1. To start with - Are you able to test if the valve motor is getting power?
If so, then you will need to monitor if the voltage fluctuates the same as the motor, if the power is constant but the motor is not, then it is the motor
When I removed the motor and switched the boiler on the motor moved to the fully extended position. After I replaced the motor in the valve housing and switched on again I noticed the motor had moved to the lower position (CH only ?) and there it stays regardless of demand (CH/DHW)
Further to last reply, had a"lightbulb" moment, my water supply pressure is strong, so I turned it back to approx. 30% and tried the DHW
flow, it worked, and the central heating also, valve lever position is currently at the up position and CH and DHW seem to be OK for the moment. This leads me to think that its a pressure issue within the diverter valve itself. CH pressure is at 1.5 bar (about right I think) The ECO function is on, don't know if the diverter valve will move to the CH only function again or not it has't so far
Seems to be working OK for the moment, 3 bar you reckon, boiler label and instruction manual both say Max 10 bar, intend leave mains water tap at approx 30% turned on for the moment and see if that continues to work.1.3 Bar is the minumum and I think it's comfortably above that. Already have small inline valves on hot and cold tap supply both only half way on as water was bouncing off the sink and on to the floor! With all the rain we've had in the UK not surprised the water pressure is robust. Do you consider we've now reached a solution.
So you want me to crank up my mains water pressure to the max?
OK, will look into that, fairly straightforward to fit inline valve I think. Seems some sort of balance between CH pressure and mains pressure is required here. Perhaps I've arrived at the balance by accident.
OK, thanks for your help, signing off now.