My geyser is outside and continualy blows (overflows). It is set at 60°C
This chews up my electricity. How do I stop it doing this?

No wonder your water heater's tripping the overflow. You have it set way too high at 60c, (140f). The factory setting on a water heater's 49c,(120f) Reduce the temperature setting to 49c and see if that doesn't stop the blowoff. Good luck, tom