9 ms·

Masonry Heaters: 18-24 hours of heat output from a single wood fire

147 points by gjsman-1000 4y ago

macmac 4y ago
Malwarebytes flags this site as having a Trojan.
- gjsman-1000 4y ago
  Well, then it's wrong. https://www.virustotal.com/gui/url/3d43fe6f2a5b96525b5b76817378576457846ecb19e2e7ea9a876b7c723b169a https://www.virustotal.com/gui/url/3d43fe6f2a5b96525b5b76817...
- devwastaken 4y ago
  3rd party AV is useless in modern computing. Ublock origin and knowing your file extensions is a significantly better solution.
- sp332 4y ago
  It's also blocked by Plume routers, but it's not categorized as anything specific.
- yazzku 4y ago
  Malwarebytes is the trojan. Let the NSA earn their paychecks.
pjkundert 4y ago
If you want a lot of background on designing and building an effective “rocket stove” (the core of a masonry heater), you’ll enjoy this: https://batchrocket.eu/en/building https://batchrocket.eu/en/building
world2vec 4y ago
My parents have a fire stove like those ones in their house, built almost 30 years ago. Not a common design in the country they live but apparently it is in Switzerland where they worked for many years before. Very efficient indeed.
- Dma54rhs 4y ago
  This is also common and very old tech in all the colder countries in Eastern Europe but obviously electricity has taken over. I'm even a bit surprised because I'm having a hard time thinking how else would you hear your house but probably it's enough in milder climates to not store the energy like that.
  - world2vec 4y ago
    It is a milder climate but still cold winters. People usually have small wood stoves or electric space heaters. It's just they're all not very efficient when compared to these masonry heaters.
fwlr 4y ago
You have to follow a few links to get to a definition of what masonry heaters actually are, but it ends up at https://www.mha-net.org/docs/def-mha.htm https://www.mha-net.org/docs/def-mha.htm Specifically the important parts: “a mass of at least 800 kg. (1760 lbs.)”, “an overall average wall thickness not exceeding 250 mm (10 in.)”, “external surface of the masonry heater … does not exceed 110 C. (230 F.)”, “at least one 180 degree change in flow direction” of the released gas. Essentially, it’s a rocket stove and a large thermal mass of masonry, and the masonry has a few design restrictions to meet certain performance characteristics (i.e. it should absorb most of the heat released by the stove and it shouldn’t release that heat too quickly from any particular point on the mass). Mostly I’m surprised it’s that easy; I would have thought anything that can radiate heat slowly and consistently would by necessity also absorb heat slowly and consistently, making it difficult to capture most of the heat from a fast-burning stove.
- a9h74j 4y ago
  > I would have thought anything that can radiate heat slowly and consistently would by necessity also absorb heat slowly and consistently Something like a ratio of flame-side heat absorption at flame temperatures, to room-side emissivity at room-side temperatures(wavelengths)?? This could fall out from material properties without appearing as an explicit design detail (e.g. a surface treatment).
- bcbrown 4y ago
  > Mostly I’m surprised it’s that easy; I would have thought anything that can radiate heat slowly and consistently would by necessity also absorb heat slowly and consistently, making it difficult to capture most of the heat from a fast-burning stove. My understanding is that this is the motivating principle for the "bell" part of a rocket stove masonry heater. The hot exhaust from the combustion chamber is piped into a massively larger enclosed airspace, which has an exhaust port at the very bottom. Since hot air rises and cool air falls, most of the heat in the exhaust will be absorbed by the bell enclosure before finally being vented through the exhaust port. By enclosing the bell in masonry, it meets the design restrictions you mention. I think it's also possible to build a masonry heater without using rocket stove principles, just a fireplace with a huge mass of masonry surrounding it. In that case, you'd want cladding with somewhat high thermal conductivity to capture the exhaust heat, but it's thick enough that the solution to the Fourier heat equation [0] is low enough to meet the design restrictions. [0] https://en.wikipedia.org/wiki/Heat_equation#Heat_flow_in_a_uniform_rod https://en.wikipedia.org/wiki/Heat_equation#Heat_flow_in_a_u...
skybrian 4y ago
The electric version of this is called "electric thermal storage" where the electric heater is used off-peak to heat up ceramic bricks. It seems unlikely to beat a heat pump, though. Could they be combined?
- Gibbon1 4y ago
  I'd tried to do back of the the envelope calcs for that sort of thing. Resistive heat has the property that efficiency doesn't change with temperature. So you can heat a small amount of bricks to oven temp with no loss. But heat pump efficiency is very dependent. So yeah in theory you could use a heat pump to heat a heat reservoir. Where I get stuck is detailed calcs are needed to suss out the economics. That people don't tend to do this says the economics aren't strongly in favor.
  - thenickdude 4y ago
    Heatpump hot water is an application of this, allowing the tank of water to be heated during off-peak electricity times and act as a thermal battery.
  - tgsovlerkhgsel 4y ago
    1 metric ton of water heated by 10 K stores roughly 10000 kcal or around 12 kWh. A rule of thumb from https://www.greenmatch.co.uk/green-energy/central-heating-capacity https://www.greenmatch.co.uk/green-energy/central-heating-ca... suggests 1 kW of heating per 10 square meters (that's likely the output that's required to maintain an adequate temperature during the n-th percentile coldest days). So on a cold day, a 50 square meter apartment would need 24*5 = 120 kWh. I'd say it's pretty impractical unfortunately. Water is already the best (practical) choice in terms of heat stored per weight, and likely also per volume, and cost.
    - Gibbon1 4y ago
      Last time I tried working things out it seems like concrete exterior walls with hydronic heat and external insulation would be a partial solution. But not really a thing you can add to most existing housing stock. And not a thing in the US. Roughing it I think if you used batteries you'd need to supply maybe guessing here 80kwh during the evening and night time. With a heat pump you'd need 20kwh. That's doable. Course likely over all more efficient to let the utility handle the battery end of things. Then again maybe a masonry heater makes sense if you often have excess solar and your utility is screwing you.
twawaaay 4y ago
I built one with my father when I was a kid. It was dual purpose cooking range and a huge mass of bricks for heat capacity. It was built at the spot where multiple walls met in the centre of the house to increase mass of bricks in contact and to heat multiple adjacent rooms. The walls in those rooms would typically be too hot to touch. One weakness of our setup was that it would suck the air out of the house through the night. Another was that complex internal tunnels made the maintenance difficult. If I built one today I would make sure to fix it and create a sort of heat exchanger for coming air.
