boiler cuts out after 2 hours or so

[punjabi]

I have a Ferolli Sigma 20-40 conventional boiler.
If the heating is left to 'all day', or even on a timer, but with a long time
window, then the boiler runs fine for a couple of hours or so (and the rads
all get hot) but then it stops. This is problem at night when the house
becomes freezing in the early hours, and the boiler has to be manually switced to 'off', and then 'on' again - this keeps the boiler working for some time before it shuts off.

Any ideas? The room thermostats is set to maximum. The boiler is a bit noisy I must admit, so maybe the pump is a problem.

Many thanks in advance.

 

[crashndie]

am not a 100% on these boilers as i personaly think there pants, but from what your saying it could be the pcb thats why you have to switch the boiler off and on what sort of noise dose it make? is it fan flue or ballanced?

 

[clarkerothwell]

PUMP OVER RUN - Has the pump been wired to the boiler orto the control center?? Pump needs to run after boiler shuts down to stop over heating, had this problam with a relatives boiler.