Black tubing solar heater?

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Pogo

Pogo

0
May 8, 2009
48
Hello. I'm in East Texas. There is still plenty of heat in the sun but of course the days are shorter.

Two things; First, will a solar blanket at night help hold the day's warmth?

But, my main question is about pumping the pool water through black plastic tubing for solar heating the water. I have a fence right behind the end of the pool and pump that catches direct rays of the sun from about 10AM on. With that in mind, what would be the best diameter tubing (as mentioned above above or other) and how much (length of tubing) can I effectively use?

My local Lowes has 100' rolls of 1-1/4" tubing for $54 and 1" tubing for $29 with option of $25 for 3+ rolls. Obviously, the smaller tubing would be a good savings if I can use it.

My pump is good for .about 90/gph (tag is partially worn off) in a 23,000/gal in-ground, vinyl lined pool.

Finally, about how much increase, ball park, in temperature can I possibly hope for on an ideal day? ("ideal"= sunny and temps in upper 80s/F. in 7-8 hours sunlight.)

Thanks for any help that can be offered!:D
 
Solar blanket will get you the best bang for the buck. Use the search function for homemade solar heater or something like that, maybe poly tubing. You'll get lots of hits. It doesn't work. Me and many others have tried. And if you are absolutely sure it will work, spend the money on black garden hose. Then when you give up, you'll have something useful leftover and not a bunch of plastic tubing.
 
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Hello Pogo,

+1 To answer a portion of your questions Yes the solar cover should help. There is another feller on here who also lives in Texas who is reporting that his temperatures with the solar cover on are remaining at "85 during the night, and 91 during the day". Here is the link for that his temps are located in comment #6 : http://www.troublefreepool.com/threads/105259-Solar-cover-left-uncovered-some

Also when a cover is placed on you might need to ensure you keep your FC levels at 1-2ppm higher to ensure you don't start accumulating Combined Chlorine, and end up with an eventual algae bloom because it seems that with the cover on it causes the environment under it to be just right for that to happen at times. Also be sure and remove the cover occasionally to allow your pool to breath, otherwise, happy swimming in your nice posty toasty warm pool.

I'm sorry I can't offer any assistance on the black pipe other than knowing that some people do use them, so perhaps someone who does will come along and offer you assistance to know what size would work best for your intended purpose. EDIT: I see Richard above was able to offer you suggestions in this area).

I hope this helps and have a wonderful day. :)
 
Yes, to the solar cover, as to solar heating in our climate, it seems to work well until a week or so after the first freeze of the year for me, or say mid November in a typical year. After that point the pool cools rapidly as there is simply not enough energy left in the sunlight to warm the water unless you have a massive solar heating system. As to making a home made solar heater from black poly tubing, I too have been there and done that, and I can tell you the commercial flat black panels beat anything you can make yourself hands down in all respects. They will perform better, be easier to install, last longer, and most importantly put out way more BTU's per $$$ of investment.
 
I tried black garden hose style water heater years ago at my previous house pool. Something like 200' of black rubber hose, decent flow diverted off from the pump. The temp increase at the hose outlet was noticable, but a drop in the bucket compared to daily solar heating and nighttime cooling. Also, it looked very redneck. (sorry, don't mean to offend any proud rednecks, its just an expression). It wasn't pretty. And it was a hassle to pick up for parties, etc. On the bright side, I still have some of that black rubber Craftsman garden hose 15 years later. So, it wasn't a total loss.

-R
 
Solar heating is all about sqft of exposure to the sun and the flow rate (high is better) through the tubes.

A 100' roll of 1" pipe is a little over 8 sqft. One 4x10 solar mat is 40 sqft ... so do the math ;)

Generally one wants 50-100% of the sqft of the pool surface area depending on sun exposure and goals. Most pools are at least 400 sqft .... so a minimum would be 200 sqft. So you would need to wrestle 24 of those 100' section of pipe and build a manifold so you could run through them in parallel. So that is $25x24 = $600 before fittings.

You can get 40 sqft solar mats off Ebay for $80 ... which would be much more efficient.