- thriftwy 4y ago
  In Russian stove there's usually a "throttle" - a metal sheet which may be inserted into the exhaust to completely block loss of heat via air sucking. Obviously you must ensure that fire is no longer burning before closing it.
  - ghaff 4y ago
    Wood stoves typically have a damper as well. You open it until you have a good draft going and then you close it. It doesn't block off the flue entirely but it keeps a lot of the heat from going up the chimney.
- numbsafari 4y ago
  I was in Argentina, spent a day visiting outdoor markets to buy some art, and hit up a recommended pizza place for an early dinner (8pm). Having been out all day, I needed to use the restroom. Turns out the bathroom shared a brick wall with the back of their wood ovens. So this bathroom was like a fucking oven, and super compact. I touched the wall like an idiot and burned my hand. The pizza was excellent.
  - culopatin 4y ago
    I’m assuming you’re from the US. What is different about the Argentinian cheese in your opinion? Why is it so oily and flavorful compared to American mozzarellas? I could never replicate an Argentinian pizza in the US because of this. Also did you have a la piedra or al molde?
ghaff 4y ago
It's an interesting idea although I assume it has to be somewhat baked into new house/addition construction. A big downside of conventional wood stoves I find is that, if I'm not going to be hanging out at home--mostly around where the fire is--for the day it's not really worth it a lot of the time. I fire up my wood stove mostly when it's especially cold and I'm not primarily working in my office.
- PenguinCoder 4y ago
  Same here. The woodstove I have heats the main room fine but doesn't really reach well to what I use as an office. I use it as supplemental heat source, not primary. Getting it going and then into maintenance mode is a good hour or so of prep. Then needing to refill it at least once in the day. When I run it during the work day I'll generally work in the same room just to keep an eye on it. Some days that's not worth it. Some days it's -20F out and totally worth it.
  - ghaff 4y ago
    Yeah. I mostly set it up if I'm mostly going to be working on a laptop, reading, on mostly one-way video in my "sunroom" where the stove is--which also happens to be a fairly new well-insulated room when it's really chilly given that my house as a whole is a 200 year-old farmhouse.
mmastrac 4y ago
I vaguely recall seeing a YouTube video about some folks living in Siberia and using these to keep their homes warm.
thriftwy 4y ago
Did they just invent a Russian stove? https://en.m.wikipedia.org/wiki/Russian_stove https://en.m.wikipedia.org/wiki/Russian_stove Now when the end game is known, perhaps it is better to just adopt the existing designs instead of trying to perfect the current product.
- camtarn 4y ago
  One of the videos shows other examples of similar designs, dating back to ancient China. I don't think they're claiming to have invented anything; just promoting an old but still useful technology.
denotational 4y ago
> rapidly and cleanly burn a large charge of wood I was under the impression wood-burning stoves produce very high amounts of particulate pollution, is “clean” really an accurate claim?
- gjsman-1000 4y ago
  Used to, not anymore. Old wood stoves produced as much as 50+g./hr. of particulate matter, current standards are 2.5g./hr. for cord wood for new EPA-certified wood stoves since 2015. Most masonry heaters constructed in the last 20 years are in the 1-3g/hr. range (and for this reason have never needed EPA certification).
- cperciva 4y ago
  I think "clean" is intended relative to other wood-burning stoves. Because this design of stove burns at relatively high temperature, it yields more complete combustion and emits lower levels of particulate.
  - daneel_w 4y ago
    > " Because this design of stove burns at relatively high temperature, it yields more complete combustion and emits lower levels of particulate." This doesn't sound right to me, because there's heavy soot production whether hot or cold stove. Are you sure it's not just because a large masonry stove (and its long chimney) has a lot more surface for soot and particulate to stick on compared to e.g. a tiny portable one?
    - Ekaros 4y ago
      Not too much soot should be produced in well designed burning. Which includes sufficient input of oxygen. Ofc, also the material burned matters. Only untreated wood and with right moisture level. The emissions increase with both too wet and too dry wood.
      - bcbrown 4y ago
the_third_wave 4y ago
I heat my home with a version of this idea, this being a cast-iron wood-burning stove connected to a "rörslinga" - a chimney flue manifold which first goes up, then left, then down to the floor, right and then up again. This flue continues upwards through a massive brick chimney I built which contains 6 channels, 1 of these being a ventilation shaft, the other 5 flue channels for different wood-burning devices. The chimney is uninsulated and goes through the unheated but well-insulated 2nd floor, then through the roof. The flue gas temperature at the top of the chimney is well below 100°C since most heat has been deposited in the lower sections of the chimney. This way we heat our 17th century farmhouse with the mentioned stove and a wood-burning kitchen stove ("vedspis" in Swedish) which is built into a massive brick enclosure which also absorbs heat. The combination of the quick-heating cast-iron stove (A Jøtul F400, 7 kW nominal, 84% efficient) and the "rörslinga" provides both quick heat for getting the room up to temperature as well as lasting heat for the night. It generally only takes a single good fire to warm up the place and keep it warm through the night followed by a small fire in the morning to bring up the temperature a bit. When it gets cold outside - -15°C or below - I tend to add an extra load of wood late in the evening which burns for a few hours in the night, that way it'll be around 18°C in the morning. The sleeping rooms upstairs are kept warm by opening the door to upstairs in the evening and opening the doors to the rooms so warm air from below can come in. This way the temperature there end up around 15°C which is just where I want it to be - not too cold and above all not too warm. There is a "rörspis" - a free-standing masonry stove with integrated "rörslinga" in the house as well but I have yet to renovate it so we do not use it yet, also because we can keep it warm enough using the two heat sources we now use. Next to those there is a wood-burning oven built into foot of the chimney (or "murstock" as it is called in Swedish) which sees very occasional use. I also made a connection for a stove on the 2nd floor but have not connected it yet because of a lack of need, it gets warm enough the way it is now. Total wood consumption for the house lies between 4m³ and 7m³ per year depending on winter temperatures and types of wood, this includes wood used for cooking. I have yet to cut a living tree for firewood as there always is enough storm-felled wood in our 15 hectares of forest to satisfy our needs.
