BES878 – heater not working after replacing bunch of parts

[Kah-Heng TAN]

I had a previous pump stuck-on problem where I replaced the main PCB to fix. It solved the pump problem but then the heater won’t heat up. (was fine with the previous faulty board)

I then replaced

– Triac board with a new one
– Printed heater assembly with a new one (SP0028450)

And still, the heater remains cold.

What else did I check?

1. Triac board – the triac seems to be ok. Multimeter check no shorts, diode test across the two outer legs read 60 (within spec?).
2. Continuity – red wire from leg of triac to the final point into the printed heater connection, white cable (from main PCB), brown cable. All OK
3. I even put back the previous bad main PCB. The pump issue returned but the heater remains cold.

I am absolutely at my wits end here. After replacing so many parts from the Ulka pump to the two solenoids, the water flow meter (all of which, up to that point in time, was to try to resolve the stuck-on pump), and now the PCB, the triac board and the printed heater assembly, I still don’t have a working machine. Everything seems to be operating fine, but just no hot water.

Not sure if this makes a difference: the new main PCB (SP0028451) and the new printed heater assembly (SP0028450) appear to be newer part models. The old PCB was pre-2020 – my BES878 was purchased in 2020.

Suggestions most welcome! Many thanks

[Author]

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