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rocket mass heaters

Anyone have success using metals inside their rocket stoves?

John McDoodle

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posted 8 years ago

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I was discussing "using metal in the burn chamber and heat riser" and I was told to start a new thread because I wasn't having failures? I still want to discuss the topic of using metal and I want to know if anyone has any sort of long term success with metal, stainless, or ceramic coated mild steel, like myself...?

Maybe we can discuss our success stories here, or maybe you want to share your findings, or maybe you just enjoy prototyping with outdoor cook stoves.

Personally I have burned my first rocket hybrid experimental stove for over 50 documented test hours of intense burning, and my stove is in great condition thus far, however my internal mass and stainless hi temp duo-therm anti-corrosion liners keep the steel surfaces at a regulated operational temperature.

So what's your metal rocket story? My rocket and tests are documented, and soon i will post photos of my internals to show the condition of the insides of my clean burning rocket hybrid, so keep an eye out for that coming soon also.

positively optimistic 🙂 https://www.youtube.com/@613Builds

Steve Harvey

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posted 8 years ago

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There is a guy on youtube building a batch rocket out of metal and refractory. His name on the tube is 70kirkster. His videos are really well documented. I believe his build is very recent so you could follow his videos and see if it will last. His stoves use the thickest metal I have seen on a rocket stove.

Satamax Antone

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Well, it's a cyclonic type. Not realy a batch per se. I notice in one of his video, that he already has added firebricks to the bottom.

His heat riser is metal, but surounded by something? Refractory? Insulating or not??? Notice the darker spots in the bottom of the heat riser's metal, around the 12 minute mark? Buckling?

He's running with no door, so with excess air, which cools things down. Some smoke comes out of the heat riser. And without door, he's got a fair smokeback problem. In the dimentia and proportia departement, his port is realy big, which doesn't induce turbulence like the "port" does on Peter's ones. No Peter channel neither. And his heat riser seems short.

For example, the port in the batch as i know it, is prety much like a case example of perforated plate or "sharp orifice" , seen in fluid mechanics.

It's badly filmed, but you can spot the similarities i think. And understand the advantages of using such a way of building, to mix the gases.

This all is just details you might not have noticed at first.

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

Satamax Antone

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Another thing i didn't pay attention to, you can see smoke in his heat riser around that 13 minute mark too.

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

F Styles

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very poor stove design in the video and you cant even call it a rocket stove.

John with all do respect my friend i love your do it attitude and your drive to seek creative ways to do things but you must understand you can only call a rocket stove a rocket stove if it produces rocket temperatures. The whole idea and concept around building a rocket stove is to release as close to 100% of the stored energy in the wood by cracking it all with heat and the reason most metals wont do it. stainless steel of the correct type will get you a sub par smokeless burn but that barely reaches higher than a conventional wood stove. The majority of and reason Rocket stove makers make their rocket stove with refractory material is to reach stainless steel forging temperatures.... yes temperatures that melt stainless steel.

just because you get a smokeless burn and your unit looks like a rocket stove does not put it in the proper rocket stove category and barely sits in the sub par category.

John you have not done anything or proved anything new. youre operating your stove within the stainless steel operating temperatures and it will run til the cows come home until you insulate the heat riser properly and then you will have molten pile of flaming hazard. its almost as if you want acceptance in to the rocket stove of breaking rules hall of fame when you have not broken any laws or operating temperatures. you have good ideas and have a knack at pushing metals to their max operating temperatures but thats all this system is doing.

metal can be used for a proper rocket stove but steel is not it.

Rocket Mag evolution timeline: http://www.permies.com/t/52316/rocket-stoves/Rocket-stove-heats-water-pics

Rocket Mag Thread: http://www.permies.com/t/54074/rocket-stoves/Rocket-Mag-heater-Rocket-Mag

John McDoodle

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I made a 20 minute long video on an internal inspection of my stove today. It's going to take a longgg time to upload to YouTube I suspect, but I will upload it regardless perhaps tomorrow. It shows the inside of my stove and the condition of all the components including the stainless liners and the steel structure. Look for the video perhaps tomorrow guys.

