Can anyone help me with this fault?
Worcester 28cdi - it started with a seized fan.
I replaced the fan and the silicone hoses which were cracked. All good or so I thought.
A week went by and "Fail point J - flashing hot tap light" - occured, which is an air pressure fault.
I found some condensation in the silicone tubes and cleaned them out - All good.
3 days later had the same fault again so I checked the air pressure switch and ended up replacing it.
A week has gone by and it has failed again - it resets itself and the boiler runs as normal for a while - Worcester were unable to explain it after going through the full diagnosis and fault finding with me on the phone.
I remember that once on a council contract the same thing happened on a 25cdi xtra - they replaced the flue, fan, air pressure switch, PCB and ended up replacing the boiler cos they still couldn't fix it. The only way it would run was to leave the negative tube off the APS.
Another call to Worcester I was told that the thermistors may be faulty and the heat exchanger fins might need cleaning. I think he got the wrong end of the stick as the fault is always " Fail point J" - Air pressure fault and not lock out overheat.
The flue is clear, Fan/ Air pressure switch is new. Can anyone point me in the right direction?