vortex stove 175mm

[Vortex]

Feb 4, 2024 3:55:29 GMT -8 willemdefilm said:

I there, I'm New to the forum but have been running a 130mm vortex stove for about 2 months now. I build it exactly to the dimensions as published by 'vortex' on the permies forum. I've read probably every post of vortex and fox and would like tot thank the a lot foe the effort they've made over the jears!! Very happy with our stove now, its hooked upto a water heating coil wit buffer tank feeding the underfloor heating, works the charm in our strawbale house. ( and yes I am fully 100% aware of the issues that come with heating water, expansion, steam explosions etc etc. Please don't worry)

Anyway I ran in to the same overfueling issues as jonasp explains in thjs thread. I tried different batches of wood (hardwood vs soft wood), different amounts of kindling and different sizes of wood, but kept having the same overfueling issues. The entire batch of wood be alight after 20 minutes and the afterburner just couldn't cope. At least that was my conclusion....

Then I took out the viewing window of the fire chamber and put a temporarily steel plate in with an adjustable air hole located completely at the top of the fire chamber. The idea was to be able to supply more/enough air to the vortex as this air runs along the ceiling of the firebox. Also this air would be directed more on top of the wood in the firebox, so the batch burns down top to bottom nicely, and prevent the wood to catch fire all in once.

This has made a HUGE difference in my stove, I can now even reload the stove while running whithout overfueling. I believe the stove automatically draws less air in at the bottom now since part of the draft is 'taken away ' by the new higher placed air inlet. 

Here a movie running on pine, hence the crackling and the sparks 

drive.google.com/file/d/1woF2sKNAozAcNqQ5oy9HMB-rPuq_4-Vw/view?usp=drivesdk

Also a picture where you cansee the air hole at the top in the door, in the movie I already had a cover over the air hole to prevent any sparks from flying  out.
drive.google.com/file/d/1wuAkFR35hs1P_Ak93XIVTkj9lburwiLM/view?usp=drivesdk

Perhaps sharing this can help others.

I can see it now. Looks like a perfect clean burn.

What is the layout of the primary air supply at the bottom of your door? It's important that it is not blowing on the base of the fire, as that will drive it faster and cause the fire to burn down towards the source of the air.

My primary air inlet is at the bottom of the door, the full width of the firebox, with a diffuser mesh on the inside, and a threshold behind it about half the height of the inlet, so about half of the air gets directed upwards behind the glass.

By the way I don't think I've ever posted anything about the Vortex stove on Permies, so what you saw must have been by martyn (fox).

[willemdefilm]

Hi vortex, 

Then it  must have been this forum after all. Its this 90+ pages thread about vortexstove that inspired me initially. 

The primairy air comes in through the doorframe about 3/4 at the bottom of the doorframe and 1/4 through the sides. Perhaps the bottom air stuffed me over if I think about it now.  Our house is build airtight with heat recovery ventilation So the whole stove was designed to be hooked up to the outside air supply, didn't get that far yet.... At the moment we just open the window works just fine. 

I'm planning to build a new stove later this year and will be looking for advise then via the forum so hopefully you will allbe around then.

[jonasp]

willemdefilm
That's wonderful to hear! lately the overfueling doesn't happen that often anymore since i pack the wood more tightly and the fire spreads more equally and if it occurs it's fixed by giving it a bit more air.
I have been thinking about making a hollow frame that would let the primary air come from side and top. The setup that Peter uses in his DSR 3 stove. Showing your stove having the same issue and fixed it by the primary air placement only reinforces that.
What % csa primary air do you use for your setup?

Looks like a really well built system, do you have any more photo's you want to share?

Thanks for sharing your results willem!

[willemdefilm]

Hi Jonasp,

I have attached some prints from the 3d program I used. This contains more info then making pictures of the finished stove. Unfortunately I have not taken any pictures during the build. 

Some more info:

The oven gets around 400C during peak operation of the stove, this is officially a black oven as the exhaust gasses pass through it. Fortunately I is never black on the inside, and there is a  long period on the end of a batch where the stove stays a 200-250C for at least 2 -2,5 hours.

The outside of the stove was planned to be faced with tiles, but unfortunately the outside facing expands/contract to much to do so. This is due to the fact that I have mounted these plates to the steel frame, which wasn't to smart to be honest....

The off-gass temperature (chimney temp) is currently between 150-190c which is too high for my liking. The new stove will have to have more heat exchanging surface to get this down to about 100c. Nevertheless I'm quite impressed with the simple corrugated stainless steel pipe that is currently in there. The main downside is that it is impossible to clean out, as the tube is coiled in there relatively tight. I basically got this idea from this guy. Great couple of video's he's made about it. youtu.be/NdAP8BdBz6o?si=3zfq7-yL4w3rKvYw
  
At the moment I manage to get 60% of the KWH in the wood of a batch into the water If i burn 10kg of wood. The outside of the stove itself will get then to about 60-70C  and the whole thing ways around 200kg.  The firechamber itself will still feel warm inside after 10 hours.  The rest of the energie goes probably through the flue at the moment. 

Last thing to mention is that I have the stove sitting on hinges (top and bottom) in the corner of the wall so it seems to float from the ground, and this means the firebox is higher so you don't have to bend so far down. The reason for the hinges is that I can then swing the stove out of the wall, where i can then open the top to clean out the heat exchanger space. 


drive.google.com/file/d/15tpOx29MroT2BIpZ4y2gOJRJqm_lRx1J/view?usp=sharing

drive.google.com/file/d/1OUPPJvytaYud0r3W7rjrwh3N_8-xyjVR/view?usp=sharing

drive.google.com/file/d/1X15MKV3PshHyCarNRnWCmeQsmariF4ap/view?usp=sharing
drive.google.com/file/d/1YNyJTNweqIdwHtv-GXUJmDJVoMkvHOlJ/view?usp=sharing

[jonasp]

Hi, Thanks for the extra information. Super interesting project!
The off-gass temperature you're talking about is that the warmth you collect through the heat exchanger?
You're youtube link is a wrong video.

You get clean very warm burns as to not have a real black oven, that's awesome to hear. My white oven (now a bit brown, my gf forgot the cherry pit pillow in there) get's around 200C and then 10hours later it's still above 100C. I need to get a infrared thermometer to get more accurate readings.

Really nice well made stove you've built.

(I speak dutch but I'm from Belgium, I already thought you were from the Netherlands hehe)