Building the Ultimate Rocket Mass Heater FAQ

The people who really know about Rocket Mass Heaters believe they can solve a huge number of global problems.  The problem is - not enough people know them well enough to speak with authority, and there a heaps of misconceptions.  We aim to change that - but how?  

The goal is to develop a giant FAQ for Rocket Mass Heaters.  In so doing, we aim to dispel these misconceptions, paint a picture of all that Rocket Mass Heaters offer to individuals and the world, and give away this invaluable knowledge.

We have a good start here: https://richsoil.com/wood-heat.jsp#faq.  Are there questions you would add?  If so, post them below, s'il vous plaît.

An anecdote to provide some framework, and food-for-thought:

My Marketing Experience with Red Bull Energy Drink, as an analogy to the challenges and possible solutions we face with Rocket Mass Heaters.

In a former season of life, I worked for the energy drink Red Bull.  I was one of those college kids that drove around town in a mini cooper with a giant can on top.  (Don't judge.  It paid well for a flexible college gig and let me quit my job at Wal-Mart.  Also note, most of these methods are similar to, or even identical to commonly employed evangelistic tactics.  Don't go cider-press on me with this point, just food for thought.  Evangelism, by definition, is "the spreading of good news by public declaration or personal witness," and I contend that this is applicable for Rocket Mass Heaters - way more so than energy drinks, at least.)  

What was interesting about the Red Bull gig (it wasn't the drink - I never drank it) was the methodology and the training we went through to effectively communicate about the product.  Once a week, the whole guerilla marketing team (we were called the "wing squad") gathered and did role-playing exercises so we could practice communicating an internalized script, regardless of the context or the person we were talking to.

The goals of these interactions were simple:

1) Dispel Myths and Common Misconceptions about the product.  
2) Highlight the Virtues of the product, particularly those that are most relevant to the given situation
3) Provide an Experience with the product, as a gift.



1) Dispel Myths and Common Misconceptions
For Red Bull, there was one primary myth.  Namely, that it was an alcoholic beverage, due to its prevalence in the bar scene.  
Therefore, near the beginning of each conversation, we would ask if people had heard of Red Bull, and if so, what they thought of it.  Many would say "isn't that beer?"  Tee-up for, "well, actually, no.  It's an energy drink."

For Rocket Mass Heaters, there are many myths and misconceptions.  
So we could perhaps start like we did with Red Bull.  "Have you heard of Rocket Mass Heaters?"  And, if so, "What is your impression?"  That will likely tell us what we need to know to dispel any misconceptions.

It has to do with rockets.

    Actually no, the name "rocket" is derived from the whooshing sound of the incredible draft.

They aren't reliable.

    Actually, due to the ease of construction of the J-Tube style RMH and the incredibly clean burn, they are among the easiest-to-operate, safest, and most reliable wood-burning stoves in existence.

They're hard to build.

    You can build them in a couple days with a small crew, or hire an experienced builder - maybe for less than the cost of conventional heating installation

You can't build one in a city.

   Not only are codes coming around, but there are also now multiple UL-certified Rocket Stoves on the market that can be purchased and delivered, ready-to-install.

You can't build one in a rental.

    The Liberator and the Pebble Style RMH are just two examples of RMH systems that are easy to install AND uninstall, should the need ever arise.

You can't build one in a conventional home.

    There are RMH systems suitable for any and all weight limitations and building systems.

Aesthetic misconceptions (i.e. cob, barrel, footprint)

    RMH don't have to use barrels, or cob.  Some of them are simply beautiful, and some of them are hardly noticeable in the room at all.

The list goes on.



2) Highlight the Virtues of the product, particularly those that are most relevant to the given situation
For Red Bull, we had an easily memorizable bullet list.  It has been 20 years, and I still remember them!  If I could take that brain-space back, I would.  But it goes to show you how rehearsing these things works, from a psychological perspective.

About the same amount of caffeine as a cup of coffee

Less sugar than a cup of cheerios

Supplies Taurine, a non-essential amino acid that the body can't produce (forget that it's not actually an amino acid, but an organic compound) responsible for muscle recovery and the elimination of lactic acid

For Rocket Mass Heaters, the virtues are incredibly well-documented and compelling.

