Can You Heat Your Home With Bricks and Twigs? Paul Wheaton Thinks So.

Let’s say, just for argument’s sake, that you think the world would be a better place if the collective “we” used less coal, oil, natural gas, nuclear energy and other heat-generating resources.

Or, maybe you don’t give a rip about the environment but you sure like saving money.

Perhaps you just need a reliable DIY way to heat your off-grid cabin?

Enter the Rocket Mass Heater, a “hyper-efficient wood-burning stove” (Wikipedia) and the preferred home heating solution for hip enviro-survivalist-DIY-off-grid-natural-building types since 1970.

I’m no expert, but as far as I can tell, a Rocket Stove is a way to build a massive jet-engine-type-burner (think “turkey fryer BTUs from something that looks like a coffee can”) that runs on twigs and kindling. These have the advantage of being DIY-able for nearly free if you have the right random collection of stuff hanging around.

A Rocket Mass Heater is basically one of those jet-engine-type-burners and a special exhaust tube built into a big mass of masonry-type stuff that radiates heat out into your home. (For goodness sake, don’t use my description to build one – you’ll blow something up – go get a proper plan.)

The result of mixing a jet engine that runs on twigs with a lot of masonry bricks?

Well, according to Richsoil.com, Rocket Mass Heaters have some serious advantages over conventional home heating methods:

  • Heat your home with 80% to 90% less wood
  • Exhaust is nearly pure steam and CO2 (a little smoke at the beginning)
  • Radiant heat from one fire can last for days
  • Build one in a day and half
  • Buildable for less than $20

I only partially grok the fire science behind Rocket Mass Heaters, but this photo helps to make it more clear:

Image:Richsoil.com

What makes a Rocket Mass Heater unique is the extremely well insulated chimney that gets so hot it burns off smoke and particulate and creates a strong air-flow current that results in a super-clean, nearly smoke-free burn using minimal wood.

The “Mass” in a rocket mass heater is important too – the super hot combustion chamber and the exhaust channel radiate their heat out through rocks, fire-bricks, fire-cob and the other high mass stuff that surrounds them and this radiant heat means that a small RMH fire can warm a home for days. This mass means that Rocket Mass Heaters tend to have a particular look – kinda like if a clay pizza oven and a window seat had a baby.

Which can be far more attractive than it sounds, actually. Like this:

Image: Ernie Wisner, Rocket Mass Heater super-expert

Or this:

Screen shot 2013-03-04 at 11.15.39 PMImage: Cob Cottage Publications via Amazon.com

If you are as intrigued as I was when I started learning about Rocket Mass Heaters, you can find a ton more info at the Permies.com Forum dedicated to wood burning stoves. I also like this video for a good overview on how these heaters are put together.

And if you think this crazy brick-and-twig off-grid heating system might be for you, you may want to get in on an active Kickstarter Campaign started by Paul Wheaton of Permies.com. He’s making a 4-Set DVD series on how to build Rocket Mass Heaters (and other related stuff) without blowing up your house or melting your face off. The trailer for the Kickstarter is worth a watch below if this technology interests you.

If you could learn to build one safely, would you go off-grid for your home heat with a Rocket Mass Heater?

To Do In The Northwest Edible Garden: March 2013
Whine, Wine and Weed

Comments

  1. The thing that always seems like a hurdle is that so much of this stuff seems 1) to be more suitable to new construction than an existing home and 2) a codes inspector’s nightmare. Granted I have read many of the books, but I just wonder if/how any of these rocket stoves would pass inspection. Or if you could legally sell the house – especially to a buyer looking to get a bank mortgage – with nothing for heat but a rocket mass heater.

    I live in a small house with a gas furnace in the basement. I can’t even figure out how I could make a woodstove work; I’d want it upstairs where I could keep an eye on it, but the woodstove would keep the furnace from coming on; hence, no heat downstairs which would mean frozen pipes.

    I think if we’re really going to “go green” and try, as a society, to live more sustainably, we’re going to have to figure out how to do it with our existing housing stock, most of which isn’t going to be easily adaptable to things like rocket stoves and the other more earth-friendly technologies that are sure to come along. I could be wrong, but I think it’s gonna be kinda like when they had to start figuring out how install electric wiring, telephones and indoor plumbing in early 19th century houses that were built before any of that existed.

