Rocket Stove Thermal Mass Heater Technical Advice Wanted

There is a thread going on at:
http://www.survivalistboards.com/showthread.php?t=141190
where several technical engineering criticisms are made concerning the Rocket Stove Thermal Mass Heater.

Are there any engineering types here who could go over there and  respond to them?

I'm not technical enough to argue with him.  After reading what he's written, he seems to be focusing on two things:

1. it is impossible for a RMH to be have sufficient draft to allow the combustion products to leave through the chimney;

2. it is impossible for a RMH to prevent carbon monoxide and other combustion products from leaking into the living space.

He seems to have decided that it is impossible, and that anyone who builds a RMH needs to have their will drawn up because they've just built a suicide machine.

The only solution I can come up with is to make sure we donate enough money to be able to run the lab tests needed to show a RMH is both safe and efficient.

Well....no one's died in our yurt.  We plan to get a carbon monoxide detector, just to be sure.  An infant slept in there last month.  Apparently we weren't worried, and shouldn't have been, because she's still alive and well. 

I'm not sure a lot of people at this board are willing to go argue with someone who seems to have made up their mind about the issue already - without having seen a stove of this sort in person or experienced the way they burn wood.  I'm certainly not interested. 

In re-reading his messages, particularly where he describes the modifications he'd make to make a RMH safer, it's clear the only way he thinks it would be safer is to turn it into your typical RMH into your typical wood stove.

I will say one thing about one of his points, and that's the source of the air used in combustion.  One good thing about your setup in the yurt is the burn chamber is outside the living space.  This means that none of the air you're breathing would be used by your furnace.  If you're building a RMH in a super-insulated house (which usually means a very "tight" house) the source of your breathable air is a serious concern, ergo the use of "air exchangers" to ensure the sufficient flow of fresh air into the structure.

If/when I get to where I can build a house with an RMH, I'm going to make sure there is a pipe running from the outside into the burn chamber in order to ensure that as little of my breathable air is used in combustion.

HIM = Me

I would like to make some things perfectly clear.

1 I did not come here to argue at any level, I am unfamiliar with the forum, have little interest in researching who likes to fuss and who likes to learn so if your a fusser, know now I have been on the internet since the days of bbs systems and graduated to usenet, I can ignore anyone.

2 The discussion stems from ONE specific "rocket stove mass heater" not all designs or stoves.

3 My issues regarding the "concept in general" surround the misguided claims such as 90% efficient, 0 to near 0 emissions, etc.

4 The extraction of heat from the flue system (post stove/furnace) on a natural draft appliance such as the warming benches and the buoyancy, flow rate, turbulence and pretty much every other aspect of fluid dynamics.

5 The well known warm up times of similar designs, the poisons in flue gases (not just CO), chronic exposure issues and destructive properties of the flue gas components.


6 the below dew point flue temps that allow these products to precipitate out of the flue gas and condense in various locations through out the entire system.

I do not expect to spend much time over here, I have other priorities and I have already spent far more time on the subject than I really cared to. While I have already been accused of having my mind made up, I find the reverse to be true and small parts of different concepts and proven theories have been touted as fact when very important details were ignored.

I have quickly browsed this forum and saw one design that includes a warming bench looking item with a shelf (I think it said dehydrating shelf, I simply do not recall) and assuming the flue was properly taken off, it may well be a very good and safe design for a heating appliance. I have done none of the math to confirm, but at first glance it does not have significant problems to impede flow as other designs do.

Despite the feelings and thoughts that this is a really fantastic design and it is so simple anyone could build, IMHO there are far more effective ways to heat the space without some of the issues that design imperfections of this style and concerns from those imperfections produce.

That said, feel free to discuss or flame, I care not either way.

I didn't read all the posts on the other site , but I have one issue with RMH designs. The vertical 'chimney' is creating a positive pressure on the rest of the system down stream. So, great care must be used to maintain an airtight seal on that part of the system in order to prevent combustion gasses escaping into the living space.

Philip Freddolino wrote:
I didn't read all the posts on the other site , but I have one issue with RMH designs. The vertical 'chimney' is creating a positive pressure on the rest of the system down stream. So, great care must be used to maintain an airtight seal on that part of the system in order to prevent combustion gasses escaping into the living space.

That is a given in ANY HVAC system.  Leaky air ducts in the US are responsible for wasting enough energy to power the houses in California.  Even if it's the tube that runs straight from the pot-bellied stove to the roof and outside, it needs to be sealed.

let's stick to the topic at hand, folks.

NedReck: I think your technical knowledge would be very much appreciated around here supposing you tone things down a little bit.  you were presented as the villain from the get go, so maybe you're not entirely to blame.  and your history with the internet is fascinating, but let's talk about heaters instead.  what do you say?

regarding flue temperatures: is that mostly an issue of getting the gases out of the flue?  does the exit temperature still have to be so high if the flue is horizontal and gravity won't work against colder flue gases?

toxic gases: is CO a good indicator for the others?  which is to say: would a CO monitor effectively test for other toxic issues as well?

fluid dynamics: very complicated stuff, I'm sure.  many of these things (rocket mass heaters) have been built and are working very well; some have been for a good long while.  seems pretty likely that some have been built that completely failed to work, as well.  I hope nobody was poisoned by them.  I'm not familiar with the particular stove NedReck has concerns about, so I'm not in any position to say the concerns aren't valid.  neither am I very knowledgeable about fluid dynamics, et cetera.  I do know that technical expertise isn't the only way to arrive at a solution.

unsubstantiated efficiency/pollution claims: to be honest, I think you've got us there.  it's my belief that a carefully designed and built rocket stove can be one of the more efficient and less polluting ways to heat with wood.  maybe not the very cleanest or most efficient, but I think they compare well, especially considering the relatively low price.  I haven't seen anybody on here claim 90% efficiency, but it wouldn't surprise me at all to find that figure being thrown around elsewhere.  I wish this failed thread had gotten some action.

