I've had a problem with my boiler very slowly losing pressure, around 0.1-0.2 Barr per week. We have had BG out 5 times and they have replaced a seal and the EV but it's still happening. Looked for any obvious leak around the house and there aren't any. Next step to isolate boiler and see if it holds on its own, BUT... I've just noticed a join in what I think is our cold water supply pipe (photo attached) is weeping very very slowly......would this have any affect on boiler pressure or am I being wrongly hopeful?!
