing has insulative steel wool stuff in there, would I have to get it out? I'm certainly not the welder you are, and would likely do more damage than good. Anyways, just love to hear your thoughts.
For the life of me, I can‘t see why you keep insulating everything. The whole idea IS for heat "to escape" to actually heat the room. Pretty soon, all the heat will be forced up the flue. Your concept is great.....but you are overboard on the outer insulation, in my humble opinion. Waiting for next video.
You're welcomed!! I really like your heater. I think you put a lot of forethought into it. It is one serious heater, in my opinion. Wish I could get one like it. I know with the time and material, it would probably be out of my budget. I'll keep watching to see how you do with it.
22justus24U Don't get mad, I'll try to be nice. But you know what sarcasm is don't you? If you re-watch the videos he explains pretty well why he's insulating the fire box so well. We want to keep as much heat in the fire box as possible to insure a complete burn of the fuel, then remove that heat with the heat exchanger as the hot gas's pass through it. Unburnt fuel will condense in the exchanger and chimney, wasting fuel and forming creosote buildup which is a fire hazard. If you do a little research on outdoor wood boilers you'll find that many can burn 12 cords of wood or more in a season. Much of that is because heat is extracted from the still burning flame, that cooling effectively extinguishes the flame and the rest of the unburnt fuel goes out the stack as smoke. One guy lined the bottom half of his outdoor boiler with fire brick and a cement board across the top of that. He got the same amount of heat out of it but only burnt 1/2 the wood he did before.
I definitely want to take a welding class now. I can't wait to get my son to watch this. Now, he's a welder. Thank you for taking the time to share your knowledge. God bless you.
+agape713 thank you and happy welding much easier to weld up a rocket stove than split endless logs and put the heat up the chimney.
ppotty1,
Thanks so much for this video series. I've been researching 'rocket' style heaters for over 3 years, and this series has been by far the best first-hand information I have come across about (non-mass storage) heater design and testing.
I'm beginning the design and build of a heater for my house, a bit smaller than the size of yours and I plan to use many of the features you've improved upon with this model. One of the major differences in my design will be the predominant use of homemade refractory materials over steel (wherever possible), in order to reduce the cost of the build.
Before you mentioned an 'easier way to preheat the combustion air' in this video, I was thinking the exact same thing - you have much higher temperatures available within the heat exchanger volumes than you have on the bottom of the heater and the sides of the firebox. From your experience, it sounds like its definitely worth using some of that heat to preheat the combustion air to encourage gasification.
I look forward to sharing my experience in building and testing the stove for my house heating needs, and thanks again for all the great advice.
Cheers,
-7
I've been researching for an R-stove build for some time now and recently stumbled upon a blog on which a University professor, whom, according to his credentials is extremely well-educated and qualified specifically in the field of thermal mass heat transfer, commented that one of the more common errors he sees made in the 'home' development of R-stoves is having a flat-topped heat exchanger. It should always be rounded, so as to disperse the heat more 'evenly'. Having a 'hotspot', can result in a burnout. Especially dangerous are the thin metal drums being used. They are not designed to withstand the intense heat. Your much heavier-metal top warping would seem to validate his comments. That said... your design is 'numero-uno' in my book. I will be using your design as my guide... but will incorporate a dome-shaped top. Excellent work... I especially enjoy your gently put 'no-muss, no-fuss' commentary skills!
Richard Workman Hi Richard and thanks for the comment, id agree it makes sense to have a domed top to the exchanger, saying that i suppose you could weld a smaller domed plate on the underside of a larger flat top such as mine which would then throw the heat down the exchanger walls faster, the top would still get hot with the residual heat inside. And if the dome was spaced off the top slightly it would further reduce the transfer, kind of what i did to fix this stove by welding a large thick circular saw blade under the top inside with a three quarter inch gap over it, it has had the desired effect and now the exchanger walls are roughly the same temp as the top. I may weld the top off the old stove underneath next time i take the top off see how that changes things. Thanks again.
***** Excellent Idea... A more reasonable 'reverse' of what I was thinking of doing. I had thought of having a dome top with a flat plate (supported by legs) that would enable the use of the hot surface for a tea pot or cooking pan, etc. I would really love to see your results of adding the 'dome heat disperser' from your old stove to the interior as you've suggested before I get started on mine. It would greatly simplify my build and... if successful... it might also make a highly-recommended retrofit for all those that have used the less-safe, thin-metal drums.
Richard Workman What about shielding the metal of the top with some kind of refractory? If you added brackets to the underside of the top and hung a kiln shelf or something directly above the riser?
Oxbow Farm When it comes to using flat-topped barrels, that might prevent an 'open exposure' from burnout ... but I'm not so sure that premature degradation would not still eventually occur (albeit delayed some). It also doesn't address the added efficiency to be gained by the more even internal distribution from a dome-shaped top. However, since adding a saw blade 'inner plate', it would seem that Ppotty1's design is working well enough for his needs... so I guess that "says it all". I will, however, be interested in hearing if he realizes any added benefit should he ever decide to experiment by adding a dome-shaped 'diverter' to the internal top of this stove.
Makes my hands itch, when I see this kind of craftmanship :-) Going to search for a couple of old gastanks and asemble my own very shortly! :-) You're a true inspiration! :-)
andreas heijdendael Thanks andreas you wont regret building one when you feel the heat produced from the fuel you use. Cheers.
One of the best on the net, we'll done you and a big thanks for sharing the results
philzambo Glad you enjoyed the journey mate cheers.
I agree philzombo, these vids are the best info for the rocket stoves.
Great design and build videos.
Always a pleasure seeing them.
floyd eccleston cheers floyd
Thanks again for your tutelage! I learned a lot over the...years?!? Time flies when you're having fun...or not, for that matter!