hkgjjgjfjfjfjf 4y ago
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cortesoft 4y ago
Are these legal in a place like California, where you aren’t allowed to build new wood fireplaces in a building? Edit: did a bit of research, apparently it is a “particulate per hour” restriction, not a general wood fireplace restriction. This might meet the requirements.
frereubu 4y ago
Looks very similar to the kinds of oven stoves and heat walls in https://www.lowtechmagazine.com/2008/12/tile-stoves.html https://www.lowtechmagazine.com/2008/12/tile-stoves.html, which I found quite inspiring.
- pcdoodle 4y ago
  Damn, these are cool
haunter 4y ago
My parents have this in Hungary. In fact most old houses does. Usually it’s very and plain square design like this https://www.ohegyi-cserepkalyhas.hu/images/cserepkalyha-sarga-torokmintas-bontas-tarolas.jpg https://www.ohegyi-cserepkalyhas.hu/images/cserepkalyha-sarg... But it can be fancier too, more arts-y tiles or building the heater in a shape where you can sit down etc. Anyways it’s incredibly good! You really only need a single small fire and the heat can last a long time. Perfect for cold winter nights.
- vasco 4y ago
  Old regular polish houses and generally castles and palaces through northern Europe make use of the same device you shared by I'm not sure it's the same thing as OP.
  - saiya-jin 4y ago
    Not the same thing per se, but same principle - you have big mass absorbing much more of the heat produced by burning, and then slowly glowing it off for another 12-24h. We have same in Czech republic and Slovakia, physics of it are simple and discovered probably millennia ago and people also install it in new homes (I know few newly built homes it massive stove like this). You can actually ie bake bread in it if construction allows it. My parents have another kind of stove - they can switch mode to a regime which doesn't burn the wood violently in 1h but rather lets it burn slowly for around 8-10h. The stove looks like generic small ones, but if you load it in the evening it still radiates a bit of heat in the morning from just few pieces of wood. They can easily make it through harsh winter with just this and moderate pile of wood, even if cut off form everything.
- paganel 4y ago
  We have the same wood stoves here in neighbouring Romania. Whenever I go visit my parents in the countryside and they heat up the stove I realise how cool of a "technology" it is, that is to still have a heat source many hours after the fire the had done its thing. Unfortunately building/making wood stoves is a dying art, you can find less and less people who are good at it. And the trouble is that if you build a defective wood stove you risk all sorts of nasty stuff, like dying from carbon monoxide intoxication.
cactusplant7374 4y ago
Is this the sort of heat release that leads to opening the windows?
Timothycquinn 4y ago
I'm really temped to build one of these for my Woodshop. Was just concerned with the danger of some butt head accidentally leaning wood up against it. I assume that would only be a problem with the front of the unit if its a double walled one like this: https://www.youtube.com/watch?v=GfygkTCLDtw&t=1359s https://www.youtube.com/watch?v=GfygkTCLDtw&t=1359s
doubleg72 4y ago
I live in Pennsylvania and have a Fireplace Xtrordinaire fireplace that came with this house and similar to this. It sucks in air from outside, which is routed around the firebox and heated before being forced into the room. It's called a positive pressure fireplace and it really does heat the 2500 square ft house well. Another cool technology with this fireplace is the catalytic combuster, which allows for almost complete combustion by burning off anything left in the smoke after reaching a certain temp. I sometimes wonder though, is better to have a negative pressure living space pulling dry, cool air into the house rather than positive pressure, forcing warm, moist air through any and all crevices throughout the house. I guess time will tell..
- denimnerd42 4y ago
  sounds like it would generate condensation for sure where the cracks in your barriers allow that warm air to hit cold.
- pojzon 4y ago
  2500 sq ft is ~ 232m2 for ppl in countries with normal unit.
  - dylan604 4y ago
    sq ft is perfectly normal. while you might like your metric measurements, it is sad that people need someone else to do this for them. if you don't like the units, convert it. but to call it abnormal is just an insult to those that think of it as normal. thank you and have a nice day. please drive through
    - Hyption 4y ago
      From an international standpoint, it's very unnormal though.
      - pojzon 4y ago
        US academy is using the metric system for calculus because they also think imperial system is unpractical. Its just a matter of cultural change in society.
kerpotgh 4y ago
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at_a_remove 4y ago
One possible improvement on these would be the use of feolite, a sort of brick of iron oxides. It has a heat capacity far above that of normal brick and is used in electric heat storage systems. The heat capacity may be in excess of what was listed on Wikipedia, I did some digging in hopes of finding the exact composition only to find that some research projects on this material indicated an even greater heat capacity than the official numbers. And its volumetric heat capacity is staggering.
yboris 4y ago
Related: rocket mass heater "A rocket mass heater (RMH), also known as rocket stove mass heater, is a form of slow-release radiant heating system, designed to primarily heat people and secondarily to warm areas in line of sight around it." https://en.wikipedia.org/wiki/Rocket_mass_heater https://en.wikipedia.org/wiki/Rocket_mass_heater
hedora 4y ago
I imagine this design working well up north, where temperatures are low, but don’t move much within a 24 hour window. We have a passively heated house, and use a standard modern wood stove. It has some stones inside it to hold a bit of heat, but only stays warm for about an hour after the fire is out. It is >80% efficient and has similar emissions to these. They run $1-2K in the US. Here are some examples: https://www.blazeking.com/product-category/wood/ https://www.blazeking.com/product-category/wood/ (These tend to be heavily regulated with different manufacturers in each country producing similar stoves.) It has a built in thermostat/oxygen regulator, and can run for up to 24 hours without reloading (8-12 hours is more realistic; they advertise 40 hours on bigger models). Instead of using exterior air through an inlet, it pulls air from the house. The outside of the stove looks traditional, but is actually a cleverly designed convection heatsink, so it doesn’t need a blower. (For tiny homes or trailers, you still need an inlet from the outside.) Anyway, for modern construction at mid to low latitudes, I think this approach is much better than a masonry stove. In particular, we can turn the stove down in the morning, and up in the evening by turning a knob. We had a masonry-style stove where I grew up, and it was fine. That house was older (and shaded by trees), so it didn’t really passively heat during the day. That’s an appropriate use case for big masonry thermal masses.
