Now that you were given confidence (I hope) in the last chapter to build your own solar-heater tank, the storage tank is a piece of cake. No plexiglas top needed. No seals needed at the corners if liners are used, and it sits out of the sun. It could have the life-expectancy of a sea tortoise, even if it's made of wood. The tank must only hold the water's weight, because the liner will hold the water. Yes, liners are available that hold hot waters. Just put on your miracle-working power, and give the command, "Liner, drop thyself into that there box crate," and it shall be done for you, just as soon as you drop it in with your own two hands.
If liners cost too much, the purchase of liner membrane alone, not to any particular shape, should be less money. Just drop the membrane like a tarp into your wood crate, and cut the excess along the top of the crate. Or don't cut it, because, if a tank of a different shape / size is decided upon later, the membrane might still be usable for it. Just google "tank liners" or "pool liners" or "pond liners." Some selling these things may also sell high-temperature liners.
In the world of the wicked, liners aren't cheap. It used to be that mass-produced products were priced according to manufacture cost, but in the world of the wicked, things are priced according to what sufficient people are willing to pay for it when given no choice by the price fixers. When manufacturers and distributors invented "suggested retail price," it was a price-fixing scheme allowing them larger selling prices. The object of the wicked today is to buy up all the distribution channels of a certain product, while controlling the retailing end too. Price-fixing is easy when there are only two or three big ones at the top from which most of us purchase. If a tank liner can make it possible to build your own tank, the people who sell liners raise the price according to your savings on a tank purchase regardless of how cheap it is to manufacture a liner. They make you the loser one way or another. But you have options. You don't have to buy their liner. Not everything needs to be so quick and easy at your added cost in money.
There are thin and cheap plastic sheets sold everywhere to face tub and shower surrounds. It's cheap because it makes for the most-basic look in a shower, and so prices are accordingly. But what about using foam insulation in the tank, as we're making an insulated tank to begin with? The foam is water proof, and made to withstand the hot summer sun beating down on a house wall with that insulation trapped inside the wall.
Build four stud walls to form your square/rectangular crate. Cover the inside with 3/4" plywood. Glue in the plastic sheets, or set in the foam insulation tight (keeping expansion distances in mind), and have the inside corners siliconed generously with the best silicone suitable for hot submersible conditions. If it eventually leaks in the basement near a drain, it may be no problem; just empty the tank and re-silicone. We'll teach those liner people a lesson.
You may agree that a wood tank in an attic of a house should have a one-piece liner if possible, unless you don't value the ceiling much below the tank. You could insist on angle-iron on all outside corners, though one layer of plywood isn't enough for decent screws in the angle-iron. Two layers of plywood would do it.
It would make for a good design feature to screw into the studs through the plywood -- from the inside of the tank -- but only if using a one-piece liner. Otherwise, without the liner, there needs to be a way (brackets. for example) from the outside to fix the plywood in contact with the studs; it's especially important that the corners do not move after siliconing, when the tank is filled with water. All corners need to be tightly against the studs at the time of siliconing.
Insulating with pink between studs is easy enough, but then cover the studs with vapor barrier and thin plywood. Apply a well-insulated lid of some sort with some clamping mechanisms all around for a steam-proof seal. The lid can be a piece of plywood covered in foam insulation on the inside and out, but with a sheet of poly plastic wrapped around the plywood before the foam goes on. Your lid is now water proof. If the lid plywood is inches larger in dimensions than the tank, there will be plenty of places for the type of clamping mechanisms used on tool boxes. There is gasket strip of multiple types and sizes at your local building center.
Aside from the piping, you're done. I know it's too hard to believe. In the world of globalist forces, it should soon be against the law to make your own hot-water tank this cheaply. Don't kid yourself; globalist forces are scheming right now to capitalize on the green-energy market that's being rammed down everyone's throat.
There needs to be an air hole to allow water in and out of the tank, and so make it the steam hole too. In other words, make the air hole a small tube from the tank lid to the outdoors. The smaller the hole, the less water and heat is wasted out of it, but I wouldn't go less than 1/2" anywhere in the line, including the inside diameter of the nipple through the lid. If the tube is long and gradually rising on a better than horizontal slope, much of the steam can condense on the tube walls and fall back into the tank as warm water. Whenever a globalist drives by your house with his bullet-proof Continental and sees that little 1/2" pipe sticking out, you'll get him good and mad.
The beauty of a circular tank is that a single sheet of waterproof material creates a single wall (i.e. instead of four) of the tank with just one (instead of four) vertical seam. The seam is just the end of one sheet as it presses against its other end. The two ends need to be clipped tight to one another. I would call for insurance here by bolting the ends together along two vertical lines (from tank bottom to tank top) about six inches apart. But bolt through 4' long metal strips (four in all) thick enough to maintain a good seal, with bolts spaced closely. Sandwiched between the two ends of the sheet, there should be some glued-on rubber; the four metal strips press the sheet tightly against the rubber. I'm thinking that this will make a good seal, but it's your decision. For good measure, silicone the seam.
Some hot-water tanks are recommended for replacing every ten years due to rusting out (I don't know whether they come galvanized), though they last longer before leaking. Hot water tanks are usually replaced, not when they leak, but after too much rust makes the water murky. It's a manufacturer's beloved defect, shortening the time that their tanks can be used. But with our home-made unsealed tank, we can get inside after many years to remove rust settled on the floor. We could eventually add a new sheet of metal inside, fixed with the seal above. We need to have a green plastic flag on our 1/2" pipe to indicate to all globalists that we have the eternal tank design, making them see red when looking at green.
Perhaps the tank above can have the metal sheet alternated with a 1/8" (or slightly thicker) sheet of plastic. Instead of making the tank four feet high, we can easily cut the plastic in half (with a typical utility knife) to make two tanks two feet high, if the weight of water is a concern. There is a soft PVC sheet (I've worked with it) that should form a round shape quite easily after being left in the sun. Your local sign company has samples of plastic types, and may sell full plastic sheets, or can direct you to his supplier.
