Rocket Powered Sauna!!!

Greetings!

I've been lurking on this forum for well over a year, and happened to discover it shortly after deciding to finally build an outdoor sauna. After a half-dozen odd mockups/prototypes/screwups, I have an authentic Finnish "sow-nuh" (please don't say "saw-nuh") that is heated by a 6 inch batch box rocket heater. Much to the disbelief of my patiently skeptical wife and amazed children, it works!

Some pictures...

can't feel clean without a sauna, myself. how about some specs? what size room, how long to heat up to what temperature, how's the löyly, &c.

That's gorgeous! Congratulations!

Please more details. This is on my dream list to build and I hope to start on it next year. I keep running through my head on how to do this with a rocket stove and haven't been able to come up with a way.

This thing's awesome, tell us more! Do you have any build pics, specs, please do share!!!

Very nice - on my 2 do list. Specs? Build pics? Cost?

Would love to hear more. Thanks.
Good work, Paul.

Beautiful! I would pay for detailed building plans and specs. This is something my wife had been after me about for ages. This would be perfect.

Thank you all for the nice comments. Here is how it went... I grew up with an electric sauna, and my wife and I always intended to build one once we had some acreage. I began the project in 2014, but didn't want to spend the money for an electric heater right away (I'm quite cheap). Inspired by my wife finding me an arc welder at a garage sale, I began to look for a way to build a simple wood heater as purely a temporary step until I could find a good deal on an electric unit. Right about that time I happened on a link to a RMH article and the gears began turning. Fast forward through lots of reading and many prototypes and design changes... here we are.

It honestly works far better than I believed possible. To answer Tel specifically: The overall building is 16 x 8 outside dimensions. The steam room is 8ft 5in x 7ft 3in inside with a 7ft 3in ceiling, so large for what I am used to.

I have had it up to 210F, but the stove body kicks off a lot of radiant heat - making the walls and benches uncomfortably hot to the touch. We have found that 160-180F feels really nice. What I am really happy with is the heating time. The other night it was 160+ about 40 mins after lighting the fire. That was with a load of alder and oak. I have been burning lots of random wood (pallet pieces, cottonwood, unseasoned branches), so around an hour is pretty common.

Cost: We are still tracking some things, but it will honestly top $6,000 before it's done. That was with sourcing as many discount materials as possible and doing all labor myself. There are certainly places I could have shaved costs, but I found out simply building a watertight outdoor insulated buildng is expensive.

Plans: No plans, sorry. I came up with the overall dimensions and just went with it. I will try to answer any specific layout/dimension/construction questions though.

More pictures as I dig them up!

Paul Daniels wrote:
I have had it up to 210F, but the stove body kicks off a lot of radiant heat - making the walls and benches uncomfortably hot to the touch. We have found that 160-180F feels really nice. What I am really happy with is the heating time. The other night it was 160+ about 40 mins after lighting the fire. That was with a load of alder and oak. I have been burning lots of random wood (pallet pieces, cottonwood, unseasoned branches), so around an hour is pretty common.

my own rocket kiuas also puts out a lot of radiant heat. when I rebuild it, I think I'll put some sort of shield around it to reduce the radiation and increase convection. I like a sauna in the vicinity of 240 °F on the top laude, but when I'm up to that temp, the surface of my kiuas is close to 800 °F and looking at it heats my eyes up. I like to sweat, but I don't think hot eyeballs are desirable.

Found a few pictures on my phone of the stove construction.

Tel, I also have thought about the heat shield idea. I may go that route if we decide to try pushing the air temps up. Right now anything much above 180F and my kids complain about it being too hot

Looks like a really nice stove/sauna heater. Did you follow any plans/thoughts on how to build the batch box? I like the idea of a rocket stove but the places I would want to use it are less frequently used so having the ability to heat longer on one load of wood would be really nice.

Paul Daniels wrote:...
I have had it up to 210F, but the stove body kicks off a lot of radiant heat - making the walls and benches uncomfortably hot to the touch. We have found that 160-180F feels really nice. What I am really happy with is the heating time. The other night it was 160+ about 40 mins after lighting the fire. That was with a load of alder and oak. I have been burning lots of random wood (pallet pieces, cottonwood, unseasoned branches), so around an hour is pretty common.

More pictures as I dig them up!

I'm thinking a nice water jacket on the face of the stove would be an ideal solution. Can your welder handle that?

Thanks for sharing Paul. I truly appreciate it as my partner and I are in the design stages of something similar. I can't tell from the pictures how high the heat riser extends into the top chamber containing the rocks. Also does the stove vent directly after heating rocks? Have you added any heat shield since last posting?

Thanks

Wow, I am looking for ideas, this is very straightforward.i want to build more of a traditional banya. With sod roof, but want the heat source to be super simple.

I’m liking this. My wife and I want to build a sauna eventually and have a bunch of red pine to work with now. Will probably want cedar for the inside, unless I find out whether or not charred and sealed red pine paneling would hold up to the heat and moisture. Definitely want to heat with a rocket stove but know very little about them and have no experience building and using one at all. This is inspiring though!

