Removing cylinder and installing combi boiler. Pipe work query

[CLC plumbing]

I have a question regarding combi boiler installation. I’ve just completed an attic bathroom where the previous plumber had put in the first fix of qualpex down to the airing cupboard which is standard practice. I’ve come a later stage to finish the bathroom but I now find that in the airiing cupboard there’s no domestic hot water to make my connection . I have the cold,central heating but no hot for the facets. The cylinder has been taken out as a combi boiler was installed downstairs. The old expansion pipe seems to have a fill wave connected to 1/2” pipe. Would this be normal when installing a combi boiler? I would have expected it would be fed from the mains at the boiler..