Rocket Stove Certification

[chronictom]

Well, in some cases, it's because certain people travel around to different sites and attack people on general principal in snide manners, and then try to act like the other person is at fault for doing it.

In other cases, it's simply a matter of people not being able to communicate effectively though text alone. The majority of real communication, is non verbal (or text), as in facial expressions, tone, and body language. Combine that with people's expectation that they know everything, and it ends up with serious conflicts over nothing.

And in yet other cases, it is a matter of people believing that they (generally through their experience), know more then anyone else and when disagreed with, they become defensive. That is the part that was referred to earlier as the 'blinding of oneself'.

And then there are people like me... who have become 100% fed up with people either getting involved in other peoples lives when they don't have any reason to do so (read 'codes' into that) other then a desire to show that they are right, or in people suggesting that their experiences watching, reading or hearing about, is the equivelant for other peoples DIRECT experience. IE, the person who says, oh sure, you SAY it works for you, but what facts do you offer to prove it...

[jpmanley]

"Our approach was to certify the heater builder, so we developed a certification program complete with an educational program, including our heater builders manual, and final exam for the certification. "

Your own statement answers your own question... imagine that;

"I am curious though, who are the people, and where are the places that have mandated that you have to have a license to build a heater"

<JP..The certification program, among other things, is also our attempt to educate masons so that they can build a better and safe heater.
Who said anything about licences, except you? There are no licences involved here. No laws anywhere says anyone has to have a certified heater builder build their heater. Anyone is welcome to build their own heater if they like (and as I said but of course you ignored), I encourage people to do it themselves. But to do it well and safely.>

"like where I live in Maine the firebox needs to be larger, so more wood is consumed, more heat is produced, more channels are added to absorb more heat, the more it begins to look like what we call a masonry heater."

Or you find a way to burn the same amount of wood more efficiently. So that the same amount of wood puts out more heat, which also has the benefit of putting out less pollutants (something else that has been measured and those FACTS have been shared on this board).


<JP...Perhaps you can point me to these FACTS so that I may become as enlightened as you. Most of what I see I would call opinions. Like what you write.
What did you say that you heat your house with?
BTW, what is your definition of a FACT?>

"Have I missed a site that has some, or has anyone here got a infrared temp gun that they have been using?"

"I thought I asked a simple question, has anyone done any temp readings.
Why are you against a few FACTS to add to your opinions. I am not talking high tech specialized stuff. You can buy a simple infra red temp reader for under $100, some for much less."

There are multiple posts on this board alone about FACTS, including temperature readings... I suggest you read what is available before saying things aren't there...


<JP..I know, you mentioned this FACTS thing before. Again, could you please point me to these facts you tout?>


Electrical codes... hmm, as I said in my previoes posts, codes that are in place for saftey reasons make sense... I also stated at the same time that codes these days do not reflect that anymore. You want to use electrical, okay smart guy, why does the code tell a person they MUST have a certain number of receptacles in a room? Before you jump and say, to keep people from overloading receptacles, keep in mind that most people here or who are interested in these types of things, do everything in their power to reduce their consumption of power. Imagine I went to get an electrical inspection done, and the inspector walked in and I didn't have the required number of receptacle in place, precisely because I only use the grid to charge a battery bank. I would have to tell the inspector that I am just getting it hooked up temporarily. Why? Because the code won't allow you to do otherwise. There are ZERO provisions for doing that... Why??? Because it has NOTHING to do with safety, and everything to do with forcing people to spend extra money, with the electrical company, the suppliers of equipment, and those contractors hired to install them. You seem fond of quoting your past experiences as some mantra... so let me join you on this... I have worked in every area of construction, I have built houses from scratch, I have done all the required work to be a licensed electrician (but choose not to participate in the licensing procedures), I have lived with wood heat for most of my life, I have flipped houses, as in buying houses, doing the work (without hiring contractors to do so), and sold them at a profit.

