I've been looking at every conceivable rocket stove design for a couple weeks now. Looking at the RMH designs of every sort.

As well, been going back in history and taking a look at what was compared to what is today and all this claimed "new technology" surrounding rocket stoves and rmh design with even bigger claims of how efficient rocket stoves are etc etc.

At first, I was real excited about the "new tech" RMH and rocket stoves, but, I've got to be honest, I'm not seeing it any more.

Thermal mass storage using fire as a heat source had been around for a very long time, beyond Roman times. Burning wood efficiently as well.

Looking at Rocket stoves and the RHM designs "of today", I see using them, I see a constant inherit problems from every single one built.

Yes rocket stoves burn hotter. Too hot from what I see. With a constant problem resulting at the blast area and exhaust tube. So does that make them more efficient or less? In my humble opinion, les efficient. Much less.

Claims of how it burns all particles of wood while at the same time burning the steel, stainless, fire brick and just about anything else in the blast area it's not a sign of efficiency. Wood is much softer and has a much lower burn temp than steel. So you might be burning all thew gases and soot released by burning wood but your also burning and releasing particles of steel and the like. So I don't see the benefit.

That coupled by constant replacement of burn tunnels, risers, containment tanks that are degrading due to the high temps makes then less efficient and more detrimental to the environment than a stove that burns at the correct temperature to burn the wood and soot with minimal by product/pollution.

I'm seeing the "smokeless" stove designs, which include the TLUD etc etc. Now we go from a burn tunnel that sucks air from the inlet of the "J" tube, to sucking air in from the front as in a batch load, to sucking air in from underneath the fire. A Dakota fire pit does that.

So the only added plus is a containment area at the top to hold the soot and add air for a longer burn time. But the TLUD is a horrible design for cooking let alone heating.

Case in point are several smokeless designs,

such as this one from MIT,


Or the supposed "Smokeless" Chulha (which I've read is actually "les smoke not smokeless"


Too many smokeless designs to post all here. But the fact remains all claim to be super efficient, clean burning (like the TLUD claimed, only less not stating it's that clean of an output) And with out the super high temps of a rocket stove or rmh drum design.

As for thermal mass storage and heating seriously folks, it's been around and used very successfully on much grander scales than heating a 1000 square foot room. Heck the Romans heated their public baths that way.

My point being, this is not new technology. And though I was real excited and telling everyone about these great RMH's I was reading about with 55 gal drums. I'm now seeing them as being more harmful than good.

And to top it off, there are back draft issues...?

I'm not trying to smelt steel, just cook and heat a very small area by comparison to a Roman public bath or Medieval Castle. Can you imaginings facing the King or Roman Emperor telling them you have to tear down the fire pit each season? Hate to think of the retribution upon that conversation.

I'm thinking now that some of the old, really old technology that actually worked and was used that is being revisited with claims or giving the perception that this is "new technology" be relooked at with perhaps a simpler approach to the solution.

What's wrong with ash as an insulator? Or clay as the container? Air being brought in from the underside of a fire creates a better burn, I learned the first time I built a standard camp fire as a kid.

Here's a example of simplistic design using simplistic materials such as ash and clay.



Is it a rocket stove? Has similarities you can't deny. Not smokeless I'm sure, but not smoking like an open pit fire either.
Not burning away any steel or tin or fire brick either.
Is it as efficient art burning wood or wood gas. I don't know.
But I'm not seeing the inherent problems associated with all these new fangled rocket stove designs popping up everywhere with claims of grander at how great they are and are going to save the planet while they don't cause pollution.

No suspect meant to those that design and build rocket stoves or RMH's but, as stated, I'm just not seeing it any more. I'm going back to simpler designs that do the same with out the issues.

Maybe I'll have to build a Roman bath in a Medieval style Castle if that's what it takes to get something that truly works and is green efficient. I don't know, but at this point, I'm disappointed with my findings.

- chase -

"I'm going back to simpler designs that do the same with out the issues.". Can you please elaborate and show us your specific build/design?

Correction, I meant to type,

"Is it as efficient at burning wood or wood gas. I don't know.
But I'm seeing the inherent problems associated with all these new fangled rocket stove designs popping up everywhere with claims of grander at how great they are and are going to save the planet while they don't cause pollution."

Sorry about the type-o's and Swype errors in my first post. Hope you can understand it without to much problem.

@ Aaron Festo, not seeing were I stated that. Will look again...

The designs I see presented here either don't need anything more than cob or they last indefinitely without repair. Metal rockets do tend to last only a single season,and this is always pointed out when they are discussed here.
A brick bell can take the place of the barrel, which itself lasts quite a while.
Making barrels just for stoves is perhaps a poor use of resources, but ignoring a positive way to use an existing waste stream is certainly not more sustainable.

I would like to see evidence that stoves burning at lower temperatures are as non-polluting as the rocket stoves.
I am not aware of anyone advocating the use of tluds for cooking. There are many charcoal producing stoves intended for cooking on. They are demonstorably more efficient.
In places where fuel must be paid for by coin, or blood, that really matters.
The Roman Empire is not what I think of when I think sustainable,built on ever expanding circles of conquest as it was.
The systems you described, were they in most dwellings?
A decent rocket stove can be built from scrounging materials.
This is not as true for many other designs,ancient and modern, nor are most designs as clean burning.

In regards to the TLUD. Shown below for... cooking.



Worst design ever, extremely unstable. Too easy to knock over. As many rockets are when designed this way.

As for the Roman empire, I'm referring to their thermal mass heating. Not the empire itself. We can save that for another thread.

As for the RMH and the use of metal in the riser etc. Yes it's being brought up. And speaking of things going up is the list of materials not suitable, that break down. I've seen tin, steel, stainless steel, cement, fireplace motar, fire brick and so on make the list of unsuitable materials. Your left with, ceramics... And what else.. There was another. Anyway, you get the drift.

