Solar Water Heater

[Jake] built himself a solar water heater. The system has an 82 gallon insulated water tank and uses a solar collection grid made of PVC pipe. As the water heats, it rises to the top of the collector and runs into the tank while pulling colder water from the bottom of the tank back into the collector.

A sunny day yields temperatures around 130 degrees Fahrenheit. On a cloudy day the water can still be heated to about 90 Fahrenheit. This is about 19 degrees cooler that one might desire but the difference is made up by an electric shower head that heats as the water comes out. [Jake’s] system, seen in the video after the break, allows him to forgo the use of electricity on sunny days, and reduce its use by around half on cloudy days.[youtube=]

49 thoughts on “Solar Water Heater

  1. it’s great that he shared this video. i would be curious how much it cost him for the whole system.

    also, for north america (canada), i would be interested in ideas for closed systems with heat exchangers, if anyone knows of some good online resources.

  2. Agreed with Tantris about cleaning out the fluorescent tubes, that just can’t be good for your health or the environment. Good job overall and especially given the limited resources probably at hand.

    The temperature rating though has less to do with the joints than the strength of the actual PVC pipe. Its a plastic and plastics weaken/deform with temperature. Although your pressure SHOULD be low enough, you may run into leaks etc as pipes expand/sag. Also, not sure if there would be any leaching issues at higher temperatures overtime, especially depending on the water makeup.

  3. yes try northernsolar. but it is simple to build your own. use his plan for the solar heater but use 50/50 antifreez water in the heater. get a big 40 to 50 gallon water tank. insulate the hell out of the tank. get two coils of pipe made that fit together in the tank one coil for the solar heater and the other for your water. plumb the water line before the old hot water heater. fill the new tank with water and put the lid on. put the safty presser releif valves on the tank too. ground both lines if you use copper pipe. replace you old hot water heater with an instant or on demand for more savings if you have the money

  4. Two points to keep in mind: 1) it is easy to accidentally overheat your water or your thermal array, so keep it underpowered like this one is. Or things can explode.

    2) In many places, it is illegal to do this without a licensed contractor performing the work.

  5. Sadly I don’t think this can be put to use in the cold weather of Canada. Snow accumulation on it would stop it from working.

    And The Cheap Vegetable Gardnener, I dont think you’d have problems with any home owner associations except if its a coproperty. And even if you’d got a letter, no judge would force you to remove it because it’s ecological : that would make a really bad press for them!

  6. A more effective system would uses copper piping painted flat black (transfers heat more efficiently), with glycol (in case of freezing), and transfer the heat using a water-water heat exchanger.

  7. Two words: Legionair’s Disease.

    An interesting fact for solar use, Phoenix Arizona has almost zero penetration of solar water heaters despite the brightest and most sun in North America. This is because most hot water in the home is used -after dark- (think about it)and it is simply not economical to invest in solar panels and pipe etc. for the minor amount of “free” energy that actually gets used. The average home will get one tankful heated by solar per day, but use much more than that. The majority is heated electrically.

    Food for thought.

  8. @werfu, probably true though I know the association has gotten complaints about ridiculous things such as simple trellises. Fortunately those complaints were ignored as just rumblings from an old man who apparently was slighted by a trellis back in the day.

    I do like the ecological angle, I remember when I lived in Colorado it was illegal to have a rain barrel due to the fact that another state had rights to the water hitting my roof though never heard of anyone being prosecuted for it.

  9. We built something similar for our pool here in Ohio. We used a tractor radiator though. Built a wooden frame to hold it and put a plexi window over the top. Put it inline with the water filter. On really sunny days when we forgot to open the valve to the collector it’d blow steam for the first couple minutes. It’d get us on the pool about a month earlier than without it.

  10. @The Cheap Vegetable Gardnener i never heard of home owner’s association however if you are renting or live in a gated community (a community for rich people or something) you may have to get permission to put up anything like that because of the eyesore factor.

    @craig i never heard of any legal issues unless city code for experimental stuff

    @ The Phantom as far as i know of Legionair’s Disease is only an issue for open waterfall cooling systems that are exposed to the elements like the cooling systems used in older industrial air conditioners and nuclear power plant cooling towers.

    birds deposit their Legionair’s infected droppings in and around the waterfalls and it gets sprayed around.

