When my solar pool heater is off the pool started to heat on is own.

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S

sjungers

0
Jul 14, 2010
29
Huntington Beach ,Ca.
This just started to happen. With the conventional pool heater off and the solar heater off the pool temperature is rising much higher than normal. Today it rose to 83 degrees with the air temp at 75 degrees.The pool temp is normally always less than the air temperature with no heat in use. The only thing I can think of is that it might be a bad return check valve. Its a 2" Flo Inc. swing valve. I haven't removed it yet to inspect it yet.
The Hayward Valve Actuator and valve on the suction side appears to be working fine and I doubt water could be bypassing that when off. Any ideas?
 
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Yeah, sounds like a thermosiphon. If you have a union above the check, you could turn on your pool pump, crack the union, and see if you're getting back-flow.
 
Replaced the check valve. But no change. In addition to the solar acuator valve being in the off position I closed the manual valve just behind it to make sure the solar valve wasn't leaking.
I am at a loss to know why my pool is heating to 84 F degree with an air temp average
temperature about 77 F degrees without any detectable heat source . By the way,the Jandy pool temp sensor reading is correct. I checked it to be sure.
 
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If your pool is in direct sunlight, it’s possible that it’s heating that much just from solar gain. That IS a pretty significant gain though for that ambient temp. Is this the first year you’ve owned it?

Be sure to stick the old PVC check as a spare since it was determined to be good.
 
The pool is 27 years old. The pool solar is about 7 years old. I don't recall it ever gaining that much heat relative to the ambient air temperature. I wouldn't mind so much but it does require a higher percentage of SWG on-time. Yes, I will keep that $60 check valve as a spare since it appears to be good.
Thanks again for your replies. I will report back if I find something I've overlooked. It wouldn't be the first time. Ha.
 
No problem. Wasn’t much help! But, just make sure you’ve traced out your whole system and considered every flow path. With thermosiphoning, you can get reverse flows you wouldn’t expect.
 
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My pool is still heating on its own . Ambient air temp yesterday was 78F degrees and the pool water temp rose to 88F degrees after starting at 81 F and running for 5 hours.
A couple of things to note are:
1) With the solar valve off and the pump running, the return check appears to be closed looking through the NEW clear plastic check.There is a bit of an air gap at the top of the valve. So.... I don't see how the water in the return side could go up 2 stories after being checked.
2) With the suction side solar actuator closed ,in addition to the manual valve closed behind it, I don't see how the water could go up 2 stories.
3} Strangely ,the suction side 2 " pipe feels slightly warmer than the return side pipe. I used a IR laser temp tool to check..
4) When the solar valve is actuated on I do see a lot of air jumping up in the pool until all the air is out of the collectors. Which is normal. But it tells me that the water must have drained out sufficiently when the solar heater was turn off. And indeed I do see it rush back into the return check.

My other thought on this concerns a vacuum relief valve (If it has one). I cannot get a hold of my original installer to find out if there is one installed.. And it is difficult to see on my 2 story roof. Could this cause the water to stay in the collectors and flow back into the system when the pump is on? Or am I "barking up the wrong tree"?
This has been a "Twilight Zone" issue for me.
 

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Do you feel like this has sufficiently addressed your issue? Seems you may still have some passive heating? Perhaps you could post a few photos that clearly show the flow path and we can help think through any remaining issues?
 
I am still getting some passive heating that has got me in a quandary.Here are some shots of the flow path.
NOTE: The top check for the automated heater bypass was rendered unchecked(removed flap) as I found it to be superfluous.
Also keep in mind none of the equiptment has changed but the problem arose suddenly with in the last 30 days. Of course the checks were replaced subsequently.And the temp sensor recalibrated to less 3 F degrees. That brought the temp down to 82F with air temp at 76.Still to high in my mind.20220728_154533.jpg20220728_154659.jpg20220728_154521.jpg20220728_154501.jpg
 
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Is that a gas or heat pump heater I see in the photo? Are you absolutely certain that it’s not inadvertently in the on position with the thermostat set at 82?
 
It is a old Teledyne Laars heater. 30 years +. Works great. No it will not activate due to automated heater bypass. No water pressure present .In addition I added a flow switch in case the pressure switch failed in the heater.It was recommended here in the forum.
 
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