    • Should be “Granted, I **haven’t* read many of the books”

    • I think you are totally right. As I was researching and writing this post, I kept looking around my perfectly lovely, not-very-green home and thinking, “how could I do this?”

      And the answer was, “I could sell this house and build a new one.” But once you start thinking down these kind of weird alternative directions, a whole ocean of possibilities open up, and one thing about the US is, we don’t stay still for long. There *is* turnover and deep-rebuilding and trend shifts. So, I wouldn’t rule out retrofit options.

      I also see this technology as ideal for more off-grid living. Like my quip about the off-grid cabin. If I were building one, I would DIY RMH and small-scale solar and get all the benefits of rustic modern living without the grid tie.

    • Randy Greer says:

      biorootenergy.com

    • Exactly. I’ve seen one of these stoves in an earthship in Darfield BC (http://www.darfieldearthship.com) but I think it’s taken them about 4 years to build that house (and they aren’t finished yet, but have moved in). I live in a trailer where we get -37 often enough for it to be an issue, but I live in a trailer – so I can’t build one of these yet. We live in a trailer park, with a small enough yard that removing the propane tank made a big difference, and we use wood as our primary heat (there will be no shortage of beetle-killed pine here in the near future). The trailer is what we can afford right now, partly because I still have a house in Nova Scotia that has been for sale for the better part of 5 years. I can’t see that there is anything wrong with that house, except that it has little potential for off-grid, so how can I blame someone else for not wanting to buy it? Now if I could afford to retrofit it, with something that would be OK with my insurance and mortgage companies, and be OK with a buyer’s mortgage and insurance companies, well, we’d be on to something!!

    • In vermont we don’t have code inspectors really…if your building a house with your own money no need, but if with bank money they may require it. The Rocket stove needs to be built to code for safty , this being materials, thickness and distance from combostables..also load bearing sight built on. All of the information is readily available… When selling the house it may be an issue , and may require you to tear it out. As far as your downstairs heat not comming on …it should be on a seperate zone with it’s own thermostat , it will work independantly.

  2. Lovely idea – I guess it’s a contracted form of the Roman hypocaust system, which used slightly more fuel and slaves to keep the fires going! If we were building now we might be tempted to put one in, but I can’t see us remodelling the house to put one in now. we have a ceramic stove which works well, even though it does use a lot more wood to keep going.

    • Those Romans were such good engineers. I think one of the Kickstarter vids is about using Rocket tech for water heating. It seems to me that if you could ground-up the technology, you could get room heat and hot water from this technology. Water has a huge thermal mass, so it would act in a similar way to masonry. But this is apparently the part most likely to cause your face to get blown off if you do it wrong. Which is high motivation to do it right.

  3. Here’s a topic where my passion boils over a bit. I nursed a minor obsession with rocket stoves for a couple of years and have made several of them – albeit, portable and not permanently fixed w/in a home. The stoves I made are able to boil a liter of water within about 8 minutes using a few sticks — this is dependent of the fuel type of the amount of oxygen it’s drawing.

    I believe rocket stoves will become a feature of the future. When you get them dialed in correctly, they are awesome to watch… everybody I ever fired the rocket stove with was always amazed at its performance, and I love cooking dinner for people on a rocket stove by just gathering up some sticks around the site.

    Anyway, great post as always.

    cheers,
    pat

    • “where my passion boils over a bit”
      “able to boil a liter of water within about 8 minutes using a few sticks”

      …I see what you did there. Well played, sir, well played. :D

  4. queenofstring says:

    I am in love with the mass heaters, but agree that they would be a difficult retrofit in most suburban homes. I did build a rocket stove in the yard, it’s awesome and always impressive to use. We do use it quite a bit in the summer to keep the heat outside and it’s one thing it’s not too hard to persuade the kids to tend to :-).

    • I wonder if one could build an outdoor, seasonal canning kitchen and use a rocket stove for preserving….I’m a bit skeptical on pressure canning heat control, but for BWB it should work, right?

      • I don’t know about canning but I think an outdoor rocket stove would be ideal for boiling sap. I have several mature sugar maples on my property and have thought about someday trying to tap them. However, since it takes 40 gallons of sap to make one gallon of syrup, it seems to me that you don’t necessarily want to be boiling off all that moisture in the house – but something like a rocket stove outside would be just the ticket.

