Vortex Stove

[marcios]

interesting, what materials are used and how is the route between the upper chamber and the chimney?

[Vortex]

The firebox is made of standard 9" x 4.5" x 3" firebricks.

Roof of the firebox / floor of the afterburner is 3/4" / 20mm vermiculite board scraps.

Afterburner sidewalls are 9" x 4.5" x 3" Insulating firebricks.

Roof of Afterburner / floor of top chamber is 3/4" / 20mm vermiculite board.

Sidewalls of the top chamber are 9" x 3" x 3" Standard firebricks.

Hotplate on top is 8mm mild steel.

Glass is 2 pieces of 10.5" x 9" ceramic stove glass.

Chimney is 4-15/16" / 125mm stainless steel about 4' / 1.2M high.

Flue gases just exit from under the rear of the hotplate into the bottom of the chimney, the 90 degree transition is made with some standard firebricks and a bucket of the local clay slapped around it to make it gas tight. Firebox also smeared with a bit of clay to seal up any small holes.

All the materials were here from previous stoves and experiments. Took me about 2 hours to mock it up and then put it together.

[peterberg]

Scalability is a good sign, it shows the design relies on laws of physics. In your case it means the thing could be larger overall as well but that wouldn't be practical for to cook on. Maybe a larger firebox and twin afterburners and top chambers?

Along the lines of a batchrocket variant recently built in Argentina. One big 25 cm (10") system firebox and two 17.8 cm (7") diameter risers. Built as a double sidewinder sporting four 200 liter barrels and a big box behind the firebox to balance the thing. Alex Groe claims it burns quite well, no smoke at all although regrettably there hasn't been any Testo near it so far.

It would be interesting to see how a Vortex stove would work following the above. Especially while both the afterburner chambers were in full sight!

[Vortex]

A double double vortex would be a sight to see! I guess there could be a port on either side of the firebox roof, that would give enough room for both of the afterburners and top chambers side by side.

The Argentinian Double Sidewinder sounds amazing, are there pictures of it online anywhere?

I thought double risers or channels tended to favor one side or the other, how does the 'big box' balance it? If it's running full tilt I can see it'll fill up all routes that are available to it, but I would think it likely to be less efficient or clean burning when running at a lower level as the heat and turbulence would be divided between the 2 ports and risers.

[peterberg]

Here's a short video on Facebook. www.facebook.com/alejandro.groenenberg.3/videos/10157330609787927/

I've seen some pictures but I can't remember where. As I understand it, there's a big box behind the firebox and underneath the barrel towers to balance the chimney draw between both risers. The exit to the chimney is low in the rear wall. The builders were well aware of the balance issue and even prepared for an option to use a 25 cm chimney pipe high between those barrels. But the thing ran fine as they mentioned so they'll wait until it's completely dry before reviewing the results.

As for the running at lower levels: this is a biggie, firebox being 36 cm wide, 54 cm high and 72 cm deep. About half of this volume would be a full batch which comes down to 0.07 m³. At a specific weight of 600 kg/m³ that would be: 42 kg for a full batch, 8 times as much as in my own 15 cm system! Running at a quarter of maximum batch would still be 10 kg.

[bbdoc]

Feb 13, 2019 14:59:53 GMT -8 peterberg said:

Feb 13, 2019 13:20:32 GMT -8 Vortex said:

To give credit were it's due Peter, your work on the DSR did encourage my existing plans to experiment with a port in the roof of my firebox, but seeing that video docbb posted in 2013 was what really inspired me, and I don't remember you giving him any credit either

So I am supposed to give credit to someone who posted a link? Are you serious?

A very long thread in russian language in fact and some other ones in other forum (also in russian)

[Vortex]

Hi Doc, Good to see you back here.