<JP...It is obvious that you know tons more about safety than the people who write codes.
No mantra, just sharing my own experiences, of which I have had many, wheather you like it, value it, believe it, or not. So sorry that you don't really care to share, unless it is your own opinion.>

Of course what all this personal info has to do with the subject of heating and codes, I'm not sure, but if it makes you feel better to know, there ya go...

<JP...There ya go...what. You did not answer many questions about your heating method. Oh yeah, you did mention that you have heated with wood for most of your life. How long might that be?

You have not answered my critical questions...Living in the great white north where it is sooo cold, how big is your house? How many rooms do you heat? Do you heat every room individually? Do you heat your house with a rocket stove? How big is the firebox, how thick are the walls? How often do you fire it? How warm do you like to be? How much wood do you burn in a winter (or is it really cold in the summer too)?
These are very simple questions. Why not answer them. I hope that they are not too personal. I'm sure others might like to know too.>


As for your comments which seem to indicate a disdain for canada... yes jp that is definately the way to have a conversation regarding stoves and codes, attack another country...

<JP.. Yes, I am certainly "attacking " Canada all right.
You seem very proud to live in NORTHERN Ontario, where it is soooo cold. Not like where I live in Maine where how could I possibly know what cold is. Just havin a little fun, ya know? You sure are a touchy fellow.
A little nasty too I might add. Lighten up, eh!
BTW, I happen to have many fine, and friendly, friends in Canada.>


JP

[jpmanley]

Jeez chronic-tom, whats with all this "attack" crap, and who are these mysterous "certain people" that are attacking people on "general principal"?
If you are going to make accusations, why not be specific, and, by the way, accurate.

I have a passion for anything that has to do with fire enclosed in brick, stone, mud, whatever, with the purpose of heating and cooking.
Am I mistaken, or is this board here for an exchange of info, regardless of if it agrees with your opinions. I stopped by to join in, and maybe contribute.
Luckily, I find your confrontional attitude rather humorous, so I will probably stick around.

I gotta say, judging from the tone, and the way you post, the following 3 paragraphs seem to sound sort of like you. Is that who you are really talking about?

The last paragraph makes you sound like a rather angry person though. Is that accurate?
Did you grow up in Northern Ontario, or move there to get away from it all so you can do your own thing without other people meddling in your reality?

JP








"Well, in some cases, it's because certain people travel around to different sites and attack people on general principal in snide manners, and then try to act like the other person is at fault for doing it.


In other cases, it's simply a matter of people not being able to communicate effectively though text alone. The majority of real communication, is non verbal (or text), as in facial expressions, tone, and body language. Combine that with people's expectation that they know everything, and it ends up with serious conflicts over nothing.

And in yet other cases, it is a matter of people believing that they (generally through their experience), know more then anyone else and when disagreed with, they become defensive. That is the part that was referred to earlier as the 'blinding of oneself'."

And then there are people like me... who have become 100% fed up with people either getting involved in other peoples lives when they don't have any reason to do so (read 'codes' into that) other then a desire to show that they are right, or in people suggesting that their experiences watching, reading or hearing about, is the equivelant for other peoples DIRECT experience. IE, the person who says, oh sure, you SAY it works for you, but what facts do you offer to prove it...

[chronictom]

I see no point to go through and point out specific posts that are freely available to you by a couple of clicks.

There is no distinction between certifying a builder and licensing them, and if you serious ly think that there is, wait a couple more years and see where your program gets us.

As for my personal life, I am sure that everyone here has better things to do then care about it, but seems you so fully beleive that it is important, and that apparently my age has soemthing to do with it, alrighty then...

I'm 37, I own 40 acres of bush, in the middle of the bush, with wood heat as the sole source of heat, in a 1200 square foot home, 3 bedrooms plus pantry and library.

Do I use a rocket stove? No, I am here learning about them, because I will use them.

What is my schedule for fills and such, what in the hell do you think that has to do with squat in what we are talking about? And why do you keep trying to change this from a discussion of the code issue to one about me and my life?

As for me being a little nasty, you have come on here and called every person who has said they use rocket stoves and built them and find them quite adequete for the tasks based on their own personal experience a liar.

