My rocket, adapted to a warm place

Edit!! -> Ok Peter, right... I thought it was better to ask specific questions in separate posts.
I also try to make subjects with specific titles, so that the answers could be found later on by newcomers.
So I did not make a post with "all about my project" before.
Am I wrong and should I make a post for going from A to B in deciding what i should do?

So ok, I keep this post with my climate specificity as a guide line!

Original post -> Hi all
RMH seem better adapted to cold countries...
- The draft seems better when the weather is cold for example.
- The heat arrives later in the night.

I think there can be two problems to overcome in warmer place. This still stucks me in the project.

1- Will the draft be enough when there is no big temperature difference between inside and outside the house?

At the same time, I live right at the foot of a cliff, so I cannot have a long exhaust pipe above the roof!
1st issue: I would like to know what I must be careful about, so that I keep a good draft.
Even with a few degrees difference with the outdoor:
- Is it still possible to have pipes UNDER the rocket level?
- should I reduce the pipe length?

2- I am subtropical, and I want heat at sunset, because the temp drops just at this moment.
(Do not say this is not cold! When you are used to the heat of the day, then it is cold when night starts!)
I am not interested in having heat at 3am!!!

Then about the 2nd issue, having fast heating....
- Is it possible to have a pipe with no bench?
The heat will be released by radiation from the pipes...
Will all the heat be released as efficiently as in a thermal mass?
Will I loose more heat?
Any other difference?

My Rocket is planned in a space (1m / 3 feet long) between 2 rooms. I have planned the feeding (with a window) in the living room, then the barrel showing in the coldest place, the kitchen, and I want to heat the living-room with the pipes coming back from the kitchen.

Thanks for advice.

Temperature difference of a few degrees is sufficient to get the draft going. I've no experience with dwellings at the foot of a cliff, although I would think as long there's no opening at the back of the house it would work. In other words, when the house itself is built against the cliff.

A suggestion: you are not interested in a mass heater, so your rocket stove should have no mass or at least as possible. Try this: the rocket and barrel in one room, and another barrel in the other. The exit of the first barrel at floor level, the inlet and outlet of the other at floor level as well. As long as those two openings in the second barrel are located at opposite sides, not beside each other this barrel will become hot as well, not a shadow of a doubt about that. This is called the bell effect, a concept some people here on this forum find difficult to grasp (or so it seems).

Xisca, when would you start to build a try-out version outside? You are asking a lot of questions all the time but no signals of ready stoves yet.

Yes I am against the cliff, and I should say under the cliff.
I have made a sort of rocket for this winter, without oildrum, and I could cook with it, but this has not the shape of what I will need!
I have lost my usb card transfer for posting new pics of plans...

Each time I have an idea, there is nothing to answer the new questions in the rocket pdf book I have.
And each time the idea was not good and I had to go back to brainstorming!

I am quite in a good place for the wind, coming from both sides alternately.
When it comes from above, then it is a tempest!! Una tormenta de 2 días...

A RS is supposed to work better when the weather is colder, doesn't it?
So I thought it would work WELL ONLY if I reduce some goals such as bench/pipe length, going down underground for floor heating etc.

Peter Berg wrote:A suggestion: you are not interested in a mass heater, so your rocket stove should have no mass or at least as possible. Try this: the rocket and barrel in one room, and another barrel in the other. The exit of the first barrel at floor level, the inlet and outlet of the other at floor level as well. As long as those two openings in the second barrel are located at opposite sides, not beside each other this barrel will become hot as well, not a shadow of a doubt about that. This is called the bell effect, a concept some people here on this forum find difficult to grasp (or so it seems).

After reading twice, I think I grasp it...
There is a feed tube, then the normal barrel, then the normal ashpit, and then, instead of a pipe, I would put a second barrel, then a second ashpit.
Then finish afterward as if it was the only barrel...
Does the second barrel need to be insulated the same inside?

If you have a link already talking about this without repeating yourself...

I agree with the idea, and I have to think about a room problem in the first room...
Also, hasn't the naked pipe the advantage of releasing heat farther on?

Xisca Nicolas wrote:Does the second barrel need to be insulated the same inside?

Not at all, the second barrel doesn't contain a riser or insulation or whatever, it's completely empty.

Xisca Nicolas wrote:Also, hasn't the naked pipe the advantage of releasing heat farther on?

I don't see any advantage. There should be a short run of pipe between the first and second barrel. Since each barrel is in a different room this pipe would go through the wall.

During the weekend I have some time to spare, I will make a simple drawing so you should be able to check the different parts.

I am going to try to explain myself better.

A barrel would be very much at 1 same place in the room whereas a pipe would spread heat more evenly into the room.
That was the advantage I was seeing.

I suppose that the 1st barrel will be hotter than the second one.
I have planned the fireplace in the room that needs less heat, and the barrel in the room that needs more heat.

The "wall" is 1meter thick and I had planned the barrel in a sort of tunnel in there.

