worcester 24cdi overheat problem

[michael2]

IVE got a worcester 24cdi that was installed by british gas about six years ago it was placed in the origional cylinder cupboard and is on gravity feed from the header tank which is about 600mm above the boiler it has worked fine for the last few years but now it overheats and bangs and clatters when the hot water is run but the heating works fine. Ive checked the domestic hot water heat exchanger and that is not blocked also the diverter valve is functioning properly. Can anyone help as I have not come across this problem before

 

[stumpydick]

i have had the same fault on this boiler, the cause was scale or sludge in the plate h exchanger, causing overheating. found out after i had changed both sensors

 

[Gas2Air]

IVE got a worcester 24cdi that was installed by british gas about six years ago it was placed in the origional cylinder cupboard and is on gravity feed from the header tank which is about 600mm above the boiler it has worked fine for the last few years but now it overheats and bangs and clatters when the hot water is run but the heating works fine. Ive checked the domestic hot water heat exchanger and that is not blocked also the diverter valve is functioning properly. Can anyone help as I have not come across this problem before

And what checks are these?

 

[nickso]

check the primary heat exchanger on the left side above the pump or around the connection to the F+E tank. these are the places they always block up if they are open vented. primary h/e could be shagged if its bad enough.

 

[bengasman]

typical botch job, should have been converted to a sealed system.
your system is probably full of gunk now and needs cleaning