Worcester 240 problem

[Jiffy]

I have a Worcester 240 which trips on overtemperature a few seconds after I turn off the bath tap. This doesn't happen with say just a sink full of water or the shower.
It quite often makes an unpleasant noise when I shut off any hot water tap, depending on how long and at what rate it's been running at. Any suggestions?

 

[Knightrider]

Sounds like the heat exchanger is on its way out, have you noticed a drop in water pressure on the DHW side?

 

[DP]

Reduced flow at hot water tap would not cause the boiler to overheat- it would modulate to reduce flame size. If even this was too much, the burner would go out.

 

[Al Naz]

power flush required

 

[Jiffy]

Thanks guys, I haven't 'noticed' a drop in pressure knightrider, I'll try the flush first then I'll take it from there. A new Heat Exhanger sounds ominous and expensive maybe I should think of replacing the boiler when I get back home. Thanks again.