You did not say, I can't see how these things are true, you didn't say, in my experience I have never seen the like... you said quite clearly that you don't accept any person's word as fact, and then went on to snidely ask if I did.

Do I? No, but I sure as hell don't tell people that what they say means nothing to me. I listen to them recount their experiences, I evaluate it in conjuction with what I do know is fact, and then I either add it to my base of knowledge or examine it further. For example, if I thought that someone was making claims that were beyond reality in regards to a rocket stove, I would find out what they did to come to their conclusions, and then try to repeat it for myself and discuss the results with them to discover why they did... Or I may jut decide they are a crackpot and walk away, but I sure wouldn't tell them that they are wrong without trying it myself first.

I also wouldn't make snide comments about their country, or their age, whats next for you? Perhaps you wish to comment on my appearance and how that effects wether or not a rocket stove can live up to the 'claims' made on? How about my weight, perhaps I weigh more then you do (or less) and that is effecting the way the heat feels on my body?

Whatever your response is to this JP, the convo is over on my part, this is getting nowhere, you apparently don't wish to discuss the issue of codes and licensing....





"

[Donkey]

Sept 15, 2008 3:02:02 GMT -8 jpmanley said:

I thought I asked a simple question, has anyone done any temp readings.
Why are you against a few FACTS to add to your opinions. I am not talking high tech specialized stuff. You can buy a simple infra red temp reader for under $100, some for much less.

That is the intent of these boards. To encourage the investigation.
It is still deep in our fire season, here in Northern California we have already had one of the most exciting fire seasons in anyone's memory. I do not intent to add to the excitement. When the rains come again, I will once again find the time to pick up my instruments and forge on.. Until then, I will let others perform these measurements..
Perhaps yourself??

But I am still interested.
To say rockets have provided you with comfort, is a vague and individual thing. How large an area do you heat with your rocket?How much do you rely your rocket to heat? How cold and severe is your winter? How large is the firebox? What is the size of the wood you burn? How often do you fire it, and how long does the heat last? How big is the area that you heat? Is it your sole source of heat?

I live in NorCal. The winters here are mild. My home is 1600 square ft. My primary heat source is passive solar. My secondary is my rocket stove and no other (besides waste heat from cooking).
I am running an 8" rocket system and dumping the heat into around (guessing somewhat) 2 1/2 tones of mass, perhaps a little more. My rocket stove is a bit different than most as I can toss in chunks of 18" long by as large as 12" round firewood, mostly oak and madrone. Somewhere between 2 and 4 hours of firing brings roughly half of the mass up to a temperature that is almost too hot to sit on. (sorry, haven't measured with any accuracy beyond that.) The rest of the mass is comfortably warm, hotter than body temp.
After the fire goes out, there is a noticeable heat - one that can be felt from several feet away, radiating from the stove for (up to) 3 days.
Granted, our winters are very mild compared to other places. The passive solar heating I've designed into this house provides around 2/3 of our heating needs, so there is little need for the stove in any case.
Even still, it's the first stove I've built. I made it myself with some crap I found lying around and a little mud, straw and sand. I didn't need an expensive professional or components to make it and it's safe, effective, beautiful and most importantly it provides plenty of comfort.

Perhaps I am thick as a brick, but could you be more specific regarding "language that restricts instead of includes".

Sure. For instance, (maybe a quibble, but) the wall thickness maximum.. What REAL utility does this perform?? I understand your answer from earlier.
But what if a firebox can be devised that heats 12 or 24 inch thick walls without strain, raising the bar on those diminishing returns? When my stove fails to pass inspection because it's walls are TOO thick (not a safety issue) do I then have to go back and fight the codes or change them in order to pass muster?? Will I be forced to rebuild my stove to fit code requirement? What then if my fire configuration CAN heat 24 inches of wall and now blasts away at 10 inches?? Will code compliance have forced me to build an unsafe situation?

