Skandi Rogers wrote:What is the heating at the moment? I would think the quickest way to guess how many kW you need is to see how many you are using at the moment. For example we have a 30kW output pellet boiler that runs around 30% most of the time so our house takes 10kW to heat with the outside at 0 and the inside at 20 using a mix of radiators and underfloor heating. However to heat the house downstairs (175m) from cold takes all 30kW for 4-5 hours. we have poor insulation and a lot of heat loss from badly insulated pipes between the boiler and house, but also have south facing windows which help a lot, IF the sun shines Your heating needs to be sized for the worst case so after a week of overcast weather at -6. my fear with a 5kw system is that from cold which it will be every time you let the fire go out for more than a day it's going to take you 6-7 hours to reheat the air and even longer to reheat the mass.
The official way to calculate is very complicated you need to know the R value of all walls roofs and windows which in practice is impossible to find on an old house especially if it's been retrofitted with insulation. I can find estimates online especially if you look at air to air heat pumps they estimate that a new/well insulated house requires 55w per m3 so guessing your house is 2.5m tall inside you would need 13kW to heat it.
heating has been wood stoves so far, but its been out of use for almost ten years so i've no data to go by. i'm guessing people were simply very cold-tolerant. :-D what i'm getting from you is that 5kw might be marginal and i tend to have the same feeling. especially since the oven is meant to server various purposes. i'm looking at the B28 batchbox from uzume at the moment, which gives more than 8kw from two firings.
what would the disadvantegs of a bigger system be? i'm struggling to see it, other than size and space isnt an issue in our case. bigger simply means i have to fire it less often right?
how does the theory work in terms of how much mass is ideal? is it a simple trade off of direct heat vs stored heat? in other words, what speaks against adding more and more mass, other than the obvious fact it takes longer for the heat to dissipate into the living areas.
and whats the general knowledge on convection heat (hypocaust) vs radiation heat (like hot water panels in the walls)? i'm assuimg in a well insulated house, it makes little difference. what about older badly insulated houses, is it generally a bad idea to convection heat such a house, i.e. wasteful and expensive? in my case the convection heat would go to the top floor, newly built and well insulated rooms. or is it likely more efficient and cheaper to install wall heating via hot water and radiate the heat.
been into rmh for a while and have a little experience with cob ovens. however thats not much good to me with this project as its quite ambitious. i'm looking to heat around 100m2 in this house via a central batchbox mass oven, with warm air ventilation to the rooms plus a small copper tubing hot water system for underfloor heating of a very small, but important space - the kitchen.
the oven will be located where the old roof meets the new flat roof and i'm guessing its gonna require some power. the house has been insulated recently but part of the floor will remain uninsulated, at least for the medium term, so there is heat loss to consider, but not from the roofs or the room where the oven will. still the oven needs to:
- radiant heat the room its in, very high 65m3 room
- warm air vent 3 rooms, ca. 100m3
- hot water underfloor heat a 25m3 room
winter lows are -6 at max. with many sun hours, and the south facing windows collect considerable amount of warmth which is stored in a 2 inch thick cob wall on the northern side. i have a bunch of very capable builders with me, so i'm hoping to save on costs by doing the construction myself.
one general question i have is how do oven builders calculate the required power output for a certain amount of m3 space?
well, the options i'm seeing right now are:
seem to do great work. obvious advantage is the black baking oven. but i have doubts over the power output being enough? they dont offer a copper tubed hot water system, so the question would be how tricky it would be a add that myself, or have someone add it. also if i chose this, would i be well advised to sacrifice the bench in order to give more power to the other functions?
sent me info on their modell BrulR 1.5 which is a rocket batch box side winder with heatriser, diameter 150mm. 5KW and 93% efficiency. he offers an integrated copper tubed hot water system for underfloor heating in 3 sizes, of which i'm assuming the smallest would suffice. only disadvantages are the lack of a baking oven and a bench.
Hire someone else to make a design:
well, seeing as there will be some level of adaptation / individual design i'm gonna be paying some to help creat plans anyway. what would your advice be? and what options am i missing? what considerations am i missing?
how do you guys, in europe, see the development of governmental regulations on wood stoves? dont really feel like building an amazing 5 grand oven thatll be forced out of order in 10years. or would that be an argument for a prefabricated oven with very good exhaust specifications?
thank you all for your great work - more power to you!
i've built a rmh and a double chamber cob oven before but i'm no expert.
for a major renovation of our house we are planning on building a large central rmh/wood oven to heat a small two storey house. we're looking at options of including underfloor heating/hot water and/or pizza oven in the plans. so yes.. its quite ambitious. the underfloor heating and hot water (for feeding wall heating panels is priority. so i need advice and am happy to pay for it (or make you a website!
anybody know of rmh builders/consultants or oven builders with some experience in rmh in central europe, so france/germany/netherlands/switzerland?
i'm looking at buying/renting sth like 2 acres of grazing land to keep sheep and plant some fruit trees.
is there a "beginners guide" book or thread you could recommend? can someone give me some base data like.. how roundabout how many sheep make sense per acre, races of sheep (primarily for meat and ease of keep).
anybody living in france know about beaurocratic requirements and costs involved?
