Glow worm overheats and locks out

[TBeckett100]

I have a 4 year old Beatacom combi.

We went away for a week, came home and decided it to top up pressure. I may have over pressured it, but the heating worked all night.

Next morning there was no hot water and the boiler was flashing at 80 which is overheat. I bled a radiator to reduce pressure to 1.5 and reset the boiler however the heating works fine for about 15 mins then it lights 30 ( doesn't flash) then it flashes 80 and cuts out

If I switch the boiler to hot water, no issues bathing or showering.

Not really sure what to do. Have bled all radiators and water came straight out.

 

[dcawkwell]

Sounds like there isn't any flow going into the central heating.
Maybe the diverter valve has stuck in hot water position.

A blockage in the central heating is also possible.