Hi Brody;
These folks have built a batchbox rocket stove for their sauna.
A longer burning more technical design that allows you to use horizontal wood.
There are some metal parts that need to be fabricated  to build a batchbox.
They are readily available from my store https://dragontechrmh.com/

But as a new aspiring rocket scientist, you might find that an 8"  J tube rocket is much easier for you to build, with no metal fabrication needed.
Simple J tube practice rockets can be built in your backyard.  
Learning about them ahead of time will make you very confident when you go to build your sauna.
After you have built and used a J tube in your sauna then upgrading to a batch box for longer burn times might be to your liking.

To practice build/play all you need are some clay bricks and gooie clay like mud.
If your interested we can give you the dimension's you want to work with.
Also finding a copy of the Rocket mass Heater builders guide is a great starting point that will answer many questions.

thomas rubino wrote:Hi Brody;
These folks have built a batchbox rocket stove for their sauna.
A longer burning more technical design that allows you to use horizontal wood.
There are some metal parts that need to be fabricated  to build a batchbox.
They are readily available from my store https://dragontechrmh.com/

But as a new aspiring rocket scientist, you might find that an 8"  J tube rocket is much easier for you to build, with no metal fabrication needed.
Simple J tube practice rockets can be built in your backyard.  
Learning about them ahead of time will make you very confident when you go to build your sauna.
After you have built and used a J tube in your sauna then upgrading to a batch box for longer burn times might be to your liking.

To practice build/play all you need are some clay bricks and gooie clay like mud.
If your interested we can give you the dimension's you want to work with.
Also finding a copy of the Rocket mass Heater builders guide is a great starting point that will answer many questions.

Thanks for the advice! Our sauna is kind of low on my priority list right now (although my wife would rank it more highly!) but I will probably the Art of Fire and maybe some more of the Wisner’s work before getting too involved. Our boiler for our house is on its way out and I’d like to heat with wood instead. Hopefully in the future we will have a RMH for the sauna and one for the house to double as a cook stove as well! In the mean time, I do have old clay bricks and a decent amount of clay in our soil at home. I’m thinking a good practice run/experiment will be to build a small rocket stove and boil maple sap in the spring. Maybe cook a few meals on it to see how it goes before invest information serious time and effort into something more important!

Hi there,

nice and very interesting. I´m planning an rocket stove for my new outdoor sauna at the moment. I´ll do it almost like in the "Rocket mass heater builders guide". First of all i thought about "will it work"? Enough heat on the top for the sauna stone? Here i read, that it should work.

Now i´m a bit irritated: At the rocket mass heater builders guide there is always an much smaller vertical feeder. On this thread its much bigger an horizontal. Do i need this big feeder? Maybe the dimensions of the guide would be wrong with this big feeder?

2. Question: Does it actually make any sense to build an "Mass" inside the sauna with the exhaust pipe?

3. Question: Should i place the feeder inside oder outside the sauna?

Thanks for your help!

Regards,
Benne

Hi Benne;
I'll see if I can explain.
A sauna with a rocket stove would not need much mass at all.
The feed tube should defiantly be inside the sauna with you and not outdoors.
You'll want to enjoy the visual beauty and hear the dragon's roar from a J-tube RMH
As far as size.
Common is 150mm  and more popular for home heating is a 200mm
Smaller than 150mm can be hard to operate.
There are size parameters on J-tube construction that we will happily supply you with if needed.
Be sure to take pictures and write a post as you build your sauna.

Hey thomas rubino,

before i continue: sorry for my bad english, i´m from germany.. O:-)

Thank you very much for your informations. Now i know, that it will work as a sauna. I think, there will be no mistake if a make a little mass at the exhaust. Saving a bit energy :-)

So, it will be the best way to put the feed tube to 200mm. I´m thinking about to do the feeder and burn tunnel out of square firebricks. The heat riser as firebrickpipe. Or would it be better with classic "burned" bricks?

Now i will start planning. As you wished, i could make an new thread for my stove. Starting at the planning from now. I think there would be much discussion for the solution here :-)

Regards,
Benne

thomas rubino wrote:Hi Benne;
I'll see if I can explain.
A sauna with a rocket stove would not need much mass at all.
The feed tube should defiantly be inside the sauna with you and not outdoors.
You'll want to enjoy the visual beauty and hear the dragon's roar from a J-tube RMH
As far as size.
Common is 150mm  and more popular for home heating is a 200mm
Smaller than 150mm can be hard to operate.
There are size parameters on J-tube construction that we will happily supply you with if needed.
Be sure to take pictures and write a post as you build your sauna.

Do you think you could heat both the sauna and the change room by running duct through a mass in the change room before going back to the chimney? Would that take too much heat away from the sauna room? We live in a cold climate. I was thinking that in the winter it would be nice to have the change room heated too.

I wouldnt do that because i dont build an changeroom. I could inform you about the heat, maybe it will be enough. At the moment im prepeaeing the ground for the fundament.