Support RMH Research and Testing

One of the points of discussion at the November rocket mass heater workshop was how to get RMHs permitted by local government.  RMHs aren't a wood stove, they aren't a masonry stove and unless you're a RMH aficionado, which city and county permitting departments generally aren't, getting a permit to get one built and approved is a fairly steep road.

Ernie Wisner and Erica Ritter have been working toward getting the basic RMH tested and approved.  They were able to get a permit for the RMH installation in the Dana Annex but the county/city hasn't yet signed off on it.

To get the rocket mass heater design approved, emissions need to be certified by an accredited lab.  With the stove technology certified, the permitting process for all of us becomes much easier.  We need to get this technology transitioned from *experimental* to tested, something all of us who want to install a RMH need.

Toward that end, I have seeded a fund for testing and certifying the rocket mass heater but funding the project is something I can't do this alone.  I need your help.  If you are an alternative building person, you understand how important it is to get the technology we advocate recognized and approved.  It's we, the little people, who are going to make this happen.  If you think RMHs are fascinating, contribute and be part of the development of this technology.

If you can squeeze some money out for this project, be assured it will be used wisely.  Donations earmarked for Testing Fees will be used specifically for the costs associated with certification using an EPA-certified lab or university.  Certification gets us a big step toward an accepted permitting process.

Donations specified for use in general research will be used for the purchase of refractory materials, water-heating parts and other materials needed to develop test builds.  This is research from which we will all benefit.

PayPal your donation to eawisner@gmail.com.  When you donate, designate whether you want your funds to be used for RESEARCH or TESTING FEES.  Please help me support this worthy project.

Thanks Nori!

Just FYI folks, we are drafting some building code for the City of Portland that would allow a relatively simple permitting process for rocket mass heaters.  Although they are currently exempt from DEQ and EPA due to weight, there is a revision in the works that would exempt only 'masonry heaters' and require other massive devices to get emissions tested.

RMH's are not currently covered by the masonry heater code: there is no burn door; it's not a batch-burn but a short burn cycle with multiple feedings; we don't use ceramic flue liners; there is no gap between the liner and thermal mass; and earthen masonry is also non-standard in the USA.  So the city figures we need to treat it as a separate thing.

So getting emissions and surface temperatures independently tested would go a long way to documenting these as a safe, acceptable alternative.  We think they produce less emissions per heat produced, and per fuel burned, than anything on the market, but lab testing will prove it.

The normal set of tests for a new, commercial woodstove prototype cost about $5,000.  We will need a custom set of tests, on a custom installation at the lab, so we're not sure about the price.  But when we get a couple grand together, we will approach the local UL lab folks about some serious testing. 

All donations earmarked "Testing Fees" will go to the lab fees themselves - we will donate the time to build the prototype, and probably the materials as well unless other "research" donations cover those costs.

Thanks for your interest and support.

-Erica Wisner
http://www.ErnieAndErica.info

ever considered trying kickstarter for this?  I don't know what their guidelines are, but if it was connected with the next edition of the RMH book, I bet it would fly.

2nd the kickstarter thing.

Greetings,

Some folks surf all of a forum and then go link about from information within threads, others stick with only the portions they have interest in. I am kind of a mix of the two and I have been told that this is the thread for technical discussions.

My interest at first was very low, primarily due to design issues noted in the first one I saw coupled with some of the other claims made pretty much because of a misunderstanding on what the person was even saying by themselves.

That said, old Ned has built up a firestorm of sorts through cantankerous ways and a bit of understanding to go along with it.

I have decided to build one of these units, well that is kind of a lie, I am going to watch my students build one of the things and then pretty much test it and run it through a gauntlet of real world and simulated problems to determine more or less some safety parameters around them. More or less just grasping and opportunity for an old man to play mad scientist again. I enjoy taxing the mind, have the capacity and tools to fool about with this in a lot of ways safely.

For you to understand the mentality I entered into this is is somewhat important you understand how I came into it. I came into it from survival boards. I consider much of the way the last 30 years have gone to be negative to the human element. IMHO a lot of stupid people have made a lot of stupid choices that have impacted us all and dependencies are too high, self reliance may soon become a way of life again.

That said, this product does not play a good role in that situation depending upon perspective. My point is simply that one would be "safer" with a drum sitting on rocks piping the flue gases out. This stems from the very low tech side of get the nasties out of the living space easy and fast. When you and your loved ones are hunkered down in a cabin, getting heat in and pollution out is the priority.

Those of you whom have fooled with these things have likely learned they are a bit more technical than meets the eye. I will assume you have already learned that the "anybody can build" turns into "anyone can build wrong" just about as easy. I suppose that will be some what my goal, to determine how not to build and operate one.

The above said, my original thought was to build one the "best" that can be, refractory tunnel properly masonry joints, cutting fire brick, high tech insulation bla bla bla.

Seems some what against the spirit of the device now.

From that perspective I will be seeking information one things to try and develop good practices from what might be available.  It has been suggested that vermiculite is a good insulator for the high temp concentrator tube, could be, there might be better alternatives, things like this I expect to be questioning and seek feed back on. I can also see simple easy to come by alternatives that might vary by region, I mean like simply filling the double wall with powdered lime.

That said I am seeking a bit more input on some of the more "natural" options since my carrer has been filled with improvements made on "computer modeled" substances which are made in high tech plants to be hard to simulate so as to drive the economic machine, you know, the one that pretty much has fallen on its butt the past few years!

This is a safety venture for me, not a capitol one, information will be shared freely, you share what works and I will seek out the "why" it works and what it takes to make it fail.

Bout that simple,

Ned

Ned, big question: Are you going to buy the book before trying to build one?

Ned, buy the book before attempting to build one.  Otherwise you will build a faulty one that won't work, thus conveniently "proving" everything you're assuming about the things.  And I'd try to find some cobbing experts to guide you through the mixing and application process.  It's not as self explanatory as it appears.  That's all I'm going to say to you on these boards. 

Muzhik wrote:
Ned, big question: Are you going to buy the book before trying to build one?

No, I was not planning on purchasing a book. A person whom stated that they have three in operation offered their design.

The unit will not have cobbing on it, the cob serves little to no function as far as the firing of the unit goes. I will likely encase it in water jackets that I can regulate the flow through to simulate multiple levers of loading on it to find the performance curve.

Unless the book is extremely technical in nature and very accurate it would likely be more distracting than helpful.

I have a few questions I am working through to determine some operational oddities and will post em up after I work through them, the book would not answer them I doubt, just simple stuff that eyes would see and have little meaning to some but would tell me a lot about what is going on.

