My vokera linea HE faults as soon as it starts up whether it is for heating or hot water. I can see the pressure increasing before it faults on code 74. However if I switch it on and bleed the pump I can get the boiler to run. I then have to leave the boiler on so that the pump is on continuously and I have no problems. CH or HW (I just adjust the internal central heating water temperature as required). Any ideas?

Alasdair, November 2010

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