Rocket mass heater.

A rocket mass heater by an amateur. I researched this topic for weeks and the more research I did, the more my head was spinning. So I decided to start building something and see what happened. Keep in mind my limitations; no experience, no masonry skills, no money, zero on the money, know nothing about cob. That list of things I don't have or know could go on forever. What I do have is some salvaged bricks, mostly not good firebrick at all, a pile of scrap wood, some barrels, and a greenhouse to heat. I did some digging and started stacking loose brick.

Where I am at now is a fire breathing beast. I can't believe the heat. Now I need to get a barrel in it an exhaust. It is March 8th now and I only need this thing to last about 2 months. Then I can make something better.

Any quick suggestions now? I am so excited about this heat so far that I had to post something. Hopefully I can figure out how to post a video of it going. My 48 second video is too large so I am posting a link to it.

https://photos.app.goo.gl/SBd0iiQSTqh7II653

Well, this was a learning experience. Not performing so well, as you could imagine. But now I do understand more of what I was reading. And in searching for answers to specific problems I have found much of the info I had been unable to locate before. Tearing it down and beginning anew tomorrow.

So, the best advice I have ever seen for building a RMH is to start stacking loose bricks and see what happens. I stacked and learned how to build garbage, a actual RMH that was a fire extinguisher, and finally the real deal.

LESSONS LEARNED:
1: The proportions matter on lengths, area, sizing, cross section, etc. Don't try to reinvent the wheel. I tried. I failed.
2: If the ratios are off it can be the burn tunnel being shorter, there riser being larger and/or taller,  or the riser being farther from the barrel.
3:  Riser height! Riser height! Riser height!
4: Learn how to make cob. It is easy and a forgiving material if your location doesn't require good looks. For good looks, I need more practice lol.
5: There is a reason I could not find a perfect cob recipe. It is an on the job thing that goes by feel and the nature of your material. My clay, from posthole I had to dig, came with plenty of sand. Adding much more sand ruined it.
6: Start with a small project and don't expect it to go fast and easy.
7: Cob is heavy, messy, and sticky. Be prepared. Having a bucket of clean water around is handy.

Welcome Randy and good for you being willing to challenge yourself with such an ambitious project with so few resources.

Most of the people here are friendly and willing to share their knowledge. Most of that knowledge is from trial and error experiences, with an accent on the error part. The reason those dimensions and ratios are out there is because of the high failure rate of those of us with little to no experiences to draw from.

I look forward to seeing how you and your project progress.

It works, not perfectly, but it works well enough to keep my 19 x 12 kit greenhouse heated through the the rest of March and April. More importantly I learned enough to think that I can heat my 20 x 40 next winter with a better build. I will be scouting and scavenging materials all summer. Going batch box, 8 inch for the next one, horizontal barrels of water over the exhaust, plant tables over all that. Between some passive solar,a RMH, and insulation I think it can be done. I have researched the life out of it and I am not done reading yet. None of it would be possible without this forum and the people on it. Rare to find a forum where members pass up the easy opportunities to troll newbies. Very nice and patient people here.