portable rocket mass heater

A cast core could be made of .....  clay and perlite?  Plus something stringy to keep it from cracking .... 

A steel core is a possibility, although it would be a bit expensive.  And it could be heavy.

A cast core could be light and cheap to make - depending on the materials.

I wonder if somebody could get a cast set up and sell cores for $200 per core.  For a cast setup, the materials might cost about $20 per core.  For a steel setup, the materials might cost more than $200 per core.

The artist in me just has to ask...Is there any reason why you could not or should not do something decorative to the outside of the barrel after completion?  Could it be decorated with a tile or stone mosaic?  Are there mortar and grout mixes that can take that kind of heat?  Absolutely priceless video, thanks for all the diligence it took to put it out.  I'll use it for sure!

I see that dry fire wood is needed.  Should one avoid types of wood that have pitch?

strawboss wrote:
The artist in me just has to ask...Is there any reason why you could not or should not do something decorative to the outside of the barrel after completion? 

More than once I've heard Ernie or Erica say that you don't want to cob up the barrel because the heat loss is important to the burn properties. I think it has to do with keeping the temperature differential between the barrel and the insulated chimney as great as possible. I think the same would apply to decorative features that would restrict the heat transfer such as tile.

What a wonderful solution.  How does it work out with burning regulations?

Paul, what if you just sold your pattern? Print the core on card stock and sell that. It would ship efficiently and be a very valuable guide. The reciever just cuts, folds, and tapes. That would be an in between solution.

I could see templates for the burn tunnel, two heat riser templates and the barrel to pipe transition. Maybe for you it would be more valuable to give it away as a PDF and drive traffic.

strawboss wrote:
The artist in me just has to ask...Is there any reason why you could not or should not do something decorative to the outside of the barrel after completion? 

I think the important thing is that the barrel needs to be able to cool.  Another way of saying this is "give off lots of heat".  If you put stuff on it, that could be problematic.  If you weld or etch patterns on it, that could be fine. 

I suppose that if you welded on heat sinks and put on decorative stuff - the heat sinks should compensate for the decorative stuff.

vegan01 wrote:
I see that dry fire wood is needed.  Should one avoid types of wood that have pitch?

pitchy wood is fine!

vegan01 wrote:
What a wonderful solution.  How does it work out with burning regulations?

Regulations are going to change from point to point. 

Here in Missoula, these are legal for outdoor use in all of missoula county provided that they are used for non-sustained burns.  They are legal for indoor use on the north side of missoula county.

Jim Argeropoulos wrote:
Paul, what if you just sold your pattern? Print the core on card stock and sell that. It would ship efficiently and be a very valuable guide. The reciever just cuts, folds, and tapes. That would be an in between solution.

I could see templates for the burn tunnel, two heat riser templates and the barrel to pipe transition. Maybe for you it would be more valuable to give it away as a PDF and drive traffic.

Interesting idea.  That might take a bit more work. 

paul wheaton wrote:
A cast core could be made of .....  clay and perlite?  Plus something stringy to keep it from cracking .... 

A steel core is a possibility, although it would be a bit expensive.  And it could be heavy.

A cast core could be light and cheap to make - depending on the materials.

I wonder if somebody could get a cast set up and sell cores for $200 per core.  For a cast setup, the materials might cost about $20 per core.  For a steel setup, the materials might cost more than $200 per core.

www.backyardmetalcasting.com has a lot of good homemade refractory recipes in there forums - look under foundry engineering and construction.  Some great info when you consider that our burn tube and heat riser are very similar to a simple furnace like some of those guys are using. 

After reading around on their site I think I'm just going to try to get some 3000F castable refractory cement from a local boiler installer.  The last time I did a sustained burn (~4hrs) in my wood chip burning RS the inner pipe got hot enough to go soft and let some of the rocks that were used as insulation deform the pipe.

Wow... I must say that I am impressed with what you guys are doing here.  I am the guy who fabricated the rocket mass heater from an old water heater over at The STReeTJeSUS Blog http://streetjesus.blogspot.com (mentioned earlier).  I've been pretty happy with the results of my stove and am actually thinking about fabricating something a bit more substancial that would serve as an outdoor furnace and would burn just about anything... paper, cardboard, etc.  I'm happy to say that I've been cutting my electric bill in half for a good while now.

A few pointers from my experience... Go with duct larger than 4 inches as it will draft better.  6" or 8" is much better.  Solid steel pipe through the wall is nice, and if you can go through masonry for the outside duct it is even better.  You can put a booster fan on the exhaust to make sure you have a good draft, but it should have a speed control so that you can tweak it so that is doesn't suck all of the air out of your house.

