Polytunnel rocket stove - finished!

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Leigh
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Re: Polytunnel rocket stove - finished!

Post by Leigh »

Have a good look through YouTube lots of Vid's to watch on Rocket heaters and there are a good few eco forums out there to give you lot's of Ideas
Leigh
flounder

Re: Polytunnel rocket stove - finished!

Post by flounder »

from what I gather, the use of a metal drum as opposed to a brick structure is one of both economics and practicality. An old oil drum being cheap and heating up quickly meaning you have more instant heat for say, boiling a kettle.
The construction of a masonry heater may take longer to heat up but will be a good thermal mass for releasing heat for longer........plus you could make a wicked pizza oven icon_thumleft
Carl

Re: Polytunnel rocket stove - finished!

Post by Carl »

Mmm - pizza oven. :D You can build these for cheap too if you're a good scrounger. Here's my blog on the one I built - http://fornoeconomico.blogspot.com/. You can see my polytunnel in the background of some of the pictures!
nige pook

Re: Polytunnel rocket stove - finished!

Post by nige pook »

Absolutely chuffin brilliant Carl,well done! icon_salut Just need you to pop round here and build one for me now having built a reasonable polytunnel! Unfortunately I dont fully understand it having not researched it like you seem to have done and have opted for a double parasene burner for the time being. Damn bitch to get going properly without flaring up and smoking :evil: for the first time,think it's sorted now though :roll: How the little mac doing,assume it was you who popped up for the alocasia?Nige
HarryandNess

Re: Polytunnel rocket stove - finished!

Post by HarryandNess »

WoW! Have only just seen this and it's brilliant! You clever thing! Keep us posted and good luck icon_thumleft icon_thumleft icon_thumleft
Carl

Re: Polytunnel rocket stove - finished!

Post by Carl »

Hi Nige - the Alocasia's doing great, romping away on the windowsill in the main room. Put out a couple of new leaves in the last month, so I think it's happy. Hope your collection's all OK. When I'm starting the fire off I get some good flare ups too - tonight was interesting due to the gusty wind. Gusty winds turn the polytunnel into an enormous set of bellows - the wrong gust and you get a face full of smoke!

Having a fire in the polytunnel every couple of days now - now firing it on split ash logs. It will burn two 2" diameter ash logs in about 40 minutes, so I've been doing longer fires of 3-4h, only popping out 4 or 5 times to refuel. It's kept the fleeced plants at about 5-6C most of the time, in the face of -2C and -3C nights. I think that the best strategy is to have a long fire and build up a good store of heat in the soil, but I've still got a lot to learn.
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Arlon Tishmarsh
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Re: Polytunnel rocket stove - finished!

Post by Arlon Tishmarsh »

One of the best woods to burn there Carl, the ash. I was out cutting and splitting ash yesterday ready for the woodburner for xmas. Lovely stuff icon_thumleft

I was wondering, i've watched loads of vids on these burners and no one has come up with some kind off hopper at the intake. I was thinking , when burning thin stick, is not poss to fabricate something out of mesh or metal to form some sort of inverted "road cone". That way it may be possible to put longer stick / thin branch about 3 ft long as opposed to short branch. Less running back and forth to refuel. When burning more in the way of log, just lift it out of place.
flounder

Re: Polytunnel rocket stove - finished!

Post by flounder »

Arlon, thats what my one will have for longer sticks when I eventually get the thing finished
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Arlon Tishmarsh
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Re: Polytunnel rocket stove - finished!

Post by Arlon Tishmarsh »

Seems to make sense to me Flounder. Its ok when its in the house, where these burners seem to originate from but running back and forth the greenhouse is only good for working of the ale and sherry trifle at xmas. :lol: :lol:

How's your's progressing, love to see whats happening icon_thumleft
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Leigh
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Re: Polytunnel rocket stove - finished!

Post by Leigh »

Hoppers a good idea but be careful the Wood in the feed does not catch fire Have seen this in one of the forums i read about them on I'l try and find the link.


