It has fired up the boiler and now my central heating seems to be working fine, just waiting for the hot water now, I'll keep you posted, thanks a million!!
hello Everyone, today I fitted a new Salamander shower pump, and as such I switched off the mains water tap, and also the outlet and inlets from the cylinder, and left the taps open so as to drain them.
I then finished and turned all of the valves back on.
Now the water is running fine...