  5. This is awesome, I’ve never heard of them. I hope to someday build me a quaint house with one of these guys. :)

  6. cptacek says:

    My brother built one in the old rock shed. It was warm enough to keep 4 baby calves from dieing in the last blizzard!

    But, the shed was so leaky it wasn’t enough to make it comfortable in there without coats/hats/etc. He is trying again with a Peterburg Rocket Stove (I don’t know the difference).

    Honestly, the problem with things like this is that they are not standard. If a person makes their own out of scrounged parts, and experiments and changes and starts over and tears out and reinstalls and buys longer pipe and makes their own cob and after that cob cracks tries a different configuration and…blah blah blah, then they know enough to figure out what was right, what was wrong, and what they need to do to fix it. They also will put up with a week of no heat because they are working on their passion. Others can’t fix it, because it is so custom, without going through the entire process from scratch, if they can at all.

    If a company (or a person) had a kit and a standardized way to install these, which included after sales support and guarantees, these kinds of things would be more accepted and would work their way into more homes.

  7. BWB = boiling water bath [for canning] should work, with watchful supervision. Now, Buffalo Wings and Beer, Beans With Bacon, BackWoodsBrew….well, acronym city. I play it all the time in traffic, with license plate letters. Oh, I fell off topic – I wonder if the main heater/stove could be plumbed with water lines to other parts of the house, with fan-equipped radiators. Sticks and twigs are easy to get when you live next to a national forest!

  8. We used a conventional woodstove as our sole source of heat for years. Since we moved 2.5 years, we’ve been stuck with electric. Holy crap, what a nightmare. It costs a fortune and you never really feel warm in the same way you do with wood heat. (Yes, I know that last part sounds crazy but I swear it’s true!) We were going to buy a woodstove and install it last month but life happened and the money saved for it went poof. Argh.

    Being a freaky hippie type and a DIYer, I’ve heard of rocket stoves before but, for whatever reason, it just never settled in the right spot in my brain to make me go, “YES! Let’s do this.” until today. The lightbulb finally went off. Thanks!

    Due to a gazillion other pressing projects currently underway, it might be several months or even a year before we get to it but we will. :-) Time to do some reading!

  9. We’d do it in a heartbeat – if we were building from scratch. I think they’re pretty, too, and someplace to warm your butt sounds like a really good idea. I bet you’d never get the cats off that bench though! I sure hope the day will come for kits and professional installations so the surburbanites can have theirs too.

    We installed an “Al Gore-approved” type clean burning woodstove in the basement soon after we moved into our 1920′s bungalow and we’ve spent much of the (Canadian!) winters since then with the doors and windows open, it gets so hot in here. There is nothing like wood heat, and as a bonus we can cook on it in a pinch. Oh, and when our clothes dryer died we didn’t have to replace it. Yeah, I’m a fan of the wood heat! Wood is still cheap here in Quebec but sticks are free. Sounds good to me!

    Funny, I just found your smart and sometimes fricken’ hilarious blog a few days ago, (yes, that was me lurking and reading just about the whole damn thing). Then I saw the reference to Wheaton’s Law in comments, and wondered if there was a “permie” connection here…

  10. What about building one just outside the house and ducting it in to a pre-existing forced air heat system?

  11. You said ‘grok’, ‘melt your face off’, and ‘kinda like if a clay pizza oven and a window seat had a baby’. Exhibit A in the case of why we need to be friends :o)

  12. Isn’t permies.com GREAT!! Whenever I find myself caught in the doldrums of the blogosphere or can’t catch a decent wave on the internet I skip on over there for an enjoyable and sometimes enlightening hour or so of zone-out.

  13. Once again, oh wow, more research needed here guys. Ok guys, if you’re in a code enf0rcing area what you want and can have and have excellent re-sale value is the more efficient version of a rocket mass stove which is called a masonry heater. Look here: http://www.mha-net.org/msb/ and then look at tulviki’s which you’ll need to re-mortgage your house for. The benefits are higher, significantly so, efficiency compared to a rocket stove, code compliance, EPA compliance and something that fits more conventional ideas of how to heat your house. Not that I don’t love me my rocket stove, but they’re for off-grid, no other materials builds, which I’ve done a few. If you’re in the city, masonry heaters are your option.