I still have not had time to check those YouTube videos yet Satamax , but I will shortly. I already know your opinion on steel FStyles lol

positively optimistic 🙂 https://www.youtube.com/@613Builds

F Styles

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John... its not MY opinion period.
Fact: steel has an operating temperature and if you stay below it it will function as made.
you have broke no rules or laws.
i have never said that anyone can or cant do anything or even use steel in their rocket stove... I use steel in my rocket stove, its just not in a high temp area.

Remember the goal of a rocket stove=crack and release as close to 100% of the wood energy and use as much as you can. if i am not using most of the wood energy inside each pound of wood i am not only wasting my time, energy but also wasting natures resources.

1000F is not reaching that goal and is comparable to some conventional wood stoves. you may call that a rocket stove but it is sub par performance for one at the most.

those facts in no way are meant to disrespect your designing and building capabilities but are to inform new folks that a 1000F internal temp system is sub par and a better system can be built and still will not get you the proper performance of a rocket stove should do.

Rocket Mag evolution timeline: http://www.permies.com/t/52316/rocket-stoves/Rocket-stove-heats-water-pics

Rocket Mag Thread: http://www.permies.com/t/54074/rocket-stoves/Rocket-Mag-heater-Rocket-Mag

John McDoodle

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My hybrid "goal" was to step away from propane reliance and to be able to cook, and economy. I have happily achieved all my goals. Internal flame temps of any open flame are 1000C not 1000F. But my SURFACES are well below 1000F.
I know my system sucks and I'm doing nothing new to you. I already know your opinion I've heard it multiple times. But this is not about me or my rocket, or your opinion so
back to topic,
Have you guys had any success using metal in your rockets?

positively optimistic 🙂 https://www.youtube.com/@613Builds

John McDoodle

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I found this today on the negativity thread, where they ask specifically only to see failures, and when you post positive outcomes, they delete it, completely biased but they asked me to start a positive thread so here it is. Post your metal stoves here, longevity, photos videos success stories etc.

Here is A post I found today in the metal failure thread, im surprised they haven't deleted it yet , because min blowingly , satamax asked to see only failures, and thus do delete the positive stories, ask me how I know ... Lol.
Post by: Peter van den Berg, volunteer
on Mar 10, 2016 03:19:53 Mark post as helpful Quote
In discussions whether steel rocket stoves will fail or not, people tend to forget the temperature isn't the only factor in the equasion. At least one other is very important: the presence of oxygen or the absence of it. Obviously, steel is unable to corrode without it. Maybe there's also another factor in play as far as the steel doesn't get to melting temps, namely low carbon environment. But for simplicity's sake, try to deal with temperature and oxygen as the main issues. Keeping the temps below a certain threshold is one way to prevent rapid corrosion and keeping oxygen away is another. Steel won't be destroyed by corrosion up to melting point without the reacting agent, oxygen. For example, in the middle of a flame there is very little of the stuff, it's all unburned volatiles.

What I want to make clear is this: don't focus too much on temperature, there're other reasons why steel could survive provided it is done in a proper way. Too low oxygen as a whole isn't good because it will create a dirty burn. Too much air to keep the material below a certain threshold will cool down the fire and lowers the efficiency coupled to a dirty burn again.

And frankly, I don't believe in building an excellent burning appliance just by sheer accident.

positively optimistic 🙂 https://www.youtube.com/@613Builds

Satamax Antone

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John, you don't understand what Peter is saying.

Making a working metal rocket could theoreticaly be done, providing you have nearly zero excess oxygen. With the variations of gasification of the fuel, it either ends up in a sooty burn, if there's excess fuel being released. And it ends up with a hot burn, with excess air, if not enough fuel is released. Which will corrode the metal heat riser. You could avoid the temps at which the metal corrodes, but then you are not burning hot enough to have efficient combustion, and get soot again.

Which means it is on the verge of impossible. As I said before, you are welcome to prove me wrong, but the rule of the game is, you need to insulate the burn tunnel and heat riser. Otherwise it is not a rocket stove.

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

John McDoodle

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he said there are multiple "other reasons why steel COULD survive" and more suggestive positivity.

i suggest anti corrosive stainless or titanium over steel anyday- if using metal

positively optimistic 🙂 https://www.youtube.com/@613Builds

Satamax Antone

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John, i'm not negative. It is just on the verge of nearly impossible. I would love working with metal, it's so easy compared to laying bricks, for me. But i have been there, done that a few times, and so far nothing metallic has survived. Even my refractory clay tubing gets an horendous beating in the 9 incher i have in the workshop.

