On 2006-12-27 10:28:33 +0000, "Vass" said:

"Andy Hall" wrote in message ...
On 2006-12-27 09:30:31 +0000, "Vass" said:


The thermocouple to which you refer is a flame failure device designed
to turn off the gas in the event
of the pilot failing to light or remain alight.

If the boiler is overheating, the reason for that needs to be investigated.

The thermostat turns off the main burner when the water is hot enough,
but shouldn't turn off the pilot.

It would be safer (and legal) to call in a heating engineer to fix it.


ok so the probe is connected to the thermostat
so what is causing the boiler to overheat if the thermostat is working
correctly?
this makes no sense
--
Vass

It can make a great deal of sense.

For example:

- The pump may be broken or on its way out

- There could be a partial blockage in the heat exchanger or elsewhere
in the system.

If the temperature rises quickly enough, the overheat sensing can trip.

However - back to the original point of it cutting off the pilot.

Either way, if the OP is not sure about what he is doing, he should
seek the help of a professional.

The problem may only be the thermostat, but other things should be
checked as well.