Boiler overflow keeps leaking.

New house, still getting to grips with the heating system. I’ve got an unvented system, logic boiler downstairs, kingspan water cylinder upstairs.

Have got a heating engineer coming next week, but the system keeps losing pressure, we’re catching a lot of water from the boiler overflow pipe outside.

To keep the heating on we’re having to top up the system with water once or twice a day when it drops below 1bar (whilst the boiler is off). Is there any issues with doing this?