Do you suppose that, for instance, electric wireing codes should be written as simple suggestions, but encourage everyone to feel free to experiment?

So as my addendum, I gotta say, if what you wrote about the progress of the folks at Aprovecho, that all they discovered is the pot gap, you have blinders on.
What did you discover, in 2 weeks in a mud puddle cabin, that Aprovecho did not learn in 10 years. I would like to read a few specifics instead of somewhat fuzzy claims of comfort.

You wrote..
<To encourage pushing the boundaries of what it is we think they can do and what it is we think they are for.>

BTW, what do you think rocket stoves can do, and what do you think they are for? No sarcasm here, I really want your opinion on this.

JP

First, to say that they make some of the best wok cookers anywhere. Thank you, Aprovecho!
I have enjoyed a few rocket stove heated showers/baths. Some have worked quite well, some not so. I have personally built both kinds.. I find them to have the potential to be very efficient and with the right tweaks can be made to whip up a few showers in no time with a minimum of fuss and NO SMOKE whatsoever.
I have personally enjoyed part of a southwestern Oregon deep winter on a rocket stove heated cob bench. The building was small and made of cob, with plastic covered window openings. The bench was heated with a smallish six inch stove. Something this experience expressed to me, was the simple concept that it wasn't houses that needed heat but people. We quickly discovered that with butts on bench and feet in something snug, ambient air could be 60 degrees, us in shirtsleeves and STILL maintain a high level of "comfort". SO.. Heat the people, not the space.

Rocket stoves, like their closest cousin (mass heaters), have a built in storage battery. Any material with high mass will do. Brick, metal, sand, cob, water, etc.. Though unlike mass heaters, this battery can be any shape. The floor, a bed, an interior wall, a work surface, a wrap around bench to fit the whole family and so on.

The main distinction of a rocket stove is its internal, insulated chimney. This "heat riser" channel creates a measure of draft, generated internally to the stove. This means that in some cases the "chimney" (external to the stove) can be eliminated altogether and the stove will still run energetically!

In my mind this changes the rules somewhat. Couple this slight rules change towards designing stoves with the efficiencies inherent in the rocket elbow and off we go.

Mostly, the following is some stuff that I've begun to scratch the surface of but yet to have tested thoroughly:

I have been amazed at how high temperature can be produced from some rocket elbows. I have seen a quarter inch steel plate turn cherry red and begin to spark. This indicates (without measuring) something approaching welding temperature in carbon steel.. I wonder if a naturally aspirated forge could be made.

Internal draft.. So, I can take off the chimney and have the stove still run well (which I've seen in a stove with a 20 foot bench). I've experienced exit temps of below body temp (not quite cold) over extended periods of the burn cycle (around two hours), which indicates (again without instrumentation) that a significant portion of the heat produced by the stove stays in the building. I wonder if this effect could be used to create automatically thermo-locking stoves, where dampers are totally unnecessary. I wonder if a "reversed" chimney could be made to create a kind of draft. Could we cool exhaust gasses till they are colder than ambient air, falling to "draft" the stove by siphon? (good way to hide grandpa's still..)

I'm sure I could go on.. But I've kinda gone on a bit as it is.

Ya know, I appreciate any input you got on how to proceed here, testing, safety, rules, you name it. I invite you to come play. It's a fun sandbox and there's plenty of room. I've meant no disrespect of MHA, Aprovecho or yourself. I appreciate how much work you've all done and how far you've brought it..
I would also like to point out that there's still quite a bit to be learned here. The history of our understanding has not yet ended.. So! To carry on..

[jpmanley]

Sept 15, 2008 9:54:48 GMT -8 canyon said:

Jp,
In describing rocket mass heaters to people unfamiliar I call them "poor man's masonry heaters" and I think it is pretty accurate. By creating more positive pressure with the heat riser you can go HORIZONTAL with benches and spread the weight out in a way that one can reinforce the structure affordably. It is a great savings over the major foundation required for a traditional vertical approach. Also, the heater can be made with locally available materials for cheap. I don't know of any that approach the average mass of masonry stoves (20 tons?) as I gather the average rocket mass heaters to have 3 to 6 tons. They can not be expected to provide any more storage than their mass. While I think they can be built for larger spaces with larger mass storage, the "normal" ones are for small spaces. I highly suggest you obtain and read Ianto Evans/ Leslie Jackson's book "Rocket Mass Heaters" as I think it might clear some of the details up for you. Thanks for being part of this forum.