Thank you loads for your reply, it's great to get the assertion from you guys directly! Highly appreciated and I would love to join one of your workshops if it wasn't for the distance < maybe there will be one in Europe one day.
So we went ahead and built the oven with 1 inch of thermal Mass and unfortunately as it was my first time building something like this I made all the mistakes you can imagine. The most crucial one being that I didn't get the mixture right for the thermal mass, It was too wet and therefore kept slumping and the whole thing just didn't go very well. I decided to mark it down as experience and make another oven and given the second opportunity I decided I will try to build a slightly lower oven to favour Pizzas. This time the mixture felt really good and the build went very well. The ratio of sand to clay was about 4/1 and as it dried out there were no cracks and the thermal mass dome looked Great so I was quite confident. As my daughter's birthday came up I thought I can use the oven the way is and add the rest of the installation later. Sadly now after three firings the thermal lining has developed a lot of fine cracks and even one larger one which is about a 10th of an inch. Is it possible that I fired the oven too hot? I am a bit surprised since all the tests of the mix went well and there were no cracks whatsoever after completely drying the thermal lining. The insulation had not dried out completely before firing so could that have caused the cracking? the inner lining however worked great in terms of efficiency. We got the oven to 350 Celsius in under an hour , baked 4 great pizzas and even with the thin installation we have at the moment we had no problem baking one round of breads afterwards. After that the oven still measured 130° Celsius
Would there be at any point in trying to remove the installation layer and patch the thermal lining from both sides or is this oven going to have to come down?
Obviously very disappointed but thanks again for all your help and advice!
We have a beautiful Black Mulberry tree and harvest time is coming up soon and we have tried out various ways of harvesting the berries in the last couple of years. I was wondering what kind of setups you people have come up with to harvest the gorgeous but fragile fruits. Our best solution so far have been 2 huge elastic bedsheets elevated by four sticks each in the ground, it reduces the falling height and softens the land and it keeps the berries off the ground. Another bonus is you can let them ripen and Fall in their own time.
I will try and think of making a photo of our setup
I have never been much of a reader, but after the arrival of my daughter I have been given presents of 2 parenting books which I both really enjoyed in terms of the insights into the world that children live in and of course it is just worth it for the good advise you pick up here and there.
Anyone have some favourite parenting books they can recommend? we like Montessori for example
I have built an outside earthen oven, as in the double chamber oven, And Im contemplating various ways of protecting it from the weather. One idea I liked was to simply cover it rather than build a roof which takes up quite some space. However, The main argument against doubts is that's it simply isn't pretty to look at a plastic sheet all year round rather than the beautiful oven you built.
I would be prepared to use proper roof tiles but I don't want to build a structure that can support them. That would mean a lot of foundation work and equally take up a lot of space. I am looking for a solution that is lighter, Like sheet metal . I don't like tar paper.
Can anybody imagine a type of roofing, possibly even involving some natural materials (as in unprocessed). Obviously it needs to be water repelling, Strong enough to withstand strong rain, if possible not too susceptible to Wind and not easily flammable, However the roof Will be quite high and further precautionary steps would be possible to make something heat resistant. The only obvious types of natural roofing I can think of is Thatching, Which obviously is not to suitable over an oven.
Hi guys, a couple of questions as we are going to build this oven soon, according tothe plans.
1 Considering the re-burn going into the exhaust pipe, does the pipe need to be stainless steel or will a copper pipe stand the heat?
2 I would like to tune the oven to heat up faster and cool down faster so it suits our small family needs better. To bake about two pizzas and one bread Will take about an hour and a half of baking time or a little less. Do you think an inch of thermal mass should be about right for that or will I risk it's cooling down too fast? I have obtained Chamotte Stones an inch thick for the base to go with it. Also what would you recommend as maximum installation thickness for such a setup?
3 in the book you mention that the exterior may not be treated in a way that the oven cannot breathe. How does simply linseed oiling it fair in that respect? Does that also inhibit breathability? And does polishing the exterior clay make a difference?
