Yeah thanks, back to the 1st item i changed - good lesson learnt to check if the replacement part is the same as the one removed. Will pick up a new actuator tomorrow from the local gas merchant and try tomorrow night.
Yes AGAS going round in circles one could say, but at least I now now how...
Ahhaa, I looked at Fig 4 for the honeywell valves and agree with you logic on SPST so thought I had better double check the actuator fitted to the boiler and its different than the spare I acquired (which is Fig 3 and shows SPDT config), it is configured for SPST control (Pic below)
ok, Fig 3 is from the Honeywell manual for VC series valves and aligns with the wiring diagram shown on the actuator.
There is the chance the PCB I currently have fitted to the boiler and have measured the voltages off is a different PCB config than the one I have inspected !
I have ordered...
Which diagram do you think is wrong the relay ? I agree the actuator is 2 wire & common (3 wires) but I am sure having belled out the PCB the relay is the one I have inserted the diagram for above.
Thank you for the guidance.
A little more thinking / investigation as follows:
I suspected the Honeywell actuator 1st, so swopped out for a new (secondhand) one, same symptoms.
The diagram above is from the Honeywell spec.
I agree 240vac should be permanently on the NC terminal (Default...
Ok, double checked the DHW flow switch: open circuit - no water demand, close circuit - hot water demand.
So looks fine
I suspect the DHW Diverter valve relay on the PCB is stuck in the closed position, its probably the mechanical part on the PCB that gets worked the most (Hot water demand on...
Yeah could be, I need to have a deeper look as I disconnected the wiring harness to the switch and the fault didn't change but I will go back and look I was just google the circuit for the switch when you replied.
I have a fault on my boiler which is causing the Divert valve to continuously motor open/close with consequential impact on the CH and cycling hot/cold water when DHW demanded.
I have found 240v is permanently on the CLOSE terminal on the divert valve, when CH is demanded 240v is applied...