Masonry Heaters, Stoves, Cooktops, Bakeovens

Discussion in 'Designing, building, making and powering your life' started by nchattaway, Jun 30, 2011.

  1. nchattaway

    nchattaway Junior Member

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    Hello all,

    We're trying to set up our property in the Adelaide Hills for an agrarian life where we can meet as many of our needs directly as possible. We have space for a good sustainable woodlot, plus my neighbours already have mature woodlots that they've made available until my own mature.
    So we want to use wood for heating, hot water and cooking. Initially I'd been looking at cast iron wood stoves like the "Aga" but they cost over $10,000 and what do you do in ten years if the firebox burns out? Even the 80s Vulcan Everhot, while much cheaper to purchase, would have this same longevity concern. Plus, they only provide heat when they're running and for a short time afterwards.

    I have The Complete Book of Self Sufficiency by John Seymour. In this book, there is a brief section describing the brick "all purpose" furnace he designed and built. It's light on detail, but this seemed more like something I could afford. After googling around, I discovered masonry heaters, including such things as Finnish contra-flow designs, which are optimised for efficient wood fired production of radiant heat in a dwelling.
    Aha! There are quite a few commercial producers of these heaters in the US, including the Maine Wood Heater company and Temp-cast. Nothing that I could see in Australia at all. I sent emails to a few of these companies, which produce pre cast inner cores for their heater designs and cast iron fittings like doors, grates, ashcovers, dampers etc.
    The concern I had was that these heaters are incredibly bulky and heavy (up to 10 tonnes in total) so freight costs for precast anything from the US to Australia would be prohibitive. Not to mention the ethically questionable practice of burning all that fossil fuel to transport masonry halfway around the world!
    To my surprise, Temp-cast responded to my email, and they have an Australian dealer! I am now hopeful that I will be able to purchase one of their precast core kits locally, and engage a local brick mason to build the external brick veneer and finish the heater in my home. I'll keep you posted with how this all pans out, because as far as I can see, us Aussie permies aren't well acquainted with the benefits of masonry heaters compared to cast iron alternatives.

    Regards,
    Nathan Chattaway
    near Mount Crawford, SA
     
  2. ptpermaculture

    ptpermaculture Junior Member

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    Hi Nathan,

    Have you considered a rocket mass heater? Ianto Evans has a great book for constructing one with lots of detail - https://www.rocketstoves.com/.

    The folk from Milkwood also have a good post with a lot of info on rocket stoves in general and mass heaters toward the end - https://milkwood.net/2011/06/14/rocket-stove-roundup/

    Paul Wheaton has a podcast (which is characteristically waffly but with bits of useful information between the waffle which compares rocket mass heaters with masonry stoves) https://www.archive.org/download/Pa...aton-permaculture-019-rocket-mass-heaters.mp3

    I hope that helps you in what sounds like an exciting journey.

    May your polycultures be overyielding!
     
  3. nchattaway

    nchattaway Junior Member

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    Hi Harry,

    Yes, I've looked at Rocket Mass Heaters. I bought Ianto's book in PDF format a while ago. But it seems to me that the Rocket Mass Heater is primarily a horizontal design, so you need to lie on it or near it to receive maximum benefit from the radiant heat. The masonry heaters I'm looking at are much more vertical in design, and a human bustling around in the open area where it is located will receive more warmth from this.

    Also, the Rocket Mass Heater as designed in Ianto's book doesn't include a baking oven at all, just a cooktop on the barrel. I have seen Milkwood's rocket water heater for their shower hut - this looks like a great single purpose application. I love the way the greywater from the shower irrigates the willows that they use to fire the rocket heater! True sustainable permaculture in action!

    Thanks for the Paul Wheaton link. I will definitely listen to that.

    I've already heard back from the Australian agent for Temp-cast - they are called ecostoves and located in NSW. I'll post back with options available from them soon.
     
  4. nchattaway

    nchattaway Junior Member

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    Well, the bad news is that Ecostoves, the Australian agent for Canadian Masonry Heater company Temp-cast, don't cast up the Temp-cast core kits locally, but SHIP THEM FROM CANADA! These core kits are specially designed and very complex. They're made from refractory cement blocks, keyed so they are practically idiot proof to assemble. You then cover it in corrugated cardboard and have a brickie build a facade around the core.
    The problem with international shipping of masonry is of course the ridiculous cost involved. I was quoted $10,000 US plus shipping from Sydney to Adelaide, for the core and the iron castings (doors, ash pit covers, damper lever etc). And then you need to assemble it, plus buy and install the brick (or stone etc) facade. So I imagine the cost could run to $13,000 - $15,000 fairly easily. No way is this environmentally friendly or within my price range.

