Boiler fires up when i bang the PCB box

[andywade2002gy]

right so my boiler will start if i bang the box with the PCB inside, i've taken the cover off and checked the connections but cant seem to find anything loose.. i've also used a can of pressured air to clean the inside out.. still no joy but comes on for around 5 minutes if i bang it.

noticed last night also that the left handside pipe that goes from the boiler back up into the header tank was boiling and was sending boiling water and lots of steam back into the tank?

i have what looks like an air vent pipe thing (sorry i dont know what it is) above the right hand side pipe on the boiler up in the loft.. i believe this has been blocked before and wondered whether this was a problem as i drained the system yesterday.. arrhhh! i presume the 'overflow' lefthandside pipe out of the boiler should not get hot after 5 minutes of the boiler working?

 

[Mark Br]

Is it a Potterton Prima/profile?

 

[Agile]

Is the pump working and not airlocked?

All this draining causes air problemsand is never a DIY fix for any problem.

Tony