Meanwhile Google.

Rocket Mass Heaters and articles on permaculture
Leigh
flounder

Re: Polytunnel rocket stove - finished!

Post by flounder »

Arlon Tishmarsh wrote:Seems to make sense to me Flounder. Its ok when its in the house, where these burners seem to originate from but running back and forth the greenhouse is only good for working of the ale and sherry trifle at xmas. :lol: :lol:

How's your's progressing, love to see whats happening icon_thumleft
Its progressing slowly :roll: I came down with severe man flu last week and the thought of being head down ar@e up working in the cold snotting up the greenhouse put me a bit behind :D
I've completed all but the insulated chimney and when thats done I'll assemble everything and yes with pictures icon_thumright
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Chad
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Re: Polytunnel rocket stove - finished!

Post by Chad »

Carl,

Where the drum gets hot is there a problem with stretching [in the extreme - melting] of the poly tunnel above it?

I'm very impressed with the design and your building of it.

If all goes well I should have a tunnel next year and am almost inspired to try something similar. If only I wasn't as lazy as I am!

Chad.
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Arlon Tishmarsh
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Re: Polytunnel rocket stove - finished!

Post by Arlon Tishmarsh »

flounder wrote: Its progressing slowly :roll: I came down with severe man flu last week icon_thumright
Ah yes, man flu. Enough said. Obviously something a women couldn't begin to comprehend but to other men it's all life's evils wrapped up into one nasty illness ,....

soldier on dude icon_salut

:lol: :lol:
Carl

Re: Polytunnel rocket stove - finished!

Post by Carl »

Yes, the hopper thing sounds like a good idea, if someone could find a a way to pull it off. The big problem is that the feed hole (and hopper) can't be too deep, or it starts acting like a chimney and the wood in the feed chute then burns up, and the direction of the fire reverses! I read about this somewhere - might have been the forum that was mentioned earlier. It seems my rocket stove does take a bit of effort to keep it well fed.

The polytunnel roof doesn't even really get warm - by putting the fire so far underground it's the soil that gets warm, not the polytunnel air. There's little point heating the air in a polytunnel, as the plastic offers minimal insulation and lets all the air heat out quickly. The big advantage of the polytunnel is still air, meaning you can easily trap ground heat around plants using layers of fleece.

For example, I started a fire about 4pm today, and using bigger ash logs I have to pop out every hour or so now to refuel. I'll stop in about another half an hour, and let it burn out. Ash is pretty much the best firewood, I also like oak if well dried (but then I'll also burn any old stuff from the workshop, so long as it's not been treated). The air outside the polytunnel right now is -1C, the inside of polytunnel is 2C, the air under the fleeced plants, two foot above ground is 4.5C, and the soil in the centre of the tunnel is at 9C. The ground outside is iced over... :(
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Arlon Tishmarsh
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Re: Polytunnel rocket stove - finished!

Post by Arlon Tishmarsh »

Carl wrote:Yes, the hopper thing sounds like a good idea, if someone could find a a way to pull it off. The big problem is that the feed hole (and hopper) can't be too deep, or it starts acting like a chimney and the wood in the feed chute then burns up, and the direction of the fire reverses! I read about this somewhere - might have been the forum that was mentioned earlier. It seems my rocket stove does take a bit of effort to keep it well fed.
(
Thats why i originally thought about some sort of mesh cone so it would not create a chimney effect but then with thin branch it could raise another issue of snagging. Then i thought, if the brick intake is about a foot perhaps an upright rod with a just a few wide circular holding rings attached (horizontally) at about every foot, then you could put thin branch about 3 to 4 foot long inside the holding rings but not tightly packed. As the bottom of each bundle of branch / stick burns it drops down under self weight and feeds the fire at the same rate it would burn anyway.

I did see a vid where a guy coupled a woodburner to the rocket box. It worked but not as good. Problem is you have to different types of burn methods i.e the rocket box where you want quick fast high heat burns and the woodburner where you want a slower ember fire and as little flame as poss
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