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Sauna & rocket stove - j6 or j8 ?

Posts: 6
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I’ve been lurking for over 5(?) years on this forum ...and the time is finally come to post. I’m building an 8sided sauna in my backyard. I was planning originally on having a rocket mass heater inside (with the feeder box outside  , to keep smoke out), running pipes under the benches on the inside. But... I don’t know what size would be optimal. I want a stove that heats quickly and  absorbs  heat well So the heat from the exhaust pipe is cool...but the actual area of my sauna is so small… Could I get away with a j6 inch system?  I don’t want to build a system that burns too hot if I don’t need to.What are your thoughts ?👍🏼🙏🏼😀
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Pipe layout
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20”x20” butt placeholders , pipe, door
Posts: 3653
Location: latitude 47 N.W. montana zone 6A
cat pig rocket stoves
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Hi Vince; Welcome to the wonderful world of rocket science!
A 6" J tube will be plenty for your sauna. You may want to cob 50% of your barrel to slow down radiant heat.
If I read your design correctly it appears you are right around the 30' of pipe recommended for a 6" system.
Have you considered "bell" benches in place of piping ?
Take lots of photo's as you build, our happy crew of rocket scientists is eagerly awaiting guiding you on your first build.
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Happy Rocket Scientists
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Early prototype
Vince Panero
Posts: 6
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Thank you Thomas! Actually I was wondering about purchasing (or finding) plans to do a small bell style rocket stove or a 6 inch J tube style rocket stove… I’ve heard of Ernie and Erica’s j-6 plans somewhere on these forums, But I have not heard of another stove plan that is thrifty on wood but also warms up fast. Maybe the cyclone bell rocket is in the running— a stove that was covered in a permies video that I saw a recently.  Is that what you were referring to?  Is there a tried and true trusted plan for a stove like that by chance ?
Lastly, is there a rocket stove version that heats up very quickly?  My sauna is small, will be thoroughly insulated via clay slip or lite straw clay , With 4 to 6 inch wide insulated  roof/walls... should be able to  hold the heat for a couple hours of a sauna session. 150-180° tops target temp in room.

Given the fact the size of the sauna is so small, would a 4inch tunnel design cyclone bell style work? How small could I go ? I feel a 25 gallon barrel would be over kill. Thoughts and opinions welcome 🙏🏼 Thank you all !
Posts: 611
Location: Wellington, New Zealand
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You could ask Matt Walker/Remine how his rocket sauna worked out?
Posts: 129
Location: South Australia
duck chicken solar
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I have been a part of two wood heater saunas. The second was a small sauna with a 4.5" batch rocket. The thing cranks to 130c with that heater. We find that between 65c and 80c to be a good balance so it is more than enough power.
Yours is a lot larger but I would think even a 5" would do the job.
Adding mass will cause it to take a very long time to heat so I would advise just using a barrel with some rocks on top. That way you can still use water on the heater but get instant heat when you light the fire.
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Any progress or updates on this? I am new to the forums and have already built my 8 person barrel sauna. The stove that came with it took up too much room so I am looking to alternate ideas right now. I started building a 4" square tubing based rocket stove and was just thinking about surrounding the heat riser with sauna stones for thermal mass, but also considered an idea much like yours for a RMH. My sauna is a barrel sauna so it is not insulated, but built from 1.5" thick cedar staves.

I would love to see photos and hear about the progress. Happy to share progress I am making as well. Currently I have part of it welded up and have a pellet feeder working pretty well so far. Here are some photos. I could easily convert this to RMH if you are having any luck.

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Posts: 1213
Location: Westbridge, BC, Canada
building solar woodworking rocket stoves wood heat greening the desert
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Thank you for sharing your 'floating-sauna-in-the-trees' Matthew. A real piece of artwork indeed.

I don't see a chimney stack in the photo?

I think your build should have its own thread as I'm sure there is lots you could share about yours alone. I know I'm interested in seeing more!
What a stench! Central nervous system shutting down. Save yourself tiny ad!
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