    So, I think I'm back to separate solutions for separate functions: A Rocket Mass Heater for keeping warm and a cast iron woodburning cookstove for food preparation and hot water.
    Can anyone recommend cost effective cast iron stoves? I've heard that Scandia stuff is reasonably cheap (if you call $3000 for a stove cheap!) but quality is shockingly bad.
     
  5. Terra

    Terra Moderator

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    We have a old "Carmichael wood stove" which cost us $200 the house still had the original flue pipes up through overhead cupboards so instillation was easy we also have a wood heater that overnight burns which is ok to heat water cook soups on ect . Wood stove does need a minor tidy up but i figure if its not broken dont fix it , i have reaserched a bit and i could make the firebox a lot deeper which would give us overnight burn in the woodstove . I have seen a fantastic wood stove in a place that had been renovated out of old shearers quarters into a modern style home the stove was massive two ovens and a huge firebox , love one like it would need a crane to shift it .
    You could build a "wall tank" of say a 1000 litres to replace an existing wall and hook up to your stove that would create a pretty good heat sink .
    Care needed if hooking up hotwater system to wood heaters they can boil with obvious nasty burn risks when turning on taps safer to draw of your normal hotwater unit and have the infeed water supplied from a seperate tank hooked up to your stove (no energy required as water is already hot ) also water must be heated to sufficient temperature to be safe from serious bacteria .
     
  6. nchattaway

    nchattaway Junior Member

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  7. whistlerPam

    whistlerPam Junior Member

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    Here is a link for plans to build one which can be made with or without an oven. https://dnr.mo.gov/pubs/pub781.pdf
    If you google Russian stoves there are a bunch of links, most of which I haven't checked out. Aprovecho also has plans for a somewhat smaller version they are working on but I don't think they call it a russian stove, if you check out their website you will find masses of information about stoves, heaters and even an occassional water heating system that they have worked on over the years.

    When the Mennonites and so forth first immigrated to North America many of them hunkered down and built those massive furnace/ovens for their homes so it's certainly doable if you have a strong back. I THINK I read on one site that they were often made from home made brick (I suppose they would have to have been, in many cases) so you might well be able to do the lining in firebrick and the outside in some sort of cob but you would need to research that for yourself. Certainly the beehive ovens used for the summer kitchens were made from a form of cob but they weren't as complicated; I doubt very much pure cob would work.

    Anyway, some food for thought
     
  8. Pakanohida

    Pakanohida Junior Member

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    I live near Ianto, & have visited Cob Cottage when they had an open house a few years ago. The Rocket Mass Heaters radiate warmth through out the entire structure when used. They are built into nearly every single cob building he has there from the Bedrock house to his own home. One of the buildings even have pizza oven built (if I remember right) to recapture the heat as a rocket mass heater inside the home, and then exits elsewhere.

    You could do some amazing construction with a little cob and thought. ;)
     
  9. hardworkinghippy

    hardworkinghippy Junior Member

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    I agree Pakanohida, I'm in the process of building a rocket mass stove and I'm pleasantly surprised at the amount of space heating it can handle.

    Nchattaway, I too had reservations about the horizontal flue and didn't really want just to sit around all day to get the benefit of the heat from the bench. I've put the last five metres of pipe under a bookcase to save space and although I haven't finished cobbing over the pipes yet, the 700² feet (That's 13x5 metres - right ?) room plus some of the space in the floor above is warmed for a good few hours after the stove goes out.
     
  10. Curramore1

    Curramore1 Junior Member

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    I have an Australian made Nectre wood heater with a wet back which is used to heat water and cook on top of from late April to September with my electric as a backup and to use the rest of the year. It cost $1695 2 years ago with the flue kit which I installed myself from BBQ's Galore at Maroochydore. They also make a model with a baking oven. Mine is very small with 15 btu output. They make them much,much larger. Mine uses approx. .15 cubic metres of wood per 24 hours to heat a two story 500 square metre insulated weatherboard house and 200 litres of hot water to 65 degrees C. Mind you I live in a mild climate with winter mins down to 4-5 and mid winter average day temp of 15 degrees C maxing at 19 or 20 degrees C. We have a good heat sink on the western wall to store heat as well. The trees to the North are all deciduous as well. The heater could be surrounded by masonry to absorb and save heat, but may reduce the spread of heat through the house. Our house has good convection with high ceilings and varied rooflines and a solar powered exhaust fan with ducting from the ceiling upstairs to the downstairs. Probably the only downside is that when burning only dried Tallowood the flue needs decoking every 3 months if the flue is choked down for most of the day and night. The water storage in the ceiling is another heat sink, even though insulated it still helps to heat the house.
     