Hi Satamax, Thanks a lot!
I had already downloaded your file but not installed the suitable viewer for yet. Just looked at it and looks like a great design, I will certainly incorporate or maybe base my design on that. I suppose you would add a deflector on the inside of the feed tube, like two or three fire breaks. also I am contemplating and oval shape.
Would you just brick the dome? I am not sure my skills would it be good enough to do that. Maybe an inner lining fire cob followed by an inch of cement for Weight bearing structure and then insulated cob around that? That would raise the question of whether cement gases could enter?
So there have been some changes made to the plans, it contains some definite errors.
First of all I am going to use the wet sand method rather than the oil drum for the shape simply because when the oven is heated up the metal expands and I presume Will simply bust the cob around it. Essentially the shape and build will be based on wisners double chamber oven. I am however still interested in keeping the Rocket as designed in the pictures above to draw the flames right across the top of the bake goods in the way the uni does it.
The next question would be whether the cob is structurally capable of supporting its own weight in a much shallower Dome. How much lower do you think I can make the dome than in the original design? Of course with out changing the base dimentions
it's been about three months now that I have been doing some occasional research on different types of pizza ovens. At this point I can safely say I have read just about every Fred I could find in this forum along with many of the great sides that people have linked to and of course watched tons of YouTube videos.
Because there are so many different ways of building is, the most important stage was defining what exactly I want.
Overview of my aspirations for the oven:
-decently higher temperatures from above and below to make excellent pizza 400°C would be ideal
-Heat retaining qualities to last me at least one round of the baking bread, circa one hour of 200°C
-Because I won't be having many parties catering for 50 people, I don't want to spend hours preheating the oven, maybe 45 minutes would be good. This is also a factor in fuel consumption, I'd like to be able to make a few pizzas and two breads without using tons of wood.
-I don't have welding experience although I could find a friend if necessary, But prefer without.
-I would like to reuse A large 200 L oil drum that I have for the shape and I am hoping to build primarily from cob, Stone and tile debris and rubble and get away with only having to buy the firebricks and some small things if necessary. i have a small amount of cement here aswell.
wisners double chamber:
i have studied the wisners double chamber cob oven in detail and for my purpose it might take too long to heat up and is more suited for frequent use. however it is on my list of possible solutions. they mention the possibility of reducing the outer shell for faster heating but thats coming down from an original 2h heat up time.
traditional pizza oven:
i have studied traditional ovens and their dimensions, which again is fantastic but takes long to heat and is not taking advantage of rocket/reduced fuel possibility.
hybrid rocket cob oven:
then there are the hybrid rocket cob ovens that often have the riser come up right at the center of the hearth, where it seems to me that of the hearth gets too hot, its too cool at the top and the hearth often doesnt withstand the brutal direct heat. they also seem like one of the more challenging builds.
fancy new tech portable pizza ovens like uni 3:
https://youtu.be/YyR5Hbi2iig using part of the rocket principle to draft the flame along the top of the oven and over the pizza and the stone, resulting in high temps above and below in short heat up. downside: unsuited for baking, expensive and my garden doesnt grow pellets.
i'm wishing that you guys, who i can see have vast knowledge and experience with rockets might give me feedback on my plans. my idea is to use a rocket for fuel efficiency as a hybrid or the uni do, but combine it with a not too deep cob insulation to give me the ability to bake. i'm adding a chimney at the front like ernie and the uni to draw smoke out the top and am considering (not sketched) a 2nd bake door like ernies. the deflectors are an idea that came again from uni and from a sketch by satamac.
1 what do you think i can use to line the inside of the drum and even lower the height on the inside with. clearly it needs to be lowered for the design to work. the difficulty there is sctructural, so it doesnt just collapse. could cob work and how could i maybe suspend it?
2 what can i use a binding slur in the base together with rubble, stone, tile and glass debri? cob slurry, cement or a mix?
3 the heat riser will not be insulated with sawdust and ash as in the sketch. i read all about metal in heat risers and its obviously not the way to go for longevity and food safety, so i'm thinking on molding a cob riser or just fire bricking it up.
hugely appreciate your help and criticism, i'm just hoping to finally settle on a design and get started.
Hi guys, I have read many threads, as many as I could find in the forum on rocket stoves, cob ovens etc. I have also read the thread about the metal heat risers and I am glad I did. The question I couldn't quiet get a clear perspective on is how firebreak compares to cob in heat rises. I understand there are many different recipes for cob and qualities, But assuming a very good cob mixture, How do you Think it compares to firebrick regarding longevity and insulative qualities? On top of that I wonder, If used in a Black oven situation, Can you imagine a difference in odor and flavour coming from firebrick vs cob?
