My father has had is boiler replaced and relocated.

There is now an old concrete flue which is in the chimny through to tge roof, where there is what looks like a vented aluminium cowl thing on top.

As the boiler has moves, he wants me to tidy up and decorate the area where the old boiler was.  I assume I need to leave the flue vented to avoid condensation?

He also says in heavy wind and rain he gets a wet worktop under the flue.  Is this likely to be driven rain entering the cowl on the roof, or possibly the mortar up there giving up?  I just want a rough idea of what to expect before climbing!