Here is the 1st try.
And it shows the kitchen where i want to put the barrel: behind the actual RS, in a place we still have to dig in the rocky earth behind...

The place where the above RS stands. Roughly where the green post on the right stands.
See the entrance under the arch on the left.

From another angle...
The kitchen is on the right, you can see it through a square window (separating the entrance from the kitchen.)
Through the round window, you can see the main room.

2 points: The kitchen will need more heat as it is more on the outside than the living-room.
And I would like to see the fire in the living room.

BTW, about this nice stone called TOSCA, that we can sculpt...
It was traditionally used in ovens, because it is light and insulate quite well.
It is volcanic, and does not explode with heat.
It is porous to water.

I want to use local materials of course.
This stone also exists as "picon", which is the same stone reduced into gravel.
If I want perlite or vermiculite, I must import it.

The main room inside. You can guess with the mezzanine that I do not want convection and hot air above!!

The rocket's mouth will be on the right, under this arched place.
This is near the entrance, just on the opposite of the kitchen place.
We have to dig 1 meter between the 2.

So, here is the idea so far:
- Feed tube in the living room, with a window to look at the fire
- Barrel in the kitchen, just fitting into the wall
- pipes coming back to the living room for some heating.

I can also have a pipe in the kitchen, where i can make a little heated bench.
So, I would very much like to make a 2 pipes system.
I saw this in a video from a RMH in a yourte.

And I saw a video with Erica showing the possibility to use a "key" to close one pipe while the other still goes on.
My goal would be to stop heating inside while still heating the kitchen...

Xisca,
Answers in no particular order:
The two pipes system is used definitely as one OR the other, i.e. one pipe at the time. Difficult to implement, prone to malfunction.

This volcanic stone could be very well suited to a rocket stove because it's insulating itself.

A window in a rocket, especially your first build is bound to be very troublesome to get right. Unless you are implementing a horizontal fed batch box rocket, but that's quite another animal.

A bare pipe system will take up a lot of space, a single barrel would spread the heat just as easy, nothing to gain here.

Yes, a second barrel will be not as hot as the first.

The burn tunnel should be as short as possible, 70 cm will be way too long.

All your wishes cannot be fulfilled by one and the same stove.

The rocket in the living room, the most of the heat in the kitchen via a barrel which is built inside the wall, and a piped system back into the living room again. Try to make your stove less complicated, this doesn't sound as a viable plan.

Here's the sketch of the double barrel system. The red line is the direction of the gas path.

schema

Thanks Peter, I was coming to the conclusion myself that I should make 2 RMH (though I did not want to...) , so you help me about it!

I can plan to warm water with the kitchen's rocket!

New project now:
- I have made a plan and it suits me well, I will share soon.
- I plan a rocket with local materials, and I hope I can even make it iron free. The masonry should even be easier, as there will be no difference of dilatation (as between mineral and metallic materials).
BTW, Tosca is tuff.
Ans I also have basaltic grey stone. I think it also resists the heat.
- only radiation heat, so that I will have little convection effect (that would make too much heat in the place where I sleep above).
A good radiation should allow me to afford the strong ventilation I need to dry the winter humidity.

About the double bell: your schema is what I had imagined, except for the movement in the second barrel! I guess it goes up because of the heat...
Can you tell about a maximum length of pipe between the 2 barrels?

With my new plan, I make a very ordinary RMH ...but a few details!!

It is very normal because it has no glass window, a J shape, a straight pipe to go out...
the goals:
- Get a maximum of cool radiation and as little convection as possible
- Warm the floor
- Use local natural materials as much as possible

Specificities:
- It will be quite underground!
It will look as if i was making a fire in the floor!
= the top of the feed tube at floor level.
-> no more glass window needed to look at the fire

- It will be in the middle of the room, facing the sofa...

- Then the pipe will cross the room underground (max 3 meters long)
It will be insulated below, with tuff stone.

- The tuff heat riser will be surrounded with stone instead of an oil drum,
it will look like a big seat in the room.
It should all resist high temperature, as they are volcanic stones.

- I will make a trench on the side of the barrel, so that I can make the 2 cleaning access.
This will be covered with a plank.

- the pipe that goes underground will go out through a stone wall (the hole is already there, just at floor level).
So, this pipe (or stone galery, if possible...) will slowly goes up from the RMH to the outside. Thus I will be able to do the cleaning from there.

As this is quite short (total 4 m max, straight and one way), I think I can still make a little 1m bench there, before the pipe goes up and out.

Well, it looks (as read in another topic) as if I cannot make a RMH without the METAL barrel?

Some problems come when one cannot do the EXACT plan in the book. All questions in this forum show that some answers cannot be found in the book! I really wish the most experienced people would gather for re-writing something...

If the metal is needed for cooling down the hot air, then why have I also read in the forum that it is possible to cover it with clay, so that more heat can go into the mass?

Has building with bricks instead of a barrel really been tried or not?

