10X More Efficient Heat… Anywhere! – Paul Wheaton










Great Big Ideas & Takeaways:

Heating homes with wood has been done for thousands of years, but there’s no denying the environmental impact of this practice. Unfortunately, all of those fires burning through the winter release a lot of pollution, and the designs of wood burning stoves are typically pretty inefficient to boot. You lose heat, you spend money, and pollute, and you burn a LOT of wood.

Rocket mass heaters present a clean burning alternative that’s not only kind to the environment, but burns very little fuel. But is it too good to be true? In this presentation, Paul will address the skeptics and tell you why and how these wood stoves really work.

  • Can you really heat your home with 1/10 the wood?
  • The beauty and science of the sideways fire.
  • Why chimney temperature makes all the difference.
  • Are they really any more efficient than a conventional wood stove?
  • Downsides of the rocket mass heater.
  • A beautiful, eco-friendly alternative to the conventional wood stove.
  • A safe and proven wood stove you can make yourself.

About The Speaker:

Paul Wheaton is the self-described tyrannical dictator of Permies.com, the largest permaculture forum on the web. As a certified master gardener and permaculture designer, he’s built an empire around what he calls “infecting brains with permaculture.”

His forums are full of rich information, and there are a number of great free resources, guides, and articles that can be found on his sister site, Richsoil.com as well.

Most recently, he has worked with rocket mass heater experts Ernie and Erica in developing a 4 DVD set on all things rocket science, and has built a following around his World Domination Gardening DVDs, which detail how to use hugelkultur, swales, and natural ponds to capture and utilize water without irrigation.

Crowned the Duke of Permaculture by Geoff Lawton and the Bad Boy of Permaculture by the Occupy Monsanto movement, Paul continues to educate and inspire, and regularly hosts workshops and natural building experiences at his property, dubbed Wheaton Labs, in western Montana.


QUESTION: What heat sources do you use on your property? Would you consider adding a rocket stove to the mix?




  1. Judy Stutsky

    very interesting! I was good with him focusing on counteracting the naysaying since he has the Youtubes to help you build it if interested.

  2. Bea

    Hi John, I’m a numbers person and find the statistics quite interesting BUT numbers can always be manipulated to reflect a bias. I think one of his main points is that the stove companies may use techniques to doctor their findings. It really does happen in “science” more than you might think.

    We have personally used rocket stoves outside and can therefore understand and validate the principle based on experience, not numbers.

    The title of the segment is not “building a stove” but Mr. Wheaton does provide several practical building resources closer to the end. It may benefit you to fast forward to the last couple of minutes for that very useful information.

  3. Kent

    This is an excellent presentation! The sales pitch for his DVDs only lasts a few seconds. The rest is directly useful information. Addressing the negative arguments is not a waste of time if you are actually thinking of building a rocket mass heater (RMH) . If you do not understand those arguments, you are headed toward some mistakes if you try to build an RMH. Even though the actual sales pitch only lasts a few seconds, the DVDs (and free stuff on youtube, if that is what you are after) tell you the details of building. All-in-all a very useful presentation for those that are thinking of building an RMH.

  4. Jeff Hampsten

    you should check on the melting point of steel before quoting 3000 degrees reached in any wood burning device made in some part of steel. the masonry portions of the machine would of course be ok at that temp but it is difficult if not impossible to reach temps close to 3000 degrees burning wood. A fully engulfed stick built home fire could reach 1600 degrees but not much more no matter how large or small it is. BTW mild steel melts at about 2500 to 2700 degrees depending on the amount and type of alloys. also would have been interested more in the how to build one part, the variables in how much wood you use are way to many. suffice it to say you will probably use way less and quit arguing with skeptics, if they don’t want one tell them to buy or build what they want. I’m in the process of installing a rocket mass stove in my greenhouse. 🙂

    1. paul wheaton

      When it comes to building a rocket mass heater in a greenhouse, I am compelled to make one important point: make sure you vent the exhaust outside. I have to say this because a lot of people get the idea “hey, a rocket mass heater puts out almost pure steam and CO2! Plants love steam and CO2! I’m gonna route the exhaust inside!” Ernie, Erica and I recorded an entire podcast on this topic. It is a very bad idea. The short answer is: route the exhaust outside – don’t be tempted to do anything else.