FYI, I had 2500' of 1" tube on the roof of this house when I bought it, that was at most 200 sqft (likely less since it was not well organized and a rat's nest). It worked OK when I was not fighting with leaks. I ripped that out and now have 500 sqft of good solar mats that I installed that I got off Craigslist.
 

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jblizzle said:
Solar heating is all about sqft of exposure to the sun and the flow rate (high is better) through the tubes.

A 100' roll of 1" pipe is a little over 8 sqft. One 4x10 solar mat is 40 sqft ... so do the math ;)

Generally one wants 50-100% of the sqft of the pool surface area depending on sun exposure and goals. Most pools are at least 400 sqft .... so a minimum would be 200 sqft. So you would need to wrestle 24 of those 100' section of pipe and build a manifold so you could run through them in parallel. So that is $25x24 = $600 before fittings.

You can get 40 sqft solar mats off Ebay for $80 ... which would be much more efficient.

FYI, I had 2500' of 1" tube on the roof of this house when I bought it, that was at most 200 sqft (likely less since it was not well organized and a rat's nest). It worked OK when I was not fighting with leaks. I ripped that out and now have 500 sqft of good solar mats that I installed that I got off Craigslist.
Click to expand...

aha that is how the math works tyvm. I have been playing with solar using 3/4" black poly pipe for the past few years, last year it was keeping up rather well, this year I doubled the amount of water I wanted to heat, while only adding another 100' of pipe. I have 3 loops now 170' per loop in an enclosure, heat/cool thermostat determining the "on" time, it helps but I need to put it on the garage roof and plan on adding 1 or 2 more loops to it when it does go on the roof. The enclosure covered with shrink wrap I think helps get my minimal sq footage up to a usable amount. Enclosure is roughly 17' x 5'. Thinking about this I am probably going to go with 5 loops in the enclosure next year (510' of pipe), as I noticed going from one 510' loop to 3 170' loops helped a lot. Solar 'mats' are looking at about 2-300$ up here in Canukistan.
 
I wonder if you went to a smaller diameter thinner walled piping if the heat exchange would be better. Also, have you experimented with pump rate? It seems to me that a slower rate would have more time to absorb the heat. All this is conjecture on my part. But I am seriously thinking of trying my hand at this, if just for the fun of it...
Or maybe think about crushing the piping so it's almost flat. That way the cross-section would be greater in the direction of the sun. Would help with radiation loss during cloud events.
 
I was thinking a slower rate would help with the heat. But it takes 1 BTU to heat 1 pound of water 1 degree F, so by doing my measurements this year I found I could fill a gallon pail in about 5-6 seconds (510' loop) yeilding approx 28,000 BTU per hour. seconds divided by 3600 x 10 (gallon of water weighs ten pounds)x temp rise (4 degrees ). Once I went to 3 shorter loops my temp rise dropped 1 degree but my flow rate stayed the same if not went up. So if you do the equation, time divided into hour in seconds (3600) x 10 x degrees temp rise it works out better with more flow just as Jason said above. Time of 5 seconds and 4 degree temp rise, versus time of 4 seconds and temp rise of 3 degrees X 3 loops. 28,800 BTU versus 81,000 BTU. 81,000 BTU is nice but below the bare minimum to do what I am trying to do which is heat a 24' x 52" AGP.
From what I am reading minimum 100,000 BTU boiler to do what I want, so more loops. I am using a 3/4 hp 2500GPH pump to circ my heat circs when filter pump isn't running.
Looking back it is enclosing the piping almost like a 'solar mat' plus making more loops has given me the highest return on BTU gain. I have used thinner corrugated pipe but it doesn't last like the regular PE underground sprinkler pipe arranged neatly in a sealed box.
 
Enclosures can help you capture more heat with less pipe.

You will add more heat to the pool with higher flow rates. Better to heat a lot of water a few degrees than a little many degrees. The warmer the water, the more heat you will lose back to the environment.

If the tubes are not cool to the touch, then you do not have a high enough flow rate.
 
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