Yes seriously, they are not plug and play relays. I would set the temp where you want it and go from there. At some point it may start tripping the breaker or go into another error code. And yes the circ is designed to run 24/7 it's the temp sensor that controls when the heater comes off and on. As far as a consequence it should probably be fine till something else comes into play, if it reaches 112 or so the high limit will trip and shut the heater down.
I don't know if it will work or not, but you might try killing the power for 20 min or so, see if it resets itself.