The pressure dial was usually between 1 and 2 (1.5) the pressure is now on 3 and 4 when heating is put on. The red light has being flashing every few seconds which i keep having to reset to stop it flashing.
Any suggestion how i can solve this problem to get the boiler working back to normal, been dealing with this for 3 days now, only firing up the boiler by putting the thermistate on constant to heat the house for a couple of hours.

sean, December 2009

System pressure can be lowered by either opening the drain cock on the system or opening an air vent on a radiator and catching the water.
This should be done with the boiler off and when the heating has not been on (cold). The pressure should ideally be at 1.3Bar when the the system is cold. Does the pressure go up only when you use the heating? if so you have a problem with the boiler. You should then call in a Gas Safe registered Engineer to find the fault.
If the pressure goes up even when the heating is off and you have a filling loop with a braded hose, disconnect the branded hose to check the filling valve is not passing water. If it is passing then a new fill valve is required. If when this is disconeccted is pressure still goes up when the heating is not on the main heat exchanger may well be pin holed. Rare but I have had one or two.

Anygasman, December 2009