Hi! I've been reading some threads in here and you all seem like a very helpful bunch so I was hoping you would be able to help a damsel in distress! I had problems with my boiler constantly tripping so I asked advice from a plumber and was told I should replace the 3 port valve, which I did (with help from my clever Dad!). Although this did solve the other problem I was having previously with the radiators heating up when just the hot water was on, the boiler only worked intermittently and cut out the rest of the time. We thought that the next logical problem was the pump, which had also been making some strange noises, so we fitted a new pump and (after lots of swearing and dripping pipes), the problem was actually worse! Now the boiler only fires and stays lit for a few minutes before the flame goes out and the little "overheat" button pops out. Both the valve and pump seem to be doing their jobs, because the valve changes position depending on whether you turn on the heating or the hot water and the first radiator in the system starts to warm up before the boiler trips. What is the next logical problem with the system? As far as I know it's a "glowworm" boiler. I don't know the technical name for the type of system but there is a hot water header tank and a central heating header tank and also a little valve near the tank that you can bleed with a radiator key! Can anyone help me with advice?