When called to a fault on water boiler i isolated it and removed the front cover to find at the bottom of the boiler where the spout is for extracting hot water a single conductor (2.5mm2) wrapped around the 15 mm copper pipe the conductor worked from left to right then looping back on its self winding right to left. both ends of conductor went into small control unit.
anyone have any idea what this is for?


the type of boiler was the kind suspended above a sink for instant hot water(when they work)