how is a rocket mass heater so efficient?

A rocket mass heater claims to heat a home with one tenth the wood of a conventional wood stove. HOW is that possible? Let's start by looking at the label on conventional wood stove. This label is allowed to have 16 extra percentage points to compensate for some of the heat that goes up the chimney. So a wood stove that says it is 75% efficient, is actually 59% efficient.
Different testing facilities compete to measure the efficiency of a wood stove, so they work hard to produce numbers better than their competitors. Legitimately. They might use especially dry wood, or there could be a little extra air pressure in a test lab - things that could plausibly happen in an optimal home scenario. So the resulting numbers are higher than if their competitor had done the same test and yet still fall within a space of being legit.
But this means that most people using a 59% efficient wood stove will probably operate it at 20% efficiency on average. And most people putting a big green log on just before bed with dampers set low might be getting less than 3% efficiency. And when the fire is down to just embers, the stove might continue to pull heat out of the house, resulting in negative efficiency.
It is pretty easy for a rocket mass heater to compete with 3% efficiency. And even easier to compete with negative efficiency.
When using a conventional wood stove properly, the law requires an exit temperature of at least 350 degrees. 350 to 600 degrees is the most common. No matter how efficient the burn is, that's a LOT of heat going outside.
Rocket mass heaters typically test at 93% efficiency. That is without adding the 16% for going up the chimney. And the exhaust temperature tends to be 70 to 140 degrees. Since the mass holds the heat through the night after an efficient burn, people are not attempting to set up an inefficient burn through the night.
Most people shifting from conventional wood stoves to rocket mass heaters report heating their homes with one tenth the wood. Some people have shifted from modern, super efficient wood stoves that they were using very wisely - and those people report heating with 75% to 80% less wood.
Heat your home with one tenth the wood, one hundredth the smoke and wake up to a warm home.
Safer, cheaper, cleaner, easier and more luxuriant than a conventional wood stove.
Safer, cheaper, cleaner and better for the environment than natural gas or electric heat.
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[@CairnOfDunnCroftPermaculture]

For us, that 10% of the fuel of a conventional wood stove statistic has been wildly inaccurate. Our mass heater has been significantly better than that! Our house is a 1930's concrete block built cottage. No cavity insulation, no damp proof course, extremely draughty. The front door in right in the lounge, and we can see light around the door from the cracks. For three winters we were uncomfortable. No matter how much fuel we used on the open fire, we were always cold. We used coal and logs. With the fire in all day we'd easily go through £5 of coal, and £4 of wood per day, and still be cold. We'd be huddled under blankets, we'd sleep in three layers and wool hats, and still wake up cold. The mass heater uses roughly £1 worth of wood per day. That in itself is a massive saving of course, and got us away from having to burn coal, an extremely dirty fuel, but the house is actually warm now. Even in deep cold, with high winds, we can see the cold wind blowing the door curtain inwards, and remain warm. Yep, with wind actually blowing through our living space, we're comfortable. It's impossible to express just how much of a difference it's made to our lives during Scottish winters. No more rationing fuel use. No more screaming at our teenager to shut the door quickly. No more worry about the rising costs of power, propane, or coal. We have a lot of willow coppice planted, to be fuel independent within a few years, but even having to purchase logs it's so cheap we have a policy of running it whenever anyone feels even slightly cool. This year, adding a porch to the front of the house to act as an airlock should significantly cut fuel use further, and in the longer term a passive solar retrofit is planned, but I'm not expecting anything to compare with the mass heater in terms of improvements in household efficiency. The mass heater has been transformative. It is a truly remarkable technology.

[@priestesslucy3299]

This is such a powerful testimony about the value of this tech. Would be amazing to hear it expressed verbally and be able to share said video ♥️

[@CairnOfDunnCroftPermaculture]

@@priestesslucy3299 We videoed the build, with a couple more videos to add to the playlist as they're finished. I also plan a first winter review video, once it's finished enough to look pretty. kzbin.info/aero/PLmjYEOcdi0m6_eqFUzaAhhoKExXDKoytY

[@priestesslucy3299]

@@CairnOfDunnCroftPermaculture very cool, thanks for the link.

[@Handmemoretramadol]

Did you build it yourselves and does it have a significant amount of mass ie does it fill your room ? I’m hoping to install one this summer your comment really cheers me up because we’re frozen at the moment

[@CairnOfDunnCroftPermaculture]

@@Handmemoretramadol yep, I built it myself. It's a pretty big thing, but it replaces a sofa so doesn't take up much more room. The mass is oversized really, because I wanted at least ten inches of mass surrounding the pipes on all sides. Most people go with quite a bit less mass, happily. I used the Wisner book to build it, I'd not attempt one without it. I understand Paul has a mass heater book in the pipeline too at some point, but if you haven't got a copy I highly recommend the Wisner book. Our channel has a full build series of videos, but KZbin isn't a great source of information on mass heaters. There are too many people claiming to have invented the newest, groundbreaking design, and making all kinds of dubious claims after running it for just a week. Others are just badly built, or downright dangerous. Mine has been built by the book, literally, but it's still no substitute for reading the book.

