Hi, I have a similar problem with my boiler, pressure is always in red even when filling loop closed. I managed to take waterout via pressure relief to 1.5bar. Within 30min the pressure had gone back up within the red area. I was just wondering what was the outcome of the problem listed by nigelad. Thank you. Any advice will be welcome. P.S at what pressure does PRV open? And why doesnt it open if my boiler is alaways in red.