Definitely got some pressure loss happening. 🙁 Only a couple of seconds of the filling loop tap open to bring back up to pressure every few days / week. Only noticed it since having the heating back on this winter.
There doesn’t seem to be any discharge from the external vent so I think the PRV and expansion vessel (internal to Gloworm condensing boiler) are intact.
Can’t see any damp patches in ceilings or rad joints, so I’m thinking the likely culprit is an downstairs underfloor weeping joint. Some is plastic under suspended floor, the rest copper is under a screed. Has anyone had any joy with the sealing fluids?
Otherwise, even finding the leek is gong to be a right pita.