[@davepennington3573]

High efficiency saves time on chopping wood. With the rising price of energy this type of information will become more popular.

[@priestesslucy3299]

Also saves wood resources. A 90% reduction in wood means the same woodlot can heat ten times as many homes. Or a homestead could comfortably reduce the size of the woodlot they plan by a lot.

[@Patricio24601]

Paul Wheaton, you are a heating superhero.

[@jeffh8322]

Yay more nice videos like these Paul! Keep up the good work!

[@CairnOfDunnCroftPermaculture]

A benefit of mass heaters I've never seen expressed elsewhere is just not needing radiators! How often do you want to put a piece of furniture somewhere, but can't, because the radiator is mounted on that wall? It's even worse in a house you buy, because the radiators are always in places you wouldn't have chosen because it would be a great spot for a bookcase, or sofa.

[@aureas]

The space a radiator might take up is MORE than made up for by the huge area the cob bench takes up, however. 😏 Even an entire wall sometimes-- or more! ...so I'm not sure I see your point about the radiator... 🤔 🤷🏻‍♀️

[@CairnOfDunnCroftPermaculture]

@@aureas the mass bench replaces a sofa, so doesn't really take up any space. It's not dead space, like radiators are. But the point I'm making is that radiators typically take up five or six feet of wall space in every room in the house. The mass bench is generally confined to the main living area. At worst, the mass bench restricts where you can place furniture in one room only, leaving you with complete freedom in the rest of the house. I hope that makes sense!

[@brucea550]

@@CairnOfDunnCroftPermaculture I agree with your assessment of the space trade off. The potential problem with one mass in one room, is how to get that heat to all the other rooms? If you have a square house/ single story/ open design and put the rmh in the center (like Europeans build the house around a central masonry heater) that would work. But when you have multiple rooms and perhaps two levels, what is the solution? That is what all those radiators do!

[@GemintheMud]

Will share. People need these straight forward explanations. Thank you.

[@CrowingHen]

I often wonder about the way the air shimmers above my chimney. I asked the chimney cleaner and he said that's normal even for a super-efficient stove like mine. That seems like an awful lot of heat going up the chimney instead of heating my house.

[@wiredforstereo]

You have to have that heat to power the draft up your chimney, otherwise your stove doesn't work. Same sort of reason wind turbines have a maximum theoretical efficiency of 43%, the air has to go somewhere, you can't just bring it to a complete stop and extract all the energy from it. Also similar reason to why all those amazing stories you've heard of about efficient car engines are bogus. Physics!

[@ellenorbjornsdottir1166]

I wonder if the exhaust system could be further lengthened in exchange for an electric scavenge fan.

[@Fulcrum205]

You could try to extract more heat with something like a water jacket or even extract electricity with peltier generators. Cooling the air will reduce the draft which will reduce the overall efficiency of your heater. You can gain it back with a taller chimney but there is a practical limit as to how tall you can go.

[@retireddac]

We love our rocket mass heater. My sister and I built for almost nothing and it is SOOO good at warming sore muscles as needed. Laying on a 7’ heated couch in the winter months is life changing.

[@trickynik12]

These will be the choice of fire of the future.

[@250tegra]