  5. Marjory WIldcraft

    Hi Jeff, whew… I don’t have the materials background to say. I hope Paul hops on here to respond.

    1. paul wheaton


      I think he is echoing some of the points made in the presentation.

  6. paul wheaton

    I’m here! I’m ready to answer questions!

    1. Marjory WIldcraft

      Hi Paul, Nice to see you online!

      I am considering a move to a more notrhten climate, and yes, a rocket mass heater would be perfect. We currently burn with a little super cute wood burning stove. It doesn’t really get that cold here.

      1. paul wheaton

        I wish to be very clear: there is no place in the world as awesome as Missoula, Montana. For people and for gardening!

  7. Vic Harris

    Droning, boring, irrelevant defence, with almost no substance. I was very interested at first, but can’t take his poorly designed “sales pitch” on a remake of another version of a Russian peasant’s stove that has been in use in Siberia for centuries.Less egotistical B.S. and more substance might help. Bottom line: talk more about your design, and less about your fragile ego. No one cares, that you have not been hailed as an innovative genius, for copying a basic, well known historic design. Less smoke, and more flame OK?

    1. paul wheaton


      I think you will find that the designs have come a long ways in the last eight years.

      The fact is that we have presented many, many times about how to build them and how efficient they were. When asked to give this presentation, it seemed that we had a gap to fill – a few people needed to have the criticism addressed. So we made this.

      Of course, it sounds like you have a great deal of knowledge to offer yourself. Perhaps you have some youtube videos about the siberian stoves?

    2. Bea

      Wow, Vic! Ease up, man. We’re all friends here. Some of these presentations have used up roughly half of the time in sales pitch (Rick Sapio) but this “pitch” was more of an aside than a pitch. And, I am pretty sure there are lots of people who do hail Mr. Wheaton as an innovative genius. Seriously, have you seen his youtube videos?

      Those basic historic designs may be well known to you but they are revolutionary to those who like me had never heard of this type of heat source until a few years ago or maybe just today.

      Be nice!

  8. Sharon Morton

    Excellent presentation! I would love to build one of these in my house and forget the natural gas. But, I am a 63 year old woman with health problems and could not do this by myself. This seems like such a great way to warm the home. Can this be used as a stove to cook on? That would also get rid of an appliance that takes up too much space.

    1. paul wheaton


      There are a lot of designs coming out now that are rocket wood cook stoves for indoor cooking. The 4-DVD set has one example in the innovators event, but here is one that is even prettier: https://www.youtube.com/watch?v=VBBUuY-c6jU

  9. Jean-Guy

    What a great and informative information .. plan to build a RMH for a future greenhouse … not possible for my present home … live the idea ..TY

  10. Brett

    This presentation was about rocket mass heater, not rocket stoves. The high temps Paul was talking about is in the insulated burn chamber and riser which are not steel. The barrel is exposed to room temp on one side, so never reaches those temps. You really need to do more research before making your critical comments. I thought the presentation was very truthful and addressed a lot of misinformation out there so people could make an informed decision.

    1. paul wheaton


      I hadn’t thought of that. I thought that guy was re-iterating what I said in the presentation.

      In DVD 4 of the new 4-DVD set, Peter van den Berg and I go into a lot of detail about the use of metal inside the rocket mass heater core and why it is a bad idea. Even at 1600 degrees F, the metal doesn’t melt, but it does spall. Therefore – avoid metal in the core. We then explore the use of perlite and vermiculite: a bit of an edge case. Firebrick wrapped in ceramic fiber and/or and moldable ceramic fiber seem to be the big winners.

  11. Jean

    Can these be installed on an existing concrete slab? The north wall of my house is on a slab about 3 feet thick which gets relatively cold in the winter, sucking up the heat several feet into the room. As I am typing I’m wondering if a modification of this type stove could be installed outside the house up against the foundation to heat it. Perhaps a porch could be added and enclosed in the winter. I don’t know what the insurance ramifications would be but “outside” might sound better from their perspective. Any wisdom or thoughts?

    1. paul wheaton

      A rocket mass heater on the slab indoors would be, I think, the best. But people have done things with the rocket mass heater outside.

      Here is a beautiful rocket mass heater built on a cement slab that was posted to youtube just a couple of days ago.


  12. Sue Young

    Thanks,Paul for your ongoing work. I loved the presentation. I’m a Permies follower and I share it with everyone possible. Anyone who tries to compare the rocket mass heater with a regular wood stove is comparing apples to oranges.