Ned, you may want to re-think things, esp. if you are (as you stated) planning on having your students do the building, implying that they should consider the build to be educational.  I haven't read the book, but I know from stuff I've been reading here and on other survivalist/permaculture websites that there are a lot of design considerations to consider:  what is the area of your burn chamber?  What is the minimum insulation needed in your column?  What is the size of the bell you will be fitting over your insulated column?  30-gal. drum?  55-gal?  What will be the distance between the top of your column and the bell (the steel drum)?  3 inches?  2 inches?  More importantly, will you know WHY the people who wrote the book give the examples and instructions that they do?  And will you be able to answer your students' questions when they ask why the H*LL you're having them do something in such-and-such a way?

I'm also concerned that you won't be cobbing.  Since part of your concern is that the exhaust gasses aren't able to vent and so will "backflow" into the residence, you need to consider the entire system.  Since the purpose of the cob is to extract and store heat, and the characteristics of how it extracts and stores heat are different than those of water, your results will probably not match those in the "real world", and so your efforts will result in an incomplete and/or improper comparison.  Comparing the device you build with a "field-built" RMH will be like comparing a carp to a lawyer: one is a mud-sucking bottom feeder, and the other is a fish.

Actually, a better example would be bumblebees.  There's a story about a mathematician who, through a very complex set of equations and analysis, determined that bumblebees cannot fly.  Since the "real world" bumblebees appear to be flying, which is incorrect: the bumblebees flying although they obviously are not supposed to be able to; or the model used by the mathematician?

You should get the book and build a RMH complete with cobbing FIRST, making sure it is working properly.  If you are a man of little patience, that may be a non-trivial task, yet essential.  Once you get a properly-working model, THEN you can start building different models, altering parameters until you get one that matches your working model.

Muzhik wrote:
I'm also concerned that you won't be cobbing.  Since part of your concern is that the exhaust gasses aren't able to vent and so will "backflow" into the residence, you need to consider the entire system.  Since the purpose of the cob is to extract and store heat, and the characteristics of how it extracts and stores heat are different than those of water, your results will probably not match those in the "real world", and so your efforts will result in an incomplete and/or improper comparison. 

1. This will be fast as I have only about five minutes to peck it out

2. You have a new car so to speak.

3.your new car has an interesting engine that is assembled in a variety of ways.

4. your new car has a lot of proponents, some of which make some pretty far fetched comments about.

5. Some of the people whom have built the car have had failures with it

6. I have worked on the design of some pretty fancy custom car engines to do some really odd things.

7. I have a lab with a dyno where I can test and stress this new car engine and make it fail in a variety of ways.

8. when I share these failures with you you will know why when certain design changes to the engine of your new car it will fail.

In other words, the cob is a heat sink for the furnace, with a few ounces of cob I can determine the rate it will absorb heat, once I know that I can use water rates to absorb heat at the same rate. I can also them alter that significantly and force the furnace to fail, record the data of the failure so you now know that information.

The other information you mentioned above is most certainly important and it is my intent to fully explore the "why"s behind those dimensions, Which are critical and how much tolerance they have, it is critical as these are custom built units and if the burn chamber is not tolerant of length adjustments it needs to be know why so folks do not vary it. We need to establish flow patterns, turbulent vs laminar or perhaps in the heat concentration chamber it is a vortex etc. If we establish those facts there may be things one can do to improve the design that will give the unit more tolerance of variables etc.

If I put the cob on and run a test, I can not very effectivly put less cob on to retry the test under different circumstances. If I use a water jacket, I can kill the flow to only part of the furnace simulating a void in the cob and see how prone to failure such a void might be etc.

What I build will most certainly fail, and in as many ways as possible. I know of no other way to determine the failure limits other than to push them and then you will have the tolerance information to work with across a host of design changes.

Hope that helps, more later.

The unit will not have cobbing on it, the cob serves little to no function as far as the firing of the unit goes.

This sentence alone demonstrates that you have no understanding of how the stove functions.  The cob not only seals the pipes, provides insulation, and stabilizes EVERYTHING, it provides the reason for lighting the fire to begin with.

I am deeply concerned that you have so much criticism for a system you refuse to learn thoroughly about.  If you want to learn about something, do you not agree that it is best to go to the original source?  The personal connection you have with "three stoves" is merely an interpreter of the information in the book, which is in its fourth printing.  If you want to avoid second hand information I suggest you buy the book. 

I'll say it again:  Beg, borrow, or steal the book.  It's a little more than $20, including shipping. 

Go ahead: break a system in to tiny parts, analyze those parts, and believe that the data about those parts yield more than the whole system.  This, in my opinion, is the fundamental flaw of modern science - the inability and unwillingness to study a system as a whole. 

I ask that you refrain from broadcasting your findings as a study of a rocket mass heater.  You'll be studying a partially built stove vaguely inspired by a rocket mass heater, and to report your findings as the scientific testing of a rocket mass heater would be misinformation vocalized. 

2. You have a new car so to speak.

I believe these stoves have been safely used for about twenty years.  I hope for someone else with more concrete knowledge to back me up.

Sure would be nice if Ianto Evans or Leslie Jackson could join the melee and offer some defense of their design and design process.  I feel like it is them more than anyone else who is "on trial," so to speak. 

NedReck wrote:
5. Some of the people whom have built the car have had failures with it

By "failures" I'm assuming you mean having toxic gasses leak into the residence.  I'm not aware of any such events.  Can you document this claim?

In other words, the cob is a heat sink for the furnace, with a few ounces of cob I can determine the rate it will absorb heat, once I know that I can use water rates to absorb heat at the same rate. I can also them alter that significantly and force the furnace to fail, record the data of the failure so you now know that information.

FWIW, cob has an R value of 1.  That's assuming it's properly made.  Since the composition varies slightly based on the locally available materials, you'll need to either become expert in making your own cob, or get someone with experience to make it for you.

Also, the cob is not JUST "a heat sink for the furnace".  Since the cob is the main thermal mass of the system, as it warms up (i.e., as heat is transferred from the stove pipe inside the bench to the cob), it will also work to keep the temperature of the stove pipe stable, even after the furnace has been shut down.  (I.e., the temperature of the stove pipe inside the cob will be the same along the length of the stove pipe.)

In your typical wood stove, the stove pipe leading outside to the chimney is not usually insulated.  This helps radiate some heat from the exhaust gasses as they leave the structure.  Since there is no insulation, the stove pipe will be warmer closer to the stove, and once the fire has been extinguished the stove pipe will reach ambient air temperature fairly quickly.

Most RMH designs I've seen (not all, but most) have the stove pipe inside the cob go from the furnace to the end of the cob bench, then make a U-turn and move back towards the furnace before exiting the structure.  Thus, as the cob nearest the furnace heats, it transfers heat to the stove pipe that is nearest to where the stove pipe leaves the structure.  I believe this means that the temperature of the stove pipe inside the cob, when properly constructed, will be SIGNIFICANTLY higher than the ambient room temperature.

