DYI Solar heater

[Searcher]

I may be oversimplifying things but I have alot of room on my property and can run as much black poly pipe as necessary.

Would there be anything wrong with just laying out 1000 or 2000 foot of black poly pipe in a big loop in the field behind my Pool as a solar heater?
I would just create a slip stream off my system.

I have a 24' round ag pool (12,000 gallons) with 1 HP pump on a 200 lbs sand filter.

Does anyone see any issues with this? I'm not sure how much pipe is enough and if there would be any pressure loss issues.

thanks,
JK

Welcome and this is a fun project.

If you are talking about 1,000' to 2.000' of 1" coiled well pipe, you will have the below flow loss because of friction...

40 PSI with 25' of pipe = 65 gpm
40 PSI with 50' of pipe = 44 gpm
40 PSI with 100' of pipe = 31 gpm
40 PSI with 200' of pipe = 21 gpm
40 PSI with 400' of pipe = 14 gpm
40 PSI with 500' of pipe = 11 gpm

So what is wrong with this scenario?

1: You can't submit your pool equipment to that much pressure without blowing out something in the filtering equipment in short order.

2: Water always flows via the path of least resistance so with that, you will get little or no flow through the 1" pipe; all flow will want to pass off to the returns.

Solution is...

1: Use a separate pump.

2: Make 2 headers from 1 1/2" pipe with 4 - 1 1/2 by 1 tees on each header. One header will feed 4 sections of 500' of pipe each while the other header will accept the discharge from the 4 loops and return said heated water to the pool.

This will give you about 44 GPM or 2.640 GPH which means you will move all of the water in your pool in about 4.5 hours.

Questions are...

1: How much temperature rise will you get from a 500' coil of pipe at different flow rates?

2: Can a smaller pump at 20 PSI serve you better?

3: What about 10 PSI pump which will give you about 10 GPM flow if you use headers?

4: At 10 PSI we are back to looking at your existing 1 HP pump and with headers, it should work.

What would I do?

I would cut in a 1 1/2" tee as soon as it leaves the pump, install a FULL FLOW, double union ball valve and then a 1 1/2 inch FMIP adapter. You could do this with just a tee and a reducing coupling IF you leave enough pipe on top of the tee to later install an expensive valve IF you never run the filter in the evening. Obviously, running the filter in the eve will remove the heat from the pool exactly like a hydronic radiator hence the need for the valve. The valve will also allow repairs or additions to the pipe length while you are filtering.

Why are we going with a female iron pipe adapter? Because first off "I" would screw in a 1 1/2" male by 1" socket reducer, connect the first 500' of 1" pipe to it, fire off the pump and see what happens.

Caveat! Use no 1" ells!

You will also need to weigh if you really want to be running a 1 HP motor which is way over sized to begin with for your pool size but it is nicely sized for your filter.

This brings me back to looking at a smaller and separate pump to move the water through all that 1" pipe at minimal cost and stress to your equipment. Don't forget that the additional pump will have 5 to 15 pounds to work with on start up so with that, I am wondering how small a pump you could get away with if you decide on that route.

Changing your pump"s" to 220 volts is also a nice way to halve your electric usage.

Confused yet?

Please let me know how this goes, I am curious and love these types of piping ventures.

[Poconos]

I have a solar heater in my back field about 80' from the poolhouse and equipment. I ran a couple 1.25" pipes underground to it. Only a part of the flow goes through this heater. The flow is split 3 ways. Returns, a 4x20' mat heater, and the field. Both the mat and field dump into the deep end via hoses. Check this thread and let me know if the pic doesn't appear;

http://www.poolforum.com/pf2/showthread.php?t=943

The heater is 12 100' sections of black poly pipe layed out on black rolled roofing. The pic was taken while it was on tarpaper and I found that didn't last long. The roofing is a lot more rugged. Note the PVC manifolds. Running the pipes in parallel greatly decreases flow resistance. The pipes are held apart and in position by stiff wire wrapped around each pipe along the way and tied at top and bottom to steel rebar driven into the ground. I think I get about 20,000 BTU/Hr from the thing if my memory is right. I'd have to dig through my records but I remember a 4.5 deg F rise and 'I Think' something around 10 GPM or less. If I did the math rright those numbers work out to around 20K/Hr.
The only problem I've had with the rolled roofing are a few spots that have holes and the weeds want to grow through. Holes were punched in by Hooved Rodents (deer) that walked across it when it was snow covered. Seems to be holding up well and has been in place for maybe 4 years now.

I have a series of build pics that I can probable dig up showing how I fabricated this thing before hauling it to the field.
Al

[cleancloths]

Here is what I did. I ran a Tee with a valve off the line that feeds my returns, they have valves in-line down stream of this. I hooked up two 2' by 20' solar mats which I got on eBay for aout $175. I have an Intelliflow variable speed pump. During the day I valve out the returns and open this line and run the pump at about 1100 RPM. I get plenty of flow through the mats and the pump uses about 100 watts of power. At night I run the pump at a high flow rate through the main lines. This works double well since I have time of day power pricing and it much cheaper to run at night. I have a 20x40 IG pool and these two panels plus the solar cover are enough that the pool stays between 80-85 degrees except in April and Sept when I need to run my heat pump a little.

[jkoch]

WOW, Thanks for all the great response. The 1 hp with 2000 lbs filter I know is oversized but I paid 100 bucks for the Hayward filter and pump, pump being 2 years old. This is my first pool and with the 100 dollar system, the Intex pump and filter still sits in the box, thank goodness. Its just amazing how easy this pool is to maintain with the oversized filter. I just run the pump on a timer for fewer hours and time of day to help with energy cost.

Anywho, If i am understanding the information you kindly provided, I will need to buy a separate pump to do a solar heater as you described. Is that correct?

Thanks,
Jim

[waterbear]

Not necessarily. Much depends on how you build an plumb the collectors. Start by reseaching on the internet for DIY solar pool heaters and take it from there.

[mas985]

If you use a single line of 1" pipe, the head loss will likely be quite high and flow rates very low. However, if you use 10x100' lines in parallel instead of a single 1000' line, the equivalent head loss will be close to 100' of 2.5" line which is a much better situation. 20x50' line would be the equivalent of 50' of 3" line which would be even better.

Also, 1" line is probably going to be less efficient than using smaller tubes like many solar panels. 1000' of 1" line is only about 80 sq-ft of surface area so that is less than 20% surface area coverage for your pool which is a little on the low side. While it will probably add heat to the pool, don't expect too much of a rise.