A collective book would certainly work.
Some people are good at doing, but not good at transmitting their experience. Some are better in writing, some in organizing a logical plan and order in giving the information... It is not usual for me to have to ask so many things, as I am usually quite good in self-teaching through writings. Do not see any critic of the people that are trying their best to make this technology best known. I share the mess in which I find myself so that I do not give up. I also want that more people do it, and I think it is necessary to share honestly the labyrinth in which one can be found.

Here is what happens to me when I have a question: all informations are scattered in different parts of the book, they are not always under explicit chapters' titles, and it is very difficult to find again something I was sure I had read somewhere. And when I find an information, I usually feel as if I had a recipe with 4 eggs that does not tell me if and why it will not work with 3.

I have a much better access to free local natural materials than scraps, so I am looking for a permacultural solution!
I could finally get an oil drum.
I burnt it.
It went out of the process with all its paint but was no more round, the bottom just with no more shape.
It is all buckled...
At the moment, doing a RMH, buying a metal cylinder, buying all the pipes for inside the bench, will just cost more than a small simple cast iron stove coming from east Europe, which more over has no building cost!

A RMH build with local materials, that can be done again by everyone even in an island when what comes from outside will be impossible to afford anymore ...that would be so great...

Xisca,
A couple of days ago you stipulated that you didn't need slow heat. Now you are looking for ways to make the whole of the rocket stove out of stone and brick and tuff. This will result in a stove which is quite slow to warm up, what do you want, quick heat or slow heat? The metal barrel will radiate as well, but at a higher intensity,

It is possible to build a complete rocket including barrel out of stone-like material. You do need to bring the temperature down inside the "barrel" though. Making this quite a bit larger would be a way to achieve that.

Covering the metal barrel in clay will result in less cooling of the gases impairing the drive of the stove by that. This can only been done when the chimney stack is a real good one. A couple of years ago, I have built a rocket inside a single bell of bricks, about twice as large as a 50 gallon barrel. This did work very well, no doubt about that, the stone barrel have to be larger or utilizing a real good chimney or both, that's all.

It's perfectly possible to build a stove in the floor, it has been done before. But... you are (again) unclear about where the barrel-like construction is located relative to the feed tube. Make up your mind and ask pin-point questions, nobody is going to design a stove for you, you have to do this task yourself...

I do like that you are pin-point Peter!
I change my plans according to what I learn & my mistakes.
And I have imagined many designs already...
I thought I had to give up the "natural local material solution", and I would be delighted if this was possible.
Without being stuck by a 100% ideal dream either...

I wanted strong and fast radiation for 2 reasons:
- I did not think that it was going to produce more convection, which is bad for me.
- I compared to neighbours houses' needs, that are NOT insulated at all. So they do need to raise the temp when they come in after working outside.

So I was convinced by slow radiation, as this person from Texas was stating for his climate.
Also, this allows me to heat AND make a lot more of air circulation with still a lot of comfort.

I hope I can make a "real good chimney". Do you mean high? If the barrel is larger, then the exhaust must also be larger afterwards?

Peter Berg wrote:It's perfectly possible to build a stove in the floor, it has been done before. But... you are (again) unclear about where the barrel-like construction is located relative to the feed tube.

I think you mentioned this before, but I dropped long ago the idea to have the wall between the barrel and the feed tube.
I have learned that it is important that they are close one to the other.
That is why I had the idea to make an alcove in the wall.

So, this is all "normal", they will be as close one to the other as possible.
Everything is "normal" but the down-floor, and my try to avoid metal in favor of local and free material.

I am delighted to go on with the idea of stove in the floor, thanks to the idea that I can have the trench beside the stove.
Look at the spanish "gloria"
http://www.youtube.com/watch?v=_56kBTezrs0
I was also fascinated by the roman hypocaust...

I am reassured by the solution that I "only" have to do it larger.

Xisca : Good luck with your future work on retro fitting an in floor heater to your home, this is usually a project where the heater is made, then the
house was built up around it ! it will be good to see the early attempts to duplicate this build outside before you try it indoors !

For the good of the Craft! be safe,keep warm, PYRO Logically Big AL

Thanks allen!
Peter helped me drop the idea of making 2 things with one RMH already, and I will drop any idea that gets to a deadlock,
...but if success has many parents, then the parents are here!

About my house: It has no floor yet! And we use the ground with lime or cement for stone walls... This is not earth.
This house is 60 years old, originally all made with lime and stones under a cliff overhang.
We removed the old stone floor (impossible to clean it) and I work with local bricklayers. They are very good with stones.

I hardly see how I can build it outdoor first if it is not of bricks as
- Bricks have interchangeable places.
- Bricks are square and stand up without mortar.
- Bricks do not let so much smoke go through.
- how will I mimic then the pipe and the chimney, as they are more essential for a draft with no oil drum?

