I notice in my Haynes manual for my 94 Astra 1.4 petrol 5 door hatch that the thermostat starts opening at 92 degrees Cel. and is fully open at 107 degrees. The cooling fan comes on at 100 degrees Cel. As I understand that the boiling point of water is 100 degrees Cel. under normal conditions, can anyone tell me what is the boiling point when the water is under pressure in the system. Thank you, Wilson.