Carbon neutral or negative

   Far smaller carbon footprint than electric, natural gas, or other wood stoves.  When used in conjunction with proper woodlot management, can represent a truly carbon-negative home-heat solution.

Cheaper to operate than any other form of conventional home heat

   Some people use just 10% the amount of wood that they used to use with their "high efficiency" wood stoves.  Some people heat their home with sticks that fall out of their trees.  Some people heat their homes with junk mail and amazon boxes.

Cleaner burning and safer than any other wood stove

Cheaper to install than other home heat systems

et cetera


3) Provide an Experience with the product, as a gift.
For Red Bull, we'd give the person a can at the end of our interaction.  Interestingly, we were very intentional to never use the word "free," but rather "gift," in order to communicate the value of the item given.  We would give them a chance to respond, and then ask them for a lead, or a reference to someone they know personally who could use the same gift.  They would call their friend and tell them they were sending the wing squad to them with a gift.  Instant raport and credibility with audience #2!

For Rocket Mass Heaters, this experiential component is more difficult to attain, but perhaps more crucial for conversion.
We need to get folks' bodies onto the mass in the dead of winter to truly communicate the experience.
We need physical representations of various fuels that provide winter heat:

a massive pile of coal representing electric and, well, coal

I don't know, uranium and a tumor or something, representing nuclear

a massive pile of plastic and gasoline jugs representing even "renewable" electric like solar and wind

a massive stack of firewood for a conventional wood stove

a teeny-tiny, neatly stacked half-cord of kindling, and/or a pallet of waste paper, representing the fuel required to operate a RMH for 1 cold winter

Perhaps we should aim to document the installation and usage of a dozen or a hundred in every major cold and temperate-climate municipality in the world so people can start to experience them first-hand.



With this in mind,

Considering the Myths and Misconceptions facing Rocket Mass Heaters,
Bearing in mind their Virtues in our modern context
And the desire to provide people the gift of a RMH Experience

What do you feel should populate this Ultimate Rocket Mass Heater FAQ?

What a great idea that could be used elsewhere if practised, thanks.

Hi,  A couple of thoughts.    Would you, could you devise that red bull "system" into the RMH ? Then do skype with a bunch of people to evangelize?  

And the desire to provide people the gift of a RMH Experience

  I used to have tupperware parties and others to sell things.  Why not have RMH parties, and give a free booklet as a gift to people after they experience an RMH in person?.

What are their footprint dimensions? How small can they be?

What sized diameter/length fuel can it take?

If I had one in a cold cabin during winter, and I show up late at night to start it, will it warm me up quickly, or take a while to radiate heat?  

About how often do I have to add fuel to keep it going in winter?  

Can I purchase all the necessary materials to build it from a big box store?  

How much do all the materials cost, retail?

Are there any professional companies dedicated to construction of full RMHs?  Where is the nearest one? How long (man-hours) does it take a professional to build?  How much does it cost to have one installed by professionals?  

How heavy is an RMH?  

Can all the materials to build one fit in a car?  Would it take multiple trips, or just one trip to carry to the install site?  What about an SUV/truck?  

Where is the nearest RMH in my country/state so I can see/try one out in person?

Does it work with existing flues/chimneys/stove exhaust systems?

Are there portable RMHs in case I need to move?

Do I have to have that big metal barrel?  

Will that big metal barrel ever deteriorate?  Will my RMH last longer than a regular metal stove?

How about constructing RMH's in strategic locations so that those that are truly interested in them can go to the location, examine the installation and perhaps even experience it's effectiveness of heating the structure while the weather outside is frightening.
Ideally set up some regional RMH construction sites so that those that are motivated can observe the construction and maybe even participate in helping to building one (Homes for Humanity came to my mind, may be a foothold for a RMH project). This could be a WIN-WIN project;  RMH info-mercial and lowering the cost of heating for those that are going to get the homes.
The other area to consider and get with the sponsors are those that are building "tiny homes" for homeless veterans. Very efficient use of an RMH to provide warmth to every corner of the home.
Just a small "brain" burst.

