Our Second Second Rocket Mass Heater

We finally decided to go ahead and rebuild our second rocket stove (the one in the living room). My primary wishes were to rebuild the core (better) and to convert the relatively useless mass into a (small) bench. Iulia decided to make it a workshop and …  3 interested people showed up.

During the first day we settled into being together. I left the existing rocket mass heater in tact so we could review its shortcomings together and learn from that. We talked about the basic workings of a rocket stove while talking about the existing stove.

… and then we took it apart:

We had only one wheel barrow of waste which was non-toxic and we dumped it as back-filling at the earthbag cellar.

Though there was some soot in the rocket (sometimes it didn’t burn completely clean) there was very little of it given that it worked for 6 winters. There was a 1cm layer of light and fluffy ash sitting at the top of the heat riser (accumulated over the same period of time).

Until we reached the brick platform upon which the rocket was built.

We then layed out the expansion of platform for the new rocket.

… and started building it … giving everyone their first experience at working with mortar and laying bricks.

The next morning we finished it!

With the platform done we built a mockup of the core (while learning about dimensions and sizing using standard brick sizes) and its place on the platform (and relationship to the bench).

We then settled into a rhythm in which two people were laying bricks (one working on the core, the other working on the bench) and two others were preparing soil for mortar and cob (and doing other support tasks such as cleaning bricks so that the brick layers could work smoothly).

As the chamber that is under the bench started to take for, I figured out how we were going to close the top of the chamber  (close from the chamber that makes the bench. The plan I came up with involved recycling two concrete slabs we had lying around together with some bricks. Next I had to figure out how to create a structure that could support that top while allowing a good flow of gasses through the chamber itself. It was a bit of a puzzle but we solved it.

… and the core was rising up

… and the chamber was rising up … and we were starting to apply cob (especially on the back side where access would become more difficult as the construction grew):

… and I think this is where we finished up on day 2:

On day 3 as most of the riddles were behind us and everyone had a better sense of the materials and the work, progressed flowed and accelerated. The core was completed and the chamber layout finalized. While the chamber was being closed up the heat riser was growing.

Pretty soon we were insulating the core with  perlite in a clay slip (recycled from the previous rocket) in the chamber built around the core:

… and then the insulation sleeve around the riser was put in place (recycled from the previous rocket) … and also filled with perlite:

… and finally the barrel came on (for the last time – we had quite a few fittings), we sealed all around it with cob … and lit the stove … and despite adverse conditions (a new rocket filled with moisture, on a warm summer day) we all smiled when we saw the flames getting sucked into the rocket and the dragon came to life. Very soon we were in an overheated room with a warm bench (that nobody wanted to sit on).

… in the excitement (and a bit of rush to accommodate the schedule of one of the participants) I missed taking a picture of the barrel on the “raw” rocket … but the next day (today!), with Liam’s help preparing soil and mixing cob, we were able to get much of the cob work done (and we may complete the rough structure tomorrow).

Even though it is using the same floor area as the previous rocket, the footprint of the new build is much larger … and it dwarfs the room … which feels a bit off. That is a price we’ve paid for having a warm bench to sit on (without taking on a much larger renovation).

It was an intense weekend. I’m glad to have had an opportunity to share rocket stoves with Tudor (missing from the picture below because he had to leave before we took it) , Dan and Liam and Iulia. I’m glad to have a good core with hopefully a comfortable bench for next winter.

2018 Rocket Stove workshop

Our rocket-stoves journey

We have a journey of rocket stove building at Bhudeva… first it was the first rocket stove (bedroom, 2011), then fixing it (2012) then the second one (living room, 2012) and rebuilding the first one (2014).

We cook food and bake on both rockets most of the winter time.

It’s time to try a next step – we are going to rebuild the one in  the living room, this time we are going to make it even more efficient and add a heated bench for two on it :).

We are open to make it as a mini-workshop where you can come over and learn by doing.

The workshop

We will be building a rocket stove with a small mass attached to it and a place for sitting / reading / resting. It will be an opportunity to learn what were the limitations of the previous design (and why they were introduced in the first place) and the considerations that went into the new design. We will be building a typical rocket core with an attached brick chamber with some cob to add more mass and bring it altogether. It is a tight design that will fill a tight space.

You will have an opportunity to:

  • Learn about rocket stove design,
  • Participate in all stages of construction,
  • Meet the materials and the tools involved,
  • Spend some time at and learn about Bhudeva.

All within the settings and limitations of a traditional Romanian village house.

The build/workshop is estimated to take place in 15-17 of June 2018. The workshop time is Friday (half day), Saturday (full day) and Sunday (until 16:00). If you’ll join us, please arrive sometime Friday until 13:00 (so we can have the second part of the day for working).

