DIY solar heater question

[Gomez5693]

New plan. Since I already have some 150' of black garden hose on a spool, I'm going to replace to hose between the pump and pool with a new hose and will have a in-line manifold so I can simply hook up the garden hose and spread it out in the yard. I'll put a valve in the hose so I can control how much of the pump's flow is going throught the garden hose.
In my mind it works great, so we'll see when I get it put together.

[Gomez5693]

I got the parts and put the manifold together last night, allowed it to set up for 24 hours then put it in place today after work. Here is a pic of the manifold:

and 200' of black hose;

Unfortunately it's too late in the day to get enough sun to see how well it will work as a heater but I can easily control how much water is going through the hoses so hopefully I can do more testing tomorrow.

[mas985]

There are two very important aspects of solar heating that cannot be ignored.

#1 Heat gain is proportional to the surface area of the panels. 150' of 1/2" hose has the equivalent surface area of less than 10 sq-ft which is only about 5% of your pool area so you will end up with very little heat gain.

#2 Heat transfer efficiency is dependent on flow rate. The higher the flow rate, the more efficient the heat transfer (i.e. less heat is lost to the environment). If you try to force water through the small hose, you are going to severely restrict the pump and have very little flow rate through the hose so the efficiency is going to be very poor. Not to mention reduced filtering.

If you want to build a more effective solar panel, you need to use many parallel runs of hose to reduce the head loss like most purchased panels have, plus create a surface area that is at least half of the pool area. But you might find that buying a cheap panel on ebay is easier and cheaper.

[Gomez5693]

I understand what you're saying. My goal was to extend our season by a couple weeks as cheaply as possible for now. Next spring we'll move the pool to where it will get more sun and that will help keep temps up.
I currently have 200' of 5/8 hose and 150' of 3/4 hose attached, which I realize is still no where near the surface area you are talking about. The main section of the manifold is 1.25" so shouldn't cause much additional restriction when wide open. At half closed I can hear a difference in the pump, so I plan to stay just over that. Tomorrow I hope to measure how much flow is going through the garden hose and at what temperature it is coming out.

[mas985]

If you bypass most of the water around the hose, then the water coming out of the hose will likely be high due to the lower flow rates but that just means you are losing a lot of heat to the environment. The idea is to have high flow rates through the panel and have very little heat rise. This is what maximizes heat transfer and efficiency.