Hi Paul, thanks for that! Beautifully done, sir! A few years back we decided to experiment with RMH since we had four assorted Aussie wood-burners and over 8 acres of trees... But age was advancing, and we were getting through a fair bit of logging and humping of logs to keep things warm in our well-insulated double-glazed mud-brick home. The day was approaching when the arthritis was going to win. We retired over 20 years, so it was time to act, and I studied your stuff, which made sense. Back in the '60s as a young(ish) automotive engineer I had worked on car engines with a view to meeting proposed Californian legislation, and we now all know about catalytic converters, do we not? Interested to see these available for wood stoves, nowadays! Long story short, I built a dozen or so different cores, measuring the exhaust gas and correlating with the burn temperatures, used our mud brick annexe as a test site with a 'Bodge-Box' conversion of the original Aussie wood-burning cooker/stove with a brick bell on top, and compared results with measurable electric heating in the same test conditions, plus our records of heating with the original cooker thing in previous years. At that time (years ago), we were expecting about 4x efficiency vs the old iron stove, but my figures were off, obviously, since I was getting 9x! So good to see that our results are similar to yours! We just used Vermiculite slabs and a few fire bricks to confine and insulate our 'bodge box' inside the cooker where everything would burn, and used cunning vortex generation to do the mixing into a vanilla ceramic wool roll-up rug divergent heat riser that discharged into the 'bodged-brick-bell' sitting on top of the cooker. A proper lash-up, but it demonstrably worked. We are back in the UK now, had to downsize, no longer have any acreage or the ability to lug logs, so have been investigating the 'heat log' industry, which packs unwanted sawdust until it stays solid, and dry it thoroughly. Seems to burn OK, very low residue, and the industrial alternative seems to be to let the sawdust rot (Oxides of Carbon as well as microbial flatulence emerges) . . . or just burn it! Any thoughts on this, please? Our came-with-the-house wood stove is startlingly technical, with independantly adjustable primary and secondary air, with a fixed tertiary air feed. If I price it up, heating with these sawdust logs is certified to cost a LOT less than gas or electricity... Ben

[@pugguk]

Excellent. Sharing right away!

[@shanengivone3973]

I would like a rocket mass heater in the garage that I'm converting to live in. It has a cement floor. Is anyone experienced in building these near northeast Oklahoma/southwest Missouri? Please let me know! I bought the instructions on line, but it's too confusing and intimidating for me to attempt alone. Thank you.

[@candacewilliams6869]

Go to permies.com. There is a lot of fee info there to help you!!

[@wiredforstereo]

I've built one on a concrete floor. It acts as extra heat storage.

[@tylerblack3508]

Hey! I live in Tulsa. Do you want a hand building your rocket mass heater?

[@shanengivone3973]

@@tylerblack3508That is so sweet of you to offer!!! He ave you built one before?

[@250tegra]

@@shanengivone3973 - understand the reluctance to go for it without previous experience - we felt that, and built a series of 'unsuitable brick-based test cores' that could all be made to work by doing what Paul Wheaton and others have said online. Ours was just a vertical 'found bricks' chimney with a crude brick hearth at the bottom, built on an old concrete slab on our property, at first. Asymmetric vortex generators, double burn zones, tried all sorts... Huge fun! Pretty much free, too. #1 only took ten minutes to build (after finding enough bricks) and ten minutes later we were looking at a clean odour-free exhaust from a bunch of burning eucalypt twigs. We built a real variety of test cores this way, and learned much from the experience, Recommend having a couple of IR thermometers and at least one cheap CO meter to verify the burn quality. Buying a length of 'superwool' for the heat riser let us use it as a liner for a length of scrap steel pipe, works very well indeed. Costly but worth it imho. Good luck! 🔥👩‍🚒🔥

[@robandrachelpoulin5001]

Has there been any experiments using this type of heater with a PCM (Phase change material) to reduce the size/weight of the "mass" heat storage part? I had heard of one company (quite a while) ago that was experimenting with a wood stove that included a jacketed space with PCM for releasing heat after the fire was out. Has anyone placed external fins on the outer surface of the exposed barrel to increase the heat transfer to the surrounding air and reduce the external temp of the barrel? Has anyone tried a coil around the pipes in the exhaust duct in the thermal mass to heat domestic hot water? (occasionally circulating water through the coils and return the water to an insulated hot water tank).

[@harrymills2770]

The government-approved wood stoves are very efficient-burning, nowadays. But they don't incorporate much/any heat-mass storage. I think any efficient-burning stove that incorporates a heat mass to max effect possible is going to approach the rocket stove method in efficiency. Another thing you can do is burn outside air. Another alternative is to have the stove breathe the room air, but instead of drawing fresh air thru cracks in the house, make it easier for fresh air to enter the space where you want it to: Over the heated surface of the stove, or using a double-walled chimney. Many manufacturers make stoves with double-walled chimneys that burn the outside air and keep the living space "sealed." I think that's dumb. You WANT fresh air coming in. You just want it heated up before it enters the space. Just using the natural draw of the stove to drive the movement of air into the space makes an entirely off-grid way to move warm air into the home, in addition to the heat mass and of course the radiant heat coming off whatever stove you decide to use.

[@mdocod]

A 600lb soapstone/iron stove has about the same thermal mass as a ton of cob. Heated to 500F it stores the same amount of usable thermal energy as 12,000lbs of cob heated to 100F. Outside air kits on wood stoves are a separate thing from the stove pipe in most cases. The "return air double wall" system you're probably talking about is a pellet stove system. For wood stoves, we just use a separate 3-4" pipe from outside to the air supply on the back of the stove that feeds all the air inlets. Pulling in cold outside air directly to the firebox is the best way to do it, as the stove can then be adjusted to overcome the BTU loss from cold induction air by simply burning at a higher rate. This means the stove does not loose any effective BTU output capability in colder weather. If you let the stove breath already-heated air, then the BTU's must be transferred through the stove jacket to the air to overcome the BTU losses of cold aitr being sucked into the living space. This reduces the effective maximum BTU that can be had from the stove. Don't do it this way!

