We have a Biasi M90 24S which is intermittently locking up. The operation lamp blinks at twice the normal speed and the fan continues to run. The lock out lamp stays off though and the reset button does nothing. A power cycle is needed to start the boiler up again. Sometimes it happens every few hours, sometimes it can run for days.
It seems random and not linked to DHW or CH operation. We have a Tado thermostat fitted.
What has been done so far:
Diverter valve serviced (Leaking)
Pressure vessel replaced (Leaking)
Actuator replaced (It broke when being removed)
Temperature probes checked
Flow sensor checked
Pump checked
Fan checked
Venturi device checked
Air switch replaced (Pain to get to apparently)
Overheat cut out switch replaced (Pain to get to)
Ignition electrodes cleaned
Frustratingly the fault still remains!!
Any thoughts before we chuck money at getting a new circuit board fitted? It was working fine before.
The only thing I can think of is that the circuit board isn't modulating the gas properly and it is leading to the occasional overheat? Or maybe the gas valve needs to be replaced.
Biasi M90 24S locking up.
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