I have just (well almost) finished an installation using a Glow Worm,Flexicom 15hx boiler. I wired it all up today and when the boiler tried to fire up i had a bit of a surprise. There was a mini explosion inside the boiler and it then went to fault code F1. ??? maybe a gas problem the installation instructions tell me. So I checked all the gas and found no problem. I had purged the gas as normal before i started the boiler so it can’t be air. I reset the boiler and tried again. Same thing again but with slightly a bigger bang. Sounds like a backfire from a car. At this stage i though the boiler was going to fly off the wall so I turned all gas off and went though some checks again but to no avail. Fan runs, ignition sparks and all wiring is right. Checked inlet pressure on gas valve and this went from 0 to 20mb in about 30 seconds. Not straight up as usual. Disconnected valve on outlet side and gas flows freely. I’m stuck. Can anyone help? Never had this before with any boiler. First time using this boiler