First place to try would be the circulating pump. 90% of the time Overheat faults are where the boiler is not dispersing the heat quick enough. A blocked heat exchanger is a more drastic fault and highly unlikely due to the age of the boiler. There may also be a thermostat or board fault but these will need to be pinpointed and fixed by a Heating engineer.
Steve
July 2008
Automatic Answer
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