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Post by coastalrocketeer on Feb 5, 2019 11:06:48 GMT -8
could a coiled loop be encased in a dry jacket heat sink; such as sand? It could, if heat input surfaces and collection surfaces are properly placed in relation to your solid ballast material... That would reduce the initial intensity of heat input, and could keep boiling from occurring, but total prevention of boiling/excessive heat input, would depend on having enough sand to ballast the maximum possible heat output from the burner to ensure the sand never exceeds 100C, As sand does not have the inheirent phase change based temperature limiting function of an open tank of water around your collection coil. In short, it could still blow up, given a rate of heat input from the ballast mass, that exceeds the ability of the system the coil is connected to, to move water and dump heat.
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Post by jdawgsplace on Feb 5, 2019 23:13:45 GMT -8
thx...a t&p is always a good idea/cheap insurance...a day heat seems more reliable and easier to build
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Post by coastalrocketeer on Feb 9, 2019 13:02:07 GMT -8
I think a coil in an open bath tank whose “ballast water” is the only thing directly heated by the flame, is the easiest truly safe way to heat water.
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Post by coastalrocketeer on Feb 9, 2019 14:44:30 GMT -8
It truly makes having a “closed” and even pressurized (ie; connected to your domestic hot water) collection loop safe, as long as there is plenty of water in that outer tank.
I like the idea of a float system, that mechanically actuated a damper that will block off the air through the j-tube or exiting the batch box if water is not filling the outer tank sufficiently to float it to the necessary height.
I think for safety it would best be a system that triggers the door fully closing, and requiring manual reset to restart the heater.
The other option would be to have a 3-way type of door that entirely redirects the exhaust away from the bell & tank and to the exterior, perhaps into a barrel that dumps heat then to the exterior...
I am planning on putting a mass heater “boiler” or this type in my front yard, inside an all metal shed to keep our locally copious amounts of rain off of it... and so would just send the hot exhaust out the top or side of the structure, which would be mere inches from the exit of the heater core into the bell.
Bell will be stacked cinder block with insulation outside, and an open top tank as the lid, with something like a spa cover over the open tank to keep heat in the tank for my closed loop DHW coil and an open loop pipe circulating the water in the tank to radiators and in-floor hydronic piping in the house.
Probably a DSR2 batch box.
A float based safety system like that Is something that would need development after I get the initial unit built.
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TexasGonzo
New Member
Just a typical polymath, and crazy as a can 'o chickens. 😨
Posts: 2
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Post by TexasGonzo on Mar 14, 2019 18:39:13 GMT -8
What a topic! I need to consult this [polymathic genius] buddy of mine that holds "A" certifications in both fresh and waste water treatment... I remember a system he built decades ago that was fired by a typical wood stove which he used to heat his whole house via thermosiphon *alone*. Each room had a small car radiator blown by 12v fans (off solar btw). It required a proper grade on each leg for the siphon to function properly, but he had it down! As I recall,the circulating side was a completely closed system, otherwise the siphon wouldn't do it's thang. I'm pretty sure he used an exchanger as well, as not to boil the circulating water supply.
The unfortunate part is he is now in the final stages of stage 4 lung cancer, so he might not be very open to having his brain picked at this point... but I'll give it a shot! (hasn't been very responsive even to texts lately). Too bad rockets weren't popular ~30 years ago, he would have really had an efficient setup with that at the core!
Regardless, we need to get this fingered out so I can deploy it in my Santa Fe crewcar "tiny haus" setup...
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Post by coastalrocketeer on Mar 15, 2019 0:27:04 GMT -8
In a tiny house, an emptyable 55 gallon drum or two inside the insulated structure could provide a direct radiative thermal mass that you empty when moving from place to place.
Filled wirh 50 gallons each, they would store 880 pounds of water, and I bet well heated would keep a tiny house warm for days after a charging.
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Post by coastalrocketeer on Mar 15, 2019 0:33:27 GMT -8
whoever said it earlier... that a thermosyphon system has to be closed...
I believe that is incorrect.
For a thermosyphon to work, a couple of rules I know...
The tank HAS to be higher than the heat source...
tubing diameters need to be significantly larger than in actively pumped systems due to the low motive forces involved (more so the larger the heat input in relation to water volume in the pipes.