Sweet. Don"t loose the door. It is totally worth seeing the fire. even if you sacrifice some efficiency. Your stove is now (I think) the best on the Tube. Well Done Sir!
quincy wheeler Thankyou nice of you to say that.
The best. I have seen a few cast cores now in the running, but they haven't enjoyed the successes as Mr Ppotty has, as he understands secondary air.
Your refractory and perlite/vermiculite mix, I don't remember which you used, but I fail to see much difference between them, is the one I plan to use, though I plan to use Sonotube® as a mold for my horizontal to riser section.I have figured out how to make a spiral channel with an embeded steel tube in that spiral channel to bring air. Just attach to the tube, and let the material I make the channel with, wood, burn out, leaving the metal tube, which was attached to the wood in the recess.
I had thought to make the batch box casted, and want to try it in the future, but I have a metal fire box in need of a home, built in the same configuration as yours, top load, horizontal chimney, as part of a smoker.
Im impressed by the amount of work the man did to make this wonderfull heater
Great coming on fast when I'm on with a project it take over its great you show your hard gains findings thanks Paul
paulshawp Thanks Paul ...you not snowed in over there .
Wow! You're a Godsend. I was having the same problem. My insulated burn area gets too hot after about 2 hours and then my draft gets weaker and the burn chamber gets too hot. This is a problem because my system is a gravity fed pellet system. When the burn chamber gets too hot, the pellets gasify early and it's completely unhelpful. I got a couple of fires in my hopper and between your video and another, I realize that I need to remove the insulation around the burn chamber.
Jamal Johnson Hi Jamal glad my video could help you figure out your problems...did you build the heater yourself ? i remember trying2lhard was building his pellet feed with that problem in mind. Cheers.
*****
Yeah, I built it myself. I only have only 25 inches of vertical clearance in which to cram my ash tray, my horizontal burn chamber, my riser and 2 inches of insulation above my riser. This leaves me with a 14 inch riser. So my draw is meager and can't afford to suffer from that early gasification problem. I wonder if changing the diameter of the riser is gonna change the draw strength. Currently the riser tube is 4 x 4 inches (100x100 mil).
Anyway... I just dugout all of that insulation around the burn chamber. Test burning it right now.
You da man
Jamal Johnson Hey Jamal good luck with the changes..a bigger diameter riser would obviously move more gas through the system and have a stronger draw if you reduced its size at the entrance, like you say its fairly short in length but I think a 5 inch riser would improve things how much I cant answer. Cheers.
You are the man
Awesome! Your the rocket stove King. I just love that flame.
***** Thanks John i could watch the gasses burn for hours lol
Thank you for the speedy reply. I am going to put your idea into action this autumn and let you know how it goes. I will be in touch again when I begin. awesome videos and thanks for sharing. All the best
+Sony Droid Look forward to seeing what you come up with mate. cheers.
Gotta love these stoves! That one is a keeper!!
kbbacon thanks kev it is for sure.
I'm looking at my woodwarm stove right now which is great and pretty efficient and we use about 1/4 of what we'd burn on open fire but keep the house warm enough just with that. However seeing yours kicking out 300 cent on 3 little logs for a couple of hours knocks ours into the long grass! Slightly worrying with the varnish melting though, put something like yours in the living room and we'd burn the fuckiin house down! Brilliant vid series chap and a lot of food for thought. Thank you!
Hi there and thanks, and yes massive heat output on very little fuel, more importantly clean burning
I found that in my stove it is radiant heat comming from your door window and not convective heat. So I would leave your window great vid by the way ;)
Cheers
140 F is a low flue temperature (60C) I would not worry about it, you need some "rise" after leaving the chimney to carry the condensate you sometimes get away from the building.
Best stove I've seen. Well done ppotty1.
thanks again, its still going strong
You've got the sickness my friend, The Fire Bug Sickness lol. All kidding aside it's an awesome stove and I'll bet you get years of service out of it. Just like tryin2lhard I was wondering about that old stove autopsy though. I think building one like that would be more my speed, At least for my first one lol. (I'm not much of a welder yet) Thanks for sharing all your work and experiments with us.
ATB, Steve...
stevenk1965 Yes i got the fire bug for sure steve have had it since i was a kid, just put the post mortem up of the old stove afraid its RIP...Cheers.
Brilliant, brilliant, brilliant, well done mate! Having watched quite a few rocket stove videos, I've come to realise that yours is one of the best! Congrats! I think it's well thought and put together and very economical. To get so much heat from so little wood is amazing! With regards to the top plate, I would put a slab of thick cast iron. It would definitely not bulge. Crikey, I would even make the exchanger from cast iron, just imagine how much heat you can store in it! I've got a few questions for you - should you have the time to answer them - it would be much appreciated! So here is the story: I'm running a joinery business and renting this out building that I heat with a 23kW wood stove (no gas supply here!). I knew about rocket stoves before I bought it but my workshop consists of three individual rooms, so had to go for the boiler version. Given its power rating, I knew I would be burning wood by the barrow but since there are quite a few construction sites around that skip a lot of wood, I thought I would not run out of fuel - which I haven't anyway. Still, I am not very happy that I go through more than half a cubic metre of softwood a day. Even though I get it for free, it's still a waste, plus it takes time to cut it and load the stove every 15 mins or so! I would be spending about an hour a day doing only this - that's an hour longer at work. But don't get me wrong, the stove works beautifully even though it's o no-name Chinese made. The plumbing is simple and leak free, it chucks out serious heat, quickly heats up the water and all 6 big double panel radiators are kept at 70°C all day - cushty! Even so, watching your videos I had the thought of asking you this: do you have a solution for a boiler rocket stove? That would be a heat exchanger whose sides and back are the boiler (or only the back). Did you give it a thought until now? I can only imagine how efficient it would be if installed inside the house and supply hot water and heating for only a fraction of the cost a normal stove requires.... Cheers!
cinamaster Thanks mate, interesting story as my friend heats his woodwork shop the same as you from a similar stove with water heater and rads around the place, i know he uses tons of wood in a winter too and spends alot of time cutting stacking and loading it into the stove. I think he could fit a rocket stove alongside it and connect it into the existing flue for the days when the temp inside just needs a boost using only the rocket.
