Judging by the unpainted copper pipework above the pump, where the feed pipe and air separator are, I'd say this has already been replaced once before, due to problems.
Best to combine the feed and expansion pipe or seal up the CH system to unvented.
And get the filter moved if poss, onto the return to the boiler.
You could try draining the system and tap away at the pipes to see if this will encourage the f&e cistern to empty into the system and begin refilling. Or you can attach a hose to a drain point and try mains pressure to push the blockage back up into the f&e.
Best to combine the feed and expansion pipe or seal up the CH system to unvented.
And get the filter moved if poss, onto the return to the boiler.
You could try draining the system and tap away at the pipes to see if this will encourage the f&e cistern to empty into the system and begin refilling. Or you can attach a hose to a drain point and try mains pressure to push the blockage back up into the f&e.
