Thanks for all your help chaps.
I did get to the bottom of it today and indeed it is a special 4044 namely the 4044F and as a couple of you stated it is a basic diverter with brown and blue going to the motor but has an added micro switch that connects the grey wire to the orange when the valve is fully across in the CH direction ie brown wire is live driving the motor. I managed to get a 4044F locally today and all is good.
I'm still slightly confused though and will do some more investigations. My confusion is if the orange only comes live when the valve is hard over in to the CH direction then the circulation pump will only run when feeding the CH. I thought it needed the pump to run when on HW as well to force the boiler output through the HW heat exchange.
I did get to the bottom of it today and indeed it is a special 4044 namely the 4044F and as a couple of you stated it is a basic diverter with brown and blue going to the motor but has an added micro switch that connects the grey wire to the orange when the valve is fully across in the CH direction ie brown wire is live driving the motor. I managed to get a 4044F locally today and all is good.
I'm still slightly confused though and will do some more investigations. My confusion is if the orange only comes live when the valve is hard over in to the CH direction then the circulation pump will only run when feeding the CH. I thought it needed the pump to run when on HW as well to force the boiler output through the HW heat exchange.