[@mikewurlitzer5217]

That is some very interesting information. I have a fairly large "Hearthstone" {I believe was the Mfg} soapstone stove that never IMO provided enough heat and certainly not enough overnight heat without 2 or 3 reloads. I admit to never really running it that hot [500F]. Were it not for the wife unfriendly appearance of a RMH, I would have chucked the soapstone stove years ago. @@mdocod

[@brucea550]

@@mdocod The hottest fire is the most efficient for burning the wood gasses. Cold outside air needs to be preheated by the stove BEFORE it is introduced to the fire or you are losing efficiency vs burning inside air. Burning at a higher rate, as you say is needed, is just confirming that loss of efficiency.

[@mdocod]

​@@brucea550 If you're trying to get the stove to run at the lowest possible output efficiently, then yes, pulling already warm air in from the house will allow you to run the stove at lower burn rates with good combustion efficiency as it will "support" secondary and/or tertiary combustion at lower throttle positions. ' At high burn rates, the fact that the air entering the stove is cold is irrelevant because the combustion rate and firebox temps are so much higher to begin with that we're not talking about whether there's enough heat to drive secondary combustion, we're way past that point. You can only pull so many BTU's through the walls of the stove. Better to consume those BTU's inside the walls of the stove rather than have to pass them through the stove walls to make up for the cold air that was pulled into the house instead. Either way you still have to heat that air up to have the same effective BTU in the house. If you're pulling cold air into the house, then those BTU's to re-heat that air are still lost, but now you have no way to overcome that BTU loss but through the envelope of the stove wall, which absolutely will be the bottleneck in this situation. By performing that heating of the combustion air inside the firebox, you can now actually use all the BTU's available to heat the house, and not lose heating headroom to the combustion air.

[@brucea550]

@@mdocod That may be true for a poorly designed woodstove but it’s not true for the rmh due to the design, which I think you’re not familiar with. The burn chamber and riser are already insulated (unlike any woodstove I’m aware of) to extract as much heat as possible for complete combustion. Introducing cold air runs exactly contrary to that design. Thus the p-channel to preheat even room temperature air for the secondary burn. And it has nothing to do with trying to run at the lowest possible burn, but again, exactly the opposite. And even if that were not the case, a house needs fresh air exchange anyway, so why not burn the existing stale air instead of drawing in fresh cold air for both stove and house, and having to heat BOTH? That is far more BTUs needed.

[@jasont6287]

Russia and the nordic countries have used this system for hundrends of years using thermal mass heating maybe not using the double burn of modern systems to burn the exhaust gas and particles but still been done.

[@trampledbygeese]

I like the snowflake animation.

[@scottkleyla7752]

I turn mixes with a roto-tiller.

[@teresacrum161]

I first heard about this type of build as a Siberian fire stove 20 yrs ago. Is there any correlation?

[@Leeofthestorm]

The Siberian stoves that you are talking about are probably what are generally known as masonry heaters. They go by various names throughout Northern Europe and across Asia. The prime correlation is that they use a mass to absorb a lot of the heat so it stays in the house rather than up the chimney and it radiates slowly. Many of these stoves burn at a very hot rate, but not generally as hot as a rocket stove, but not all designs are super hot in relation. Some big differences are that those Siberian stoves are complicated to build, and they are both huge and heavy.

[@sillydog70]

Hey guys with all the new interest in Sand batteries would a rocket mass heater using a sand battery be extremely effective heat source?

[@nateross14]

I've been pondering of an easy way to make a quick and simple RMH using cinder blocks with square holes, that anyone could build in a pinch. I was thinking you could just put a bunch of cinder blocks together so the sqaure holes make two horizontal long tubes so that the exhaust gases draft through the bottom set of square tube holes until they reach the end, and then you cap the end block by removing the inner block partition of the end block and covering the end holes with cement backer board or a pile of rammed dirt. This would turn the end cap block into a square elbow that would divert the exhaust into the upper half square tube holes and back toward the burn chamber and eventually exhaust exit point. As far as the burn chamber, why not just use a simple rocket stove design by just cutting a block in half and also cutting off one side of the block, then putting it against the entrance of the bottom block sqaure tube tunnel. This would be an all thermal mass design with no immediate quick heat, but long lasting slow release heat. I think this could work, going to try it.