Check out Ianto's ebook about rocket stoves... He really can light the way to a successful project.

Cheers,
The Brentster

A rocket mass heater combustion chamber is mounted on top of a conventional wood stove. 

Ernie Wisner has built over 700 rocket mass heaters and this is his third hybrid.  In three minutes he covers a lot of detail about the efficiencies of conventional wood stoves, rocket mass heaters and hybrids.

paul wheaton wrote:
We had a point and shoot thermometer and were testing the temps of a lot of stuff. 

The duct was not getting very hot.  I think the highest we measured was around 140.

on that last video  what was the time lapse?

samiam wrote:
on that last video  what was the time lapse?

I don't understand the question.

I am strongly considering building one of these. I am a renter of an old brick building with wooden floors. there is a chimney stack running through my bedroom (whose only source of heat currently set up is space heaters) with a 6 inch hole all ready.

I have some questions. In Ianto's book, he says when building above a wooden floor to leave a three-inch air gap under the combustion unit, glue aluminum foil down on the floor, and to use a minimum of four inches of insulation  under the stove and the whole of the heat storage. so my question is, paul, are your specs intended to be used on a wooden floor? I've heard you say that was an intention of the project overall. I'm thinking I will put a wooden bottom on your frames and have the whole box held up off the floor by three or four 4 by 4s.

also, this bedroom is small, about 20 feet by 7.5 feet. with how I'm imagining positioning the stove in the room, my bed would be snug up along side the portion of the box containing the heat storage. is that dangerous and stupid or potentially really cozy and nice?

any thoughts are welcome.

tomcampbell wrote:
also, this bedroom is small, about 20 feet by 7.5 feet. with how I'm imagining positioning the stove in the room, my bed would be snug up along side the portion of the box containing the heat storage. is that dangerous and stupid or potentially really cozy and nice?

The Russian peasants have built their heaters big enough to put the bed on top for hundreds of years...  There are some pictures here:

http://www.pyromasse.ca/articles/75kmwest_e.html

And in the video at the bottom of this one there is a child peeking out from the bed on top.

http://kirpichiki.pro/engl/pancakes-in-russian-oven.html

Very massive! The secret is that a RMH is not a continuous burn machine. The burn is done before you go to bed... and the fire is out by then. The mass stores the heat all night long and into the next day when it is fired before using the bed for a few hours. So it is important to start the fire long enough before bed to get up to the right heat before bed.

I have a special request.

Right now I am scrambling to get the forums moved to the new forum software.  This will take more than a week. 

In the meantime, I have received about a dozen requests for detailed plans on how to build what is in the video.  Version 1.2 and version 1.3 are the same - so that is what I am thinking would be good to have plans of. 

If there are a dozen people asking for plans, I suspect that there are a couple hundred more that want plans but haven't asked.  And then maybe a few thousand more as the years pass.

Is there anybody out there with the ability and inclination to make such plans? 

I have an odd use for this idea.

I have been lolligagging around making a heating source that is green for my home (hope to be changing that in the coming weeks.

A buddy showed me the RMH and I found my way to this site (I am also wanting to shift to homesteading too - maybe not as completely as some here) and I thought it would be a potential way to save heating the back of the truck vs plugging a space heater in (I do carpet cleaning) to prevent water hoses from freezing and breaking.

To make something like this "portable" would it be possible to mount the bench pipes and leave them in place and the burn unit/ core can be assembled/ disassembled into 3 parts or so or  be a slide in/out?

or if I just went with the furnace part but not the mass part and insulated the inside of the cub/ back would that give me the heat and preservation of that heat to last over night or so?

I live in Northern Indiana

Also by making this a slide out it could be used to augment the heating of the house when not in the truck (or I could make two and one is permanently in the house.

so I'm gathering materials now, and I just happened to see a comment ernie made after one of the videos responding to someone's concern over using galvanized pipe saying that the inner tube of the heat riser is stove pipe instead. that's an important piece of information that I almost missed! does the outer tube of the heat riser not also need to be stove pipe? seems like the temperatures there would also be pretty hot still, what with that torus thing happening and all.

also, I'm curious about what the updated heat riser is sitting on- the perlite? is there any reason to not have the cut out for the connection to the burn tunnel be at the very bottom and have it sitting on brick?

Tom, in mine, the inside of the heat riser is stove pipe, and the outside is galvanised tube. The top 1/4 of the lengh is black, the following part is yellowing because of the creosote or else, i've seen galvanised offgasing before, and this is not looking like it. And the half left is slightly offgasing may be, but is still looks like galvanised, it's not yellowing from offgasing yet.