One 4' x 8' sheet of 1/16" thick steel is priced (January 2013) at $65 in Kentucky. The same thickness with temporary rust-proof galvanized coating is listed at $107 (galvanized steel is acceptable in cold potable water, but the zinc coating may scale off inside a hot water tank after some years). Metal in 1/16" (= .063") thickness and in a cylindrical shape will hold water at a four-foot depth, but it may be too thick to make round at home.
The webpage above shows a 4' x 10' sheet of thinner metal ($75), with a thickness of .048", which can make a tank 38" in diameter...with over 200 gallons when filled near the top. We could climb in and have a sauna bath, dunk our heads and blow bubbles in celebration. An eight-foot long sheet makes a tank 30 inches in diameter...about 150 gallons. The 4' x 8' tank as described in the last chapter was little more than half that volume.
If you think the .048" metal is still too thick to form round at home, one sheet (available in 4' x 10') of the .036" steel ($66 per piece), and one galvanized sheet ($86) of .034" thick, should be combined do the trick (each sheet could be rounded separately).
It's not the width / broadness of a tank that causes water pressure, but the height. A tank a mile long at 4' deep would have the same requirement for a seal as a tank 30" wide at 4' deep. Freshly poured concrete (on the dry side, and tamped down hard) at least 1 1/2" deep on the inside of the tank body would go far to giving it a good seal at the floor. However, when the water fills the tank, the weight of water acting equally in all directions will tend to make the tank perfectly round although it may not have been prior to filling. The effect might be to change the shape around the concrete, causing a significant leak. The avoid this, pour concrete all around the outside of the tank too. There will be a wood frame around the tank for the concrete to sit in while wet, if you add a 2 x 4 housing around the tank.
Consider the limitations of a bottomless tank merely set in thin concrete. If kids are playing in the basement, and one of them falls against the steel body, it could move sufficiently (not likely, but it could) to break the seal at the floor. It's therefore a safeguard to build a square 2 x 4 housing around the tank, and to cover it with panels. Where the four bottom 2 x 4 plates cross nearest the tank, let there be a few inches (between the frame and the tank) of space for the concrete. At these four locations, drill one hole through each of the 2 x 4 plates, and further into the floor for insertion of screws. I would suggest poured concrete 4" deep at the tank walls, tapering off to no less than 1" deep at the bottom 2 x 4 plates.
Another safeguard to the movement of the tank after the concrete is poured is a few screws through the sheet (from the inside) prior to pouring concrete that will be buried in the concrete. Some rubber washers on those screws seems a good idea.
In re-consideration, I wouldn't pour a concrete slab inside the tank, as it will want to expand when heated by the water, but with no room to expand. It may not damage the tank, but it may tend to ruin the seal at the floor. What seal?
I doubt that the concrete alone, even if it's 4" deep in and out of the tank, will keep water / humidity from getting out. Concrete just doesn't stick to metal, and moreover it's not flexible. Adding some latex additives to the concrete will give it some flexibility, but it may not be enough. Here's what I suggest. Before pouring concrete, lay a mat of rubber on the floor, keeping in mind that the water in the tank will not transfer much at all to the metal sheet. The metal sheet will only sit on the rubber with it's own light weight in combination with the weight of the tank lid. The heavier the lid -- or the weight upon the lid that you provide -- the more the sheet will press down into the rubber for a good seal.
Plus, the weight of water will press down on the entire rubber uniformly, tending to squeeze the rubber into the metal sheet, wherefore a highly elastic rubber may be best for this purpose. While this would amount to a significant seal if the floor is perfectly level, the floor may not be. It's up to you to fiddle with whatever is necessary to get a good seal using this method.
Then, before pouring the concrete around the outside of the tank, apply the right type caulking (all around the bottom of the steel body) that adheres well both to your sheet and to the rubber. The black roof caulk (tar looks to be one of it's main ingredients) may work well here. Some silicones may be appropriate but make sure. Use silicone that can be in constant contact with water. I suggest avoiding silicone-latex combinations. After the caulk hardens and cures somewhat, you might add some tar material over it, as used in concrete foundations. Or perhaps add roof caulk over the silicone. Finally, pour the concrete and tamp it down to make the best seal possible. But this may not be enough as the water is predicted over time to loosen the caulk and get through.
A silicone / rubber caulking all around the inside the tank is a promising step, for the weight of water will tend to hold the caulking in the inside corner even if water loosens its adhesive grip. Whatever you use on the inside, keep in mind that it can loosen and become part of the water. Therefore, a ring of concrete (not a slab filling the entire bottom) over the caulking will allow the water pressure to act down harder on the seal, and meanwhile keep the silicone in place where its best kept. I doubt that silicone would stick to the concrete for long while the concrete is perpetually humid, wherefore don't use silicone on the concrete.
The outer concrete is only to keep the shape of the tank when water fills the tank. You could avoid concrete if you have the ability to make a metal cap for the bottom.
We now need an automatic shut-off valve. This is where we can put the screws to globalists unless they opt to buy up all the toilet companies too. Fortunately, people are not making their own unsealed tanks to the degree that automatic shut-off valves are selling for $500 per ounce. So far, we're lucky, because it's an amazing instrument in what it accomplishes, doing untold work for us virtually free, saving us countless times from running up and down stairs, or in and out of the attic, to shut off water. One can get an automatic shut-off valve, the ones for toilet tanks, at Home Depot for under $20. And they work every time without fail for at least ten years easily. Get an extra one or two for the trib.
You need to arrange a pedestal or ledge inside the tank with a hole drilled into it to receive the bottom of the shut-off valve. I believe the valve purchase comes with it's own washers and nut. Screw it on, and arrange the pedestal/ledge at just the height you want it, and the tank is ready for service. Whoo-hoo, as the ladies say, because they were getting tired of the technicalities for building the tank.
We're not finished here, ladies. Don't get excited yet. I know how easy and carefree it is to just throw on any old lid for the tank, and be done with it. But if you don't want pieces of flies in your hair through the shower head, arrange to keep them out of the tank. A lid with just a little crack may allow more than flies in, and likely their eyeballs will get through. You don't want that kind of silky-smooth hair, ladies. The good news is, drowned flies may float and not get to the exit hole of a storage tank; the bad news is, spiders can sink to the bottom and be amongst the first out of the tank.