Hi All, I really liked Mark's ideas.  The tiny home industry is really starting to take off and the ones being built for homeless veterans would be a great idea.  Since these are mobile and going all around the country as their destinations it might also serve the idea to get them spread around more broadly.  Great thinking Mark.  Keep the brain bursts coming.  Brian

I will throw in my two cents.  I think that Rocket Mass Heaters are a fantastic idea.  I believe in them and that is ironically part of the problem.  At the moment the "Gospel" of the RMH has been thoroughly spread to the Permies community but has had little penetration to a general audience.  Paul essentially mentioned this recently.  I like the "Red Bull" idea, but how do we translate going from a mini-cooper to a RMH?  Is is possible to build a portable RMH for demonstration?  Could we bring one to cold events to show it off (tailgate parties?)?  Maybe drag one to a construction site for the dual purposes of workers warming their hands and showing actual tradesmen that the device can be built and get contractors to get used to the idea--to help make it more a normal occurrence in a home?  I am sure that these ideas have been thought of before so please forgive me if I am retreading old thoughts.

I do think the idea of evangelizing the merits of the RMH is a highly worthy effort.  From a little bit of history, the only times that energy consumption has really changed has been when energy became prohibitively expensive and a new option became available.  Electricity was far cheaper than Kerosene which itself was far cheaper that whale oil (as an example).  At the moment, there could be a real heating emergency this winter in many parts of the world and the time for evangelizing the merits of the RMH is better than ever.

Now is really the time to act.  This is a great thread for brainstorming ideas.  Great job Beau for starting this thread!!

Eric

I'm afraid the RMHs for tiny houses/shelters for homeless people wouldn't work - those are generally too small to fit even the smallest RMH, and the population tends to have issues that might make fire operation unsafe or difficult. Also, they tend to be built in urban areas where firewood supply is iffy. Of course, if some of them could build an RMH in one of the self-organized and unregulated settlements (which tend to be in wooded areas), that could be valuable. Unfortunately such things would probably not be conducive to spreading the word widely as they are reclusive by nature.

On the other hand, if RMHs could be incorporated into Habitat for Humanity homes, that would be a massive boost for publicity and acceptance. They are modest homes but would fit an RMH fine, and they generally have a back yard where wood could be kept. Working with the national or regional HFH organizations could develop a path to standardization, and it may be that authorities would look favorably on a proposal by HFH where they would laugh at an individual.

Glenn Herbert wrote: On the other hand, if RMHs could be incorporated into Habitat for Humanity homes, that would be a massive boost for publicity and acceptance. They are modest homes but would fit an RMH fine, and they generally have a back yard where wood could be kept. Working with the national or regional HFH organizations could develop a path to standardization, and it may be that authorities would look favorably on a proposal by HFH where they would laugh at an individual.

Building these into the HFH homes is a very cleaver idea.  I am 100% behind that as a way of promoting the RMH.

For the last few days, I have been reading about RMH and Rocket Stoves.

In one thread it discussed using water as the Mass which I thought was brilliant.  Having an RMH and water storage all in one.

I am starting a list of reading material so I thought I would share these:

https://permies.com/t/186176/Rocket-Scientist

https://permies.com/t/187667/Studio-Dragon-Batchbox-Rebuild

And here is a way to earn PEP BB while making your own RMH or Rocket Stove:

https://permies.com/f/403/pep-rocket

Love this thread,   Thanks for another great one Beau.

You asked for additions to FAQ, sorry, that’s not what I have got.

One of the difficulties of introducing new ideas is the willingness of a population to hear about the new thing.  It goes better if they are feeling a need for the thing being presented.  In the USA, satisfaction with with the existing options is adequate to keep us entrenched.  RMHs seem sketchy, proponents seem sketchy, fringe, maybe even “undesirable”.  

Not my opinion, but I do pass among people who hold these basic deep prejudices, I’m just reporting my observations, disturbing though they are.

