Solar water panels, can I use after Anti-Freeze for pool

[wooferhound]

I have recently recieved for free, 2 solar water heating panels and some other stuff including some water pumps and heat exchangers.





This system was a closed loop system on the panel side, and used Anti-Freeze to keep the system from freezing in the winter. I am thinking about using these panels to heat my pool water in the Spring and Fall here in Alabama. My question is...

Since these panels were used with anti-freeze, should I worry about using them to heat my pool water directly ?



W o o f -=(

[terry5732]

Ethylene glycol is bad stuff to drink but highly water  soluable. A simple rinse with water should remove enough to not be of any concern. The chlorine in the pool water will completely destroy any remaining traces.

[Ungrounded Lightning Rod]

However the chlorine in the pool water may also destroy the plumbing in the panels.

What's the pipe in the panels?  How about the fittings, etc.?

If the pipe is something that might be subject to corrosion, you can still use them - with a heat-exchanger and a second pump.  Then you can use them with fresh antifreeze inside them to protect them from corrosion, just as they were intended, and never sweat it.

You can make a heat exchanger out of a couple hunks of copper tubing of two different sizes and some fittings.  Use several feet of a larger outer pipe with a T on each end, feeding it from the base of the Ts.  Put a reducing fitting on each end to the size of a smaller pipe and run the small pipe straight through.  (Then you don't have to worry about leaks:  The inner pipe is continuous for the entire length it's forming a barrier between the two fluids.)  Actually:  make two of them side-by-side and hook them in series at one end, feeding them from the other end.  That way they can expand together without much stress on the attached plumbing as the temperature changes

Wrap the whole thing in insulation.  Run the pumps so that the fluid flows in opposite directions.  Shazam!  You have a "counter-current heat exchanger", a very efficient device that nearly swaps the temperatures of the two fluids.

Alternatively, take a water heater, temporarily remove the cover and insulation, and solder a coil of copper tubing to the metal tank.  Pump the hot solar fluid in the top and out the bottom of this coil and you're doing the same thing - in a device that you can also run as a normal water heater "when the sun don't shine".  (This is also a low-cost way to convert a water heater to solar or solar-plus-whatever-it-used-to-be.)  Copper, solder, and the tank's metal all conduct heat very well, and you have all three separating the antifreeze-laden solar panel fluid from your drinking/washing/pool water.

Don't forget to include an expansion tank and a pressure relief valve in the solar panel's plumbing circuit.  Otherwise you'll blow something the first time the sun hits it.

[PaulJ]

   The antifreeze is probably polypropylene glycol, not as toxic as ethylene glycol (check it, though, it might not be). You still wouldn't want to drink it, but diluted into a swimming pool it shouldn't be too much of a worry. In Australia, polypropylene glycol is usually dyed blue, ethylene is usually green or sometimes red, might not be the same where you are.

   If you're planning to drain the panels in winter, some sort of cover would be a good idea. According to the instructions that came with my solar HWS, an empty panel can get hot enough to warp, crack the glass, damage the internal pipes etc even in winter.

   

[TimV]

Very informative Lighting Rod.

Do you have diagram of this type of heat exhchanger posted somewhere or know2 someplace I can see one? One picture to this "densehead" is worth thousand words!

I think I have seen someting similar as and add on for heating water from a wood fired hot air furnace.Thank you TimV

[Ungrounded Lightning Rod]

I couldn't find the original article but here is a link to one I did find.

The first diagram is close to what I was talking about.  To convert it to what I meant:

 1) Delete the reducers shrinking the inner run - just extend the pipe.

 2) Flip the reducers between the large and small pipe around so they point out rather than in.

 3) Solder all the fittings together.  (The diagram shows screws or rivets.)

And to double it up:

 4) Flip the T on the left side over so it points up rather than down.

 5) Put an elbow on the left end of the inner pipe so it also points up, just beyond the T.

 6) Make another one.  Position it above the first, and flip it so the pipes on the left are pointing down rather than up.

 7) Join the left sides together with short hunks of large and small pipe.

You end up with something like this:



                    |

                    V

     _____| |

  ,<_   _____>=  ->

  |  | |_____

  `<_____   _>=  <-

                   | |

                    |

                    V



[Ungrounded Lightning Rod]

I give up.

I accidentally hit the post button while trying to change the formatting options to see if I got the typewriter picture clear.

I tried a number of combinations of HTML tags and formatting settings but couldn't get it to do a monospace font.  The accidental post was about as clear as anything else I was able to construct.

Hope it makes sense.

[NEO]

I dont think its screws or rivits in the UK you can buy "Yorkshire" copper fittings they have an expanded grove pre filled with moltern solder and alowed to cool  supposed to help make a better joint by getting the solder right to the point of where it should be...least I think that the theroy

Neo