Anyway, if you find galvanised tube from hvac for example, you give it a good burn in a bonfire and it will ofgas there.

Hello Paul,

Thank you for this detailed journey.

I am planning to build a similar but also  different version which includes a standard rocket burner connected to a bench that is similar to what you created - wood-framed bench with pipes and pea gravel.

Because the actual rocket is not inside the bench, many of the space challenges you had are not a problem for us. However there is one detail that comes up that I haven't yet figured out - and that is how to get the pipes safely into (as they come out of the rocket) and out (as they continue to the exit flue) of the wooden box = wood doesn't heat up or burn.

Do you have any idea how to achieve this?

Thank you in advance for any ideas

Ronen

iamronen wrote:

Because the actual rocket is not inside the bench, many of the space challenges you had are not a problem for us. However there is one detail that comes up that I haven't yet figured out - and that is how to get the pipes safely into (as they come out of the rocket) and out (as they continue to the exit flue) of the wooden box = wood doesn't heat up or burn.

Use double/triple wall stove pipe. It is made for the job... or make your own... 6 inch single wall stove pipe wrapped with roxul (or equiv.) with bigger pipe (8 or 10 inch) outside of that.

Hi everybody!

Len, i dreamt of a rocket last night! That's it i'm a weirdo

I had this vision in my dream of a metalic closet, like old electric switchboards

http://upload.wikimedia.org/wikipedia/commons/thumb/7/71/Electrical_switchgear.JPG/800px-Electrical_switchgear.JPG

With a rocket in the midle, with the walls lined with bricks, the back having few layers of theses to accomodate the flue. Just something wich just crossed my mind, i could build a flatish metal flue to keep the space tight.

There's definately room for evolution and design with thoses rockets.

Another thing, if it's big enough to close the doors, i could build it so it can be open to radiate heat, or closed to accumulate heat.

I've gathered some thick walled six inch pipe today, but just barely enough to make a new feed tube and burn tube, but not cyclonic. At my local supermarket there's two lenghs of 7"ish 17cm, thick walled steel pipe, some 4 meters long, lying on the ground. I wish they would look somewhere else while i pick them up.

I need to find a 3'x3'x6' metalic closet!

Satamax wrote:
Len, i dreamt of a rocket last night! That's it i'm a weirdo

I had this vision in my dream of a metalic closet, like old electric switchboards

http://upload.wikimedia.org/wikipedia/commons/thumb/7/71/Electrical_switchgear.JPG/800px-Electrical_switchgear.JPG

Reminds me of some of the radio and TV transmitters I once worked on.

With a rocket in the midle, with the walls lined with bricks, the back having few layers of theses to accomodate the flue. Just something wich just crossed my mind, i could build a flatish metal flue to keep the space tight.

There's definately room for evolution and design with thoses rockets.

Another thing, if it's big enough to close the doors, i could build it so it can be open to radiate heat, or closed to accumulate heat.

I've gathered some thick walled six inch pipe today, but just barely enough to make a new feed tube and burn tube, but not cyclonic. At my local supermarket there's two lenghs of 7"ish 17cm, thick walled steel pipe, some 4 meters long, lying on the ground. I wish they would look somewhere else while i pick them up.

I need to find a 3'x3'x6' metalic closet!

They are called 19inch racks... though the picture you gave doesn't look to have any standard ones in it.... actually that is what made me think transmitter. I saw more 19 inch racks in the studio.

Anyway, what you have suggested has been done... well sort of. There have been Russian masonry heaters made with brick inside a steel shell. 24inches square or so and 6 or 7 feet high. Not rocket tech, but similar. Funny, my RMH stage one will be 25inches in diameter. However, the steel is inside and the bricks outside. I should go do some work on that now...

I added the mass to my portable. (portable means same as Paul's... takes an hour or so to assemble/diss)


I found adding secondary air got rid of all my smoke... that I could see. This one does have a smaller foot print being 25 inches in diameter.

Thread here:
https://permies.com/permaculture-forums/10653_0/alternative-energy/yet-another-portable-rmh

Len, in the winter i work for a chairlift compagny, and we have all sorts of electrical closets which are not 19", well the old lifts are disapearing, and we get more and more into that depth range  of 50cm, may be we still have some 60 on the new ones. I'll have to measure when i get back up there.

Satamax wrote:
Len, in the winter i work for a chairlift compagny, and we have all sorts of electrical closets which are not 19", well the old lifts are disapearing, and we get more and more into that depth range  of 50cm, may be we still have some 60 on the new ones. I'll have to measure when i get back up there.