[@paulwheaton]

In the rmh riser we are chooting for temps pushing 2000 degrees F. Your cinder block will spall at 600 degrees F. Easy is awesome! But it needs to also work!

[@250tegra]

@@paulwheaton & nateross- can confirm this, since (in my ignorance) our first test rigs were built with 'found' cubical blocks that had 'rounded square' holes - bringing the heat up slowly, coating them with a refractory slip, repairing the cracked ones, it all kinda worked (rocket roar, clean exhaust, unmeasurable CO exceptional efficiency) so long as long term reliability was not a concern! What did the job properly was a 'superwool' sleeve in an oversize steel tube... Remarkable material, that superwool! Ben

[@mathization]

Once a fire and its smoke go out, how can the heat in the thermal mass be prevented from going up the chimney? I can imagine a restriction in a output pipe to let any residual gasses out. Also, maybe a two pipe / valve system can be created....once the fire goes low or out, vent any fumes up a separate , chimney while not venting thermal mass heat out. I'm guessing at all this, but maybe its a nice consideration.

[@paulwheaton]

Plug the wood feed.

[@rubygray7749]

Put a close fitting cover over the wood feed in box. No cold air can get in, no hot air can get out.

[@mathization]

@@paulwheaton ty

[@mathization]

@@rubygray7749 ty

[@CC-iq2pe]

Is it a good idea to close off the exhaust on a Rocket Mass heater 15 mins after a burn is finished; will it help contain the heat inside the home without the CO2?

[@paulwheaton]

cover that in better wood heat woodheat.net

[@Nilafila76]

Can't argue with that!

[@mervynshute880]

very inspirational. shame that there is-no up to date plans readily available for a batch box hot water and cooking appliance. going to be a long wait i suppose!

[@brucea550]

Look up Walker stoves. Matt Walker has what you need.

[@bennielamb8911]

Truth

[@Catrik]

If this is true - I'm not saying it wouldn't be - why are RMH's not commonly sold and installed commercially? Is is something to do with safety or liability?

[@paulwheaton]

Rocket mass heaters are safer. Less potential for liability. There is a commercial offering - the liberator rocket mass heater. As for "commonly" - i suspect it is because nobody makes big money from them.

[@Catrik]

@@paulwheaton Can you elaborate on the "big money"? Like you said, companies are competing hard with efficiency - on top of that, safety is a big deal. So to me, it seems like there would be huge market potential with very little downsides.

[@paulwheaton]

@@Catrik I agree with your analysis.

[@randalmoroski1184]

Can something be done to substitute for the ugly barrel look…?

[@paulwheaton]

permies.com/w/beautiful-rocket-mass-heaters kzbin.info/www/bejne/iaKVqmNqmr50nsk

[@BitcoinOutLoud]

Let's gooooooooooooooooooooooooooooooo!

[@mb19842002]

Wake up with more wood in the morning

[@joubear100]

I live in Catalonia, Spain where the temps are really hot most of the time but our short winters are bitter- especially in our uninsulated, reformed campo casita! I have recently acquired the cast iron bits of a masonry stove ie an oven door, firebox, top plate.Is there anything out there to help me use RM tech to build it? Ideally I'd like to attach a water heatrer too, but would be happy to start with a simple build.

[@writer89]

But how do you sell ypur dandelions? How to price them? Do you make tea? Do you just sell the leaves or flowers too?

[@paulwheaton]

Different video?

[@wobdeehomestead]

Lol I guess I’ve been freezing all these years using my inefficient wood stove as my primary heat source!

[@brucea550]

I live where it’s cold, like occasionally -40° cold. A lot of people heat with wood, and I don’t know anyone still using a crappy Franklin style stove. That’s ridiculous. We typically heat for 7 months of the year, and sometimes 8, but 6 months round the clock at a bare minimum. We like a 70° house. Working outside in the cold does that to people! It takes a certain amount of BTUs to heat a house, no matter how efficient the burn or how much thermal mass. We do a lot of in-floor heat in this area, which is the most efficient distribution system, combining mass with heat underfoot. Almost all new construction has heated slabs. Our house doesn’t, but we have an epa style (secondary burn tubes) stove and maintain 1600+ sf at 70° on 4 cords of birch per year. Even 1/5 of that, 8/10ths of a cord, works out to about 75,000 BTUs per day. That’s how many BTUs a typical house this size needs PER HOUR at 0°F. I simply can’t see even a 90% efficient burn and cob mass being able to heat for 24 hours on one hours worth of wood.

[@wobdeehomestead]

Even if the RMH was 100% efficient there are only so many BTUs in wood. A few pounds of wood isn’t enough to heat my cabin on a cold day and keep up with the heat loss.