    1. paul wheaton

      Thanks for your support Sue!

  13. Brett

    Paul, yeah. So there is another myth to add to your presentation of misinformation about RMHs: that the barrel will melt. ?

    I have been a big fan of permies.com for a while too and is so much more useful with your dailyish email. Thank you for providing the free forum of information and discussion! That’s how I found out about this MEN series.

    I hope to buy property next year to start my homestead and am interested in building a batch RMH with, perhaps, a stove top. I have heated my 1700 sqft stickbuilt home with a so-called high efficiency cast iron woodstove with catalytic converter for over 10 years and burn about one and a half cords per year in zone 7 (MD). My biggest complaint is the air gets dry (RH drops as temp rises), so I run humidifiers, then it gets so cool by morning (60 F) that it condenses and everything in my house rusts. And I don’t want to get out of bed in the cold morning air to start the fire. I am going to have LOTS of thermal mass in my next home. Looking forward to getting your DVDs in a few weeks when finances allow. Thanks again for all you do for community!

    1. paul wheaton


      Thanks for all those mighty kind words! Puts a bit of wind in my sails about all this.

      I like the point that you make about how the steady heat from a rocket mass heater makes for less condensation and mold in the house.

  14. C Butt

    Good presentations minus the naked woman…..

    1. paul wheaton

      I was surprised to see the naked woman in there. I recorded the words and Destiny, my assistant, put the image in there. The image is actually a product of four women: the woman in the image, the woman who took the picture (on the rocket mass heater in cooper cabin at my place), the woman who made the image in collaboration with Destiny. They are proud of the image and think it is heaps of fun. All of the men dare not touch that sort of thing or we would all be run out of town on a rail.

      1. Eden

        I was surprised too! Especially because my children were watching with me! I covered it when I realized but my three year old son says, “Why there naked woman, mama?”… I agree, other than that a good presentation, and definitely something I’m interested in looking into.

    2. Destiny

      Destiny here – I didn’t think twice about putting that image in there, I think it is just the coolest! My friend Katelin is the one pictured, and her and her family are big supporters of Permies, we actually met at a workshop at Wheaton Labs.

      The point we’re trying to make is, even stark naked, you can still be warm and comfortable, in a drafty, gappy cabin in Montana (in the dead of winter no less!).

      1. paul wheaton

        I gave you a thumbs up Destiny. I think it is a fun picture. Congratulations.

      2. Eden

        My problem was actually more with the labels of “xxx” and “r-rated”. That’s rather tasteless and unethical considering the numbers of lives destroyed by the porn industry.

      3. Marjory WIldcraft

        well the human body is a beautiful thing…

  15. Joseph Yarbrough

    Can you channel heat through a floor radiated system?

    1. paul wheaton

      Yes. This is something that has been done many times. The idea is to route the exhaust through the floor instead of through a bench.

      1. Joseph Yarbrough

        Excellent!!! I’m building in Oregon so hopefully with Portland on board, I can get Klamath Falls County to adopt. Thank you sooo much!!

      2. Debbie

        That would be my question, as I currently have a non-functioning radiant floor system. The issue seems to be with a thermostat control, but I have PEX tubing throughout the concrete slab that is my foundation under the house. Would this cut down on the weight of the system, and do you have any plans for such a RMH system, or be able to point me in the right direction? I have been looking at rocket stoves for a long time, and am glad the concept has developed to this point. Thanks!

  16. Corky

    I wish I had the skill and supplies to build these at the #noDAPL Standing Rock Sacred Stone Camp!

    1. Geoff Lawton

      Hi Corky

      I just made one in the Dead Sea Valley in Jordan out of all recycled material just got a bit of welding done for the burn chamber to chimney right angle joint and bought some vermiculite from a nursery to insulate the chimney. The ladies in the village love it no more need to by gas to cook on or kill trees to burn.
      Check it out here, its a bit funky but it works.


      Paul is one of my heroes by the way, great job Paul.

  17. paul wheaton

    I was recently asked about the standing rock thing. My position is a very different angle. If we can collectively reduce our oil consumption by 10% then the whole pipeline project is shutdown. I have been putting a lot of my effort in reducing energy usage to this end. Including rocket mass heaters.

    1. Marjory WIldcraft

      Right on Paul!

