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 …Ā 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 chamberĀ (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 withĀ 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.
It’s time to try a next step – we are going to rebuild the one inĀ 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).Ā 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:
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.
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).
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).
We eat mostly vegetables and fruits, with some dairy productions and eggs. Most of it locally (in the village) produced.
We intend to be doing everything together: working, cooking, cleaning. We’ll see how this flows.
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).
When it comes to cold (moist and frozen) climates like ours here in Romania, there are quite a few things that felt, to me, incomplete, missing or even wrong in Earthship design (including the latest and greatest Global Model). To me what was missing most is the lack of explanations of how things work and why they are designed the way they are. I could not find satisfying answers in any of Michael Reynolds’ Earthship books (Earthships have evolved way beyond their description in the original Earthship books) nor online in many of the documented builds and open discussions about Earthships.
Then a few days ago I published this post about ventilation problems in an Earthship and began to compose my thoughts for a follow-up post. The solution seemed to come in the form of earth-tubes. The first resources I came across (pretty much as they were presented in the search results) were:
Ā Wikipedia – which provided basic technical information.
The Natural Home – which provided a convincing argument for earth tubes.
BuildItSolar – which raised some questions and left me with some doubts.
Luckily I stubbornly pressed through a few more pages of superficial search results and on the 3rd or 4th page found an article by John Hait inaptly titled Umbrella Home. The article blew me away. I ordered the book and couldn’t put it down – I read it word for word in just over a day and will be re-reading many parts of it again.
The book truly lives up to its subtitle “improving the design of earth shelters”. Not only does it open a door to a much deeper understanding of earth-tubes but to do so it introduces a fantastic concept of a large insulating/blanket which surrounds an earth-sheltered house in which earth-tubes can really come to life.
The core idea (backed up by accessible explanations and practical research) is to create an insulated and water-proof blanket that encompasses the house and a large area (~6 meters) around it (which can be achieved with more or less the same amount of insulation materials used for standard wall insulation).
This insulated umbrella creates a large body of earth which is dry and functions as a huge thermal battery attached to the house. The house itself acts as a solar collector to slowly charge the immense thermal battery during summer. Then, during winter that battery slowly discharges heat back into the house.
Earth tubes are used with this umbrella (in a way that could not achieved without the umbrella) to passively generate both ventilation and temperature regulation (cooling & warming) of the house. Because the earth-tubes run through the thermal battery surrounding the house they work as a super-efficient heat exchange system. A passive air-conditioning AND heat-exchange system that is simple and affordable.
Ā
As a cherry on top Ā – imagine running an uninsulated water supply pipe under the umbrella and having water preheated to 21 degress (celsius) during winter Ā (cold water supply has to be insulated under the umbrella). As someone who washes dishes with freezing-cold water (unless I fire up the wood boiler) I am watering at the mouth at the thought of washing dishes with passively heated (no additional energy expense or effort) warm water. Not to mention energy savings in heating bathing water.
This may cause a problem with Earthships that include rain-water harvesting stored in buried cisterns. The cisterns, if buried close to the house, under the umbrella will become a source of warm water. Cold water would have to be cooled somehow and I don’t know what effects this may have on the stored water. Since we’ve decided to forgo rainwater harvesting and put in a green-roof this is not a problem for us.
If you’ve already built an Earthship in a cold climate and it isn’t functioning as well as you thought it would I believe that at least some of the measures described in the book can be added to your Earthship to make it a much better home.
I don’t recommend trying to implement this from the basic information in the article. I STRONGLY recommend reading the book word for word. It is educating and empowering and fun to read.
I am now (again) heading back to the drawing board to revisit and rethink our house design. I feel I know better now and I am grateful to John Hait for his work and for making it available to others.
If you are reading this and interested in the technical aspect of Rocket stoves you may want to scroll down to the last part of the post where there is a description of what we actually built. But first, I do will indulge in some personal reflection about rocket stoves.
