We have a Worcester 24 CDi. The pressure keeps going up until it reaches a maximum (3.5) and discharges through the overflow pipe. We have had boiler engineers look at the problem. They have replaced the heat exchanger twice but the pressure problem keeps reoccuring. The pressure increases if the heating is on or not. We now have problems getting hot water. The boiler is about 8-10 years old - is it time to get a new one? The water pressure in our house is quite high - is this the cause of the problem. We are worried that it would it affect a new boiler.