"legin" wrote in message
ups.com...

Andy Hall wrote:

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.

Sound advice. The boiler may have a thermocouple which is linked to the
overheat stat, hence when it overheats it cuts the pilot. The overheat
stat may have gone sensitive but is an important safety device. Are
there Trv's on all of the radiators so when the rooms are warm there is
no where for the heat to go? Is the pump failing and cannot get the
heat away from the boiler. A temporaray fix may be to turn the boiler
stat down so that the water temp is reduced and hopefully will not trip
the overheat stat. It may just keep you going until you can get an
engineer in.

Legin

thanks for the advice
The rest of the system, pump, valve, tank etc are all new
so its the boiler IMLO
The massive rumble when the boiler is hot, leads me to think its boiling the
water
but, llike you say, if the pumps working, the water should'nt stay in the
boiler long enough
for it to behave like that
No TVR's on the rads, but its been flushed 3 times this year so blockage
maybe not - no black sludge or anything
Thermostat ordered for next day delivery and Gas engineer coming tomorrow
when I ring him to let him know the parts arrived.
I might try lowering the dial on the thermostat to see if it behaves today
as suggested.
thanks again
--
Vass