Ferroli Modena 80e hot water sticking on

[Kristoflampie]

Any of you guys come across this??
Turn hot tap on boiler fires and runs normally for hot water, turn tap off relay rattles like mad on new main PCB and keeps hot water light on , stops for a mo then relights kettling the boiler. Tried unhooking dhw flow switch, this doesnt cancel light , boiler just lights up again. Checked and changed both thermistors and checked wiring loom to board. Can only get it to switch back to heating or standby if tap is opened and shut a few times i.e settling the relay in the correct mode by chance. Checked for dribbling taps etc, no joy........ I am changing flow switch tomorrow, and bringing spare main pcb....... just in case original new one is faulty!
Your thoughts ??, anyone seen this fault??

 

[Kristoflampie]

Wee addition , Ferroli Technical guys had never heard of it and suggested the thermistors changed as we all know these are a weak point. Original fault was boiler occasionally switching itself on and unexplained lockouts........ another engineer changed the main board before I got there....... any thoughts??

 

[Kristoflampie]

just for infos sake........ flow switch / turbine was at fault.... sorted , for those who like answers

 

[Slugbabydotcom]

Just for reference if anyone else gets any probs with one of these

Been down near enough the same road today as it happens. except in my case the DHW and CH lights [3 & 4] were left flashing. A new 'MF03' PCB sorted it out.

The manual had an error in it as it said it was an 'MF02' PCB