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Post by treelyruly on Mar 4, 2017 23:23:03 GMT -8
hello all, I am looking to cover my rocket stove in an cast aluminium water jacket, as a replacement for a barrel. I just learned sketchup today, sorry its a bit rubbish. upload photoNot shown are the inline pump, radiator, and storage tank. water will flow from tank, to pump, to waterjacket (in bottom, out top), to radiator, back to tank. tank will be open. total pressure in system will be 100kpa. I am assuming that by the time the exhaust reaches the top of the insulated burn chamber that combustion will be complete, and that i wont need to insulate the top of the barrel (inside) to prevent overcooling the exhaust. desired waterjacket temperature will be 30C to 90C at the top of the barrel. desired exhaust temperature is less than 60C Will i achieve these results? will i get the exhaust down to less than 60C or will i need another bell/barrel? Thanks
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Post by Dan (Upstate NY, USA) on Mar 6, 2017 2:43:23 GMT -8
The aluminium will melt and break at the top and put out your fire.
And I don't know how anyone could cast a jacket like that. Maybe a welded tank, and that will cost you a pretty penny...
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Post by coisinger on Mar 7, 2017 4:29:49 GMT -8
Aluminum has no place in a rocket stove, in my limited humble opinion. If you have no other option to heat water, or if you are using this as a test bed of some kind, a rocket stove is really not the best way to do it.
As wolf stated, aluminum has a melting point of about 1200 degrees F, it become malleable at approximately 500 degrees F. Considering your sketch-up has direct contact to the riser gases, this arrangement is likely to fail much sooner than later, even with constant circulation of water.
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Post by peterberg on Mar 7, 2017 5:02:02 GMT -8
As long as the water isn't boiling, the temperature is too low for the aluminum shell to melt. Above the riser is another matter, this need to be insulated on the inside or the water need to be pumped around with consideral speed to prevent the water from flashing to steam. Steam flashing is bloody dangerous, even an open system won't be able to vent a 1600 times expansion through the relative small diameter pipes within a split second. So the alu water jacket will explode and blow off the roof.
A safety valve can be dangerous too, when activated it will blow high-pressure scalding hot steam. So the valve shouldn't be in the inhabited part of the house in my opinion. Me personally, I avoid heating water with wood stoves as the plague. What happens when you constructed the whole thing with a pump, safety valves and whatnot and during the top of the burn there's a power outage, for example?
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Post by drooster on Mar 7, 2017 10:15:04 GMT -8
Maybe the OP already has a cast aluminium water jacket and wants to use it.
I see a lot of interesting water jacket 'tubes' at my favourite scrapyard, some in stainless steel, some aluminium ... I'm sure there is a way to safely install it, but I myself would rather use an off-centre larger water tank which can be adjusted for position by rebuilding rather than surrounding the riser ... it just seems like asking for trouble in the OP's illustrated setup.
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Post by pinhead on Mar 23, 2017 7:16:38 GMT -8
If I were to build it, I'd leave the top completely open and extend the sides much higher - to form a "pool" above the riser instead of an enclosed container. At the very least there should be a large reservoir above the riser - in an effort to prevent flash steam.
Is this for drinking water or shower water?
Ever heard of Legionnaires' disease?
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Post by madden9 on Jul 23, 2017 1:43:02 GMT -8
Just keep the updating.
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eng
New Member
Posts: 18
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Post by eng on Aug 29, 2017 0:50:30 GMT -8
I like the idea of a rocket stove for heating water. I have not made a r.s. water heater but have made down drought wood burning water heaters which work with thermosyphone to a 200 Litre storage tank before the hot water is distributed by thermosyphone or pumped using small bore plastic or copper tubing. You will need to do some homework before you start. Modern home heating books will tell you about small bore systems, old text books (1940's to 1970's) thermosyphone systems. Some of the schemes, that hopeful people, on this site have dreamed scare me. Open vented systems are best for wood burning boilers where they cannot quickly be shut down when the power to the circulating pump fails. I trust books from the library, I treat the internet with care and suspicion. Your aluminium water heater could work but you will have get advice on water treatment from a water treatment firm who provide water treatment chemicals and advice for boiler systems. I would build it of mild steel as I have always done. If you are not a good metal fabricator get it done professionally. I would insulate above the riser with a good fire brick slab. I supervised a 4 m.w.wet back steam boiler used for heating a small military training camp. For several hours on cold frosty mornings I ran the back end temperature of 1100 deg C. In ten years no damage was sustained. It can be done. Go carefully.
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Post by apollokit on Nov 2, 2017 9:12:07 GMT -8
Aluminium maybe not but stainless steel yess. Here's you have some example of water jacket which I finished buid some time ago: I wrote a reply in this post: donkey32.proboards.com/post/25619/threadIt's: 1.4307 AISI: (304L) DIN: X2CrNi18-9 if you want to know
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