What is a Rocket Stove?
If you’ve never heard about rocket stoves, though I’ve mentioned them before, this short video is the place to start. This video drew me out of the theoretical reading and into action – anyone can experience the wonder of rocket stoves by recreating what is demonstrated in it:
A rocket stove mass heater is a more elaborate stove built around this concept … it is simple to build, efficiently burns wood – the rocket partĀ (more then most existing stoves) and equally effectively stores and radiates the generated heat – the mass part.
Learn to build one with the one and only rocket stove book
Visit the rocket stove forum (lots of hands on information and helpful people)
Of course you can and should search the Internet and find plenty of information about them.
However if you want to build one I strongly suggest you get the book – there are a few core details that you have to get right – once you get those down you can play around with it a lot. Though there is plenty of freely available information you will be hard-pressed to find all these core details without the book – at least that’s been my experience.
On to our personal rocket story
A Screeching Halt
Last year, as we were in the process of purchasing the land we currently live on, we were also working closely with our friend and architect on designing our hemp-built house (much more on that in coming posts). He designed a beautiful (and functional!) house, but the more beautiful it got to be the more I began to question its economic feasibility = I didn’t think we would be able to afford to build it. We were really committed to the process and invested much effort and resources in pursuing it (including a visit I have yet to write about to the UK to consult with an architect experienced in hemp construction).
As we were working on our rocket stove it was Andreea who insightfully recognized the point at which our beautiful house came to a screeching halt. We were doing some financial planning and were inquiring with our architect for some input on the house systems. We were sitting in his office discussing options for a house heating system – seeking a rough budget to plug into our calculations (which were already looking grim). He picked up his phone and called a fellow engineer. The conversation resulted in a mind-blowing figure ouf 15,000 euro (half of our target construction budget). We realized that something was not right – we felt that the architect and the engineer lost touch with us and our wishes. Further inquiry into the subject brought the figures down to 7,000 euro – still a lot of money and out of our budget.
Though the project continued to move forward and is still alive though dormant today, from that point on it was winding down. Our wish to have a comfortable and warm home, it seemed, could not be fulfilled within the budget we had.
Preparing for Winter
By the time we moved out it became painfully (at the time) clear that we would not be building a new house this year and that we would probably be spending a few years in the existing traditional Romanian village (cob) house. So, we began a long and ongoing (though definitely coming to a first end) effort to fix it up.
The house has a small hall, a small pantry (we converted into a bathroom) and two rooms. One room has a traditional Romanian wood-stove (the other had nothing). We had lots of plans to do lots of things. Though we did lots of the things, many were not in the plans and most of the plans did not reach execution. Our plans did not include building a rocket stove this year. They did include buying a second stove and a third wood-burning boiler.
Then, we discovered the (above mentioned) 16 brick video, we purchased some firebricks and tried it out … and it worked fantastically. We used it quite a lot for cooking outside.
At one point, just for the fun of it, I even built up around it and simulated a rough rocket stove . I used the parts of an old wood-boiler for the heat riser:
Seeing the horizontal burn for the first time was a magical experience:
And then when I placed a barrel on top, it got really warm really fast:
Then came the two+ weeks of non-stop cooking during which we made loads of winter preservations. We were practically living next to the small rocket stove outside. Then when we moved indoors in the evenings to escape the cold and complete the jar preservations we would light the wood stove. It was painful to see how much wood this stove consumed (and continues to consume) compared to the 16 brick rocket stove outside. Everyday I would have words of awe about the outside rocket stove and complain about the wood-greedy stove inside.
Slowly I gathered the courage to suggest weĀ try building a rocket stove instead of buying another wood-guzzling metal stove. And so it began … from here on it’s going to get a bit technical.
Constraints
There were a few constraints shaping this project for us:
Timing – we had already finished putting in wooden floors including a corner of ceramic tiles in each room to house a stove. We did not feel inclined into removing parts of the floor to install a cob-bench (the mass part of the rocket where heat is stored) and we were not keen into working with cob as it takes time and experimentation … and we already had quite a bit on our plate. So we were going to build a stove without thermal mass … making it’s heating efficiency questionable.