As for a lower temp stove than the high temp rocket stove or RMH burning cleanly. I refer you the TLUD video above again. He states how clean it burns.

And for further review, I'll submit MIT's data sheet on their stove, which is really just a modded Sibley stove (civil war era) I think that's the name of it. Rather than a straight up exhaust, they lowered it to the side.

CO2 emissions over time.


O2 concentrations


Temperature over time


And that's just one design. There are many other basic designs. And many, many from times of the past, that are smoke free, efficient, etc.

Not everything of old and perhaps forgotten engineering has made it to the net yet, which is something to consider as well.

- chase -

The three-stone fire has been used forever, so longevity is not necessarily an indicator of efficiency. It is an indicator of effectiveness, sometimes in spite of drawbacks like pollution.

I don't see what relevance the comparative O2 and temperature graphs have in the MIT case... more info is needed to tell that. The CO2 concentration is nowhere near as low as the batch boxes that have been tested recently, which is an indicator of less than complete combustion. No visible smoke does not mean no smoke.

I was asked by someone if I thought rocket mass heaters were sustainable. I answered, no, they are a transition strategy. They are a way to help us get from completely unsustainable way of life to solutions that might be more sustainable. Are they the perfect solution? No. Can they be improved? Yes. Do RMHs help us think about how we interact with our environment? Yes.


Masonry heaters have been around for a long time. What is appealing about RMH, in my opinion, is that they can be made from waste materials, inexpensive parts, and local sourced materials. I like to think of RMHs as a symbol of transition thinking. "Hey, these waste materials and locally sourced mud is keeping me warm."

Glenn Herbert wrote:The three-stone fire has been used forever, so longevity is not necessarily an indicator of efficiency. It is an indicator of effectiveness, sometimes in spite of drawbacks like pollution.

I don't see what relevance the comparative O2 and temperature graphs have in the MIT case... more info is needed to tell that. The CO2 concentration is nowhere near as low as the batch boxes that have been tested recently, which is an indicator of less than complete combustion. No visible smoke does not mean no smoke.

Why bring up three stone fire management. Obviously countries that use this type fire management didn't progress past it. That's not a viable fall back, nor does it discredit other societies that progress way beyond that as far as longevity is concerned.

Using fire, in itself, is primitive. It's use for heating, cooking, manufacturing etc is in itself an indicator of it's efficiency and obvious longevity over time.

Societies fall, and with them, knowledge lost or forgotten or no longer needed as a new widely excepted means takes hold that does the same thing. I'll agree to that much, but it doesn't necessarily discredit the old tech. Nor does it make the old tech less efficient or viable a solution. And most all fire burning tech is in realty simply a revisit to past engineering and solutions that are no longer in use or rather common place today by most modern societies, if you want to call them modern that is.

I don't know why people bring up the three stone fire management all the time when discussing fire boxes. The three stoves is just a means to hold a pot or container above a fire. That's not a fire box design rather a lack of one.

Since the areas that use a three stone fire primarily for cooking, where the MIT smokeless (and other designs) are likely to be used, hence it's their comparison. Not mine.

I'm not disappointed with the three stone fire management system. I'm disappointed with what I'm finding with Rocket stoves and RMH designs. And people acting and portraying this as if it's new technology. The use of a 55 gallon drum might be new, but burning wood cleanly, efficiently and heating a thermal mass to heat something else such as a living space or water supply is certainly not new.

It makes not only ecological sense but economic sense that before free Romans built a heated public bath house they set about finding solutions for given problems. Efficiency being one of them. Materials to be used in building them another. As well as other factors involved. And I'm just using that as one example. Heck the Roman empire lasted over a thousand years (eastern) so I'd say there's some longevity there.

But there were a lot of very small societies with brilliant engineers that came up with viable solutions and engineering. Most are familiar with the Roman public baths, while Greek, Iranian, Japanese engineering is not as familiar to most, at least here state side.

Almost 5/600 years ago the L flue was development as a mod to the Franklin stove. (Rittenhouse) which Franklin's stove used an inverted siphon, which even then wasn't new technology.

Funny, they had a publication called "The Art of Saving Wood" in 1618 which new efficient stove ideas were published. And that's just from the European sect. There not the only ones that burned wood. But even then, they were looking at efficiency.
It's just reinventing the wheel in my opinion. Though fire containment was now in steel fireplaces.

Rocket stoves RMH's reach temperatures in excess of 3000°. Is that truly necessary? Or is it like using a sledge hammer to drive a tack to hang a small picture on the wall...?

If you'd like to read the full article and specs on the MIT smokeless stove the link is HERE.

I still stand disappointed in my findings with stoves and barrel RMH's at this point. If I wanted to start a steel refinery or a blacksmith shop, I bet they would be great... I don't know. Just seems like overkill at this point.

Unless your burning Ebony or some other super dense wood.

Just my 2 cents.

- chase -

Edit. And yes Glen, I agree 100% with your statement that just because is not visible doesn't mean there's no smoke. I'd love to see a requirement made of those making claims that an emissions test be done at the end of the exhaust pipe to see what is really being emitted into the air. As well as some other tests of the internal works if applicable. Efficiency percentages at the 100% mark I haven't seen yet from anyone's design. New or old.

As a matter of fact I think there was an article that is calling for such tests in light of so many trying to cash in on stove designs for undeveloped countries that use wood as a primary fuel source with claims of these stoves being smokeless, being high efficiency, etc.
I guess greed has no boundaries. That [greed] sadly enough, has most certainly proven a longevity that constantly needs to be put in check.

I'm not sure who said firebricks are unsuitable. Some are better than others but even the most basic bricks can be used.
Let me address the idea that rocket stoves are reliant on high energy technology:

Flip and John Andersons Rocket Kiln

Cob and sawdust make a rocket kiln that fires other rockets. Too high tech, or hard to do?

