Water temp surpasses set temp

AZAA

Silver Supporter
Apr 9, 2020
59
Gold Canyon AZ
Pool Size
5850
I have Heliocol solar system controlled by a Hayward Pro Logic unit. I have set my water temp max to 88 degrees. My pool temp, as displayed on the controller and verified by my floating thermometer, continually surpasses 92/94 degrees. I understand (I think) that it is the Hayward GVA-24 valve actuator that is supposed to restrict the amount of heated water reaching the pool. Now...where is the sensor that tells the valve to close? I have been told it is on the roof sensing the temperature of the roof! This sounds absurd. What does the temperature of the roof have to do with keeping my pool at the set temperature? I know how to manually rotate the GVA-24 valve to close or partially close it but I want to get it back to it working automatically again. Also...what position should the 3-way switch under the valve actuator be left at? Forward moves it one way, back moves it the other and center is neutral or off. A Hayward rep I talked to says if the switch is in the off position that it will not receive commands from the sensor to move. So do I leave it in the back or forward position? It seems like it would burn out the little motor if left it like that.
When this problem arose earlier this season there was a warning (?) on the read-out that said Solar Switch Open (or something like that). That only lasted a few days and for the last few months it has not appeared again.
So...where is the darn sensor, and which position should the actuator switch be in? I thank you all for putting up with this wordy question from a pool newbie and an even newbier forum member.
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
3,176
Morris Cnty NJ
Take a pic of the piping and the valve. Theres no right way. It depends on how it was installed and the valve orientation which way it should be set at. The sensor is on the roof and that talks to the prologic to actuate that valve. There is also a sensor in the water that plays into the mix. What does water temp on the display say does it match with pool thermometer.
 

AZAA

Silver Supporter
Apr 9, 2020
59
Gold Canyon AZ
Pool Size
5850
Thanks. The sensor in the water pipe seems to be working since it agrees pretty much with my in-pool floating thermometer. I was led astray I think by my pool guy who said to leave the 3-way switch in the middle (off) position when not moving it manually. Now I know that it will not respond to the PR commands when in the off position. I'm going to leave it "left" for a day and then "right" for a day to see if it responds to temperature commands. If it does not then I must assume it is the sensor. I still don't understand how a sensor measuring roof temperature should control my water temperature. Not looking forward to climbing up on a sloped Spanish tile roof to change the sensor.
 

jimmythegreek

TFP Expert
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In The Industry
Aug 10, 2017
3,176
Morris Cnty NJ
Simple really. The sensor checks ambient air temp in the direct sun. If its about 10 degrees higher than current pool temp AND the solar set point is higher than current pool temp it knows therea solar heat available. It opens the valve and starts warming the pool. They work well. If you pay attention a cloud batch will shut it down and then re open when they pass. When you have overheat issues its rarely the roof sensor. Usually 1 of 2 things. The water temp sensor is going bad or the wiring to it is damaged OR the actuator is getting stuck. The roof sensor just initiates the call for heat the prologic and the water temp sensor make the final call.
 

AZAA

Silver Supporter
Apr 9, 2020
59
Gold Canyon AZ
Pool Size
5850
Alright! An answer I can work with. I've been all over the internet, on the phone with Hayward and Heliocol people. No one could explain it like you just did. Thank you.
So...If the roof sensor detects 100 degrees and the pool temp is set to 88 degrees and the water is actually 80 degrees, the valve will open and allow heated water through.
If the roof is 100 degrees and the water is actually 94 degrees, the valve should close or perhaps partially close. (But if working properly the water should not have reached 94 in the first place).
I think I can rule out the actuator since it moves freely when manually rotated. And as I've said, since the water sensor closely agrees with my floating pool thermometer, it seems likely that the water sensor is not communicating properly with the actuator. If I've got that right, I'll take it from here. It's very good of you to have taken the time to explain this to an absolute newby. Thank you again.
 

Rocket J Squirrel

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Jun 7, 2018
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Alamo, CA
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You still need to set the little 3-position switch to one of the 2 "on" positions. You'll need to determine whether the solar should be engaged at the moment, and set the switch accordingly. After that, the actuator should control the valve properly on its own. It will not burn out the actuator motor.
 

AZAA

Silver Supporter
Apr 9, 2020
59
Gold Canyon AZ
Pool Size
5850
Thank you. Please verify: The word OFF should be over the pipe that is indeed off, the lever parallel with the OFF pipe. Those of us used to the position of a 90 degree valve would assume the actuator lever would be perpendicular to the pipe when off.
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
3,176
Morris Cnty NJ
Just so you know the valve never partially opens. There is either a call for heat or not, no in between. There is also a solar extend feature and other settings avail. You can pass your set pump run time and keep heating pool if all the parameters are met. I have seen boards act up and do wierd things. I would keep an eye on it and when the pool actually overheats next time go into diagnostics menu and record the actual readings the pro logic is seeing at that time. It can very well be bad communication to the valve actuator.