  11. sweetpea

    sweetpea Junior Member

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    There is something so psychologically pleasing about a woodstove, it just makes everything else feel good, especially when the weather feels lousy. It heats the house, you can cook on it, heat water in a tea kettle during the day, attach hot water lines to the back of it, it's just so useful. I supplement the heat with passive solar heating, so I think the woodstove will last a lot longer.

    The longest side of the house faces the sun as it travels across the sky, with big windows, preferably single pane (with thermal curtains in winter to keep heat in at night), tiny eaves, black roof shingles, painted a flat very dark green color (black is a little too depressing!) and it's not up on piers at all, so no cold, windy air underneath it. It is fully insulated, ceiling, walls and floor. Lately it's gotten down to just freezing at night and the inside stays 20 degrees warmer (F), and it will heat up inside during a sunny day another 20 degrees higher than that (F), like a pleasant summer day temp. I can feel the heat coming in the windows on a sunny morning even if there's some frost outside, I think the windows are one of the main helpers. The insulation is crucial for keeping the heat in, especially in the ceiling. We have a separate family room that isn't insulated, but is in the sun and it's freezing by morning.

    This site has some great passive solar add=ons:

    https://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

    And I like this gizmo:

    https://www.motherearthnews.com/Do-It-Yourself/1977-09-01/Mothers-Heat-Grabber.aspx

    Here's a diagram of a similar one:

    https://www.builditsolar.com/Projects/SpaceHeating/mssungrabber.htm
     
  12. kurrajong

    kurrajong New Member

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    Masonry Heaters are available in Australia

    I thought I should post a few bits to clarify some misunderstandings. Masonry heaters are available in Australia - we provide them. We were Ecostoves but changed our name to Heavenly Heat earlier this year. The cost of a standard masonry heater is about $7500 for the core. If you want one with lots of extra's it is more. The extra cost is up to you. If you use recycled brick, stone from your property, and build it yourself, then the extra cost is virtually $0. If you choose to buy an expensive facing and have someone else build it, it will be more, but it isn't hard to build. It isn't complex, it is easy to put together yourself.
    Yes, we do ship the heater in from Canada. There isn't a big enough demand to have them manufactured in Australia yet. The waste in producing one heater at a time would be excessive and until a larger market is established, bringing them from Canada in batches and transporting direct from the ship to the person buying the heater is the efficient approach available.
    If you are looking at a traditional wood heater, there are some good ones available. But you really need to look at efficiency and emission levels, and you need to operate them in a way that MINIMISES emissions (ie - so you can't see smoke when they are operating). Masonry heaters are designed to minimise operator 'bad practice'. On the whole the cheap models don't have good efficiency or produce higher emissions.
    We originally brought our heater in from Canada because after lengthy investigations and consideration of building one ourselves, we decided against it. As we couldn't buy one here we brought one in from Canada. It was fantastic. We realised it used far less wood, produced less emissions (it doesn't smoke), continued to heat the house for 12 - 18 hours after the fire was out, didn't need stoking, .... The more we used it, the more we loved it. Having grown up with traditional wood heaters, I wouldn't go back to one. So, after using it for a year we thought we really had to bring them to Australia because they were so good - starting a business based on something you think is a really good product and use yourself seemed sensible.
    We will be at the Practically Green Festival that is being held by Nillumbik Council (Eltham) on Sunday 21 October. If you have any questions, please come and talk to us, or look on our web site (www.heavenlyheat.com.au). Fiona & Alan
     
  13. Donkey32

    Donkey32 Junior Member

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    Rocket Stoves

    I've been experimenting with and building Rocket Stoves for over a decade now..
    The horizontal bench thing is NOT necessary. You can build the storage mass any way you want. Under floor, thermal/radiant dividing wall, heated statue of the Archangel Gabriel.. The bench IS very yummy, though there are quite a lot of practical ways to use the heat, including ovens, bells, etc.

