RMH Multifiuctionality (heating and cooking)? Rocket mass heater on a Tiny house

Hi all fire geeks

read THE book a while ago, and been interested in RMH for a while.

Also done a couple of portable Rocket Stove while on a nomad bicycle community (www.ecotopiabiketour.net) and loved to cook on them, fast to lit and cook and less wood burnt (less to pick )

me and my partner are now building a tiny house, around 4mx4m space and always fancied the idea of a Rocket mass heater bench ... starting now to plan mentaly where it would fit and start looking for materials.

i never saw one live, and realized all the videos and pics i saw the barrel stays very high, and never anyone praises it for the cooking hability on top of the barrel...

is it possible to design a RMH that also is used for cooking regularly (so the top of the barrel shouldn't be too high)? could i follow the 15cm (6'') design of the book and shorten the barrel? what would be that limit? and what's the consequence of a shorter barrel? i remember reading about making the barrel longer would make it burn more efficient, does a shorter one not be able to draft?

or should i start thinking on a duo rocket stove like the one of donkey (http://donkey32.proboards.com/thread/11?page=4), and how to connect both?

J.Tabordiy : Am sending you a Purple Message ! Big AL

thanks for all the tips al

our plan is to build the RMH on a second floor wooden, part of the weight will be over the stone wall of the first floor, it's all still hypothetical, as the house is not that big (check https://permies.com/t/43534/timber/Ruin-structure-sketch-Roundwood-tiny) for holding a full sized RMH 6'' (15 cm, non european standards are still hard for me to follow)

i wonder if a 5'' (12cm) RMH would be an option, it would require a lot of attention to start, and keep firing, and down-scaling to 5'' could leed to which other problems?...

and if one would downscale (in weight and size) the RMH 6'', what could be done?

6"/15cm is about the smallest size standard RMH that is said to be easy to build right - heat output scales down with at least the square of the diameter, and air friction effects don't scale down with diameter but become more significant. A 4" system is possible for experts or careful and lucky beginners, smaller than that does not seem to work.

However, a batch box combustion system has been tested to 4" diameter (possibly smaller), and as long as you follow the published specifications it should work well.
http://donkey32.proboards.com/thread/734/peterberg-batch-box-dimensions
You can add whatever thermal storage arrangement you desire after that, and in the Portuguese climate it will probably be sufficient to heat your small home. A 4" batch box would be much easier to tend than a 4" J-tube which would need sticks added every few minutes.

never read about those batch box rocket mass heater (is this the name?), is there any good posts/info on them i shouldn't miss?

looks like a possible solution, but but i would need to combine a cooking solution aside, is there info on using the same exaute tube for two diferent heaters?

J. Tabordiy : I have nothing against the batch box style Rocket Mass Heaters RMHs, except total lack of experience with them. Yes, I am being serious !

It actually seems that a 4'' batch box will 'Draw' slightly better than a j-tube style Rocket. The exact number of places (small places, small numbers ) where

this works in the batch Rockets favor is compromised by the need for an experienced Rocket D.I.Y. builder to assist your build.

Literally anyone who can follow simple instructions CAN build a RMH. My position here at Permies will be to suggest that it is our duty to assist future Rocketeers

tp build successful Rockets - I can think of few things sadder than a Fellow Member reporting that " Rocket Stoves don't Work " ''I tried it -they don't work,''

and " They're a scam !

For the good of the Crafts ! Big AL

Late note : Check back with donkey 32 pro boards ! A.L.