The TLUd you show there is not well designed for cooking. Turns out there might be some good tlud designs for cooking, but that ain't it.
TLUDS burn some of their fuel as gas, leaving the carbon. Rockets take it all. Both are evidently clean. But are you dissing the TLUD for being a poor source of heat for comfort and cooking, or are you lauding for lower temperatures? I am not actually sure about their temperatures, but since they leave behind charcoal and charcoal is noted for burning hotter than wood, I suppose they just might burn at a lower temp.
The MIT stove might be great, but is it cheaper than cob ? is it cleaner than a rocket?Than a batch box? than a MUD batch box(yes, they exist)?
It uses sheet steel, so no more sustainable than a 55 gallon drum. It's designed to burn PLASTIC, and it describes how the smoke is carried out of the house.
It is compared to a 3 stone stove, right there in the link, which is why that comparison was brought up here.

Misinformation is all too common when it comes to rocket stoves. The highest temperature I've seen reported was 1900F at the center of the flame inside the heat riser. If someone has a link to higher test results I'd like to see it.

I'm one of the biggest sceptics of the claims made despite not voicing my opinions here. But some of the things claimed just make me shake my head in disbelief. I have better things to do with my time that to take issue with all of them, but incorrect informaton about things as simple as the melting temperature of metals should at least be accurate. But no. I keep seeing numbers that are simply wrong.

All those YouTube videos with stoves made from steel pipe and boxed steel could have been made from wrought iron and been just as usable and just as resistant to meltdown, (although 446 stainless would be nice). Check out metal melting temperatures here:

http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html

I personally think these stoves when used as stoves are a poor to fair design that could be improved, but as heaters, they're ok stoves for use outdoors.

Since they can't be independently tested using epa testing, there's no way to know how they compare with two stage combustion stoves like the Lopi Endeavor rated at 82% efficiently. And given the choice, I'd rather build my own stove or modify an old one that's stood the test of time.

Now if only spring would come early.

Keith.

@ William,
The claims of high tech are not mine. Nor the builds over my head or something I find complicated.

The three stone fire pit has been brought up too many times when discussing rocket stoves or RMH's which use rocket stove design for the fire box. One might as well say open fire pit as three stone fire... pit.

I could sit here and show video after video after video of either rocket stoves or RMH's or derivatives thereof that show major degradation of the interior.

I can show one built in a aquaculture greenhouse that the following materials used failed miserably. Stove pipe riser. rock wool, fireplace masonary cement and I believe fire brick was the last when doing the temp repair. Not positive on the last one so don't hold mange to it.Others have shown fire brick to fail. Unless it was a special type of fire brick. Which lasted longer..

The MIT Smokeless was not designed to burn plastic, but yes that is one of the fuels they apparently do burn in these countries. Why, I'd like to know, or do I? That's just stupid, burning plastic that is.

The sustainability of the sheet metal it's made from is not at question here. Not for myself anyway. But... in the MIT design, it's not failing as miserably as it is when used in the rocket stove or especially, the RMH. And as stated, that is just one, singular, smokeless design.

All claim high efficiency, and to be smokeless.

@ Keith,

Who holds the RMH workshop..? Wein something or other. Not sure of the name. Their video states that they are reaching temperatures exceeding 3000°F and did not recommend stove pipe or stainless steel for the riser in the RMH. The one most here are familiar with, with the J tube or batch feed with the drum over it.
They're suppose to be the experts...Not me.

Again, I can show video after video where the RMH fire box fails.

And yes, mostly found on YouTube, where most people post their vids. Including those that seem to have success like these people that have the workshop on RMH's. Or those that sell the DVDs.

And let me state, the thermal mass storage/release of the heat is great. It's a time proven working and effective solution. I have no issue with that part of any design. Some designs may be better than others, more efficient than others but the principle works. Both in theory and in practice.

No one talks about the back draft issue related to rocket stoves and RMH's. RMH's are plagued with issues. Mostly due to the fire box from what I'm seeing. I'm over simplifying it but there in lies a major portion of the problem it seems.

If one can take a much simpler design, built from clay, stone, ash, sheet metal or other wise. That's not plagued with the issues that accomplishes similar results or close to results. Why go with something proven to fail from so many directions?

And I don't have to "claim" is the new high tech green way. As many are.

I could make the MIT smokeless out of a upside down flower pot with a hole cut in the side. Make the sides 4"thick and I have a thermal mass. Not a huge one, but a thermal mass just the same.

I may try that chime to think of it. Hmmm...

I'll reiterate, I was so excited when I first read about the RMH. Couldn't stop talking about it for days.

But now, not so. Not after seeing all these other designs. All of which, including the RMH are based on old, really old designs. Whether they work or not.

The Franklin stove/fireplace failed. Why?
Due to problems with its reversed/inverted flue.
Similar problems are being reported by those building the RMH.
Special care has to be taken to "tune" it.
A 4"inch pipe design is considered advanced, etc etc.

And don't get me wrong, some do work. There's some great looking stoves based on this design.

Do I really need over a thousand degree temps to cook with? Heat a small area with? Heat water with? Heat a thermal mass effectively and efficiently. the answer is no.

Can a reburn chamber be built for unburned fuel source? Highly likely. What that temp needs to be at, I don't know.

Are there byproducts being released when metal reaches its threshold temp? Or exceeds it and starts breaking down? I suspect so. How is that green? Efficient? Environmentally friendly? I again suspect not.

I don't have all the answers, but there is thousands of years of knowledge out there from every country that covers burning wood more efficiently and cleanly, as well as thermal mass storage of the heat produced.

Tapping into the ones that are and have proven to work with all the benefits one is looking for is all that needs be done.