Hey Canyon
Thanks for your thoughts, and having given them in such a civil manner. I appreciate it.
I have a few questions..
Could you elaborate on what "positive pressure" is. Is that another way to describe draft, or something different?
You can go horizontal with benches in any masonry heater, provided the channels are sized correctly, and the chimney flue is sized right, and is tall enough.
What are the cheap local materials that can be used for a rocket, that are not used in a heater?
I am not familiar with any heaters that weigh in at 20 tons. Most of the heaters that I am aware of weigh in at around 3 tons, the same as, or even less than what you wrote that a rocket might weigh.
Could you elaborate on this.." with benches and spread the weight out in a way that one can reinforce the structure affordably. It is a great savings over the major foundation required for a traditional vertical approach."
The footprint for the most common heater, that includes a 22x22 inch bakeoven, that I build is about 56 inches wide, 42 inches deep (60 inches deep with a heated bench). Is that considered a major foundation (as in up thru a basement to support the heater. Does it make a difference if it is all built on a monolithic slab), or is the idea to spread it all out horizontaly to reduce the weight per sq ft so that there is no foundation needed, just a very well built floor?
Hope you don't mind going into these details. I am hoping I don't have to buy a book to figure this all out.

JP

[Donkey]

Ah, what you're needing is a more complete description of the rocket stove as a mass heater.
You are familiar with the Aprovecho, cooking type rocket stove..
Heater rockets have the same heat riser as it's center piece. Though for good draft (for lack of a better word) it should be higher than the classic Aprovecho stove and as well insulated as can be made.
A handy addition to this is an added feed tube, arranged so the works look like the letter j, with a full 180 degree turn. Fuel is placed down into this tube and tends to feed itself in as the underside is burned off. This does away with the Aprovecho style fuel/air plate and horizontal feeds, with the need to continuously push the sticks in as they burn. Vertical feeding, downward, places the fuel in the best position to the air and pyrolysis area, automatically at all times.
After the heat riser can be placed any arrangement of radiator and or mass storage that seems appropriate for the situation. Typically you see a steel drum or barrel placed over the heat riser. It's a quick warm up, take the edge off, heat some air and make tea kinda surface. Exhaust gasses and heat usually flow down to the bottom of this barrel (barrels, 'cause they're free or at least cheap, can handle the heat and are easy to use), is collected in a pipe and run through a mass as storage. This mass could be any shape but is most often something to place your body directly in contact with. How much instant, air warming heat verses mass storage to provide is a balancing act, weigh your needs and design accordingly.
Eventually, exhaust reaches a chimney of some sort and is whisked away in the normal way. Here things can get interesting. It is possible to remove too much heat from the exhaust, making it refuse to climb out of a chimney in certain conditions or create condensation problems.

Those are the basics. I'm glad to answer to the best of my ability any questions.. Remember, I ain't a long time stove pro.. I'm in this for the love of it, 'cause it turns me on. I'm an enthusiast and mainly a home experimentalist.

[canyon]

JP,
Yes, the positive pressure is describing the draft. Draft is usually thought of as negative pressure when in reality there are points of both positive and negative pressure along the flow of a stove. Gravity stack effect is directly proportional to temperature. The hotter the stack temp the faster/more draft. The process of combustion is also one of expansion or positive pressure pushing. When you insulate a vertical "heat riser" where intense combustion of gasses is taking place you get a huge "stack effect" of the high temps rising say 3' at 1500 f(plus internal combustion expansion) that now has the ability to push horizontally(positive pressure) through benches or what have you. These benches can be made of materials available for hauling like rocks, urbanite(reclaimed concrete), clay, sand, straw, used stovepipe etc. all of which can be used for a "regular" masonry stove as well, however, I didn't think it was common but I am only familiar with 7 or eight of these stoves in my area which all used commercial brick. (I do know that in eastern europe local materials are frequently used for masonry stoves as seen/read in Lyle's book).
Yes,in going horizontal with the mass you can distribute the weight so as to get the psf down to a level where a strong floor can support it. This can be (depending on the project) a significant savings over a concrete footer etc. to support a vertical masonry heater.