So, when you see your husband locating the shower-destination pipe out of the tank floor, tell him, honey, you should maybe make that pipe come out a couple of inches high from the tank side instead of from the very bottom. When he asks you what for, and you're too ashamed to be a wimp concerning spider guts in your hair, just tell him that rust from the metal tank will accumulate on the tank floor. He'll only have one thing to say, "you're right again, honey."
Don't imagine all is wonderful in that tank when in reality it may have mold / grime no matter how well the lid's tight. The water temperature will not always be hot enough to kill such things. Give the tank some bleach once in a while.
The Basement Tank You Might Better Not Have
If we are using an automatic shut-off valve situated at the storage tank's water level, it will tend to feed the roof-tank water to the top of the storage tank...because this feed must go to the shut-off valve. Therefore, either cooled or heated waters will be fed to the top of the storage tank whenever anyone turns on a hot tap. If your family takes showers early in the morning when the roof-tank waters are colder than the storage tank waters, the first person in the shower triggers the entry of cold roof waters into the storage tank. That's because the turning on of hot-water taps triggers a pump removing water from the storage tank, with the resulting decease in tank water level opening the automatic shut-off valve.
What a lousy thing. The colder water entering the storage tank sinks, cooling all the water in between. It pretty much doesn't matter where in this tank the water is taken by the pump, it will fail in taking the warmest waters possible at all times. A basement storage tank is best when family showers are taken in the evening. In such a case, the pump should take water from the near-top of the tank.
None of this is to say that you'll be having cooler showers just because cooler waters enter the storage tank. The shower won't be taking water direct from the storage tank while we're still operating normally in this world. Instead, the tank water goes first to the regular water heater, where gas / electricity heats it before coming to the shower. The money-saving trick, however, is to direct the warmest-possible waters into the regular water heater, thus delivering a one-two punch right into the face of the oil companies. Grrrreat!
It's only later, in the trib, that we'll want water directly from storage tanks, and by now you can see that a storage tank in the basement is only of mediocre performance.
The only way I can think of for having normal shower / tap pressures in the house while incorporating unsealed solar tanks is: to use a pump and pressure-tank combination between the storage tank and the regular hot-water heater. Don't get dismayed here, because the pump (doesn't need to lift water) with pressure tank will cost peanuts compared to what they will save you in gas / electricity and related taxes. The pump should perhaps be made for hot water, but for all I know at this time, a cold water pump may do. Let's hope, because the Little Giant webpage below features a 1/3 HP hot-water pump for $337 (January 2013). Inquire on warm-water pumps, or the temperature ratings of cold-water pumps.
Down the page below are some hot-water circulating pumps that can handle faster loads, but at the top of the page there are DC pumps capable of handling hot water that seem excellent for trib purposes. It can be important that the flow rate of the pump removing storage tank waters is on the slow side, as are these small DC pumps:
Here is a pump boosting water pressure needing no tank, but, of course, the price jumps way high ($672) because you save on the tank, meaning the manufacturer decided he should get your savings. It's the new way of mass production, appropriate for Armageddon's fires. There's not many people doing us any favors in the market place in return for our business. If they offer "good" prices, it's only because they offer cheap products fully aware. Tank Depot seems to be highly priced all around. Shop elsewhere.
The pressure tank should be insulated itself, as it acts as a storage tank too. It would be a good idea if the pressure tank were inside the warm housing of the larger storage tank. It begs the question of why we shouldn't have a small pressure tank (5 - 10 gallons) sitting on the storage-tank lid since the lid needs weight, and since it's warm up there.
There is a negative in all this. Your household may have municipal water pressures that are higher than typical water pressures provided by pump and pressure-tank combinations. Plus, the smaller the pressure tank, the more often it will trigger the pump to work so that your shower will be a see-saw of high and low pressure. If you're not willing to have this minor negative, then you can't save on solar as prescribed here. I was raised exclusively on municipal water, and not until my 4th decade did I live in a house with well-pump pressures see-sawing between 40 and 30 psi (my pressure choices). It was fine. You can raise the pressure to 50-40 psi if you wish, and you probably won't have a complaint if you've been accustomed to municipal water.
If you need to draw this all on paper, it's understandable. One side of the pipe from the pressure tank will feed your regular hot-water heater, wherefore you are going to shut the in-house water valve on the in-house cold pipe that now directs very cold municipal / well waters into your hot-water tank. In the meantime, forget that cold pipe until the winter. You have a new way for the time being. You are going to bring much warmer waters into your hot-water heater.
The long-term odds are that the tank water taken by the pump from a basement storage tank will have an average temperature midway between the average storage-tank temperatures and average roof-tank temperatures. It's not very good. As much as you'd rather have the tank in the basement than in the attic, you need to do what you need to do, man. That's why men have short hair, because it's their job to get into spider-filled spots. Living spiders, that is, ones with tiny little brains that seem to act a lot faster than ours. A spider has one eye per very fast leg. The only consolation is that we and they are deathly frightened of one another. I ask you, who's smarter? When an attic spider sees us, it runs away on a roof rafter. When we see a spider in the attic, we jolt our head back hard into a roof rafter. That spider then stops and thinks to itself, "what a dummy."
I know what it's like to be a city person with spider phobia, but living in the Texas country made me a man. You just wouldn't believe the insects at that place. Pulling ticks out of my skin was a near-daily routine in the first year. Scorpions in the house at times, yep.
Do not go into your attic if it's filled with bat or mouse droppings. First, go online to learn about the dangers to your health, and deal with it first. See histoplasmosis.
Assuming you're not the type to get into the attic, and where showers in your household are taken in the afternoon / evening, have a three-way valve in the roof-tank pipe before it enters a lower storage tank. With one turn, the three-way can shut water to the storage tank while diverting it to the pump. In this way, the pump can take water direct from the roof tanks when roof water is hotter. If visiting the three-way valve is too inconvenient time and time again, what's needed, ideally, is a computerized system working in conjunction with temperature sensors and water valves that always direct waters to the pump in accordance with the best possible scenario.