To use your automobile engine analogy, I have no doubt you have a great deal of expertise in internal combustion engines.  However, the RMH is an Wankel combustion engine (think the original Mazda engines).  How much of your technical experience can be directly transferred from a four-stroke reciprocating piston engine to a four-stroke rotary engine?

marina phillips wrote:


1. I am deeply concerned that you have so much criticism for a system you refuse to learn thoroughly about. 

2. If you want to learn about something, do you not agree that it is best to go to the original source? 

3.The personal connection you have with "three stoves" is merely an interpreter of the information in the book, which is in its fourth printing.  If you want to avoid second hand information I suggest you buy the book. 

4. I'll say it again:  Beg, borrow, or steal the book.  It's a little more than $20, including shipping. 

5. Go ahead: break a system in to tiny parts, analyze those parts, and believe that the data about those parts yield more than the whole system.  This, in my opinion, is the fundamental flaw of modern science - the inability and unwillingness to study a system as a whole. 

6. I ask that you refrain from broadcasting your findings as a study of a rocket mass heater.  You'll be studying a partially built stove vaguely inspired by a rocket mass heater, and to report your findings as the scientific testing of a rocket mass heater would be misinformation vocalized. 

7. I believe these stoves have been safely used for about twenty years.  I hope for someone else with more concrete knowledge to back me up.

8. Sure would be nice if Ianto Evans or Leslie Jackson could join the melee and offer some defense of their design and design process.  I feel like it is them more than anyone else who is "on trial," so to speak. 

1. Uhm, doing an in depth study of it imho is not refusing to learn about at any level ma'am.

2. No, I would not agree with that, but I will agree it might well have merit and it is not outside the box.

3. I am completely unaware of where you were able to form the opinion I have any personal connection to 3 stoves, I do not think I have made any comment that should reference that at all. If I said anything that indicated this to you in some manner, it was not the intent. I have the luxury of coming to this completely blind to these products. While you see this as a detriment I can assure you it is not, it is a huge benefit, I have no vested interest in the success or failure and I can truly report unbiased data points.

4. I might buy the book, if nothing else your passion for it warrants a bit of inspection. Books cost me nothing but the time it takes to read them, when I am done with it I can donate it to the library.

5. I know a large number of scientist and none of them proceed in the manner of which you speak, nor do I. The cob may be touted to play an important role and it may be a lot of the appeal folks seeking to use environmentally safe, sound and renewable resources but it only serves two possible purposes, an insulating factor and a heat storage device. You may use it for sealing joints etc, I however will have no need to do so, what I build will have no leaks. I do not have the luxury of building it out of back yard type materials though I like the commitment to the recycle reuse efforts. When testing a device there are two categories of testing, destructive and non-destructive. While your unit may be more than adequate for a simple lack of terms, you have no idea how it will react under certain circumstances, Things you would never consider doing like coating the entire internal surface with a creosote simulating paste and setting it on fire without putting it out. When I say I am going to build "one" it means I am going to build several and I am going to destroy them, how else could I tell you the failure point?

6. The information provided will be any thing but misinformation, it will be data collected under controlled circumstances and a controlled environment. Misinformation reported about these heaters is exactly what has inspired me to perform testing upon them. I am not implying you have spread this information, simply stating a LOT of it exist on the internet and frankly there seems to be a lot more myths about these heaters than there are facts. I simply will be bring forward some factual data persons interested in them can use.

7. You do not need any back up on the 20 years, on the level playing field of space heating they would still be classified as an infant that was developed using technology that combines the very new and extremely old.

8. Wow, it appears you see me as an evil force seeking to destroy someone's life instead of a scientist whom is offering to tell you what it takes to make the heater fail so you can avoid such failures. No one is on trial except perhaps myself for not touting an untested and unproven space heater as perfect.

I saw your comments prior to the site owner editing for content on all of us. I am not sure that you do not remain suspect of myself because of my expressed thoughts on your comments. In defense of those comments, I do not think anyone would stay in a dangerous situation on purpose, nor do I think the family that passed on 12-11 this year would have said they thought their furnace was unsafe either if they had been asked on 12-10, it however was inspected by an incompetent professional in November.

I very much hope to PROVE a great many things, things like allowing it to repeatedly flame out will not allow explosive levels of fuel to build, when it back drafts because of the smaller chamber type toxicity levels will not rise above X amount within X cubic feet, more or less safety data points.

Despite thoughts to the contrary I have no desire to kill the concept or say anyone has done anything on purpose wrong or even that it is a bad idea. In many ways quite the opposite despite any other rumor.

Muzhik wrote:
By "failures" I'm assuming you mean having toxic gasses leak into the residence.  I'm not aware of any such events.  Can you document this claim?

FWIW, cob has an R value of 1. 

To use your automobile engine analogy, I have no doubt you have a great deal of expertise in internal combustion engines.  However, the RMH is an Wankel combustion engine (think the original Mazda engines).  How much of your technical experience can be directly transferred from a four-stroke reciprocating piston engine to a four-stroke rotary engine?

First point, it is documented on several of the boards dedicated to these heaters, it may be documented on this one. Has any one spoken here of their furnace puffing smoke out of the firebox? There are several references to it.

FYI cob does not have an R value of 1, that is not how it would be rated.

While I have been involved in building a few motors in my younger years that is not what I was talking about. I was speaking metaphorically. I have been involved in the heat transfer business on a multitude of levels working from the installation of, the repair of, the design of and the operation of these types of devices for almost 40 years. I have sought after certification of devices before, know what it takes, even understand a little of the politics. I now teach about these things and have access and the freedom to explore such opportunities.

I am about done with the fun and games btw.

RedNeck - is it possible for you to share the design you're going to use for the test *before* you build it so that folks here can critique it?  I know nothing about rocket heaters, but it seems to me that if you inadvertently chose a bad design with known faults, then it might not be the best test.  If, on the other hand, you tested a design that rocket heater 'experts' approve of, then it should be a much more interesting test from everybody's point of view.

I don't think there's a need for so much fuss.  NedReck is going to run some tests.  he'll perform them in such a way that his curiosity about rocket mass heaters will be satisfied.  maybe his tests won't be up to everybody's standards, but maybe we'll learn something anyway.

worst(ish) case scenario: an asteroid sets our atmosphere on fire and we all burn up horribly.

slightly better scenario: NedReck builds the thing wrong, declares rocket mass heaters horribly unsafe, goes on to publish papers about it and otherwise spread the word that these things are deathtraps based on testing of a bad design.  everyone who has posted about their own RMH gets a visit from safety inspectors and things go downhill from there.

those two seem unlikely.  other possibilities don't seem that bad to me.  maybe Ned will get it all wrong but we'll still learn something.  maybe he'll get it all right and discover a problem others haven't realized or encountered.  maybe he'll also find a solution to that problem.  maybe he'll completely change his mind about RMHs because his test model functions beautifully.

what seems to be the most likely outcome is that, regardless of the procedure or design, we'll all keep talking right past one another no matter the results and very little of substance will have changed.

run your tests, Ned.  if you want some input regarding designs that work well, do consider having a look at the RMH book or ask some questions.  I suspect you won't, but who knows?  I'm sure you could even download it for free from some unscrupulous internet villain, though you could also pay the $15 to do so legitimately.

