On 24/07/2016 09:54, bm wrote:
"John Rumm" wrote in message
...
On 23/07/2016 21:07, bm wrote:

Any ideas guys?
8 years old prolly knackered?

Temperature control too high? (or flow rate obstructed?)

Fraid not, John.
I think I had this before, just inside warranty. Thermocouple maybe? God
knows which or where.
Looks like dipping into the pocket.


Open circuit connection to a NTC temperature sensor would be another
possibility - that could lead to the controller thinking the DHW
temperature is always low, and so working flat out to get it hotter.

I think I would start by checking all the plug connections in the wiring
loom close to the DHW plate exchanger, and possibly the main HE as well.
(I had a similar problem on a friends Vallant combi that I posted about
a short while ago - it was reporting an over temp fault on the main HE,
even when the boiler was first turned on an had not fired yet!)

If that does not fix it, then check the DHW temperature sensor itself
(just with a multimeter to start with - you should see its resistance
fall as the water gets hotter). I had one of those fail on a previous
Ideal Isar - I was able to get the boiler to function short term (it
locked out during startup diagnostics otherwise) by disconnecting the
cable from the sensor and sticking an appropriate value resistor in the
connector.

I also found after swapping out the sensor probe, that I could "mend"
the non working one, simply by gently bending the probe part a bit.

--
Cheers,

John.

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