I read through that thread a few years back - and it's now up to 246 pages! I just read the newer posts. It's hard to understand the machine translation of technical discussions, but mainly there I see a split between those who favor a clean burn and those who don't think it's worth giving up the oven for it. If I remember correctly the earlier part of the thread talked a lot about whether the 'Furnace of the Ancient Aryan's' even existed, and if so in what form.

Did I miss anything important?

[martyn]

I have also had a good go at that thread too, really frustrating that i cant understand the majority of the text, i have spent hours pasting pages and using a translator but the photos and diagrams do show a lot anyway. .... very interesting .

[cork]

Hi Trev,
Can you remember the grog to cement ratio you used for casting mix ? I understand you moved the shelf above the afterburner back from the glass from 3" to 4.25" to reduce etching of the glass. I was wondering if I was prepared to accept some etching or even make a little bay window frame for the glass would this give the stove a larger operating "sweet spot"? Thanks for your help. James.

[Vortex]

Hi James,

The grog to fondue cement ratio is 4 to 1.

Not sure about a 'bay window', probably be OK if the window is the full width and height of the afterburner and top chamber, as that would behave the same as if they were that size on the outside. 4.25" (between the inside of the glass and the shelf front) seems to be the sweet spot between the glass getting etched by too much heat and getting hot enough to quickly burn off any smoke residue from the startup.

[Piet]

Hi Trevor.

I've been following your vortex stove for a long time. For my pizza oven I went for Matt's riserless but for our cabin/backyard office I want to give your stove a try. I did a dry stack mock-up and it burned amazingly. I'm gonna a build a 130mm system with the smallest footprint possible, just enough mass not to waste all precious heat but light enough not to break the wooden floor and to be a 'quick' system in terms of quick heating the room after startup. I'll keep you posted as I go.

Your 2 sketches are all I need to get started but I am not sure about the amount of air. Was that 20% of the csa? Can't find it easily.

Cheers!
Piet

[Vortex]

Hi Piet,

My 6" / 150mm stove in the house  has 20% CSA air, which consists of a 20% csa primary air inlet reduced to 10% by an expanded metal screen (the screen keeps sparks from jumping out, but also shreds the incoming air which really seems to help mix it with the wood gases). The other 10% is all around the sides of the door (there's a two position door catch so it can be completely closed or held open with a 2mm gap all around the edges). It runs better like that than all 20% via primary.

If I was making it now I would increase the maximum available as it occasionally needs a bit more if you're burning a lot of small wood, and I'd probably make something like Peter's latest system where it comes in around the sides after being heated through a box section door frame.

The 4" / 100mm stove outside needed a fair bit more than 20% air. I was using the glass propped up and leaning slightly out at the bottom so cant say exactly how much it was. I would make it adjustable up to 40%. It's easy to see when you have it right as the double vortex will be completely formed in the afterburner. Too much air and you'll just get a fire fountain, too little air and the flames will stream out of the afterburner around the shelf and up under the hotplate.

Look forward to seeing your pictures
Trev

[scotsjohn]

Hi vortex, I am new to the forum although I have been reading about your design for some time!
I am very tempted to have a go at building a 4” or 6” system just to use as a cooking stove in my summer house.
I love the fact you have some visual experience with your designs, that aspect has been putting me off from building some of the other designs but yours looks so cool.

[Vortex]

Hi John,

Yes it's great to be able to see the secondary combustion in real time, it really helps you learn how to stack and run the stove for the cleanest burn.

If I was building a purely cooking stove version I think I would use a ceramic cooktop. That way you'd get more instant heat where you want it, as the thick steel top slows down the heat transfer a lot, which is great if cooking is not the stoves primary function and you want most of it to go into the mass.

Post some pictures here if you get around to building it.

[scotsjohn]

I have been collecting bits for a year or so and i do in fact have a ceramic hob, also 10 X 1600c insulating bricks, one half sheet of ceramic fibre board and 4 25kg bags of 1200c refractory casting cement , all bought as used from ebay !
I might need quite a few more bits but being a Scot I will wait for the bargains.