The next best thing is an electrically-tripped water valve operated from an electrical switch on the main floor or in the shower room if possible. If it's been a sunny day, and it's known that the storage tank has fully cooled water over a day or two of steady clouds, one could take waters direct from roof tanks without going to the storage tank to turn the manual three-way valve.
The webpage below offers electric water valves, though I don't know how they are tripped. It gives you an example of what's possible. If they don't have electric three-way valves, one could use two regular valves, one to shut the roof-tank line to the storage tank, and the other to open that same line to the pump. The 2400 Series by Irritrol has a price tag of under $27. Here's the 205T listed at under $20.
However, on a spec sheet for the 205 series: "Valve shall have a working pressure range from 10 psi (0,7 Bars) minimum to 150 psi." In an unsealed tank system, 10 psi requires about 23 feet of water height from top of an attic storage tank to the valve. It's not likely that you can use Irritrol valves, therefore, unless you have a two-story house with a valve in the basement (water pressure increases .43 pounds per square inch for every foot of height). No water temperature ratings are discussed in the spec sheet.
Storage Tanks for the Brave
It's a miracle you actually got into the attic with more than just your head. I saw you looking scared, don't deny it. You need to get bright light or two, and get comfortable with the surroundings. You don't really see the ghosts of the carpenters who put up those rafters? Bring up your praise music if you need to chase the goblins away. But man you've got to do this.
You'll need strips of plywood to make a platform on which to work. I know exactly what your first thought will be, human: you don't want to build a tank up there. You'd rather have a pre-made steel / galvanized / fiberglass / acrylic tub, or a galvanized barrel, or something like that...but you know none will probably won't fit through the attic entry hole. You'll either need to make a larger hole, a new hole, or build the tank in the attic. If your wife and kids lets you make a mess in one of the bedrooms for a new hole, here's some galvanized tubs that can be used for the attic storage tank(s):
I'll bet that your attic hole will allow passage of two pieces of steel, each 24" wide, cut from a 4' x 8' sheet. You could make two cylindrical tanks each holding 40 gallons (about 330 pounds) from that one sheet. You could drill the sheets and metal strips outside of the attic, and get everything in order before bolting it all together in the attic. As the tanks are so short and out of reach of children, you could probably forego the wood housing. Just pile insulation over it. Your attic hole will permit pails of concrete mixed outside.
Just locate the tanks directly above a wall if you don't think it's a good idea to have them transferring weight to ceiling joists alone. The platform under the two tanks can have a top made of a 4' x 8' sheet of plywood cut in half like the sheets.
Link the two tanks with 1" pipes at their lower ends, not up high. You need to know that some toilet shut-off valves become defective after some time in that they won't give much of a flow rate (I'm assuming that's why some toilet tanks take forever to fill). That's why you should get the best one available, usually indicated by the price tag. What you don't want is the attic tank(s) running dry waiting for the shut-off valve to replenish its supply. It would burn out your pump at worst.
It's much a waste of solar energy if our roof tanks do not allow heated waters to rise naturally through a fat pipe into a storage tank in the attic. The basement tank just won't do. With an attic tank, an entirely new piping system is needed; it's going to solve the problems that were evident in the basement tank. Things always get better when they're done right. An inventor only gets it right on the last try because he doesn't try after that. He can't get righter than right. If it's right, he's arrived. If heat goes up, it's right to have the storage tank up. End of problem. There is no end to jumping for joy in this story. Just don't hit a rafter.
Find the spot where the tank will sit after the necessary considerations. One consideration is locating it as close as possible to a sun-bathed roof surface to minimize its heat loss. Warm attic materials stay warm well after sunset. Keep in mind that you can have the heater tanks on or just off the ground.
Should you locate the attic tank over the shower / tub walls? Not if you think this may be the house for your trib retreat, because a water mixer tank would go better directly over the shower. The attic tank could best be located closest to a pipe going down to the basement hot-water tank. If that's a difficulty that depresses you because it requires knocking holes in walls, and repairing them too, bring the pipe to the outdoors at the roof area, then down into the basement with a hole through the foundation.
I keep making things harder for you, and then tell you that this is cause for joy. But a little work now is greater happiness later. Really. And it's a great selling feature if you decide to move; just show them your summer gas bills to prove how much money it saves. It's one step at a time here. Make a stool with a pile of books if your chair won't fit through the attic hole. Scribble on some paper everything you'll need in the way of materials, and get past this first stage. Once you are, you're committed. No turning back. More than half the pain might be convincing yourself to go ahead.
Take more leak precaution when building an attic tank. The hot water bursting out of a tank failure on someone below the ceiling could injure someone badly. The tank could be on a home-made pan (all around the tank) to take care of any slow leak that might be discovered before becoming too large. A small drain pipe from the pan to a place we cross paths with regularly would alert of a leak too large to evaporate from the pan.
With the attic tank sitting above the level of the roof tanks, the storage tank always gets fed the hottest waters whether the taps are open or not. The attic tank is warmer than the roof tanks for most of every 24-hour period. If someone needs to speed the rate at which roof tanks issue heat to the attic tank, increase the pipe diameter or number of pipes between the two. That is, when building your roof tank, consider whether you have sufficient passage for heat to the attic tank. It's better to have more passage at that time than not enough.
In both cases, basement tank or storage tank, the cold water feeding the solar system must initially enter a solid container with minimum size of about a five-gallon pail. Actually, the larger this container, the better, because it needs to be at the same height level as the attic tank. That is, the container can be in the attic too. O happy day. The attic temperature will be warmer much more often, between end of winter and start of winter, than the cold water entering the tank, meaning that the attic air will start to heat the cold water in the container, even before it enters the roof tank. We basically have a natural heater in the container itself that pre-heats water a little.
