Vortex Stove

[Vortex]

Apr 11, 2023 3:13:53 GMT -8 Richarote said:

Hola Vórtice un gusto escribirle.
Soy un aficionado a la calefacción hace mucho tiempo vengo pensando en ¿como lograr juntar los beneficios de varios sistemas?
Las masa termica(de las rusas)
La rápida transmisión de calor y practicidad de limpieza(en los calefactores de hierro).

Concretamente mi pregunta es¿se puede diseñar una estufa de ladrillo y recubierta de hierro?
Perdón si no he sido claro en mi pregunta.
Y desde ya muchas gracias.

translation by Google:

Hello Vortex, a pleasure to write to you.
I am a fan of heating for a long time I have been thinking about how to combine the benefits of various systems?
The thermal masses (of the Russians)
The rapid transmission of heat and practicality of cleaning (in iron heaters).

Specifically, my question is, can you design a brick stove covered with iron?
Sorry if I was not clear in my question.
And in advance thank you very much.

Hola Richarote,

The Vortex stove is a brick stove covered with steel which heats quickly, stores heat in the thermal mass and is easy to clean. Look at page 20 of this thread to see the construction: donkey32.proboards.com/thread/703/vortex-stove?page=20&scrollTo=23834

La estufa de Vortex es una estufa de ladrillo cubierta de acero que se calienta rápidamente, almacena el calor en la masa térmica y es fácil de limpiar. Mire la página 20 de este hilo para ver la construcción:
donkey32.proboards.com/thread/703/vortex-stove?page=20&scrollTo=23834

Trev

[martyn]

Fresh new stove, I did not explain very well how the secondary air works (or doesnt) but I divided  the area between the fire box and afterburner into two with their own air supply, one to the vortex flame and one to the air curtain.

[Vortex]

Nice work again Martyn. I wouldn't expect the air curtain to burn with flame unless it's overfueling, as all the wood gas should be burned up before it gets to the front.

What's the size and directions of the secondary air around the port in this new model?

Trev

[martyn]

Trev, 15mm down each side but I want to reduce this to 10mm.

I bought two white smoke leak testers, they look like a big aspirin and cost me £3 each, I tried one in the fire box so we could see the smoke path but I did not get any video because the smoke only lasted a few seconds before it all got burnt away!
I lit the other one outside with my flame gun on top of a concrete block and it poured out white smoke like a Red Indian war signal, just shows how effective the stove is at burning smoke!

[martyn]

Still making changes as I go along…..

[Karl L]

Feb 3, 2023 2:16:26 GMT -8 Vortex said:

Hi Karl,

The top of the primary air slot is 14mm above the top of the threshold. The front of the threshold is 70mm back from the inside of the primary air slot. The mesh is just attached at the top by a few twists of copper wire so it might appear angled back in the pictures but it's meant to be vertical.

The threshold and mesh were all designed to deal with the issues that the primary air blowing on the bottom of the fire sometimes caused. The 275mm wide primary air slot right across the front directing the incoming air down towards the floor, probably reduces the importance of the size and position of the mesh and threshold, but that's just a guess at the moment.



This is how much it needs to be open for 20% csa primary (I use the tip of my index finger as a guide), so you can see how it directs the air downwards allowing it to then flow evenly up across the whole fire.

I can move this forward again now that I don't need the old stove to keep warm...

Trev, do you think it would work if I set the primary air slot a bit lower, so that the *lower edge* of the slot is just above the insulating sub-floor of the firebox - that is, 23mm below the bottom of the V-shaped floor in my 115mm design?

(The primary air slot would go through the steel shell of the stove, rather than through the door).

[Vortex]

Hi Karl, My only concerns with that would be ashes falling down in to it, you'd need to design it so they cant obstruct the air flow and can be easily cleaned out.

Also it might make the primary air go up the inside of the door glass rather than across the top of the fire, but you could add a ridge across the inside of the bottom of the door to direct the air towards the fire.

Trev

[masonryrocketstove]

This entire thread is pure gold. Trev deserves a medal. So does Martyn

[Karl L]

Hi Trev,
Where did you get hold of your airtight chimney damper?
Thanks, Karl

[Vortex]

Found it on ebay while searching for 'castiron stove damper'. I wanted one that was integrated into the collar like they use on cookstoves. It was a secondhand part, so unfortunately I don't know what it originally came off of. Had to import it from the U.S. at great expense, but it was perfect for what I wanted. Completely stops the leaking of the heat out of the mass via the chimney when the stove is fully out.

I wouldn't recommend it on a stove that is going to be used by anyone who doesn't know how to use it properly, as if it was closed during the coaling phase you could gas yourself with CO..
No one else ever lights my stove, I check the embers are completely gone before closing the damper and have a smoke and CO. alarm by the stove - So please be safe.

Trev

[Karl L]

Thanks very much, Trev.

I understand the implications of fully closing a damper, and not allowing people to use it who don't understand that.

I did quite a lot of searching for dampers a few months back, but didn't see what I wanted for a 5" flue. I may end up having to make something myself.

[Karl L]

I've got some 1400C dense castable and will make the wooden moulds soon.

I'm planning on using plywood for the base of the moulds, and ordinary softwood construction timber for the sides.

Also, I'll coat the insides with water-based mould release, as used for normal concrete.

Is it OK to use unpainted wood for the moulds, like concrete shuttering? Is there any problem with water in the castable mix getting drawn out by the dry wood?

I worry that this might reduce the water ratio in the mix, or cause the wood to expand and so move the castable mix as it cures.

[martyn]

You are far better off using sealed molds, apart from absorbing water, refractory sticks to virtually anything!
The easy way is to cover the wood with parcel tape before the parts are assembled.
If you want a really good finish then you can further coat the tape with a wax coat.
There are other important factors like mixing accurately with the right amount of water and mixing very carefully too.
Then we have a very fast setting time, so you need to be prepared with everything ready….
Then you need to vibrate the molds, it is very important to get this bit right and will make a lot of difference to the finished result.
Bare in mind you only have around 20 minutes from mixing to setting.
The vibrating is the only difficult part, it is simple in theory but vibrating can give a lot of different results depending on a few factors.
Timing is important as you want to get it done as quickly as possible with the least amount of actual vibrating!
It is easy to over work the cement and separate the aggregates into size groups which can weaken the result.
Also avoid vibrating twice with a time gap in between as the particles settle and start to cure very quickly so you dont want to break that process.

[Karl L]

Thanks Martyn, that's useful.

I was thinking to use a paint stirer to do the mixing, as that's what I use for making up mortar.

The datasheet says to use 11-14% water - I presume this is by weight...

For the vibration I was thinking to sit the mould on some white foam packing material, then put a coach bolt in a hammer drill and press this on the edges of the mould.

How can I tell when it's vibrated enough?

[Vortex]

I paint the wood of the molds with linseed oil and seal the joints with silicon. To vibrate I use an old corded drill with a U-bolt in the chuck, screwed to the bottom of a board sat on top of a car tyre. It takes more power than you'd think to properly vibrate a mold. Make the bottom of the molds the side you want facing inside the stove, as that always seems to come out the best, the top can be a bit dusty and doesn't seem to be as hard wearing. I would think that the 11-14% water is by weight - the 25KG sacks of castable I get say 3.5 to 5 litres of water, so 11-14% would be 2.75 to 3.5 litres. Add it gradually as you mix until it the right consistency.