Try a "by the book" rocket, and you will understand that you are wasting your time with ideas of internal mass and the like.

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

John McDoodle

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I'm currently building one with all cast core, which has no metal internally, but my original rocket has metal that is fine , did I achieve the impossible? According to what you are saying I have achieved something nearly impossible, but according to Peter, there are multiple ways metals could work, so I have not achieved the impossible. Myself I know it's not impossible because FStyles has a steel propane tank exactly where his combustion occurs, and many people sell metal rockets with 3+yr warrantees and also, I've done it first hand. It's just HOW you do it that matters.

I suck my stove sucks and that's what haters gonna say, I already know ,
but I'm gonna continue to be warm and happy eating rocket baked apple pies and pizzas with super efficiency, and nobody's opinion will stop my heat or my happiness with or without steel, with or without others opinions, with gleeful joy of personal achievement satisfaction of testing my unit all winter with only success and fun invocation all along the way, so after you keep repeating how metal is doomed, and I acknowledge your opinion, then we can get righ back
On topic:
Anyone else have success using metals?

positively optimistic 🙂 https://www.youtube.com/@613Builds

F Styles

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John McDoodle wrote:I'm currently building one with all cast core, which has no metal internally, but my original rocket has metal that is fine , did I achieve the impossible? According to what you are saying I have achieved something nearly impossible, but according to Peter, there are multiple ways metals could work, so I have not achieved the impossible. Myself I know it's not impossible because FStyles has a steel propane tank exactly where his combustion occurs, and many people sell metal rockets with 3+yr warrantees and also, I've done it first hand. It's just HOW you do it that matters.

I suck my stove sucks and that's what haters gonna say, I already know ,
but I'm gonna continue to be warm and happy eating rocket baked apple pies and pizzas with super efficiency, and nobody's opinion will stop my heat or my happiness with or without steel, with or without others opinions, with gleeful joy of personal achievement satisfaction of testing my unit all winter with only success and fun invocation all along the way, so after you keep repeating how metal is doomed, and I acknowledge your opinion, then we can get righ back
On topic:
Anyone else have success using metals?

John I want to first say I love your creativity and things you build.

John you keep repeating error over an over.

you have also been repeating many times that i have a metal feed magazine and thats all it is a feed magazine not a burn magazine. it has a refractory cement base inside where the flames and embers lay and the fire brick butt up against the burn tunnel entrance and there is no metal in the burn tunnel area where the high heat is present. the feed magazine is NOT the burn tunnel. i can tell the the molecular structure of my tank has weakened around the lip of my burn tunnel entrance only a few centimeters but it can not recede or corrode because its not in the burn tunnel where the metal melting high heat is. i measured the temp of my propane tank and it gets about 900+ degrees and not enough to corrode but it will weaken the structure... i could care less about the lip entrance since it only holds the wood and isnt designed to burn it there.

you keep repeating you have done the "impossible" or "succeeded"

1. You have not done anything impossible or broke any laws of physics.
2. keeping your low temp metal at a low enough temp so it doesnt degrade is success in building a very nice wood stove that doesnt corrode and many people have applauded that fact.
3. the concept of a J or L tube wood stove has existed for hundreds of years and has never been called a "Rocket" anything.
4. The Rocket name has meaning here and if it didnt then all these look alike stoves and real rocket stoves would be under the same forum section of "wood stoves" and not rocket stoves.
5. No one here will say you are not warm or have not created a stove that can burn wood with out corroding the metal.
6. the point that is being made is the definition and meaning alone and to stop this watering down of the name and when you dilute the name you dilute how it is built and its permie style environment, coexistent, sustainability, and efficiency performance.
7. I and others have always stated if you insulate anyone's heat riser or your metal burn chamber and heat riser so it can heat up to proper rocket stove temps to burn as close to 100% of the fuel and gasses as possible without allowing unconsumed gasses to pass through you will degrade the molecular structure and weaken any metal wood stove. PERIOD!

The name Rocket of this forum section has meaning here regardless what you want to call and define it.

