Rocket Stove Dimensions

I'm reading "the" Rocket Stove Book.   If I were to use  1/4" thick 8" steel pipe for my heat riser, and insulate an old water heater (20.5") around that, I'd have 6" of insulation?  20-8=12/2=6..... Is that OK??

I am thinking about building a nice rocket mass heater for my new greenhouse and want to do it right.  I would like to talk with someone who know what the best materials to use are and the correct, most efficient dimensions and measurements would be?

Would a 24 inch, 1/4 inch steel pipe with a 3/8 inch flat piece of of steel welded on top of it work just as well or better than a barrel?

I just have a lot of questions and really would like to be in contact with someone who had been through this before.

Thank you very much.

I am having similar questions. With an 8" sysem, the recommendation is a 55 gallon drum with a 1.5" space on either side for the exhaust gases to flow down the sides. This gives us 8" (exhaust pipe in heat riser) + 1.5" (x2 - on either side of the heat riser) = 11". If a 55 gallon drum is 22.5" in diameter - that gives us: 22.5 - 11 = 11.5" / 2 (for the insulation of the heat riser) = 5.75" insulation around the 8" heat pipe. I think it's right - but none of the videos I've watched looked like they had nearly that much insulation. Please help.

Tom K.: Have you been to rocket stoves.com and downloaded your pdf copy of Ianto Evans' great book 'Rocket Mass Heaters' ($15.oo U.S.) ?

In my next Rocket Stove build I will use a piece of lightweight 8" stovepipe, for my Heat Riser, and use the shell/metal skin off of a hot water
heater cut down to make a form into which i will pour my perlite/clay slip insulation, This is doing it on the cheap, I expect the inner 8" stove pipe
[actually a cold air return - lighter weight ] to fail within 2 heating seasons, at which time I expect there to be replacement super insulative/efficient
Heat Risers for sale, If these replacement parts are not then available, I expect the remaining hollow column of perlite/clay slip will serve as my
Heat Riser for a few more heating seasons, failing in that I will just rebuild the whole internal plumbing part again.

This is a long winded way to say that the most efficient way the Heat Riser can work is to come up to high temperatures quickly,Which is the 1st
job the insulation has to perform, as the heat radiates off of the barrel the cooler gases fall creating the heat pump that allows the exhaust gas to
flow horizontally through the thermal mass. So keeping the high temperatures within the Heat Riser unaffected by the reduced temperatures found
at the barrel is its second job.

For a 8" system, generally the gap to the underside of the top of the barrel, should be 2" - 3" and the gap at the sides of the barrel 1 1/2"-2''

Relax, enjoy, try all your builds outside before you do a complete Rocket Mass Heater installation. You will notice that I have posted my
approximate location as part of my profile information, I can't speak for you but If you list an area within our home state you will probably hear
from out like-minded individuals who are close to you !

Be Safe, Keep warm, Pyro magically Big Al

Big Al.

Thanks for the post. I appreciate it. I am excited to begin my journal with the rocket mass heater - I just want to do the best possible. I am going to look into getting Ianto Evans' great book 'Rocket Mass Heaters' ($15.oo U.S.) - thanks for the advice. I am also thinking about using insulated triple wall pipe for the heat riser, and maybe adding extra insulation around that to get the necessary diameter I'm looking for. Whatever I do, I will make sure to post it - along with the results, so others may benefit from my experiments!!

Thanks again Big Al - I truly appreciate it!!!
Tom K.

Tom K. : How are you coming along on your project !

For the good of the Craft, PYRO Logical Big Al