  18. Deb Miller

    Excellent and interesting presentation. I will consider a RMH for my next house, in the planning stage.

  19. Brian

    This is the first time I have heard of this. I was interested until your debate with the nonexistent critic. Teach the principles and let people decide for themselves if it works or deal with critics in the comments and spare us the debate. Debating is not a spectator sport. But I now have something to research.

  20. Fred

    I’ve been a fan and following your work for several years. Especially your appearances on TSP. What are your thoughts on relocating from the Desert of AZ to the Desert of Washington State? (job stuff)
    Thanks Again,

    1. paul wheaton


      I suspect that this is just stupid, but I would suggest getting a different job. 🙂

      I would like to put a strong emphasis on residual income streams. Once you have enough coming in from residual income streams, you can effectively retire and live anywhere you want. A woman came to my house about a month ago. She heard my podcast about residual income streams a few years ago and is now traveling the us, living on that income.

  21. Keresztesi Wolfgang

    We heat with a wood gas system with inverted combustion that has an efficiency of max. 92% burning at 1200°C. This means that the average efficiency including starting the fire might drop to about 80%. This leaves ideally 20% for improvement or 8% at max. temperature.
    The efficiency is in relation to kgs of dry wood (calories -no matter what wood and what dimension). Sticks burn faster but produce the same amount of calories -you can’t increase the amount of calories by splitting your wood (abracadabra).
    I have no naked women to sell my logic, but even if you add some 10% loss in the storage tank and pipes of the central heating (according to their insulation this varies) -theese seem to be the physical parameters.

  22. Ladislav

    Interesting and very informative. Shame you had to spoil the experience with the carbon dioxide crap. I wonder, is it somewhat compulsory for you guys to jump on that circus bandwagon of the global warming fraud??

    1. Destiny

      I think generally, people don’t like breathing in the smoke from other people’s chimney’s, so regardless of how you feel about carbon-caused climate change, Paul’s reference to it was more about not polluting if you don’t have to.

  23. Brett

    KW, what happens to your indoor temp when the fire goes out? How many hours per day do you need to run it? In what zone do you live and how much wood do you consume?

    1. Brett

      And what is the temp of your exhaust gases exiting the chimney?

  24. Johanna

    I’m planning to look into the rocket mass heater. I want to try it in my garage and green house I hope to build this spring. It’s easier to build the green house with an idea of how it is going to be heated. I’ve been retrofitting an old house. It is nice to design something in advance rather then trying to stick in something that was never meant to be there.

  25. Yolanda

    Paul’s personality is refreshing and straight forward. I liked it!! I learned a lot even after visiting http://www.permies.com a few times.

    We have 10 acres in Central Florida where it is dry hot with no wind in the summers and then in the winters, there are some frosts days that kills the topical fruit trees. I am trying to find/locate other “Permies” in the same vicinities to hash out some situations. Paul do you know of anyone living down this way that I may contact?

    There is only some much that I can apply down here in the far South, but thank you so much for your interesting look and approach to life and things!

    Hello Darrell from Dania Beach!!!

    1. paul wheaton

      Alexander Ojeda is the artist that did all the artwork for the permaculture playing cards. He lives in florida. Jacksonville, I think.

  26. Onecia

    Thank you for your time and expertise. Oh, and all the free info as well. Great presentation.

  27. Andie

    Right now we have a big, beautiful fireplace made of native river rock that we put a propane insert in so we didn’t freeze to death or have a heart attack while shoveling it full of wood. Do you have any examples or ideas of building a RMH and still keep existing chimney/masonry? Basically, what would you recommend for someone who already has a large, permanent heating system who would like to upgrade to a RMH.

    1. paul wheaton

      Put the rocket mass heater exhaust up the chimney.

  28. Maggie J

    Is there a size limit for the bench or mass used to store the heat? Wouldn’t it be more efficient to use outside air for the burn instead of room air?

    1. paul wheaton

      In DVD2 of the new 4-dvd set I go into a lot of detail on outside air intake. Basically, you do gain efficiency, but … there are other factors to consider. In the end, for my personal tastes, I have an outside air intake and I choose to not use it.

  29. Beth

    Would this stove be effective in a McMansion that we built ll years ago when we were oblivious to living sustainably. We have a front room with 30 foot high ceiling that is 20′ X 30′, off the side of this big front room is our bedrooms down an upstairs hall. With a large fan in the middle of this room, maybe it would distribute the heat? Don’t want to move because we have worked so hard eliminating lawn and planting garden and fruit tree guilds.