Barrel – This is going to be a recurring theme here at Bhudeva – but finding used/2nd hand anything is much more difficult here in Romania then in the USA, UK or other western countries. This is especially true in villages where everything is used, reused and used again, often beyond the point of efficiency or even safety. A key element in the rocket stove is a metal barrel – and for many weeks (which delayed the project) we couldn’t find one. We finally decided to build a rocket stove with “firebrick chamber with a top metal plate” instead of a barrel (we have since found and purchased one used barrel and have a few more lined up … we will keep them stored for future needs).
Insulation We also could not locate (at reasonable prices) any of the suggested insulation materials for the internal combustion chamber – we ended up using wood-ashes – they may not offer the same level of insulation and they may settle over time but this is what we had available to us.
Size – the actual stove – where all the burning takes place is a systemically and purposefully twisted path which, from a certain point early in the path (the horizontal burn chamber) must not become narrower. This is to prevent smoke and dangerous gases from returning into the room – the stove generates a powerful draft and nothing must impeded that flow. The traditional Romanian stove configuration is for a 12cm chimney flue – which is also the size of the chimneys usually built into the walls. Since we did not want to make a new opening in the wall for a chimney we had to adapt to that limitation. This is when rocket stoves designs are suggested for either 15 cm (6 inch) or 20 cm (8 inch). This meant a smaller scale and tighter design and indeed everything was scaled down accordingly. However, in retrospect, given that we built a spacious “brick barrel” as thermal mass – which slows the flow of gases before they exit, I believe we could have gone with a larger dimension in the stove with the limited 12 cm exit flue.
Model First
Like most of the good recommendations in the book, building a model of the stove is an important stage of work – and, as recommended, it should be done on a level surface (I tried to cut this corner and it was a waste of time). To that I would add that it should be built somewhere where you can (a) work on it over a period of time; (b) light it; (c) keep it out of the rain or other wet elements. I built our model in a corner of our barn which answered to all of these criteria – and luckily so because we went through quite a few iterations.
I actually used such images to document my progress of the layers (both as I built them up and took them apart) in building the actual stove in place. There were many small details and the images unburdened my memory and were very useful in actual construction. I spread construction sand on the floor to level it. This is Ā the first floor level model (it changed later in the process) … it is designed to raise the rocket off the floor and create ash collection both under the feed chamber (right) and at the exit flue (left).
On top of that came the “floor” of the rocket itself – intentionally adding more depth to the ash collection chambers.
Then of course the burn tunnel
… and off we go Ā – and you can already see the fire climbing up the feed chamber (the feed tunnel is not yet built up):
The model worked OK. The biggest problem, and one that carried over to the actual stove was the fire crawling up the sticks and out of the feed chamber. I now believe that the cause of this was that the feed-chamber and ash-clean-out beneath it Ā were not sealed properly. So the stove instead of sucking air down from the top of the feed chamber was now also sucking air up from below which both lowered the intensity ofĀ the down-draft AND provided an alternate up-draft.
Also, if you decide to build something not quite by the book be prepared to take risks – as not everything can be tested (simply) in the model:
Ā When I built the model I realized that I could not seal the brick chamber nor the top metal plate to the bricks. This meant that we could not assess how effective the generated heat would be contained and radiated from the stove.
Though the top metal plate (can be used for cooking) heated up rapidly it had a surprise for us in the actual stove. The heat generated by the rocket is so high that the metal (5mm thick) warps … the corners fold out creating stress on the cob that seals the plate to the brick structure beneath it. The cob has cracked numerous times (and let out poisonous gases) and we have had to reseal it (simply applying another coat of clay-slip)… it looks like we have reached the point where it is properly sealed – though only time will tell – we check it regularly.