I have done some work on boilers in my earlier videos and intend to follow it up at some point and actually build a full working model which will look alot like this stove from the outside.
I also want to scale it down so it can be used indoors with the aim of getting it approved for residential use, (well thats the dream scenario) if not guys can build it for themself.
ruclips.net/video/FLcIrrHjdUM/видео.html this is the video that shows the basic idea with combined firebox and exchanger fitted with wrap around boiler the front of firebox would have a glass door. Cheers.
Nice job Loz. Bolt the top on and cut slots for the bolts so that it can expand rather than bowing.
***** Thanks Graham, good idea mate I can drill the holes much bigger thinking about it and fit a washer under the bolt head. Thanks for that.
***** Did you get the one for the house sorted Loz? Last time I looked in you were working on a big one.
Very well thought out, thanks for sharing your hard work.......
Master Lui-Gino Di Serio Many thanks.
Thank you ppotty1 for this excellent info. I intend on building one into a thermal mass possible underfoot in an earthen floor. I particularly like your findings regarding the slowing down of the draw or keeping the heat in the box longer. Have you considered adding some thermal mass inside the combustion chamber, between the cast riser and the exchanger. Maybe a pumice allowing for air to pass through but much slower.
Skill Billy thanks mate, I have seen volcanic rock used inside stoves to further clean the gasses and to add thermal mass its something i may try. Cheers.
OMG that is really hot!! You got it right again ppotty1. Very nice project! Anyway Happy New Year to all Stovie Guys.. Good Luck and most of all God Bless.
bobot021070 Thanks alot mate.
Just a thought about your comments about pre heating the primary air thats being fed by the ambient air in and around your stove within the envelope of your shed, cold air expands. Just like a hot air balloon as its heated it produces positive pressure which carries heat with it and if you fed your primary air directly from the outside the effect is no air is needed from the leaky drafty spots around your door and windows. Every modern stove built since 1970s have this ability and has become a better practice and procedure. I'm not being cheeky and admire the interest you share. Its just worth using the gains you have recieved with insulation and balance it without compromising the radiant properties a steel structure exhibits. Batch box rocket stoves are quick heat heat up but the also cool down quick. Try a highly insulated bell bench on that back wall with thick capping stones for thermal mass to help retain that lovely heat and perhaps you'll find you need to burn even less wood and that heat will be more even and last longer. Cheers
Hi Matt, yes the primary air is fed in from the outside on this stove and gets pre heated in its way into the firebox, but i never really wanted to build a permanent mass around the flue, as of now I am going to move the flue into another building attached to this one, this should provide all the heat I need for it, cheers
@@LozHarrop Forgive me if misread the lenght of the primary air feed tube, I assumed you hadn't extended the 2 feet of box pipe I saw as your feed tube to extend to the outside of the building. In all fairness the connection wasn't made clear in the video. Im also at odds with the idea feeding a combustion chamber with cold air because it expands vs protecting the point of combustion with the use of insulation which results in the highest possible temps and therefore results in the cleanest burn. My thought is your work up in the front end is excellent and I personally wouldn't change a thing. My comment about what you do on the back end past the riser wasnt fair either as i didnt concider the back wall being made of concrete. I live in a province within Canada that has extreme low temps in the north (-60c) and on the island portion we have the highest sustained winds on the planet. We wouldn't build a structure that hadn't had insulation (thermal break) and a completely sealed vapour barrier on the winter warm side. Our thermal mass is highly insulated and contained within the buildings envelope. Its hard for me as a British ex-pat living in the new world to make a suggestion back in the homeland where it's tradional to do things in a certain way. My interest is to soak up all the wonderful things you are doing and add my thoughts in order to reciprocate. Keep up the good work.
Nice job ppotty1, my guess is no autopsy on this one until 3 more winters have passed including this one, maybe longer. Thanks for sharing!
Bigwannas hopefull mate, but will have a spare riser standing by just in case.
Yup..No harm in that,cheers mate;-}
Impressive achievement, P! I've studied rockets for a long time, and built quite a few. I do all my heating and cooking with them now. But I've still learned a lot of useful insights from watching your videos. I'm building a rocket with radically-changed geometry right now (though with all the basic Aprovecho-derived construction/function principles still maintained), and your work here has given me lots of useful demonstration that what I have in mind will work fine. Many thanks! And great to hear that old accent of my childhood too, for a bonus. :)
Outstanding work. Tryin2hard could well be right: Best rocket on the net - or one of the few best. Cheers, RhG
Rhisiart Gwilym Hi RhG, Thanks for your comment I am happy that you found the video of value and hope you go on to making something that fits your needs. You still got the accent lol...cheers.
Great videos bud joy to watch! Just an Idea for your pre heat, can you use a pipe within a pipe. Outside being your inlet & exhaust being the middle thus take more heat out of you flue exit temp. Maybe insulate with another pipe around inlet/exit pipe with ceramic insulation in the gap. This also makes it fail room sealed so you could insulate your workshop and save the heat your producing. Keep up the good work!
Arron Potter Thanks for the comment Arron, I thought briefly of doing that around the bottom horizontal flue section but the fabrication put me off the idea, i think some movement through the exchanger would be good thats the hottest part of the system and fairly easy to fabricate and connect. Cheers.