Scenario: you all take showers in the evening, and this "container," being, say, 40 gallons large, gets filled with cold water in an attic on a July-15 evening that's like the Sahara desert at noon. This container should therefore NOT be insulated, and would be best made of thin metal. Yes, it's going to pour condensation off it's sides, but a water pan under the tank takes care of it. A pan can be as simple as a square/rectangular frame of 2 x 2s on the ceiling joists covered with plastic poly to catch water. The longer that plastic lasts, the better.
The object of the container is to have an automatic shut-off valve at a high water level of your choice (definitely not near the very top). This container is connected indirectly by pipes to the attic tank, forbidding the latter to fill higher than the level dictated by the automatic shut-off. It's a $20 miracle that takes care of water levels in both tanks.
The lower end of the container has a one-inch pipe to the lower end of the roof tank. It's through the roof tank(s) that the container is connected to the attic tank. So, when the water from the container has filled the roof tanks for the first time, it also fills the attic tank automatically. It's a miracle, I tell you, day after day. You don't even have to be watching.
Danger: if your particular pump removes water much faster than your particular valve in the container can replenish it, the water in the storage tank may run dry for long enough to harm your pump. To minimize this possibility, use a small or low-output pump and/or have a small pressure tank (five gallons?) that quickly lowers the pump output rate. Or better yet, get a valve for the container that reliably (even years later) allows nearly as much water through as your pump takes at its maximum ability.
Lest you think toilet shut-off valves are unreliable because toilet tanks often leak, it should be said that toilet-tank leaks are not due to faulty valves, but to a wrong setting on the float that shuts off the valve. But in your container, you won't have that problem if you have the float set to shut water a few to several inches below the overflow hole. And you should have an overflow hole if only for peace of mind. The hole leads into a drain pipe, of course, and that pipe should go somewhere into the yard where you can see it.
When the roof and storage tank waters expand due to heat by day, the water level in the container and in the storage tank will go up. The expansion over 70 degrees F from 70 to 140 will be in the ballpark of two percent of the whole water body. If the roof tank has 80 gallons while the attic tank has 40, one could expect about 2.4 gallons of expansion, not very significant (about 1" deeper) if the container and attic tank have water surfaces totalling eight square feet.
Scenario: The container and all tanks are filled. Jerry turns on the shower, and water begins pumping direct from the attic tank into the small 20-gallon pressure tank, and from there it's into the household hot-water tank. Almost immediately, as water is removed from the attic tank, water level in the container drops to open the automatic shut-off. I mean, it's a double miracle because it opens by itself too. So, as water is taken from the attic tank, container water is forced by gravity to the lower parts of the roof tank, yet it's the highest, hottest roof-tank waters that are thereby forced up into the attic tank until Jerry is done. Yes, you heard right, cold water goes into the roof tank, but the hottest waters in the roof tank go into your regular hot-water heater.
There is a problem here after all. It's a big one: Jerry did a violation of common sense. He mixed cold water with the hot at the shower, wasting all that gas / electricity it took to heat up the water in the first place. Why do we do that? Why do we heat the water only to cool it down? How much money is wasted? You're a violator, pure and simple. And we've all done it.
But the solar heater can redeem us. I ask you, what is better at family shower time, to use up 80 gallons by taking it at just the right shower temperature straight from the solar-heater system, or passing 40 gallons of the same water (say at 100 F) through the household water heater (turning its heater on in the meantime), and using 40 more gallons of cold water to cool it down? It cost you plain-nuthin in gas or electricity to take the 80 gallons direct, and so you can't get righter than right. You've arrived. But by passing it into the household heater, it's got to heat 40 gallons from 100 F to about 130 F (or more, depending on your heater setting).
How can you get water direct from the roof tank at just the right temperature for your shower? Click back two chapters from here and see the cockpit invention. It'll make you cockadoodle-doo, if you're game on doing the work.
Why can't we just turn down the thermostat of our household water heaters to 100 F? There wouldn't be enough hot water for one shower, because cold water enters the tank simultaneous with water exiting at the shower head. That's why we're all forced to be in violation of common sense. The only solution is to have an abundance of water at 100 F without cold water entering that source. Although it's not easy to arrange perfect shower temperatures from the solar water alone, the ample supply of warmed waters allows you to at least turn down your hot-water thermostat to little hotter than your desired shower temperatures.
At some point in every 24-hour period, roof waters will be at a good warm temperature for laundry, no in-house cold water needed for mixing with hot.
From the Tank Depot, the webpage below features a 40-gallon plastic water tank ($72) in an 18" diameter (43" high). Just saw off the top to add the shut-off valve, and put the top back on somehow (I doubt that they can be used for hot water). However, as the secondary purpose of the container is to pre-heat service waters in the attic air, broad tanks (i.e. with large water-surface area), rather than the vertical ones at the webpage below, make more sense. As metal absorbs heat better than plastic, a deep (say 30" or more) but broad metal tub seems excellent for the purpose. See the rainwater harvesting link on this page if interested. There is also a link to a page on water-pressure booster systems (expensive, shop elsewhere).
Here's an online thing: "Davis Alternative Technology Associates suggests about 2.5 gallons of water per square foot of [tank] glazing as the maximum ratio for good heating." That sounds about three to four inches deep of water in your heater tank. If it's deeper, it won't get it as hot as quickly, but maybe that's okay because you'll get more warmed water. If I'm not mistaken, the object for the Davis people making the statement above is scalding water that they're going to mix with cold water. But if you're happy with 100 F where they're shooting for 140 F, you can make your roof tanks deeper. In the last chapter, I used 3.5" deep based on the statement above. Perhaps I was wrong to use that statement as a guide.
Anyway, if one keeps to 3.5" deep, they can have fast warm water at midday, and more warm water in the evening. In the trib, you can flush the 3.5" tank to the lower storage / mixer tanks at midday, and start collecting more warmed water for the evening. Consider it a blessing if at the end of the day, cold water needs to be added to the solar water.
The mixing tank hasn't been part of the discussion because it's for trib purposes mainly, and needs another shower head in the shower, and the required piping and valves. It allows one to take solar waters alone without passing them into the hot-water heater. However, it's a manual system making every shower a hassle, as compared to modern standards, for getting just the right temperature. It's intended for trib purposes.
