beautiful rocket mass heaters

Built by a professional to code? Somewhere in the $10-30,000 range I would suspect.

Glenn Herbert wrote:Built by a professional to code? Somewhere in the $10-30,000 range I would suspect.

10k will get you in the door with a mass heater to code. This one would be closer to the high end.

A nice one from Germany i think.

http://donkey32.proboards.com/thread/1824/20cm-tube-half-barrel-indoor?page=1#scrollTo=18845

Sauna rocket (there is a mass heater under the wooden bench, and the feed access is from the changing-room adjacent)
from off-grid life, ben's natural building, or some such blog.

Here is the whole project: http://bensnaturalbuilding.blogspot.com/2013/02/rocket-mass-heater-designbuild-workshop.html

They had a 140 degree sauna, left the vents shut since it was 15 degree weather outside (or was it -15?). The room was still holding at 110 the next day.

-E

Discussion of these stoves at the rocket mass heater workshop jamboree

Len Ovens: “Some people however, would feel a line has been crossed and the heater is now a masonry heater even though it uses the same principles in it's operation.“
Are you meaning same principles as RMH, or same as masonry heater?
I’m barely at novice level for knowledge about either of these, but from the masonry heaters I’ve seen (Russian Fireplace, etc) the principles don’t seem to be the same, aside from heating a mass. The masonry heaters appear to be a firebox beneath a zigzag flue which eventually exits a vertical stack as cool gasses (co2, h2o). The mass has time to absorb the heat, but is there a high temp and/or secondary burn such as occurs in the RMH? The one I knew the most about was built by an ‘old country’ German couple, and they ran a hot fire for about 3 days, then the entire mass was warm and they built daily small fires to maintain that level. After the initial burn it didn’t use much wood to heat their large chalet style house, but the heater was probably 6’ square and occupied the center of both levels. I did various work for them in my late teens, and learned early the value of thermal mass.

Julie Reed wrote:Len Ovens: “Some people however, would feel a line has been crossed and the heater is now a masonry heater even though it uses the same principles in it's operation.“
Are you meaning same principles as RMH, or same as masonry heater?
I’m barely at novice level for knowledge about either of these, but from the masonry heaters I’ve seen (Russian Fireplace, etc) the principles don’t seem to be the same, aside from heating a mass. The masonry heaters appear to be a firebox beneath a zigzag flue which eventually exits a vertical stack as cool gasses (co2, h2o). The mass has time to absorb the heat, but is there a high temp and/or secondary burn such as occurs in the RMH? The one I knew the most about was built by an ‘old country’ German couple, and they ran a hot fire for about 3 days, then the entire mass was warm and they built daily small fires to maintain that level. After the initial burn it didn’t use much wood to heat their large chalet style house, but the heater was probably 6’ square and occupied the center of both levels. I did various work for them in my late teens, and learned early the value of thermal mass.

Yes I would say that any masonry heater builder today uses the same principles as the RMH. First set aside the the bench or other heat storage part of things as that is not what makes a "rocket" mass heater. What makes the rocket is the first stage to the bottom of the barrel. There are many batch box RMH designs these days and that seems to be the direction things are going. But both RMH and the masonry wood heater have the next portion, the riser where the flue gases are squeezed through a tube with a cross section similar to the exit flue to increase the velocity of the gases and finish burning the unburnt gases at a high temperature. In both cases this part of the rocket is fully enclosed and so not visible from the outside of the heater. Then the gas is redirected down around the rocket to almost the bottom of the heater in both cases and as the gases cool, they shrink and are pulled through partly by gravity (we think... at least that is the most common explanation in the RMH community that I have heard). After that comes heat removal by running the flue gases through mass. Both RMHs and masonry wood heaters do the same thing. Quite often these gases are run through a mass in the shape of a bench for heated seating. In the case of the RMH the bench is always used, probably because cob provides the best structural properties when used horizontally and because RMH are often built by amateurs who would like to avoid rebuilding the foundation to support the weight. Masonry wood heaters are most often installed by professionals who are going to add to the foundation anyway and their concern is how would the client like their stove to be. The clients on the other hand may want a more compact design with no bench or of lower price (10k CAD gets the cheapest build, but most even low end heaters are 20k and up) and so the mass is more vertical. But the thing that makes a rocket anything is the heat riser inside which acts as an internal chimney to both create draft and finish the burn. Both types add preheated air to the riser though not always intentionally. In my experience, intentionally works better. Most masons seem to agree from what I have seen.

