Solar Pool Heater Problem

[Richard Fay]

I bought a home with a pool and a solar heating system with panels on my roof. There is a sensor that is supposed to open a valve and circulate through the solar system when the water on the roof is 5 (or 10 I forget) degrees warmer than the pool water. There is a light on the control to indicate if the sensor needs to be checked.

The check sensor light is not on but the sensor control seems not to be working. At night when the nothing is being circulated if I turn the control to off then the valve closes but then when I turn it to auto the valve opens even at night. It appears that the valve is always open (water circulates to the roof) unless I use the manual override and turn it to off.

The solar repair people are expensive.

Last year the check sensor light was on and the valve always open, just like now.

Some questions:
1. Can I just manually work the system, ie open the valve when it is sunny, close it when it is cloudy or when the circulating water appears to be cold?

2. Or just leave the valve open.

3. Any ideas as to why the check sensor light is not working but the valve control is also working.

Thanks