Our Stove
The following images depict the actual stove in construction. First a simulation of the base layer to get its position in the corner. Next time I would try to leave more space between the rocket and the walls to make it easier to access and install the chimney parts – it was a struggle.
Then a little messier with the clay-sand mortar to keep things in place:
In the middle layer (top image) I installed a metal grail to support the feed chamber and let the ashes fall – I notched (with a grinder masonry disc) three parts of brick to support the grail itself:
Then a metal heat riser (used pipe cut to size at a metals shop in Cluj) went on:
and over that Ā went a piece of sheet-metal tied into a roll and then filled with wood ash
Starting to look like a rocket stove
Here the heat riser is sealed with the clay-sand mortar mix
Here you can see that the heat riser is positioned away from the center of the brick box. One reason is that I assumed that the brick-barrel would behave like a steel barrel does and that the wider space would heat up more/faster then the narrow space – so in this case the wide space facing into the room. The space from the other (left hand side) wall is determined by the location of the ash-pit and exit flue (in the dark area at bottom left of the image). Though I don’t know if this actual works – I preferred to have the gases “linger” in the box rather then get pushed out by making the space near the exit flue narrow.
The almost finished stove with a completed brick chamber (I decided to use refractory cement which has adhesive function for the brick chamber instead of the sand-clay mortar which has no adhesive function it simply keeps the bricks from moving and when fired solidifies into a brick-like material) and metal top still undecided feed chamber, a temporary chimney leading out the door and to the hall, a small pot of water heating up and Andreea checking something out (and providing you with some sense of scale).
We still had smoke-back and fire climbing up the feed chamber … which frustrated me greatly … until Andreea intervened with a bit of feminine surrender and wisdom and suggested we let go of the vertical feed and go with a front feed … which not only worked but demonstrated that the stove had excellent draft with absolutely no smoke-back. Here you can see a fully loaded feed with fire swirling into the stove and absolutely no smoke coming out:
Then Andreea took over the clay plastering. It failed miserable the first few times – the plaster cracked and fell of in chunks.
The third time she (1) added hemp fibers and some acrylic construction glue; (2) wet the bricks thoroughly before applying the plaster; (3) applied it in thin layers and worked it in thoroughly with a wet sponge; (4) continued to moisten and add clay slip as the stove was heated up gradually over the next two days.
The chimney winds through 3 corner bends (poor planning?) so it was a bitch to install … but we now have a great looking and working kind-of-rocket-stove in the bedroom.
Performance
Before I talk about the stoves heating performance I’d like to talk about it’s other values – at least those that are important to us.
Independence – with no past experience in stoves or any of the specific disciplines involved in creating this stove and with no access to people with past experience we managed to build this by ourselves. It can be built fairly quickly (it takes more time to gather materials then to actually build it).
Efficient and Ecological – when the stove is first fired up some smoke comes out the chimney … but once the heat riser gets hot (very hot) there is no smoke – the stove performs a full and clean burn of the wood. Not only does it fully utilize the energy embodied in the wood (every time you see smoke coming from a chimney imagine waster dollars – all of that is wasted energy) – but it is also ecological since it releases very little pollution (compared to most regular wood stoves). If you were to buy an industrially made central wood heating stove you would pay a heavy premium for “re-gasification” – which is essentially the burning of the gases release when the wood initially burns. With the rocket stove this is an inherent and simply to achieve function (the insulated heat riser gets too temperatures high enough to burn the gases).
Beautiful – you can shape and mold it and make it your own … which ends up uniquely individual and special.
Sustained warmth – the thermal mass (in our case the “brick barrel”) contains all of that efficiently generated heat and slowly releases it into the space instead of letting it escape out the chimney.
