A better solution is a closed loop system. A surplus collection of cooling components was used and a hand wired board based around a Teensy 3.2 single board computer module.
The Teensy board allows for touch sense inputs. The mounting screws near the bottom of the image are actually used as button inputs, using the Teensy board touch inputs, to control functions like switching to Celsius or Fahrenheit display. If the liquid temperature rises 5C over the starting temperature, the radiator fan turns on.
The pump on the left is 24V, The fan is 12V and the logic is 5V. A triple output power supply is at the very top.
The large red LED lights to warn of error conditions. The flow sensor, lit with the blue LEDs at the bottom must turn at a minimal rate, and the temperature, attached to the radiator must be below a set temperature. If conditions are not met, the LED starts flashing to warn the operator.
If you have a need for a similar platform, feel free to Contact us about your needs.