Greenstar 42 E9 then lockout

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I had a WB Greenstar 42CDi installed about 6 months ago, although being in the middle of refurbishing the entire house at the time I didn't really have any need to make use of DHW due to the lack of a bath or shower. Having now installed a bathroom suite, I'm making full use of hot water from the boiler for the first time. However, after running DHW for between 5-10 minutes and then adjusting the temperature down on the thermostatic shower (or indeed the bath mixer), the boiler will go into lockout displaying error E9.

As you'd expect, I've contacted the RGI who fitted it, and am waiting for him to get back to me. I have absolutely no intention of trying to cure this fault myself, not least because the boiler is still under guarantee, but I am curious as to where the fault could lie purely for my own interest.

Having run through the service guide it seems that the error is due to a high temperature limit. I have run through all the steps that can be completed without having to remove the cover, i.e. check CH circuit pressure between 1 and 2 bar, check pump not seized (can't be as CH works fine). I also can't see how either of the above should be relevant anyway, as I have been using CH for months and never had this fault, so it seems to be related to DHW only. The only thing I can see that might be causing the trip is high flue temperature.

I just wondered if there are any common problems on the WB greenstar range that could be the cause?

Thanks again!
 
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E9 is overheat.
More relevant info on the last few pages of your manual.
 
E9 is overheat.
More relevant info on the last few pages of your manual.

Thanks bengasman, but...

Having run through the service guide it seems that the error is due to a high temperature limit. I have run through all the steps that can be completed without having to remove the cover, i.e. check CH circuit pressure between 1 and 2 bar, check pump not seized (can't be as CH works fine). I also can't see how either of the above should be relevant anyway, as I have been using CH for months and never had this fault, so it seems to be related to DHW only. The only thing I can see that might be causing the trip is high flue temperature.

I appreciate that when you can't see the job, you can't be expected to diagnose the fault. However, I just thought that perhaps you gas engineers might be aware of some common faults on these units that can lead to E9.
 
I have installed every size of this series, and never had a problem with any of them.
Fully modulating, hence this should never happen.
My guess is either control issue, or not installed to spec.
 
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Me too,fitted a few of these 42 CDIs & the 37 CDIs in the past two years and a 550 CDI and have never had a single problem with any of them yet.

Only problem I've had with CDIs was a PCB on a 40 CDi conventional boiler going faulty two weeks out of warranty and WB replaced it FOC.
 
Thanks for that guys - will let you know the cause of the fault once I manage to get in touch with the engineer.
 
So, WB engineer came round, diagnosed as a blocked primary HX, replacement fitted. Still unsure as to the root cause of the problem though - he took a water sample from the system for analysis, but it certainly looked clean and the system was flushed when installed.
 

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