It works great. Though we purchased a lot of wood we did not have time or do enough to dry it properly. Fortunately we also have a huge pile of junk wood that we collected from all over the place – that wood, after we cut it to size, is very dry and perfect for the stove. In a regular stove it may be desirable for wood to burn “not too fast” because heat is present only when there are flames (once the flames go out the stove and usually the space, unless it is superbly insulated begin to cool). In a rocket stove it is best to have a fast and efficient burn – the heat is stored in the mass and then released. We are currently lighting it with a few batches of dry wood and then some of the partly dry wood in usually larger chunks of wood. If we were to use only dry wood the stove would probably get really hot (too hot to touch) in 2 or 3 hours. Ā As we are currently running it it takes 4 or 5 hours.
It uses much less wood then the regular wood stove (I can’t say how much as we are not yet setup for measuring and comparing. But more importantly it’s effect on the room is very different. Since we don’t have a radiant barrel (only the small top surface radiates heat immediately into the space) it takes time to warm the space – the other wood stove warms the space rather quickly. But once its warm the space will say warm much longer (again I don’t have measurements for comparison) … but we usually feed the stove one last time at around 10pm and at 7am the room is not cold (though not warm). Ā With the regular stove the room cools drastically in an hour or two – once the fire is out the room begins to cool!
The heat has a different quality in the rocket stove room – it’s hard to put in words. It is a softer, deeper and rounder warmth then the regular wood stove.
It can be used for cooking – doing so requires using either very dry wood (which burns fast and releases a lot of heat) or patience (it is generally slower heating then the wood stove where fire almost directly heats the pots.
Until recently we have had to deal with the metal warping problem. It strains the corners of the cob that join the metal plate to the brick box to the point that cracks appeared and smoke/gas escaped into the room. It has been easy to fix – adding a clay slip – but has required constant attention. Time will tell if this is going to be an ongoing issue or one that we have resolved.
I would have been happy to make it bigger (see above mentioned constraint 4) and to get the vertical feed working properly. But we didn’t have time … it as getting too cold in the room and we still had plenty of work to do to prepare for the winter. The result is a stove that needs to be fed every 20 or so minutes … but that is a small inconvenience we are happy to accommodate.
We are very happy with the stove. It came to life just as the room was becoming unbearably cold. Creating it was a hugely empowering experience. We are very much looking forward to experimenting with it more and eventually incorporating simple rocket stoves we can build and maintain with our hand instead of complicated systems that cost many thousands of euros and place us at the mercy of technicians and engineers and companies.
We had plans to build a second rocket with an integrated baking stove and a thermal mass bench (wood framed!) stove to replace the existing wood-stove, but time did not allow for it. Next year š
It’s been a frozen two days, it’s dark outside and cold is beginning to set – a good time to go and light the rocket so the bedroom will be nice and warm š
I first came across Rocket Stoves a couple of weeks ago at Paul Wheatons friendly website. I still do not grasp completely how they work but I am learning a lot (and asking a lot of questions) … in other words educating myself š
Gasification
Gasification is a word we’ve encountered many times in relation to high-efficiency wood-stoves. Here’s what I’ve been able to understand so far (excluding professional terms which I still have not got down).
When wood is burned some heat is (naturally) generated together with some gasses. These gasses still contain potential burning energy but in regular stoves they simple escape through the chimney. This is both a waste of potential heating energy and a source of pollution. Efficient stoves that include “gasification” create a kind of “second burning” by (1) containing the gasses in a secondary chamber and (2) by insulating the stove, containing the heat and increasing the temperature (the gasses require a higher temperature to burn). The result is much (drastically more) efficient burning and greatly reduced pollution.
The following video demonstrates the “rocket” burning result of gasification:
Thermal Mass
The Rocket Stoves depicted in Paul’s website is based around the idea of thermal mass – which is a fancy way of saying “something that can contain lots of heat it and slowly radiate it back into the space”. This can be a couch or a wall or even a water heater.
This idea of thermal mass is well known here in Romania. It is used in typical tera-cota village stoves where the heat is directed in a maze of passages that cause the stove to slowly heat up and then stay warm for a long time (a good stove can be lit in the evening and will still be warm the next morning).
