Established in the end its a sealed system by the top up/fill loop hose.
Filling a sealed C/heating system via top up loop [the only place I can find that would fill it, I hope]
It's the pain in the a**e back for the last time on this subject.
Coming to the end of how to do it so I can take notes for when the job is done and will impress my son - in -law as I won't tell him I'll let him think I know it all.
The loop is a flexi hose connection I assume used to top the system up when required. As this seems to be the only method of recharging the system I'll be doing it following replies. T
he tap on the hose is similar to the dishwasher/washing machine tap/s. Turning it on and I am assuming this will fill the system [in time].
However is there anything else I should do other than bleed the rads of air. I should say what I think is an air displacement valve in the airing cupboard on the central heationg pipe would just bleeding from that poiint be sufficient to expell all air out of the pipes and rads? or is there something elsel to be done? He said that when pressure gauge drops on the boiler he has to open this valve to bring up the pressure.