  11. who the hell decided it was a good idea to use electric shower heads? wow… that’s retarded. really.. of ALL the ways to heat water… that is not any kind of intelligent. :-p

  12. @noone

    Hey, don’t knock the outhouse! I know plenty of people that still have them. Most of them don’t have running water for one reason or another, and have to haul the water in 200 to 500 gallon tanks from town. Let me tell you, blue foam insulation is your best friend when it’s -40F and you have to use an outhouse. No, not for insulating the outhouse, you have a blue foam seat to go over the outhouse seat that you take with you from the cabin.

  13. @ The Phantom

    You obviously don’t know much about solar. Solar tanks are very well insulated and only lose 2 to 4 degrees (F) over a 24 hour period. Many systems are able to heat 80 gallons of water 40 to 50 degrees (F) in three to four hours. I have used several different kinds of these systems and they all perform close to, if not beyond, what I stated here, even in the middle of winter!

  14. @ ThePhantom, re Two words: Legionair’s Disease.

    That’s FUD. Legionnaires is only an issue for evaporative air conditioning systems.

    Whatever is causing Phoenix Arizona to not be using solar hot water, it won’t be the fact that hot water is used after dark. That is also mis-direction.

    These systems are called hot water *storage* systems for a reason. The water stays hot all the way through the night until morning.

    It is possible to add an electric or gas booster to the systems, for when there is not enough continual sun.

  15. my water heater is all natural. i just throw these special rocks into this collector, and they get hot. that heats the water and provides pressure. this guy with this clicky noise thing called my rocks ‘uranium’ whatever that is. i guess it means ‘rocks that get hot when you put them together’
    well since i found the rocks in the ground, it is an all-natural water heater.
    far more efficient than electric shower heads.
    previously i had to build a fire to heat a metal pipe that ran into the house. that was my hot water pipe, but i think using these magic hot rocks is much safer.

  16. @werfu: Regardless of bad press, it’d still be breach of contract if solar water heaters are explicitly prohibited by the covenants, conditions and restrictions. You may not have to remove it, but you’ll definitely pay for it by means of fines, etc.

  17. TWENTY EIGHT posts and no one has mentioned that fluorescent bulbs are full of MERCURY VAPOR!

    This entry is meant for the Darwin Awards. Your going to go out of your way to poison the water in your home?

  18. @ Mr. Ruger

    The fluorescent bulbs aren’t filled with water, they are just surrounding the PVC tubes. This acts as both an insulator and it absorbs the suns rays more efficiently than the PVC would alone.

  19. @grovenstien: 60C is 140F. The effective max temperature for this system is stated to be 109F (which is reasonably hot for water). Anything over 125F, I’m told, can scald (No personal experience there though). Concern for legionellosis is not unfounded in this regard.

  20. I’m actually a solar thermal engineer. I’m going to plug my 2 cents in here really quickly. Although I applaud the effort and creativity it really is a bad design and I doubt it’ll last long or provide reasonable hot water. Mentioning how hot the water comes out is a useless number without mentioning how much of it. The use of old mercury tubes just sounds like a bad idea. Legionella is a problem with all hot water systems particularly with solar hot water systems. It grows at the bottom of the tank where there is stagnant warm water. Just because the top of the tank is 140F doesn’t mean that the bottom will be. Fortunately, the Legionella problem is quite easy fixed but it seems mostly only European manufacturers fix it. I wouldn’t recommend building your own system without addressing that problem properly.

  21. Quote from the article = “While I was taking apart the bulbs I used a mask and was sure to wash my hands afterwards, since I have heard that they contain dangerous chemicals.”


    I think the point of this article was the fact that it was made for a children’s home very far from civilization and domestic water supply that we take for granted here in the states.

    I applaud the guy’s ingenuity but wouldn’t apply the same construction to a household here in the states for several reasons.

    As far as efficiency goes the best thing you can do is increase area, increase area and increase area.

  22. @Mr. Ruger and JR

    I have never seen anyone complaining about mercury vapor and metal halide tubes yet they contain 100 to 1000 times more mercury than fluorescent tubes.

    @The Phantom: a simple solution for the Legionella is not to use water in thermal collector and storage tank. someone mentioned 50/50 antifreeze water mix. the pipes running water trough tank can do heat exchange.