At the moment, let's consider if I can go on or not with the idea. I think the next step is to know what are the criteria of the chimney I need. I think I can go up to 4m high but this is along the cliff. Wind comes from the sides.
If I have to, of course I will buy an steel cylinder and have a top welded.

Hi!
We are going to dig the house ground soon!

As I lack information about an all stone design and the chimney for a good draft etc, I have decided to go on with a welded iron cylinder with a top, so same form as a barrel.

If I put some tuff stone on top of the barrel, to limit the unwanted convexion, I think that iron sides will be enough for the needed radiation. It will lower the temperature of the barrel and create the needed draft downward. I hope that the needed cooler part is not best on top of the barrel!

- I will put an air pipe at the feed place, for more oxygen. I can make it pass under the outside stone wall.

- I will also put some tuff under the rocket, for insulating. This will certainly be covered with some lime, in order to get a flat basis for the building.

Xisca N.: I finally understand that it is important to you to build your Rocket Stove with as few pieces of material that would need to be imported, You want to build something
That your neighbors can copy and use ! That is a Great Idea and you should keep trying to make that happen, I will help all I can !

When I sent you a post about building A Rocket Stove outside, I wanted you to create your Rocket stove outside FIRST, and test It there and prove to yourself that Your
Model of A Rocket Stove is going to work, this includes the use of a barrel, and as much Pipe with all the elbows in place as you will use when you bring the Rocket Stove inside!
After you can get it to work outside is soon enough to think about moving it inside !

You talk about putting ''tuff'' under the rocket for insulation. In English we have a word close to this, ''Turf'' which means grass, you don't want to use grass so I need you to tell
me what is the right word ! Don't you have pumice rock ? Volcanic rock so light, some of it floats ? That would be fantastic ! The lighter the better, a little clay slip to hold it all
together would be all that I would add to the pumice !

Remember, for the good of the Craft! Be.safe, keep warm! - PYRO Big AL - As always All comments/questions are encouraged and welcome !

allen lumley wrote: You talk about putting ''tuff'' under the rocket for insulation. ... tell me what is the right word ! Don't you have pumice rock ?

Hehe, I can teach about an English word!
http://en.wikipedia.org/wiki/Tuff
This is not as light as pumice, and softer.

See the red stone in my photos, the one for the arch.

allen lumley wrote: Xisca N.: I finally understand that it is important to you to build your Rocket Stove with as few pieces of material that would need to be imported, You want to build something That your neighbors can copy and use ! That is a Great Idea and you should keep trying to make that happen, I will help all I can !

Thanks sooooo much!

I can tell you that I see some cultural differences between the US and my place, about what is being ecological or local!
When I see people promoting making biochar with pellets, this is just out of place in MY place for example!

Local people here do not buy stoves, and some of them are just so cold in winter, which is rainy. It is not freezing, but it can be half of what you expect for being comfortable inside. 10°C is just not enough inside.
Foreigners have stoves and stoves are imported from Europe, as everything...
Some people just have electric heaters...

Permaculture is about looking at what is locally available in the place.
An oil drum is not a good idea here. They are difficult to find, and reused for other purposes here.
And they begin to be collected as returnable goods!!!

In the book, the use of an oil drum seems inevitable, nearly inescapable.
This is great when there are so many that they have become a nuisance and need to be recycled.
So, when one wants to adapt oneself, then some information is not really emphasized.
This is what happened to me about the importance of cooling through radiation and convexion from the METAL.
It is not stressed.
What is emphasized in the book is the insulation of the internal mouth and heat riser.

allen lumley wrote: When I sent you a post about building A Rocket Stove outside, I wanted you to create your Rocket stove outside FIRST, and test It there and prove to yourself that Your Model of A Rocket Stove is going to work, this includes the use of a barrel, and as much Pipe with all the elbows in place as you will use when you bring the Rocket Stove inside!
After you can get it to work outside is soon enough to think about moving it inside !

I will try if I come to the conclusion that this is possible, and I explained why it might not be, as far as I can see.

If I replace most of the refractory bricks and the metal pipes by tuff and some mortar (clay or lime or refractory cement, let's see afterwards)
then I will have "holes" as long as the mortar will not be there.

That is why I also look for a model that is very "normal" in as much criteria as possible.
I have come to an idea with no curves at all between the barrel and the outside, and with an ever ascending path.
I can also add a little tunnel that will bring fresh air from outside, just at the feeding mouth.

Xisca N. : Building your Rocket Stove as an Exact Build, but Outside, just the way you plan on doing it inside your house is a Safety Step and should always be your first step
after you get all your parts and pieces together !

It is a great self-teaching step and where you should start taking lots of pictures that you can refer to, saving you time on the build, not only are the materials at hand, you
have stacked them up easy to find! I have never done one of these builds where the help I wanted, matched the actual help I had, this step will always save time!

I understand that you are concerned about how to do a pre-build without mortar, and I am glad you wanted to talk about it ! The answer is in two parts, and both can easily
be forgotten by other builders as we try to explain exactly how to build your Rocket, #1) always remember to soak your bricks in fresh water before using them! !