Roof Tanks Can be Grounded for Assuring Better Behavior
Let's design a passive solar system where it can be used with or without electricity. It's as easy as having a tank on ground level, where you can fill it with the bucket-and-funnel method. Huh? What's a funnel? It's what every old-fashioned household had lots of. Our generation started putting them into junk drawers, and eventually we never saw them again. Old-fashioned people never had junk drawers...because they didn't have junk. Everything they had was of double usage one way or another.
Without a water pump, you already have your first problem defined, which is why even a small solar-electric system is invaluable. I understand how you feel about funnels and buckets. All the patience expended standing there, holding the pail, waiting for it to get done. It's dreadful. There's a fast-lane solution called a manual water pump. Or, if that's not good enough for you, prepare early for what's to come to avoid these old methods. Echo: even a small solar-electric system is invaluable. You can even have toast after the shower.
But don't put away those old-fashioned items. It's still legal for people to carry water into a house by pail. Wouldn't it be a hoot to see a modern woman carrying a bucket of water on her head? Instead of beads around her wrists, funnels dangle. Bucketting water from a roof tank? Yes, it's as easy as a pipe coming down to a spout near ground level. Yet, there's no law that says heater tanks need be on the roof.
Heater tanks on/off the ground have some advantages. Suppose some hot rocks could jump into the tank? Then, imagine them jumping out and bathing in the sun some more, to repeat the process every hour. Metal heats up much faster than rocks, and looses more heat in water. Imagine some hot pieces of metal sitting in the sun baking, too hot to the touch. Suppose someone arranged pieces spread out on a flat surface (this is where the cookie expertise of women comes in), then slid them into a basket of some sort made of metal wire (akin to piling dinner rolls in a basket). Then, dip the basket into the water (deep frying French fries comes to mind). The basket itself has been baking in the sun (where oven mitts). Your water just got significantly hotter in a few seconds (faster than baking cookies). There's no law saying you can't have more than one basket full of metal pieces (although Obama's wife wants to limit how many French fries we can have at one sitting). You can even dip the baskets seven times daily and not be arrested. It sounds crazy, but it works: tax-free hot water easier than baking cookies. Can't you just hear the sizzle?
How about small lengths of copper pipe, like hot dogs neatly lying side-by-side on a flat hot grill in the sun. Get some gloves on, grab as many as you can, dip for a few seconds, and lay them back out again. There is no such thing as re-usable hot dogs, but here you have a true miracle. The only difference between the miracle of hot rocks jumping into your hot water and you placing copper pipes into it is the miracle of your movement. Pick up the next pile, and do it again, looking over your shoulder to check for revenue people. They know how to tax you for using the sun, so be careful not to tip them off, or short pieces of copper pipe will have tax built in to them.
Now that one is planning to add extra heat to the water tank, it can be made deeper than roof tanks. With deeper tanks, two black collector surfaces can be exploited, one on the tank bottom, and the other on the back side. Don't throw those old mirrors out; they are solar reflectors above the tank. What I have in mind for a deep tank is an aquarium style, with three sides and the lid all in thick plexiglas but sealed at the joints with rubber rather than silicone.
Where's a good place to heat water on the ground? Right up against a south wall, not necessarily of the house, where heat accumulates in all the surrounding materials. A tank lying on the ground won't benefit from a relatively cool ground temperature. At cool times of the year, it would be better to elevate the tank off the ground while allowing sun to shine underneath it on yet another metal surface acting as a "heating element." Enclose the space over that metal with a transparent material, and much of the accumulated heat within will get into the tank.
The cool seasons are when people have extra energy for dunking hot metal into a deep tank. Cool times are when the hot dunked metal is needed to boost what the sun may be unable to accomplish directly. There can be a wall facing south specially built not far outside the house, reserved for showers, and everyone can have their own deep tank against that wall. One tank next to the other is excellent for keeping heat. At the end of the day, the owners use whatever they manufacture in heat for their own shower; if the owner beside you wants to be lazy that day with their tank, too bad, they can't have your water, at least not for free. You could probably have a one-hour slave for one gallon; imagine what you can get for three.
Okay, so now you have drawn plans for a communal shower room built in the sun right beside a row of tanks on its southern wall. When building my house, I had a small 4' x 4' shed acting purposely as my shower stall; in the cooler months, "showers" could be arranged at peak afternoon temperatures, appreciated when the air temperature outside is well under 70 degrees. It could be as much as 20 degrees warmer in the shed (but only when sunny). But my showers were with a container over the head, not from a shower head.
Your communal shower could have an insulated mixer-tank on the roof fed by a pump taking water from the deep tanks. It could be a very small pump.
Generally, showers in summer are not a problem, meaning that solar systems should be geared more for cooler seasons. It will take longer in the cooler seasons to warm water, wherefore there's an argument to be made for facing both the tanks and shower stall toward the south-west for maximum heat in late afternoon.
If for whatever reasons you opt not to locate tanks directly beside one another to keep heat loss at a minimum, three mirrors per tank can be very useful because the sun is lower all day in the cooler seasons. Have the mirrors mounted to plywood for longevity, and arrange hinges in the plywood so that the mirrors can be swung...for setting them at any angle of your choice. For example, when the autumn/spring sun is at noon, a tank facing south no longer receives light from the east, wherefore a mirror on the tank's east side can capitalize to deflect light to the black collectors on both the tank floor and tank back. In the morning, the mirror on the west side can be used in the same way, and a third mirror on hinges over the tank can be the noon-time deflector. Adjusting the mirror angles every couple of weeks will become routine. There needs to be a method to lock the mirrors in place to protect against wind.
Another idea is to have one tank (not sealed, with air hole) on a south wall collecting early-day heat, and another tank, sealed water-tight, on the west wall right around the corner. With the south-wall tank located higher than the other, it can drain naturally to the sealed tank out of which waters are taken. With tanks facing different directions, their differing temperatures can be used often to an advantage. Thermometers fastened in/to each tank seems like the thing to do.