I'm thinking of building a heat jacket around my stove and using a blower (off my other woodstove) and blowing the heat into my ductwork to heat the entire building. With that kind of heat produced, it needs to be routed where it's needed.
Painter D Good idea Painter
Great vid mate that is a fantastic stove for sure Love it just love it
Joe Bis Thanks again Joe. it is pretty awesome in use.
I really appreciate your work on these stoves as I hope to build an RS with water heater for my 50's bungalow in SE England so I feel your 'uk centric' research and experimentation invaluable. I have reasonable mig welding and fabrication skills although I have yet to even light let alone build a RS!
May I bother your for two quick questions pls? The first question is based on the premis that I am not sure if you have produced any research findings on water heating RS's.
1. If I were to install a ( copper or steel ?) water coil inside the heat exchanger, around a refractory riser, what proximity or touching, could the coil wind around the riser, having seen your risers glowing red.
2. When purchasing the sheet steel do you worry about the grade? Prices vary for 8x4 sheets from £130 to £350.
Many thanks from Duncan Southend on Sea
Hi Duncan, The inside does glow red but the outside is much colder, you could have the coil touching the outside of the riser without any problem, I have always used cheap mild steel sheet sometimes scrap when i can get it. Cheers.
I think I'll also make my riser tank to be bolted on at the bottom so be able to make the entire stove in pieces, for ease of installation and inspection. Also line the firebox with fire brick or pour it with refractory cement, the same as the riser. My idea is to make it big enough to get a long burn time and better control of the temperature, so I can turn it down (I don't need 1000 degrees running temp) The pellet feed I have fabricated and works exceptionally well, so I'll also have that option when the time comes. I found the heat from the pellet burner are able to be controlled for a more even heat. Thanks for all the info!!
Painter D Good to hear the pellet feeder is working well, its more than well worth the small effort to make these stoves modular, its just so easy to then take things apart to inspect repair or replace them. My old welded up stove has to be now cut up to take it apart, that process will destroy everything. Cheers.
***** Just wondering if there is any noticeable air flow through the square tube you installed in the back of the heat exchanger?
MrGordy61 nothing you can see or hear mate but the air is moving through fine feeding the stove
Nice report, really like your stove. Was thinking on doing the same as for insulating a future project\stove. If your redoing your topplate and want to really pre-heat your air inlet, why not constructing a second chamber above the reisertube and use that blast to heat your air, guide it inside your heatexchanger, into the firebox. You cant het hotter air then that. Make the second Chamber wide, so the air can slowly heat up. You wont lose that heat as you reuse it inside the heat exchanger. Maybe you have a faster start of a clean burn. Hope this helps. Greetz
Kim Lesage Hi Kim, and thanks. Problem with pre heating air is once you heat it as you know it gets much lighter and just wants to rise, it will have a negative effect trying to naturally force very hot air down into the firebox, my thoughts are that the air needs to be fed in on a rising or at least level path, it would work that way if a small fan was fitted to push or pull the air down though. I would try and feed the air through the exchanger on some kind of baffle or similar to the copper sec air feed on this but using 2 much larger tubes to feed to each side of the firebox. Cheers.
***** hey, been thinking about your respons for all day now :-)
Your right, hot air wants to rise, but wont the hotter air from the risertube suck in the less hotter air from this preheating section? It can slow down, but you've narrowed the inlet before. Maybe it the stove will be able to adjust its self? I going to try it in my future project, somewhere in 2015. Cheers
please give it a try mate and see what think, hopefully my thinking might be wrong and if so its a new idea that will be worth putting to use...Cheers.
Just watched this series of videos on the new stove, as well as the autopsy of the old one. Brilliant work. My build was delayed until January due to some uncontrollable issues, however I'm kind of glad it did; now I've got some new design parameters to throw in. I've got some air preheating ideas to work on; I'll let you know how it goes.
J.D. Ray Nice one J D sometimes pays to wait a while, I know someone will no doubt improve on the things I have done on this stove once they get to work on a build, main reason I put out my builds as we all get something back in improvements later down the line. cheers and look forward to seeing what you come up with.
Thank You very much for sharing. Useful tips and observations :)
MrKardukas thankyou
Brilliant, I've subscribed.
Quite a bit of work, all told, but seems well worth it. Building a 2nd one would likely be quicker .
Finarfin Thankyou, yes once you figure the first one out the next is much easier and faster.
+utubeaccess7 Thanks for the comment bringing the primary air directly through the exchanger into the sides of the firebox would really improve the pre heating and could be done really easy. Cheers.
I think you built an awsome rocket stove. You put your thoughts in the design, changed them when you weren't satisfied with it and the end result is a killer. I was wondering if instead of wood the rocket stove could also run on coal briquettes? Have you ever tried that? Coal briquettes burn very slowly and as far as I know they are cheap. A disadvantage is that they produce more ashes than wood, but perhaps the rocket stove's high temperature also burns coal briquettes more efficiently.
I have never tried coal Michiel but i know it will burn on rocket stove how clean im not sure
Your experience and craftsmanship is much appreciated, thanks for sharing. I am getting ready to build a stove for my 16x20 canvas wall tent.
I've decided to cast the riser and fire box with the same mix as you have done.
Obviously weight will be more of a factor for me but the trade of will be worth it.
One thing I'm considering is only casting the riser , half as tall than use stainless steel the rest of the way.
The dimensions I am thinking are:
5" diameter riser, 34" tall
Fire box : 8"x10"x12"
Heat exchanger: 18"x18"x36"
I'm guessing on these, I haven't been able to find any formula , it looks like you are about 61/2 inches in diameter on your riser, can't tell on your flu,
Any chance you can share some of the dimensions you have dialed in?
Thanks so much.