Rocket Mag evolution timeline: http://www.permies.com/t/52316/rocket-stoves/Rocket-stove-heats-water-pics

Rocket Mag Thread: http://www.permies.com/t/54074/rocket-stoves/Rocket-Mag-heater-Rocket-Mag

F Styles

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my point made.

F Styles wrote:

Satamax Antone wrote:The fumivore, not a rocket!

http://donkey32.proboards.com/post/20514/thread

the L and J wood burning core concept has been around a very long time and was never called a "Rocket" anything.

John says:
I suck my stove sucks and that's what haters gonna say

John thats absolutely false. I love your creativity and you better recognize your capabilities and amazing ingenuity and if you checked out that UL tested wood stove Sky stated he is doing what you already have done without getting advice from him to put a shiny stainless steel insert into your burn tunnel and riser to protect your metal... brilliant idea for a wood stove if i may say so. you have been misunderstanding me. I like your wood stove constructions.

Sky Huddleston wrote:Stainless Steel is not a conventional insulator. But mirror polished SS is a great reflector of heat, it has superb Emissivity properties to reflect almost all the radiant heat back into the combustion zone. Of course radiant heat is only a fraction of the heat that should ideally be insulated. This is why down the raod we are going to use a full length SS liner

Rocket Mag evolution timeline: http://www.permies.com/t/52316/rocket-stoves/Rocket-stove-heats-water-pics

Rocket Mag Thread: http://www.permies.com/t/54074/rocket-stoves/Rocket-Mag-heater-Rocket-Mag

Satamax Antone

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Well, i gonna tone things down guys.

Reflective insulation only work when the material is reflective. Any hint of dust on the surface of the material, let alone ashes or soot, and it's worthless.

That's part why satellites are assembled in white rooms.

https://en.wikipedia.org/wiki/Radiant_barrier#Attic_dust_accumulation

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

F Styles

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Satamax Antone wrote:Well, i gonna tone things down guys.

Reflective insulation only work when the material is reflective. Any hint of dust on the surface of the material, let alone ashes or soot, and it's worthless.

That's part why satellites are assembled in white rooms.

https://en.wikipedia.org/wiki/Radiant_barrier#Attic_dust_accumulation

Its interesting you said that, my mom worked on military contracts building the same kind of stuff and they had to go through vacuum rooms and put on smocks and foot booties before they went in to build these things so they did not bring in dust. even the floors had tiny holes in them constantly sucking and circulating air. it was neat. Thats what you call rocket science. maybe thats where i got my mechanical inclinations?

oh no! Satmax came and through dust on the fire

I was thinking the same thing... one bad fire from a windy day, or some punky wet wood or a bad burn and the mirror is beat and the heat reflection gone until you pull it out and re clean and buff it.

Rocket Mag evolution timeline: http://www.permies.com/t/52316/rocket-stoves/Rocket-stove-heats-water-pics

Rocket Mag Thread: http://www.permies.com/t/54074/rocket-stoves/Rocket-Mag-heater-Rocket-Mag

Tam Deal

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Is it true that a Rocket Stove needs to be hot enough to burn up all the fuel? I get what they are doing when they are, but is that actually what is going on in the majority of the little piles of brick that people are cooking their chow on? The pics I have seen the fire is licking their pots (though the pots are staying pretty clean). Sure a lower temp unit is not going to get anywhere near the heaters that are said to produce 1/10th the pollution at 1/10th the cost, but that is not why people are building rocket stoves that they use much like a BBQ, and I am not really sure what their motivation is, but as long as they are more efficient or usable than a campfire, mission accomplished. Isn't the Kelly Kettle a somewhat rockety appliance, made of metal, that does not operate at 2000F +, and has an avid following.

John McDoodle

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F Styles wrote:my point made.

F Styles wrote:

Satamax Antone wrote:The fumivore!

http://donkey32.proboards.com/post/20514/thread

the L and J wood burning core concept has been around a very long time and was never called a "Rocket" anything.

