Ideal Mini C24 Intermittent Lock Out

[ErinDIY]

So I have a Ideal Mini C24 Combi boiler, which when started from cold it seems to work with no problems, but once the boiler is warm, if the dhw or ch is requested it will ocaisionally lock out with the following error:

Faulty primary circuit
(no water or absence of flow)

Restarting the boiler or leaving it alone for 10+ minutes causes it to reset and the problem to go away temporarily but on average this lockout happens after about 2-5 minutes meaning very short showers.

Just before the lockout happens the the diverter will make a clicking sound and the diverter will move slightly but the pump will not start, the lockout happens about 10 seconds later since the flow switch is never triggered due to the pump not starting. Hitting the side of the boiler does seem to cause the pump to start mind. I have in an attempt to fix this issue, replaced the pump and done a chemical clean but the problem remains.

I am at a bit of a loss, the only things I can think of:

1) either the diverter is not fully activating with the pcb detecting its not fully activated and not starting the pump (but I don't think the actuator gives this type of feedback).
or
2)The relay that controls the power to the pump is playing up intermitently, but this does not explain why the problem only occurs when the boiler is hot, nore why hitting the side of the boiler just before the lockout causes the pump to start back up...

Any thoughts???

 

[ErinDIY]

Bit of an update, i pulled the cover off the pcb area to check for any cracks/burnouts. When the issue happens the relay that provides power to the pump doesnt switch, if i gentally tap the relay (with a insulated electric screw driver) the relay switches and the pump springs back to life. I've not taken the board out yet to check for dry joints, thats tomorow, but I think it may be easiest to simply order a replacement pcb and hope for the best.

 

[ErinDIY]

Swapped out the pcb, and all is working perfectly now!!! pcb was £30 from ebay... it took about 30 minutes to swap out, however do follow the manual and ensure any jumper settings match the original pcb... On a side note, I couldn't see any cracks/burnmarks or loose components on the pcb. I do believe it was simply a faulty relay.