• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education skip experiences global resources cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • r ranson
  • Anne Miller
  • Pearl Sutton
  • Mike Haasl
  • paul wheaton
  • Joylynn Hardesty
  • Dave Burton
master gardeners:
  • jordan barton
  • Greg Martin
  • Steve Thorn
  • Carla Burke
  • Jay Angler
  • Kate Downham

Building a tiny RMH for my tent in the woods

Posts: 2
Location: Santa Rosa, CA
forest garden fish writing
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am living in a 20' bell tent in the woods above Santa Rosa CA. The Tubbs fire burned all structures on the property, and we're rebuilding (using nonflammable materials!). It doesn't freeze often, but it rains a great deal (35"-40" yearly precip, the vast majority of it in winter), which makes for chilly and moldy conditions. I don't know how long I'll be in this tent-- at least a year, probably several-- but it's likely that some other structure will ultimately be built in this spot, so I want a stove that can be moved! A typical 6" RMH would probably be overkill for my temperatures, not to mention very massive, but I've read that anything smaller than 6" won't draft well enough to work.

Then I found this thread, with a very exciting new design style!! https://permies.com/t/71576/tiny-house-rocket-mass-heater

If I understand it correctly, this is basically a mini masonry heater; it's a 4" cross-section batch box type, with a bell stratification chamber made of bricks instead of a barrel or bench. It's about 5' tall, 32" deep and 24" wide, and weighs approximately 1 ton. That's small enough to pick up with a forklift or the like! Heat takes about 7 hours to soak through a layer of bricks, but cob/stucco can be added to the outside/top to increase the mass-- maybe it could hold enough heat to keep me warm through the night?

The only problem I have with this design is the height-- my tent has very limited headroom, being conical in shape, and a bench would've fit nicely closer to the wall. I doubt I can make it any shorter; the riser needs enough clearance, and the taller the bell the more effective the stratification, so I'm going to try to stick closely to the original design and not mess with it. 5' tall will work, but I'll have to place it closer to the middle of the room than I would like.

I wonder if I can get it built fast enough to use yet this winter?? I do NOT want to shell out hundreds of dollars for a conventional wood stove that'll be all smokey and not hold heat just for a few weeks of use, but while I'm building a stove I'll be real cold till it's done... and do I build it IN the tent, or outside the tent and test it and THEN bring it in? I think I'll try building the base, the firebox, and the lifter outside (I want to see if I can tweak the port shape to get the double rams horns, which will be interesting since the design is asymmetrical!) then bring it into the tent and finish building the bell over top where I can stay dry. I'll need to decide where to put the stove jack in my tent roof for the chimney.

Oh my! So much to figure out!!

Um and meanwhile I've never built anything like this before and have no masonry experience, so.... :D
Posts: 207
Location: Western central Illinois, Zone 6a
hunting trees solar wood heat rocket stoves ungarbage
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Sorry to hear of the losses from the fire. Can you post pictures of the site/tent where you plan to build this? I have not built anything like the RMH you linked to, but from the thread photos I believe it could be built on a skid or steel plate that would allow it to be moved. The thing with the RMH though is they tend to be unique to a location. My recommendation if you want to relocate it later would be to look into a pebble style or use non or less permanent construction methods that would allow disassembly and reuse later. I think once you build a RMH you will want to build more, and in different sizes and configurations.

My own unit, under construction, is a 5" system and we have been very happy with it. If I could change anything about it, I would do with a larger diameter bell, but where I built it would not allow for a larger bell.

Keep us posted on the progress!
Posts: 3664
Location: latitude 47 N.W. montana zone 6A
cat pig rocket stoves
  • Likes 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi L;  Welcome to Permies!

Yes the "casserole door " build is very nice.  It could be built with a flat top and possibly wider  to fit in your location. The internal surface area is the important number, not the shape.
As far as being movable with a fork lift... Yes ... built on a forkable pallet... very smoothly and not very far it could be done.  Thing is, it is mortared with clay , any bouncing, swaying or banging and it will break. The good news is ... that its mortared with clay...  pick up the pieces, rehydrate the mud and build it back up again.
Have you seen this build    https://permies.com/t/43809/Masonry-stove-diy-build-feasible  
Working with clay as a mortar allows a novice to try his hand at masonry, its very easy to start over .  Yes, you to can successfully build with brick.  
Posts: 3113
Location: Upstate NY, zone 5
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I would suggest that if you can use clay mortar, just build it exactly as shown in the thread, not worrying about making it portable. Then when your circumstances change, disassemble it, wash the bricks off, and you can build another that is exactly suited to the new location.

From Erica's comments, it seems that this particular build hits exactly the right balance between heat extraction and good draft, so I would be hesitant to alter it without testing - which you don't have time for. The one thing I would consider changing is to go to a flat metal top, for a cooking surface, while keeping the internal surface area the same.
Rocket Mass Heater podcast gob
will be released to subscribers in: soon!
    Bookmark Topic Watch Topic
  • New Topic