- chase -

Well, I'd rather not respond to a bunch of generalities. If this thread were to continue, I'd want to address two points:

Specific builds you find lacking, and where/why.

Specific alternate plans you feel to be an improvement.

Speaking very broadly, I really don't see the objection you are making presents a strong case. Unless you are just tired of hearing claims of fire burning techniques being new. Man has been using fire for tens of thousands of years. I suspect little is truly new. But that's not really the point. The RMH is a refinement of a variety of fire burning techniques.

I think most of your points would be addressed by watching the Woodburning Stoves 2.0 DVD series. I think you can rent it on this site somewhere.

The basics of masonry heaters is quite simple: (1) a lot of thermal mass, (2) a rapid, hot burn, (3) retain the heated air in the masonry long enough to capture it's heat, and (4) ensure a good draft. Everything else is either safety or efficiency improvements.

Aaron Festa wrote:"I'm going back to simpler designs that do the same with out the issues.". Can you please elaborate and show us your specific build/design?

2nd to last paragraph-last sentence.

Guys, i think you're overly skeptic, results have been published.

My only caution is about smaller rockets for heating, say less than 6 inch.

AAbout the results of some research.

http://donkey32.proboards.com/thread/355/small-scale-development

http://donkey32.proboards.com/thread/511/adventures-horizontal-feed

http://heatkit.com/research/2009/lopez-rocket.htm

http://www.mha-net.org/

HTH.

Max.

Metal stove pipe riser?
And it failed. Go figure.
I could post a bunch of videos showing failures of other stoves or long term success in rocket builds but I don't think that doing so will serve any useful purpose.

I look forward to seeing your MIT flower pot stove with reburn chamber.
Perhaps you could bring it to an innovators gathering so the emissions could be tested.

William,


Metal is doomed!

At least for the core, heat riser, feed tube and burn tunnel.

You are also looking at the prototype and development phase of a product, there will be lots of bad ideas floating around until they get sorted out. Like cars in 1902.

William Bronson wrote: Metal stove pipe riser?
And it failed. Go figure.
I could post a bunch of videos showing failures of other stoves or long term success in rocket builds but I don't think that doing so will serve any useful purpose.

And stainless steel and so on and so on... fail
Exactly.

A MIT smokeless out of a flower pot with a reburn chamber, there's a thought. But as I stated, there's thousands of years of engineering, much forgotten. Some lost. But many work, that may bee even better.

A month of burning with consistent falls and issues does not make for success for the masses. Or even a small village in my opinion.

They finally regulated outputs from smelting plants for a reason. And coal burning etc etc. Fears of the plant outputs in China while they go through their industrial age are backed up by learned lessons.Mistakes made that were ignored for too long.

And I'm not saying other systems don't fail.
Failure doesn't have to be a bad thing, unless you don't learn from it.

But then I'm not trying to use a passive blast furnace to toast a marshmallow.

The fact that inflated or uneducated or unsupported claims have been made for RMHs does not invalidate the sober research and development that has been done on them, nor do the misled experiments posted on youtube.

Someone may actually have measured 3000 degrees inside a RMH, I don't know for sure, but that is not likely to be achieved in most good builds. 2000 is possible, and 1500 or more is likely in any good RMH. Yes, these will destroy metal, which is why metal is not used in durable builds by people who know what they are doing, but firebrick is very durable, and with matured practices the typical RMH might come to be designed like some masonry heaters, with a lining of firebrick at the highest-wear areas that is intended to be replaceable without tearing apart the whole core. Castable refractory (especially insulated) is less durable but apparently more efficient, and may or may not come to be the preferred method, perhaps with harder liners in wear areas. There is still research to be done.

Mistaken claims of metal "melting" temperatures aside, metal does distort and/or degrade at the reported temperatures in the presence of oxygen or combustibles. So nobody who knows what they are doing uses it in these areas. The reason there are so many failures is that this is a relatively new (to us, anyway) area with a lot of non-professionals experimenting. Some of them may hit on real improvements. Some already have. There are many, not just some, RMHs that work very well, and deliver heat with radically less wood than established technologies. That is a real-world measure of efficiency.

Basically, if you build it wrong, using techniques known to fail, don't cry about the poor performance or the lack of sustainability. YouTube is known to be rife with poor designs, and making builds that others have already demonstrated to be inferior. So citing improper builds cannot speak against proper building techniques; only against improper building techniques (and is valuable in that sense).

I suggest researching the temperatures at which wood, and volatile gases from wood, burn. These are the temperatures a clean burn needs to sustain. I've looked around too. Just going by memory and not taking the time to look up my notes, I'll say that 1400 F is often cited as a critical temperature to remain above. Are there trace gases that burn at 1600 or 1800 F ?? Honestly, I don't remember with certainty (I'm thinking, yes). I do know I want my burn to stay above 1400 F as long as possible; and I'd be very happy with 1700-2000 F sustained temperatures.

Speaking to the claimed 3000 F peak temperature, I've not seen that documented. Maybe it is true. But I suspect it is peak (or a really big system size), and not typical. Just consider that a great many fire boxes have been built from 2200 F rated fire brick, and they appear to be holding up quite well. That would not be true if internal temperatures were typically in the 3000 F range. Were that the case, it would be a common recommendation to seek out the higher rated fire brick (it is available in the 3400-3500 F range).

I have some operational grievances with the J-style rocket mass heater. But that is not a build deficiency, it is knowing my own behaviour and psychology well enough to know that I will personally prefer the batch box style.

But whatever system you use, you have to get up to at least 1400 F and sustain it to burn the smoke and gases. And I have a nagging memory there are some of the gases that do burn higher, I just don't recall off the top of my head. And that's why I *think* aiming for a sustained burn closer to 1800-2000 F is a better plan. I haven't yet made a build where I built-in thermocouples to measure various test points inside the fire box, so to date I am limited to what I can reach, and that's just a short distance inside the throat of the burn chamber. Or outside the rocket stove.

