WB 30CDi E9 error

[abanana]

Hi,

Boiler has just started tripping into E9 error state when the shower is being used. Happens after approx 10-15 mins of shower running. Pressing the reset button on the boiler gets it all working again, until the shower is used again.

Reading around here and other places on the Internet suggests that the plate heat exchanger may need changing. Anyone else able to offer any further insight?

Additional information: Boiler was serviced about a month ago. Pressure vessel was replaced at that time and some more inhibitor was put into the CH system.

Thanks!

 

[AGAS]

you need an engineer , overheating lock out

 

[abanana]

Thanks, I think. Yes, the engineer has already been out, talked to me about it, talked to WB tech support about it, concluded that it's likely to be the plate heat exchanger, but can't be certain as it *could* be other things. I was seeking input from other engineers that have experience with these boilers as to what they think it could be to try and make a more informed decision as to what to do as I'm trying to mitigate the cost risk of replacing things in the boiler purely for a fault-finding process (i.e. I'd like to try and have more information so that the first replacement item/work carried out fixes it, rather than the third or fourth attempt at a fix, which is what has happened with this boiler in the past).

Does anyone have any actual informed opinion as to what it most likely is based on their experience of these boilers?

Thanks.