How long depends on how clean and dry the bricks are. This is the step that keeps the Dry bricks from sucking so much water out of the Mortar that the Mortar dries out
before it sets ! Only trial and error will tell you how much soaking each batch and type of brick needs!

#2) Is also a step that needs to be practiced before your Final build, you need to have 6-8 liters of clay slip mixed up, and stirred regularly, it should be thick enough that
when you poke it with a finger it leaves a dimple in the top of your clay slip that stays there a little time, but dry enough that the hole it leaves has no shape, if you pick up
the whole bucket and then drop it, Your dimple disappears !

I am taking the time to explain this well because you are going to take each PRE-Soaked brick, and dip it into the clay slip, to get the sealing coat that you will use for this First
build! For this build you will not use mortar, After you have done this step once, you can use this trick to help in future builds! Always test a new technique before you use it!

This will also give you a chance to practice in your smoothing technique for the internal walls where it is important that these parts be smooth !

I have found again and again that the time I take preparing my mortar, is time and materials that I save! The mortar is mostly there to keep the bricks from rocking as you
stack them one on top of another, also to make level* each course or layer of bricks!

You want Builders Sand, which is grittier than regular or beach sand, Sift through the sand for over-sized pieces!

If you go with a Lime Mortar and you find that you have made a mistake, you can take it back apart, don't use Portland or Refractory Cement here, Portland can't take the
heat, is hard to clean up so that you can re-use your bricks. Refractory is too expensive to use here and not needed except where you want durability and strength, like
around your Feed Tube ! ( The bricks that you save will be your own!)

A final thought on the Barrel, Yes it's a necessary evil, but think of it like this, you are not just recycling the Barrel, you are UP-cycling the barrel !

For the Good of the Craft! Be safe, keep warm! PYRO Logical Big AL - As always all your comments are solicited and welcome ! A. L.

* don't forget to check all 4 sides to be true and vertical also, this will make adding insulation to the Heat Riser, and setting the barrel possible ! A. L.

If I build with bricks and pipes, I will make a trial.
My problem will be to do it with tuff stones.
Bricks are all the same and can change place in the building. A stone stove will be like a puzzle: each piece has its own place.

http://www.youtube.com/watch?v=azHuJFg3bFE
A short web4deb video with a feed tube in the ground!
His double feed tube looks interesting for collecting ashes.

Xisca : I understand about the Tuff stone that you want to use, I would try to find a square-ish dry 'Tuff' stone, And make up an equal amount of Cob. Bake the cob
and weight the two! the heavier one is the one that you want to use for your thermal mass.

If the 'Tuff' is heavier then the Baked to dry Cob, then use it every where you can get away with it , using just enough cob to hold it all together! If the DRY Cob is
heavier than the Tuff use that most!

You really need to plan on finding enough bricks to make your Heat Riser, odd sized pieces of uneven stone shaped/held together with mortar and Finishing with a Preset Constant
Cross Sectional Area even if you make up a form to build up against, is a job for a very good mason ! !

Failing in having enough bricks to make a heat riser, I would always fail back on making a form out of two pieces of stove pipe, and stuffing the gap between them with
Perlite/vermiculite and clay slip ! Hand laying up rough shaped stones would be a very distant 3rd !

For the Good of the Craft! b.s., k.w.! PYRO AL - your comments welcome !

The hole has started in the ground today!

I work with a good mason that is used to work with stones!
My 2 types of stones can be seen on my photos.
Apart from tuff, I have heavy stone that also resists heat, and conduct better.
Clay will come from another place, still have to look for it...

My planned use of tuff:
Tuff can be cut with a circular saw.
Tuff used to be traditional here for bred ovens.
I was thinking about it for all parts that must be insulated:
- the burn tunnel
- the internal chimney, the heat riser.
- insulating: below the RMH and on the underground sides

The alternative:
refractory bricks close to the fire or gazes + tuff outside, for more insulation.
I must verify the quality of my tuff for cutting it smooth enough.

Drawbacks:
- the best tuff for cutting it smooth is also the heaviest, so less insulating.
The light one falls appart more easily! I have just experienced it today while I was cleaning some pieces with pressured water...
- I have no idea how insulating tuff is. I do not know how thick the heat riser will need to be.
(but with the iron cylinder instead of the barrel, I can chose the diameter)
If some people make the heat riser with no more insulation than the refractory bricks, then I think that tuff will be ok.

My planned use of heavy stone:
This stone is heavy, is also volcanic, does not explode in a fire. It becomes hotter than tuff in the sun.
I can also have large flat pieces, because it splits better in one sense than the other.
I was thinking about it for all the parts that must conduct heat:
That is to say everything after the barrel!
- the ash and gaz collector,
- and the gaz duct,
- and above up to the ground level.

Xisca : As a suggestion from me to you, Please go to PERMIES Rocket stove Forum, and look at Thomas' V.s Thread - "" a castable burn chamber "", ann click on
his you tube link.

