Anyone do a solar DIY pool heater?

[Bogie]

Jen's anemic, and does NOT deal with the cooler pool water, but she needs rehab exercise. What's the best way to bump the temp a bit?
 

[Ron]

While we are waiting for replies from folks that know I have a question.

Can you cover it at night? I bet a lot of the solar heating from the day is lost during cooler evenings.

[charby]

I was thinking some cover that allows light to penetrate and still retains heat.

I remember reading about wood fired hot tubs.

it looked like this one http://www.stewardwood.org/resources/DIYhottub.htm

[Bogie]

May be able to put some sorta floating blanket type of thing on it, but since most of the folks who use it are singularly unmotivated, if I don't put it on, it ain't gonna happen. And I live an hour from the pool...

I mean, sheesh... Some of the kids will just LOOK at something going wrong. They won't get up and try to stop it. They won't go find an adult to (maybe) fix the problem. They just look, because it's not their problem. ARGH! I mean, you'll walk into the john, and the toilet is stuffed. The plunger is right next to it. Has it been used? Sheesh...

People, raise your kids to be self-sufficient.
 

[Nick1911]

Bogie: Problem Solved.

[charby]

Bogie: Problem Solved.

so you make a heater from your skills making a condensor for a whiskey still... and who said rednecks weren't resourceful

[Manedwolf]

Cheapest solution for a warm day is to float a black tarp on the surface during the hottest part of the day, then pull it off and go swimming.

[Bogie]

Yeah, a black tarp would make sense, but given that some dumbshit kid would decide to swim without pulling it off, and remove him/herself from the gene pool, and I'd get blamed for it, I don't think that'll work too well.

[K Frame]

Any chance of finding an indoor pool for her to rehab in?

[HankB]

Is this an in-ground pool? Then painting the concrete lining black would maximize solar absorption.

If the kids are as bad as you say, then anything else I suggest (for example, a solar concentrator heating water pumped through tubing) would potentially be worse than the black tarp already mentioned, due to a need for some electrical connections to run a pump, if nothing else.

[Brad Johnson]

100' of heat-resistant pipe, two 2'x8' sections of corrugated metal (barn tin), a 4x8 sheet of plywood, a 4x8 sheet of 2" hard foam insulation, a 4'x8' sheet of plexi, a small pump, some misc 1x6 planks.

By the way, copper pipe would be best but, as you are aware, is pretty high dollar these days.  You could probably get away with black poly.

Attach the insulated panel and corrugated metal to the plywood (will probably want to use small bolts going all the way through the back of the plywood. Layer it plywood, panel, metal.  Paint the face black using high-temp paint.  Arrange the pipe across the panel using the corrugations as a guide.  Box it with the 1x6s and cover with the plexi (you may need to fashion a few stand-offs or supports for the center). Put the pump on the intake (cool) side of the panel, not the outlet (hot) side.  Use the cheapo foam insul-wrap sticks on the outlet side (mostly for your protection).  Put the pump on a timer to run during the day.

On a sunny day, don't be surpised if the outlet temp is in excess of 120 deg F.  Maybe more.

Brad

[280plus]

Look on the net for ABS solar panels. I have two 4' x 12' panels (can't remember mfg) and they do fine as long as you got good sun. We heat 30,000 gals of water with them. They are undersized for the job here but will slowly build heat over a couple of good days and maintain temp once it's up. I tied them together in parallel and feed them with 3/4" PVC from the discharge side of the filter. I cheated though becasue I just took the outlet and ran it directly back into the pool. Kinda cheesy but the water is warm. 

BTWan uncovered pool loses heat 3 times faster than a covered one.

[roo_ster]

When I lived in Florida, a lot of folks used commercially installed solar pool heaters consisting of black tubing on their roofs.

[client32]

When I lived in Florida, a lot of folks used commercially installed solar pool heaters consisting of black tubing on their roofs.

Is it just looped several times in a big circel around an entire side of the house?

There is a house that I drive by occasionally that has something like that.  I always thought it was for heating water, but never for sure.

[280plus]

http://www.poolwarehouse.net/Catalogs/catHeaters/bv_above_ground_solar_heaters.asp

[armchair warrior]

My folks used to have an above ground pool.
My dad got a cover that was like heavy duty bubble wrap.
He kept that on the pool most of time.
Pool was about 4' deep.The top 1-1.5' would get 80-85*.
After swimmin' around the pool was 75-78.

[280plus]

I've also heard of putting black plastic on the bottom held down by bricks or some such.

[jeepmor]

The redneck heater is actually pretty sound from an engineering perspective.  The application could easily be made more graceful employing all the same principles in a neater package.   You could employ two turkey burners or the gas grill heaters and then have a better metal box fabricated.  Put the pump on the inlet side of those systems.

The ABS plastic angle works well also.  They should be plumbed in series for best effect, this way they get heat input the whole path.  Parallel piping gets you about 1/2 the heat that a series system would simply employing only two units.  Black plastic or coating on the bottom of the tank will help a lot.  Black is the color that absorbs radiation best, but this should be obvious.

Beyond that, it's gonna be some math.  Simply put q = m cp (Tout-Tin)

q - energy flux
m - mass flow rate (remember mass, not volumetric flow)
Tout - Temp out (heater outlet temp)
Tin   - Temp in (pickup temp)
cp - water specific heat thermal coefficient.  Use avg between Tout and Tin.

Based upon this, you then need to know how much heat energy you are putting into the system.  Barring the BBQ example (genius, but hokey as hell) you'll need to know what the solar flux for your area and time of year when you prefer to use it.  You then need to consider your design parameters.  How much room to you have for said system, do you have the ability to face it south, etc.  Then you need an adequate pump to make it all work.  My suggestion would be to oversize your capacity by a factor of 2x or more  and then employ a variable speed pump or some other mechanism so you can throttle the output to acheive the temperature output you want. 

[K Frame]

Friends of mine had a cabin in the woods. They took a medium sized swimming pool and piped it through an outdoor fireplace that they built. Build a fire, turn the pump on, and it would get nice and toasty in a couple of hours.

[280plus]

Series vs parallel panels. Now I haven't done the math but after some experimentation I find parallel panels seem to work better for me. Why? A couple reasons. One, because both panels see the same temp incoming water and therefore have a higher delta T between incoming and air temp. In sreies the second panel sees a warmer temp incoming which reduces the delta T so it will not do as much "work" as it would with cooler water entering. Second, the water flow splits 50/50 which reduces the flow rate through each panel by half allowing it more time to pick up heat on the way though.

[280plus]

Another cheqapo method is to wrap 5 gal buckets in black garbage bags, hang a "anchor" from them somehow (remove the handles because they will rust) and suspend them upside down so they're floating underwater like little mines on the "ocean floor." Long as it's sunny they will heat the pool.