I do believe the tank CAN be open, but ONLY as long as the top of it is higher than any other water filled part of the system connected to it.
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Post by DCish on Mar 15, 2019 5:25:00 GMT -8
whoever said it earlier... that a thermosyphon system has to be closed... I believe that is incorrect. For a thermosyphon to work, a couple of rules I know... The tank HAS to be higher than the heat source... tubing diameters need to be significantly larger than in actively pumped systems due to the low motive forces involved (more so the larger the heat input in relation to water volume in the pipes. I do believe the tank CAN be open, but ONLY as long as the top of it is higher than any other water filled part of the system connected to it. I don't know a ton about these systems other than what I've seen in my wife's country (Kazakhstan) where mud brick houses are often heated with coal. Often the most central wall in the house is a zigzag flue so the whole wall gets warm. In larger houses with more remote rooms, there is often a thermosiphon system such as you describe. One side of the coal stove is a water tank, and is the lowest point in the system. Mounted at the ceiling above the stove is a small tank that is the highest point in the system. Then 2" or so diameter pipes run to radiators in the various rooms to be heated. Each later room has a larger radiator to compensate for the fact that it is cooler than the last room. Clever system, no electricity required!!! In these systems the tank is less of a heat reservoir and more of a way to ensure that there is space for overflow, and to ensure that the system never runs dry.
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TexasGonzo
New Member
Just a typical polymath, and crazy as a can 'o chickens. 😨
Posts: 2
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Post by TexasGonzo on Mar 15, 2019 6:47:01 GMT -8
I never said for fact that the circulation side was closed... to quote myself: "As I recall,the circulating side was a completely closed system".
Again, this is aomething I haven't laid eyes on in 30 or so years, so give me some leeway here ok? Until I can make contact with my friend that built it, exact details will be difficult to remember.
Something I am sure of with a thermosiphon of any kind, hot goes up, cold goes down, that part is absolute. Also, plumbing diameters and grades along each and every part of the system need to be fairly spot on. I'm not a specialist on fluid dynamics, but my buddy is (or was, still can't get in touch with him, so it may be too late at this point).
At any rate, I mainly chimed in to give everyone just one more avenue of thought to persue... afterall, that's the greatest part of open source think tanks, right? Being new to the forums, know this about me... I will never make a disrespectful post. I'm only here to [hopefully] help further discussions, and add my 2 cents when possible, respectfully. I've been reading these forums for a few months now, and just now took the time to register. I'm also the type that doesn't just think "outside the box", I don't even recognize a box to start with. 🙃
Peace and prosperity to all... and never stop learning!!!
Gonzo
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Post by gadget on Mar 15, 2019 9:44:30 GMT -8
One thing to think about is how much water, to what temperature and how quickly you want to heat it. What I mean is from my experience heating water takes allot of heat input and you need to consider how efficient you want to go. Whats the point if you spend 8 hours heating just enough water to take a bath? here is an example for you; I heat my greenhouse with water. I have a 330 gallon heat battery in the middle of the green house, a 55 gallon insulated tank that is a central heat exchange. I also heat grow beds with 1/2 poly tubing. I heat with a rocket mass heater with 25 feet of 3/8 copper coil directly above the heat riser inside the barrel. It gets 1000F+ and above flue gas direct heating. I have a second coil in a bell thats 20 feet of 1/2" copper that gets direct 300F-400F flue gas. They are open systems on both ends and have some drain back when or if the pumps stop. (It is a test setup and not what I would consider safest yet) donkey32.proboards.com/thread/3473/mini-rocket-forced-induction?page=2Point is, I have run this thing for 10hrs with top barrel temps around 950F and can get all the water up to about 100F. So what am I trying to say? From my experience it takes a ton of heat to warm up water. Now granted there is heat loss while I am warming them up but still it takes forever. I would like to be able to get the water up to 120F in about 3 hours so I am going to resign it with much more copper surface area and insulated bells trapping heat around the coils and see what happens. Not sure if this is reasonably possible. FYI I have accidentally boiled both coils on separate occasions. Heating water is a scary proposition and it goes to show how easy it is to have a major problem. When I once forgot to turn the high temp pump on the coils boiled and pushed and popped the small amount water left on the coils back to the 55 gallon barrel kinda violently. The low temp coil pump also stopped once but showed no signs of anything other then the rubber lines where much warmer then normal. My concern is not boiling water in the tubing as much as damaging copper tubing that can get over heated. What if it collapsed and created a blockage for the next time it was used??? I would like to also mention the possibility of running water heating lines inside of other larger open-ended pipes?? That way if there was a line rupture it would be more contained and less likely to spray? How about running it inside 2" fire hose? Yes we need to prevent explosion in the exchanger but what about the transfer piping? I like the idea of it being contained.