Burra Maluca wrote:
RedNeck - is it possible for you to share the design you're going to use for the test *before* you build it so that folks here can critique it? 

Burra,

I have tried to make it perfectly clear repeatedly, I have never seen one of these stoves. While that does not leave me at a loss for how they operate, much to the disappointment of many, it really is not that complex at all and has a great deal of potential.

I seriously doubt there is any reason at all to continue bothering with posting here at all. I thought folks were looking to get the RMH tested, they are not, they are interesting in talking about why it does not get done.

They would spend their time more wisely by just beginning to build about ten of them since last time I ran something through that was indeed to minimum number of units required to begin the certification process. You may well find yourselves providing 2 or 3 times that many before it is over with and even doing so will only guarantee getting the test done, not passing it.

It is not really possible for me to continue discussing it further under the owners guideline of "be nice" and the philosophy he has backed that up with. IMHO it is counter productive and prevents the freedom of communication and all communication serves a purpose if even only to stand as a poor example. It is not possible for me to observe someone who is without any doubt 100% incorrect and then seek out words to only mildly indicate my opinion is different than theirs in a non offensive way. While he may choose to only seek out such types of persons, I find it counter productive to the learning process and surrounding your self with only people of similar thinking imposes huge limitations in what you shall be exposed to. Despite my disagreement with the core ideal, that does not mean I should not grant another the freedom to do so if they wish. That said, it only makes sense for me to take my exit from this board prior to bothering him or any of the others more than I already have as I shall not plan to be compliant at any level.

why don't you post about your results when you're done, NedReck?  you'll avoid having to censor yourself and still maybe save some of us dirty hippies from our silly stoves.  I'm sure you can easily get your internet argument fix over at the survivalistboards.  what do you say?

tel jetson wrote:
why don't you post about your results when you're done, NedReck?  you'll avoid having to censor yourself and still maybe save some of us dirty hippies from our silly stoves.  I'm sure you can easily get your internet argument fix over at the survivalistboards.  what do you say?

This is an example of exactly what I am speaking about. I have never referred to anyone as a dirty hippie nor have I said the stoves were silly. I have said some stoves I have seen were dangerous in design, I have also stated clearly that others were of very good design. Since it is deemed inappropriate for me to say you are wrong for making such a statement let alone describing how stupid I might feel it was for you to express such false things as fact as that would make you appear less than perfect, I can only thank you for expressing exactly why such restrictions are not a positive learning force.

The data will be provided for those whom seek it and the only loss will be that I will have less input on the beginning stages from those here with experience that will choose not to give that input elsewhere.

Peace and thank you,

Ned

I was shooting for a little self-deprecation, NedReck, not putting words in your mouth.  apologies for the misunderstanding.

and for whatever it's worth, Ned, I'm very curious about the results of your testing.

To clarify:

RedNeck is using the word "failure" in the sense of engineering jargon, not in the usual sense of the word.

If a nail "fails", it's because the builder didn't know its limitations: failure of one nail doesn't reflect badly on all nails everywhere, and recommend against their usage.

It sounds like the setup in question will produce interesting results, and will ultimately be good for the technology of rocket mass heaters. Everything has limitations, and my understanding, from these forums, is that the technology in question has a set of limitations that are broader than usual, and better-suited to a typical home heating task than, for example, a traditional fireplace.

Ladies and gents,

Please take the following information without offense nor feel as though it is targeted, pointing fingers, insulting or in any other way beyond what it is, simple information sharing.

I have no reviewed several drawings of these heaters. I said a few things that I clearly stated were concerns about the operation of them, all of them confirmed in several ways, but don't stop reading yet!

When I said they were prone to back drafting and spilling into the space, they are without any doubt.

When I said they are prone to issues with operation below the dew point, they do.

The list kind of goes on.

Politics are a fact of life. When it comes to research and testing or even the certification some folks desire for these heaters much more caution needs to be employed when talking about them. When persons educated in the field of combustion look at them and then pose questions that are fairly obvious, stating there are hundreds in use and it does not happen and it must not be true because you have never seen it undermines credibility completely and kills your efforts on the political side of things.

I say this because I had a paradigm shift while reviewing designs and saw great potential within these systems and how these obvious and known problems could be corrected and this was VERY exciting.

Please note I said known problems. I down loaded the pdf of the book today and read it. The issue of back drafting and spilling into the space, addressed in the book, documented that it happens in the words of Ianto Evans as well as being very self evident in pictures within. Condensate problems in the flue system, documented and addressed in the book, they are a problem. I would quote you the page numbers and paragraphs where he did so had I not left my jump drive in the computer at the college and I do not have the book with me at this instant.

Please again, no one take offense, I have a reason for saying this. When an obvious problem exist to the trained eye and one states exactly the opposite, the person with the trained eye is going to completely dismiss anything else you have to say as the ranting of the unreasonable. A very important portion of the sciences is critical thinking and if you are going to test something it is not a question of whether or not it WILL fail, it is what are the parameters under which it DOES fail.

Ianto Evans is without any doubt an interesting cat and I thank whom ever it was I previously spoke to saying their passions alone would make me buy the book, the statement had value that proved true. I do not know Ianto;s education level on the formal level, nor do I care. His understanding of the engineering within is very good and his ability to simplify it into common speak is fantastic, he would indeed be a very natural talent to be a teacher, he is in fact a teacher whether by occupation or not, his passion for it shines through and considering I have hired somewhere between 200 and 500 teachers in the last ten years, I may not know everything about what it takes to find the good ones, I know it when I see it without any doubt.

There are a few things in his book I shall discuss directly with him about, share my thoughts on improvement ideas on design to combat some of the issues and alert him to some of the hurdles that will indeed be required when seeking acceptance and certification of the design. Since he request critique and input I shall give it, however I will not do so in an open forum because such criticism was not invited.

Please again I  implore upon you, do not make statements that can be converted into false claims. There is more than enough of that available regarding these heaters to make anyone whom knows much about combustion vessels run with out adding any more. Lots of science types use the distorted version of Occam's Razor, "when all evidence is equal, the simplest is the correct" and as flawed a view as that actually is of Occam's Razor, it still applies. IF it looks like it will do X and the opposing thoughts weakly indicate it will not, it probably does X. This is a huge hindering thought process on critical thinking, but it does not make it less real.

Beyond that I am going to continue with my research on this project on Donkey's forum and hopefully have some interesting conversations with Donkey and Ianto in fairly short order. Will we solve all the worlds heating problems, no. will we discuss our thoughts and improve the design and possibly move closer to a design and proof of concept that might find consideration for approval? Who knows but that is my only goal personally.

Ned

the forum NedReck mentioned is here, by the way.