When I started my construction project that my family and I reside in eight years ago, I had heard of masonry heaters and even seen some but I didn't "know" about them. I learned about them a few years after my foundation was finished (8' basement with 8" solid reinforced concrete walls) and as inspired as I was I could not add it ( I have a major footer/pier right where I would put it but it supports a 14"x14" timber post). So I independently decided I could do a small masonry bench after a wood stove that I would fire all out and charge. Then I got ahold of the rocket mass heaters book and it blew my mind! I am now going to build a much larger 3 ton approx. bench/window seat/ couch lounge area but unfortunately the area where I am building this is currently my wife's office and my daughter's toy area all of which is going to move to where our temporary kitchen is when I finish the real kitchen(I'm getting there but still a little ways off ). Such is the reality of building out of pocket!
I guess my memory was way off on the tonnage of masonry heaters! I called my friend and his is 10 tons (I must of confused 20,000 pounds). But even that sounds like above average from what you are saying. Perhaps with our longer winters the masonry stoves around here average more mass (other ones I know of appear to me to be 7 to 10 tons as a gut guess only judging from the known 10 ton'er). I still think that the rocket mass heaters are typically built with less mass than traditional masonry stoves in general but I obviously could be wrong.
PM me with your address and I'll send you the book.

[jpmanley]

Hey Donkey
Yeah, we have seen the fires in the news, back before the conventions, olympics, and now elections took over. I suppose I wouldn't do much experimenting with fire around those parts now either.
I have done a great deal of experimenting with fire wraped in brick, of all sizes and flue configurations, with the goal of heating, cooking, or both. It is all very facinating, especially for us pyros.
I have rebuilt the heater in my office/shop 3 different times, in totally different ways.
I'm actually looking forward to having fires again. I try to wait till October till I start having small burns.
Luckily I have turned my pyromania into a way of making a living and a life.

How big is your firebox to be able to acomadate the larger volume of wood that you use?
When you are in your coldest of winter fireing, how often do you have a burn? Once a day, every other day, etc?

About wall thickness...
You're right, if someone wanted to enlarge the firebox and make the mass a foot or two thick, I suppose a code enforcement officer could give you a hard time.
But we can't necessarily assume that would happen either. The odds are in your favor if you know way more about what you are doing than he/she does. If you know your stuff, slack is often given. They want to know you know what you are doing is safe, and that you can show them. It helps if you can present documentation that you do indeed know what you are doing, like something showing the test fireboxes that you have been experimenting with already so that you can assure him/her your special firebox will perform as promised. Photos, lots of them.

I have been there and done that for the last almost 40 years. I have never had a problem with a code officer (knock on brick). Some of it is how you present yourself, part of it is how you treat the code person, as in attitude.


I do have to add that unless your added mass was for mostly looks, there are a few other ways to add mass to a heater without reducing the surface temps or enlarging the firebox.
Unless, that is, you were trying to heat a 47 room house.

You stated that "unlike mass heaters (I assume you mean masonry heaters ) this battery can be any shape.
I have built added mass to masonry heaters that you can walk on, sleep on, lean against and have the whole family sit around. As well as cook and bake food. It is done, and has been done for hundreds of years. You have seen the ones in Europe havn't you.

I have a very different take on draft. For our conversation I am assuming that we have our heater/rocket installed on the living floor of the house,( as opposed to in the basement), sufficient make up air and properly sized chimney flue..
As see it these are the main components to having a great draft exist before the fire is lit, in order of importance.