The benefit to having tanks on the ground is that one can shift them. Instead of having two tanks as described above, we might use one tank alone on wheels upon a wood patio floor. Just wheel it from south side to west side. Face it east at dusk so that's it ready to maximize heat collection from the break of dawn. Bonus. But for this method, you'll need flexible hosing acting as the pipes to get water in and out of the tank...unless you're using buckets.
But wait. Why use wheels, such an old invention? Why not build the tank on a platform that spins easily around...like a merry-go-round. To make this happen, drill a 3/8" hole in the center of a solid metal rod about 2" in diameter. Stick or hammer tightly a short 3/8" metal rod into the hole, allowing it to protrude an inch or less above the rod. The entire weight of the tank will be spin on this 3/8" pin.
Insert the lower end of the rod/pipe into some concrete in the ground (same as one would for a fence post). Let the 3/8" pin be about three feet off the ground.
Beef up the diameter of the rod/pipe with telescoping pieces of larger pipe slid over it (you can streamline this method as you think best). The inner pipes don't need to be metal, but the last one (minimum about 4" diameter) should be metal or tough plastic; grease it on its outer side. For the final pipe (pipe walls should be at least 3/16" for welding purposes) aside from the greased one above, weld a thick cap into its top. The thick cap can be a small piece of solid rod that slides snug into the pipe.
Before welding in the cap, drill a hole at least a 1/4" deep directly into the center of the cap, assuring that the cap is welded directly in the center of the pipe. This hole should be slightly more than 3/8" to snugly (but not tightly) receive the 3/8" pin. For best results, shape (with file or small grinder) the top of the pin to match the shape of the drill bit that made the hole in the cap. Grease the hole so that the pipe with cap spins easily. Eventually, for maximum performance, the pin will take on the exact shape of the end of the hole. (If you like, you can purchase industrial ball bearings to make the spin easier.)
The pipe needs to be somewhat thick-walled for welding pieces that form a platform upon which the tank sits. In such a design, the tank might best be highly vertical so as to require the smallest width possible for the platform. The further out the weight on the platform from the central pipe, the higher the leverage due to weight, and, therefore, the higher the possibility of breaking the weld joints over time.
If we think this is too much work and expense, let's try to understand the added energy to be obtained day after day. Perhaps every trib-retreat designer should have a welding machine and a metal grinder for the planning stages. The metal pieces (square tubes make sense) acting as the platform frame need to be applied in a triangular shape, with the horizontal pieces (six or eight in all) welded to the central pipe about three feet off the ground. Each horizontal piece needs a longer piece welded directly under it and extending to the ground area of the central pipe (thus forming the triangular shape). The frame and platform are complete when a round/octagon top plate is welded or bolted to the horizontal pieces.
The three-foot space below the tank can be covered with plexiglas for obvious reason. A spinning tank like this can yet incorporate the three mirrors. It's greatest weakness is heat loss in all directions of a 360-degree circle...unless a back wall is built on the platform to both catch and retain heat. If the tank is to be directed generally at all times at the sun, one could even include walls on both sides of the tank, where mirrors can be affixed without hinges. This seems like the best design by far, to be outdone only with an automatic sun tracking system. But wait; are not our arms a miraculous sun-tracking system that merely need to spin the tank every two or three hours?
The local man who sells junk annually may have plenty of old windows (maybe mirrors too), and perhaps some aluminum frames for windows, or metal from many things. Cut the metal parts into sections to heat your water. On the worst sun days, it may be useless to dip metal into the tank. However, if one, after removing a small bucket of water from the tank, can increase its water temperature by five, ten or fifteen degrees using heated metal, it would be a big deal. For this purpose, the sun often pops out for a couple of hours on mainly cloudy days.
Suppose we arranged several flat aluminum sheets about 16 inches square, each piece connected to the other by typical small cupboard-door hinges that you can pick up for a nickel each from Mr. Junk Yard. The aluminum sheets on hinges can be unfolded into a long string of sheets for soaking up the sun. When they're hot, fold them back up to the size of a 16-inch book, and dunk them. Thanks to the slight thickness of the hinges, a small space between each sheet allows water in to suck the heat out much faster. It's a miracle. There's no use asking God for free energy because you have it already.
On cool days not yet warm enough for the wood stove, we could hang the hinged aluminum sheets as our "curtain" on a sunny, inside window of the house. We could prepare warmed waters inside the house just like that. We could get the ladies to sew us up some deluxe pail warmers in return for making them the aluminum curtains. There's bartering to be had here.
With the cheap glass / windows we can purchase from Mr. Junk, we could turn the shower room into a sunroom, and even sit water-filled buckets or tanks in front of the windows. When you have time in the trib, providing you get the materials in time, build a fireplace in the shower room to warm water in winter that also warms up the shower room. There is no end to the miracles that our bodies can create due to the miracle of sufficient intelligence.
If it's cold in the shower room, say 50 F, sun shining on buckets / tanks through the windows isn't going to help much...unless with our intelligence we box the tanks in their own insulated space, accessible from the shower room through pipes...or cupboard doors that we can get from Mr. Junk for a dollar each, hinges included. But only as supplies last.
The world has been going through a whacko amount of material things this past generation, due only to the government-borrowed billions and trillions that lavished on the peoples much extra money we wouldn't otherwise have had. Much of the stuff is now up for re-sale, precisely due to going out of style in a spoiled generation, at second-hand used stores that will soon become the second homes of post-tribbers, especially as many of these stores are operated as Christian missions.
I kid you not, that while cleaning a customer's garage of "junk," I took a truck-load of some very good items to the local Christian second-hand store, only to be completely refused because it wasn't good enough, and because the store was already piled too high in better items. Horror of horrors for the post-tribber, the people are taking their refused possessions to the garbage dump instead, where we won't be able to get to it.
Some second-hand stores are higher-end than others, but Mr. Junk is a gentleman that we should definitely check out. If ever there was a cheap item worth millions, it's the lowly washer. Have plenty of them in all sizes, even if only one ends up rewarding you well. Solomon missed that proverb.