Hi Marian, I like what you wrote. We are in the process of finding a possibility very similar to what you have described. At the moment we are looking at pieces of land as well as visiting various community building meetings around France and Germany.
It would be very interesting and wonderful to have a chat together.
Thanks a lot for that explanation hans,– that Clarified a lot of things for me. I understand that sharp sand is something quite different from beach sand, Which is the one I have available here for free. Will beach sand clog and go dense? Or Wil lit do the job just not as well as sharp sand.
I have been researching a little bit about DIY recipes for seed starting mix and my impression is that almost everybody adds either perlite, vermiculite or coco fibre for structure, aeration and water retention. I presume this is because regular garden soil will go dense and anaerobic over a couple of weeks. Is that correct first of all?
Or if not are there ways of amending my garden soil with things that are commonly found in Gardens as in things I don't need to go and buy, such as maybe saw dust? If I makes my screened composts with 50% sawdust, Will that work? Or is the sawdust maybe a platform for excessive fungal growth that is bad for the seeds?
And last question, is there any truth to the myth sterile seed mix? Four example are there specific types of seeds that require this, clearly it doesn't apply to a lots of seeds as I have never used sterile mix before. However there have been types of seeds that I have always had trouble with. Two examples I can think of our parsnips and parsley.
Nice to hear from you. I have just caught up with your project it looks like you're doing a fantastic job in a Beautiful area.
We are not fixed on a specific area but definitely South of Paris, anything a bit inland from the West Coast, Maybe perigord or also Brittany. The latter being interesting for us as Celtic musicians. However the main determining factor I presume Will be the landlord and the Mayor as we are hoping to buy cheap land off grid.
My wife and I are continuing the search for possible land for ourselves or more preferably for several parties. At the moment we are focusing our research on France, As it's our impression that building alternatives style housing, which is a top priority for us, might be less difficult of the developed countries in central Europe. At least there is knowledge of people having built and gotten permission for e g an earthship. Additionally it's not too densely populated, so the chances are reasonable. For European standards that is. However we are not opposed in any way to leaving Europe but it is the more realistic option in case we need to do it on our own.
Would anybody be interested in an online meeting of sorts? In order to consolidate and exchange ideas for creating communities in Europe. If common ground is found then it would be worth everyones while to start a small task force that assesses the viability of various scenarios.
We will also continue visiting Community Building workshops and meetings in order to increase our exposure to like minded people.
More generally speaking I would be very interested in other peoples ideas regarding the best way of exchanging knowledge and information which we are all individually gathering with our efforts. There must be a way to connect some dots and create increased value for everyone. One possible idea that has crossed my mind is of course blogging about the search for community.
I came across this thread after searching the forum for Community/ Land acquisition/ large scale living projects. its Especially interesting to see because this thread is particularly about Europe which is where my family and I are based. My wife, Our daughter and I have you been researching and planning a move to either an existing eco-village type of settlement or alternatively start our own. Of course the first option is always preferable. In our case it hinges on the ability of building housing in alternative ways which is particularly difficult in central Europe due to building codes etc.
We have also travelled around Europe doing various workaways in order to meet people and find out about local building codes and land prices. Currently our top spots include
Brittany in the north west of France (vast lands at low price, Mild gulf stream climate and it's known for quirky mayors and eco-friendly people ),
Greece which is particularly interesting for its current intellectual state, Having Learned the hard way that capitalism is not the future , there are many young people willing and very able to go into new alternative ways of living pus low Land prices. The main drawback being, Probably more difficult to aquire tools and means in lack of healthy craft and manufacturing structure.
South Eastern Italy, spectacular landscape Beautiful weather fantastic people but unfortunately not a whole lot of land available in large sizes, Although the prices can be quite reasonable also. Would probably intend to seek out a mountainous area for fresh air and water in the summer, no further knowledge on building codes
I am stunned by the price of the land in Slovenia that you posted. It would be very interesting to find out more about the political situation and the restrictiveness of building codes.
What I am Particularly interested in would be collectively creating A comprehensive List of these type of projects and settlements. Of course there is http://sites.ecovillage.org but I have the impression that a lot of new projects are not listed here and I cant seem to find any other list. One of the top projects in terms of organisation and holistic integration of living, organic farming, agritourism, alternative lifestyle and building, Business and Financial equity and what I also like a lack of doctrine is terraperma.ca . This is what we need in Europe.
I really look forward to hearing from you and continuing our engagement!!!