[@brucea550]

@@wobdeehomestead In our case, it would work out to two pieces of wood 5” diameter 16” long per day, based on what Wheaton is claiming. There’s just no way! I think they could promote this idea better if they built an actual test place, and had both a modern efficient woodstove and an rmh in it, and ran each for a couple weeks at a time under similar outside temperatures. Measure the wood by weight. Actual somewhat scientific results.

[@wobdeehomestead]

Agreed. I’m not trying to poo poo the RMH. I like the idea but I think it needs major testing and a UL approval so these things can be insured. All this will take big $ so i don’t know if it will happen anytime soon?

[@brucea550]

@@wobdeehomestead I can’t see anything built this way getting UL approval. There’s simply no quality control or consistency. That certainly doesn’t mean it’s not a great thing, just how the certification process works. I love the concept, much like Russian fireplace heaters. It’s clearly better than just a woodstove, but maybe 50% better. Here’s a video I just found, I don’t know where they live or the size or energy efficiency of their house, but they used almost as much wood in 3 months as I do. It’s a great honest review of an RMH. kzbin.info/www/bejne/eaCylKanZpeIoac

[@Nature_Quixote]

😊🌲🌲🌲🌳🌳🌳🌱🌱🌱🌻🌻🌻🌼🌼🌼🌻🌻🌻🌱🌱🌱🌳🌳🌳🌲🌲🌲😊

[@solonwilliams8349]

Okay if you want your rocket mass to be more efficient first of all if you draw an air from the outside then it would be 93% but if you're drawing are from the inside of your house you're about 45% efficient cuz you're pulling cold air through your doors and your windows I have a design for one that I don't use metal in it I use bricks and it will produce hundreds of voltage of electricity on top of heat it was also produce a lot of energy to 2 stainless steel coils that will heat up and draw water through thermal cycling

[@beaumdavidson]

rocket mass heaters, demystified with style.

[@JayBob510]

This will be my fourth full winter using a rocket mass heater for my lower floor to supplement my propane furnace. It helped cut my cost easily in half. I use a bit more wood than i first thought but far less than i would with a wood stove. I removed the barrel after three years burning. Zero creasole and only ash to clean out. I have found far more upside than downside.

[@brucea550]

“I use a bit more wood than i first thought but far less than i would with a wood stove.” I’m curious what your basis is for that claim? What experience do you have with modern high efficiency wood stoves?

[@JayBob510]

@@brucea550 I grew up with a wood stove. Plus we dealt with creasole buildup and chimney fires. I have had no issue with that. But I do not agree with the tenth amount. I find i use at least half the wood. But if you want to start a fire and walk away, rocket mass is not going to work for you, imo.

[@brucea550]

@@JayBob510 I’m curious because the 1/10 claim keeps talking about how inefficient a woodstove is, and I think this guy Paul hasn’t seen a woodstove in 30 years because the newer ones are very efficient and burn clean. I realize the rmh is even more efficient and cleaner burning maybe, but 1/10 is ridiculous. They had a competition in Washington DC a few years ago and two different woodstoves ran comparable to the rmh. So far I’ve only found one person who is heating the same space with an rmh as they were with a relatively modern woodstove, and they said it’s not significantly less wood overall. So I keep asking to try to get a more accurate picture than the people promoting rmh give. Thanks for the reply!

[@lowkeyusa]

Rocket Mass Heaters are the future

[@wulfclaw4921]

After building 2 of these and knowing how they work. I can say this is lijely the best way ever to heat. They burn clean, they use far less wood, and best of all- the disperse the heat throughout the night into the next day ! Awesome !!!

[@inventar1]

Well explained !

[@s4samantha]

Come support the Kickstarter! www.kickstarter.com/projects/paulwheaton/free-heat

[@leightate7491]

Very interesting. I've looked for information on woodstove efficiency before and had trouble finding it. Thank you for a great video with the stats and explanations.

[@mdocod]

Modern wood stoves when fitted with blowers achieve 70-80% efficiency while burning pretty clean. Some with catalyst combustion can provide extended burn cycles of 10-20 hours or longer depending on the stove size, combustion regulation tech, and fuel type used.

[@healthygreenbrave]

I love the round door in this video, Paul!! It makes me want an RMH just so I can be more like a hobbit. 😊

[@juliam3980]

This technology is so pertinent today, with the cold wave we are having all over the midwest and west.

[@higheriam]

Cool video...