Colder outside than in, so the air rises of itself, creating draft. If it is colder inside, the air in the chimney is cold and tends to want to sink instead of rise, usually causing the smoke to spill into the room.

The taller the chimney the greater the available draft.

Chimney located in the middle of the house so that it stays warmer.

A stiff breeze with a clean shot over the chimney top can increase draft considerably.

If you have the preceding conditions, your draft could suck the lipstick off a moose (we have em in Maine too), before the fire is even started.

So I have a hard time with the design of the "heat riser". If you replaced it with any tube or flue tile, just to get the smoke to the top (if you don't buy the bell theory and forget the tube), the smoke should still cruise along just fine thru whatever convolutions you like, assuming above said conditions.

When you fired the rocket with the 20 ft bench, without the chimney, did you start the fire without the chimney and it got going, fired up and worked well, or did you start the fire, get it going, then remove the chimney? When the chimney was removed, was the end of the flue from the 20 ft bench sticking out horizontaly or did it go up vertically to where the chimney was removed.

If any other members of this group were members of the MHA, we could make a seminar out of it at the annual meeting, We build all sorts of heaters and ovens, fire them up and do temp and emissions testing, and of course, pizza.

Thanks for the welcome!

JP

[Donkey]

The 20 foot bench I mentioned... Started the stove without a chimney. The bench runs horizontally at about firebox height, perhaps a bit below and the exhaust exits straight out the wall at a few inches above floor height..

So I have a hard time with the design of the "heat riser". If you replaced it with any tube or flue tile, just to get the smoke to the top (if you don't buy the bell theory and forget the tube), the smoke should still cruise along just fine thru whatever convolutions you like, assuming above said conditions.

Yeah.. That's kinda my point. It appears to work to a degree without those pre-existing conditions you spoke of. Sort of changes the rules a tiny bit. In fact I've experienced the "colder inside, stove wants to smoke" condition, to solve I went around to the back and pulled the chimney off. The stove then lit and ran. I could then put the chimney back on once things were warmed slightly..

The heat riser IS A CHIMNEY.. Inside the stove itself..
As you well know, the hotter the inside of the chimney (relative to the outside) the more draw it can produce. A heat riser, being well insulated can get extremely hot, producing a measure of draft WITHOUT an external chimney at all.
Consider it an internal, 1500 degree 2 1/2 foot high chimney..

[Donkey]

Honestly, the problem with the 20' stove was poor placement of the chimney. It was round back, outside, on the north-north west side, down in the shade and far too short. It had hard to light as a permanent feature.

I was surprised to discover that taking the chimney off would improve things.

The long term solution for them was to chop out the cob below the chimney from the inside and install a primer box. A primer is a small chamber just below the chimney, toss in a sheet of burning phone book and close the door to get the chimney started on difficult days. Of course, since the box was an afterthought, it's now on the other side of the room in an thoroughly inconvenient place.

[jpmanley]

You are correct, a poorly built or placed chimney can indeed be worse than no chimney at all, and can actually surpress draft.

I have built a number of small experimental masonry heaters, as well as some small experimental cookstoves and rocket stoves (such as the helps stove) outside in my dooryard, without a chimney, and without an internal heat riser, and they will burn, but not as good and hot as they will with a proper chimney and increased draft. At least in my experience.
I agree that there is internal pressure from any fire, as in the expansion of gasses, and that will assist in pushing the smoke out most any flue, or open firebox door. It is also true that as the flue system gets further from the fire, you can taper down the size because the gasses contract as they cool.

When starting a fire in a cold heater, and the chimney is cold and the conditions are not so good for a natural draft, it is often suggested that you put a ball of newspaper into one of the clean out ports at the bottom or end of the flue channels and light it. As you mentioned. That works sometimes, but if the conditions really suck, it doesn't.

I have found that the method of loading (stacking) and lighting the wood is almost more critical than the myriad of numerous flame path designs (assuming proper mass and flue channel sizeing).

