Solar Pool Heating System  (C) Daniel Friedman Solar Swimming Pool Heater FAQs
Solar Heater Troubleshooting Q&A

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Solar swimming pool heater troubleshooting Q&A:

Questions & answers about solar pool heaters: choosing, specifictaions, installation, diagnosis & repair.

This article series provides a guide to outdoor swimming pool heater choices, methods, design, installation & troubleshooting. We explain the diagnosis of a poorly-performing outdoor solar swimming pool heating system. Our page top photograph shows the 16 solar collector panels installed for a solar swimming pool heating system that was not working.

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Solar Swimming Pool Heater Questions & Answers

Swimming pool solar heating system piping details(C) Daniel Friedman

Questions & answers about solar pool heating system selection, installation, troubleshooting, repair, posted originally at SWIMMING POOL SOLAR HEAT, OUTDOOR DIAGNOSIS - topic home.

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Reader Question: how do I stop leaks in my solar pool heater from draining the pool itself?

I have a solar panel system installed below the pool elevation. I get leaks every so often and if I am not home, the pool will drain to nothing. Is there some way to prevent, stop, or turn off the solar to prevent from loosing all the water in my pool? - Tom 9/12/12


You should be able to put in a float switch that turns the solar off when the water gets low - James

Reader Question: using the home heating boiler to heat a swimming pool in Cape Breton?

I have read an article on your site about oil fired hot water heaters and found them very helpful. My question is, I have an above ground swimming pool and was wondering if I can heat it with an oil fired heater.The pool is 15x30 and52 inches deep. I live in Cape Breton, Nova Scotia where the summers are farily warm but I would like to extend the time I can use my pool. Any suggestions would be greatly appreciated. Thanks. F&D A, 1/13/2013


Oil fired heater (C) 2013 Daniel Friedman

A competent onsite inspection by an expert usually finds additional site specific information that might change the opinion we express here; That said, here are some things to consider:

Indeed oil or other fuel-fired heaters are often used as swimming pool heaters;

However because of the workload of heating the much larger volume of water in a swimming pool than is found in the hydronic heating pipes and radiators of a building, the duty cycle of the boiler will be enormously increased, as could be the corrosive effects of sending chlorinated swim pool water directly through a heating boiler.

Therefore if you simply tried routing your swim pool water through the heating boiler as an extra "zone" I think you'd find that the remaining life of your boiler would be short.

If fuel cost is not a concern, a different approach, one that kept the pool water physically separate from the water inside the heating boiler itself, might avoid the problem of boiler wear, tear, damage, & clogging.

Typical swim pool heater hookup (C) 2013 D Friedman

Watch out: if using any fuel-fired heater as a swimming pool heater, use either a "fireman switch" or a check valve on a vertical riser pipe to prevent back-flow of very hot water into the pool filter and valves from the the heating boiler when the boiler shuts down. Without this precaution the filter or valves may be damaged.

Also consider the effects of very hot water on plastic pipes used to conduct swimming pool water through the filter and pump circulating system.

PVC plastic piping cannot be connected directly to a heating appliance because of the dangers of burst piping and scalding burns. Typically codes require at least five feet of metal, usually copper, piping between the heating boiler and any plastic piping in the system.

Take a look at how indirect-fired water heaters work (INDIRECT FIRED WATER HEATERS) for an example of a different approach that uses the existing boiler but moves the heat transfer mechanism out of the boiler into a separate heating appliance through which one might try circulating pool water.

Then compare the installed cost and operating cost of using your existing heating boiler to heat the swimming pool with the installed and operating cost of installing a separate pool heater intended for that purpose. In making the comparison, don't forget to include among your considerations

On 2017-05-11 by (mod) re: recommendations for amount of solar heat capacity for a swimming pool heater

Solar swimming pool heater guidelines US DOE - original source at


Of course I wish you luck. And do let us know what you're told is what you learn may help other readers.

Watch out: placing solar pool heating panels on a vertical surfac, even with direct sun, may not provide as much heating capacity as you think;

usually the solar pool heating panels are placed flat or on an angled roof slope oriented towards the sun, as we illustrate in this drawing from the US Department of Energy.

In comparison with those orientations, for solar panels on a vertical surface the total solar gain will be reduced.

Here is a link to an article that includes photos of other rooftop solar heating systems that we have observed in Surprise Arizona: ENERGY SAVINGS MAXIMIZE RETURNS ON

Sizing Guidelines for a Solar Pool Heater

According to U.S. Department of Energy guidelines for solar pool heaters, the following factors must be considered when specifying the amount of solar heating capacity for your swimming pool:

The pool size (volume) where we add that the depth or ratio of surface area to volume is probably important as a factor in heat loss


Basically, the surface area of your solar collector should equal 50%–100% of the surface area of your pool. In cooler and cloudier areas, you may need to increase the ratio between the collector area and the pool surface area. Adding collector square footage also lengthens the swimming season.

For example, a 15-by-30-foot outdoor swimming pool in Florida typically requires a collector that equals 100% of the pool's square footage to accommodate year-round use. This equals 450 square feet of collectors.

In northern California, most people use outdoor pools 6–8 months per year, so they typically size their systems at 60%–70% of the pool's surface area. - source: "Solar Swimming Pool Heaters", U.S. DOE cited below.