I remain of the opinion that more than two weeks of research is required to sort this kind of study (I'm several month into this process, so no expect, just another hacker). I commend you for undertaking the research process, but I suspect your conclusions to be premature. Keep digging! And build a beast or three outside and once you get a really good rocket stove design, start trying the other builds you wish to compare to it. Unless you have thousands of dollars for a Testo or similar gas analyser, there's only so much you will be able to measure. I do not know of a cheap and effective gas analyser, although that would be great!

And without a gas analyser, subtle design changes cannot be measured. If you can only measure temperature, you have to use past studies that offer temperature ranges for clean burns, and determine if you can achieve and then sustain those temperatures in the critical areas.

But the logic of masonry heaters seems infallible to me. Burn hot enough to burn the smoke and gases, and there is no creosote to build up inside the heater, and there will be maximum heat available for recovery. So burn hot and fast, trap that heat, and ensure a good draft, and make sure toxic fumes will escape to the outdoors, not indoors.

Glenn Herbert,

The fact that inflated or uneducated or unsupported claims have been made for RMHs does not invalidate the sober research and development that has been done on them, nor do the misled experiments posted on youtube.
~~~~~~~ snip ~~~~~~~

Yes, these will destroy metal, which is why metal is not used in durable builds by people who know what they are doing, but firebrick is very durable, and with matured practices the typical RMH might come to be designed like some masonry heaters, with a lining of firebrick at the highest-wear areas that is There is still research to be done.

Mistaken claims of metal "melting" temperatures aside, metal does distort and/or degrade at the reported temperatures in the presence of oxygen or combustibles. So nobody who knows what they are doing uses it in these areas. The reason there are so many failures is that this is a relatively new (to us, anyway) area with a lot of non-professionals experimenting. Some of them may hit on real improvements. Some already have. There are many, not just some, RMHs that work very well, and deliver heat with radically less wood than established technologies. That is a real-world measure of efficiency.

Research and experimentation are good, but it would help if there had been somewhere like a forum where peoples work was coordinated to record failure and success. And hopefully reduce the former.

Having a place that listed effective and recommended building materials, along with alternate optional products, (like premade cores, or ceramic fiber instead of ceramic lining, etc), would be nice. Similarly for things like heat exchangers for those that find "mass" impractical. I spent weeks hunting up and stumbling onto information. For instance, I thought a stainless steel heat exchanger would be hard to construct because one would normally need a plasma cutter, a tig welder and cnc machine to work with it. But then I found flux cored ss mig wire, masonry abrasive cutting disks and masonry (tungsten carbide) drill bits, could do the same job.

People shouldn't have to hunt for that information for that long a period. A forum should have a library of collectively gathered information relating to its purpose.

I didn't come here to be critical of constructive well intentioned efforts, I came to try and make sense of some radical claims and get the straight scoop on rocket stoves and heaters, but the information I've seen here goes from one extreme to the other.

And before anyone comments about a stainless H.E. doing a meltdown, they should know that when a column of hot flue gases enters a larger and cooler area, its going to cool down partly because its supposed to transfer heat to the metal and partly because the hot core mixes with the cooler surrounding gases.

Regarding the distortion of metal you mentioned, to thin a metal, or the use of common steel, instead of mild steel, would be my guess. Wood stoves/heaters have been around long enough that one would think most people knew they used thick metal. I don't know what they use on "Air Tight" stoves, but I've seen them buckle and bloat, (and rust out).

Looks like the weather is going to take a turn towards warmer here over the next few days so I may be able to squeeze in some experimentation of my own.

Good luck!

Keith.

Thanks Erik and Keith for chiming in with some really useful insight and info.

I was about to look up the burn temps of various woods as that, the type of material, is key as well in determining needed burn temps with any stove.

And I do like many of the Masonry (sp?) Heaters. I was just looking at some. Very nice design work. Which I will state an off but valid point, the 55 gallon drum just plain sucks aesthetically. I'm sorry, I'm just not into whatever interior design look that falls into. lol. The bench looks cool...

Okay, you made me go find the reference to 3000 degree temps.
And it is stated by none other than ernie and erica Winser in their classroom on RMH's.

Heeres the video... (go to about the 20 minute mark, and it's mentioned at 23:45 I think... But watch from 20:00. Their discussing the riser)


They mention having melting of SS which occurres at about 2,900°F.
And degradation of stove pipe, etc, etc.

Something else I wanted to mention.... oh yeah.

Just for the fyi, in 1618 before Franklin a publication came out by Kessler I think his name was. Anyway, he is touted with being the first to publicize his fireplace that used a inverted exhaust. Curious enough, once translated, it uses similar principles as the RMH fire chamber, down or inverted draft, etc. And he stated, "due to the increase in draft and occurring high temps he used ceramic in the fire burn chamber..."

That's almost 400 years ago.. instructions in German, so I can understand how some missed it. But not others... I found it in less than 24hrs once looking at inverted flue designs of the past. I knew all this was old, had been done before and someone might have left or wrote an Instructable. All, is not on the net, but some of it is... you just have to look for it.

When all else fails, read the instructions as they say.
So there is the answer, solution if you will for the riser/burn box area.

And they have high temp ceramics that can handle temps beyond 2,000°C / 3632°F... next problem...?

I'm going to jump back to the Masonry heaters for a moment, just because I need a break from this topic.

I liked the Kachlofen design, or found it interesting at the least.
Here's a cut away diagram that intrigued me.



And more images of Masonry Heaters are over at InspirationGreen.com, if interested in looking at them. Some really nice work.

Which brings me back to the RMH...And that ugly ass 55 gallon drum. It's just got to go. Someone has to come up with something that looks like it belongs in the living room and not in a gas station work bay. A decorative box around it, something. Anything.

