I have read most of the faults mentioned in this forum and my isar fault is linked, I think. We get the system working hot water & and radiators for a couple of hours but then you ear a noise (air) in the boiler, the pressure gauge moves up and down - the water coming through then gets very hot compared to as it was - then the fault condition comes in. I have flushed the boiler, bled any air out, the pump is working. It always happens have this rush of possible air and knocking noise plus this sudden increase in water temperature. I know the temp increases because I placed my finger on the pipework and felt the sudden change as the noise (blockage) went through. This was only for a couple of seconds. I am baffled because if it was blocked I would have had some evidence when I removed the motor & pump. I have also checked the small heat exchanger just following the pump.
isar boiler fault L9 plus three horizontal lines
- Thread starter Willibob
- Start date
How high does the pressure gauge go? It sounds like it could be over pressurising, discharging the excess pressure and the PRV staying open long enough to take the pressure too low leading to an overheat. If the pressure is rising above 3 bar check the pressure in the expansion vessel.
The mighty reds Still got more an we have been crap for 15years.
the pressure is only set to 1.5 bar.
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what would cause the pump to slow down?
the system was initially too high and you could hear the safety valve blowing off, and it states this would happen at 3 bar.
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