sneak 4y ago
Reminder: it is extremely bad for your health and the health of those around you to burn wood and release woodsmoke, even up/out of a chimney. https://www.samharris.org/blog/the-fireplace-delusion https://www.samharris.org/blog/the-fireplace-delusion It smells nice but it is damaging your heart and lungs and those of people within a quarter mile radius.
- gjsman-1000 4y ago
  The truth is always more nuanced in reality. 1. He wrote that in 2012, citing a study from 2007. Standards for wood stoves have changed. Old wood stoves and open fireplaces are unquestionably dirty - in the 30-50 grams of particulate released per hour, sometimes more. But is it fair to compare them to, say, modern EPA standards which have a 2.5 gram limit per hour which took effect in 2015, or the 4.5 gram limit from 2012? I don't believe so. Sure, if you still have that ancient 80s wood stove still in your house, it's unquestionably far more dangerous than a modern product. The masonry heaters in this original post have been hitting 1-3 grams of particulate for over 30 years now. Some heaters managed to score less than 1 gram of particulates released in MHA EPA-certified testing in 1998, beating standards decades ahead of time. 2. "The case against burning wood is every bit as clear as the case against smoking cigarettes." This is an argument that proves too much - because the exact same arguments about "creating pollution you can't dispose of" is equally valid of cars. It's also, arguably, equally valid for when you buy unnecessary products on Amazon, or do any CO2-emitting activity. You would have to show it is a particularly unconscionable level of emissions - which, with modern efficiency meaning you can get about 20~25 fires in a modern device for the damage of a single campfire... if you are going to burn wood, I'd prefer you had a modern wood stove habit than a campfire habit.
- lostlogin 4y ago
  If you are smelling a fire from 1/4 mile away, someone is burning some wet wood or they have a very crappy wood burner.
Awelton 4y ago
I work for a company that (among many other things) designs and builds custom full stone masonry fireplaces. Almost all of our customers in Northern climates are heating huge mansions with two or three fireplaces and absolutely swear by them, to the point where the fireplaces are designed first and the rest of the residence is planned around them. Once you get all that thermal mass warmed up it radiates a surprisingly long time.
WalterBright 4y ago
When I watch "Alone", I'm surprised that I haven't seen anyone yet make a fireplace heater this way. They usually build something that is so inefficient it does little, or fills their shelter with smoke (poisoning them), or burns their shelter down. I'd at the very minimum put large flat rocks in the fireplace, then put them under the bed.
- vl 4y ago
  In the season with couples, one of them built pretty sophisticated temp shelter with fireplace, and then they built even larger shelter with larger fireplace. PS (They lost - instead of concentrating on food, they concentrate on the shelter, which was too sophisticated and took too much energy) PPS I'm also surprised that most of the contestants rarely move from bad locations. I.e. "this location is so bad, there is no good place for the shelter, and no food", but then instead of moving they just stay.
  - WalterBright 4y ago
    I missed that season. Which one is it? It's pretty clear from watching it that it's set up so you'll starve no matter how good you are at hunting/foraging. Then it's all about the energy expenditure. I noticed that the bigger the shelter, the thicker the logs in it, the sooner they tap out from starvation. Me, I'd start with two trees about 10 feet apart and use them as my main posts. Lash a log between them about 7 feet up, and that is the roof ridge. Lean 1" logs against it. Voila! a decent, strong shelter with minimal energy expenditure. Next I'd build a bed a few inches off the ground, to keep it dry and so hot rocks can be pushed under it. Then I'd tap out because I don't know how to hunt or fish. One woman built a decent fireplace out of clay and rocks, but it was a bit too small.
    - vl 4y ago
      Season 4 "Alone: Lost & Found" I really liked it. It was intense and unique - one person from the pair had to hike to location using compass. So they didn’t start together. In Patagonia season one of the women built top-class camp as well and she wasn’t starving too! I disagree about that it’s setup for starvation - quite often there is single or maybe two participants that get enough food. It is surprising though that quite often they obviously don’t pay enough attention to food and just starve. Ie they would try to fish in the same spot and not get fish over and over and so on. I don’t have enough training to do that, but strategy-wise I would tap out if me trajectory was negative. Ie if I’m obviously not getting enough food or fail to have warm shelter as cold arrives, I would just tap out.
nine_k 4y ago
I wonder why it's historically not the default in a lot of places, while the default is a fireplace with half of its enclosure protruding to the outside of the building (which strikes me as insane). What could historically lead to prevalence of such a bizarre design?
jnsaff2 4y ago
I have a Tulikivi Soap Stone heat retaining ovens [0] in my home. It stores about 60kWh and releases it gradually over 24+h. The problem is that it's power is about 3kW of released heat. Which is not enough for my home. I still need to use heat pumps as my main heat source (not complaining as they are more efficient anyway). So it's a nice fireplace that retains heat and the cats really love it. But there is a tradeoff between power and efficiency so if you are looking to put one in, do the math and figure out whether it is the right solution for you. They also claim that over 90% of the burning energy goes to heating the home and only 10% is lost. Tho as mine uses inside air I suspect that as cold air is drawn in, it might be less. [0] https://www.tulikivi.com/en/Products/Fireplace_collection https://www.tulikivi.com/en/Products/Fireplace_collection
jeffrallen 4y ago
In Ticino they were called pina. They were built between rooms, so that they heated the living room and also the master bedroom.
FooBarBizBazz 4y ago
1. I haven't yet seen the Korean Ondol mentioned in this thread: https://en.m.wikipedia.org/wiki/Ondol https://en.m.wikipedia.org/wiki/Ondol 2. It would be interesting to revive the old Roman hypocaust system, with the benefit of modern rocket-stove design knowledge. 3. Going the other direction, a hyper-modern system based of full gasification, followed by clean combustion of the syngas -- something that looked more like a chemical plant than an oven -- would be interesting, if maybe not actually simple/robust enough to be a good idea. Would like to see it tried though.

