any BS 5839 experts know whether CO alarms should be connected to the smoke/heat alarm system ? after completing an efixx CPD it seems they should not be , however multi alarms detectors exist with an optical and CO alarm in one unit and while that unit on the aico lights up to indicated CO or smoke/fire , how would the occupants know whether to ventilate ie for CO or to close doors for fire if they cant see that detector?