Hi I have some plumbing knowledge but I am not to hot when it comes to boilers. I have recently had to adjust pipe work for a radiator and drained down the system which is a sealed system in a valiant Eco tec plus not sure what model combi boiler which is no more than a few years old. The customer the next day rang me to say the pressure was at 3bar which I know is not the norm. I went back to sort it out and reduced the pressure which was very high and thought I would check to see if the filling loop was the problem. I disconnected the fill loop from the feed to the heating to discover water was passing when the water inlet valve was in the closed position. So I thought this was the problem, wrong this was only the start. I removed and checked the inlet valve to the central heating and hot water feed and thought I could see some wear so I got them to order a new one. I went to fit the part and discovered that it was the wrong part which was ordered but managed to cap off the inlet valve to stop any water leaking into the heating system and over pressurised the system. The New part arrives in a few days. While I was there they asked me to fit a towel rad in the downstairs bathroom so I thought yep no problems😊. I adjusted the pipe work which was a bit awkward and fit the rad, uncapped the inlet valve filling loop and pressurised the system to 1.5 bar and bleed the radiators . When I disconnect the loop which I know should be done to comply with the regulations I noticed water passing from the heating system valve, so now I have water leaking form the central heating valve and the cold water inlet valve when the loop is not attached. I have fitted quite a few rads in the past and have never had a problem like this. PLEASE HELP