NedReck: if you think you can avoid being confrontational, there's a reasonable chance you could get yourself invited to see one of these things work.  would that interest you at all?  you would probably have to promise that your attitude in the meat world would be better than your attitude on these here internets.

tel jetson wrote:

NedReck: if you think you can avoid being confrontational, there's a reasonable chance you could get yourself invited to see one of these things work.  would that interest you at all?  you would probably have to promise that your attitude in the meat world would be better than your attitude on these here internets.

Life teaches one a lot of lesson and one of the lessons I learned long long ago is to never promise something you might not deliver, the disappointment level felt by others is ten times worse than if you never promised at all.

To give you a little insight, I am an INTJ personality type to the 95th percentile, that means I basically do not care about rules and by my very nature I am confrontational. I am also not without humility and a very in depth self questioning and internally suspect of myself pretty much at all times as I am of others. If you want to google up the personality type, you might find it of value when trying to interpret my blatherings which at times are quite questionable in nature.

As far as the furnace goes, I have indeed decided to build one in my lab. Some folks have to be asked nicely, some folks have to be curious and some folks have to get a little annoyed in order to get motivated sometimes. Asking me nicely really does not help but if I am curious about something and I get pissed, I have to prove it out so I get off my butt lol.

You have the link to the thread on the other forum, you are invited as is anyone to participate there, it is nothing about this forum, I just only have so much time and I have put a lot more information there already as well as having been offered a "working" design to scale in my laboratory.

If you or anyone else feel that my fundamental overview of the RMH is incorrect, feel free to comment on it and correct any misgivings.

Ned

PS the reference to hippies is not a negative, A lot of what is wrong in this entire world is the way we live. The Indians hunted, fished, camped, hiked, sat around the fire, talked to their children etc. Now I work 48 weeks a year to do that stuff 4 weeks a year. The rest is all an illusion we fabricate. No offense intended even when pokin a little fun, I am aware I am a much better target

seems like the cats were sleeping on it. dint see much else looking like baby roasting in that thread. Still not sure Ned isnt confusing his facts.

cats. cant imagine a better canary in the coal mine, so to speak- cats are almost on level with us in the CO2 mix requirements department, and alot more sensitive to changes than we are. In fact, cats note changes in CO2 density with about 2x the acuity we do (still far less than dogs), and unlike us they have a pharyngeal response to it- that means their throat muscles and olfactory nerves react to Co2, unlike us, excepting at dangerously high concentrations when some folks report a sharp metallic smell. right before gasping and falling over dead.  It is a possibility that cats can actually smell CO. So cats sleeping up there is a strong indication of a pretty airtight system. and one that is moderating its heat well.

Deston Lee wrote:
seems like the cats were sleeping on it. dint see much else looking like baby roasting in that thread. Still not sure Ned isnt confusing his facts.

it's a new stove and maybe the owner is busy.  some day she'll get around to roasting some cute tykes.  they're not so clever as cats.

NedReck wrote:
You have the link to the thread on the other forum, you are invited as is anyone to participate there, it is nothing about this forum, I just only have so much time and I have put a lot more information there already as well as having been offered a "working" design to scale in my laboratory.

If you or anyone else feel that my fundamental overview of the RMH is incorrect, feel free to comment on it and correct any misgivings.

Ned

browsed it briefly.  that's a pretty serious shit show going on over there.  if you're interested in a more civil exchange, stick around.  your demeanor is improving already.

tel jetson wrote:

1.what appeals is not wading through pages of crap to find the good stuff. 

2.  if it will help, I can call you a tactless moron periodically to keep you going over here, NedReck.

3. anyhow, what about stoves?  anybody braver than I want to traipse through that survivalistboards thread and address some of the issues here?

1. uhm, might seek out the local library as the internet is pretty much nothing but an exercise in wading through the crap to find the good stuff.

2. I prefer "walkin, talkin, moron" but you have to try and impersonate the guy in animal house "ya moron" there is just something about saying it that way that ads a little edge.

3. Delegation already? we just got started!

Perhaps we shall call you kitty, you know using that little girl voice from Pepe LePew!

stoves, Ned, we're interested in stoves.

I deleted about a dozen posts.    Which is a drag - not only does it take a fair bit of my time, but there was some otherwise good content in those posts. 

Quick refresher:

be nice

State your position without suggesting that anybody on permies.com is anything less than perfect.

If you see something less than nice, please don't add to the heap of less-than-nice-stuff.  Instead, click on "report to moderator" and there is a good chance I will pop in and delete it.

If wanna talk about what I jerk I am for deleting stuff, probably best to take that to the tinkering forum. 

A bit of a drive-by posting, but you should find it helpful.  The Aprovecho Research Center has a lot of publications available.  (Which, considering they invented the rocket stove concept, is unsurprising.)  Quite a few of them discuss CO emissions, though I didn't look through them enough to see if any other gases have been examined.

If you are interested, a companion technology is 'ceramic water filtration', which can be made out of nothing more than clay and coffee grounds, yet is efficient enough to remove even cholera.

The very best point I noticed within the publication including RMH relating to this discussion:

"Inventor’s pride has steered the wagon on more than one occasion here at
the research center. Inventor’s pride is amazingly powerful and difficult
to guard against. That’s why we like to have other people test our
inventions. An inventor may be unable to keep from influencing the
testing process. Getting impartial testers to critique a stove is
exceptionally helpful and creates a more appropriate technology."

It is my intent to serve in that capacity, nothing more and nothing less.