DIY Solar Pool Heater

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Introduction: DIY Solar Pool Heater

Last year my Wife and I bought an above ground pool for exercise and recreation. We discovered that my Home shadows the pool in the afternoon, and that drives the water temperature down several degrees in the Spring and Fall. Since we usually don't get into the pool on Weekdays until after work, this made for some pretty chilly swims, even when the air temperature was in the 80's. I decided that a Solar heater that I could mount outside the shadow of the house would be just the thing to bring the water temperature up to more bearable levels.

Step 1: The Solar Collector:

I took a 4x4 piece of plywood and painted it black. Then I took 200' of 1/2" vinyl irrigation hose and coiled it tightly on the plywood, using UV-resistant zip-ties to secure the hose every foot or so by drilling holes and looping the zip-tie around the hose and through the plywood. As you can see 200' doesn't completely cover the plywood, but since I was following the square edges instead of using a circular coil I ran into a problem where the hose started to kink in the corners. If you look closely at the picture you can see I still have a few kinks to literally work out.

All done, and in the Sun, I took a temperature reading of the surface of the board at about 3:00 PM. The surface read about 134 degrees F.

Now we've got to get that lovely heat into the pool.

Step 2: Valve Assembly:

I put together a series of valves and "Y" adapters to route the water into the heater and then back to the pool, using the natural flow and pressure of the existing pool filter pump, instead of a separate pump. The 1/2" ball valves allow me to shut off the water to and from the solar heater and remove it once the afternoon temperatures make it unnecessary.

Step 3: Water to the Solar Heater:

The top is a smooth 1 1/2" "Y" adapter with a 1 1/2 to 1/2" threaded adapter in one side with a 1/2" male to male threaded nipple to a 1/2" ball valve and a 1/2" threaded to ribbed adapter that the vinyl hose slides on. I used two hose clamps on each hose fitting to avoid leaks. Sand all smooth surfaces prior to gluing to assure a good seal. IMPORTANT: Do NOT glue any threaded parts. The glue will set long before you get the threads tight. Use Plumbers Grease or Pipe Dope to seal the threads. Even Teflon tape may leak due to the high pressure.

Step 4: Regulator Valve:

The middle valve is a smooth 1 1/2" ball valve glued to a short piece of 1 1/2" PVC on both sides. By partially closing this valve the pressure will divert some water out of the top "Y" adapter to the solar heater panel.

Step 5: The Return Valve:

The bottom of the assembly is pretty much a mirror image of the top. A ribbed to 1/2' threaded adapter to a 1/2' threaded ball valve, to a threaded 1/2" to 1/2" nipple, to a 1 1/2" smooth adapter, to a smooth 1 1/2" "Y".

The flow of the water down the 1 1/2" PVC pipe through the 1 1/2" ball valve will draw the water from the solar heater into the water that flows into the pool.

Step 6: Timer:

If the water were allowed to constantly flow through the solar heater, the hundreds of gallons of cold water in the pool would overwhelm the 10 or so gallons of water in the solar heater. It simply wouldn't have enough time to heat up before it got sent to the pool. To solve this I installed an outdoor timer to my pool pump. The pump still runs several hours a day to filter the pool, but from Noon until about 6:00 PM the timer turns the pump on and off at 1/2 hour intervals. This gives the water in the solar heater time to heat up before it goes into the pool.

Step 7: Hot Water:

As you can see, the water flowing into the pool when the heater is operating is about 99 degrees F. This keeps the entire pool at about 84-86 degrees in the shade. Everything was purchased at Home Depot and cost about $50.

Now my Wife and I can get into the pool with an "Ahhhhh" instead of an "OOOOOOoooo".

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Runner Up in the
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2 People Made This Project!

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72 Discussions

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pcreson
pcreson

Question 3 months ago

Is this connected to the return port on the pool?
Could post more pictures of the connections at the pool and filter/pump?

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bnaivar
bnaivar

Answer 3 months ago

It is connected between the pool skimmer and the return to the pool. Remember to partially close the center valve to send water through the heater.

IMG_20200527_075500.jpgIMG_20200527_075451.jpgIMG_20200527_075525.jpgIMG_20200527_075429.jpg
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pcreson
pcreson

Reply 3 months ago

Thank you so much commenting back. Just to confirm the water heater system connections are only connected the return line system?