147 points by gjsman-1000 4y ago

macmac 4y ago

Malwarebytes flags this site as having a Trojan.

gjsman-1000 4y ago
Well, then it's wrong. https://www.virustotal.com/gui/url/3d43fe6f2a5b96525b5b76817378576457846ecb19e2e7ea9a876b7c723b169a https://www.virustotal.com/gui/url/3d43fe6f2a5b96525b5b76817...
devwastaken 4y ago
3rd party AV is useless in modern computing. Ublock origin and knowing your file extensions is a significantly better solution.
sp332 4y ago
It's also blocked by Plume routers, but it's not categorized as anything specific.
yazzku 4y ago
Malwarebytes is the trojan. Let the NSA earn their paychecks.

pjkundert 4y ago

If you want a lot of background on designing and building an effective “rocket stove” (the core of a masonry heater), you’ll enjoy this: https://batchrocket.eu/en/building https://batchrocket.eu/en/building

world2vec 4y ago

My parents have a fire stove like those ones in their house, built almost 30 years ago. Not a common design in the country they live but apparently it is in Switzerland where they worked for many years before. Very efficient indeed.

Dma54rhs 4y ago
This is also common and very old tech in all the colder countries in Eastern Europe but obviously electricity has taken over. I'm even a bit surprised because I'm having a hard time thinking how else would you hear your house but probably it's enough in milder climates to not store the energy like that.
- world2vec 4y ago
  It is a milder climate but still cold winters. People usually have small wood stoves or electric space heaters. It's just they're all not very efficient when compared to these masonry heaters.

fwlr 4y ago

You have to follow a few links to get to a definition of what masonry heaters actually are, but it ends up at https://www.mha-net.org/docs/def-mha.htm https://www.mha-net.org/docs/def-mha.htm Specifically the important parts: “a mass of at least 800 kg. (1760 lbs.)”, “an overall average wall thickness not exceeding 250 mm (10 in.)”, “external surface of the masonry heater … does not exceed 110 C. (230 F.)”, “at least one 180 degree change in flow direction” of the released gas. Essentially, it’s a rocket stove and a large thermal mass of masonry, and the masonry has a few design restrictions to meet certain performance characteristics (i.e. it should absorb most of the heat released by the stove and it shouldn’t release that heat too quickly from any particular point on the mass). Mostly I’m surprised it’s that easy; I would have thought anything that can radiate heat slowly and consistently would by necessity also absorb heat slowly and consistently, making it difficult to capture most of the heat from a fast-burning stove.

a9h74j 4y ago
> I would have thought anything that can radiate heat slowly and consistently would by necessity also absorb heat slowly and consistently Something like a ratio of flame-side heat absorption at flame temperatures, to room-side emissivity at room-side temperatures(wavelengths)?? This could fall out from material properties without appearing as an explicit design detail (e.g. a surface treatment).
bcbrown 4y ago
> Mostly I’m surprised it’s that easy; I would have thought anything that can radiate heat slowly and consistently would by necessity also absorb heat slowly and consistently, making it difficult to capture most of the heat from a fast-burning stove. My understanding is that this is the motivating principle for the "bell" part of a rocket stove masonry heater. The hot exhaust from the combustion chamber is piped into a massively larger enclosed airspace, which has an exhaust port at the very bottom. Since hot air rises and cool air falls, most of the heat in the exhaust will be absorbed by the bell enclosure before finally being vented through the exhaust port. By enclosing the bell in masonry, it meets the design restrictions you mention. I think it's also possible to build a masonry heater without using rocket stove principles, just a fireplace with a huge mass of masonry surrounding it. In that case, you'd want cladding with somewhat high thermal conductivity to capture the exhaust heat, but it's thick enough that the solution to the Fourier heat equation [0] is low enough to meet the design restrictions. [0] https://en.wikipedia.org/wiki/Heat_equation#Heat_flow_in_a_uniform_rod https://en.wikipedia.org/wiki/Heat_equation#Heat_flow_in_a_u...

skybrian 4y ago

The electric version of this is called "electric thermal storage" where the electric heater is used off-peak to heat up ceramic bricks. It seems unlikely to beat a heat pump, though. Could they be combined?

Gibbon1 4y ago
I'd tried to do back of the the envelope calcs for that sort of thing. Resistive heat has the property that efficiency doesn't change with temperature. So you can heat a small amount of bricks to oven temp with no loss. But heat pump efficiency is very dependent. So yeah in theory you could use a heat pump to heat a heat reservoir. Where I get stuck is detailed calcs are needed to suss out the economics. That people don't tend to do this says the economics aren't strongly in favor.
- thenickdude 4y ago
  Heatpump hot water is an application of this, allowing the tank of water to be heated during off-peak electricity times and act as a thermal battery.
- tgsovlerkhgsel 4y ago
  1 metric ton of water heated by 10 K stores roughly 10000 kcal or around 12 kWh. A rule of thumb from https://www.greenmatch.co.uk/green-energy/central-heating-capacity https://www.greenmatch.co.uk/green-energy/central-heating-ca... suggests 1 kW of heating per 10 square meters (that's likely the output that's required to maintain an adequate temperature during the n-th percentile coldest days). So on a cold day, a 50 square meter apartment would need 24*5 = 120 kWh. I'd say it's pretty impractical unfortunately. Water is already the best (practical) choice in terms of heat stored per weight, and likely also per volume, and cost.
  - Gibbon1 4y ago
    Last time I tried working things out it seems like concrete exterior walls with hydronic heat and external insulation would be a partial solution. But not really a thing you can add to most existing housing stock. And not a thing in the US. Roughing it I think if you used batteries you'd need to supply maybe guessing here 80kwh during the evening and night time. With a heat pump you'd need 20kwh. That's doable. Course likely over all more efficient to let the utility handle the battery end of things. Then again maybe a masonry heater makes sense if you often have excess solar and your utility is screwing you.