    1. paul wheaton

      One of the rocket mass heaters in DVD2 and DVD4 is in our shop. The ceiling is about 15 feet tall – so I’m not sure how fair of a comparison that is. But I do think that you would want to go with “batch box style”. And with a really big house, you might end up with more than one rocket mass heater.

  30. Linda

    Can this be installed in an older home? Mostly concerned about the weight on wood floors in a three story english mock tudor from the 1930s. Also are there people who can install it for me, ie another old lady?

    1. paul wheaton

      I have heard of people buying the dvds and giving them to their favorite handyman just to be able to get the final product.

  31. MeanJean in N. ID.

    My husband watched your session this morning and…. is now planning on incorporating a RMH in our new “home” (a shop we will live in until we build a proper home)!
    Way to go~ he is a hard sell!

    1. paul wheaton

      Hot diggity dog!

  32. Loran Godbe

    Here is an interesting super-simple, bare-bones rocket “cookstove”: http://missoula.craigslist.org/sgd/5809212632.html that I came across the other day. Looks fairly easy for someone with metal fabricating skills (that’s not me) to build.


    1. paul wheaton

      This is for camping only. Not for indoor use.

  33. V

    This was my first time listening to Paul, and I thought he was hilarious. I don’t understand the opposition to addressing criticisms of RMH–it’s just a dialogue in response to misconceptions and good for all who might also have similar misunderstandings. To each their own, I guess, but this definitely got me interested in finding out more about RMHs and sad I can’t have one in my rental. 😉

  34. Geoff Lawton

    Hi Paul

    fantastic stuff as usual and as always great presentation enthusiasm getting the message across.
    I am sure a lot people are going to thank you warmly : )

    1. paul wheaton

      Geoff! I tried to send you email a few weeks ago and never heard back. I tried to use the email you sent me a few months ago … when we talked about Willie. Maybe you could drop me a line with your new email address?

  35. Fran

    Why hasn’t anyone made one of these to look high class. Good enough to put in mansion instead of looking like a home out of a horror movie.

    1. Sherri Vavricka

      People who live in mansions are not “typically” concerned with carbon footprints or cost of heat. They also generally do not heat their mansions with wood stoves. I haven’t really seen any mansion worthy wood stoves on the market. Not trashing your horror movie comment, but the one Paul showed in his home with the wood and stainless steel barrel looked pretty nice to me. Now I don’t personally like mansions, but one persons trash is another’s treasure right?! Just sayin

      1. Sherri

        Sorry before you class me with a shack dwelling horror movie fan, I will share we have about $500k free and clear tied up in our 2.5 acre homesite that resides in our smaller 80 acre farm. The investment in our other two home sites on the property do not have this substantial an investment. The $10k back up generator we installed may not be needed after all.

    2. Brett

      They have. Take a look at the link Paul provided above for the cook stove. Just omit the cook top and run the brick to the ceiling and you have a fireplace with a door, sort of like a built-in wood stove.

  36. Sherri Vavricka

    We will be building one. I will be sharing this with my dad and we will be building one at my parents farm too. He has been wanting to do heat his floors since he remodeled his city home in Houston 35 yrs ago. He is going to love this! I think I am more excited for him. We are about to build a new house on our 80 acres and this is perfect timing!! Thanks

  37. Sandra P. Gann

    I am just exploring this. I am sure since there are other sources that cover the positives and how to aspects that this was meant for people who already have a fairly good knowledge of options to heating efficiently in survival or off grid homestead situations BUT for novice and searchers this was a bit too much like a pro-con defense NOT a how to……I learned and the information will cause me to access the other information available on this form of heating….but I feel that as a novice I was bombarded with a defense of this system instead of an actual “how to “.

    1. paul wheaton

      We have 8-DVDs full of “how to”. We have oodles of youtube videos showing lots of different angles. What we were missing was something to address criticism.

  38. Sander Krijnen

    Hi Paul,

    Is it possible to place the exaust tubes in the floor instead of on top of the floor?

    Regards, Sander

  39. tuffy

    we have a 1950’s ‘post and pier’ wood floored house (a small 900 sq ft one). i assume this type of heater won’t work on this type of flooring and raised house?

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