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Post by coastalrocketeer on Mar 15, 2019 16:45:28 GMT -8
I never said for fact that the circulation side was closed... to quote myself: "As I recall,the circulating side was a completely closed system". Again, this is aomething I haven't laid eyes on in 30 or so years, so give me some leeway here ok? Sorry, gonzo... I responded to that after reading another few posts and wasn’t saying what I said to say “that is wrong” so much as to impart what little I remember of what I’ve read about thermosyphon systems, and my own logical deduction that they CAN have an open tank, but only as the highest point in the system. (Had to think about that some when considering how to get hot water to and from my (at this point theoretical) open top “radiator barrels” from my “open top” rocket heated tank, sitting at different heights, inside and outside my structure to heat.) I realized that I will have to pump cold water uphill from the radiator barrels to the heated tank and let it return through an overflow on the tank... otherwise the barrels have to be sealed for a pump at the open heated tank to push water out and have cold return uphill... My apologies for both mis-remembering and misquoting your words, AND for having left you feeling attacked in any way, as that was not my intent at all. My response was intended purely in a similar intent to yours for sharing of our own notions, reasoning, and logic behind them for the mutual educational experiences. Thanks for being so gracious in your reply.
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Post by coastalrocketeer on Mar 15, 2019 17:04:27 GMT -8
One thing to think about is how much water, to what temperature and how quickly you want to heat it. What I mean is from my experience heating water takes allot of heat input and you need to consider how efficient you want to go. Whats the point if you spend 8 hours heating just enough water to take a bath? here is an example for you; I heat my greenhouse with water. I have a 330 gallon heat battery in the middle of the green house, a 55 gallon insulated tank that is a central heat exchange. I also heat grow beds with 1/2 poly tubing. I heat with a rocket mass heater with 25 feet of 3/8 copper coil directly above the heat riser inside the barrel. It gets 1000F+ and above flue gas direct heating. I have a second coil in a bell thats 20 feet of 1/2" copper that gets direct 300F-400F flue gas. They are open systems on both ends and have some drain back when or if the pumps stop. (It is a test setup and not what I would consider safest yet) donkey32.proboards.com/thread/3473/mini-rocket-forced-induction?page=2Point is, I have run this thing for 10hrs with top barrel temps around 950F and can get all the water up to about 100F. So what am I trying to say? From my experience it takes a ton of heat to warm up water. Now granted there is heat loss while I am warming them up but still it takes forever. I would like to be able to get the water up to 120F in about 3 hours so I am going to resign it with much more copper surface area and insulated bells trapping heat around the coils and see what happens. Not sure if this is reasonably possible. Bare copper coils make good water to water heat exchangers but poor water to air heat exchangers as they lack the surface area for the air side... the ones that go in A/C systems have lots of aluminum fin area for the air side. My idea is to take the coil and solder on scraps of solid 10 and 12 gauge copper electrical wire I have laying around on... to increase the air side surface area. I will have the coils spaced and have the wire run from each one to next, wrapping once or twice around each as it goes. This sound give better conduction on the air side I’m betting you are making PLENTY of BTU’s to get your desired temperature rise in that tank, but you’re only collecting 5-10% Pressure release valves on BOTH ends of each “hot zone” collector, with piping to carry any steam off in a safe direction would be prudent for anyone experimenting thus.
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Post by gadget on Mar 16, 2019 6:48:13 GMT -8
Bare copper coils make good water to water heat exchangers but poor water to air heat exchangers as they lack the surface area for the air side... the ones that go in A/C systems have lots of aluminum fin area for the air side. My idea is to take the coil and solder on scraps of solid 10 and 12 gauge copper electrical wire I have laying around on... to increase the air side surface area. I will have the coils spaced and have the wire run from each one to next, wrapping once or twice around each as it goes. This sound give better conduction on the air side I’m betting you are making PLENTY of BTU’s to get your desired temperature rise in that tank, but you’re only collecting 5-10% How about soldering the copper tubing to an aluminum plate? I am going to measure the flow rate and temp rise and see how much heat I am collecting next chance I get. Soldering wire is not a bad idea either. Another Idea I had was to just use an automotive radiator. I could take the plastic tanks off and weld some aluminum on. I'm not sure how well aluminum holds up in the flue gases. That info is hard to find.