[@sillydog70]

Hell, just a woodstove, a regular woodstove with a sand battery build around it could greatly increase the efficiency of heat, long-term

[@ellenorbjornsdottir1166]

I'm going to treat this as a quiz, and answer as such (based on what I have learned from a tonne of duckduckgo) before I get your take. Burning far hotter (so releasing more heat from the same fuel), and through the long exhaust system, exchanging more of the released heat with the mass (basically a storage heater made of cob, gravel, or any other suitable medium, rather than the air known from electric storage heaters) rather than with the outside air (where it just contributes, along with the released CO2, to global warming) so you don't have to run the fire as long for the house to still be warm when you get back out of bed, and less overheating when you actually fire.

[@Xenotork]

Lizards knew what they were doing when they found a hot rock. It just took us a couple hundred years to start popularizing the human version.

[@brucea550]

This is not a new idea, just a different version. China and Europe have been heating mass for centuries.

[@offthemap9582]

Are there ready made complete unit rocket mass heaters on the market that can be easily installed?

[@candacewilliams6869]

Yes and selling well.

[@250tegra]

@offthemap9582 - yes, in the US a brand called 'Liberator' - kzbin.info/www/bejne/eKLLoIOJeLJ6aq8 and in Europe a maker called 'Gamera' - www.youtube.com/@RocketHeaterGamera HTH!😁

[@brucea550]

No. They need to be built in place. The Liberator is not a rocket mass heater.

[@infinidimensionalinfinitie5021]

liked, already subscribed, craving to participate, know how i want to participate, but find i'm more effective following this deviant path. aaagggghhhh.

[@davidlampe4153]

I saw a video on rocket stoves from someone in England he setup a small J rocket stove that had a stirling engine which he suggested that with some magnets and winding’s he could generate some electrical power. Have you gone down that rabbit hole yet?

[@wiredforstereo]

My mass is a bit too small for my stove, thus my tested efficiency is more in the 70% range. But I still heat a 3700 square foot two story house with it, with only a couple cords of wood per winter.

[@sillydog70]

I don’t see why and all metal woodstove couldn’t have a giant sand battery put around it and have a chimney just vent out the top of the sand battery generating heat for a house or multiple houses for a long time or at least hot water

[@brucea550]

It’s available, you can buy wood fired boilers that feed tubing coils buried in sand, which is insulated. It supplies heat and domestic hot water. I supplied firewood to the owner of one back in the 1980s. It heated 4000sf of rentals and all their hot water plus hot water for a livestock barn. Was a neat setup!

[@actontreadway1168]

Is there smoke outside? Seems like there'd be little to no smoke visible from the outside of the house. Would anyone be able to detect it from the outside?

[@paulwheaton]

here is a two minute video about the exhaust kzbin.info/www/bejne/oXjEeKeFbbKeh80

[@actontreadway1168]

@@paulwheaton that is impressive. I have to find a way to hook the house chimney up to my bike now

[@fiendeng]

Do any home insurance companies cover someone with a homemade rocket mass heater? Or are their companies that make regulated and tested stoves

[@aureas]

Take a look at the Liberator, from Missouri. Gamera is approved in EU but not US.

[@candacewilliams6869]

Yes there are companies which will cover. It's wood heated and some will allow that.

[@brucea550]

@@candacewilliams6869 Which insurance companies do you know for a fact will cover a homemade rocket mass heater?

[@candacewilliams6869]

Ohio Casulty is one.

[@brucea550]

@@candacewilliams6869 Thats great! So far the big names like State Farm and Allstate won’t.

[@cxsey8587]

Could you put the burner outside and run the mass inside your building? I worry about having the chimney and burner in the house. For more than one reason.

[@paulwheaton]

Been done. permies.com/t/40/5937/rocket-mass-floor-heater-finally

[@garthwunsch]

So what do we do about Canadian insurance companies who are so risk averse they don’t even want one in a plastic greenhouse?

[@myronplatte8354]

Tell them to FO

[@ellenorbjornsdottir1166]

In a plastic greenhouse, not having a fire is a wise choice because plastic produces toxic fumes when it burns. Any heat from a wood fire should be piped in from a building where it's safer. As far as insurance... if you can't get insured, depending on how much you earn and already have, put what would be your premiums, or much more, into a high-interest savings account where you can draw on it in case of an insurable event (to include having to call the fire team).

[@allfaithworks]

In theory could you make the entire floor of a room heated?

[@paulwheaton]

kzbin.info/www/bejne/bJ24dIKlrLSggJo

[@rolfnilsen6385]

The romans heated both floors and walls with wood. The hypocaust. Not very clean burning, but used to heat both villas and the baths. For the baths the fire heated not only the floors and the calidarium but also the hot water. Koreans still have a variation of this system called an ondol. (You probably know already - but your last name is a descriptive term for the bronze age "long-houses". Thought I would mention that as it fits well with the roman period)

[@allfaithworks]

@@rolfnilsen6385I'm amazed you know what our last name means. That's very thoughtful. We lived in Upper US and freezing Temps are regular 6 months of the year. Heater underground water is becoming more popular too but I have been considering something like this for my chicken coop so that electricity isn't needed at night.