I would strongly recommend that you consider the idea used to make the core in the video! Which is to create a wooden form for the inside of your Heat Riser,
something that can be taken out after that part has been made! It is very important that you keep a Constant Cross Sectional Area through out your Whole build !
Also you will want to keep the smoothest side of the stones to the inside of the Heat Riser !

Talk to your Mason and make it absolutely clear to him that you want the C.S.A. Or interior area/volume to stay the same through out the building of your Rocket
Stove Base !

You have not shared your plans for how you are willing to make your internal piping with in your Thermal Mass! I can not believe that you can hire a Mason to craft duct
work through your Thermal Mass for less cost to you than you building it out of light weight metal ductwork and cover it with Cob and Rocks, and what are you going to
do if there are problems with some thing that will then need to be dug up out of your floor !

For the Good of the Craft ! Be safe, Keep Warm ! PYRO Logical Big Al - as always, your questions/comments are Solicited and are welcome - A. L.

Yes this is a good idea!

he uses Fireclay, but says it could be any clay. Then he mixes with Perlite.
He says this could be replaced by wood ash or other organic insulators...
Then this is cob (clay + straw), isn't it?
I can get vermiculite, but I must add 20€ per bag for transport....
Straw comes from peninsular Spain because we do not produce it...
I can still buy some...
Dunno if ashes are really good... or what else...

About internal piping: Clay and stones are for a bench, because one needs to form it.
I do not need to give a form to the thermal mass in the ground.
So I have planned to put tuff at the bottom and then to put back some sandy ground as thermal mass.

Then for the duct, it will depend of the costs of what I will buy. No way to recycle materials!

Xisca : I remember watching a documentary on the Canary Islands, where An excited Commentator voice told us that the Western side of one of the Islands was in
danger of sliding off of the Island, and into the sea where it would create a large Tsunami capable of endangering the East cost of North America !

He explained that certain types of the Islands Rock were so porous that water could easily leak thru it especially if it had been exposed to superheated volcanic steam.
Is it possible to get some of this kind of light-weight volcanic rock ? ( It has to be light if it is that Porous ! Am i right or Wrong !

Yes, you could use any organic ash, Ashes from any commercial heating plants operation, using ether coal or coke, and dumped on the ground in a dump pile some-
where could also be used for insulation but of course some would find this use dirty or uncool, and even now many years later there might be some pieces that still
have a sulpher-y rotten egg smell ,not what you might want in a home !

If I had a choice and the money was the same, I would go with any type of perlite over vermiculite, you might find that a local greenhouse operator can get you a
better price than you can get any place else on your Island!

True professionals can always 'float' the surface of the Cob ending up with every single strand of straw buried just under the surface -( The last few can ether be pulled-
out, singly burned off, or covered with a nice 'White on White' finish coat with a Finish Lime Plaster !)

I can only recommend that you try to find a light weight stove pipe,as a round pipe should better flow the hot exhaust gases and transfer the heat energy to the Thermal
Bench, better than a square ductwork made out of the smoothest stone and sealed with lots of care to keep the internal walls nice and smooth!

For the good of the Craft ! Be safe,keep warm ! PYRO Logically Big AL - As always, your comments and questions are solicited and welcome ! - A. L.

allen lumley wrote:.... the Western side of one of the Islands ... a large Tsunami capable of endangering the East cost of North America !
... certain types of the Islands Rock were so porous ... Is it possible to get some of this kind of light-weight volcanic rock ?

- This is my island... But the south west and I am north west.
- So I can inquire about this stone, as I do not know it here.
- And this news about a tsunami was more or less a hoax!

allen lumley wrote:Yes, you could use any organic ash, Ashes from any commercial heating plants operation, using ether coal or coke
... still have a sulpher-y rotten egg smell, not what you might want in a home !

I would go with any type of perlite over vermiculite, you might find that a local greenhouse operator can get you a better price than you can get any place else on your Island!

Here is the unbelievable local difference!
Imagine...
We stayed 3 months looking for hydraulic lime because the shop would not have it again until they finish selling a lime mortar... Now we have it from another shop (better and cheaper, yeah!), though now we have to wait for the next boat because they did not buy enough...

So... There is ONE heating plant, the electric plant burning petrol...

And... the only place where I could find vermiculite (1 lb bags for 2€....) was the shop selling everything to cultivate marijuana seeds! Then the big material shop can import it in big bags.

So straw looks better than ashes doesn't it?

allen lumley wrote:I can only recommend that you try to find a light weight stove pipe, as a round pipe should better flow the hot exhaust gases and transfer the heat energy to the Thermal Bench, better than a square ductwork made out of the smoothest stone and sealed with lots of care to keep the internal walls nice and smooth!