The U.S. DOE solar pool heater guidelines document we cite and provide below includes simple formulas for calculating the BTU requirements for solar pool heaters as well as heating costs. Below we include some example specifications for solar pool heaters to help you assure that your design is likely to be functional.

Solar Pool Heater Technical Specifications

On 2017-05-11 by Robert

I will talk to a solar company tomorrow. from Phoenix, I can't stand looking at this beautiful cold pool any longer with a clear blue sky at 95 degree weather
Wish me luck

On 2017-05-11 by (mod) re: solar pool heating specifications

Thank you for the question Robert.

Solar panel technology has continued to improve since I put together the article on this page.

I still think that most likely you will need a fairly large area of solar gain, more than 2 panels, for a conventional pool solar heating system. All of the systems I've seen in Surprise AS used panel areas larger than what you describe.

I'll do some further research as perhaps will you to see what the capacity rating numbers are for the panels now on the market for swimming pools.

On 2017-05-10 by Robert May 2017

I live near Surprise Az. I just had a senior's pool installed by Shasta Pools Looks nice. I have sun on my pool 80% of the day, the avg. temp. has been from 80 deg to 100 degrees from the time we first filled the pool two months ago. The highest temp of the water has been 70 degrees our evening temp falls to 58 degrees avg.
the pool is in ground 8,671 gal. 5.5 feet deep 15'by maybe 18'give or take a foot.

It would cost an arm and a leg to pipe in a 1 1/2 " gas line from the meter and the heater installed, so I'm looking at a solar panel along the 8 foot tall wall next to the pool area this wall is 70 feet long this wall gets full sun from 0700 to about 1500 I checked a thermometer next to the wall at 0730 and it read 95 degrees.already
So i would like to install two double panels 4' x 8' side by side along with a pool cover at night,

My question is would this maintain an 80 degree temp.

would the pump draw to much electricity here in Az where the day time elec. is painful to look at.
Thanks Robert

On 2016-10-10 by (mod) re: solar pool heater leaks

Susan, what you describe sounds to me like a leak from a solar heater that was not drained.

On 2016-10-09 by Susan S

Our solar pool heater wasnt turned on at all this year due to unusual heat, so the panels should have been empty. However, they have started dripping at a rate of one drop per second fairly steadily in the evening when the weather cools. Is this normal condensation? We confirmed the isolation valves are off and there has been no rain for months. It's really weird.

On 2016-06-18 15:15:42.678087 by lori

degree The sun is starting to come out today, has been cloudy. Pool temp is 78 degree. Weather is supposed to warm up and skies clear. and by 1:00 ot wo;; be 82 degree.
can we turn solar on when clouds clear or when sun is directly on panels

Reader comment: I have no idea if our solar panel is working

(Feb 22, 2013) phillip said:
I have solar panel in the house I moved in but I have no idea if they are actually working. I think I have them on but the temperature in the pool still says 69 degrees and my weather temperature is 86 throughout the day. I cant get for my pool to warm up no matter what.

What is going on, please help. Because of that we only use our or pool 2-3 months out of the year and thats cause I live in sw florida!! Can you believe that.


In a case such as you describe the problem could be as simple as not knowing how to turn on the solar system or there could be pump, control, or panel repairs needed. I really can't guess from just your e-text. You'll want an on-site solar repair company to check the pumps, controls, and piping.

Question: gurgling pipes when solar system turned off

(Mar 30, 2013) Anonymous said:
The problem I have is two fold, Firstly I have a problem with my Solar panels draining when the pumps turn off. It is a gradual process and I can hear a faint gurgle in the pipes on the roof but the roof panels and pips substantially drain over night. I think it happens through a siphon process. The second problem I have is on solar pump start up it gets a lot of air in the solar pump and partly pumps air (a lot of it) until it overcomes the air and pumps only water. It sounds like there is a stampede on my roof at solar start up

My set up is This
My pump house is below pool level
My main pool pump is 1HP ans starts before the solar pump and when it is running without the solar pumping going it runs normally all the tile with no air in the system
There is a tee branch take off from the 40mm (1.1/2) pipe after the filter to a non return valve and then the Solar 1HP pump, Then there is another non return valve and the water is piped to the roof.

The solar panels are set up with the supply water supplied to the bottom left corner of each panel and the piping is balanced. The water goes through the panels and exits the panel at the top right corner of each panel until the water has traveled through all the panels and finally exits at the highest point in the top right corner and the water is returned to the pumphouse through a slightly larger pipe 50mm /2 inch a drop of about 6m/20 feet.

The pipe is connected back into the pool return pipe with a reducing Tee reducing the 50mm / 2 inch pipe on the branch to the 40mm 1.1/2 inch main return pipe. The distance between The take off for the solar and the return solar pipe is about 800mm / 30inches and there is a rise between these 2 points of about 10mm / 4inches

To recap, when the solar pump stops there is some draining of the panels both when the main pumps is also stopped and when the main pump is running. When the solar pumps starts there is a lot of air in the non return value sight glass and sometimes it surges pumping slmost only air and water


Check for a leaky check valve on the vertical piping system in and out of the rooftop panels.

Question: trouble priming the solar pool pump

(Sept 8, 2014) Rex Marshall. Port Broughton said:

I am new to the park and am having trouble priming a repaired pump. We have the solar strips on our amenities block roof. We have tried numerous ways to get some water into the system.



See these pump priming options starting at


since those procedures should work for you with a solar system pump too


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