twawaaay 4y ago

I built one with my father when I was a kid. It was dual purpose cooking range and a huge mass of bricks for heat capacity. It was built at the spot where multiple walls met in the centre of the house to increase mass of bricks in contact and to heat multiple adjacent rooms. The walls in those rooms would typically be too hot to touch. One weakness of our setup was that it would suck the air out of the house through the night. Another was that complex internal tunnels made the maintenance difficult. If I built one today I would make sure to fix it and create a sort of heat exchanger for coming air.

thriftwy 4y ago
In Russian stove there's usually a "throttle" - a metal sheet which may be inserted into the exhaust to completely block loss of heat via air sucking. Obviously you must ensure that fire is no longer burning before closing it.
- ghaff 4y ago
  Wood stoves typically have a damper as well. You open it until you have a good draft going and then you close it. It doesn't block off the flue entirely but it keeps a lot of the heat from going up the chimney.
numbsafari 4y ago
I was in Argentina, spent a day visiting outdoor markets to buy some art, and hit up a recommended pizza place for an early dinner (8pm). Having been out all day, I needed to use the restroom. Turns out the bathroom shared a brick wall with the back of their wood ovens. So this bathroom was like a fucking oven, and super compact. I touched the wall like an idiot and burned my hand. The pizza was excellent.
- culopatin 4y ago
  I’m assuming you’re from the US. What is different about the Argentinian cheese in your opinion? Why is it so oily and flavorful compared to American mozzarellas? I could never replicate an Argentinian pizza in the US because of this. Also did you have a la piedra or al molde?

ghaff 4y ago

It's an interesting idea although I assume it has to be somewhat baked into new house/addition construction. A big downside of conventional wood stoves I find is that, if I'm not going to be hanging out at home--mostly around where the fire is--for the day it's not really worth it a lot of the time. I fire up my wood stove mostly when it's especially cold and I'm not primarily working in my office.

PenguinCoder 4y ago
Same here. The woodstove I have heats the main room fine but doesn't really reach well to what I use as an office. I use it as supplemental heat source, not primary. Getting it going and then into maintenance mode is a good hour or so of prep. Then needing to refill it at least once in the day. When I run it during the work day I'll generally work in the same room just to keep an eye on it. Some days that's not worth it. Some days it's -20F out and totally worth it.
- ghaff 4y ago
  Yeah. I mostly set it up if I'm mostly going to be working on a laptop, reading, on mostly one-way video in my "sunroom" where the stove is--which also happens to be a fairly new well-insulated room when it's really chilly given that my house as a whole is a 200 year-old farmhouse.

mmastrac 4y ago

I vaguely recall seeing a YouTube video about some folks living in Siberia and using these to keep their homes warm.

thriftwy 4y ago

Did they just invent a Russian stove? https://en.m.wikipedia.org/wiki/Russian_stove https://en.m.wikipedia.org/wiki/Russian_stove Now when the end game is known, perhaps it is better to just adopt the existing designs instead of trying to perfect the current product.

camtarn 4y ago
One of the videos shows other examples of similar designs, dating back to ancient China. I don't think they're claiming to have invented anything; just promoting an old but still useful technology.

denotational 4y ago

> rapidly and cleanly burn a large charge of wood I was under the impression wood-burning stoves produce very high amounts of particulate pollution, is “clean” really an accurate claim?

gjsman-1000 4y ago
Used to, not anymore. Old wood stoves produced as much as 50+g./hr. of particulate matter, current standards are 2.5g./hr. for cord wood for new EPA-certified wood stoves since 2015. Most masonry heaters constructed in the last 20 years are in the 1-3g/hr. range (and for this reason have never needed EPA certification).
cperciva 4y ago
I think "clean" is intended relative to other wood-burning stoves. Because this design of stove burns at relatively high temperature, it yields more complete combustion and emits lower levels of particulate.
- daneel_w 4y ago
  > " Because this design of stove burns at relatively high temperature, it yields more complete combustion and emits lower levels of particulate." This doesn't sound right to me, because there's heavy soot production whether hot or cold stove. Are you sure it's not just because a large masonry stove (and its long chimney) has a lot more surface for soot and particulate to stick on compared to e.g. a tiny portable one?
  - Ekaros 4y ago
    Not too much soot should be produced in well designed burning. Which includes sufficient input of oxygen. Ofc, also the material burned matters. Only untreated wood and with right moisture level. The emissions increase with both too wet and too dry wood.
    - bcbrown 4y ago

the_third_wave 4y ago

I heat my home with a version of this idea, this being a cast-iron wood-burning stove connected to a "rörslinga" - a chimney flue manifold which first goes up, then left, then down to the floor, right and then up again. This flue continues upwards through a massive brick chimney I built which contains 6 channels, 1 of these being a ventilation shaft, the other 5 flue channels for different wood-burning devices. The chimney is uninsulated and goes through the unheated but well-insulated 2nd floor, then through the roof. The flue gas temperature at the top of the chimney is well below 100°C since most heat has been deposited in the lower sections of the chimney. This way we heat our 17th century farmhouse with the mentioned stove and a wood-burning kitchen stove ("vedspis" in Swedish) which is built into a massive brick enclosure which also absorbs heat. The combination of the quick-heating cast-iron stove (A Jøtul F400, 7 kW nominal, 84% efficient) and the "rörslinga" provides both quick heat for getting the room up to temperature as well as lasting heat for the night. It generally only takes a single good fire to warm up the place and keep it warm through the night followed by a small fire in the morning to bring up the temperature a bit. When it gets cold outside - -15°C or below - I tend to add an extra load of wood late in the evening which burns for a few hours in the night, that way it'll be around 18°C in the morning. The sleeping rooms upstairs are kept warm by opening the door to upstairs in the evening and opening the doors to the rooms so warm air from below can come in. This way the temperature there end up around 15°C which is just where I want it to be - not too cold and above all not too warm. There is a "rörspis" - a free-standing masonry stove with integrated "rörslinga" in the house as well but I have yet to renovate it so we do not use it yet, also because we can keep it warm enough using the two heat sources we now use. Next to those there is a wood-burning oven built into foot of the chimney (or "murstock" as it is called in Swedish) which sees very occasional use. I also made a connection for a stove on the 2nd floor but have not connected it yet because of a lack of need, it gets warm enough the way it is now. Total wood consumption for the house lies between 4m³ and 7m³ per year depending on winter temperatures and types of wood, this includes wood used for cooking. I have yet to cut a living tree for firewood as there always is enough storm-felled wood in our 15 hectares of forest to satisfy our needs.