The dire situation in Europe as winter approaches  has created an audience that might be far more receptive to RMH know how.

Not heating with gas or electric is how it is going to be, for many many people.

A peace corps type operation there, introducing and teaching RMH technology would most likely save suffering, human lives and forests!  A group of people ready to live in difficult conditions, while they work.

I would volunteer for a couple weeks, paying my own fare, but I am just one old woman with limited experience.  There need to be more people with greater experience, greater knowledge and greater organizational skills ….. People to find or recognize the resources…. eg all bentonite cat litter for clay…

Think of the relief activities after a great disaster (tsunami, tornado, hurricane, wake of military action where infrastructure has been destroyed, and atrocities committed), that’s what I am thinking of, only in advance of the disaster.

If there’s a way to put an effort like this together, and it is successful, then RMH acceptance will not be far off.  IMHO.

Instead of trying to appeal to everyone with a RMH, I suggest targeting the prospects. Who is the ideal candidate for a RMH? What skills and physical capacities are needed to build and maintain an RMH?  What kind of home is most adaptable to a RMH? Exclusivity can be an effective marketing strategy.
Recently, I went to an 100 year old adobe home where the original fireplace was modified to accommodate an RMH. The elderly owners had no idea how to maintain the system and the builder is long gone. The off-gases and ash inside the home are a real health hazard for these people.
I have to admit, this experience put up many cautionary flags and put the breaks on my RMH building project. I am uncertain that I have the necessary skills and don’t want to devalue my home. Yes, there are many links on permies but a simple inclusion/exclusion document would help.
Focusing the RMH marketing strategies on the most successful adopter profile may be more appropriate than trying to convert everyone. "RMH: do you have what it takes to heat for free?"

Or, being as there is plenty of RMH expertise in Europe, how can we help you?

Awesome thread!!

How small can an effective RMH be? Pushing the limits.

I've heard complaints at wheaton labs and I've read comments on permies.com that discourage small systems (6 inch or smaller) and many experts encourage 8 inch or batch systems.

What are the limitations of a small system? Can we work around them?

Can I make a system from stuff I can buy at a hardware store? Out here, un the country, I know I can find things like straw, or wool or barrels. A little resourcefulness is easy for me. But can my sister, who lives in a metropolitan area find the right stuff?

If I made a very small system, with a pebble bench, what pipes can I use to vent it? Metal plumbing pipes? Old trampoline frames?

If I built a j tube out of mineral board (or ceramic board? What are the names for it?) Like a matt-walker style core, how much insulation does it need? What insulating materials can I use? (Besides cob?) Cement? Mortar? Stucco? A mixture? Maybe something a pet store will have?

We are rebuilding our 200 square foot old cabin to live in.  Southern Missouri Ozarks.  We both work so not a lot of time and energy. We have decided to go with a us stove 300 dollar wood stove.
We still have an RV about 30 foot long that could benefit from possibly a rocket mass heater.  But I don't know enough about it.

Beau Davidson wrote:

a teeny-tiny, neatly stacked half-cord of kindling, and/or a pallet of waste paper, representing the fuel required to operate a RMH for 1 cold winter

So maybe we need a separate thread for any of our RMH owners/users willing to volunteer a bit of time. Each user, will take a picture of their stack of firewood pre-heating season. Then they would take a picture of the same stack when the season is over. They would include some weather data - average degree days, how the winter compared to typical winters etc. and maybe some info about what temperature their house was usually kept at.

Then we'd have some before/after images of real-life rockets in action. I know I'm on the spectrum of "visual learner", but am I the only one who would like to actually see some real-life before and after pictures?

and wrote:

Provide an Experience with the product, as a gift.

Would it be worth making a series of pamphlets aimed at different housing situations? Yes, an RMH won't fit in a supper tiny house - but many of those houses are being built in a community, so pictures of the bum warmer and measurements to build an outdoor installation might work.
For renters - pictures of pebble style ones
I realize a pamphlet isn't much of an experience, but it would still be a bit of a gift and it could include web addresses and names of books etc.

