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diy pool heater Answered

i have tried so many different ways to heat my pool water and have had little luck. One way I did it was to take about three hundred feet of black 1/2" drip line and run it around the pool rim. I supplied cold water from a smalloutlet attached to the return line,using the power of the filtration pump to move the water from the pool through thecoil and I adjusted the flow to about half of the normal, then at the end I had the heated water re-enter the pool. Iwould say the water got to about 100 degrees, by the time it went through the drip line. The problem is that it wasn'tefficient enough to have any real effect on the pool water temperature which stays at about 60-65 even on the hottest days. I live in the Sacramento area of California, and we get pretty hot summers, usually about 90-105.
Any suggestions on how I could make this idea more efficient? My pool water temp is always too cold to swim in, and I have a capacity of 12,000 gallons.



2 years ago

We just tried or better better tried to build a costfree pool heater for a friend of mine.
Only a small, round pool, approx 80cm heigh and 1.5m in diameter.
List of materials:
3 condensers from old friges/freezers, matched in size to the next part
3 old windows, still in the frame
1 coil of copper tubing, inside diameter to match outside diameter of the condenser coils
1 caravan water pump rated for continous use (12V)
1 small solar panel with controller to provide about twice the required power for the water pump
Some home made connectors to get the pump onto the copper coil - simple, flexible PVC tubing and cable ties ;)
Some old wooden panels or wet room rated plywood
Whatever is missing along the way, like nails, glue, screws...

General Idea:
Pool heating for free by utilizing solar power to both heat the water and pump it around.

How to:
The window frames are covered on one side with the plywood or panels.
We choose the "outside" as it only left a few mm of free space between glass, condenser and back panel.
Holes were drilled to connect the coils and window frames with each other.
For ease of later removal we included some quick connectors between them.
After placing them in a really sunny spot and connecting them with the PVC tubing we used the remaining copper tubing to make the connections to the pool and pump.
It is just easier to work with somthing solid if you want to keep in one place and prevent kinking along the way.
The solar panel was placed right next to the former windows and sonnected via a charge controller to the pump as the load.

Problems we found along the way that you could avoid:
We simply forgot to paint the inside of our window boxes black before putting the condensers in.
This meant we had to remove all the screws holding it as well as waiting another day for the paint to dry - thank god they were sliding windows...
Pressure and pump....
We decided on a caravan water pump or better a 12V water pump rated for continous use and with just 6mm pipe connectors.
Was advertised for caravan use when "high demand" is a priority.
You want the pump to be able to provide enough pressure so the water actually makes it through the thin pipes without loosing too much flow rate.
Without anything connected the pump made a nice 2.5m heigh fountain.
Connected to everything the fountain was only about 40cm heigh but still enough for a good flow.
Aquarium pumps are basically useless here as they are not designed to provide any proper water pressure, you would need much thicker piping and the pump from and external filter system for this to work.
Intake and outlet....
For obvious reasons you want to get the water in from the bottom of the pool as it will be coldest down there, especially if you don't have any insulation on the ground.
The same is true for the warm water coming back, but here we can simply place it near the outlet of the normal water filter pump.

How good does it work?
We filled the pool from the tap, so the water was quite cold.
Last year and in similar conditions but without the solar heating it took over a week for the water to warm up above 20°C.
The concrete underneath is certainly not helping...
Three days with good sun and the pool was at a nice 24°C - enough to disconnect the solar panel for a while as noone wanted a hot bath on a hot day LOL


6 years ago

Thanks a lot for this post. I was searching for this on the internet today, really glad!


6 years ago

Your description does not sound reasonable. I live south of Fresno so I have a very similiar climate to you. I have a 10,000 gallon above ground pool and it easilly gets above 80 degrees in the summer with no intentional heating effort on my part.

If your temp number is correct, I have two possibile reasons.

1... Is the pool in the shade?  If so, try opening the site up to more sun.  I once put a shade cover over my pool and that year the water stayed pretty chilly.

2... I will note that night-time temps in Sacramento rarely fall below 70 in the summer, so 65 degree water is below ambient temps.  This can only happen if "new" water (at about 50-55 degrees in your area) is being added regularly, and in large quantities.  How often is water added to the pool?  Does the pool have an undetected leak?  If it is an in-ground pool, it likely has an auto-fill valve and you may not even know it is adding water. 

Good luck. 


6 years ago

You have the right idea just make it bigger. You need more coils in parallel to had more heater to the pool. See below example of a good system.




7 years ago

Put a solar cover on your pool while you're not using it. It will
a) Increase heat gain on sunny days
b) Stop the heat gained through the drip line from escaping
c) Reduce evaporation.
d) Keep out bugs

The most important time to have it on is at night while you're not getting any heat gain from your piping. Also remember to turn off the pump that circulates water through the piping at night, or you'll be losing not gaining heat throught the piping at night.


7 years ago

I have seen the same system you are talking about, but instead of running around the outside of the pool, they ran it up the side of the house, and made "loops" from the top of the roof to the bottom. Didn't look bad either, really couldn't tell it was even there, and then ran it back down the house and into the pool.


7 years ago

What about putting a solar cover on the pool. This stuff looks like blue bubble wrap.


7 years ago

Search "solar pool heater" and you will see other ibles on this topic. Seems they all built a typical collector box aimed at the sun. Water is heated to a higher temp inside the windowbox and output to the pool. Maybe the heat is lost circulating around the pool rim to the outside air before it gets into the pool. Good luck.