Rodney Ficklin Hi Rodney and thanks, The dimensions you give sound ok to me and should be good. I totally forgot to put the dimensions of this stove on the end of the video sorry. Will sort it out and put another short vid up giving all the dimensions and anything I would change to improve this. Cheers.
greetings Potty. thank you for sharing your design. the metal fabrication was great but the vortex draw on the cast riser was awesome!! your design is an inspiration, and a confirmation of ideas about a cast riser.
What are your thoughts on adding a wet heat exchanger to a stove like this to heat water for underfloor heating / radiators / bathrooms?
+Sony Droid Cheers, This stove would take a water jacket or a coiled pipe set up to heat water, if coiled around the outside of the riser it wouldn't effect the temps inside due to the riser thickness, a water jacket on the top or sides of the exchanger would equally work well, Ideally you would have a big water tank as the heat store and draw the heat off that through the pipe work, unless you dont mind tending the fire to generate the heat as you need it.
Thank you for sharing your whole process! I have been doing my research and was thinking of casting a section as you have, so it's good to have gained that experience here in my pajamas this morning! : ). Just a thought regarding the primary and secondary preheat. So a preheat through a passage bonded to the exchanger as you have proposed . Also, make that a dual passage, one for the primary and one for the secondary . It seems to be of benefit to have the secondary air as hot as possible as well . rocketstove.nl has his "s-tube" heater . Looking at that I'm a bit leary of putting any metal in the path of the burn/ blast but its a good example to get the thought process going. Where to get the most heat ? Well you had that problem with the lid turning blue, that might be a good spot to pass the air , cooling the lid and getting that combustion air as hot as. A bit of a puzzle with passage and gasketing to retain the lids function as a lid. So, that's my thoughts . thanks again, great videos, great design. When i go to make my stove I will have derived a good advance in experience from this.
Fantastic videos! Could you summarise, please, all the advantages of the secondary air intake? It's a lot of work to put one in if I made one of these and ,being a novice, I don't understand the advantages of secondary air. I understand everything else. I dare say you mention it on one of your earlier videos but I must have missed it if you did. Apologies and thanks again for the brilliant films.
jazborocketman Hi There and thanks, Sec air simply puts extra oxygen into the riser which burns any gasses that remain after combustion in the firebox, on this stove as I shut down the primary air supply to the firebox, when the firebox is hot enough to gas the timber, the sec air supply can be fed in to ignite any gasses inside the riser without passing more air over the timber in the firebox. Hope that explains it. Cheers.
Great. Thanks for that. Just what I need to know. I'm going to make a stove a bit like yours but I'm using a pumice flue liner and other bits made by Isokern instead of the cast riser. I'll let you know how I get on.
jazborocketman Yes let us know how it goes mate.
Well, what can one say? Brilliant design and brilliant execution - just really well thought out from stem to stern. For me I'd say the most critical element of your improved design is the modularization utilizing the refractory cement chamber and flue constructed as consumable item. Conceptually there are breakthroughs increasing efficiency with regards to pre-heating, secondary air injection and it's attendant issues (location, rising, etc), entraining heat in the fuel box to promote gasification, etc; but the modularization is what allows the design to become practical as the whole stove doesn't become consumable item ;-）
I'm curious to know about your adding pearlite to the refractory cement as it's primary purpose is to insulate, but in that portion of the burn cycle I don't see the need to insulate the column. Why not just cast 100% refractory cement whilst adding a bit of glass for structure and tensile strength?
***** Hi Scott, thanks for the comments, I remember being unable to reply to your comment maybe due to your google privacy settings, But to answer your question I added perlite as an insulator to try and keep some heat in the riser and so the riser would heat up faster, solid refractory soaks up and robs heat where as a lighter refractory does the opposite, the amount I added probably did not make a huge difference but im sure it had some effect, since casting this riser I have found a much better alternative and will be casting another riser shortly to try it out. Cheers.
brilliant ,need to get off my lazy arse clean out garage try make some pigeon boxes will be using calor gas heater .would love your set up but my place to small really enjoy your channel. cheers
stevie 1 Go to it stevie lol
22:15 Ideal conditions for perfect toasted marshmallows.
Thinking of putting a rise on top of my wood stove . Controlling the air flow with the door . Tank over too and long pipe for the chimney. Your thoughts
hi and well done for the series on this project
my question is about the riser
how is it holding up and would you change it for a more insulation type material to hold in the heat
also have you had any thoughts on a front window of the firebox?
cheers mate
+dusty saunders Hi Dusty, The riser is fine mate still as good as when i fitted it, more insulation would be good but this dense kind also has its benefits giving off stored heat when the fire has gone out.... just doing some mods on the stove at the moment, I wont be having a door on the front just easier if its on the top. Cheers.
Good job mate
Jason Bentley thanks bud.
Hi, Great videos with a lot of thought behind them. You seem to have worked out that the hotter the incoming air, the faster the gasification so the more efficient the burn. I noticed that you lined the firebox and also the outside. Would you not increase the heat of the incoming air be removing the insulation from the inside of the firebox and maybe putting fins on the outside where the air travels up and enters the top. I know it might seem that this will reduce the heat inside the firebox but as I see it, you are lowering the burn temperature by introducing air that is cooler (I know its very hot) but cooler than it could be anyway. think you might get an overall gain as the incoming air will heat faster on the large surface area of the outside of the firebox. By the time it gets to the fire it should be closer to the fire temperature. My thinking is similar to how a TLUD heats the incoming air on the outside of the internal firebox. If this works you might have to make the walls of the firebox sacrificial though. You do great work, Thanks.
