Rocket Mass Heater Practicality/Real World Use

Hello RMH Enthusiasts,

I recently purchased a bundle of plans from the Wisner's. I am reading through them and I have also been browsing the forum here to gather info.

I can't quite find an answer to my questions about day to day use. What does it look like? Will my dwelling experience wide temperature swings? Will I have to lite the heater often to maintain a reasonable range? What has your real world experience been with using the heater you have built?

My decision will not be solely based on efficiency in either direction. What I mean is that I could be persuaded because of the efficiency of the stove but I could also be persuaded by the efficiency of time savings in a traditional stove. Maybe they balance out in either scenario and it is a wash if you have access to plenty of firewood. Some real world operating info would be helpful, thank you.

We're at the early stages of testing ours, but this is how it seems so far...

1 - it uses a whole load less fuel than our previous stove, so there is less time spent collecting and preparing wood

2 - it takes longer to light than a normal wood stove, though it's getting faster each time and also our technique is improving

3 - we don't have to run it for anything like as long as a normal wood stove, so fewer re-loading sessions

4 - far less of a temperature swing than with a normal wood stove, which will improve even more when we finally get the heated bench built

Here's the thread about our build - matt walker tiny cookstove build in Portugal

Josh Hoffman wrote:I could also be persuaded by the efficiency of time savings in a traditional stove.

Josh,

If you put the batchbox, shoebox or shorty core firebox in a masonry bell it will be a traditional stove, but more efficient and cleaner. Also scalable and well documented (as opposed to esoteric designs without good scientific foundation).

Cristobal Cristo wrote:

Josh Hoffman wrote:I could also be persuaded by the efficiency of time savings in a traditional stove.

Josh,

If you put the batchbox, shoebox or shorty core firebox in a masonry bell it will be a traditional stove, but more efficient and cleaner. Also scalable and well documented (as opposed to esoteric designs without good scientific foundation).

Would a good resource for those configurations be to search through the forum here or is there another resource that would be a good read? Thank you.

I would start with;

https://batchrocket.eu/en/building
https://donkey32.proboards.com/

When you grasp the idea you can start designing and building and people on the donkey32 forum and on permies will help you with advice.
It's good to read a little and start building than read a lot and build nothing.

Cristobal Cristo wrote:I would start with;

https://batchrocket.eu/en/building
https://donkey32.proboards.com/

When you grasp the idea you can start designing and building and people on the donkey32 forum and on permies will help you with advice.
It's good to read a little and start building than read a lot and build nothing.

Thank you for taking the time to point me in the right direction!

Josh,

I was at the stage a year ago that you are at now and looking for the best possible heater solution for my needs. I settled on a batch rocket design that was highly engineered and developed by Peter van den Berg for more than a decade. His secret sauce is the combustion core which then provides you with a solid foundation from which you can decide how you want to implement the actual heater. Here is a link to Peter's website which is a must to read thoroughly if you want to go this direction: https://batchrocket.eu/en/. He provides all of the details required to achieve success.

In my case, I wanted something that can retain and radiate heat over a maximum period of time so my design is more of a traditional masonry heater. You have the option to have a higher degree of instant heat but not retain that heat over a long period by using a steel barrel design & bench. Your needs and desires will help to steer your design. Of course, you can decide to go with a simpler J tube design if that is more to your liking as opposed to Peter's combustion core. You will note that he now has multiple variants of his combustion core with the latest iteration being a Shorty core.

Thomas Rubino has just completed a Shorty build. You can see his build thread here: https://permies.com/t/267527/Shorty-Core-bell. Tom is a master rocket scientist and an invaluable resource for all things rocket mass heater. Note that Tom has at least 3 or 4 other heaters that he has built and rebuilt over the years with many different designs.

Here is a link that documents my build: https://permies.com/t/238503/Batch-Rocket-Build. Also, in my signature is a detailed list of materials that I used for my build. We absolutely love our heater... it works way beyond our expectations.

Wishing you a fun journey as you decide on design and build. The folks here will be happy to help you along the way.