I have a complete mystery here. Hoping for some words of wisdom!
I have recently had a new kitchen installed. An extra radiator was added at the same time onto some pre-existing capped pipes which were discovered when the kitchen units were taken out. (Plan A had been to run pipes overground from another radiator in the kitchen).
As soon as the radiator was added, the boiler pressure started falling (from 1.5 to 0 in half a day). At first, our kitchen fitter thought that he had not repressurised the boiler correctly. But after 6 visits from British Gas engineers (which involved putting sealer into the system, tightening radiator valves, and reseating the PRV), the conclusion was that by adding the radiator, a leak under the (concrete) floor on the old pipe work had been reactivated.
So that the new kitchen floor didn't have to be dug up. We had floorboards in the hallway taken up so that the pipes to this radiator could be located and capped. This was 4 days ago and amazingly the pressure has held at around the 1.0 mark. The mystery is that the 'offending' radiator still works!
I suppose my main question is whether it wasn't the capping of the pipes that solved the problem -but whether the problem was with the repressurisation of the boiler. The last engineer to carry out work was the only person (apart from the kitchen fitter) to drain down the boiler before carrying out any work. Or is it possible that by adding a new radiator a leak can be created on a pipe which it isn't even connected to?
None of this makes any sense to me, and although I'm pleased that the problem seems to have been fixed, if it started up again, then there would be no logical next step. I'm due to have a baby in the next couple of weeks and am desparate to get this sorted ASAP!!!
Thanks for looking!