John says:
I suck my stove sucks and that's what haters gonna say

John thats absolutely false. I love your creativity and you better recognize your capabilities and amazing ingenuity and if you checked out that UL tested wood stove Sky stated he is doing what you already have done without getting advice from him to put a shiny stainless steel insert into your burn tunnel and riser to protect your metal... brilliant idea

i like the name FUMIVOIRE and im willing to call it that. can anyone translate me the french? satamax perhaps?

positively optimistic 🙂 https://www.youtube.com/@613Builds

Glenn Herbert

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A rocket mass heater must be hot enough to burn all the fuel, or else it will generate creosote and deposit it inside the mass flue channels. A rocket stove can get away with less complete combustion because its exhaust is going fairly directly to the atmosphere, and any deposits are likely to be on easily accessible surfaces. The best rocket stoves will be adjusted so the fire gets very hot and the flames just reach the pot, being nearly completely combusted and leaving little soot. 2000F is not essential for a RMH, but the consensus seems to be that about 1500F sustained temperature is the minimum for really good combustion. There are a few compounds that take 1800+F to crack.

F Styles

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I think it generally means "for all to witness no smoke" to "view it without smell or smoke"
please correct me if i am wrong.

Rocket Mag evolution timeline: http://www.permies.com/t/52316/rocket-stoves/Rocket-stove-heats-water-pics

Rocket Mag Thread: http://www.permies.com/t/54074/rocket-stoves/Rocket-Mag-heater-Rocket-Mag

Satamax Antone

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Fumivore is best translated as "smoke eater"

Fumi, as in fumigation, = smoke in latin.

Vore, as in carnivorous, = which eats

It's as simple as that.

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

John McDoodle

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I'm referring to a translation of the long French write up below the fumivore diagram, seems to be descriptive

positively optimistic 🙂 https://www.youtube.com/@613Builds

John McDoodle

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F Styles wrote:my point made.

F Styles wrote:

Satamax Antone wrote:The fumivore, not a rocket!

http://donkey32.proboards.com/post/20514/thread

the L and J wood burning core concept has been around a very long time and was never called a "Rocket" anything.

positively optimistic 🙂 https://www.youtube.com/@613Builds

Glenn Herbert

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I know Max could do this better, but the practice is good for me

It's been a long time since high school.
[Brackets] indicate uncertain or imprecise translations.

Chapter II

Of simple smoke-eating furnaces

Dalesme's smoke-eating [chamber]

For a long time people have searched to establish furnaces or chambers of combustion which would have the property of consuming their own smoke, and of delivering from that inconvenience the neighborhoods of foundries, [?brass casters, or cooking establishments?] and [?usines?].

Dalesme, French mechanic, appears to be the first who had tried to consume the smoke. He exposed his procedure at the Saint-Germain [showroom] in 1685.

His chamber, of reversed flame, was placed at the lowest part of an inverted siphon, of which one of the branches, serving the function of chimney, was longer than the other. Once the interior of this long branch was heated, it established for itself a current formed by the air flowing from the little branch which, [??blowing on??] the flame in the manner of making it pass [under, through] the grille, operated the combustion of the furnace.

Lahire, in 1689, made several experiences on this procedure, of which he presented an exposition which one finds in the Memoirs of the Academy.

John McDoodle

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merçi Glenn

in figure 1 -
... it appears to be burning and heat rises from the feed tube?
if so, maybe mine is a reversed fumivore -

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Glenn Herbert

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I think that was a drawing by an artist who hadn't actually seen one in operation, and couldn't imagine how to show the fire without flames rising from the feed.

John McDoodle

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lol yeah i hope not

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Bruce Woodford

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John McDoodle wrote:I was discussing "using metal in the burn chamber and heat riser" and I was told to start a new thread because I wasn't having failures? I still want to discuss the topic of using metal and I want to know if anyone has any sort of long term success with metal, stainless, or ceramic coated mild steel, like myself...?

Maybe we can discuss our success stories here, or maybe you want to share your findings, or maybe you just enjoy prototyping with outdoor cook stoves.

Personally I have burned my first rocket hybrid experimental stove for over 50 documented test hours of intense burning, and my stove is in great condition thus far, however my internal mass and stainless hi temp duo-therm anti-corrosion liners keep the steel surfaces at a regulated operational temperature.

So what's your metal rocket story? My rocket and tests are documented, and soon i will post photos of my internals to show the condition of the insides of my clean burning rocket hybrid, so keep an eye out for that coming soon also.