I don't know what your wife's going to say about me trying to turn you into a garbage collector, so maybe you could build a small garage for the purpose and put a sign on the door, "For Men Only, Obscenities Inside." Or, the attic is a wonderful place for goodies from Mr. Junk. I have been saving containers, flattened boxes, and plastic bags of all sorts in my crawl space (for others who are not prepared), and brought home several mirrors from that garage that was cleaned out. I'm also saving my old clothes for trib purposes, holes or no holes.
The speed of heat transfer through a metal is not the only concern when heating water with metal. While copper and aluminum are good heat conductors, other metals may be able to retain more heat volume per metal volume. The so-called "specific heat" value of aluminum, copper and iron are roughly the same; see table at website below with numbers 24.2, 24.47, and 25.1 respectively for those three metals. The specific heat is the amount of heat absorbed by a certain mass of material to increase its temperature by a certain amount. So, if a pound of aluminum versus a pound of iron both require roughly the same amount of heat absorbed to increase their temperatures by one degree, which metal is the best for use in heating water?
On the one hand, iron is best because a cubic inch of iron weighs more than a cubic inch of aluminum. Iron is 490 pounds per cubic foot, or 7.65 times the weight of water. Aluminum is only 2.7 times the weight (of an equal volume) of water. It means you'll be able to get much more iron into a bucket of water per dunk, and therefore more heat. On the other hand, if aluminum heats up faster, you'll be able to dip it into the water more times daily. It all depends on which method you like or need, the multiple dips daily, or the single dip at shower time. "Single dip" doesn't mean you can't have more than one load of metal for dipping at that one time. Instead of aluminum sheets, you might try sheets of galvanized steel, much less expensive (the glaze over galvanized steel is zinc).
The thermal conductivity of aluminum is 237 units verses 80.4 for iron versus 401 for copper (these figures are for pure metals). Copper is the metal of choice for the multiple dips, and even has a higher density (8.96) than iron so that it's better for the one-dip method too. It's a hassle to dip multiple times daily, but then starting a fire takes about as much time...but uses wood and makes the water container black / sooty. Longish lengths of copper pipe slip into a tank is easy. If we drill holes through the pipe and string in some metal wire so all pipes are attached, several pipes can be handled at once for dipping.
Here's another idea. Poke several copper tubes / pipes (10, 15, the more the merrier) through holes in the bottom of the tank, sealing each location against leaks. Yes, it's expensive, but it captures warmer water on cool days, and we all enjoy capturing illusive things. Each tube in the water must rise up and then turn down though the bottom of the tank so as to form a natural air flow (through the tubes) under the motivation of heated air under the tank. The lower ends of the tubes, painted black, extend perhaps three feet below the tank to catch sunlight. Below the tubes is a black-painted metal plate catching sunlight. The plate and tubes are enclosed in a small space. It will get hot in there, with hot air rising though the tubes, loosing its heat to the water, then falling down cooler back into the space below the tank. Plus, heat will transfer into the tank water through the copper material. No dipping of metal will be necessary on many days.
The question for saving the expense of unnecessary tubing is: how long should each tube loop be in order to pass most of the heat in the tube air to the water? It's a difficult question. Two things we know: 1) when the water is coldest and the air is hottest, heat transfer is quickest; 2) when the tubing is horizontal, heat transfer is quickest. Therefore, going up into the water only a few inches with the tube, then turning it horizontal a long ways, or even the entire width of the tank, is a good idea.
The thinner the tube wall and tube diameters, the faster the heat transfer. The thinner the tube diameter, the greater number of tubes necessary. The more hot air that's removed from below the tank, the faster that sunlight can replenish it, which is why we shouldn't spare the tubes. Good news: there needs to be only one large hole-and-pipe in the tank bottom per the multiple tubes joined into it. A 1" copper pipe (having the volume of four 1/2" pipes) entering the tank can be tee'd off into four 1/2" pipes (running along the tank bottom), each of which can be tee'd off to four 1/4" flexible tubes. You can thereby have one mean heat-exchanger in your tank. You'll need two 1" pipes through the tank bottom, one being the hot-air inlet, and the other the cooled-air outlet.
The great thing is, the law of gravity won't allow a flow of air in the pipes when the water is hotter than the space below the tank. A heating system like this deserves an insulated lid, and an insulated back side to minimize losses from your hard labor in making the heat exchanger.
Vertical heater tanks versus horizontal heater tanks, what's the difference? Heat rises, meaning horizontal tanks lose more heat than vertical tanks. Vertical tanks collect less solar rays at a July noon than horizontal tanks. Those are about the only differences, but quite significant in the heat-loss department. Therefore, vertical tanks will be incorporated in the design to follow. I've decided to locate that design in the next chapter as this one is long enough already.
Fastening All-Sheet Tanks
Before ending here, it should outlined how I'd build a deep, aquarium-like tank with all-plastic sides, three sides and the lid being in transparent plexiglas. For each joint, the entire widths and lengths of the plastic sheets need to be drilled many times (every 3" ?) with 3/16" holes to receive short 1/8" bolts on rubber washers. The holes are for holding angle-iron strips on the outer side of the plastic sheets. All angle-iron must be flush with the plastic edge. Rubber gaskets then go under both the plexiglas and the angle-iron. All angle iron must then be bolted additionally to an adjacent plastic side. From this information, you should be able to figure it out. As a further clue, make, for example, two sides of the tank, plus the bottom side, 27" x 24", but the other two sides should be made 24" x 24". The extra 3" on the three sides is per 1 1/2" on either side for bolting in the angle iron strips.
Aluminum angle is best because it has a thermal expansion rate closer to the plastic than does iron. The coefficient of aluminum is about .000023 inch per inch of length, per degree F in temperature increase. The coefficient of plastic and plexiglas, discussed in the last chapter, was between .000033 and .000055. Over the 24" width / length of the tank, expansion distances are minimal -- about .045" on each half of a plexiglas side -- over a 70 F increase in temperature. The aluminum will expand about half that distance so as to make the plexiglas expansion that much less problematic.