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? Various bits have been
replaced but to no avail. Very occasionally the system works.
Hard water area?
Is the heat exchanger scaled up?
Is there a blockage in the system
Is the pump working properly ?
I'm afraid, to properly diagnose this, more info is needed
is it fully firing up or just starting - still sparking?
Has this suddenly happened or has it been getting progressively worse?
Thanks for the reply.
It is a soft water area. Very unlikely the heat exchanger is scaled
up, as it is only 2-3 years old.
No blockage in the system since it has been known to work.
Pump seems ok, when the system works.
It seems to be more or less constant now, from an intermittent fault.
Apparently the gas engineer is now going to replace the heat
exchanger. Its a friend of mine, but it seems to be a case of just
trying things. I'm not a gas engineer, 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, 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.
I'm getting near to the stage to say get a brand new unit.>
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
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
=================If this was a carburettor in a car I would say that there was a bit of loose
grit periodically blocking the main jet. Your problem might be similar - a
bit of loose grit or scale might be blocking the the main jet / injector.
Have you tried removing and cleaning the main injector / burner?
Is the high gas coming on blowing the flame out?
Is the high gas coming on blowing the flame away from the flame sense
Dicky relay on the control board ?
You don't say what bits have been replaced
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