Quote is from https://permies.com/p/1581619

T Blankinship wrote:
Is there a video of one person building a rocket mass heater by themselves?

How would you explain to your insurance what a rocket mass heater does and how would they treat it?

I think if you have five to ten builds in a city in a year, this would be a big help in getting the word out.

Also what about a QR code for a rocket mass heater? A short video explaining how a rmh works.

A good subject for the FAQ would be a part for insurance companies and code enforcement/local government questions.

This is great! While reading this my thoughts went back to our current systems in place.

Mass Heaters (MHs) need an industry (an official group of people/companies who are committed to helping further MHs.) This could be a temporary group that would for a more permanent group.

This industry could create a few work groups:
1. One work group to create code regulation standards to be submitted to the NFPA (National Fire Protection Association).
2. Another work group could create training materials for helping entry-level and heating professionals understand how to install and maintain MHs
3. Plus we cannot forget a work group to create a network of Mass Heater Professionals (MHP), which would include individuals and companies. This network would be the ones you would want to help sell or evangelize MHs.

I remember at school there were these large boxes full of concrete. They were heated while the electricity was cheap then held the heat until it was go home time. The RMH is a similar system.
I think a modular system would work very well to replace oil and gas heaters. It is not that hard to collect the required wood over the year.  A lot of city parks have trees that drop branches.

I think one of the myths that needs to be dispelled  has less to do with the RMH and more with the romantic notion that it is somehow it is advantageous to cram a metal box full of wood, choke down the air supply, and let it smolder all night while it makes poisonous gases and creosote.  Hot, clean burn and slow steady heat discharge needs to be better understood by the uninitiated.

Thomas Tipton wrote:I think one of the myths that needs to be dispelled  has less to do with the RMH and more with the romantic notion that it is somehow it is advantageous to cram a metal box full of wood, choke down the air supply, and let it smolder all night while it makes poisonous gases and creosote.  Hot, clean burn and slow steady heat discharge needs to be better understood by the uninitiated.

Yes, it does need to be dispelled.  I know people who do this, and their logic is that it will burn longer, as you say, overnight.

They are good people doing what makes sense, to them,  and what their friends understand.

Ignorance enters the picture, but it’s no sin to be ignorant!  Not everyone has the same kind of brain/OS.  They’re doing as they’ve learned, and in later years of their lives, they don’t have a clue that they were taught “wrong”.

We need to dispel a mindset gently and carefully and supportively, because it’s a widespread and harmful mindset.  We want to keep in mind how offensive is the “department of make you sad” and take care not to be just like them to the people who smolder their stoves all night.

I am going to post a link below about group learning, “what you know and who you know it with” seems to be part of the message.  It seems germane to the situation, and possibly provides an understanding that can be a powerful tool.

https://soilcarboncoalition.org/pipelines-versus-platforms-power-and-the-politics-of-knowledge/

and

https://soilcarboncoalition.org/why-learning-networks/

Very thoughtful blog posts!  Not about RMHs, but about gaining acceptance of new ideas.  His topic has been soil carbon, another important concept that needs wider acceptance, what the blogger has done, and what he has learned about people and learning, which I think, is what we’re talking about here.

I will be happy if just one person has an ah ha moment from them, but of course am hoping for a lot more😊

Paul Fookes wrote:

Glenn Herbert wrote: On the other hand, if RMHs could be incorporated into Habitat for Humanity homes, that would be a massive boost for publicity and acceptance. They are modest homes but would fit an RMH fine, and they generally have a back yard where wood could be kept. Working with the national or regional HFH organizations could develop a path to standardization, and it may be that authorities would look favorably on a proposal by HFH where they would laugh at an individual.

Building these into the HFH homes is a very cleaver idea.  I am 100% behind that as a way of promoting the RMH.

