Glow worm Flexicom HX15

Hi guys,

First off I'm a qualified plumber,so have an idea what I'm doing lol

Had to drain down my heating system today as I had a leaking valve which was leading (I thought) to an F22 error code,

System is retro fitted with an expansion vessel but its still tank fed,as it was a boiler upgrade done on behalf of the local Co Council,

Anyway fixed leak,filled back up and still getting F22 but also an F11 now,water pressure is .4bar,but its always been that and did work fine for along time,which is why I thought the leak was the problem,

So boiler runs but wont fire most times,if it does attempt to then it will usually give the F22 error,if I then reset the boiler it will run,not fire until it eventually gives the F11 error,

Temp reading is between 44-55 degrees even though boiler has not fired since this morning?

Any ideas,

Cheers