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Post by coastalrocketeer on Mar 16, 2019 9:12:06 GMT -8
the plate idea is likely workable, though I know nothing of the methods by which one could potentially solder aluminum to copper.
That plate as the top of a bell could be quite good I would imagine, and very easy to clean, compared to other things.
My idea for mine was to make it like the condenser coils under or behind a refrigerator. They are designed not to get clogged by particles too easily, and be easy to clean. The wire will provide good surface area enhancement and I have many 5-25’ sections of 3 conductor as scrap from remodeling, just have to strip and solder.
One should assume anything with small openings like a car radiator will need cleaning much more often than a more open design or a plate design as you suggested.
The only things I would worry about with the aluminum plate, though I don’t know enough to predict whether they would actually be an issue are:
•Potential melt down if in too hot an area of the stove (aluminum doesn’t glow like steel before turning to liquid) probably only a concern directly over the riser, and if the water is not able to sink heat away fast enough.
•Increased corrosion effects of dissimilar metals exposed to combustion byproducts combined with condensed water.
•Achieving good thermal bonding of aluminum to copper.
I don't see any potential issues beyond those, but others may, I also have no idea whether any of those three would be a problem in practice.
Would definitely enjoy learning from any experiment with aluminum plate bonded to copper pipe that you do...
I am presently mulling over how to weave copper wire between fixed sections of 1/2” copper pipe such that I will not be having to “pull it all through” each time around, ot “push the whole roll around” each time.
I am thinking I may go with taking straightened lengths of wire and pressing a “U” in where it will contact each pipe, then I can alternate them on both sides of the rows of pipe without having to do any “weaving”
It should be easily cleanable with a brush that way.
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Post by gadget on Mar 19, 2019 8:27:28 GMT -8
the plate idea is likely workable, though I know nothing of the methods by which one could potentially solder aluminum to copper. That plate as the top of a bell could be quite good I would imagine, and very easy to clean, compared to other things. My idea for mine was to make it like the condenser coils under or behind a refrigerator. They are designed not to get clogged by particles too easily, and be easy to clean. The wire will provide good surface area enhancement and I have many 5-25’ sections of 3 conductor as scrap from remodeling, just have to strip and solder. One should assume anything with small openings like a car radiator will need cleaning much more often than a more open design or a plate design as you suggested. The only things I would worry about with the aluminum plate, though I don’t know enough to predict whether they would actually be an issue are: •Potential melt down if in too hot an area of the stove (aluminum doesn’t glow like steel before turning to liquid) probably only a concern directly over the riser, and if the water is not able to sink heat away fast enough. •Increased corrosion effects of dissimilar metals exposed to combustion byproducts combined with condensed water. •Achieving good thermal bonding of aluminum to copper. I don't see any potential issues beyond those, but others may, I also have no idea whether any of those three would be a problem in practice. Would definitely enjoy learning from any experiment with aluminum plate bonded to copper pipe that you do... I am presently mulling over how to weave copper wire between fixed sections of 1/2” copper pipe such that I will not be having to “pull it all through” each time around, ot “push the whole roll around” each time. I am thinking I may go with taking straightened lengths of wire and pressing a “U” in where it will contact each pipe, then I can alternate them on both sides of the rows of pipe without having to do any “weaving” It should be easily cleanable with a brush that way. Ok, how about doing a circle coil but start at the middle and work your way out from the center weaving as you go? Should be easy to make it that way. Maybe that underwater basket weaving course in college will finally pay off. How about this, Start with an insulated barrel setup as a bell for trapping heat. It would have a removable lid/clamp setup. Have a coil of copper attached to the lid just below the insulation. Use fitting to allow a flare connection to the coil. Pressure/temp relief valves above the fittings out side the lid. Then rubber steam hoses to the transfer pipes. The rubber steam hoses allow the lid to be opened up for cleaning the coils.
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