My boiler hits high pressure as soon as it starts up and faults. Vokera ?

the expansion valve needs inflating as it a tank with a balloon in it as the cold water heats it expands causing the balloon to shrink if its deflated or leaking the pressure increase instead drain the central heating system leaving a valve open get to the top of the boiler unscrew the cap on the red tank and inflate it with a foot pump to 2 bars on the gauge if u need to keep doing on a regular basis its burst and will need replacing

kash
November 2010