I don't have a problem. Am just curious.
In my previous ex-LA house the central heating pipes were mainly visible along the skirting boards and were also routed upstairs under the floorboards. It was possible therefore to inspect the piping for leaks quite easily.
In my current house, built in 2004, all piping is hidden under the tiled floors. Only the little stubs that pop up through the floor tiling where the radiators connect are visible.
Question: When such piping is installed, is it pressure tested in some way? I could imagine discovering where a leak is with hidden piping could be a very costly business. One would have to lift some or all of the floor tiles for a start.
MM