How easy would it be to do a kickstarter to put some RMH into HFH buildings?  What would be the cost?
Information on: HFH USA: https://www.habitat.org/where-we-build/united-states-america
Information on HFH Asia Pacific: https://www.habitat.org/ap

We just had a new user from Germany who posted HERE:

https://permies.com/t/160/191709/people-rocket-mass-heaters

Basically, she wants to install a RMH, believes in the RMH, but needs regulatory approval from someone who will probably grant it but he needs to hear the information in German.  Basically, new user Christine is asking for just one, concise video to have German subtitles added, preferably the type that a human adds as the automated ones will almost certainly miss or err on important details.

Are there any German speakers and does anyone know anything about adding subtitles to a YouTube video?  Right now is the time as Germany is probably in for a very cold winter this year.

Eric

Regarding German subtitles, I am not sure, but what video is being requested?  

That is the question.  There was no specific mention, just a request for a concise how-to-do video.  The OP mentioned that there are copious videos in English but none in German.  So I am thinking a 20 minute or so video demonstrating the construction process and maybe something explaining why it should pass codes.  I am sure we have a bevy of such videos.

The Habitat for Humanity idea is a compelling one.

I keep thinking, surely someone has gone down this path before.  I know there are some Habitat folks popping into the forums now and again.  Maybe they will see this and chime in with opinions/guidance.

I had a look around Habitat.org.  The information about their innovation center is particularly of interest.  

Housing products and services "address both the supply and demand sides of the market when we advise firms who are considering introducing housing products or services."  Might be a great place to start, too.  Anyone wanna take this on?  Their email address is TCIS@habitat.org.



Or we should start by contacting some local Habitat offices, like Habitat for Humanity of Missoula, or ones near our homes.

Yes!  Contacting Habitat is a great idea.  Perfect way to spread the message.

Eric Hanson wrote:

Are there any German speakers and does anyone know anything about adding subtitles to a YouTube video?  Right now is the time as Germany is probably in for a very cold winter this year.

3 step program:
1. Identifying the best video to use - we maybe need a couple of our rocket scientists to choose that.
2. Adding subtitles: I know that Raven has worked on that for some of her videos - she asked for proof-reading help, but she'd somehow downloaded the automated closed caption from Youtube to a program like we've used for editing in (maybe some sort of google sharing thing???)
3. Translating those subtitles into German: I know we've got a couple of staff and several members that live in Germany. I don't know who or how many would feel competent to officially "translate", but even having them get the ball rolling would be a help.
If we can even get to that stage, if we haven't found a translator, we could ask via the dailyish.

The request seems worthy of at least looking into. There have been discussions I've read that just calling it a "Masonry Heater" and not using the proper term Rocket Mass Heater seems to calm a lot of the Northern European inspectors, as the Masonry Heaters have been around for many generations - yes, not really the same beast, but a close cousin - heat a big mass, fire goes out, mass keeps heating the room!

Going from a MINI-COOPER to the RMH uses the same Segway that motivates 90% of us, $$$ and comfort.
There are breakdown RMH's so one of these could be taken to a cold weather construction site to illustrate their versatility and the comfort that they give in heating an area with a teeny tiny carbon foot print. The Red Bull agenda when presented to a group of partially motivated individuals would be a very good event to consider. Need a testimonial with heating bills that backs-up the claims made. Making this available to charitable organizations will bring rewards to everyone that participates. Give of yourself and you will receive back 10 fold what you have given.

This is an awesome thread, thanks Beau!

People have already covered all the questions I can think of.

Beau Davidson wrote:The Habitat for Humanity idea is a compelling one.

I keep thinking, surely someone has gone down this path before.  I know there are some Habitat folks popping into the forums now and again.  Maybe they will see this and chime in with opinions/guidance.

I had a look around Habitat.org.  The information about their innovation center is particularly of interest.  

Housing products and services "address both the supply and demand sides of the market when we advise firms who are considering introducing housing products or services."  Might be a great place to start, too.  Anyone wanna take this on?  Their email address is TCIS@habitat.org.
Or we should start by contacting some local Habitat offices, like Habitat for Humanity of Missoula, or ones near our homes.

My way forward would be to find a project near to where one of the RMH experts live and can supervise others doing the work.  Missoula sounds ideal to start and then spread to word.  The other area may be PNW where it gets seriously cold.

