Aqualink RS8 freeze protection problem

[agent-P]

I have an Aqualink RS8 controller with an air temp sensor that oscillates 3 to 5 degrees. When the air temperature gets near the freeze protection set point. It tends to cause the pump to turn on and off every second or two. I have replaced the sensor a couple of times to no effect.

I would love to hear if anyone has experienced this and found a simple fix. I am trying to decide whether to try to fix it or just gut it and replace the electronics with a Raspberry Pi. I am also interested in any other suggestions.

 

[PoolGate]

Where is the temp gauge located? It should be in a place that does not get direct sunlight. Also helps for it to be in still air. Mine is very consistent and meets all the previous criteria.

 

[agent-P]

Thanks for the suggestion. I already have it in the shade of the control box. I did some troubleshooting. The problem is somewhere in the controller circuit. The signal across the sensor is very stable. I now have a raspberry pi reading the rs-485 data bus. I have a software solution in mind. The full range of the freeze protection set point is bigger than the instability. So, I can mange the set point based on a real-time analysis of the temp instability, or I can just automatically turn the pump on when the low end of the instability gets within 1 degree of the lowest range of the set point. If that doesn’t work, I will just disconnect the Aqualink sensor, and connect a temp sensor directly to the raspberry pi GPIO, and have the pi mange the freeze protection directly. I will upload the solution with a link to the code on GitHub when it is complete.

Thanks again for the suggestion.

 

[lakeboater]

I have another active Aqualink freeze protection post, you may want to read. You can search on Lakeboater.