There are 5 places available for participants. Sleeping will be in tents (there is plenty of space).  The price for the workshop is 540 lei / participant. We are asking for 200 lei in advance (bank deposit or transfer), when registering, for booking your place. The rest will be paid cash at Bhudeva.

Please acknowledge that English is the communication language at Bhudeva.

 

Living conditions

We are assuming you will want to stay at Bhudeva, however there may be other options one of which is a new pensiune just outside the village (a few minutes drive) which has recently opened its doors to visitors.

If you do choose to stay with us, here are a few things you may wish to know:

  1. You will be camping in a tent (that you need to bring with you). We do not yet have built structures to house other people. We have one small house which is a private space and we prefer to keep is that way, for now.
  2. We have one composting toilet in the house. If you stay here for a few days or more, you will learn not just to use it (make contributions) but also learn to care for it (emptying it in our humanure hacienda).
  3. We have a small outdoor kitchen. We are inviting you too cook together or, if this doesn’t suit you, please bring your own food. If we will cook together, you are invited to bring with you some of the next produce: “bob lung” rice, spaghetti pasta, avocados, honey from verified source (we’ll coordinate this by email).
  4. We eat mostly vegetables and fruits, with some dairy productions and eggs. Most of it locally (in the village) produced.
  5. We intend to be doing everything together: working, cooking, cleaning. We’ll see how this flows.

Visiting Bhudeva, you are going to encounter also our solar dryers, earthbag cellar (we are now at the green roof preparation), hugel beds, solar panel or other things we play with and experiment here.

🙂

If you’re interested to partake please write Iulia at iulia [dot] sara [at] gmail [dot] com… in English and include your phone number and the questions you want to be answered before coming to the workshop (and maybe during the workshop, if you already have something in mind).

Iulia and Ronen

The Rocket Mass Heater Builder’s Guide

This kickstarter was originally planned for last year … its finally arrived. Until now there has really only been one book on Rocket Mass Heaters by Ianto Evans, but having read it and built rocket stoves guided by it, I feel it is out of date (though I haven’t seen the latest edition). There has been much evolution since this book was written and I am confident this new book by Erica (and Ernie) Wisner is a much needed replacement for it.

If you are new to rocket mass heaters and you get to the kickstarter in time (there are a limited number of places available) I recommend the $75 bundle which includes the Village Video DVD – which is the best I’ve seen so far and I have a feeling will compliment the book very well (since it also follows a build by Erica and Ernie). That bundle should give you a very good start towards building your own rocket mass heater.

Cooking on a Rocket Mass Heater (Rocket Stove)

As winter set it and the rocket stoves started burning regularly I thought about using them for baking bread … which I do regularly and I thought would be great if I could do without having to use the electric oven. The stoves can be used for cooking but it takes them a long time to bring a medium/large pot to a boil … so I’ve only used them for a bit of partial cooking.

I remembered coming across (I think in the original Rocket Mass Heaters book by Ianto Evans) a kind of aluminum-foil dome that you could put on top of the barrel and use that as an oven. I was doubtful but decided to try making one. I thought about how to go about doing it for many weeks and came up with an approach that seemed feasible.

I built up a wire-frame that was designed to create two layers of aluminum foil (inner and outer) with insulation in between them. I used the commonly available in the village fencing wire … it wasn’t as thick or rigid as I would have liked it to be so I two twisted strands to get it to be more structural.

In these images you can see the continuous foil sheets, the inner layer already creating the dome and the rock-wool insulation going on. It wasn’t precision work … and it took much longer than I thought it would … I think I played around with it for almost an entire day.

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I ended up with something pretty fragile, funny looking … and honestly … discouraging.

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The structure wasn’t precise or solid enough to create a good seal with the top of the barrel … I didn’t think it could hold a temperature that could bake bread … and I just set it aside.

It took a few weeks until I decided to cook on the stove and to cover the pot with the aluminum cap. WOW … the pot came to a boil very quickly. I was surprised. I decided to give baking a chance … and boy did it work. The first couple of times I burned the bread a bit. I also ruined one of the silicon baking trays (and weakened the other one) because I placed them directly on the barrel top … and it apparently reaches a temperature much higher than what the silicon is designed to handle. I now place two flat (half) fire bricks on top of the barrel and the baking trays on top of them.

I now do a lot of cooking on the rocket stove. It takes some planning in terms of timing … for the cooking to coincide with the burning of the stoves. But with a bit more attention and intention a lot of the cooking is now done on the rockets. Pizzas are also now made on the rocket … much faster … tastier … and no electricity needed:

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Mamaliga goes on the rocket in small clay pots (that hold personal servings). Melted cheese on bread goes on … and more and more. There is a journey of discovery … what should be put directly on the surface, when to use bricks, etc … but the electric oven has been used very little in recent months. The gas cooker is also working much less. It is satisfying to be able to harness that is already there (and would otherwise rise to the ceiling) instead of expending (and paying for) more energy.