Hi John,

Great to meet a fellow Ontarian on this forum! I'm relatively new here and am building a steel RMH and believe that one can work quite well with a noninsulated and air cooled core! Have you seen the thread I started called "Think outside the box re metal RMH cores"?

Seems you're building/using a rocket cook stove and I'm building a mass heater, but the same principles apply. If you can keep your metal from glowing in the dark (about 800F) there should be no heat corrosion. That's the principle on which I'm working but still get temps comparable to traditional insulated refractory cores.

Let me know what you think.

Bruce

John McDoodle

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hi bruce!
i havent been on here since like january lol
i have made a few prototypes for compact rockets WITH internall mass, so mine are mass heaters also. my last couple prototypes are designed to be efficient, small footprint , able to provide heat, cooking surface, oven, and possibly hot water and/or run on pellets. the latest cast core i made has been curing for months and it weighs about a quarter of a metric ton and it has wheels lol. i shoot for high ignition temps of the internal combustion air, but i also try to keep the SURFACES below functional operating temp. you can have over 1000f combustion, with SURFACES below 700. the temp of the surface is always lower than the internal air and fire. the external surfaces might reach only 60% of the internal combustion due to the external surface temp and thermal conductivity.

like i said, i havent been on here in a long time, permies.com that is. ive been focusing on my old summer sports car and my youtube channel, but winter is coming and i will be working on my rockets more in the near future! perhas i will find your "outsude the box" post when i have time.

thanks

positively optimistic 🙂 https://www.youtube.com/@613Builds

Bruce Woodford

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John McDoodle wrote:hi bruce!
i shoot for high ignition temps of the internal combustion air, but i also try to keep the SURFACES below functional operating temp. you can have over 1000f combustion, with SURFACES below 700. the temp of the surface is always lower than the internal air and fire. the external surfaces might reach only 60% of the internal combustion due to the external surface temp and thermal conductivity.

Thanks John,
Yes, I have leaned the same thing.... I have combustion temps over 1220 F but the vats majority of the surface of my combustion chamber is under 700F. Adding cooling fins to lower the temps of the hot spots!

Keep in touch as you get back top work on your rockets!

John McDoodle

Posts: 617

Location: ontario, canada

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posted 8 years ago

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i will, but i should warn that my latest cast core that has been curing since spring uses zero metals in the flame path. i do have a functional compact vertical RMH, which is made from steel AND has a casting internally also but im no rocket scientist

ive just been experimenting with the rocket design hands on, only for a year or two. im just learning myself and trying to avoid my reliance on propane a bit

positively optimistic 🙂 https://www.youtube.com/@613Builds

Peter Chauffeur

Posts: 57

posted 5 years ago

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Hi John.

I recently posted my prototype Rocket Stove / Mini Thermal Mass Heater on this site. I ran it for 3 Years from fall to spring each year and posted a thread on its autopsy. I used standard thick walled square tube for the burner and 3 inch diameter muffler tube for the riser. Now 3 years of start and stops every day ( as I shut the pellet stove down each night} is a lot of cycles and the riser did manage to suffer fatigue and I think it was due to bell housing not being able to dissipate the heat quickly enough. I am currently building a Mark 2 version and I am recycling the burner assembly for two reasons: 1} The burner assembly works very well and 2} it will be a benchmark for when I actually have a little more time to make a second burn tube with a larger hopper and continue my experimentation with steam injection in the secondary air inlet. Check out my design, perhaps we can exchange ideas.

Peace Health Happiness
Peter Chauffeur

Self-Proclaimed Renaissance Man and Gizmologist.

Satamax Antone

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Location: Southern alps, on the French side of the french /italian border 5000ft elevation

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posted 5 years ago

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Hi Peter.

Well, a word of warning.

If your metal hasn't destroyed, you're not burning well. I strongly recommend using firebricks, superwool and the likes. Cob too. Fireclay. fire cement etc. I don'k know how many rockets you have built, but i'm sure that if the metal hasnt spalled, you're not reaching rocket temperatures. So, this also means your flue should be checked for creosote etc.

Hth.

Max.

God of procrastination https://www.youtube.com/watch?v=q1EoT9sedqY

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