Passive Heat Using Homemade Solar Disks

So that I do not run afoul of the Forum's rules I will say upfront that I have no connection to the pool industry, and that this post is in no way aimed at making money for me or anyone else!

When we first got our pool three years ago I was determined to heat it without using additional energy (already feeling a bit guilty about the general environmental unfriendliness of pools...) so I looked around for alternatives, and was not happy with what I found. Our best bet was a solar blanket, but this wasn't a great fit for us because we have a very oddly shaped pool, nowhere convenient to site a reel, and because our daughter was quite young at the time (I was afraid she would get trapped underneath - *shudder*).

What I did stumble across was a variant on the inflatable solar rings in vogue about four years ago (the kind that rip, blow away and generally are ineffective, from what I have heard). The version I have are homemade rings made of the tubing you use if you are installing drip irrigation, and circles cut from regular pool solar blanket material attached to the tubing with the plugs used in drip irrigation systems ("goof plugs"). The rings can be any size (mine are about 4' across) and for optimum heating/evaporation reduction should cover 75% of the pool surface (mine cover about 60%). The tubing gives the rings enough weight that they don't blow around too much (although the return jets do tend to stack them up after a few hours), and you can swim around them and under them without worrying about being trapped (they don't weigh very much). They stack neatly on the pool deck, and are not unattractive while floating in the pool - picture big blue lily pads. And they actually do serve as refuges for some of the critters that fall into our pool...including frogs!

I would like to make extravagant claims for their effectiveness, but since I only have one pool I have not been able to do any controlled experiments regarding heat absorption/retention and evaporation. My husband and I both feel pretty sure that they help significantly, and are worth the effort. When the days start to shorten, and night temperatures start to drop sharply in late September our disks are no longer particularly effective - they still slow the pool's heat loss, but not enough to keep us swimming. (Our pool is half-shaded, and the angle of the sun in autumn means that there is very little direct sunlight hitting the pool after mid-September.)

The initial cost (three years ago) was about $200 for 36 disks, and all 36 are still in good shape. I plan to make some more this fall to get up to the magical 75% coverage. Theoretically, when the initial piece of solar cover wears out it can be removed from the ring and new material added (I have not needed to do this yet), which makes replacing worn out rings relatively inexpensive.

I have tried very hard to find the person who originally came up with the plans (about 6 years ago, I think) so that I can credit them, but I have had no luck. They titled them "Floating Solar Disks".

Alison

I had not heard of these rings before but am intrigued! We have many feet of drip irrigation tubing that we're not using and this might be a great way to re-purpose it. I would love to see some pictures of how the tubing is attached to the cover disks with the plugs. Do you have any photos online somewhere?

Hi AnnaK

The drip tubing cannot already have holes, or you must plug the holes (with the goof plugs), lest the tubing fill with water (although I doubt the discs would sink, just get awkward to move around). I don't have any pictures online, and I don't think I am allowed to post pictures here yet (ever?). Could I PM them to you?

Alison

You can post pics using Photobucket, Flickr, or Picasa. Or, you can email them to me -- poolforum@gmail.com -- and I'll post them, via the PF Picasa account. (I'll eventually copy them there anyhow.)

I'm behind, though. So posting them initially through your account would get them here sooner.

What Ben said. They would be really helpful to all our members. Please let us know if you decide to post them on one of the sites he mentioned, and mega thanks!

https://lh6.googleusercontent.com/-U...ep%2520end.jpg

https://lh4.googleusercontent.com/-S...al%2520pad.jpg

https://lh5.googleusercontent.com/-E...2520tubing.jpg

https://lh5.googleusercontent.com/--...o%2520ring.jpg

Love these!

In the last picture the edge looks sealed, like you popped the bubbles and then somehow sealed it. Did you, or does it just appear that way? Or did you cut between the bubbles? Is THAT why we learned to stay inside the lines in kindergarten? :)

Thanks for posting the pics Ben!

The fabrication instructions (short form) are:
1. cut a length of tubing that will form the size circle you are interested in making, remembering that Circumference = pi x Diameter. Join the cut ends with an appropriately sized connector ("nipple").
2. drill holes in the tubing circle approximately every 10-12 inches. The holes should be slightly smaller than the thickness of the "goof plugs". Or the holes can be made with the plastic tool that comes with the "goof plugs", but this tends to get a bit hard on the hands!
3. cut out a circle of your preferred solar cover - we chose ours because it was the least ugly, to our eyes. I found it helpful to cut the circle slightly larger than I needed so that I could trim it to fit perfectly after it was attached. This also meant that it didn't matter if my initial cutting was a bit sloppy!
4. with the tubing ring on a hard surface, place the cover wrong side up over the rings and squish the plugs into your predrilled holes. You will probably need a pair of pliers for this.
5. trim any excess cover, or any overhang where the ring distorted while you were messing around trying to get the plugs to go in, and then chuck your finished disk into the pool.

Other things: When you take the disks out of the pool don't put them on grass, or at least cover them with a towel, as the sun will fry the grass in a very short time. If the disks are piling up in the pool because of the return jets you can link the disks together to make a big flexible raft - I use the Velcro tape sold for tying up plants because it is both water and UV resistant. The large headed "goof plugs" are easier to use and theoretically hold the cover on more securely, but they are also much more expensive than the small headed ones. I used a mixture and have had no problems with the small headed plugs so far. You can buy them in large quantities online; everything else is readily available in home improvement centers.

I have detailed instructions (in the form of scanned documents) which go on for pages, if anyone wants them, and if there is a sensible way of posting them.

Alison

AnnaK,
I used that particular pic because you could clearly see the plug - it just happened to fall in the seam where pieces of my pool cover were joined (I cut up a 20x40' to make these; haven't used all of it yet). Most of the plugs hit a bubble, and it doesn't matter in the slightest.

Alison

Thanks a bunch, Alison.

We cut our cover into strips and sections, look at it on our pool pages site in my sig below. I'll be limited with the diameter depending on how wide the sections are. Your instructions are very helpful.

One year we took the cover off the pool, that was before we had cut it, and laid the whole thing out on the lawn to dry. That lawn has never been the same since!

These are really neat. How much heat gain or temperature increase do you think or believe you get?

Quote:

---

Originally Posted by stuckpipe

These are really neat. How much heat gain or temperature increase do you think or believe you get?

---

I am really not sure, partly because for one of the two full summers we have had the pool open we were also using the HeatSavr filled fish, which would confound any results. On late spring nights which are clear and still the night time air temp is often 30 edgrees F lower than the day time high. Without the lily pads we drop 6-8 degrees, with them we drop maybe 2 degrees. We keep our pump off at night, which allows the pads to remain in a single layer (for mazimum coverage) but we still only have about 60% coverage so...

Also, we have a very shallow shallow end (9-10") and a shallow end (22"), as well as the more conventional depths. My guess is that we lose heat from these areas very quickly, especially when the pump is on!

In the morning, before the pump has been turned back on, if I swim under a lily pad that has had the sun on it already (with still water underneath) the water feels significantly warmer (how's that for precision?!) for eight inches or so under the pad.

We stop using them for July and most of August because the water is too warm by then.

Alison