Ok, This I understand that the duct should not be insulated (for transmitting heat to my floor) and as smooth as possible.
Instead of square, can we also cast it (round)? I have planned only one straight pipe and no curves.
And I do have at home (yessss!) a very big plastic PVC pipe.
Of course instead of clay and perlite, this could be lime with heavy stones around...

I should ask again for the pipes' prices so that you get an idea. They come from France! The canary used to be traditionally stove-less and the houses cold in winter. There were only chimneys in the kitchens.

Thanks for helping explore the possibilities!
RMH are great, and really adapted to a "post-consuming society" with trash around.

And I really touch the adaptive and "not one solution" of permaculture.
The scientific laws of any material stay there, but the solutions vary a lot.

And the big hole in the ground is waiting now!
The ground was rocky enough, it will be strong.

Xisca : On May 6th, in an answer to Peter Burg you talk about '' the book ", can I assume that you have a Copy of Jackson and Evans' Great book
'Rocket Mass Heaters' ?

I am afraid that in your case a certain amount of information that you have used to create your design schema/scheme is made of designs from You Tube,
or other suspect sources, I stand by my promise to help you craft your Rocket stove out of locally procured materials, and will take it on faith that your
mason is both capable and has a design plan to keep a carefully crafted Constant Cross Sectional Area, and He understands that the interior walls
through out the whole build needs to have very smooth walls and he most Craft them!

It is your Responsibility to Totally understand the one most basic requirement in the construction of Your Rocket Stoves - Internal plumbing, its
'' CROSS SECTIONAL AREA '' This must be kept wholly constant through out the entire Rocket Stove Build, otherwise you are creating a non-
working sculpture - rather than a working Rocket Stove !

I want to refer you to the '' Dimentia and Proportia '' Section, page 35, in Your copy of " Rocket Mass Heaters ''! Where it explains that regardless of how
you construct Your Rocket Stove, all the internal plumbing parts MUST have the same Cross Sectional Area CSA ! This includes the Feed Tube, the Burn
Tunnel, and the Heat Riser ! as well as the Cross Sectional Area CSA, of the inside of the pipe used as a form inside the Thermal Bench ! This must be done
every time, every place as you move from Square, to Rectangular, and to Round !

After all that we have discussed, about how you would make this, and of what material you will make your system out of - I have to ask you, what are your
plans NOW for This '' very big plastic pipe '' (?), you have to understand that this type of pipe is insulating, and it will melt if used inside the bench too close
to the Rocket Stove ! Also attempting to use this piece of pipe makes it the single controller of what size the rest of your stove gets built to, even if that
means Your Stove will be too large or too small for your Actual wants and needs ! What is its internal diameter, and how long, and does it have 'specially -
shaped ends' ?

Straw, While using straw will indeed make your cob a little lighter, it is there to make the Cob Stronger - in exactly the same way that metal rebar makes
Concrete stronger, using enough Straw to materially lighten your Cob will weaken your Cob. Talk this over with your Mason And make sure that the two of
you agree on this ! You can always make a set of bricks to test this if you need to actually see this !

Please advise! For the Good of the Craft! Be safe, Keep warm! PYRO Logical BIG AL - As always, all comments/questions are encouraged and welcome! A.L.

Great, this is wise to check out the basic and be sure about it!

allen lumley wrote: Xisca : On May 6th, in an answer to Peter Burg you talk about '' the book ", can I assume that you have a Copy of Jackson and Evans' Great book 'Rocket Mass Heaters' ?

Yes I do have this 99p pdf! They are preparing the Spanish translation...
I also have the French adaptation as a paper book.
It did not help me enough for adapting to the situation, so of course I did go a lot on youtube... and read a lot here in permies.
P 45 shows a heat riser with bricks, and then here I can read that some tried it, and then tried metal with rock-wool inside, and that he finds it the best insulation. So yes there seems to be means to carefully choose what to do.
And every detail can make a big change, sometimes not...

As I have found a good place that will be near a wall (what a pity, we had already limed it!) and as I will buy an iron tube, I can choose the hight of the heat riser.

If I am right, I remember that it is even better to have a higher internal chimney in the system.
I also think it does not change any of the other parameters.
I will mainly gain draft.
Am i right?

allen lumley wrote: CROSS SECTIONAL AREA '' This must be kept wholly constant through out the entire Rocket Stove Build"
every time, every place as you move from Square, to Rectangular, and to Round !

Yes I do have this in mind, including the different shapes.
BUT, I thought that the more we get away from the entrance, the more the CSA can be a little wider. Never narrower.
My conclusion after reading and reading again p 33 and 34, is that the dragon mouth should be anyway the smallest.
It is also possible to shut it partially when lighting the fire.
My conclusion was to make it at least very even, or even better slightly widening but NEVER never reducing in any part.
I also thought that widening a little was a protection against any accidental or normal narrowing due to ashes or any crust forming inside.

allen lumley wrote:what are your plans NOW for This '' very big plastic pipe '' (?), you have to understand that this type of pipe is insulating, and it will melt if used inside the bench too close to the Rocket Stove ! Also attempting to use this piece of pipe makes it the single controller of what size the rest of your stove gets built to, even if that means Your Stove will be too large or too small for your Actual wants and needs ! What is its internal diameter, and how long, and does it have 'specially - shaped ends'

1) It is 8 inches. I said that the planned duct went straight away because I want to take the plastic off when the lime or clay will be dry enough to stand alone in the trench. I was also thinking it was necessary to make it in more times than one.
To better the draft, my idea was also to slightly go up:
so the duct will be at surface level just on the other side of the wall, and it will be possible to pull out the plastic tube.
I guess I will have to put some fat on it!!