NedReck wrote:
Burra,

I have tried to make it perfectly clear repeatedly, I have never seen one of these stoves. While that does not leave me at a loss for how they operate, much to the disappointment of many, it really is not that complex at all and has a great deal of potential.

I seriously doubt there is any reason at all to continue bothering with posting here at all. I thought folks were looking to get the RMH tested, they are not, they are interesting in talking about why it does not get done.

Assuming you're the self-described cantankerous mad-scientist who is serious about testing, and not just trolling,

We look forward to seeing your results.  We hope they will be outdoors and appropriately safe for your students.

My husband Ernie and others are among the 'experts' who contributed to the book after participating in building dozens or hundreds of test systems.  I've been building these for 3 years now, and I still ask Ernie for technical details.
I can't tell from your postings whether you got a description from one of these experts (who may have 2-3 systems on hand), or from a relative novice who has built 2-3 systems in total.  We know of a few novice builders who mis-represent themselves as experienced teachers, but build systems that don't meet the basic design criteria, and such examples don't help the reputation of these devices.

Yes, anyone can build these wrong.  People who build their own modified version without reading the book, are the most common culprits.

Any solid-fueled system is likely to release small quantities of toxic smoke into the home environment, when operated by ordinary human types. And large quantities into the general environment, to be smelled by distant neighbors.  We are working to minimize both types of smoke. 
One of the primary safety features of any well-built masonry stove is that it does not need to be left burning unattended at night to maintain heat; thus, truly deadly smoke problems do not creep upon occupants unawares.  An unattended candle or lantern, or woodstove, has been proven unsafe repeatedly throughout human history, yet we use these devices routinely and safely with reasonable caution. 
The savings in wood fuel is a major factor motivating the development of these stoves, despite the technicalities of the open burn.  Operator competence may be a reasonable expectation of those who can survive on less, on a crowded planet.

My only suggestion about your water-jacket testing setup:
Our experience with existing RMH's: They heat cleanly when used regularly in winter, when the mass is warmer than outside air.  But a super-efficient model will be difficult or impossible to light cleanly when the mass temperature is below ambient air temperature.  There are several tricks in related threads for how to safely pre-warm or boost the draft of a cold stove.
To make it a fair simulation of heating conditions, I'd suggest you pre-heat the water in the jacket before lighting, or use a draft-boosting option to bring the mass up above ambient temperature just as a home operator would with a masonry version. 

If you have the lab experience and testing gear as you say, I am very interested to hear your results.  The only reason I can think that you would not want to refer to the general body of existing knowledge would be if you hope to re-design something 'better' and patent it.  If you do, please don't use the name 'Rocket' as it will be confusing, but best of luck.

A basic design and a few of the most important proportions can be found on our website at http://www.ErnieAndErica.info/rocketmassheaterpermitting

Please do your students a favor, and point them toward reliable resources.  Rocket mass heaters are different from rocket cookstoves, and some of the rules of thumb are quite different.  We can ship you a book, so can Cob Cottage Co http://www.cobcottage.com, or http://www.rocketstoves.com has the PDF as well as the print versions.

This thread is not the central place to discuss proposed modifications or DIY testing; try the "Rocket heater and butt-warmer" thread for more of this back-and-forth DIY detail.

This thread was launched to help fund-raise for independent lab testing.
Ernie and I operate on an annual budget of less than $15K most years, so we are limited in our own research to affordable materials. 
With outside funds, we hope to build an example heater at local EPA-certified OMNI-Labs in Portland, Oregon. The plan for best practice (and a proposed building code for these devices) is to use firebrick for the combustion core and perlite/fireclay insulation, but original RMH standard (reclaimed and earthen) materials for the balance of construction.

Hope that helps you find more useful information for your testing project.

Yours,
Erica Wisner

Erica Wisner wrote:
My only suggestion about your water-jacket testing setup:
Our experience with existing RMH's: They heat cleanly when used regularly in winter, when the mass is warmer than outside air.  But a super-efficient model will be difficult or impossible to light cleanly when the mass temperature is below ambient air temperature.  There are several tricks in related threads for how to safely pre-warm or boost the draft of a cold stove.
To make it a fair simulation of heating conditions, I'd suggest you pre-heat the water in the jacket before lighting, or use a draft-boosting option to bring the mass up above ambient temperature just as a home operator would with a masonry version.  

Ernie and I operate on an annual budget of less than $15K most years, so we are limited in our own research to affordable materials.  
With outside funds, we hope to build an example heater at local EPA-certified OMNI-Labs in Portland, Oregon. The plan for best practice (and a proposed building code for these devices) is to use firebrick for the combustion core and perlite/fireclay insulation, but original RMH standard (reclaimed and earthen) materials for the balance of construction.

Hope that helps you find more useful information for your testing project.

Yours,
Erica Wisner

The cold start is certainly a problem that exist,  however, I am fairly sure it can be overcome, well I know it can be overcome but my goal is not to modify it in such a way that you could not. In other words it needs to be done in such a way that does not involve anything more than a commonly discarded item one might find at any hardware store or if they posses the talent field manufacture using hand tools only. Best said, high tech workings from low tech parts.

Budgetary issues are of no concern for a small project like this to me or my departments, most of the high tech stuff the students are using now have controller boards that cost more than these stoves including a bit more industrial version I have in my mind to construct to confirm the fluid dynamics taking place inside the core unit. I do not plan on taking the start up temp below 32 initially so water is fine, if it is determined that feasible operation lower than that (aka in a vacation retreat that might be -10 on arrival and start up) and I can load the cooling tower through about 100 degrees.

From purely my own perspective, its not ready for testing yet. The experience you are having with them more or less not quite knowing what to call it is not a huge surprise. There are a lot of regulations surrounding how the combustion gases are handled. Having not seen your design I can not speak directly to it however, I can pretty much say that it violates several of them. In tech speak that would indicate it can not operate safely by established standards. With that thought in mind, the operation of it has risks and does need to be tended to and if it is, I would agree it is pretty low risk and as has been indicated, if one depended on the cob battery for heat when the unit was not in operation, any malfunction of operation would be noticed by the operator and easily corrected. Unfortunately it is a well established fact that there are indeed folks whom are not too bright in the world so when standards are developed a lot of the regulations come from “idiot proofing” the equipment.

I have no interest what so ever in seeking a patent. If Mr. Evans returns my call and we begin to communicate freely about it, we might be able to do some things that would improve the range of performance, widen the sensitivity to fuel, and provide the proof of concept in a fairly “idiot proof” manner. If he chooses to seek a patent, that will be his choice, some how from his writing in the book, I do not expect that is a goal of his either, though he might do so just to keep the technology free or very low cost (the price of the book) as a personal improvement to the world we all live in. My motives on the other hand are more selfish. As I said before, I am an INTJ personality type, I come alive when my mind is challenged and I have basically no creative side what so ever, mechanical thought is so intense for me I literally lose track of time. I can’t really explain it because I can not comprehend why all people are not this way as stupid as that sounds. I HAVE to know HOW this thing works and WHY it works that way to the point of obsessive compulsive behavior. I have likely slept under 10 hours total since I first signed onto this board.

