help with loud bangs from boiler and pipes

hello there

i have a potterton suprima 40 and just changed the pcb 3 day's ago with the upgrade kit because all it wanted to do was trip out. however since i changed the pcb it worked fine for 3 day's UNTIL loud bangs withe the boiler and pipes i when i opened the side door the red light was flashing. I reset the boiler and worked fine for a while then bang bang bang so i ran to the boiler and turned it off. now i am looking for help with this 1 many thanks for reading any ideas????

is the pump running

i did not check it before i turned the boiler off.
I have switched the pump up to level 3 instead of level 2 so far so good.