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Post by josephcrawley on Mar 3, 2015 15:52:43 GMT -8
I have been thinking of incorporating a water loop in my rebuild. I would like to run the water through a few radiators and back to the stove. Looking at old non steam systems they had an expansion tank at the top of the system with an overflow. If that top tank was open at the top wouldn't this keep steam pressure from forming? Any thoughts
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gjh42
Junior Member
Posts: 61
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Post by gjh42 on Mar 10, 2015 9:27:48 GMT -8
It would keep steam pressure from building up, but it would not stop steam flashing in heat exchangers, which might or might not be a problem depending on how strong the piping and equipment is and how easily the expansion can reach the open-air tank. You would still have to allow for steam/hot water bubbles/splashes and keep them away from possible human contact.
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Post by josephcrawley on Mar 11, 2015 10:46:20 GMT -8
I had envisioned a hot water heater tank at the top of the system with a chopped top which would allow steam to escape and facilitate filling the system. Of course I would need to verify the system was not getting to low on water now and again. I wonder how much pressure steams bubbles would create. As they say hard saying not knowing.
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Post by Donkey on Mar 12, 2015 7:08:56 GMT -8
When water turns to steam, it expands about 1000 (one thousand) times it's original volume. The pressure this can bring to bear outstrips any material that we (the common man/woman) can get our hands on. As long as that expansion has an easy place to go to, you've got no problems. Be aware that if you have hard water, boiling it in a tube will create calcium deposits on the inside of the tube, narrowing it. At some point, the tube may close entirely; then, you will have a problem.
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Post by Sidney on Oct 21, 2018 8:34:17 GMT -8
When water turns to steam, it expands about 1000 (one thousand) times it's original volume. at 1 atmosphere water expand to nearly 1700
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Post by borderpatrol on Oct 23, 2018 2:30:02 GMT -8
Did you ever check out Ben Falk's system. It's a open loop and very safe.
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Post by coastalrocketeer on Oct 23, 2018 13:14:13 GMT -8
Another way is to do a closed loop coil in an open tank that is heated directly by the fire, thus buffering the heat applied to the closed system to 100C/212F as long as there is water in the tank.
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Post by keithturtle on Nov 6, 2018 22:36:57 GMT -8
Geoff Lawton takes the time to diagram the design in this video and explain why the water bath approach works so well www.youtube.com/watch?v=1oDpmmsqHwQNot the quickest but definitely safer than a flash boiler direct heat model Turtle
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Post by johnjorgensen on Jan 22, 2019 2:27:03 GMT -8
One thing that could create a serious problem is ice in the system. Ic can make an open system into a closed. So you might want to add anti freeze or something...
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Post by BenAlexanderT on Jan 22, 2019 4:48:31 GMT -8
Geoff Lawton takes the time to diagram the design in this video and explain why the water bath approach works so well www.youtube.com/watch?v=1oDpmmsqHwQNot the quickest but definitely safer than a flash boiler direct heat model Turtle What about the copper heat exchanger inside the stainless steel tank. If you have the faucet closed at some point the copper heat exchanger will have the same temperature as the water tank. That means, if the water tank is at boiling temperature then the heat exchanger will also be at boiling temperature. So, the water pipes can still explode, right? Correct me if I'm wrong.
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Post by peterberg on Jan 22, 2019 5:42:13 GMT -8
If you have the faucet closed at some point the copper heat exchanger will have the same temperature as the water tank. That means, if the water tank is at boiling temperature then the heat exchanger will also be at boiling temperature. So, the water pipes can still explode, right? Correct me if I'm wrong. You're wrong, the copper pipe is at the mains pressure. Which means boiling temperature in the pipe is higher as compared to atmospheric pressure. The water in the tank won't get hotter than 100º C while boiling point in the pipe is 110 or 120º C. So it'll never go boom this way. See the explanation by the inventor permaculturenews.org/2012/11/23/rocket-stove-hot-water/
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Post by BenAlexanderT on Jan 22, 2019 7:42:11 GMT -8
If you have the faucet closed at some point the copper heat exchanger will have the same temperature as the water tank. That means, if the water tank is at boiling temperature then the heat exchanger will also be at boiling temperature. So, the water pipes can still explode, right? Correct me if I'm wrong. You're wrong, the copper pipe is at the mains pressure. Which means boiling temperature in the pipe is higher as compared to atmospheric pressure. The water in the tank won't get hotter than 100º C while boiling point in the pipe is 110 or 120º C. So it'll never go boom this way. See the explanation by the inventor permaculturenews.org/2012/11/23/rocket-stove-hot-water/Ok, now I get it. I never thought of that. It's the same principle as the engines that use a vacuum to produce steam in lower temperatures to reduce energy consumption. Only though in my case it's the opposite, concerning pressure.
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Post by keithturtle on Jan 22, 2019 10:24:45 GMT -8
The freezing issue is real, if the whole unit is outside in the cold and not operating. It would take quite a while for the submerged coil to freeze solid, but the feeders could freeze if not protected.
Aside from that, it is still safer than flash-heat approach by far, IMO. Much safer.
A flash heat unit could be easier to move inside where it can be safe from freezing, and still blow up
Turtle
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serg247
Junior Member
The mountain can not be conquered, it can allow it to ascend...
Posts: 111
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Post by serg247 on Jan 24, 2019 22:22:30 GMT -8
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Post by jdawgsplace on Jan 31, 2019 8:53:30 GMT -8
could a coiled loop be encased in a dry jacket heat sink; such as sand?
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