Please HELP diagnose Suprima 50L problem

18 Nov 2007
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United Kingdom
Thanks to some great advice on this forum I have changed the following parts :

Suprima PCB (ebay job)
OH Stat
Motorised 3-port Valve

BUT.... I am still getting the 'lock-out' problem after the boiler has been in use for abour 30 mins or so. It is strange, it works perfectly when cold but it seems to lock-out once it has been running for about 30 mins. I have tried adjusting boiler temp control and thermostat but alas nothing. Does anyone have any ideas what is going on?

Forgot to add - Once the boiler is warm and it locks-out it wont reset and simply locks-out again immeditately unless I leave it for 10 mins or so......

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Your problem is in the second line of your post.... :LOL:
Ebay sell top notch stuff for boilers so it couldnt be the PCB, no way someone would sell a dodgy board on ebay?

So if its the PCB, why does it work perfectly for so long and then not? i.e why would usage and or heat affect a PCB? I find it hard to believe that I would be experiencing the same fault by swapping out the same board from a different supplier???
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The board could be from the same manufactured batch. Just a thort
id get sum1 out to look at it, but if i wa to guess either the pcb, pump, or the pump over-run not wired in

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