The best way to actually create the best ignition conditions is by building your fire top down style. The fire starts with kindling at the top of the pile, and thru the process of "reverse pyrolysis" the fire works its way down thru the cradled pieces of fire wood, pieces that gradually get bigger to the bottom of the pile. For instance, I start with 5 to 6 inch diameter firewood on the bottom layer, working down to1 inch firewood with dry kindling on the top. If you build a traditional fire, usually the exact opposite configuration, the burn is generally very smoky for a while as it gets up to operating temp. It is a very dirty phase when built in that fashion, but it is how most people start fires.
The top down burns very clean, as the wood below outgasses into a healthy fire above it, allowing complete combustion. If you view your chimney top during ignition, you will see a very distinct difference in the amount of smoke from the different methods. The top down burn produces very little smoke all the way thru to, normal operating temps of 1200F to 1500F.
I have stood outside and watched my heater fire (glass doors), and the chimney top from the same vantage point. From a very small fire, to the entire load of wood engaged, there is barely a whisper of smoke from the chimney top. Steam yes, but little unburned gasses (smoke).

In a top down burn, starting as a small fire with the dry kindling on the top of the wood load, it is the same as putting newspaper in the base of the heater or chimney clean out to jump start the draft.

Of course, if you are operating your heater or rocket on a daily basis, your heater and chimney flues are never cold when you start each burn, IE good draft already exists. I start all my heater fires in this fashion, as well as to fire up my bakeovens or even a camp fire. I have not even used any paper to start my burns in 10 years, just scrap lumber I scrounge from job sites, or dry pine cones that I collect in my woods.
Of course, dry wood is essential for good top down burn ignition.

I mention the top down burn to you because you mentioned the larger wood that you burn, so your firebox might be large enough to actually build a top down firewood stack in the firebox, if you wanted to try it out.

Do you have a infra red temp gun? I am curious as to what temps the outside of your bench reaches (when you start having burns again).

Ok, I have rambled on enough for now.
JP

[Donkey]

I know of top down fires.. Thanks for the reminder and recommendation.
I don't have a temp gun. At some point I'll need to get one.. Perhaps after the next paycheck (or so). Are there any brands that you would recommend?

The down-feeder tube of a rocket stove (by the way) encourages reverse pyrolysis. The fire always eats it's way backwards in to the fuel.

[ernie]

Ok folks I know what these guys have gone through and it has not been easy nor cheap.
its hard to wrap your head round how a rocket does its job when the pardime you have been working in is that you have to heat all the inside space to some arbitrary temp.

just a few things to think about in responce to the posts here.

1. a rocket stove is not a masonery stove. it shares some similarities but it is not the came critter.

2. rocket stoves are not dependant on draft. a rocket stove is a pusher your only draft section is the heat riser and it is enclosed every thing beyond the riser is pushed up and out of your system.

3. our exhaust gas temps at the end of the system are way lower than a masonery stove requires. this is a boon and a problem in that the stove must be configured properly to push cold wet exhaust up a chiminy.

4. the thermal mass we heat is diffrent than brick. and the masses we use are not the norm.

5. you can get the amount of thermal mass you need to heat the house by heating a wall or bench and in this you figure out the cubic feet needed to heat for x numbers of hours.

our house bench is 3 feet wide by 16 feet long by 18 inches deep. it provides heat for 18 hours after fireing (this is when i need a sweater so about 60 degrees) if i fire the stove for 2 houres every 12 hours the constant temp is about 70 degrees in the house.

I live in a Cross shaped house so the low temp end of the house is the long leg of the cross. this room will stay at 65 or so for 12 hours. I belive the big diffrence is in how much heat a rocket stove harvests and stores. for us 10 inches or more is relitivly nominal because we are filling it with as much heat as we can squeeze out of the exhaust. for a masoney heater this is verging on to much mass for the flow and heat uptake.

some thing to think about is that a masoney heater needs a chiminy to operate this requires a certon amount of heat to work. we need a vent and if it is down hill from our stove so much the better cause the fog will roll on out or the steam will condence and flow down hill.