I hope the energy I put into it helps you and others advance this in whatever manner you see fit, I seek only the stimulation it provides my brain and once I am convinced I have it pretty much all hammered out, I will indeed drop it like a hot rock and seek out another project to tax my mind. When I said mad scientist, you likely have no idea to just how close that really is.

Good luck in your efforts,
Ned

NedReck wrote:
The cold start is certainly a problem that exist,  however, I am fairly sure it can be overcome, well I know it can be overcome but my goal is not to modify it in such a way that you could not. In other words it needs to be done in such a way that does not involve anything more than a commonly discarded item one might find at any hardware store or if they posses the talent field manufacture using hand tools only. Best said, high tech workings from low tech parts.

My favorite tool for the cold start is a candlestick under the heat riser, others prefer a priming hole in the (final) chimney to start on secondary draft.

NedReck wrote:
Budgetary issues are of no concern for a small project like this to me or my departments, most of the high tech stuff the students are using now have controller boards that cost more than these stoves including a bit more industrial version I have in my mind to construct to confirm the fluid dynamics taking place inside the core unit. I do not plan on taking the start up temp below 32 initially so water is fine, if it is determined that feasible operation lower than that (aka in a vacation retreat that might be -10 on arrival and start up) and I can load the cooling tower through about 100 degrees.

Where is this department with the unlimited budget that wants to test rocket stoves?  Can I crash the party and get some data?

NedReck wrote:
From purely my own perspective, its not ready for testing yet. The experience you are having with them more or less not quite knowing what to call it is not a huge surprise. There are a lot of regulations surrounding how the combustion gases are handled. Having not seen your design I can not speak directly to it however, I can pretty much say that it violates several of them. In tech speak that would indicate it can not operate safely by established standards. With that thought in mind, the operation of it has risks and does need to be tended to and if it is, I would agree it is pretty low risk and as has been indicated, if one depended on the cob battery for heat when the unit was not in operation, any malfunction of operation would be noticed by the operator and easily corrected. Unfortunately it is a well established fact that there are indeed folks whom are not too bright in the world so when standards are developed a lot of the regulations come from “idiot proofing” the equipment.

Yup.  Babies can't escape a millipede, let alone a house fire.
(Most children by the time they can reach high enough on a RMH to get burned, are at least as intelligent as the proverbial housecat.  But some people work very hard to avoid learning common sense.)

If the local building inspectors and EPA inspector can get all bright-eyed and wistful about it, I'm willing to take it to the next level and see what the bosses think. 
There are a lot fewer ways to hurt yourself on one of these than a woodstove, but I agree the smoke containment is likely to be the big issue.  Earthen masonry and scrap metal in this configuration is weird, but not overtly dangerous.
Still looking for that perfect combination that retains the self-feeding, easy-tending operation for us smart folks, but adds a little easier smoke containment for the newbies.  Like how people will operate an insert or fireplace with the glass doors closed until they get comfortable enough to realize that they get more heat with the door open.  You'd have to see one in operation to understand the problem and why I feel it's worth improving on this rather than starting over.

NedReck wrote:
I have no interest what so ever in seeking a patent. If Mr. Evans returns my call and we begin to communicate freely about it, we might be able to do some things that would improve the range of performance, widen the sensitivity to fuel, and provide the proof of concept in a fairly “idiot proof” manner. If he chooses to seek a patent, that will be his choice, some how from his writing in the book, I do not expect that is a goal of his either, though he might do so just to keep the technology free or very low cost (the price of the book) as a personal improvement to the world we all live in. My motives on the other hand are more selfish. As I said before, I am an INTJ personality type, I come alive when my mind is challenged and I have basically no creative side what so ever, mechanical thought is so intense for me I literally lose track of time. I can’t really explain it because I can not comprehend why all people are not this way as stupid as that sounds. I HAVE to know HOW this thing works and WHY it works that way to the point of obsessive compulsive behavior. I have likely slept under 10 hours total since I first signed onto this board.

Mr. Evans is not doing active research and development on these any more - calls tend to get passed on to me and Ernie quite a bit, or to a couple of other researchers down in California, depending on where the caller is from.  So don't be hurt if he never does respond.  You're right, he's not interested in a patent; he's developed a strong aversion to governmental agencies of many kinds, and to idiots.  I suspect he kind of likes it that if you don't tend the fire, or clean out the stove, it smokes back at you.  He did a lot of work in places where the ladies have been cooking over indoor twig fires and inhaling the equivalent of a 400-pack-a-day cigarette habit in indoor smoke.  He's been heard to predict that if we all just ignore the building code folks and refuse to cooperate, the whole thing will collapse under its own weight.  He runs annual courses on how to 'get off the treadmill' and stop buying into the mortgage/debt/employment lifestyle.

But he grudgingly tolerates Ernie's and my attempts to wrestle with the lesser angels of building officialdom, and open a path for tested, coded, and permitted installations of these systems.

Ernie is working on computer modeling for the fluid flows.  He could use some help, if that's your thing.  He's already heated test models to white-hot with illicit fuels, and attempted to build a half-model with an expensive and short-lived piece of Pyrex glass, as well as building hundreds of variations in more ordinary ways to try to replicate and develop remedies for the most common problems. 

He's working with open-source software on our budget, building a wireframe and then going to run a fluid-flow through in another program to see if it can approximate the real results.  I think we're surfing some aspects of fluid dynamics that are just not employed in most combustion devices, and I personally don't have a lot of confidence that the programs will have the right fluid dynamics on tap.  I've seen the troubleshooting of commercial HVAC systems, and I don't think the state of the art is that impressive when it comes to small pressure differences.  Maybe there are some science models that haven't trickled down to industry yet, or something that came out recently to advance CGI animation.

I'm working more on the social compromises: just how easy does it have to be, for an early adopter to get interested?  How much fuel savings, and how much convenience, will it take for the idea to progress beyond those early adopters? 
What is the most likely tragedy, and how can we mitigate it?  And will our efforts pan out and allow us to make a decent living, or are we going to be stuck  in 'maybe someday' forever, outmaneuvered by rival factions in the dazzling world of big building business?

NedReck wrote:
I hope the energy I put into it helps you and others advance this in whatever manner you see fit, I seek only the stimulation it provides my brain and once I am convinced I have it pretty much all hammered out, I will indeed drop it like a hot rock and seek out another project to tax my mind. When I said mad scientist, you likely have no idea to just how close that really is.

Good luck in your efforts,
Ned

Thanks for your good wishes.
Maybe that's why we're in it too: it's a puzzle, so weird and so much potential, and I want to see how it turns out.