Do note that not all  masonry wood heaters follow the exact same principals as the RMH, some are more like fireplaces in operation. However the particular model I showed in the message you quoted has pretty much the exact same flue gas flow as the RMH and even uses very similar kinds of dimensions all the way through. If you look through some of the rest of the threads here about RMHs, you will find some here that are even less like the original RMH than the one I showed. Look at the Walker style for example where the "riser" is horizontal   To some people The RMH has a barrel or it is not a RMH and you will not change their mind. I am ok with that too. In my case functionally the same is what is important.

I'm living in the first place that it doesn't sound ludicrous to buy clay!

http://naturalhomes.org/timeline/juured-rocket-stove.htm

https://greenlivinglab.org/2016/12/30/a-beautiful-rocket-mass-heater-for-the-green-living-lab/

So after several years of using my pebble style RMH in it's bare bones state I finally decided I wasn't going to do any major changes to it and should finish it off.  So I went hunting at the salvage stores and found some nice stone tiles and slate slabs.  I used some salvage wood trim from a friends home remodel.  I made up some more cob to fill in the weird little areas around the feed tube and barrel.  Then decided to make up a clay paint using the same fire clay I used on the cob to get a matching color on the wood trim.  Finally, since I'm a metalsmith working mainly in copper I had to splurge on some thin sheet copper to trim out the upper vent openings.  Seemed fitting since I used an extra large sheet of copper I had on hand for the back wall heat shield when I first constructed this.

David, definitely in the top 5 of all time rocket mass heaters.  Maybe even number 1.

I hope you have a thread all about the build with details about the core and the mass and stuff like that.

Do you have some metrics on how well it is performing?

Thanks so much Paul!  I'm quite happy with the look though I don't know that it really beats out all other RHMs out there in this regard.  I must admit I rather like the "rock and mud" look.  Alas my home wouldn't support that sort of extra heavy cob construction.  It was in fact your pebble style RMH in the Fisher Price house that made me say, "wow!  Really!  That works in a mobile home?  Awesome."  It gave me the confidence to try building this one in my old mobile home, and what do you know.  It worked for me too!

I had posted a few images in one or two threads that were active at the time, but never did a dedicated thread here on Permies covering my build.  I do have quite a bit about it on my blog site in this post

 .

I have yet to really see how performance will change with the addition of the added mass in the slate top and stone tile side panels.  I would think it will improve things some, though I don't expect anything too dramatic.  I do often describe my RMH as an example of an inefficient one.  I was unable to make it as large as would be ideal to transfer heat out of the exhaust due to the space restrictions in my tiny 1968 mobile home.  I didn't dare go with full cob due to the weight on the floor.  So it's a smaller pebble style.  That said, I found I used 50 to 60 percent less wood compared to my old soapstone wood burner.  With the old stove I would also often use the propane furnace a bit at night or when I was away for longer periods to keep the house from going much below 60 degrees.  I find it very rare I need to use the furnace for that now, basically only when I'm going to be away for days.  So I would say my propane use has also dropped by 80 to 90 percent.  (I still use it for cooking.)

MyLittleHomestead: https://www.youtube.com/user/mylittlehomestead/videos has built several RMHs and this one was rather fanciful:



They also show a quick shot of an underground RMH one of the boys made in his room. In addition to a traditional house, they have built several earthbag houses that became the bedrooms for each kid.

I would love to install on of these in my house but I would have to import all y'all to make it for me. Sigh.