It works based on radiated energy. The aluminum foil reflects radiated heat back down onto whatever is cooking under it. It also locks in some convective heat (hot air rising) … I don’t know which is the more significant source of energy … I suspect the radiated.

One “problem” with the aluminum cap is where to put it when it isn’t used. Then a few days ago I had a thought … if the aluminum reflects radiated heat then couldn’t it reflect that heat back into the room. I went to the workshop and came back with a scrap copper pipe and used it to prop up the aluminum cap so that it reflects heat towards the couches in the room:

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… and that works too … really well … a very noticeable effect when you are sitting in the beam of heat that comes from the dome. I still need to bring in the copper pipe cutter to cut it down to size so that it can be supported with the edge of the barrel instead of projecting all the way down to the cob indentation … but it works.

What started out as a disappointment has turned out to be a really useful winter tool and upgrade for the rocket stoves 🙂

 

Split wood with a tire

I saw this video probably a couple of years ago. This year I ordered a new batch of wood and decided to give it a try … and all I can say is WOW! It doesn’t always go smoothly (depends on the size of the wood and tire, knots in the wood, etc.) … but it is always an improvement on hacking in the open. It is especially useful when cutting wood for rocket-stove size … generally smaller pieces than wasteful metal boxes.

The Second First Rocket Stove

It was on my mind for many months … rebuilding the first rocket stove. It worked good – though not great. There were some design errors and compromises and during the last winter there were more smokeback events that I could not explain. I wasn’t keen on taking apart something that (kinda) worked and embarking on another build project. So I played around with it in my mind for a long time. Eventually I had a design I felt comfortable pursuing, I did a simple cob test to confirm the materials I had … counted and purchased bricks … and decided to go for it.

At the last minute I decided to give it a chance to become a workshop build and so I published an invitation and sent out word to people I knew and thought may know other people who would be interested … this was 3 or 4 days before the planned weekend build … and once person did sign up … making him the first participant in the first workshop I have ever offered at Bhudeva. I had two pairs of helping hands – Annelieke and Horatiu.

The project was born when I did created this layout:

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I was able to take real measurements, finalize brick counts … and get confident enough about my vision to move forward. The first thing we had to do was to take apart the existing stove … which was magical … the knowledge that most of the materials can be reused … that the rest are non-toxic and can simply be tossed out anywhere on the land where they will be reassimilated by nature … its one thing to know this and another to experience it:

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I was surprised to find the metal heat riser mostly in tact … though it was dry and chipping. Most of the clay-perlite insulation was used in thew new build …  which … began by recreating the layout in place to find the exact position it would be in relation to the existing chimney.

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With the position fixed we were able to get to work on building a raised floor:

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And then, layer by layer, building up the core of the stove:

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… and when we brought in the barrel for a first fitting it started to feel like it just might become a real life rocket stove:

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In the following image you can see the experimental part of this build. I discovered these honeycomb bricks and decided to use them to easily create heat channels and storage mass. There are two air passages (barely visible in the image) that allow the hot gasses to flow from the barrel into the two-brick chamber on the left hand side of the image – where they flow up. Then (as can be seen in later images) there is a top chamber that allows the gasses to flow across and down the two-brick chamber at the top of the image (right up against the wall) – where they flow down and then out through the chimney. There were three experiment going on: 1) using honeycomb bricks; 2) introducing a vertical flow both with both bottom-up and then top-down flows; 3) and gaining improved heat storage by having mass outside (the shell of the bricks) and inside (the honeycomb pattern).

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This is as far as we got in the two days of work we had available. Horatiu and I agreed that he would come back for another day of work during which we will complete the build and fire it up for the first time. So during the next few days Annelieke and I continued doing some preparatory tasks. The most prominent task was the heat riser. Annelieke started doing a perfect and wrong job. Can you guess what is wrong in this image:

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Annelieke is doing fantastic work getting the bricks aligned and leveled … but she is laying them without overlaps … creating a beautifully symmetric and unstable structure. This is something I take so much for granted that I did not spot until a few more layers were built and it became very prominent. So It had to be taken down and rebuilt properly:

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While she did that I built some insulation chambers around the core (to extend the insulation that would be placed around the heat riser) and started filling them with the clay-perlite mix from the old core … and as you can see in the bottom-left corner I started playing around with cob … hoping for a better experience (I’ve had very poor experiences in the past):

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On the day Horatiu came back we finished building up the honeycomb brick chambers and the top chamber in which gasses could pass from the up-flow chamber to the down-flow chamber:

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The top chamber was closed with bricks and we then added on the sheet-metal container for the insulation:

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… filled it up with clay-perlite insulation:

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… and sealed it:

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… and suddenly that was it … everything was ready for a barrel:

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… and lighting a fire … the smoothest lighting of a new rocket stove I’ve ever experienced … excellent draft (probably helped by the fact that the core had a few good days to dry):

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I was then left on my own to slowly transport cob-worthy material, to mix it up in reasonable one-person batches … and slowly build it and transform the stove from something very mechanical and engineered to something organic and mysterious:

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There were a few places where seeds apparently got into the cob mix … and given that there was a lot of moisture inside this happened, in a few places:

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It now, though still slowly drying, looks like this:

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The second lighting of the stove, in contrast to the first, went very poorly. I am guessing it had to do with the loads of cool moist cob. This is where the experimental part may have also kicked in … the gasses may have had a hard time establishing a complete and continuous flow throughout the stove, resulting in serious backsmoke. During the third lighting I was careful to preheat at both cleanouts, to start very gradually and only when the stove was flowing well to put in a full load … and … to my great relief … it ran perfectly again. The fourth lighting was not so good … I wasn’t as patient. Since then I’ve lit it a few more times and it has been going fine.

I estimate that, aside from the bricks, I put on over half a ton (maybe up to three quarters) of cob. Thats a lot of moisture. At the end of the first lighting (before cob went on) when the full load finished burning the bricks at the back were noticeable warm. Not so during the next few lightings. There are many liters of water in there that need to dry. This is something that should be taken into consideration in a construction schedule. I started the construction early so there would be time to experiment and make corrections. I did not take into considerations how long this would take to dry … it still is drying.

Cob was much more friendly this time … finally. I played around with different finishing techniques … I still am. It is a subtle thing finishing and there seem to be numerous paths to go about it. It is very pleasant work (when it works) to be able to mold shapes, smooth corners, add colors. It felt like a complementary and balancing process to the more structured, measured, aligned process of building the core. It felt free, open, secure,  … embracing and welcoming. It is a pleasant way to finish a build and a much more pleasant result 🙂

The stove has already worked for a few cold nights. It’s still hard to say how good it works because: its not that cold yet, there is still humidity in the mass, the barrel itself is partly wrapped in cob … so a few things still shifting and changing. I am looking forward to experiencing how it works … both the immediate heating and the heat storage for the night. I have a feeling that it is going to be more efficient in terms of wood consumption (then its predecessor) … I am curious how it will compare in terms of heat storage (the previous stove was all storage, slow to heat up but then radiated plenty of warmth throughout the night – sometimes even overheating the room).

Village Video DVD: How to Build Rocket Mass Heaters with Ernie and Erica

When I started playing with rocket stoves the main resource available was the Rocket Stove book. Though I still consider it a must read for anyone heading into Rocket Stove territory, I do not consider it sufficient. It left me with many questions, it has some outdated information and some things that, knowing what I know now, are borderline wrong. Fortunately there is now an additional resource that complements it wonderfully.

Earlier this year we participated in two kickstarter documentation projects on Rocket Stoves. I’ll speak shortly about one and at more length about the other. The shortly: the Paul Wheaton 4 DVD pack is a nice to have thing. It was a huge success on kickstarter which made its production value all the more disappointing. It includes 4 DVD’s none of which felt complete and comprehensive (the Fire Science came close). It has low quality video and audio. It was nice to have a glimpse into a workshop with Erica and Ernie which I do not have access to … but it was an opportunistic production. With the funds it raised I felt there was an opportunity to create something much better … an opportunity that was missed. This kickstarter project felt incomplete and … well … icky.

Which brings me to the second production How to Build Rocket Mass Heaters with Ernie and Erica by Calen Kennett of Village Video. This was the first of the Kickstarter projects to launch and though it got fully funded it did not create the buzz that the second project got. It was delivered late (I just received mine a couple of days ago) but that was because loads of caring production work went into it.

It documents an entire build of one Rocket Mass Heater (the one you see on the cover) – an 8 inch system built over an existing wooden floor. It covers very many details which appeared as questions during my two builds and I have not seen addressed anywhere else, covering tools, materials, design, build and finishing. It has excellent quality video and audio. It is a composite of footage shot on site during the build together with a separetely shot and well thought out interview with Erica and Ernie (with excellent quality audio). Inside the DVD case there is a printed page with a list of tools and materials used in the build … superb attention to detail.

The kickstarter edition included Erica and Ernie’s recently published The Art of Fire (which I have yet to take in). In addition there was a surprise on the Kickstarter DVD – the detailed plans for the RMH in the DVD (which more than makes up for one thing that I believe is not emphasized enough in the DVD – an explanation of the basic structure of feed tube, burn channel and heat riser and their dimensions). It is a production infused with care and quality.

If you want to get started with Rocket Mass Heaters I would recomment the (above mentioned) book and this DVD.