    @bancroft: check out this cool thermal siphon heat storage at conosolar:
    it look easy enough to DIY.

    @Jake: make a scratch around the glass tube and heat it with hot red glow wire. that will make glass crack along the scratch, so that you can have flat cut off glass tube.
    nasty dust contains mercury. wipe the pipes with wet sponge, put it in a glass jar and cement it. store far far away in dry desolate place. ;)

  23. The correct way you should build a water heater is to use the water in the tank as a heat reservoir only, and not let it come into contact with the actual water you use.

    This means that there’s a copper pipe coil inside the tank that is surrounded by the water, and any cold water entering the coil will be heated up before it exits the other end.

    That way it doesn’t matter if there’s bacteria growing in the tank, as long as they’re not growing inside the copper coil, which is pretty difficult since it gets completely flushed out with fresh water regularily.

    I find it unfathomable that someone would still actually use a water heater as a hot water reservoir and allow the water to be used to wallow in there for god knows how long, because it will never get fully flushed no matter how much water you let out of the tap. There’s always some nook or crevice inside the tank where the bacteria can hide.

  24. @Mark Richards: mercury vapor diffuses in to the phosphorescent coating. that is why fluorescent tubes dim as they age. it is safer to cut open old used tubes than new ones . i have cut more than 100 tubes so far …

  25. this works in northern ontario in the winter. I have seen it in person. one panel can cut your heating bill by up to 60% and you can put many of them together to heat you house as well. I like the geothermal idea. geothermal is highly efficient to begin with and now you ad free solar heat to it in the winter. Thats a plan

  26. Thanks for the comments on my heater – Here are some replies (sorry for the long comment)

    @bancroft – The total cost: (USD)
    $100 (about) for the plumbing parts.
    $80 for the water tank
    $200 for the glass
    I paid some bums 50 cents for each bulb (they go through trash anyway)
    Pretty Cheap!

    @PsyKotyk – Copper – It would be much better, however with the price of copper in Brazil the copper alone would have cost more than the entire setup above

    @HackJack – Electric Shower Head – its 220v. What I did not mention is that it goes up to 7500 watts. Thats 34 amps above my head while I shower. And most showers I have used are not grounded… Only been shocked a couple of times…

    @space – Thanks for the tips, I will be sure to try it!

    Thanks for the comments!

  27. One more point –

    Living in this part of Brazil means taking some health risks.

    In the video you can see my roof, its asbestos – and I *cut* some of it.

    Our water source is a surface well in a swamp, the swamp is fed by *field run off*.

    I wore a mask for asbestos and we have a filter for the water – so I am comfortable running the risk of breaking light bulbs with a mask on.

  28. don’t know why you’re stressing about 40 amps above your head. We’ve just uprated out electric shower to 10.5KW, at 240V, thats 43.75A!!!! Had to get just about the biggest twin and earth feed installed to power it.
    You might say its inefficient, but it only heats water when I need it for a shower. It doesn’t heat water then just let it cool down in a tank (that’s not a dig at solar, rather conventional gas boilers). No smart comments about on demand boilers please, I can’t afford £3K+ to fit a new one, ours doesn’t even heat water any more and was made in the 70s :(

  29. @leccyshower

    The shower heads are much cheaper than the demand boilers. You can get one here for less than $20 USD.

    My problem with them is that few here are grounded. As I said, I have been shocked a few times. Usually the shower heads have a metal pipe that connects them to the wall. Just touching can shock you. Another time the shower head started arching to the wall while I was showering… It ended up leaving a burnt spot on the ceramic tile.

    Properly installed with a GFI I think they would be a great system. But I have yet to see a GFI receptacle here…

  30. @ nachowarrior

    Holy crap you fail. That is no different than a tankless water heater. The only real difference is its capacity. A good tankless can heat enough water for an entire home, while this one has trouble with one shower worth of water.

    The only danger would be in the event that the unit is not grounded properly.

    And yes, everyone who has a background in this stuff can tell you there are better ways. But for a couple hundred bucks and some ghetto engineering it still isnt bad.

  31. Certainly, but everyone needs to realise that adding Solar on their property is an asset that will boost the long term worth of their building if / when they come to a decision to sell. With the environment the way it is going we are not able to ignore any product that delivers zero cost electricity at no cost to both the shopper and more notably the earth!

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