At first I assumed that a thermal mass was an inherent part of the rocket stove. But that isn’t necessarily true. This next video demonstrates a rocket-stove used as a cooking stove:
More information and plans for this kind of rocket stove can be found here.
This application of the sameĀ rocket stove burning mechanism shows an insulated burner that is designed to keep the heat inside and direct it to a cooking pot. I think this can be a useful design for a cooking stove that can be used during the summer months because it doesn’t radiate unwanted heat into the space.
Water
One of the first ideas we played around with was using the same stoves for both heating the space and heating water. Though this can work it needs careful consideration. Though it’s tempting to think of the stove as heating the water, it’s useful to remember that as this happens the water also cools the stove!
If you add a water heating coil to a traditional Romanian tera-cotta wood stove it will heat the water, but the stove itself will cool down much faster and will have less effect on the space.
It’s empowering to slowly peel away the layers and connect with the common-sense behind heating systems. It makes me wonder about sophisticated technology vs. simple concepts. On the one hand gasification looks so simple to achieve and yet modern central wood-burning heaters, it seems, cannot achieve gasification without electricity!
We want to have a really pleasantly warm house when it gets cold outside. Building with hemp insures that we enjoy a wonderfully insulated home. Now we need to deal with heat – which includes both environmental heating and water heating.
In typically built houses which tend to be cold when it gets cold outside it’s more a brute force challenge. With an ecological house it is actually more complicated because it’s easy to design a system that overheats the house. We still don’t have a clear picture or understanding of our heating needs – though we are working at it.
In the meantime I wanted to share with you some great resources that we are using to educate ourselves:
Stoves Online (UK) – it s great resource for learning about the different elements that make up a heating system with a very rich offering of solutions if you happen to live in the UK.
Boiler Stoves (UK) – seems like a sister website which specifically explains how boiler stoves work and can be incorporated into a smart and efficient heating system.
Radiant Design Institute – though not an appealing website has a lot of really well-grounded and useful information I believe can be very useful especially to do-it-yourselfers.
IMPORTANT: this note was added after the post was published but seemed important enough to be inserted at the beginning of the post. I am just now realizing that my perception of heating requirements are based on experience of poorly insulated homes. This is why I expect stoves to be lit numerous times a day. But, in a properly insulated home the need for heating should eb drastically reduced. If this is true – then all our elaborate plans to use stove-heating may be irrelevant – since the stoves may not be lit long enough to generate hot water. Having a super-energy-efficient home may lead to us to simpler, existing ready-made solutions. We don’t know, and we don’t know yet someone who knows … so for the time being it’s all up in the air.
Some weeks ago we described an imaginary-heating system and since then we’ve come across numerous resources and refined our understanding a bit.
I think there are two core ideas that shape and guide our understanding and wishes of a heating system:
Most of the time we can shower when hot water is available – though it’s comfortable we don’t really need hot water to be available on demand.
Enough direct heat is generated by our wood-stoves to indirectly supply most if not all of our heating needs.
So what we can say about our envisioned heating system?
It will be an integrated water-based system – the same systems is used to generated running hot water and water for a radiant heat system.
The system relies as little as possible on electricity – we would like to have a warm house and hot water even during a complete power-out (though it may run better when powered with electricity).
The system will include an indoor cold-water container that will bring the water to room temperature.
The system will include a central hot-water tank (not a boiler!) that supplies both the radiant heat water and flowing hot water to facuets and showers.
The primary source of heat will be classic Romanian-village-style terracotta wood stoves. We expect to have one or two primary stoves in the living-space and kitchen. We both work from home a lot and cook a lot so these stoves will already be working.
We would like to design and build the wood stoves to include an efficient coiled water pipe that is connected to the radiant heat water circuit and feeds back into the central hot-water tank.
We would like to install a on-demand gas water heater on the running water hot-water circuit as a backup in case the water in the hot-water tank is not yet hot enough.