+Boatman's Bolt Hi There, and thanks, I see your reasoning and I had the same conflict when i was working on this. I had a couple of test burns before lining the firebox to see how it all performed but believe me when i lined the firebox the difference was obvious in the gassing. Despite the lining the heat still gets through to the walls of the firebox and is transferred into the incoming air and it works really well, as you said a stand alone metal lining would not last long. The lining has the added effect of storing heat inside the firebox were steel would cool down very quickly one the fuel burns down. So the lining is not really a compromise it actually has benefits. Cheers.
Hi again, I'm still at the design stage an wondering about a few things, I would really appreciate your input:
Primarily the same basic design as yours but with a cast firebox with the primary air, coming through ducts or holes cast into the bottom of the heat exchanger/burn tube casting, and feeding the top of the firebox. Do you think this will produce enough preheating of the primary air to get good gasification like in your design. I am also wondering if the secondary air inlet into the bottom of the flue should be placed at the tip of the narrowing entrance to the flue so that it acts like a venturi. I thinking it might suck more or speed the incoming air and could maybe be jetted to improve the vortex and mixing.
I'm thinking of using thick wall cardboard tubes as the mould for the riser and mainly strong cardboard for constructing the rest of the mould (it might need waterproofing) so I can just burn it out, once it has set. This would allow complicated shapes to be easily and cheaply constructed. Your views would be greatly appreciated. I think you have one of the best stove designs on the net and thank you for sharing it.
Hi Cant really comment on how hot your primary air will get if placed as you say, where i to re-do mine I would maybe run copper tubes through the exchanger or some kind of ducting to get max heat into the air i know i could really improve mine if i tried and had known how much the pre heating improves the output of the stove. I tried several places for the sec air to enter and this was the one that worked the best for me but different designs may respond better if the air entrance is somewhere else, you just gotta try things out as all rockets are different in some respects, the cardboard tube idea is sound and can be burned out later easily, cheers.
Congraats! And Thank you so much for the detail explanation on your rocket stove!
I have a dumb question, though. What makes the flues go inside the riser instead of coming back on the fire boxx? I am trying to adapt your project into a rocket stove cooker/oven to be on a kitchen. I woulldnt wat to have smoke coming back through the firebox, and the test I have done showed that the fire was beeing feb by the riser and burning backwards! Thanx again!
Mauricio, Brasil
+Maurício Möller de Oliveira Hi there, if the fire is burning out of the firebox then either the firebox is too big for the riser to deal with or there is not enough gap over the top of the riser which wont allow the gasses to escape fast enough. cheers.
+ppotty1 OK thank you!
+ppotty1 OK thank you!
maybe double up the glass with a quarter inch between them? great work on the cast riser, would you cast the inner fire box as well?
I was thinking the same thing - two panes of glass, (I believe shooting your IR temp sensor at glass will give you the glass temp not what is behind it)
Great idea on casting the fire box liner!
Truly love your stove videos, ppotty1, well done indeed!
Brian Junk Thanks Brian,
Candoract cheers...yes I would now.
Hi,
watched all the videos and thing they are brilliant. My only question is how long do you think the steel will last?
Thank you,
laura taylor Hi There, and thanks, now the firebox is insulated and the steel protected form the fire I cant see this stove degrading at all, I think the first thing to go will be the flue which is very thin steel. After two months of using this stove it still remains as good as the day I first lit it so I think it will outlive me.
In regards to preheating the air, a tortuous path with lots of fins? I like the idea of having it flow around the heat exchanger. But, how can you create a flow of that heated air into the room?
+agape713 I guess a fan would move the air around the space faster or the hot air could be ducted around the room too.
Is there a way to create a fan that turns so easily that the rising heat turns the blades?
It would be self propelled. The rising heat starts the blades turning, which then causes a vacuum which causes more heat to move towards the fan which causes the fan to continue to turn. Self perpetuating? Is that the word? For instance, on the older jet engines, once it started, the exhaust hit fan blades connected to an (axis - rod) that turned the turbine in the front. So the exhaust then turned the turbine. That's not the whole system but you get my meaning?
Ever considered wrapping copper pipe around the exchanger to heat water tanks to act as a heat 'battery'?
Brian Junk yes discussed that mate, dont need it on this stove would be good on a building with more rooms.
have a look at peter van den bergs rocket heaters ,there is some craisy heating going over there plans can be found on face book rocket stove /rocket mass heaters
I would like to build a similar stove to heat my cabin but I'd also like to see the flames when sitting around the fire. Do you think it would create any issues if the glass was on the front instead of the top? Is there a limit as to how large the firebox can be? Ideally I would like to achieve an overnight burn as well.
Phil Tyers Door would work fine on the front with no problems I can think of, you could in theory make the firebox very big however if its too big it will overwhelm the gasses the riser can take so it will burn dirty then vent out flames when you open the door, i think the firebox on this stove could easily be 4 inch wider and 4 inch higher without any issues, you could make a large light weight temp test box just to find out how big you could go, do some test burns and if too big and fire gets out of control or stalls due to lack of air or riser flow place firebrick inside to reduce the internal size and test again, keep adding filler until you find the ideal size that the riser can cope with. Cheers.
great RS video, learned a lot!
+John Dunn Glad to be of help...cheers
Heat exchanger :
hot air going up,
if you inclinate blades you should augment contact metal/air, so increase exchange.
fred san yes I see what you mean fred many thanks .
Cooling system in water are 45° blades I've seen (with other metal plate on - protect wooden table). Very good RS concept'
fred san Thankyou fred.
*****
Magnets,
dfferents smalls steels pieces,
play test on hot stove
(caution magnet doesnt like hot).
Good end of year.
Hi there,
I'm just catching up on your rocket stove videos, I like both of your builds very much. But why aren't you using the same exhaust system on your second build. I think it's quite brilliant to use a very long exhaust so more heat can be transfered to your workshop. Regards, Alex
Hi There I dont really need the heat output from the flue with this stove but also the new flue was scrap and was not long enough to replace the old one in length, the stove vents much better with this too.