In Europe and Ireland in my case, nobody really know about this, I came across to it because my interest for permaculture.
I've started to learn how to build one, read a book and now working on a design but this is not simple when it's the first time you do this.
It would be good to have access to experts (for the design) from different part of the world willing to help for free or a fair price, the forum here is great but you still have to do a lot of researches before asking pertinent questions. Also finding the correct material is not easy when you're not doing DIY for 20 years.

Like I've found out about the 4'' exit chimney I had in place for my wood stove and I am quite sure it is too small (in this thread, they were saying 6'' is already too small, we should use 8'') and I can't use bigger in my design because the cross-sectional area ...  or can I?

I'm already promoting the idea but I need to do it first then people will see how good it is!

Julien Vailles wrote:
Like I've found out about the 4'' exit chimney I had in place for my wood stove and I am quite sure it is too small (in this thread, they were saying 6'' is already too small, we should use 8'') and I can't use bigger in my design because the cross-sectional area ...  or can I?

I think that person was exaggerating or over generalizing. At last fall's rocket mass heater jamboree, Paul and uncle mud concluded from various experiments over the years that 4" RMHs don't end up working efficiently. There are numerous examples of 6" systems that work very well. They are now considered the smallest worth building though. Your 4" exhaust would restrict a 6" system and prevent it from performing well.

I am in Devon, England. Living in a truck. Kitchen outside. I may b able to build a cabin in a few years. The whole RMH thing frustrates me as I would not b able to build myself and very few people seem to know anything about them.
I think training up ‘an army’ of people with the knowledge is the key; that way the the certification standards will come.
I would love to buy a RMH ‘off the shelf’.
Hoping I will b able to do this in the next 5 years 🤞🏼
It makes so much sense. I am 67 and can’t be felling and chopping enough fuel for a standard wood burner for many more years.

Coydon Wallham wrote:

Julien Vailles wrote:
Like I've found out about the 4'' exit chimney I had in place for my wood stove and I am quite sure it is too small (in this thread, they were saying 6'' is already too small, we should use 8'') and I can't use bigger in my design because the cross-sectional area ...  or can I?

I think that person was exaggerating or over generalizing. At last fall's rocket mass heater jamboree, Paul and uncle mud concluded from various experiments over the years that 4" RMHs don't end up working efficiently. There are numerous examples of 6" systems that work very well. They are now considered the smallest worth building though. Your 4" exhaust would restrict a 6" system and prevent it from performing well.

Thanks a mill Coydon! It confirms my thinking, I'll see if I can replace it with a 8'' (reason being is I've got a ~100sqm 2 floors stone house so I need some output), if not I'll switch for a 7'' (I don't know if it is available) or 6'' ..
I'm planning to create a new thread to get my design validated by the community!

Cheers,
Julien

Julien Vailles wrote:Thanks a mill Coydon! It confirms my thinking, I'll see if I can replace it with a 8'' (reason being is I've got a ~100sqm 2 floors stone house so I need some output), if not I'll switch for a 7'' (I don't know if it is available) or 6'' ..
I'm planning to create a new thread to get my design validated by the community!

Which brings up another main point to cover in a FAQ: what size pipes are readily available/used?

In the US I've only seen 6" and 8" discussed. When we set up the Gamera (sp?) RMH though, it was from a European country and used something totalitarian (metric)- I think it ended up being close enough to 5" that some of that was found to work...

Two questions that might go in the FAQ (if anyone has answers, that is) are: are there any dimensional ratios that the builder should stick close to for best efficiency? And, how big should it be for a given area and type of thermal mass used?

Beau, I really think you’re onto something here, and your Red Bull experience transfers quite well to what you’re trying to accomplish!

Here’s another not so frequently asked category of questions.  

In the absence of stovepipe, how do hand built firebrick square flues cross section areas compare with cross section area recommendations based on round metal pipes, and is it possible to build a flue out of fire brick, or fire cob, if so, are there accommodations needed for the friction in a cob flue not present in smooth metal pipes.