4” vortex rocket cook stove.

I have just started to put together a 4” vortex stove, here are a few photos of the progress so far….

Hi Fox;  
You do beautiful work.
It will be fun to see how well a 4" burns!
Keep us posted as you progress.

Fox,

Would you please elaborate some on the materials you are using and its characteristics?  Much appreciated.  Thank you.

Hi Thomas, I am trying staying away from ceramic fibre products hence the use of vermiculite board.
The board I am using is rated to 1100c, I have used it many times before, it will show some spiderweb cracks after being super heated but seems to stay together for a long time.
The main issue is its lack of abrasion resistance however it will still last quite well if treated with respect.
I have coated all the exposed surfaces  with a water glass product that does give a little more protection.
On the plus side it is safe and easy to work with, it can be cut very accurately and fixed together with glue and screws.
Some guys have had their vortex stoves running for years at over 750c and the board is still going strong but I would not use it for a J tube fire box.
Having said that there are some very interesting Vitcas products that can be painted on to the board and they might work well for high abrasion areas.
It this case, the stove will not be used every day so I am not concerned about that aspect.
I did a little more today, I cut up a large cooker to get the ceramic glass out for the stove top, I made up the chimney exit and tried it in place….

Updated video….

I have a problem!
The 4” vortex rocket stove is running far to hot!
I need to calm it right down!

I did a few mods today, one was fitting  a piece of vermiculite under the chimney with a 95mm hole (the biggest hole saw I have) the chimney stack is 105 x 105 square.
I also fitted a step in the ceiling, that can be seen in the last few frames of the video.

I started the stove, top lit with a single fire starter block and the bottom door open, it was smoky for about four minutes and took about 10 minutes to get the vortex spinning nicely.
Then at 20 minutes I put the glass in place as the flame was going over the shelf but that did not stop it and the vortex was going like a mad thing. i left it like that, just running on the under floor air for 15 minutes but it was fast and furious running at 450+ on the hot plate!
I decided to remove the fire box glass and it really did take off in a crazy if not scary way!
Not in the video but I took a hot plate temp reading of 560c …. It was mad hot!!

New video update….. it is getting a bit out of hand for such a small stove!
The glass is being pushed to the limit!

A bit of an update….

Inside the vortex rocket stove, note just how compact the stove is and you can hear how the vermiculite has sintered into a hard surface …..

Love it  .that is my kind of cooking. Beautiful job on the buid.now I'm going to go smoke some chicken drumsticks. After watching the video it made me hungry. Lol

My second attempt at cooking a rotisserie chicken, much better this time with a more crispy skin.
The oven runs at around 460-80f for about one hour then it starts to drop off but was still 150f two hours after lite up.
In this case the inside of the chicken was 180f after 50 minutes.

Nothing beats a good home cooked meal. Especially cooked with a rocket stove. If I could only smell it cooking through the video

Lighting the vortex stove….

Last fire of the season and a couple of experiments ….

I have been experimenting again, this is the third video but quite an interesting one!

More experiments….

I think I might be getting somewhere with my secondary air experiments.

Now the prototype is connected to a bell, a bit of a basic put  together attempt but very  successful.

We are getting closer to where I want to be…

Getting near the end for this little stove….

There are two new videos on my channel, here is todays offering…..working a lot better than yesterday!

Your videos are excellent! Thanks for making them, and sharing the failures as well as the successes.. very helpful.

Is there a particular type of screw you use in the vermiculite?

I can't seem to find a source for Skamoenclosure glue here in the USA. Any suggestions for an alternative for gluing vermiculite?

Hi Jon, vermiculite is very porous so most high temp glues will work but to be honest, I used to glue every joint but now I try not to use any glue!
I worked out it is far better to allow movement of the individual components, so I pre drill a clearance hole in one piece and a smaller hole for the screw threads in the other piece. Then I dip the screw threads in the glue before screwing the parts together. Vermiculite is quite soft and as a rule you can only use the screw fixing once or in other words you cant take the parts apart and re screw in the  same hole.
Best to use stainless screws but as they will be in the middle of the board any hard metal screw should survive.

Also bare in mind that although vermiculite is fantastic for experimenting it will not be as durable or long lasting as some other refractory products!
There seems to be different grades as well, the one I use is much better than some others I have tried!