I hope that actually seeing one burn gets you hooked thoroughly, enough to nail down some of these parameters before you find the next monster to reassemble.

The water-jacket test would be most useful if you are willing to run it on a system with otherwise normal proportions - it would be immensely helpful to have results that could connect our hands-on 'acceptable' performance with the standards for other combustion devices.  How does it behave within the normal acceptable limits for house air pressure, for example; a wind gust can puff smoke down almost any chimney, but we can approximate other devices' draft by sacrificing some of the effciency for exhaust heat and secondary draft.
Another useful tidbit would be to get some numbers on how cob absorbs heat so we can compare it with soapstone, concrete, etc. A lot of people try welding variations together, or want to build one of these with concrete, and I think they're in for unpleasant surprises if they don't account for the differences in density and heat conductivity.

Speaking of no sleep, I better wrap this up.
Check out the book, or visit the website, and I'll be posting the second draft of the code soon for comment.

-Erica Wisner

Please remember the less than perfect personality that is responding for what it is and realize that there is no ill intent contained within. Reposonses will be ... inserted.

Erica Wisner wrote:You'd have to see one in operation to understand the problem and why I feel it's worth improving on this rather than starting over.

...Actually, I promise this is not required. I have studied the operation from many angles and am about 99.9% positive I have a fantastic visual developed from reviewing working designs, known failures and why those minute changes caused the failure. Fixing some of them is not as hard as one might think, but others may indeed prove to be very hard to eliminate.

Mr. Evans is not doing active research and development on these any more - calls tend to get passed on to me and Ernie quite a bit, or to a couple of other researchers down in California, depending on where the caller is from.  So don't be hurt if he never does respond. 

... With a grin I can assure you I will not be unhappy if Mr. Evans opts not to contact me. A lot of folks tend to change a lot while online, I am not one of them, I am just as hazardous in real life and there are more than a few whom consider my company unpleasing. While it might not be his reasoning, it happens enough I am quite used to it, I offend folks without intent and with intent both. I know "Donkey" has figured out a method to be tolerant of my misgivings and his wisdom and honesty have been quite helpful. If you and Ernie are capable of such tolerance, I am not opposed to discussing it with you as well.

You're right, he's not interested in a patent; he's developed a strong aversion to governmental agencies of many kinds, and to idiots.  I suspect he kind of likes it that if you don't tend the fire, or clean out the stove, it smokes back at you. 

... LOL Government is cool! It is a fantastic idea that has become distorted in so many ways the intent gets lost. Originally it was designed to protect us from itself and now it protects itself from us. Since I love ironic humor, I tend to get grand entertainment from the government machine all the while despising its existence.

He's been heard to predict that if we all just ignore the building code folks and refuse to cooperate, the whole thing will collapse under its own weight. 

...I tend to disagree a bit. Nothing a power monger likes more than attention and if you fail to feed it, it tends to seek out more negative ways to get it.

But he grudgingly tolerates Ernie's and my attempts to wrestle with the lesser angels of building officialdom, and open a path for tested, coded, and permitted installations of these systems.

... I have driven a few things through certifications and understand a bit about it, most of it is really kind of stupid, some of it make sense.

Ernie is working on computer modeling for the fluid flows.  He could use some help, if that's your thing.  He's already heated test models to white-hot with illicit fuels, and attempted to build a half-model with an expensive and short-lived piece of Pyrex glass, as well as building hundreds of variations in more ordinary ways to try to replicate and develop remedies for the most common problems. 

He's working with open-source software on our budget, building a wireframe and then going to run a fluid-flow through in another program to see if it can approximate the real results.  I think we're surfing some aspects of fluid dynamics that are just not employed in most combustion devices, and I personally don't have a lot of confidence that the programs will have the right fluid dynamics on tap. 

... Yes, I can indeed be helpful in more ways than one. The computer department head does not object to my ways and we both despise the political arena we work within at times. You are 100% correct in your assessment of combustion devices, I will expand more in a private manner only. I think you are mistaken in the programs abilities, like anything else with 'puters, input good, output good, input bad output bad. If my thoughts are correct which I have arrogantly already stated I think they are, it would be very easy to input poor data. I do not know Ernies "level" of education in these processes and when I speak to "level" it has little to nothing to do with formal education and everything to do with understanding.
 

I'm working more on the social compromises: just how easy does it have to be, for an early adopter to get interested?  How much fuel savings, and how much convenience, will it take for the idea to progress beyond those early adopters? 

... This "widget" offers nothing. Technology that fuels the capitalistic incessant need gets attention as it allowed one to take lots from others. Since it is simple to replicate, no matter how complex its fundamentals are, there is no effective way for one to capitalize upon it. Since it does more with less, it is indeed contrasting to capitol development. As stupid as it sounds, none of the industry that is involved would have any interest, it does nothing but reduce their capitol interest.

What is the most likely tragedy, and how can we mitigate it?  And will our efforts pan out and allow us to make a decent living, or are we going to be stuck  in 'maybe someday' forever, outmaneuvered by rival factions in the dazzling world of big building business?

...Depends on what a "decent" living really is doesn't it? In some distorted manner by and large this has come to mean "have more to feed more that have the most" which is a redundant double negative in my personal opinion.

I hope that actually seeing one burn gets you hooked thoroughly, enough to nail down some of these parameters before you find the next monster to reassemble.

...I do not need to see one, nor do I need to be "hooked" I am beyond that already. Please excuse the language, but this is some really cool f*** stuff!

Another useful tidbit would be to get some numbers on how cob absorbs heat so we can compare it with soapstone, concrete, etc. A lot of people try welding variations together, or want to build one of these with concrete, and I think they're in for unpleasant surprises if they don't account for the differences in density and heat conductivity.

...The cob really does not play an important role in the operation. It is a thermal storage device, a thermal battery if you will. Now when I say it does not play a role, that is not discounting it at all. Think of an electrical battery. They have a rate, a rate one should charge and a rate one should discharge. The cobs role may be best stated as a regulator of sorts. Instead of controlling the "voltage" going to it, the cob controls "how much voltage CAN go into it" which may buffer the processes taking place, I do not discount that at all. If I am correct, they would need regulation as they are very sensitive to change and the cob may very well "insulate" the process from those changes, obviously not in the terms of insulation typically understood such as keeping the heat in or out.

Speaking of no sleep, I better wrap this up.

-Erica Wisner

I intend on sharing more and will give the path privately.

Professor-

I'll start by thanking you for your efforts- i cringe when folks say things like, "you clearly don't care enough to" or "don't know enough" or whatever to people they've never met or gotten to know.

For my part I've started playing with these recently- managed to melt an aluminum j-tube in short order, and have now done a handful of brick and metal models- even got in trouble at my own school when a student in our sustainability program said the rocket stove demo was " a good idea" but complained about my lax safety standards. I don't suppose it'll be much help to show them youtube vids with folks working in sandals... sigh...

