Yeah i have the PID but i needed the pressure as an input variable to the PID
Discussion
well, the temperature and pressure are more or less the same given an excess of water, a la boyle's law, you can just use a temperature sensor and calibrate off it, the only time the pressure is gonna go down is if you run out of water and if you run out of water the temperature will probably drop quite dramatically
yes, a little laggy but it would work, you can tune the PID to compensate for that lag with the P and I factors