chances are if the overheat stat is popping out there's a reason for it and that is because the boiler is over heating ! this is probably due to bad circulation so either the system is sludged up and neeeds cleaning or the pump in boiler is weak or both, the first thing to try is to add some strong cleaner to system like sentinal x400 or fernox etc and run boiler with this in the system for a while (or until boiler cuts out ! ) drain and then add sentinal x300 and leave that in there for a few days (at this point the boiler should keep running) drain and then add sentinal x100 inhibitor and leave this in there. the only other alternative is a power flush b ut these are expensive and dont always work and you wont find out till you've parted with £300/£500 so try the DIY method first and at least then you've only lost £40 ! ooh and dont forget to vent all air in between each operation....
mark the gay boiler man, November 2008