Has the flu pipe cooled down now that you have insulated the outsides??? Just wondering if your losing much heat up through the flu? Thank you for sharing your knowledge with us : )
scramblendan No problem, the flue temps are pretty much the same as the last rocket stove actually, I have since taken the temp readings from the horizontal flues behind the bench and they match what the old stove was putting out burning flat out. This burns slower but achieves the same temps as the old one which is a big improvement.The radiated and rising heat from the exchanger has caused the increase in temps to the vertical flue above it. Cheers.
Instead of insulating the firebox what do you think to a disposable 10g inner liner? It would get red hot in no time to aid gasification and after a few weeks just throw it away when it distorts and fails.
not sure what 10g is Shawn
10 gauge steel its equivalent to 3.25mm thick, I'm still in old money :)
How critical is the distance between the top of the riser and the bottom of the top plate?
Hi Dan Same answer here as your other question, you need around 3 inches gap over the riser tube or you can choke it up its better to have more gap for the gasses to escape
ppotty, seeing you do the casting, it looks really easy and simple. Then seeing that you had to line the inside of the fire box, what do you think about casting the fire box, (four sides and bottom) then just using thinner metal to make the air passages? what do you think?
Rick Taron Hi Rick yes you could probably do that and all would be fine, when you look at my old firebox the outer 2mm steel on the sides has suffered no damage because it was protected just by that thin piece on the inside. I would say 3mm would be perfect, that is what i have used on my new exchanger and the outer casing of my new firebox. cheers.
***** Happy new year! I am working on a stove build that will heat my storage tank of hot water. 1000 gal. so, I think will make something similar to your heat exchanger but just add about 80 ft. or so of 3/4" soft copper tubing, circling the riser tube. I will draw something up to share with you. thanks again!
Rick Taron happy new year rick, you could circle the copper around the inside walls of the exchanger weld some lugs on for it to sit on, you would get much more copper inside the exchanger and it would still get very hot, this would allow you to change/swap the riser easily if it needed replacing. Cheers.
***** dl.dropboxusercontent.com/u/16468811/wood%20water%20heater.pdf
here is what I was first thinking about using two 55 gal drums for the heat exchanger with insulation all around. but seeing the trouble you had with sealing between the burn chamber , round to square looks even harder. I'm thinking maybe a square heat exchanger might be easier. with just one shared wall between the burn box and the exchanger. back to the drawing board.
Good job! one of the better designs! What do you think of a total stove made of ceramic?
ceramics would be great for all the hot bits in contact with the fire but you want steel for the exchanger to extract the heat into the room.
Steel warps with heat I don't agree it is most efficient. When I use the term ceramic I am referring to the material you are using to construct the inner section which is a concrete fire mix. Round would be better than square as it would allow the heat to distribute out evenly. Possibly using steel to encase the ceramic could be a possibly. Over all are you happy with the performance of the stove and the design meaning a rocket stove? I find the Russian stove a unique design as well.
Are you in the UK?
The exchanger body never gets hot enough to suffer from heat damage, just the top tends to distort from the heat directly over the riser, but yes ceramic riser and firebox etc all good for longevity. The stove is great in operation and performance my shop has been warmer than the house this week and im hardly burning a barrow full of wood a week. Yes im in the UK north west.
Thanks for the review. On my square heat exchanger, instead of the angle iron fins, I went ahead and cut slits through the exchanger then welded in 1/8" steel strips, 2" to the inside and 3" to the outside. The fins on the outside are shrouded with an aluminum panel open at the bottom and top for convection. Question: What is the diameter of your flue pipe?
Al Ryzy Thanks Al the flue is about 6.5 inch outside measurement, it came from a grain silo very thin steel. Cheers.
***** LOL at myself. Been using 4", probably why the draft is poor at WOT, otherwise it's OK. I'll open mine up to 6". Hey, I noticed you're wearing the same hat as last year. Want one from the states?
Al Ryzy Hey thats a nice offer mate thankyou, i might need another soon in case I set fire to my head lighting the stove ;-)
Do you think fire bricks on the underside of the top plate (directly above your cast riser tube) would be helpful in preventing the warping?
Norman Kellison Yes they would but a steel plate is easier to fit, I intend to fix a piece of glass in the top directly above the riser to see what is happening in there which will be interesting seeing the effect of the sec air and the gassing stage.
I will have to see that video! That'd be something neat to see!
Awesome work. Just amazing. So many youtubers claiming to invent things they didn't, but you really made a better rocket stove. I do feel a little insulted every time you say "fellas". I'm sure most of your viewers are guys, but you really make the assumption that you have no female fans and you soooo do.
hey bud, i was just wondering what size of workshop your heating?
James Stoddart its roughly 25x25x8 ft sloping down to 7ft James single brick flat roof.
No not bad but went up by Rimington to granddaughters I laws farm about 3inch but it's on.
Tops near Pendle hill barley end.
paulshawp Im sure we will get some at some point Paul.
My thoughts on which way your vortex should go in your location if you fill your bathtub with water and start letting it drain if you notice which way the water drains! for example the water will turn a specific way as with the earth is turning I assume the fire vortex would turn in the same way this advantage it will create a natural turn of the vortex. if a person would be in Australia the vortex would be turning in the opposite direction. Do you have a idea of what I am trying to communicate to you? would this make sense!
Yes know what you mean Marc, the effect is so weak it makes zero difference to whichever way you spin the vortex. Cheers
you would have to agree if it turns naturally one way with the law of gravity if you send it the opposite way it would be fighting itself constantly. It would be more efficient turning the rite way. It would be more efficient this way. What exactly does cheers mean? Here when we use cheers usually two would raise glasses and say cheers It is a way to say I agree with you. In what context do Brits use it?
just means good cheer or good health or thanks
Why not put a thick piece of Soapstone on top it holds the heat longer an will never warp
Sorry about the strike through! I don't know exactly how I manage to do that.....
