I might be misunderstanding this but...the chamber part of a RMH doesn't need to be an actual barrel right? Could just as easily be made of masonry. Fire brick inner chamber and a normal brick for the 'barrel'? Maybe then covered in cob?
Also, is their some reason why the no build has ever had a 'u' shaped bench rather than the j or l shape they normally are?
Hi Robert; You are correct in that you do not have to use a barrel.
Using brick instead is called a brick bell. Quite a bit larger than a barrel but much more ascetically pleasing to look at.
And no pipes thru a solid heavy mass.
Yes, you could cover it in cob if you wanted.
Spend some time looking at posts here at Permies.
You will see examples of both, brick bells as well as a barrel and piped mass RMh's
There are traditional J tube rockets as well as the newer stronger batchbox designs.
Check it all out then come on back and ask questions.
We have a whole crew of happy rocket scientists eagerly awaiting your questions!
But don't wait to long or our group of rocket scientists could be "too happy"...
Robert Dickinson wrote:Also, is their some reason why the no build has ever had a 'u' shaped bench rather than the j or l shape they normally are?
I have seen quite a few over the years that have been U shaped but generally they are not with a piped bench system as it creates a lot of turns that put a lot of drag on the gas flow which equates to a sluggish and therefore potentially dirty burn. Matt Walker has built one from half barrels at an Innovators Gathering one year at Wheaton Labs dubbed "the ring of fire" which has no pipe but acts as a large stratification chamber instead. The end of the bench in either case would take a long time to warm up and therefore not really be adding much benefit for heating purposes other than a bench to either sit or put stuff on.
If you are thinking of doing a bell style half barrel bench and run the exit flue out from near the core I would recommend running a length of pipe, inside the bell, to just before the deadend of the bench. It really helps to promote the hot gases to circulate throughout the entire chamber. I tried it first without, and then got the tip from Matt Walker. It’s like night and day as far as getting even heat.
Hope that helps.
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