Capture.PNG
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bnaivar
bnaivar

Reply 3 months ago

Yes, I didn't want the hot water running through the sand filter.

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bnaivar
bnaivar

Reply 5 years ago on Introduction

A good question. Since it is actually irrigation hose, and not meant for above ground use, I really couldn't say. There might be some UV issues since the heater is meant to be pointed at the Sun. I had it disconnected (and in the shade) during the hottest part of the Summer, but I reconnected it last week.

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CeeKay123
CeeKay123

Reply 4 months ago

Landscape irrigation pipe is uv resistant, READ the Spec's in the product information online with most every retailer at point of purchase.

0
bnaivar
bnaivar

Reply 3 months ago

I bought a coil of tubing with a price tag o it. No specs.

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indysilverwing
indysilverwing

Reply 4 years ago

Maybe try painting over the hose for UV protection? Just a large can of black spray paint might help with the UV breaking down plastic.

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millmore
millmore

5 years ago on Step 7

I'd be interested to know what happened if you didn't turn the water on and off. I think it's actually making things worse for you. Heat loss is proportional to temperature, so if you heat the water in the collector to 99F, more is going to radiate away than if you heated it to 90F for example. It should be much more efficient to keep the water flowing through the solar collector all the time, and raise it by a tiny amount as it passes through than it is to have it stop,heat,go,stop,heat,go. Heating 1000 gallons by 1F has the same effect as heating 100 gallons by 10F and mixing it in, but you get less heat loss in the system with the 1F rise. That's how air source heat pumps work on pools - little and often.

Although, if you are achieving the desired effect anyway, who cares?

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CeeKay123
CeeKay123

Reply 4 months ago

right. and worse yet is the cost of starting that pump. typical for the electric use on start up is typical to 5 x the operating consumption -- not to mention using a pool pump like this would be rather expensive to replace from burn out.

For any pool you should know the gpm of the pump and number of gallons in the pool, you only need to change the water one time through the filter every 24 hours. An auxiliary pump is best to keep the life of the pool pump and cost of electric down...

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CecilC1
CecilC1

Reply 5 years ago on Introduction

that is why sizing the system is important. improvements on this design would be to use a small 12 dc variable speed pump ran off a pv panel size the system just big enough to heat the pool up on the coldest summer day. build a controller to slow down and speed up the pump as needed. add some check valves.

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StephWesto
StephWesto

Question 2 years ago on Step 7

I was wondering.. i have trouble finding the plumbing like this... where did you got it?? thanks!! nice project BTW

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CeeKay123
CeeKay123

Answer 4 months ago

pvc fittings are located at any plumbing supply house, you might be able to get everythign at the box stores, but likely not find it without help.

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bnaivar
bnaivar

3 years ago

I might have to look into something like that. Since my system is connected to the pool's plumbing, it causes the system to use too much chlorine.

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andrefierens
andrefierens

3 years ago

Genius ! Great Job !

Garden Hose as collector : I made a Portable Solar Pool Heater 1,04 k Watt DIY, first I used a garden hose, now a Intex Solar mat. So the module is Foldable and Portable. No need of electricity ! No sun, or clouds: the pumps stops.

https://www.instructables.com/id/Portable-Solar-Po...

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bnaivar
bnaivar

4 years ago

I have discovered a drawback to my design. Because I am turning the pool pump on and off more frequently that I would without the heater, my automated chlorine infuser is putting too much chlorine in the pool. Now that is Summer, and I don't need the heater, I need to reset the timer.

1
ArnaudM21
ArnaudM21

4 years ago

Your collector seems to warm (130°F), you lose a part of collected energy before it goes back to your pool. A solution could be to augment water flowrate. It is a common mistake to want hot water at the output. Look at this chart:

https://coropool.wordpress.com/2016/07/11/understandind-solar-efficiency-and-loses/

0
electric_piano_5k
electric_piano_5k

5 years ago

I wonder if by turning off the pump you are allowing the water to separate into a warm layer on top and colder water underneath. So it geels warmer to get in and the thermometer reads a higher temperature but overall the water is not warmer.

The guideline for solar pool heaters is you need panels at least half the area of the pool surface to be effective. So I think you need to make about 10 more collectors to make a real difference to the pool temperature.