Thanks to everybody for their replies.
The boiler is now running again.
The fault appeared to be that that one of the leads into the actuator had fried it's insulation and the bare wire must have shorted out.
The lead has been repaired and the seal in the valve replaced. A new...
Thanks mr-crs.
Changed the actuator and that stopped the fuses blowing.
Fitted a new water pressure sensor and that cleared the fault on the panel.
System still not right though.
The DHW heats the water but I can feel the water temperature fluctuating at the tap. The heating fires...
Any ideas would be appreciated.
I have isolated the pump, fan and gas valve. Initially, the internal 2 amps fuses hold for about 10 minutes(boiler not running) and 'bar' warning light flashes but the pressure is fine. then blow. Replacement fuses blow immediately.
It appears as though some...