[@rolfnilsen6385]

@@allfaithworks "Langhus" is still a word in use in norwegian to describe bronze age houses well into the norse age, as well as a surname and a place. So it is less impressive than it might seem :-) A woodstove connected to thermal mass is great. I heat my home with a 500kg soapstove heater where the hot gases pass through long channels before exiting. I load the 1x1x1 foot firebox three times through the day and it heats my home. As long as the combustion get enough air and there is thermal mass - the efficiency is great. If you are willing to light a fire daily in the chicken coop a rocket stove connected to thermal mass will do it. As long as the coop is insulated.

[@priestesslucy3299]

@@rolfnilsen6385 it feels impressive to us in the US with a disconnect from our heritage. It's a common, unfortunate reality here

[@artytomparis]

How do you deal with the accumulation of bitumen and naturally occurring turpentine that condenses inside the mass heater?

[@candacewilliams6869]

Reports are it burns up instead of accumulating.

[@artytomparis]

@@candacewilliams6869 I'd like to see those reports because the bitumen and turpentine condense from the cooling gasses which pass through a chimney when it's not vertical. The Japanese had a solution for this in their heated mass chimneys but it's a very specific process and they used it as a resource. If it's not being removed / harvested that's a problem waiting to happen. They are both extremely combustible.

[@myronplatte8354]

If they are both extremely combustible, I would think that if they condensed inside the tubs, they would be combusted in the next burn.

[@artytomparis]

@@myronplatte8354 That doesn't take into account their position in the horizontal chimney. For them to condense they have to have cooled enough to come out of the gas state and into the liquid. Each has a different temperature point to condense but I think it would be close to the exit area in a short chimney. The Japanese used to calculate the point based on the temperature at different areas in the chimney (not an exact science) and developed pooling and draining ducts. They didn't waste them. As long as they are harvested, they aren't dangerous but if they pool then, yes, they are very dangerous. You can see in this short video how 'pitch' is harvested from condensing wood smoke. kzbin.info/www/bejne/e4mzmmCEgamGj9E

[@wiredforstereo]

@@artytomparis Candace already told you and you ignored her. They burn up. The combustion chamber is so hot, virtually nothing survives. They are not dangerous because they are consumed.

[@hotcoffeegaming3397]

You need to do videos with times and temps with the gun like uncle mud

[@CC-iq2pe]

I would argue that electric heat, if done correctly is more environmentally friendly.

[@paulwheaton]

I think that the most environmentally friendly electric heat will still be worse than a rocket mass heater.

[@bocain812]

You can make a rmh with materials on hand (where I live). It can be fueled with fallen twigs and branches. There is zero mining involved, only time and Permies inspired ingenuity.

[@rubygray7749]

Heating the air in a house will always be the most inefficient way of trying to get warm. I've had an electric mass heater, and it was useless, expensive and noisy. Wood is the original solar battery, requiring very little to store it indefinitely, and constantly renewable. The exhaust from a rocket mass heater, pumped into an adjoining greenhouse, can insulate food plants from the winter cold, and supercharge their growth with plant food, CO2. The ashes from the fire are valuable for soil amendment. What could possibly be more environmentally friendly?

[@CairnOfDunnCroftPermaculture]

My mass heater is carbon negative. Its use sequesters soil carbon. My fuels are sourced locally, from a woodland regeneration project. Their harvesting improves biodiversity and local resilience. My heater can be repaired using materials I can literally go out to my field and dig. It has no moving parts, and requires no engineer to maintain. It uses no environmentally costly materials. It requires no outside infrastructure. No miles of cable, no huge wind turbines that cannot be recycled, no high embodied energy solar panels, no radioactive materials, no fossil fuels. It doesn't shed microplastics, or generate radioactive waste. It doesn't require a highly insulated home. It can passively cool in summer. It ventilates the home without the need for complicated heat recovery systems. It runs on sticks. It produces a little ash, and a little water vapour. That's it. Compare that to the very best electric alternatives, and I suggest it wins hands down, in every category.

[@elad352]

? electric heat, if done correctly is more environmentally friendly.? where you think the fuel to produce electricity comes from? same for electric cars, wind turbines that cannot be recycled, and we know the dangerous from nuclear power plants and all solar produced are very expensive for most people. I give the rocket mass stove a big thumbs up .