Hey ppotty1, Thanks for the vidoes! After watching yours I was checking out some videos over at T2H Instructionals. He mentions in a video that he uses stainless as a heat riser and has never had one degrade. I have seen elsewhere that stainless will degrade. I was planning to do a cast refractory core similar to your build you have shared with us here. Can you speak a bit to the reasons you ended up doing a cast riser and what some of the pros or cons may be? Thanks in advance!
+Wesley Aycock You may know there are different grades of stainless some being more suitable for risers than others, no matter the grade though if you put very high temps onto it for long periods it will degrade eventually. Ive always wanted to try a cast riser because i always used steel in the past im pleased with it and it has suffered no damage in the last year. pros are it holds alot of heat which goes into the exchanger when the fire is out and once lit and heated the stove draught's better, only drawback is it takes time to build and longer to heat up but as said the stored heat you get back anyway. costs of stainless and casting are roughly the same. I prefer cast over stainless for this type of stove. Cheers.
+ppotty1 Great! Thank you for the input. I will continue onward with my casting attempt. I'm planning to use a refractory cement called Secar 71 mixed with perlite.
BRILL & ALL THE COMMENTS.
How big of space would this heat
joe boss once up to temp around 600-800 feet of floor space but also depends on type of building, roof and insulation etc.
Thanks for the reply. I love your work I can watch rocket heater videos for hours and your is one of the best. I need one to heat my house its about 1100sf but holds temp pretty good I use a kings wood circulator works good just uses a lot of wood.
Can you burn sawdust in the firebox
yes i have done, did a video on that, it does tend to deposit ash in the exchanger though as the bits of sawdust get sucked in
@@LozHarrop do you have to keep exhaust pipe from stove rising ,you mentioned in on of your videos that your flexi pipe was 6inch dia and 4m long would you get away with 4inch and 6m long ,as I want to run through a heat sinc to dry timber,if I used sawdust would the ash build up quickly or would I get away with cleaning once a month through a removable plate at bottom of heat exchanger,thanks for quick response and greatly appreciate you sharing your knowledge. Charlie
@@charliecass6717 you could run it dead flat but the condensation inside the flue would just lie in there, i was given a new roll of 4 inch ss flue but its just too small for the size of the riser i have, pretty sure it would get choked up on my stove, if i had a 4 inch riser i would give it a try though. However a 4 inch riser would reduce the size of the firebox you could use. Yes have an access plate on the exchanger to suck out the ash every few months and it would be fine, good idea to have one or have access to the bottom of the flue as it may also start to build up in there.
@@LozHarrop Thanks loz
Ppotty1... Have you ever tried a cast iron pipe as the inner liner of a riser? I have one available to me and was wondering if you (or anyone else out there) might have had an experience... good or bad... by using a cast iron pipe surrounded by insulation as the riser.
Richard Workman Hi Richard, I suppose it would last longer than steel, but other than that I have never used it. Cheers.
***** Thanks... Since I have a length of 4" cast-iron pipe readily available, I will likely 'putz' around with using it as the inner liner of a smaller-scaled heater than your own and let you know the results.
Hey ppotty1, I love your stove, and all of the thought you've put into it. The air-preheating system is ingenious. I am very interested in building my own and have a number of designs floating around in my head. Every day, I peek in an industrial dumpster on my way to my car, and today the gods have smiled on me, and deposited one of these - www.bloklandnonferro.nl/en/cowl_silencer.html - a "cowl silencer". Mine is made by Phillips & Temro. I was wondering if you'd ever seen such a thing. It seems like it would be an ideal component for a rocket stove. I'm thinking an insulated heat riser could just be made that would fit up the central sleeve, and the vortex would continue throughout the spiral silencer, and the internal spiral surface area should be pretty effective at sucking the heat from the exhaust. What do you think? The design does not lend itself to effectively preheating the intake air like yours, but it seems pretty promising.
Lastly, if the thing has insulative steel wool stuff in there, would I have to get it out? I'm certainly not the welder you are, and would likely do more damage than good.
Anyways, just love to hear your thoughts.
A stove without a window is a worthless stove.
FishZilla :D the same as a chocolate fire guard.
For the life of me, I can‘t see why you keep insulating everything. The whole idea IS for heat "to escape" to actually heat the room. Pretty soon, all the heat will be forced up the flue.
Your concept is great.....but you are overboard on the outer insulation, in my humble opinion.
Waiting for next video.
22justus24U yes your right dont know what i was thinking about using it all. Thanks for the wisdom,
You're welcomed!! I really like your heater. I think you put a lot of forethought into it. It is one serious heater, in my opinion. Wish I could get one like it. I know with the time and material, it would probably be out of my budget. I'll keep watching to see how you do with it.
22justus24U Don't get mad, I'll try to be nice. But you know what sarcasm is don't you?
If you re-watch the videos he explains pretty well why he's insulating the fire box so well. We want to keep as much heat in the fire box as possible to insure a complete burn of the fuel, then remove that heat with the heat exchanger as the hot gas's pass through it. Unburnt fuel will condense in the exchanger and chimney, wasting fuel and forming creosote buildup which is a fire hazard. If you do a little research on outdoor wood boilers you'll find that many can burn 12 cords of wood or more in a season. Much of that is because heat is extracted from the still burning flame, that cooling effectively extinguishes the flame and the rest of the unburnt fuel goes out the stack as smoke. One guy lined the bottom half of his outdoor boiler with fire brick and a cement board across the top of that. He got the same amount of heat out of it but only burnt 1/2 the wood he did before.
Now that makes sense to me. Insulate away....!!!