In message , obclare
writes
raden wrote in message
...
In message , obclare
writes
I have a problem with an Ariston a/23 combi boiler that has beaten
British gas and a handful of gas engineers.
The system fires up and immediately fires down again and fires up
again immediately and so on. Anybody any ideas?


....

, but I wondered if the
thermostat that tells the temperature of the heat exchanger could have
gone, so it thinks its hot and cuts off
,
That was going to be my next question after eliminating the obvious
ones. IF the temp sensor has gone off, then it could be still working in
a borderline fashion, but then you'd need to be able to measure the
resistance (IIRC about 10k at 20 degrees, about 3k when it's up to
temperature

but then there would have to
be another thermostat that tells it to fire up again. It does fully
fire up, as far as I can see. I don't know whether the spark stops.

Well, you know the little click, click, click, woom (so to speak) you
hear as the boiler ignites, well if it keeps on going click, click,
click ... click, click then it's not sensing the pilot being alight and
will stop and try again (I think ... I can't remember on the Ariston
exactly)


I'm getting near to the stage to say get a brand new unit.



Various bits have been
replaced but to no avail. Very occasionally the system works.

--
geoff