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Worcester 24 CDi RSF no hot water (HW)

Discussion in 'Plumbing and Central Heating' started by milgo123, 22 Apr 2020.

  1. milgo123


    22 Apr 2020
    Thanks Received:
    United Kingdom
    I just wanted to post my recent experience with my Worcester 24 CDi RSF that had developed a fault of no hot water (HW) and what was done to fix the issue as it may be helpful to someone else in the future.

    So suddenly no hot water (HW) but the central heating (CH) was working okay. Everything had been working fine until this point. There were no flashing lights on the boiler to indicate what the fault might be. Reading earlier posts on this forum I was able to check that the diverter valve pin was operating the microswitch when demand for HW was made.

    Approximately 3 days later without any intervention, the HW started working again. This lasted a week before the problem returned.

    Visit from an engineer to diagnose the fault (the boiler is covered by a maintenance agreement) The engineer advised me that he believed that the plate to plate heat exchanger was blocked likely due to sludge deposits and this was the cause of the problem. He could not fix the problem as the agreement has exclusions for any faults caused by sludge.

    Approximately 3 days later again without any intervention, the HW started working again. This lasted about 3 days before the fault returned. This time though there was a light indicator on the boiler of a fault. The CH light would flash 5 x per second when any demand for HW was made. This condition could only be cleared by switching the boiler off and back on again, the reset button would not clear the fault light.

    So in order to get the fault resolved, I ordered a new plate to plate exchanger (87161429000) and diverter valve (87161567460) and had them fitted. Repair completed and the fault remained the same. Note. the heat exchanger was NOT blocked and the water drained off from the system was clean.

    Further reading on the internet led me to want to check the status of the thermistor sensor which sits just behind the heat exchanger with a multimeter, as I attempted to do this it literally fell apart in front of me! So off to the local merchant after ordering the part online -

    Thermistor sensor (87161423020) Once home I connected the new sensor before removing the old one and the HW worked so I removed the old one fitted the new one and have hot water again and a happy household once more.

    I hope that the above helps someone else in the future.
    • Thanks Thanks x 1
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