hkgjjgjfjfjfjf 4y ago

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cortesoft 4y ago

Are these legal in a place like California, where you aren’t allowed to build new wood fireplaces in a building? Edit: did a bit of research, apparently it is a “particulate per hour” restriction, not a general wood fireplace restriction. This might meet the requirements.

frereubu 4y ago

Looks very similar to the kinds of oven stoves and heat walls in https://www.lowtechmagazine.com/2008/12/tile-stoves.html https://www.lowtechmagazine.com/2008/12/tile-stoves.html, which I found quite inspiring.

pcdoodle 4y ago
Damn, these are cool

haunter 4y ago

My parents have this in Hungary. In fact most old houses does. Usually it’s very and plain square design like this https://www.ohegyi-cserepkalyhas.hu/images/cserepkalyha-sarga-torokmintas-bontas-tarolas.jpg https://www.ohegyi-cserepkalyhas.hu/images/cserepkalyha-sarg... But it can be fancier too, more arts-y tiles or building the heater in a shape where you can sit down etc. Anyways it’s incredibly good! You really only need a single small fire and the heat can last a long time. Perfect for cold winter nights.

vasco 4y ago
Old regular polish houses and generally castles and palaces through northern Europe make use of the same device you shared by I'm not sure it's the same thing as OP.
- saiya-jin 4y ago
  Not the same thing per se, but same principle - you have big mass absorbing much more of the heat produced by burning, and then slowly glowing it off for another 12-24h. We have same in Czech republic and Slovakia, physics of it are simple and discovered probably millennia ago and people also install it in new homes (I know few newly built homes it massive stove like this). You can actually ie bake bread in it if construction allows it. My parents have another kind of stove - they can switch mode to a regime which doesn't burn the wood violently in 1h but rather lets it burn slowly for around 8-10h. The stove looks like generic small ones, but if you load it in the evening it still radiates a bit of heat in the morning from just few pieces of wood. They can easily make it through harsh winter with just this and moderate pile of wood, even if cut off form everything.
paganel 4y ago
We have the same wood stoves here in neighbouring Romania. Whenever I go visit my parents in the countryside and they heat up the stove I realise how cool of a "technology" it is, that is to still have a heat source many hours after the fire the had done its thing. Unfortunately building/making wood stoves is a dying art, you can find less and less people who are good at it. And the trouble is that if you build a defective wood stove you risk all sorts of nasty stuff, like dying from carbon monoxide intoxication.

cactusplant7374 4y ago

Is this the sort of heat release that leads to opening the windows?

Timothycquinn 4y ago

I'm really temped to build one of these for my Woodshop. Was just concerned with the danger of some butt head accidentally leaning wood up against it. I assume that would only be a problem with the front of the unit if its a double walled one like this: https://www.youtube.com/watch?v=GfygkTCLDtw&t=1359s https://www.youtube.com/watch?v=GfygkTCLDtw&t=1359s

doubleg72 4y ago

I live in Pennsylvania and have a Fireplace Xtrordinaire fireplace that came with this house and similar to this. It sucks in air from outside, which is routed around the firebox and heated before being forced into the room. It's called a positive pressure fireplace and it really does heat the 2500 square ft house well. Another cool technology with this fireplace is the catalytic combuster, which allows for almost complete combustion by burning off anything left in the smoke after reaching a certain temp. I sometimes wonder though, is better to have a negative pressure living space pulling dry, cool air into the house rather than positive pressure, forcing warm, moist air through any and all crevices throughout the house. I guess time will tell..

denimnerd42 4y ago
sounds like it would generate condensation for sure where the cracks in your barriers allow that warm air to hit cold.
pojzon 4y ago
2500 sq ft is ~ 232m2 for ppl in countries with normal unit.
- dylan604 4y ago
  sq ft is perfectly normal. while you might like your metric measurements, it is sad that people need someone else to do this for them. if you don't like the units, convert it. but to call it abnormal is just an insult to those that think of it as normal. thank you and have a nice day. please drive through
  - Hyption 4y ago
    From an international standpoint, it's very unnormal though.
    - pojzon 4y ago
      US academy is using the metric system for calculus because they also think imperial system is unpractical. Its just a matter of cultural change in society.

kerpotgh 4y ago

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at_a_remove 4y ago

One possible improvement on these would be the use of feolite, a sort of brick of iron oxides. It has a heat capacity far above that of normal brick and is used in electric heat storage systems. The heat capacity may be in excess of what was listed on Wikipedia, I did some digging in hopes of finding the exact composition only to find that some research projects on this material indicated an even greater heat capacity than the official numbers. And its volumetric heat capacity is staggering.

yboris 4y ago

Related: rocket mass heater "A rocket mass heater (RMH), also known as rocket stove mass heater, is a form of slow-release radiant heating system, designed to primarily heat people and secondarily to warm areas in line of sight around it." https://en.wikipedia.org/wiki/Rocket_mass_heater https://en.wikipedia.org/wiki/Rocket_mass_heater

hedora 4y ago

I imagine this design working well up north, where temperatures are low, but don’t move much within a 24 hour window. We have a passively heated house, and use a standard modern wood stove. It has some stones inside it to hold a bit of heat, but only stays warm for about an hour after the fire is out. It is >80% efficient and has similar emissions to these. They run $1-2K in the US. Here are some examples: https://www.blazeking.com/product-category/wood/ https://www.blazeking.com/product-category/wood/ (These tend to be heavily regulated with different manufacturers in each country producing similar stoves.) It has a built in thermostat/oxygen regulator, and can run for up to 24 hours without reloading (8-12 hours is more realistic; they advertise 40 hours on bigger models). Instead of using exterior air through an inlet, it pulls air from the house. The outside of the stove looks traditional, but is actually a cleverly designed convection heatsink, so it doesn’t need a blower. (For tiny homes or trailers, you still need an inlet from the outside.) Anyway, for modern construction at mid to low latitudes, I think this approach is much better than a masonry stove. In particular, we can turn the stove down in the morning, and up in the evening by turning a knob. We had a masonry-style stove where I grew up, and it was fine. That house was older (and shaded by trees), so it didn’t really passively heat during the day. That’s an appropriate use case for big masonry thermal masses.

