Situation: our temperature controller for our solar heated swimming pool isn't working, and it's a real pain to manually switch the valve back and forth to maintain a nice temperature. Pool guy says it'll cost $600 to fix. I say, it's a temperature sensor, a valve actuator signal and a setpoint, why can't I do it myself?
I assume the temperature sensor is some sort of resistive device, I can figure that out. What about the valve? It switches from input A to input B either by manual switch or from the controller. Is there a standard for these things? Just trying to collect some data before I dive in (hmmm...).