Sounds good. The 19" BTW is not the outside dimension,  but the width between the mount rails inside. Many are quite deep and have rails front and back. I think the one beside me (holds my computer. printer, paper, scanner and switch) is 24x24 outside, but it is smaller than most depth wise. However custom made ones like you have can be much bigger. I'm not sure though what the advantage is to using a metal casing over the brick unless it is that it allows dry stacking the brick.

Well, you know what can pop in one's mind during sleep. Yep dry stacking the bricks, and also the possibility of closing it to hold the heat when the room is warm enough.

Satamax wrote:
Well, you know what can pop in one's mind during sleep. Yep dry stacking the bricks, and also the possibility of closing it to hold the heat when the room is warm enough.

Insulation too then.... sounds like one of my solar ideas.... using yet another water tank core.

okay, since paul is busy switching the forums and no one who is able to has taken up his special request to lay out the specs for his versions 1.2 and 1.3, I'm figuring it out the best I can as I try to build it.

It's tricky, though, to have read the post at the beginning of this thread and to have watched the video because one is tempted to think that they are consistent with each other, but I just noticed that the barrel in the video is probably a 16 gallon drum and not a 30 gallon (I've been wondering about what would be a 4 inch gap between the heat riser and the heat exchange barrel, given the combination of a 30 gallon barrel and a 10 inch outer duct for the heat riser!). woops.

Tomcampbell, i'm under the impression that it would exctract more direct heat, since the volume to be filled would be bigger. It would take more time for the hot gases to travel from the top of the heat riser to the bottom of the barrell where the flue is, suposedely cooling the gases more. But i wonder if this wouldn't slow the flow too much and impair the exhaust of the gases. Plus, air or gases with mixed air being an insulator, who knows what can happen. I know there should be convection movements in that space if the flow is slow enough. But who knows!

Best way to know is to try it.

Hth.

Max.

tomcampbell wrote:
It's tricky, though, to have read the post at the beginning of this thread and to have watched the video because one is tempted to think that they are consistent with each other, but I just noticed that the barrel in the video is probably a 16 gallon drum and not a 30 gallon (I've been wondering about what would be a 4 inch gap between the heat riser and the heat exchange barrel, given the combination of a 30 gallon barrel and a 10 inch outer duct for the heat riser!). woops.

It depends on which gap is meant. the gap at the top is determined by the inner diam of 6inches. with a CSA of 28 sqin. That would seem to make the clearance or head gap about 1.5 inches, but he (and others) have found 1.75 works a bit better. By the time the flue gas gets to the outer riser shell of 10 inches, even a one inch gap is over 30 sqin. This should be plenty so far as CSA goes. However, I have heard more than once that a 6inch system is the smallest that works well because of surface friction. So I am suspecting there is also a minimum gap for long runs even with a constant CSA. It seems to be less than 6inchs though

The other consideration is the barrel exit which is also 6inch and therefore would require at least a 1.5inch (or 1.75inch to be safe) gap all the way around assuming the flue gas has equal opportunity (this is sounding like a contract where I work ) to get to the exit from all directions. This is probably not the case because the exit is quite near the bottom of the space and so the bottom 1/3 is some what blocked. So to be safe I would add at least a third more and try to get at least 2.25inches gap or use an 8inch duct out and then reduce to 6inch.

Just something i have noticed on the forums as people have built a RMH, this barrel exit area has caused problems for a number of people. They have had to rework it to get it big enough. So this is one of those "pay attention" areas.

I don't know the barrel sizes off hand.... for two reasons... one they are not the same here. I am from Canada and our old 45gal drum is 55gal in the USA... not sure where that came from as the gallon was originally 10 pounds of water. So any size drum you are talking about may not make sense here. Second, I have not seen any floating around and so don't have access to any to measure. I have ended up using a water heater core with an 18inch diam. and 4feet high. This has allowed me to have the exit within the barrel. It has also meant the top is rounded and not flat. Harder to set a pot on, but doesn't seem to have effected operation.

I hope I have given enough to play with... all of these are prototypes and as always should be built and tested outside first.

Well folks I've been away for awhile and very busy, I'm setting up a production facility (my barn) to build RMH stoves, including cast refractory "cores" Fire boxes and catalytic chimneys.
After playing with my "portable" RMH and making various modifications I believe I have a very good working prototype. The basis is a rocket stove separated from the mass, this allows for the mass to be incorporated into a piece of furniture or in a crawlspace (under the floor). I've found the efficiency of the stove is greatly dependent on the chimneys heat conductivity or lack there of, the firebox is less critical but does help if its conductivity is low. Due to my normal business nose diving in this economy I'm hopeful this will fill a need, help people and maybe provide a bit of cash flow.
I live completely off grid and some what in the stone age, hence I only get to a computer once in a while, my next visit/post will include pictures if not a video of the first production unit.
Be back soon
David

I did it! I made a "portable" rocket mass heater. It is installed in my bedroom. And it works... for the most part. Sometimes it stops drawing and smokes into the room, but it starts up again if I give it a good blow.