Just because is made out of recycled or waste materials, doesn't mean it has to look like it is.

Okay, I'm tired... Swyped enough, researched enough for today. You guys do some research and post something I haven't already read about.


- chase -

chase canadé wrote:
Which brings me back to the RMH...And that ugly ass 55 gallon drum. It's just got to go. Someone has to come up with something that looks like it belongs in the living room and not in a gas station work bay. A decorative box around it, something. Anything.

Just because is made out of recycled or waste materials, doesn't mean it has to look like it is.

http://batchrocket.hostoi.com/html/foto.html

http://technologieforum.forumatic.co....php?f=19&t=27

http://s101.photobucket.com/user/sna...60897695502335

http://donkey32.proboards.com/post/12755/thread

https://www.youtube.com/watch?v=VmuBQ08anCs

https://www.youtube.com/watch?v=HE_QRaXD088



And temperature wise, theoretical reachable temp for an adibatic flame burning wood is 1980C° 3596F° impossible to reach without a fan in the actual state of research.

1200C° is atainable in a rocket. I have "melted" a gas bottle in my first rocket core. Well, it sagged under its own weight. It didn't go liquid.

That idea of metals having to reach their melting point to soften and distort or collapse has haunted many discussions... Blacksmiths heat iron to 1000-1500 F more or less to make it soft enough to shape. Copper could easily be actually melted in the right spot in a RMH, steel/iron of whatever grade would be much more difficult to melt but between heat and corrosive/reactive effects it can be destroyed. Some of the published failures have been of structural steel, 1/4" thick or more.

"Research and experimentation are good, but it would help if there had been somewhere like a forum where peoples work was coordinated to record failure and success."

You mean like the forum at donkey32.proboards.com? Just look in the Reference Library section and elsewhere. It doesn't have all the info you mention, but it has a lot of good stuff.

If using materials produced with modern technology is not attractive to you, you can build a RMH entirely out of cob/clay if you can find it with the right characteristics. Many people don't have access to good enough raw materials locally, or want more precise results. 100% purity in all areas is not possible in real life, and it is your call how much compromise you will accept for yourself.

@CC: "You guys do some research and post something I haven't already read about."

Have you read Paul Shepard's "Nature and Madness"?......

If the wiki entry is considered valid, then: "The word permaculture originally referred to "permanent agriculture" but was expanded to stand also for "permanent culture," as it was seen that social aspects were integral to a truly sustainable system as inspired by Masanobu Fukuoka's natural farming philosophy."

Permanence and sustainability are relative terms and are probably debated elsewhere on the site. With the resources at hand, my shop stove based loosely on the rocket heater design and constructed with non-permanent metal is pretty satisfying (hotter than standards wood stove) and pretty low impact (apparent heat from lower amount of wood)....also both relative terms. If I decided or needed to get more into local raw materials, I might consider clay used by the natives of the area for pots and vary the design accordingly. If I got desperate, the Ojibwe and Lakota have lived in this same region of Minnesota for many more centuries than the Euro-immigrants and are another source of information for heating, cooling, feeding, etc.

If you are looking for the ultimate permanence and performance in the unit, build it out of kryptonite, stoke it with di-lithium crystals, and give it the name "Messiah".

John Weiland wrote:If you are looking for the ultimate permanence and performance in the unit, build it out of kryptonite, stoke it with di-lithium crystals, and give it the name "Messiah".

Lol... worth stopping by for.

I was asked to pop in and say something here. Don't have the time to go into too much detail, but I can see a few things that need to be brought up:


72) The most popular form of wood heat is the conventional wood stove. Advocating rocket mass heaters directs people to something that can reduce their wood use by a factor of 5 to 20. Therefore worthwhile. If somebody wishes to advocate something older, I think that would be cool too.

73) The most popular forms of heat are natural gas and electric. I think that the pollution and other problems behind each of those is at least a dozen times greater than RMH. Plus, knowledge of RMH could save people a helluva lot of money. So think it is worthwhile to keep sharing info on RMH and keep improving the designs.

74) I no longer use metal in my wood feed, burn tunnel or riser. And I strongly advise others to not use metal either.

75) Ernie thinks we were going over 3000 degrees with the RMH in the 4-DVD set. Part of what made him think that is that the firebrick on the floor of the wood feed directly under the riser was spalling. If it spalls at 2200 to 2400, and is at a cool edge .... I think suggesting that we were hitting 3100 at the hottest spot is a reasonable assumption. We have since purchased some cones and have done a few tests - but most of the time, the cones sit in their box because we have just been too focused on all of the other experiments. Further, in more recent tests, Ernie suspects that we were seeing temps in the 3500 to 4000 range. This is leading us to a variety of other experiments, including attempting a 4 inch system which would burn much cooler.

76) if we can burn plastics cleanly, then people can heat their homes with garbage.

77) Ernie and Erica will be arriving here in a few hours. I'm hopeful that we will have a shippable core running where the materials cost is below $100 and it might reach temps over 3500.

7 We have a system here where the draw was so freaky strong .... in a modern "ziploc bag" house with the kitchen fan, two bathroom fans and the dryer running at the same time and the RMH roared. I winder if the clothes in the dryer might have been getting frozen from sub-freezing cold air coming in from outside as the dryer was (possibly) forced to have the air run backwards.

To answer the question "Are Rocket Stoves really the answer or adding more to problem?" They are certainly not "the answer" but I think they are "the best solution for home heat at this time for most people in a cold climate." I have high hopes for our wofati projects that will make rocket mass heaters look like a waste of time. But that is still going to require years of R&D.

Overall, the rocket mass heater is a major slam dunk when compared to heating with natural gas, electric or conventional wood stoves. And the best part is: we are just getting started with this. There is heaps of room for optimization.