Where I live vermiculite is a very common product and sold in many stores, as is the glue and fixings.
In my part of the world,  most if not all new metal box stoves are lined with vermiculite!

Fresh new stove…..

Fantastic build Fox!
Keep experimenting.... love to watch your builds.

A little  bit more development…..

Hi James,

Any chance you can share the exact dimensions of your design, or point me in the right direction? I really like this unit because it is so small that you actually managed to put it inside a box!

Thanks Willem

Hi Willi, I am still working on the design but as a base working model you can find most of the dimensions here https://youtu.be/Bvw5RU1Gnvw

As always,  beautiful work Fox!
Thanks for sharing!

Fox James wrote:Hi Willi, I am still working on the design but as a base working model you can find most of the dimensions here https://youtu.be/Bvw5RU1Gnvw

Definitely let us know when you get a "best-of-breed" design figured out!

Also, maybe I missed it, but how did you cut the cermaic glass?

K Eilander wrote:Also, maybe I missed it, but how did you cut the cermaic glass?

Yeah I have a video for that……

Starting a new experiment with the 4” vortex stove…..

Always enjoy your experiments and great progress on the vortex stoves.

I have been wondering, but never read about my question being asked or answered, so here goes.

Fox,  if you had a burn chamber (over sized,  say a volume used for a 7" stove) But absolutely never filled past the volume of a 6" stove.  And had everything else sized for 6"   (air inlet-secondary burn chamber-port size-flue size)  Do you think the stove would behave properly?   I know this would use slightly more material in the build, and a person would absolutely have to resist over filling. But my question mostly is about it working great...or if this internal volume somehow effects how the stove works.

To me, this would be like filling a batch box or your vortex stove 1/2 full and lighting it.  But there might be more to it, that I am not seeing?

What would a person gain you ask? - just a slightly bigger door with a slightly bigger window for viewing, probably not much else. But both might be really prized, especially on the really smaller sizes. (4")

Scott I dont really know the answers to your questions, it would be great to try out all of your suggestions  if I could only find enough time in the day.
The 6” vortex stove is much bigger, I did build a 6” version a few years ago but it was too powerful for my use.
There  are still some fundamental  issues that I would like to address, one is the top viewing glass has a habit of smoking up early on in the burn, this happens more frequently if you dont neatly  stack nice dry wood.
This is not so much of an issue for me because  I know how to avoid it but it would be nice if the stove was a little bit less temperamental with less effort.
The main issue for me to work on addressing, is the length of time the vortex will spin before the flames die out to form coals.
So I have few idea about raising the  burning  wood higher up about half way through the burn time.
I have made a tray that has two positions  inside the fire box so I can see what happens if the fire is lifted nearer the vortex slot.
I dont think a bigger fire box will work very well as it will be tempted to over fuel but, there may be some leeway.
I will see how this year’s experiments go and what time I can find to spend testing …….

Well it works to a fashion….
Not ideal conditions with 18c air temp and zero wind but it fired up ok.
I need to do a lot of fiddling with the air supply  as it only works with no door at the moment, however the secondary air is very visible with the door in place!
For a first fire up with lots of mods, I think it went ok…..

So I made some changes, I think for the better but, of course one good run is not a conclusive result. We will continue tomorrow with some other ideas. Hopefully I will be able to build a more permanent stove with fresh glass and vermiculite but for the time being, we will struggle on with the bits and pieces I have to hand.

Another day another vid…..

The vortex stove has been developed mainly as a mass heater and like most ‘riser less’ stoves, it does not like being fed fresh wood on top of hot coals as the excess wood gas makes the stoves go into over fueling mode,  producing far to much smoke!
Even batch box designs as good as they are, do not like being reloaded too soon but, without a viewing window this fact is not so obvious.
Peter has developed a couple of stoves that can be re loaded more successfully and these use what could be termed as an ‘expansion chamber’
I had already worked than out that a much larger top box certainly helped but I am still struggling to keep a clean burn  going while continuously adding wood to a hot fire box.
However with a suggestion from Peter, I have adapted my own expansion chamber by utilising a different shape and position exit hole.
This has shown some good results but the side effect is a slightly lazy vortex shape and not very good heat distribution over the hot plate!
All the same this is quite exciting as I now have a better base to work from and hopefully I can adjust and tune the stove a bit more……