Here are some specs: It is in a 10 foot long by 22 inches wide wooden box that is lined with aluminum foil and held three or four inches off the floor by 4 by 4s, and all of that is sitting on cement board (all of which may be unnecessary). The wooden box has a hardware cloth window along the length of the side of the mass portion of the stove that faces the room/my bed to let the stored heat radiate out more easily. It is a 6 inch system. The feed tube is 5" x 6" and the burn tunnel is only one flat brick wide. I have a thick steel pipe for a heat riser, three feet tall (which makes the whole of the heat riser 3 feet and 7 inches tall). My heat exchange barrel is an 18ish gallon barrel. I have 25 feet of exhaust pipe (not including the length of the turns) running back and forth just like paul's prototype. That piping is plain ol' HVAC galvanized pipe. And there's a monstrosity of bricks cobbled together to connect the barrel with that pipe. I'm still gathering bricks and pea gravel to fill in around the exhaust pipes. I have two t joints with caps in the exhaust pipes- one right at the beginning for cleaning out ash, and one right before the vertical turn to the outside chimney in case I need to warm up the pipes to get the draft going. The HVAC t joints and caps didn't come crimped or whatever its called so one can slide into the other, and I think my DIY job of it left too much gap because smoke was escaping out from around the cap, so I taped it up with aluminum tape for now.

YAY! Thank you, Paul, for your inspiration.

tom campbell wrote:I did it! I made a "portable" rocket mass heater. It is installed in my bedroom. And it works... for the most part. Sometimes it stops drawing and smokes into the room, but it starts up again if I give it a good blow.

Looks great.

So I've fired the stove three times now. The second time I did not have any smoke back. It appears that it only is happening when the fire creeps up the fuel out of the feed tube into the open air, which happens when the wood doesn't crumble and fall down with gravity as it burns. the first burn had wood in it that I put in small end down, big end up, and I think that was the trouble there. the second fire I used very uniformly sized wood.
so it is appearing that this stove works but requires a lot of attention to push wood down as necessary (at least every 10 minutes). does anyone have suggestions for how I can change something so that the wood doesn't hang up on itself or each other and falls into the burn tunnel on its own? is it reasonable to want to get to a point where I feel confident in walking away for a time from the fire while it's going on?

the feed tube is 5" by 6", and 10 inches tall, but the top layer of bricks are not mortared in, so it is adjustable in being able to slide those bricks away to make it shorter. but could it benefit from being taller? or should I have a cylinder of hardware cloth above the feet tube to funnel the fuel in? I don't have a small barrel around the feed tube as they describe in the book. is this the problem that that addresses?

p.s. is there a less clunky way to post photos? how do people do it without all the attachment info junk after?

tom campbell wrote: does anyone have suggestions for how I can change something so that the wood doesn't hang up on itself or each other and falls into the burn tunnel on its own? is it reasonable to want to get to a point where I feel confident in walking away for a time from the fire while it's going on?

In haven't built mine even nearly the same but I had the same concerns. Mine has a metal feed and I use a cartridge that is three feet tall and sealed. I have an air intake instead of using the feed hole for that. See:

https://permies.com/t/10653/alternative-energy/Yet-another-portable-RMH

For pictures of what I have done.

p.s. is there a less clunky way to post photos? how do people do it without all the attachment info junk after?

Yes, if your pictures are on another web site you can use the "Img" button above the edit box to surround the url of the picture. This also lets more pictures be included in one message as well as letting the text be included under pictures. The only thing to watch for is that the picture will be the original size and if it is too big, as most images direct from the camera are, the reader will have to scroll around to see the whole thing. The attachment "junk" is to allow the inclusion of copyright info if it is not a picture that was taken by the poster of the message.

found this on youtube (a year old). emailed the poster but haven't gotten a reply concerning the insulated gas pipe riser. Not sure about the flat top; maybe the part came that way? Was it welded on? He doesn't give any information on construction. earlier posts show the prototype using all tin cans. Pretty small and portable; would seem to work well for a small room or for supplemental heat.

http://www.youtube.com/watch?v=B4mr7Z6I5Bs&feature=related