Finally, as always, if anybody is disappointed with the direction of RMH stuff, then nobody is stopping them from doing the work for what they think is awesome.

@ Paul,

I'm going to have to respectful disagree with you on a couple points concerning the RMH and it's "benefits".

I received a couple emails, (pm's if you will) that gave me some further insight. Showed working models of the RMH, some history (which I loved) and a common ground to question and continue questioning... everything.

And someone stated, "this is not permiculture" and... their right.

I look at the videos of working RMH's and I see them going to this big pile of firewood.

And I questioned myself, "what if everyone had one of these RMH's of rocket stoves?"

The answer is we'd be in serous trouble all over again. The planet especially.

The problem is more basic. Those burning wood as a primary fuel source need to be shown a new better solution.

CO2 is a major problem. We need all the plant life we can get.

And this is not to say the rocket stove or RMH isn't a valid technology worth noting and has use. But it does, in my conclusion, more harm than good.

There are more passive ways we need to look at for global and certain societies solutions to energy, heating and cooling. Even those wanting off the grid need to question their true direction when it comes to energy solutions.

Thanks guys for those emails btw. I enjoyed the contents.

- chase -

I'm going to have to respectful disagree with you

In your latest statement, it is clear that we do have VERY different positions.

And I questioned myself, "what if everyone had one of these RMH's of rocket stoves?"

The answer is we'd be in serous trouble all over again. The planet especially.

The problem is more basic. Those burning wood as a primary fuel source need to be shown a new better solution.

CO2 is a major problem. We need all the plant life we can get.

This is one of many points where we differ.

I think that if everyone had a RMH then we would be using a renewable resource and putting a tiny fraction of CO2 into the atmosphere.




source

Plus, with burning one tenth the fuel, that would lead to AT LEAST one tenth of the greenhouse gasses.

And this is not to say the rocket stove or RMH isn't a valid technology worth noting and has use. But it does, in my conclusion, more harm than good.

And, in my conclusion, does far more good than harm. Far, far, far, far more good than harm. More good, less harm. Much, much, much more good. Way, way, way less harm. And I can write that in a bigger font too:

MORE GOOD. LESS HARM.


Adding some color:

MORE GOOD. LESS HARM.

There are more passive ways

Yeah. Wofati. I'm working on it:




In the meantime, for a conventional home, NOTHING beats a rocket mass heater for sustainability and what is better for pollution problems. NOTHING. You wanna do passive solar or a wofati, or AGS or PAHS etc. That requires building a whole new house.

I followed along this entire thread and wondered where it might lead...positive path or not so much...

All I can do for Paul's recent posts is give it "thumbs up" since he already-has the infinity symbol under his name for apples and I would use my daily allotment of apples up for no purpose. So consider this 100 thumbs up and 10 apples....

The simple things I see about all this is wood burning has been with humans for millenia...we have done it inefficiently (i.e. camp fires) and we have more than learned to do it really well (i.e. masonry heaters...of which a RMH is but a permutation there of.) The latter...in almost all its forms...is extremely efficient and clean burning. They store heat better than any other device, use wood resources so frugally that 3 acres of wood lot can more than take care of a home (several homes if properly built) and few others out there available come close to this. There isn't a single one (masonry heater that is) as simple to build right than the RMH...IF...just some simple design parameters are followed and folks stop trying to reinvent wheels that others already have...

There really isn't much to them...the work extremely well, are relatively simple to build from natural materials and rest on the shoulders of technologies that cover everything from the Russian Stove to Korean Ondol...

If anyone has actually built one correctly and find flaws with it...o.k. For the rest of us that have built them (and many other types) I see them as a major solution in efficient wood combustion well ahead of all others...

my 2¢

I second Jay C.'s post after reading this whole thread. Thanks Paul for Chiming in. I was hoping that you or Erica might add your imput.

I did want to say something regarding Chase's post, and ask several things about RMH potential as well.

Kudos to Chase for taking on the idea of Questioning something that is being highly touted as a cure all. More of this sort of questioning is definitely in order to provide checks and balances with the possibility that something is a fad, and perhaps not worth pursuing with quite such vigor. I do not believe that that is the case with Rocket Stove Mass Heaters and the potential of such designs as innovations as such continue, but I applaud Chase for making me look twice. I understand what Chase was wondering about where that degraded steel ends up and how toxic is that? Good question!-one I've wondered myself, but not enough to persuade me to deduce that RMH were not potentially worth the claims. It would be nice to figure out what those emissions actually are.

Can someone post a link to a design that uses only cob, or some other locally sourced natural materials. Are there actually cob domes/risers? Are those able to sustain these temperatures for long? How thick do they have to be? What is used for forms or are these igloo'd up with bricks of cob? Most that I've seen are steel barrels over the risers. What other options are there for barrel alternatives?

MY 2cents.

Thanks.

Regarding sources of cob. I don't know. My only knowledge of it is what's left over after I eat the corn.

Should Glenn Herbert read this, congradulations!

About a month ago my curiosity lead me to investigate the materials used for those little backpack rocket stoves and sure enough, they used similar materials as used in blast furnaces. I'd seen mention of one of those materials on the donkey site, (ceramic fiber insulation).

But just a few minutes ago, I did a site search of both forums using Google and surprisingly enough, you were the only person on either site to mention refractory metal. Koodos to you.

Unfortunately that means all this talk about metal component failure has been about as useful as a bag of rocks to someone who's called overboard. Since it appears that those few who used, or may use ceramic fiber, don't or didn't know that refractory metal is used to help it structurally and prevent those nasty fibers from going places they shouldn't. Who knows, someday soon people might discover ceramic coatings also intended to help with the same products.