    What makes Rocket Stoves so useful and versatile (besides the efficiency of burn) is that it separates the functions of producing heat (very efficient fire) and using the heat (piped off to whatever). There is no particular form that is required and the exhaust can be piped below the level of the fire itself. ( I know the last bit is hard to believe, nonetheless, there it is.)
     
  14. 9anda1f

    9anda1f Administrator Staff Member

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    Great new article on a rocket oven: https://permaculturenews.org/2012/11/08/rocket-oven-nitty-gritty/#more-8645

    From the story:
     
  15. Bangyee

    Bangyee Junior Member

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    This is gold, just what I was looking for. I had this dilemma, that rocket stoves might not be suitable for long, slow baking and roasting (many many hours on evenly low temperature). This rocket oven might not itself be the solution, but it gives ideas. I think for above purpose something with more thermal mass would be benefitial and the automatic fuel feed would need to be solved somehow. Reason being not to have to come back every 30 minutes and struggle to keep the temperature fluctutating from spikes of firing up the burn chamber then leaving it cool back down...
     
  16. Donkey32

    Donkey32 Junior Member

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    Firstly, metal will NOT last long inside a Rocket Stove burn unit.. The high temperature (1000 C. +), high velocity, high excess O2, low carbon environment chews through steel quick-time!
    High mass ovens can help to alleviate the constant feed issue a little, though with a Rocket Stove J-tube, constant feeding is a bit of a given.. You can switch to what is now known as a Rocket Batch-box heater, which is relatively new. Batch-boxes look more like a conventional stove, can be fed regular cord wood and have EXTREMELY high output of heat.

    Here are some threads over on the donkey32 Rocket Stove forum that might interest you:
    https://donkey32.proboards.com/thread/1301/all-adobe-mud-cookstoves-ovens
    https://donkey32.proboards.com/thread/1279/outdoor-living-rocket-cooker-heater

    This last is about the Batch-box, it's a huge, long thread that documents the development of the stove.. I'm linking into the middle, where 'ol Peter is narrowing in on the design:
    https://donkey32.proboards.com/thread/511/adventures-horizontal-feed?page=5
     
  17. Bangyee

    Bangyee Junior Member

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    Holy smokes those dragon art stoves are awesome!And all the info in those threads... amazing. I will have some learning to do I think!Would stainless steel also die in the rocket? I found it weird that the guy from that article said in the comments his new favourites are red building bricks... surely that can't take the heat?
     
  18. Donkey32

    Donkey32 Junior Member

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    Stainless will last longer than other steels, but it will burn out too. Don't really need to worry about it with the little cook stoves, but when you step up to 6 inches or larger (15.24 cm) stoves, metal is a temporary item. I know of stove builders that INSIST on using metal and will stop down their larger stoves to cool them off and avoid burn-out.. This is a HUGE mistake, efficient combustion requires high temperatures, slowing the fire works in the wrong direction to that end.

    Red-brick will stand up a lot better than you would think. The best (of the red brick) is antique, soft (and light), mid grade bricks. I've seen medium sized Rocket Stoves out of red-brick last for many years. Crummy red brick can sometimes out perform the high temperature fire-bricks.. Firebrick are designed for high temperatures, but are less able to handle heat shock from fast hot/cool cycles. It is a bit of a crap-shoot, antique brick was made close to home, out of whatever grade clay was handy. Sometimes you get the good stuff, sometimes you don't.
     
  19. Bryant RedHawk

    Bryant RedHawk Junior Member

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    You can certainly build a RMS with a cooktop and an oven, several have been built already. What you do is build the J tube then the first riser (bell) is used to heat the 1/4 to 1/2 inch thick range top, there is a second bell put in place behind the first one and you build the oven into that one, from there the heated air flows down to the horizontal mass to extract the rest of the heat before it goes up the chimney tube to the outdoors. With proper designing you can have a cook top, oven and thermal mass heater in one unit. My wife and I are in the design stage of a batch box style RMS with a cook top, oven and warming box. I plan on it also being the heating unit for the house we are building since there will be enough thermal mass in this unit to heat the 1050 sq. ft. we are building.

    View attachment 2841 a schematic View attachment 2842 a working stove with cooktop and oven.
     

    Attached Files:

  20. songbird

    songbird Senior Member

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    it looks on your diagram that the smoke/exhaust from the fire goes into the oven?
     

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