2) Yes I realized that any fixed choice about any inner part is the controller of the rest of the system.
So I might have to drop some ideas when I have 2 contradictory ones.
I am still calling the blacksmith and still do not know the cylinder diameters I can get...

3) It is very difficult to know the needs, except that the fire can be shorter if the system is too big.
I have a clear preference for a big system that I use shortly.
1) If I do not have a large system, it is not possible to make a bigger "mouth" for CSA reasons
(oops, I love fire, and this opened fire in the ground will be the luxury of my simple life!)
2) My underground duct will be 4m long (12 feet?) which is not long.
3) Then it goes out in a semi opened kitchen, where I will be able to make the outer chimney.

So if my underground system does not beneficiate from all the heat, and if more heat than it should is still available when it comes out in the kitchen, even better! I can have a piece of bench there, before the pipe goes up and out.

I forgot that straw was for strength... I must definitely find this light stone. Ianto says that pumice is great for insulating, I hope we have a similar local resource!
Then he says that horticultural perlite is not as good because it will suck too much water.

Xisca: Great ! as long as you understand that you have to honor the CSA and keep it Wholly , Good luck with removing the pipe after you use it for a form !

I think that Ianto Evans meant that the non horticultural perlite was preferred over the horticultural perlite, not that it could not be used, i believe it is also slightly
dustier, but still not as water absorbing or dusty as vermiculite !

The bottom picture on page 45 is actually a picture of the Transitional area just below the barrel where the hot exhaust gases make a sweeping right angle turn
to the horizontal, and are funneled down to an 8'' opening, here is where you will want an 8'' 'tee' with a clean out cap !

Yes a higher Heat Riser well matched to its barrel will always have a great draft ! As long as you are trying to keep the interior walls as smooth as finish plaster
and only make slight/small changes to your CSA, I think you will be fine there !

While I like lime plaster on the finish coat, plain Cob without any straw will make THE BEST material to be in direct contact with the piping and will be much more
removable if you have a problem - like a stuck pipe !

Good luck PYRO AL !

allen lumley wrote:Xisca: Great ! as long as you understand that you have to honor the CSA and keep it Wholly , Good luck with removing the pipe after you use it for a form !

Argh, you mean we will certainly not be able to remove it?

About p45, do we have the same ebook version? It says:

A good example of a brick tower under construction
in Chris and Jenn Reinhart’s house.
A fortress of brick is mortared in to support the barrel.

As I do not know clay at all, this is difficult for me to judge it better than lime. I have not inquired about lime adaptability to heat...

Xisca : I never have tried to remove a pipe after use, I just used old metal stove pipe off of the scrap pile and never worried about getting it out ! This is new
Territory to me ! I suppose you could use the pipe to make 1/2 round Cob (with some lime for more durability/strength?) sections of pipe that will(?) have the
outside diameter of the pipe for its inside diameter. Two Cob 1/2 Rounds can be made with flat bottom sections and stack well together to make a whole !

No, different pages, thats my page 47 ! So what I was talking about was probably on the bottom of your 43 ! Most everyone who still builds a Heat Riser /
Internal Chimney out of brick has to fill in the space between the bricks and the barrel to get the 2'' gap that is generally recommended, they use either the
rock wool or the perlite and clay slip !

They generally use the outside metal skin off of the outside of a hot water heater to hold in the two types of Insulation, I would check with local plumbers and
see if they have not replaced a leaking hot water tank for an upscale client ! They come in many sizes, and a few holes in the water heaters main tank will
only need to be gas tight not water under pressure tight ! After the tank is drained it can easily cup up with a grinder or a cutting torch, there is even a very
common model in most of Europe with the heating element in the very top which you will cut off !

Lime is an excellent material to add to the Cob to make a finish coat, as is gypsum ! However, as it makes a harder finish material it is difficult to rework the
material if you find you need to make a change ! Regular cob can be scraped out without damaging other materials that it is in contact with ! It can also then
be softened and reworked just by soaking it in clean fresh water ! Lime makes better mortar than portland type cement ! It does not dry as hard, making the
bricks easier to recycle !

Good luck with your hunt for lighter weight Pumice/Volcanic Rock for more insulation !!

For the Good of the Craft ! Be safe, Keep warm ! PYRO Logical Big AL ! _ As always, your questions and comments are solicited and Welcome A. L.