Anyway, regardless of the naysayers and skeptics, do what you're doing, and share as much as you can, and if you don't want to share it here, share it somewhere else (including to my email di@gdwell.org) . Like Paul, I want to build a portable version, which makes the cob harder to manage. Like you, I would feel more comfortable with a more "precise" plan- worried less about specific costs and more about exactly how many cm such and such an opening should be to get it right - and damn, those 25gal barrels are hard to find- in metal!

Keep it up.

And for the record, I bought the PDF, and the hard-copy - but only after playing around and reading a lot first!

icky

ps- when my first simple rocket stove (aluminum duct jtube inside bigger tube with ashes in middle) melted, a friend watching (who has his own foundry) said, "You know, aluminum melts at 1000 degrees." I asked, "Why the *)(*)U didn't you tell me that while i was building the thing? " He said, "I figure you'll never forget now..."

pps- apologies since this really is the wrong forum- just responding to what's there.

well, now that everyone has chipped in about the technical details of how NOT to build a rocket stove...

anyone interested in seeing the current, inventors'-best-practice model put through some EPA tests?

I looked into the Kickstarter website, they say it's not a good fit for their site but good luck.  Maybe we'd get farther with the how-to video we're producing, they seem to cater to arts projects.

The test I most want to see is how clean is the exhaust on a 'normal' system.  We might be able to add 'modular' lengths of thermal mass to test several variations on the same system. 

The second test I'd like to see is some data to figure out exactly how thick the cob should be, or an alternative masonry unit like bricks, if you are going to run the thing all day and have cushions on it. 
Our experience is mostly with stoves that are run 2-6 hours per day on average, and where somebody removes the cushions if it gets too hot.  Thicker masonry mitigates the 'hot spots,' but it is still possible to overheat a system if you use high-value fuels.

Another test I'd like to see would be what strength is the draft under 'normal' conditions, and what range are the safe operating temperatures of these stoves.  Ours works well when the thermal mass is warmer than outside air, but we have problems with a 'cold start' on a hot day.

How long a heat exchanger would be allowable and still keep the exhaust above dew point at the chimney?
Would a bypass chimney-warmer be sufficient to promote good draft and prevent smokeback?


-Erica Wisner

...inserted responses

Erica Wisner wrote:
well, now that everyone has chipped in about the technical details of how NOT to build a rocket stove...

anyone interested in seeing the current, inventors'-best-practice model put through some EPA tests?
... very much so and I hope the upcoming efforts can provide enough proof and interest to get just exactly that done along with performance curves.

I looked into the Kickstarter website, they say it's not a good fit for their site but good luck.  Maybe we'd get farther with the how-to video we're producing, they seem to cater to arts projects.

The test I most want to see is how clean is the exhaust on a 'normal' system.  We might be able to add 'modular' lengths of thermal mass to test several variations on the same system. 
... the less expensive equipment used in standard tuning methods is fine for a close estimate, the problem does not revolve around that, this issue applies to lowering the exhaust temps too far, at that point the reliability of the software driven equipment fails to be accurate as it is not designed to operate outside of its parameters and there is a curve to its accuracy, if you get outside that curve, it is simply unreliable.

The second test I'd like to see is some data to figure out exactly how thick the cob should be, or an alternative masonry unit like bricks, if you are going to run the thing all day and have cushions on it. 
Our experience is mostly with stoves that are run 2-6 hours per day on average, and where somebody removes the cushions if it gets too hot.  Thicker masonry mitigates the 'hot spots,' but it is still possible to overheat a system if you use high-value fuels.

...though not on my to-do list, a thermal conductivity test on cob would answer this question, I do not think you will ever get rid of "hot spots" and would offer that this will always depend upon the materials and percentages used as well as the experience of the cob mason applying it. All the math capabilities and understanding in the world at my finger tips would not likely render as consistent or quality results as persons whom have made several of these and have developed a "feel" for the application.

Another test I'd like to see would be what strength is the draft under 'normal' conditions, and what range are the safe operating temperatures of these stoves.  Ours works well when the thermal mass is warmer than outside air, but we have problems with a 'cold start' on a hot day.

... If my two of my theories on operation are accurate, this would be because of the density of the air affecting the engine that drives it as well as the thermal prime mover involved in acceleration of the gases through expansion, simply put the hotter the air the more it expands the more rapid the velocities, the warmer the air entering, the less the expansion itself becomes. this is why they operate over a narrow range and why if we define the parameters on it I think we can expand the range significantly with some fairly simple design alterations.

How long a heat exchanger would be allowable and still keep the exhaust above dew point at the chimney?

... This is hard to develop without a bit more info, one being accurate information on the pressures and after that, in order to keep it within the range of operation for approval, this number will be much higher than many folks want to hear. I can certainly prove that number for X temp at X relative humidity at X firing rate with X percent water content wood, but as soon as any one of those X's changes, the dew point will change as well. If you want to get a ball park for your own personal unit, take a good thermometer and cover the bulb completely with a cotton ball, wet the cotton ball with distilled water and put it into the exhaust stream for 5 to 10 minutes.

Would a bypass chimney-warmer be sufficient to promote good draft and prevent smokeback?

... I do not have a good answer for this one at all. I have an idea that might prove effective but I am not sure I could recommend it until we have found the range of operation and expanded it a bit as my thought is going to lend itself to effecting operation of the stove as I understand it and with my thoughts on the theory of operation, it might impact it a lot in a negative way. Would be a real pain to make one only to have done so in such a way it will not fire off the secondary burn.



-Erica Wisner

On 12-27-2010 a lot of stuff happened at work and as the administrator for 50% of the school, it has just thrown my professional life into turmoil through 3-5-2011 and then it should calm down, Time in court, issues issues etc have just rendered me furious. It is supposed to be about learning and teaching but right now it is about politics and protection, both of which I find to be flawed as they are based in dishonesty. Without regard for my own positions on such things, I am bound by my own commitment to my student population to be sure the outcome is best for THEM, not the school or anyone else, just the students.

That said, in about 30 days this project can once again hit the table and start gathering data. I can honestly state without any doubt, I would much rather be proving myself totally wrong through experiments on these units than I would doing what I have done since the beginning of the year.

Because of you guys experience with these units I once again would like to invite effective communication of findings in my lab and your real world experiences, my only stipulation is that until we have proven our findings effectively, it not be done in the open and once those findings are indeed proven they be made free for all in the public domain. Not only does it speak clearly to the spirit under which they were developed, it will provide a clear path one can choose to reduce their impact upon the environment through education instead of capitalism.

Prof. Rich.

I'd just like to pop and and say thanks for keeping talking long enough for folks to realize you're here to give us a boost
I'd love to volunteer some time in you're lab but I'm sure you're students are all better qualified than me, Can't wait to read the paper(s) when you have your data and are ready to publish.

Ernie
I'm on a student budget but I think I can find $50 for your testing fund next week how is it going?