HI, I HAVE RECENTLY REPLACED A BATH AND SINK IN THE BATH ROOM, WHILST MAKING SOME OTHER CHANGES I ALSO DRILLED THROUGH A RADIATOR PIPE UNDER THE FLOORBOARDS, ALL HAS BEEN REPAIRED AND BLED THE RADIATORS BUT NOW, EVERYTIME WE USE THE HOT WATER TAP A LOUD HUMMING/VIBRATING SOUND IS HEARD FROM THE...