You would think that after all this time and the expenditure of effort by so many people, that this type of information would be common knowledge in both forums. Maybe now someone will make the effort to do a search for this info. I'm getting tired. Time for a break.

Keith.

chase canadé wrote:@ Paul,



And someone stated, "this is not permiculture" and... their right.



- chase -

Hey chase, That was me who said that and I was being a sarcastic dick. I do that sometimes. It's part of my perfection.

That video link I posted was probably the best walk through for making a core I've seen. It payed attention to all the right details and made it seem very easily doable. He even starts the video by stating "I encourage people to explore more sustainable building materials" but that dude was obviously doing something on contract and maybe even trying to pass code. I think making appropriate use of existing materials is permaculture. I mean, yeah rock wool and perlite takes a bunch of energy to make but using it in a heater core is way better than mixing it in potting soil or rooting clones in it. In my opinion anyway. Hell I bet a couple cases of beer in glass or cans uses a similar amount of energy, but I haven't made those calculations and in truth wouldn't even know where to begin.

I'm sorry but you seem to have misinterpreted me - I don't blame you as tone is nearly impossible to convey via text, but since you did I felt the need to bring it up.

I just long for the good ol days of the USP. I way rather pledge allegiance to Pocahontas every morning than a flag.

I hope no-one took offense.

"refractory metal"

I'm not sure what this refers to, but I have never heard of refractory metal. Ceramics of various types are the only things I know of with those characteristics.
If you were talking about my mention of iron in the Lincoln 8 fireclay, that is an impurity in (usually) microscopic particles, not a material that you could identify as metal.

paul wheaton wrote:
In the meantime, for a conventional home, NOTHING beats a rocket mass heater for sustainability and what is better for pollution problems. NOTHING. You wanna do passive solar or a wofati, or AGS or PAHS etc. That requires building a whole new house.

Paul, we come from different countries.

In France, and most of Europe, houses are not stick built. But brick, stones, concrete blocks or poured concrete. Ok that's not the greenest type of house. But they're there, and last for a loonnnngggggg time! So may be they are greener than thought! If you compare the costs and emissions, to the life expectancy of such a house. But my point is not there.


All of thoses lend themselves realy well to strawbale insulation. Two rows of air entrained concrete blocks on the bottom. They are 36cm wide, so bales sit on thoses nicely. Then pile the bales on edge above, holding theses with long screws and chickenwire. Up to the eave. And render with a nice quicklime finish. Then if the roof is up to the latest regulations, extend it a bit if it doesn't cover the bales. Or redo the roof. Roofing is one of my jobs. I haven't managed to find a way to do a nice strawbale roof. Too heavy imho. And our trusses are way heavier than needed. May be they could cope.

The strawbale on edge thing if up to the latest regulations of RT2012 (calling for R4 euro R23 us); and give a euro R value of R6 (R34 in the us) So they consider it on the verge of what a pasive house needs. Plus there's the original walls and may be an old layer of insulation. And thoses thick walls act as a mass.

http://www.myonlinediary.com/index.php/Insulation/US-EuropeanRValueConvertionTables

I need R8 at this point, for the rooves. I usualy achieve this with 26cm of high end knauf glass wool or 32cm of wood wool.


So, in my opinion, exept where flimsy wood is used, You don't necessarily need to build a new house to save the planet

Antone
But you can have a straw roof ? in French -Chaume or as we say in English Thatched rooves
I agree about new vs old houses . I find here in France the availability of old solid houses built to last as opposed to new timberframed frankly wooden tents that I give 50 years max very interesting .

David

I know your waiting for my response. I'm deciding how I want to go about it. I don't mind being the devils advocate and I do like the pretty graphs and the multi color retort. And have a feeling this is going to be a great conversation. But...
And I'll stop there for a moment.

When someone builds something such as an RMH as obviously you have Paul it tends to come with pride and justifications and... a set of rose colored glasses. And I mean that in a good way. You built it for the right reasons.

I'm standing outside the pride, I haven't justified a build though we might have similar reasons or train of thought to be impact consciouse or eco friendly. And most importantly, I didn't get a set of those cool rose colored glasses, I'm actually on the other side of the glass. Rose or any other color.

I have an open mind to all systems. And did when I saw and started looking into RMH's and rocket stoves.

You've taken, as others have, a step in a positive direction to be more eco friendly. I applaud you for that.

As for the RMH in general, I stand my ground.
It does more harm than good.

Now the question is, can you open your mind free yourself of the justifications, not let your pride of what you built, and believe in system wise, interfere. And can you honestly be able to remove the rose colored glasses that naturally come with building such a system or project?

That's not an easy task. In conversing, you'll naturally use one or all of them in your defense or rebuttals. Same with anyone else that believes whole heartedly in the RMH.

Because if you can't, and as stated, it's not easy to do. My response, no matter what approach I take as devils advocate, or what I say. You won't truly hear it or concede when I'm correct. Making any statement or fact I present, a waste of energy on my part. And any rebuttal futile.

So there in lies my dilemma on how to approach my response.

Should I proceed, or just agree to disagree and let it go at that?

Decisions, decisions...

Btw, nice house...!

- chase -

David Livingston wrote:Antone
But you can have a straw roof ? in French -Chaume or as we say in English Thatched rooves
I agree about new vs old houses . I find here in France the availability of old solid houses built to last as opposed to new timberframed frankly wooden tents that I give 50 years max very interesting .

David

Yep David, thatched rooves are insulating. But with rain, they become less insulative. They are drafty too, iirc. And are traditional in some parts of europe, but not everywhere. And heritage architects are a real pain when it comes to non traditional, not looking like the others stuff!

I could do a R12 with two layers of strawbales, but the lower cost of the insulation itself, is absorbed by the higher cost of the wood framing involved. So, for the moment, to me it's no good!

Bye.

Max.