sneak 4y ago

Reminder: it is extremely bad for your health and the health of those around you to burn wood and release woodsmoke, even up/out of a chimney. https://www.samharris.org/blog/the-fireplace-delusion https://www.samharris.org/blog/the-fireplace-delusion It smells nice but it is damaging your heart and lungs and those of people within a quarter mile radius.

gjsman-1000 4y ago
The truth is always more nuanced in reality. 1. He wrote that in 2012, citing a study from 2007. Standards for wood stoves have changed. Old wood stoves and open fireplaces are unquestionably dirty - in the 30-50 grams of particulate released per hour, sometimes more. But is it fair to compare them to, say, modern EPA standards which have a 2.5 gram limit per hour which took effect in 2015, or the 4.5 gram limit from 2012? I don't believe so. Sure, if you still have that ancient 80s wood stove still in your house, it's unquestionably far more dangerous than a modern product. The masonry heaters in this original post have been hitting 1-3 grams of particulate for over 30 years now. Some heaters managed to score less than 1 gram of particulates released in MHA EPA-certified testing in 1998, beating standards decades ahead of time. 2. "The case against burning wood is every bit as clear as the case against smoking cigarettes." This is an argument that proves too much - because the exact same arguments about "creating pollution you can't dispose of" is equally valid of cars. It's also, arguably, equally valid for when you buy unnecessary products on Amazon, or do any CO2-emitting activity. You would have to show it is a particularly unconscionable level of emissions - which, with modern efficiency meaning you can get about 20~25 fires in a modern device for the damage of a single campfire... if you are going to burn wood, I'd prefer you had a modern wood stove habit than a campfire habit.
lostlogin 4y ago
If you are smelling a fire from 1/4 mile away, someone is burning some wet wood or they have a very crappy wood burner.

Awelton 4y ago

I work for a company that (among many other things) designs and builds custom full stone masonry fireplaces. Almost all of our customers in Northern climates are heating huge mansions with two or three fireplaces and absolutely swear by them, to the point where the fireplaces are designed first and the rest of the residence is planned around them. Once you get all that thermal mass warmed up it radiates a surprisingly long time.

WalterBright 4y ago

When I watch "Alone", I'm surprised that I haven't seen anyone yet make a fireplace heater this way. They usually build something that is so inefficient it does little, or fills their shelter with smoke (poisoning them), or burns their shelter down. I'd at the very minimum put large flat rocks in the fireplace, then put them under the bed.

vl 4y ago
In the season with couples, one of them built pretty sophisticated temp shelter with fireplace, and then they built even larger shelter with larger fireplace. PS (They lost - instead of concentrating on food, they concentrate on the shelter, which was too sophisticated and took too much energy) PPS I'm also surprised that most of the contestants rarely move from bad locations. I.e. "this location is so bad, there is no good place for the shelter, and no food", but then instead of moving they just stay.
- WalterBright 4y ago
  I missed that season. Which one is it? It's pretty clear from watching it that it's set up so you'll starve no matter how good you are at hunting/foraging. Then it's all about the energy expenditure. I noticed that the bigger the shelter, the thicker the logs in it, the sooner they tap out from starvation. Me, I'd start with two trees about 10 feet apart and use them as my main posts. Lash a log between them about 7 feet up, and that is the roof ridge. Lean 1" logs against it. Voila! a decent, strong shelter with minimal energy expenditure. Next I'd build a bed a few inches off the ground, to keep it dry and so hot rocks can be pushed under it. Then I'd tap out because I don't know how to hunt or fish. One woman built a decent fireplace out of clay and rocks, but it was a bit too small.
  - vl 4y ago
    Season 4 "Alone: Lost & Found" I really liked it. It was intense and unique - one person from the pair had to hike to location using compass. So they didn’t start together. In Patagonia season one of the women built top-class camp as well and she wasn’t starving too! I disagree about that it’s setup for starvation - quite often there is single or maybe two participants that get enough food. It is surprising though that quite often they obviously don’t pay enough attention to food and just starve. Ie they would try to fish in the same spot and not get fish over and over and so on. I don’t have enough training to do that, but strategy-wise I would tap out if me trajectory was negative. Ie if I’m obviously not getting enough food or fail to have warm shelter as cold arrives, I would just tap out.

nine_k 4y ago

I wonder why it's historically not the default in a lot of places, while the default is a fireplace with half of its enclosure protruding to the outside of the building (which strikes me as insane). What could historically lead to prevalence of such a bizarre design?

jnsaff2 4y ago

I have a Tulikivi Soap Stone heat retaining ovens [0] in my home. It stores about 60kWh and releases it gradually over 24+h. The problem is that it's power is about 3kW of released heat. Which is not enough for my home. I still need to use heat pumps as my main heat source (not complaining as they are more efficient anyway). So it's a nice fireplace that retains heat and the cats really love it. But there is a tradeoff between power and efficiency so if you are looking to put one in, do the math and figure out whether it is the right solution for you. They also claim that over 90% of the burning energy goes to heating the home and only 10% is lost. Tho as mine uses inside air I suspect that as cold air is drawn in, it might be less. [0] https://www.tulikivi.com/en/Products/Fireplace_collection https://www.tulikivi.com/en/Products/Fireplace_collection

jeffrallen 4y ago

In Ticino they were called pina. They were built between rooms, so that they heated the living room and also the master bedroom.

FooBarBizBazz 4y ago

1. I haven't yet seen the Korean Ondol mentioned in this thread: https://en.m.wikipedia.org/wiki/Ondol https://en.m.wikipedia.org/wiki/Ondol 2. It would be interesting to revive the old Roman hypocaust system, with the benefit of modern rocket-stove design knowledge. 3. Going the other direction, a hyper-modern system based of full gasification, followed by clean combustion of the syngas -- something that looked more like a chemical plant than an oven -- would be interesting, if maybe not actually simple/robust enough to be a good idea. Would like to see it tried though.