  14. I decided awhile ago that this is something I want to do. We have a contract on a small house that we will be able to redo to incorporate it by busting down a wall in the kitchen. Still trying to figure out the exact location to put it. Do we want the warming bench or a more traditional look. I really can’t wait to have it come together. My agent had assured me that no permits are necessary for the inside of the house, I described the project to her and she says its not a problem.
    I’ve searched the blogs and still wonder if I’d rather talk to a brick mason and see if they’d be willing to take this on. I have too many tasks and would like it done right. I did purchase the last kick starter project that I found out later is a straw concept. Wheatons project sounds interesting, but he still says that the DVDs aren’t enough for the average person to be able to build a unit inside. So now I’m stumped….. Not sure what it would take for the normal person to accomplish this.

  15. SandraH says:

    This reminds me of something similar on my grandparents farm in Switzerland. They cooked in a wood fire stove and it was connected to a seating area that was tiled in the living room. In the winter, that room was toasty warm just from the heat generated from the cooking stove.

  16. Interesting heat source…I have been heating the house (850 sq.ft.) with an air tight/free standing wood stove for 13 years….Takes up to an 18″ log and does the job nicely..However, I do go through the wood…especially if its below freezing…Love to get the seasoned oak if its cheap or free…But this year, the oak is a hard to find and I’ve found an alternate source of wood…2×4 end cuts from a truss factory…piles and piles..spread over several acres…AND..its free…Sounds like this rocket stove would be the ticket…Several years ago I was researching pyrolactic stoves (spell check says no such word)..anyway, these stoves sound a little bit similar…when they get started they burn super hot, turning the wood into a volatile gas… Basically, its heating wood without oxygen (if you heat wood to about 850 degrees, it turns into a gas)…Anyway, I like the idea of storing the heat…so much of it goes up the flue and is wasted.

  17. Melissa says:

    We currently use a soapstone wood stove to heat our home, built in 1909 it needs work, is the family homestead that basically sucks money from us whenever we have it. Our backup heat is oil, which we are still on our first tank for the winter…we don’t usually go through an entire tank of oil…I do have a dirt basement…and I think this would be awesome down there…..

    • I lived in a place in Montana that had a masonry stove, and it was incredible. It was a huge, brick stove with a relatively small firebox. We fired it as hot and fast as possible — usually just for a few minutes before it burned so hot that there was no smoke. When it reached its peak, we shut everything down and the heat dissipated through the masonry.

      It would keep our whole house warm for up to 24 hours, and our lives revolved around it in winter. I loved that thing, and would love to have another someday.

      pat

  18. Would we consider this? Sure. But like yours, our house is a “perfectly lovely, not-very-green home”. It’s a basic 60s tract home and I’m not sure how we’d seamlessly integrate a rocket stove design. (Not that I wouldn’t love a home with that aesthetic if I had a do-over.)

    What we are considering instead is a wood-burning boiler. The stove itself would be outside the house and surrounded by a a water jacket. Hot water would be piped into the house where a fan would blow over it and blow clean hot air into our home via existing furnace duct work. The hot water itself would be plumbed in as an alternative to our gas water heater. Probably less efficient than a rocket stove, but more efficient than a standard wood-burner. Not to mention, the fan system could run on solar power, battery backup or generator, so no loss off heat during a power outage.

  19. I grok you for even remembering the word ‘grok’!

  20. Been looking at these for a while now and I had a wonderful idea.
    Place the stove in a ~4x4x6 foot shed/concrete block bunker filled to the brim with cob or compacted sand or concrete with air ducting running through the mass. Insulate the snot out of the shed, turning it into a hyper-efficient colman cooler (basically) and (if one is tech-handy) use a sterling engine to run the fan to pump heating air through the mass and into the house, perhaps into the existing duct work.
    I came up with this idea when I was showing a freind about these heaters and he mentioned how to get around the boneheads with rules that will demand money for the privlige of innovation (inspectors and municipal bullys)…

    Can any of you fine folks see any issues with this plan or perhaps know of a system that has already been built like this that I can study??

    Email gratefully accepted (ruffkeeper AT yahoo.ca)
    Thanks and peace to you all…
    John.

    • I would totally suggest you run your idea past the awesome folks at the Permies Rocket Stove / Rocket Mass Forum. Erica and Ernie Wisner, the team who lead that particular forum, are the leading experts in this stuff. They or some of the other experienced Rocket Mass folks will be able to give feedback on your idea and catch any potential problems better than anyone, I think.

  21. Paul where can I buy your DVD’s. Great ideas on better living

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