I've been asked to investigate pressure loss in a heating system. Pressure relief valve is ok. Expansion vessel is OK. Boiler heat exchanger is OK, plus it's a new boiler anyway. Cannot see leaks under the floors. But there is one screed floor with one radiator. The pipes are copper in a plastic sleeving. The start and end of the sleeving is visible, so would have thought water would have been seen coming from there if it were those pipes. It is a slow leak anyway, but can be seen on the gauge with the pressure loss. So, non invasive electronic leak detection type people time?